Abstract:
The present invention provides a method for removing nitrate from a solution comprising a salt component, wherein the method transplants sulfur bacteria to a sulfur-containing plant, and enables the sulfur-containing plant to which the sulfur bacteria is transplanted to contact a solution that comprises a salt component so as to remove nitrate from the solution comprising the salt component. The present invention also provides a solution comprising the salt component prepared by the method, and provides a salt comprising nitrate of 1.7 mg or lower per 100 g of salt.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a method of removing a nitrate from a solution containing a salt component, a solution containing a salt component in which the content of the nitrate has been minimized, and a salt in which the content of the nitrate has been minimized. 
       BACKGROUND ART 
       [0002]    Nitrate contained in salt is known as a risk factor of various diseases. That is, when nitrate is taken, the nitrate becomes nitrite by germs of the mouth, and the nitrite reacts with such materials as secondary amine and alchylamine contained in fishes, ports, grains, beer, etc. so as to generate N-nitroso compounds. Hence, when a lot of nitrate is taken, the nitrate can cause a cancer. Hence, it is necessary to take less nitrate, and thus is it needed to use salt which contains less nitrate. 
         [0003]    However, nitrate is inevitably generated in the process of preparing salt, and thus it is not easy to prepare salt with less nitrate. If seawater is evaporate to prepare salt, aerobic bacteria in the solution die or excrements decay, and in this process, ammonia is generated, the ammonia forms nitrite, and the nitrite becomes nitrate by microorganisms. Hence, even if the nitrate is completely removed in the state of solution in which salt has been melted, the salt, which is made therefrom, inevitably contains nitrate. The same is applied to other salts such as rock salt or salt in the desert. 
         [0004]    Hence, it may be better to use edible salt water in order to avoid nitrate because it is possible to completely remove nitrate in the salt water state. 
         [0005]    Further, even when raising marine fishes, nitrate give harmful effects on the survival of the marine fishes. Hence, the way to remove nitrate from the seawater is very important in the survival and growth of marine fishes. 
         [0006]    The currently known method of removing nitrate from salt water or seawater is to propagate sulfur bacteria by using mineral sulfur, and to decompose the nitrate into nitrogen or hydrogen sulfide (e.g.: Japanese Patent Publication No. 2002-273475) 
         [0007]    However, in this method, mineral sulfur may become a risk factor. That is, mineral sulfur is very harmful to human beings and other lives. Further, this method takes about 2 months in removing nitrate. Hence, using the conventional method in preparing edible salt water has a limit. 
       DISCLOSURE 
     Technical Problem 
       [0008]    An object of the present invention is to provide a method of rapidly removing nitrate from a solution containing a salt component by using a method which is not harmful to a human body. 
         [0009]    Furthermore, another object of the present invention is to provide a solution containing a salt component from which nitrate has been removed by the above method. 
         [0010]    Furthermore, another object of the present invention is to provide a salt in which the content of nitrate has been minimized (less than 1.7 mg/100 g). 
         [0011]    Furthermore, another object of the present invention is to provide a salt in which the content of sodium has been minimized. 
         [0012]    Furthermore, another object of the present invention is to provide a salt in which the salty state has been significantly reinforced by containing vegetable edible sulfur. 
         [0013]    Furthermore, another object of the present invention is to provide a solution containing a salt component containing the vegetable&#39;s unique flavor. 
       Technical Solution 
       [0014]    The present invention provides 
         [0015]    A method of removing nitrate from a solution containing a salt component in which the method transplants sulfur bacteria to a sulfur-containing plant, and enables the sulfur-containing plant to which the sulfur bacteria is transplanted to contact a solution that contains a salt component so as to remove nitrate from the solution containing the salt component. 
         [0016]    Further, the present invention provides 
         [0017]    A solution containing a salt component from which nitrate has been removed by the above method. 
         [0018]    Further, the present invention provides 
         [0019]    Salt in which the content of nitrate is less than 1.7 mg/100 g by evaporating water by heating the solution containing the salt component from which nitrate has been removed. 
         [0020]    Further, the present inventions provides 
         [0021]    Salt containing vegetable edible sulfur. 
       Advantageous Effects 
       [0022]    According to the method of removing nitrate of the present invention, plants containing edible sulfur, which is not harmful to the human body, is used as a source of nutrition of sulfur bacteria, and thus this is very safe and nitrate is very quickly removed from a solution containing a salt component (about 2 to 5 times faster than the existing products). 
         [0023]    Hence, the solution containing a salt component, which is prepared by the method of removing nitrate of the present invention, may be very useful in growth of edible lives or lives in the sea. 
         [0024]    Furthermore, in the salt of the present invention, the content of nitrate is minimized, and thus the salt may be very useful in growth of edible lives or lives in the sea. 
         [0025]    Furthermore, according to the present invention, sodium is consumed by sulfur bacteria in the preparation process, and thus it is possible to provide salt in which the content of sodium has been minimized. 
         [0026]    Furthermore, according to the present invention, salt, in which the salty taste has been significantly reinforced by containing edible sulfur, is provided, thereby significantly reducing the consumption of sodium. 
         [0027]    Furthermore, according to the present invention, a solution and salt containing a salt component containing the plant&#39;s unique flavor may be provided. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0028]      FIG. 1  shows a result of identifying bacteria containing in a salt water of 3-9% salinity from a salt farm in Sinan area (west sea of Korea) by using a temperature gradient gel electrophoresis (TGGE) method. 
       
    
    
     BEST MODE 
       [0029]    The present invention relates to 
         [0030]    a method for removing nitrate from a solution comprising a salt component, wherein the method transplants sulfur bacteria to a sulfur-containing plant, and enables the sulfur-containing plant to which the sulfur bacteria is transplanted to contact a solution that comprises a salt component so as to remove nitrate from the solution comprising the salt component. 
         [0031]    In the present invention, plantation of sulfur bacteria is used as a concept including the proliferated state after transplantation of sulfur bacteria. 
         [0032]    Sulfur (element symbol S, atomic number 16, atomic weight 32.066, and an element which belongs to 16(6B) group of the periodic table) is an essential nutrient element of all plants. Sulfur is taken by plants or microorganisms in the form of a sulfate, and the sulfate is reduced to hydrogen sulfide and the hydrogen sulfide may be used in synthesizing amino acids containing sulfur. Further, sulfur is an important element of biological antioxidants like glutathione and various enzymes. Hence, sulfur exists in plants in various forms of enzymes. 
         [0033]    Edible sulfur in plants is used, and thus the effects of removing nitrate vary depending on the amount of sulfur contained in the plants used. Plants absorb mineral sulfur in the soil after converting the sulfur into edible sulfur, and thus the absorbed edible sulfur is not harmful to the human body. Hence, edible sulfur is being sold in the market as health supplements (e.g., currently, MSM, which is edible sulfur from pine trees, is sold as nutrients for arthritis. 
         [0034]    The content of edible sulfur varies depending on the species of plants, and the content of edible sulfur increases in the order of grasses, legumes, and flowers having 4 petals (grasses&lt;legumes&lt;flowers having 4 petals). Much sulfur is contained in cysteine and methionine, and sulfur is also an element of ferredoxin, biotin, glutathione, and coenzyme A. 
         [0035]    Some examples of plants, which contain the sulfur and may be effectively used in removing nitrate, are a Bambusoideae plant, a potato, a garlic, the stalk of a garlic, a ginger, a  ginkgo  nut, foxtail millet, Chinese millet, a black bean, a white bean, a red bean, a pea, a kidney bean, a mung bean, a African millet, grapefruit skin, lemon skin, mandarin orange skin, Hanrabong skin, lime skin, orange skin, kumquat skin, a ginseng, a carrot, a radish, a radish sprout, a broad bellflower, a green bean sprout, a bean sprout, a peanut, a mugwort, a pumpkin, rosemary, a rose, a branch of a pine, a pine needle, Acanthopanax, chard, a spring onion, a wild rocambole, a broccoli, a candle plant, a pineapple sage, a lemon balm, a spearmint, an apple mint, a pineapple mint, a green tea leaf, a cabbage, and a red cabbage. The above plants may be used solely or as a combination of two or more kinds. 
         [0036]    The roots, stalks, and leaves of the plants also show the same effects. 
         [0037]    The effects of the plants have been confirmed by experiments, but other plants containing various kinds of sulfurs may be used in the present invention. In particular, even when there is no or insufficient effects of removing nitrate, if there is the plant&#39;s unique flavor, it is possible for the plant to be combined with other plants having the effects of removing nitrate. 
         [0038]    That is, the function for removing nitrate may be set to be performed by plants containing sulfur having the effects of removing nitrate, and adding the flavor to the salt water or salt may be set to be performed by plants with no or insufficient effects of removing nitrate. Hence, it is possible to use plants without containing sulfur in the present invention in order to provide the plant&#39;s unique flavor. 
         [0039]    When salt water or salt, from which nitrate has been removed, is prepared, the plant&#39;s unique flavor is added to the salt water or salt, and thus it is possible to prepare salt water or salt having the plant&#39;s unique flavor (taste and smell). 
         [0040]    For example, bamboo shoots having strong effects of removing nitrate and pine needles having insignificant effects of removing nitrate are put together in a solution containing a salt element and the nitrate is removed, then salt water and salt with the fragrance of pine needles may be prepared. 
         [0041]    Further, salt water and salt with the fragrance of lemons or oranges, from which nitrate has been almost removed, may be prepared by using bamboo shoots and orange skin or lemon skin. This is different from salt having the fragrance of lemons and containing nitrate which is simply prepared by melting lemons. 
         [0042]    Further, by mixing beans (soybeans) with bamboo shoots, potassium is reinforced, and thus potassium-reinforced salt without nitrate for discharging sodium may be prepared. 
         [0043]    One of plants for effectively removing nitrate from among plants containing sulfur is bamboo shoots. Here, the bamboo is a general term of perennial plants which belong to Bambusoideae. In particular,  Sasa borealis  may be favorably used among the bamboos. 
         [0044]    The bamboo contains edible sulfur, and thus all of leaves, stems, shoots, and roots may be used. In particular, the roots of the bamboos contain a lot of stomata contain a lot of sulfur, and thus the roots may be favorably used in transplantation and propagation of sulfur bacteria. 
         [0045]    The amounts of sulfur elements of  Sasa borealis  are different depending on the produced area, the cultivated and harvested season, and the dried level. That is, the Nonsan area  Sasa borealis,  which is produced in summer, contains less sulfur, and Jeju area  Sasa borealis,  which is produced in the volcanic region, contains relatively a large amount of sulfur. Hence, it is preferable to select and use bamboos containing a lot of sulfur. 
         [0046]    The capabilities of removing nitrate of plants containing sulfur are as follows. 
         [0047]    Bamboo shoots&gt;legumes&gt;Chinese millets, foxtail millets&gt;garlics, garlic flower stalks&gt;potatoes, gingers&gt;skins of mandarin oranges, etc.&gt; ginkgo  nuts,  ginkgo  nut leaves 
         [0048]    However, such a result may be different depending on various conditions such as salinity, cultivating environment, cultivating time, and experiment temperature. For example, in the case of plants which use a lot of nitrogenous fertilizers, the plants themselves may contain a lot of nitrate, and thus it may be difficult to exhibit desirable effects in the use of removing nitrate. Hence, the plants, which do not use the nitrogenous fertilizers, may be appropriately used in the present invention. 
         [0049]    In the present invention, sulfur bacteria are classified as sulfur reduction bacteria and sulfur oxidation bacteria. 
         [0050]    The sulfur bacteria are germs which obtain energy needed in the growth by oxidizing sulfur or inorganic compounds, and grow in salt water of a salt farm, soil, etc. The sulfur bacteria may include Leucothiobacteria and chromothiobacteria. 
         [0051]    Sulfur bacteria oxidize hydrogen sulfide, other sulfides, etc. for proliferation, and do not need organic carbon compounds in the nutrition. 
         [0052]    Leucothiobacteria include  Beggiatoa  and  Thiothrix,  and some like alkalinity and some others like acidity. 
         [0053]    Chromothiobacteria include  Thiobacillus  and perform photosynthesis with red or green pigments and by using sunbeam. 
         [0054]    Sulfate reducing bacteria and sulfur reducing bacteria may be used as the sulfur reducing germs. 
         [0055]    Some examples of the sulfate reducing bacteria are  Desulfovibrio  and  Desulfotomaculum,  and an example of sulfur reducing bacteria is  Desulfuromonas.    
         [0056]    Further, sulfur oxidation bacteria may be used in the present invention. 
         [0057]    (1)  Marinobacter  sp. GenBank accession number JQ618280 
         [0058]      Marinobacter  sp. germs exhibit the highest denitrification effects in the salt concentration of 3 to 6%. The concentration of salt, which shows the optimal denitrification, is 3%. Neutral pH is most appropriate.  Marinobacter  sp. germs have the function of reducing nitrate into molecular nitrogen (N2) by using succinate as the energy source. The denitrification effects are shown in anaerobic conditions without oxygen, and thus it is possible to live in deposits on the floor of the ocean (related theses: Miyo Nakano, Tadashi Inagaki, SuguruOkunishi, Reiji Tanaka and Hiroto Maeda, “Effect of salinity on denitrification under limited single carbon source by  Marinobacter  sp. isolated from marine sediment”. Journal of Basic Microbiology, 2010, 50, pages 285-289; 
         [0059]    Bo-Ram Choi, VinhHoa Pham, Soo-Je Park, So-Jeong Kim, Dong-Hyun Roh, Sung-Keun Rhee, “Chracterization of facultative sulfur-oxidizing  Marinobacter  sp. BR13 isolated from marine sediment of yellow sea, Korea”, Journal of Korean Society for Applied Biological Chemistry, 2009, 52, pages 309-314). 
         [0060]    In the above second thesis, germs, which are separated from deposits of the Yellow Sea in Korea, may grow in the range of 0.5 to 9% salt concentration and 7 to 37° C. and use sugar and organic acids, etc. as the carbon source. In the concentrating culturing process, the germs grow by using thiosulphate as the energy source, and thus they are referred to as selective sulfation bacteria 
         [0061]    (2)  Marispirillum indicum,  GenBank accession number NR044545 
         [0062]      Marispirillum indicum  grows in the ragne of 0.5 to 12% salt concentration and 10 to 41° C. And has denitrification effects (related thesis: Lai Q, Yuan J, Gu L and Shao Z., “ Marispirillumindicumgen. nov.,  sp.  nov.,  isolated from a deep-sea environment”, International Journal of Systematic and Evolutionary Microbiology, 2009, 59, pages 1278-1281). 
         [0063]    (3)  Thalassospira  sp. GenBank accession number AB373113 
         [0064]    Germs, which use aromatic hydrocarbon compounds and belong to  Thalassospira  sp., grow in the 2 to 14% salt concentration, but the optimal salt concentration for growth is 3% as in the seawater. The germs grow in the range of 8 to 45° C., but the optimal temperature for growth is 43° C. The germs may use glucose as the substrate and have the function of reducing nitrate (related thesis: Yumiko Kodama, Lies Indah Stiknowati, Atsuko Ueki, Katsuji Ueki and Kazuya Watanabe,  Thalassospira tepidiphila  sp.  nov.,  a polycyclicaromatic hydrocarbon-degrading bacteriumisolated from seawater”, International Journal of Systematic and Evolutionary Microbiology, 2008, 58, pages 711-715). 
         [0065]    (4)  Caminibacillus  sp. GenBank accession number AB752312 
         [0066]    They grow in the range of 45 to 65° C., and the optimal temperature is 55 to 60° C. They grow around the hot water gushing part of the deep sea. In the hot water gushing part, sulfur is gushed, and thus the sulfur may be oxidized and used as the energy source. The growth is possible in the salt concentration of 2 to 6%. They have the function of reducing the nitrate in the anaerobic condition (related thesis: Alain K, Pignet P, Zbinden M, Quillevere M, Duchiron F, Donval J P, Lesongeur F, Raguenes G, Crassous P, Querellou J, and Cambon-Bonavita M A. “ Caminicella ( Caminibacillus )  sporogenes  gen.  nov.,  sp.  nov.,  a novel thermophilic spore-forming bacterium isolated from an East-Pacific Rise hydrothermal vent”, International Journal of Systematic and Evolutionary Microbiology, 2002, 52, pages 1621-1628). 
         [0067]      Tepidibacter formici  genes, GenBank accession number JQ670743 
         [0068]    They are sporforming Chemoheterotrophic germs. They may grow in the range of 2 to 6% salt concentration, but the optimal concentration is 3%. The pH range for growth is 5 to 8, and the organic matters (sugar, organic acids) are used as nutrition for growth (related thesis: Urios L, Cueff V, Pignet P, and Barbier G. “ Tepidibacter formici  genes sp.  nov.,  a novel spore-forming bacterium isolated from a Mid-Atlantic Ridge hydrothermal vent”, International Journal of Systematic and Evolutionary Microbiology, 2004, 54, pages 439-443). 
         [0069]    Further, in the present invention, the following denitrification bacteria may be used along with sulfur bacteria. 
         [0070]    (6)  Geosporobacter subterraneus,  GenBank accession number DQ643978 
         [0071]    They grow in the deep sea, and thus they use organic materials as the substrate. They may grow in the range of 30 to 55° C., but the optimal temperature is 42° C. The optimal salt concentration for growth is 4%. They may grow in the range of pH 5.6 to 8.4, but the optimal pH is 7.3 (related thesis: Klouche N, Fardeau M L, Lascourreges J F, Cayol J L, Hacene H, Thomas P, and Magot M., “ Geosporobacter subterraneus  gen.  nov.,  sp.  nov.,  a spore-forming bacterium isolated from a deep subsurface aquifer”, International Journal of Systematic and Evolutionary Microbiology, 2007, 57, pages 1757-1761). 
         [0072]    (7)  Firmicutes bacterium,  GenBank accession number JX240960 
         [0073]    Firmcutes are not halophilic, but may be in charge of denitrification in the low salt concentration less than 3% (related thesis: Young-Woon Lim, Soon-Ae Lee, Seung Bum Kim3, Hae-Young Yong2, Seon-HeeYeon, Yong-Keun Park, Dong-Woo Jeong, and Jin-Sook Park, “Diversity of Denitrifying bacteria isolated from Daejeon sewage treatment plant”, The Journal of Microbiology, 2005, 43, pages 383-390). 
         [0074]    Among the germs, the germs, which belong to  Marinobacter, Marispirillum, Thalassospira,  and  Caminobacillus,  are in charge of denitrification in the environment with a high salinity. Among the germs, Nos. 1, 2, 3, 4, and 5, which are sulfation bacteria, are mainly oxidized to generate biochemical energy and denitrification germs (Nos. 5, 6, and 7) reduce nitrate by using the energy source produced by other germs, and thus when the sulfation bacteria and denitrification germs are used together, sulfation and the reduction of nitrate may be performed. 
         [0075]    Among the germs, no. 5 is bacteria which inhabit in places without a lot of sulfur, and at the same time, organic matters are also used as nutrients. 
         [0076]    The germs do not reduce the nitrate with the energy source which is generated by only the biochemical oxidation process of sulfur in the condition that the organic matters are completely excluded, but use various organic matters and sulfur as the energy source which exist in the water, and remove nitrate by the denitrification reaction by producing biochemical energy by using nitrate as the electron accepter instead of oxygen in the anaerobic condition. 
         [0077]    Oxidation bacteria of nos. 1, 2, 3, 4, and 5 and denitrification bacteria of nos. 6 and 7 appropriately remove nitrate by using edible sulfur and organic matters as the energy source even in a high salinity (3% or more). 
         [0078]    Bacteria of nos. 1 to 7 may be extracted from salt water of a salt farm of the salinity of 3 to 27% (w/v). For example, the extraction may be performed by transplanting bacteria after putting a plant containing sulfur in the salt water of a salt form or seawater in the deep sea of the salinity of 3 to 27% (w/v). 
         [0079]    Hence, when bacteria, which is extracted from the salt water of a salt farm of the salinity of 3 to 27%, are used, all nutrients, which are needed in the growth of germs such as sulfur and organic matters from plants containing sulfur, are supplied, and thus nitrate may be efficiently removed. 
         [0080]    The bacteria are well proliferated even in temperatures of 5 to 70° C. and absorb nitrate well. 
         [0081]    In the present invention, a solution containing a salt element refers to a solution in which a salt element, i.e., NaCl is melted, and more specifically, refers to salt water or seawater. 
         [0082]    This method may be performed in a manner that additionally dips a plant containing sulfur which is not bacteria-transplanted in the step of making the plant containing the bacteria-transplanted sulfur contact the solution containing the salt element for removing nitrate. 
         [0083]    Further, the method may be performed in a manner that makes the plants without bacteria-transplanted sulfur as well as plants with sulfur contact the solution containing the salt element in the step of making the plant containing the bacteria-transplanted sulfur contact the solution containing the salt element for removing nitrate. In this case, the added plant does not contain sulfur and thus does not remove nitrate, but may provide the plant&#39;s unique flavor to the salt water. 
         [0084]    Further, the method may also be performed in a manner that further dips the plant without sulfur as well as the plant with sulfur, to which bacteria has not been transplanted, in the step of making the plant containing the bacteria-transplanted sulfur contact the solution containing the salt element for removing nitrate. 
         [0085]    Further, the method may be performed in a manner that adds edible sulfur extracts extracted from plants containing sulfur in the step of making the plant containing bacteria-transplanted sulfur contact the solution containing the salt element for removing nitrate. 
         [0086]    Further, all these processes may also be performed by extracting edible sulfur from a plant containing sulfur. In this case, edible sulfur may be extracted by a method which is commonly used in this field. For example, a plant containing sulfur may be boiled in the water of 50 to 120° C. so as to extract edible sulfur. 
         [0087]    However, some bacteria remove nitrate by decomposing organic matters, and thus it is more desirable to directly use a plant containing sulfur so that unique organic matters contained in fibroid materials may be used together. 
         [0088]    In the method of the present invention, only a small amount of plants from among the overall plants containing sulfur may be used in the operation of transplanting bacteria, and the other plants contacting sulfur may be preferably dipped in the solution containing the salt element for removing nitrate. It is because there are plants which are easy to transplant sulfur bacteria and plants which are difficult to directly transplant sulfur bacteria, from among plants containing sulfur. Hence, plants having a hard structure like bamboos and  Sasa borealis  have a favorable condition for transplanting sulfur bacteria, and thus nitrate can be more effectively removed if the sulfur bacteria are transplanted in  Sasa borealis,  then the pieces of the  Sasa borealis  are put in a plant having a lot of edible sulfur. 
         [0089]    A plant having bacteria-transplanted sulfur and a plant having sulfur to which bacteria have not been transplanted may be the same plant or different plants. 
         [0090]    The method of removing nitrate of the present invention is preferably performed in anaerobic conditions. It is because sulfur bacteria remove nitrate by denitrification reaction by producing biochemical energy by using nitrate as the electron acceptor instead of oxygen in anaerobic conditions. That is, in aerobic conditions, sulfur bacteria use oxygen as the electron acceptor, and thus it is difficult to expect the effects of removing nitrate. 
         [0091]    Further, the present invention relates to 
         [0092]    a solution containing a salt element from which nitrate has been removed. 
         [0093]    Some examples of such a solution containing the salt element are edible salt water and seawater. 
         [0094]    The edible salt water includes salt water which is used in the process of preparing foods. The salt water may be very usefully used as a substitute of salt. For example, the salt water may be used to season a food with salt, may be used as a coagulant at the time of preparing bean curd, and may be used to salt kimchi. 
         [0095]    The present invention relates to 
         [0096]    A salt having less than 1.7 mg nitrate per 100 g salt, which is prepared by evaporating water from a solution containing a salt element. 
         [0097]    Here, it is even better to set the level of nitrate to be less than 1 mg per 100 g salt. 
         [0098]    The salt water of a high salinity (greater than 25%), from which nitrate has been completely removed, has sulfur bacteria therein. However, such activities become dull in the high salinity state, and the bacteria die in the process when salt is made by water evaporation so as to generate nitrate. Hence, it is impossible to prepare salt from which nitrate has been almost completely removed. 
         [0099]    However, the salt water, which is prepared by removing nitrate by the method of the present invention, is rapidly heated in the range of 90 to 120° C., is rapidly heated by a microwave oven, is rapidly evaporated by strong light, or is lyophilized, it is possible to obtain salt with less than 1.7 mg nitrate/100 g salt. In particular, in the case of lyophilization, bacteria in the lyophilized salt is not rotten, but is dried, and thus the content of nitrate rarely increases. 
         [0100]    Here, the rapid heating means 1 to 30 minutes, but preferably completing drying for 1 to 10 minutes. 
         [0101]    The content of nitrate of bay salt sold in the market is about 4.3 to 6.7 mg/100 g, and the content of nitrate of chemical salt is about 3.7 mg/100 g. Salt with less nitrate is not known. Further, it is recognized that to prepare such salt is very difficult. 
         [0102]    Hence, when considering this situation, salt with less than 5 mg nitrate of the present invention is very significant. 
         [0103]    According to the present invention, salt with minimum nitrate is prepared by allowing bacteria to remain in a form like nucleic acid within salt by rapidly evaporating water from salt water of very high salinity. 
         [0104]    Further, the present invention provides salt in which the content of sodium is minimized. 
         [0105]    A very small amount of sodium is required in metabolism of some bacteria. Sodium plays an important role in movement of materials with electric charge in eukaryotic cells. Halophilic bacteria need sodium (Na+) for movement of materials (BIOPROCESS ENGINEERING BASIC CONCEPTS, second edition, MICHAEL L. SHULER, page 59). In the present invention, halophilic sulfur bacteria are used, and such halophilic bacteria use a very little amount of sodium. Hence, it is possible to provide salt in which the content of sodium has been minimized. 
         [0106]    The present invention also provides salt which contains vegetable edible sulfur. The vegetable edible sulfur performs a function of reinforcing the salty taste of salt. 
         [0107]    The salt, from which nitrate has been removed by sulfur bacteria, is salty twice than the existing refined salt. It is because edible sulfur and potassium contained in bamboo shoots or legumes taste bitter. Potassium and edible sulfur contained in plants usually taste bitter and provide effects of making those who taste the salt feel more salty. That is, salt, which is prepared by the present invention by using edible sulfur and sulfur bacteria, still contains edible sulfur, and thus the salty taste is significantly reinforced. Currently, salt, in which the salty taste has been reinforced by using the bitter taste of potassium, is sold to reduce the intake of sodium, but according to the present invention, the salty taste is reinforced more safely by using edible sulfur. 
         [0108]    When more than 500 mg edible sulfur is contained in 50 g salt, a person can feel reinforced salty taste, and when about 1500 mg edible sulfur is contained in 50 g salt, the salty taste is doubled. The content of edible sulfur contained in the salt may vary according to the kind of plants or the number of sulfur bacteria used. 
         [0109]    Salt water and salt of high salinity, which are obtained by sulfur bacteria in the present invention, also have effects in reducing the speed of natural nitrate increase in vegetables and foods. 
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0110]    Hereinafter, the present invention will be described with reference to the embodiments. However, the present invention is not limited to the embodiments described below and it is obvious that the embodiments can be changed to other embodiments within the scope of the present invention. 
       COMPARATIVE EXAMPLE 1 
     Preparation of Salt Water without Nitrate 
       [0111]    Nitrate remover sold in the market (mineral sulfur is used) (product name: LSM, manufacturing company: Sarib-sea) was purchased so as to remove nitrate contained in salt water. First, salt water 1 L of 9% salinity is poured in a cylinder-shaped container, and the nitrate remover is added according to the amount of use displayed in the products. The concentration of nitrate is checked with the nitrate measuring kit after waiting for some time until the nitrate is removed enough. As a result, it was found that the concentration of nitrate became 0 mg/L after 60 days. 
       First Embodiment: Preparation of Salt Without Nitrate (Sulfur Reducing Bacteria is Used) 
       [0112]    10 L salt water of 9% salinity containing nitrate is poured in a cylinder-shaped container. Roots of  Sasa borealis  are but into pieces of 1 cm to 2 cm, and sulfur reducing bacteria (LSM of Carbi Sea company is purchased and extracted; the bacteria name is sulfur reducing bacteria, “Desulfuromonas”) is transplanted. And the bacteria-transplanted roots of  Sasa borealis  are filled from the bottom of the cylinder-shaped container to the surface of the water. Temperature is maintained at normal temperatures, and the container is covered with a lid to block the external air. The concentration of the nitrate was measured after 6 days from the starting date, and it was confirmed that the concentration of nitrate was 0 mg/L and the  Sasa borealis  pieces were taken out from the cylinder-shaped container. The remaining salt water was filtered and was then poured in a separate container to prepare salt water without nitrate. 
         [0113]    As checked in the above experiment, the method of removing nitrate of the present invention is much faster (about 2 to 3 times) than that of the products which are now sold in the market. 
       Second Embodiment: Preparation of Salt Water without Nitrate 
       [0114]    (1) Extracting Bacteria from Salt Water in a Salt Farm 
         [0115]    1) Method of Directly Transplanting Bacteria in a Plant to be Used 
         [0116]    A plant (root pieces of  Sasa borealis ) containing sulfur which has been cut into pieces of 1 to 2 cm is put in the salt water of 9% salinity from a salt farm of Sinan area of West Sea of Korea, and it is then matured in the range of 20 to 35° C. for three days so as to transplant bacteria in  Sasa borealis.    
         [0117]    2) Method of Preparing Bacteria Transplanted Pieces by Using a Separate Plant 
         [0118]    Transplanted pieces (root pieces of  Sasa borealis ) which have been cut into pieces of 1 to 2 cm are put in the salt water of 9% salinity from a salt farm of Sinan area of West Sea of Korea, and they are then matured in the range of 20 to 35° C. for 15 days so as to transplant and proliferate sulfation bacteria in  Sasa borealis.    
         [0119]    (2) Removing Nitrate from Salt Water (Sulfation Bacteria, etc. are Used) 
         [0120]    A glass container of 180 ml to be used in an experiment and salt water of 9% (3 to 28% are possible) salinity of bay salt are disinfected in 90° F. in order to prevent entrance of other bacteria, and plants to be used are also sterilized by dipping them in boiled water for 5 seconds to prevent entrance of other bacteria. 
         [0121]    Salt water is poured in the glass container, and the concentration of nitrate is measured with absorption scheme of the spectrophotometer and the No 3 profi test kit color measurement scheme of Tetra and Salifert. Then each 30 g plant of Table 1 is put in the glass container so that salt water is not overflown, and one of root pieces (1 to 2 cm) of  Sasa borealis  which is obtained by proliferating sulfation bacteria is put in plants and then the container is shaken slightly not to have a bubble. 
         [0122]    The experimental container is matured in the temperature range of 20 to 35° C., and the removed amount of nitrate is measured with the absorption scheme of the spectrophotometer and the No 3 profi test kit color measurement scheme of Tetra and Salifert. 
         [0123]    Here, the plants are washed and are cut into pieces of 1 to 2 cm so as to be used. Fruits such as beans, mung beans, foxtail millet, and  gingko  nuts are used as themselves just after peeling off the skin. Other branches and some things with a large volume have been cut into pieces of 1 to 2 cm so as to be used. Plants are cut into pieces for easy contact between edible sulfur and sulfur bacteria and growth. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                 Measuring days 
                   
               
               
                   
                   
                   
                 (Maturing period) 
                   
               
               
                   
                   
                   
                 (Period when 
                   
               
               
                   
                   
                 Content of nitrate 
                 nitrate is 
                   
               
               
                   
                 Plant 
                 (mg/l) 
                 removed much) 
                 Remarks 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 Bamboo shoot 
                 1  
                 mg/l or less 
                 4-6  
                 days 
                 Possible to remove nitrate up to 0 mg/l 
               
               
                 2 
                 Root of Sasa 
                 2 
                 mg/l or less 
                 5-9  
                 days 
                 Nitrate concentration increases during the first 
               
               
                   
                 borealis 
                   
                   
                   
                   
                 1 to 3 days, and from the fourth day, the nitrate 
               
               
                   
                   
                   
                   
                   
                   
                 removed. 
               
               
                 3 
                 Potato 
                 2  
                 mg/l or less 
                 3-6  
                 days 
                 Possible to remove nitrate up to 0 mg/l, but when  
               
               
                   
                   
                   
                   
                   
                   
                 matured for a long time, nitrate concentration 
               
               
                   
                   
                   
                   
                   
                   
                 increases 
               
               
                 4 
                 Garlic 
                 2  
                 mg/l or less 
                 3-4  
                 days 
                 When matured for more than 12 days, nitrate 
               
               
                   
                   
                   
                   
                   
                   
                 concentration increases again/bubbles are  
               
               
                   
                   
                   
                   
                   
                   
                 generated/when preparing salt,  
               
               
                   
                   
                   
                   
                   
                   
                 garlic smell is strong 
               
               
                 5 
                 Stalk of garlic 
                 2  
                 mg/l or less 
                 4-12  
                 days 
                 Nitrate is removed as matured longer than garlic 
               
               
                 6 
                 Ginger 
                 2  
                 mg/l or less 
                 7-14  
                 days 
                 Nitrate concentration slightly increases at first 
               
               
                   
                   
                   
                   
                   
                   
                 1 to 6 days, and then nitrate is removed. 
               
               
                 7 
                 Ginkgo nut 
                 2 
                 mg/l or less 
                 4-5  
                 days 
                 Possible to remove nitrate up to 0 mg/l 
               
               
                 8 
                 Ginkgo leaf 
                 2  
                 mg/l or less 
                 10-15 
                   
                 Have effects, but after 15 days, decayed smell may be 
               
               
                   
                   
                   
                   
                   
                   
                 generated 
               
               
                 9 
                 Foxtail millet 
                 2 
                 mg/l or less 
                 3-20  
                 days 
                 When matured even for a month, nitrate concentration does 
               
               
                   
                   
                   
                   
                   
                   
                 not increase again. Possible to remove nitrate up 
               
               
                   
                   
                   
                   
                   
                   
                 to 0 mg/l 
               
               
                 10 
                 Chinese millet 
                 2  
                 mg/l or less 
                 3-20  
                 days 
                 When matured even for a month, nitrate concentration does 
               
               
                   
                   
                   
                   
                   
                   
                 not increase again. Possible to remove nitrate up 
               
               
                   
                   
                   
                   
                   
                   
                 to 0 mg/l 
               
               
                 11 
                 Black bean 
                 2  
                 mg/l or less 
                 4-20  
                 days 
                 When matured even for a month, nitrate concentration does 
               
               
                   
                   
                   
                   
                   
                   
                 not increase again. 
               
               
                 12 
                 White bean 
                 2  
                 mg/l or less 
                 4-20  
                 days 
                 When matured even for a month, nitrate concentration does 
               
               
                   
                   
                   
                   
                   
                   
                 not increase again. 
               
               
                 13 
                 Red bean 
                 3  
                 mg/l or less 
                 4-15  
                 days 
                 When matured even for a month, nitrate concentration does 
               
               
                   
                   
                   
                   
                   
                   
                 not increase again. 
               
               
                 14 
                 Pea 
                 3  
                 mg/l or less 
                 4-20  
                 days 
                 When matured even for a month, nitrate concentration does 
               
               
                   
                   
                   
                   
                   
                   
                 not increase again. 
               
               
                 15 
                 Kidney bean 
                 3  
                 mg/l or less 
                 4-20  
                 days 
                 When matured even for a month, nitrate concentration does 
               
               
                   
                   
                   
                   
                   
                   
                 not increase again. 
               
               
                 16 
                 Mung bean 
                 2  
                 mg/l or less 
                 4-25  
                 days 
                 When matured even for a month, nitrate concentration does 
               
               
                   
                   
                   
                   
                   
                   
                 not increase again. Possible to remove nitrate up  
               
               
                   
                   
                   
                   
                   
                   
                 to 0 mg/l 
               
               
                 17 
                 African millet 
                 4  
                 mg/l or less 
                 4-15  
                 days 
                   
               
               
                 18 
                 Grapefruit skin 
                 3  
                 mg/l or less 
                 4-8  
                 days 
                 When matured for more than 20 days, nitrate  
               
               
                   
                   
                   
                   
                   
                   
                 concentration increases slightly 
               
               
                 19 
                 Lemon skin 
                 3  
                 mg/l or less 
                 4-15  
                 days 
                 Up to 25 days, nitrate concentration does not increase 
               
               
                   
                   
                   
                   
                   
                   
                 again. 
               
               
                 20 
                 Mandarin orange 
                 3  
                 mg/l or less 
                 4-15  
                 days 
                 Up to 25 days, nitrate concentration does not increase 
               
               
                   
                 skin 
                   
                   
                   
                   
                 again. 
               
               
                 21 
                 Hanrabong skin 
                 3  
                 mg/l or less 
                 4-10  
                 days 
                 Up to 25 days, nitrate concentration does not increase 
               
               
                   
                   
                   
                   
                   
                   
                 again. 
               
               
                 22 
                 Lime skin 
                 3  
                 mg/l or less 
                 4-12  
                 days 
                 Up to one month, nitrate concentration does not 
               
               
                   
                   
                   
                   
                   
                   
                 increase again. 
               
               
                 23 
                 Orange skin 
                 3  
                 mg/l or less 
                 4-15  
                 days 
                 Up to one month, nitrate concentration does not 
               
               
                   
                   
                   
                   
                   
                   
                 increase again. 
               
               
                 24 
                 Kumquat skin 
                 3  
                 mg/l or less 
                 4-12  
                 days 
                 Up to one month, nitrate concentration does not 
               
               
                   
                   
                   
                   
                   
                   
                 increase again. 
               
               
                 25 
                 Pomegranate skin 
                 3 
                 mg/l or less 
                 4-12  
                 days 
                 Up to one month, nitrate concentration does not 
               
               
                   
                   
                   
                   
                   
                   
                 increase again. 
               
               
                 26 
                 Ginseng 
                 4  
                 mg/l or less 
                 5-25  
                 days 
                 When matured for more than 15 days, the effects of 
               
               
                   
                   
                   
                   
                   
                   
                 removing nitrate are exhibited 
               
               
                 27 
                 Carrot 
                 4  
                 mg/l or less 
                 5-20  
                 days 
                 When matured for 10 or more days, good effects of 
               
               
                   
                   
                   
                   
                   
                   
                 removing nitrate are exhibited. 
               
               
                 28 
                 Radish sprout 
                 7  
                 mg/l or less 
                 4-6  
                 days 
                 When matured for a long time, nitrate concentration  
               
               
                   
                   
                   
                   
                   
                   
                 may increase again. 
               
               
                 29 
                 Radish 
                 5  
                 mg/l or less 
                 8-15  
                 days 
                 When matured for more than 10 days, good effects of 
               
               
                   
                   
                   
                   
                   
                   
                 removing nitrate are exhibited. 
               
               
                 30 
                 Turnip 
                 5  
                 mg/l or less 
                 8-17  
                 days 
                 When matured for more than 10 days, good effects of 
               
               
                   
                   
                   
                   
                   
                   
                 removing nitrate are exhibited. 
               
               
                 31 
                 Broad bellflower 
                 6  
                 mg/l or less 
                 8-17  
                 days 
                 When matured for more than 12 days, good effects of  
               
               
                   
                   
                   
                   
                   
                   
                 removing nitrates are exhibited. 
               
               
                 32 
                 Green bean 
                 7  
                 mg/l or less 
                 5-15  
                 days 
                 When matured for a long time, it may decay (stalk part). 
               
               
                   
                 sprout 
                   
                   
                   
                   
                   
               
               
                 33 
                 Bean sprout 
                 7  
                 mg/l or less 
                 5-15  
                 days 
                 When matured for a long time, it may decay (stalk part). 
               
               
                 34 
                 Peanut 
                 5  
                 mg/l or less 
                 4-15  
                 days 
                 Up to 15 days, nitrate concentration does not increase 
               
               
                   
                   
                   
                   
                   
                   
                 again. 
               
               
                 35 
                 Mugwort 
                 8  
                 mg/l or less 
                 8-17  
                 days 
                 When matured for more than 10 days, the effects of  
               
               
                   
                   
                   
                   
                   
                   
                 removing nitrate are exhibited. 
               
               
                 36 
                 Pumpkin 
                 6  
                 mg/l or less 
                 7-15  
                 days 
                   
               
               
                 37 
                 Rosemary 
                 8  
                 mg/l or less 
                 8-17  
                 days 
                 The effects of removing nitrate are not hight, but it adds 
               
               
                   
                   
                   
                   
                   
                   
                 flavor when preparing salt. 
               
               
                 38 
                 Rose 
                 6  
                 mg/l or less 
                 8-17  
                 days 
                 The best effectts of removing nitrate among herb plants 
               
               
                 39 
                 Pine branch 
                 8  
                 mg/l or less 
                 15-30  
                 days 
                 When matured for a long time, the effects of removing 
               
               
                   
                   
                   
                   
                   
                   
                 nitrate are exhibited. 
               
               
                 40 
                 Pine needle 
                 8  
                 mg/l or less 
                 15-40  
                 days 
                 When matured for a long time, the effects of removing 
               
               
                   
                   
                   
                   
                   
                   
                 nitrate are exhibited. 
               
               
                 41 
                 Acanthopanax 
                 8-7  
                 mg/l 
                 8-30  
                 days 
                 When matured for a long time, the effects or removing  
               
               
                   
                   
                   
                   
                   
                   
                 nitrate are exhibited/easy to remove color by mixing 
               
               
                   
                   
                   
                   
                   
                   
                 with other plants 
               
               
                 42 
                 Chard 
                 10  
                 mg/l or less 
                 8-17  
                 days 
                 Nitrate concentration increases for the first 1 to 3 days, 
               
               
                   
                   
                   
                   
                   
                   
                 and then a little is removed after 7 days. 
               
               
                 43 
                 Ginseng shreds 
                 10  
                 mg/l or less 
                 5-10  
                 days 
                 High content of edible sulfur, but easily go bad. 
               
               
                 44 
                 Spring onion 
                 8  
                 mg/l or less 
                 8-17  
                 days 
                 High content of edible sulfur, but easily go bad. 
               
               
                   
                 (stalk and root) 
                   
                   
                   
                   
                   
               
               
                 45 
                 Wild rocambole 
                 9  
                 mg/l or less 
                 3-7  
                 days 
                 When matured for 10 or more days, nitrate concentration 
               
               
                   
                 leaf 
                   
                   
                   
                   
                 increases. 
               
               
                 46 
                 Wild rocambole 
                 9  
                 mg/l or less 
                 3-7  
                 days 
                 When matured for 10 or more days, nitrate concentration 
               
               
                   
                 root 
                   
                   
                   
                   
                 increases. 
               
               
                 47 
                 Broccoli 
                 6  
                 mg/l or less 
                 3-10  
                 days 
                 When matured for 25 or more days, nitrate 
               
               
                   
                   
                   
                   
                   
                   
                 concentration may increase. 
               
               
                 48 
                 Candle plant 
                 8-6  
                 mg/l or less 
                 3-20  
                 days 
                 The effects of removing nitrate are not high, but 
               
               
                   
                   
                   
                   
                   
                   
                 it adds flavor when preparing salt. 
               
               
                 49 
                 Pineapple sage 
                 8-5  
                 mg/l 
                 8-17  
                 days 
                 The effects of removing nitrate are not high, but 
               
               
                   
                   
                   
                   
                   
                   
                 it adds flavor when preparing salt. 
               
               
                 50 
                 Lemon balm 
                 8-6  
                 mg/l 
                 3-20  
                 days 
                 The effects of removing nitrate are not high, but 
               
               
                   
                   
                   
                   
                   
                   
                 it adds flavor when preparing salt. 
               
               
                 51 
                 Pineapple mint 
                 8-5 
                 mg/l 
                 3-20  
                 days 
                 The effects of removing nitrate are not high, but 
               
               
                   
                   
                   
                   
                   
                   
                 it adds flavor when preparing salt. 
               
               
                 52 
                 Green tea leaf 
                 8-5  
                 mg/l 
                 3-20  
                 days 
                 The effects of removing nitrate are not high, but 
               
               
                   
                   
                   
                   
                   
                   
                 it adds flavor when preparing salt. 
               
               
                 53 
                 Apple mint 
                 8-6  
                 mg/l 
                 3-20  
                 days 
                 The effects of removing nitrate are not high, but 
               
               
                   
                   
                   
                   
                   
                   
                 it adds flavor when preparing salt. 
               
               
                 54 
                 Mustard leaf 
                 9-6  
                 mg/l 
                 5-15  
                 days 
                 Brassicaceae, but removes nitrate slightly. 
               
               
                 55 
                 Green tea leaf 
                 8-6  
                 mg/l 
                   
                   
                   
               
               
                 56 
                 Cabbage 
                 3  
                 mg/l or less 
                 10 
                 days 
                   
               
               
                 57 
                 Red cabbage 
                 2  
                 mg/l or less 
                 10  
                 days 
                   
               
               
                   
               
             
          
         
       
     
         [0124]    As shown in Table 2 above, 
         [0125]    All the experimented plants exhibited the power of removing nitrate. Hence, when removing nitrate by using such plants, the nitrate-minimized salt water and salt may be prepared. Further, salt water and salt having the plant&#39;s unique flavor (taste and smell) may be prepared. 
       Third embodiment: Preparation of Nitrate-Minimized Salt 
       [0126]    Salt water, which is prepared in no. 1 (bamboo shoot is used as the plant containing edible sulfur) of the second embodiment, is heated to 90 to 100° C., and water is evaporated within 2 minutes so as to prepare fine salt. In order to measure the amount of nitrate contained in the prepared salt, prepared salt 1 g is melted in distilled water 300 ml, and then the content of nitrate was measured by using Test No. 3 measuring kit of Tetra company (Germany, www.tetra.net) As a result, the content of nitrate was 1.3 mg/100 g. 
       Fourth Embodiment: Measuring Content of Sodium and Content of Edible Sulfur of Prepared Salt 
       [0127]    (1) Measuring Content of Sodium 
         [0128]    Content of sodium, which is contained is salt prepared in the third embodiment, was measured by the sodium electron ion measuring scheme. That is, bay salt 100 g, which was purchased, and salt 100 mg, which was prepared in the third embodiment, were respectively melted in distilled water 100 ml so as to prepare a salt solution, and the content of sodium contained in each salt solution was measured in normal temperatures according to the sodium electron ion measuring scheme. 
         [0129]    As a result of the experiment, it was confirmed that sodium was less contained by 13 mg to 15 mg/L in the salt solution which was prepared in the third embodiment, compared to the salt solution which was prepared by bay salt which was purchased in the market. This shows that sodium has been consumed by halophilic bacteria in the process of preparing sodium. 
         [0130]    (2) Measuring Content of Edible Sulfur 
         [0131]    The content of edible sulfur, which was contained in the salt prepared in the third embodiment, was measured by the sulfur icon electrode measuring scheme. As a result, it was found that about edible sulfur 1000 mg were contained in salt 50 g. 
         [0132]    (3) Checking Relation between the Content of Edible Sulfur and Salty Taste 
         [0133]    The relation between the content of edible sulfur and salty taste was checked with 20 testees. The testees include 13 women in 30s and 7 men in forties. The testees tasted salts having various contents of edible sulfur and evaluated and recorded the level of salty taste. 
         [0134]    As a result, 12 persons felt that the salty taste was reinforced when 500 mg or more edible sulfur were contained per 50 g salt, and when 1500 mg was contained, 16 felt that the salty tasted was more than doubled. 
       Fifth Embodiment: Identifying Sulfation Bacteria 
       [0135]    Bacteria contained in root pieces of bacteria-transplanted  Sasa borealis  in 2) of (1) of the second embodiment were identified with the temperature gradient gel electrophoresis (TGGE) method, and the result photograph is shown in  FIG. 1 . Further, each DNA band is cut, extracted, and refined, and is then amplified. Then the DNA sequence is analyzed through a specialized company, then the bacteria were identified based on the database of GenBank by using the result. 
         [0136]    As a result of the identification, it was found that the salt water contains  Marinobacter  sp.(GenBank accession number JQ618280),  Marispirillum indicum  (GenBank accession number NR044545),  Thalassospira  sp.(GenBank accession number AB373113),  Caminibacillus  (GenBank accession number AB752312),  Tepidibacter formici  genes (GenBank accession number JQ670743),  Geosporobacter subterraneus  (GenBank accession number DQ643978), and  Firmicutes bacterium  (GenBank accession number JX240960)