Bactericide containing iron ions

Pathogenic bacteria have long posed a threat to mankind, and it has been a goal in the food industry and the medical profession to develop a bactericide that would have a high degree of practicality which included spores in its scope, that would exhibit a pronounced effect on pathogenic bacteria, that would be safe for humans and the earth, and that would be composed of metal ions having affinity with the body, that is, those which are essential structural components for the body, and compounds that are used in food additives. Provided are a bactericide containing ferric ions (Fe.sup.3+) and one or more members of the group consisting of sorbic acid, benzoic acid, and para-hydroxybenzoic acid esters; a bactericide containing ferric ions (Fe.sup.3+), L-ascorbic acid, and one or more members of the group consisting of sorbic acid, benzoic acid, and para-hydroxybenzoic acid esters; and a bactericide containing ferric ions (Fe.sup.3+), sorbic acid, benzoic acid, and L-ascorbic acid. As a result, the major pathogenic bacteria can be eradicated in a short time, and the bactericide is highly stable.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a bactericide containing ferric ions
 (Fe.sup.3+) and one or more members of the group consisting of sorbic
 acid, benzoic acid, and para-hydroxybenzoic acid esters, and to a
 bactericide containing ferric ions (Fe.sup.3+), L-ascorbic acid, and one
 or more members of the group consisting of sorbic acid, benzoic acid, and
 para-hydroxybenzoic acid esters, which can be used in a wide range of
 applications, from the sterilization of hands and wounds, to the
 sterilization of furniture, tools, and objects, to the sterilization of
 fresh foods prior to cooking.
 2. Description of the Related Art
 Despite the sophisticated roadway system and communication network, huge
 budgets, numerous CDC (Center for Disease Control) personnel, and
 state-of-the-art medical treatment available in a developed country like
 the United States, and even though it has been 16 years since the
 discovery of Escherichia coli O-157, there are still more than 20,000 new
 patients each year, and over 200 deaths. In Japan as well, there were
 numerous mass infections in 1996, and at the present time the situation is
 still far from static, to the extent that there are researchers who say
 that this O-157 is a "microbe" that can survive anywhere in the
 environment and causes infection at a very low bacterium count, and
 furthermore it is a known fact that there is no way to halt the onslaught
 of tubercule bacilli or staphylococci with resistance to multiple drugs.
 Moreover, in developing countries, oral infectious diseases such as
 dysentery and cholera are as rampant as ever, and respiratory infectious
 diseases such as tuberculosis are also widespread. There are currently
 twenty million patients with tuberculosis in the world, and while most of
 these are in Africa and other developing countries, there are eight
 million new cases each year, and the annual number of deaths is said to be
 in excess of three million. While ignorance about infectious diseases and
 poor public sanitation cannot be overlooked, these facts are probably also
 attributable to the fact that people have no antiseptic that allows
 instantaneous disinfection and is very safe.
 Of the sterilization and disinfection methods in daily use today, alcohols,
 phenols, halogen compounds, quaternary ammonium salts, biguanide-based
 chemicals, aldehydes, and the like have been put to practical use as
 chemical methods, aside from such physical methods as heat and radiation.
 However, there is no product that is satisfactory in all respects, such as
 a good bactericidal effect, safety, low toxicity, excellent stability and
 shelf life, and low price. For instance, a biguanide-based chemical sold
 under the trade name Hibitane is an excellent, best-selling antiseptic,
 but it is ineffective against spores. Also, resistance has been noted in
 some bacteria, and this is known to be a cause of hospital acquired
 infection. There is no need to mention antibiotics, and as for chemical
 synthetics that are discomforting to microbial cells, resistant strains
 that render these ineffective always appear as a result of the production
 of enzymes or the production of substitute enzymes, and these are once
 again showing up as a threat to humans.
 It is already known that certain types of metal ions have a bactericidal
 action over a specific concentration, and these have been applied in
 mercury preparations and the like. Mercury, however, is a heavy metal that
 is completely unnecessary in the body, and furthermore it is extremely
 toxic, so it has yielded its position as an antiseptic as the various
 antiseptics mentioned above have been developed, and ever since then
 antiseptics that make use of metal ions have been virtually ignored. More
 recently, metal elements have been recognized as essential substances in
 the body, and their dark image, first as poisons or alchemy and then as
 environmental pollutants in more recent years, has been swept away, until
 they are now considered one of the important elements that protect our
 health, with various minerals and tablets containing these being crowded
 together with foodstuffs in American supermarkets and the like.
 Various metal ions were tested for their bactericidal effect on the major
 pathogenic bacteria, with the upper limit of the metal ion concentration
 set at 1000 ppm and the concentration set so as to exhibit the highest
 efficacy. The test method involved adding a suspension of sample bacteria
 (1.times.10.sup.9 cells/mL physiological saline) in an amount of 2 wt % to
 a metal ion solution, allowing 60 minutes for the contact time with the
 bacteria, sampling 10 .mu.L of the treated liquid, culturing the samples
 in the optimal environment for each type of bacteria, and observing the
 viability of the bacteria. As a result, the same efficacy was exhibited,
 with the exception of spore forming bacteria. For the test, methicillin
 resistant Staphylococcus aureus (MRSA) was selected from among
 staphylococci as a typical Gram-positive bacterium, and Escherichia coli
 O-157 was selected from among Escherichia coli as a typical Gram-negative
 bacterium. These test results are given in Table 1. As is seen in Table 1,
 bactericidal action was noted for cupric ions (CU.sup.2+) and ferric ions
 (Fe.sup.3+). Viability of the bacteria was expressed as ++ when the
 bacteria proliferated normally with no impediment whatsoever, as + when
 they were damaged and their proliferation was somewhat inhibited, as .+-.
 when they were damaged and their proliferation was inhibited, and as -
 when they did not proliferate and were eradicated.
 TABLE 1
 Bactericidal action of various metal ions
 Metal Viability
 ion Compound name MRSA O-157
 Cu.sup.2+ CuSO.sub.4.5H.sub.2 O - -
 Zn.sup.2+ ZnSO.sub.4.7H.sub.2 O + -
 Mn.sup.2+ MnSO.sub.4.5H.sub.2 O ++ ++
 Co.sup.2+ CoCl.sub.2.2H.sub.2 O ++ ++
 Ni.sup.2+ NiSO.sub.4.6H.sub.2 O + +
 Li.sup.+ Li.sub.2 SO.sub.4.H.sub.2 O ++ ++
 Ca.sup.3+ CaCl.sub.2.2H.sub.2 O ++ ++
 Mg.sup.2+ MgSO.sub.4.7H.sub.2 O ++ ++
 Si.sup.4+ SiO.sub.2 ++ ++
 Rb.sup.+ Rb.sub.2 SO.sub.4 ++ ++
 Al.sup.3+ Al.sub.2 (SO.sub.4).sub.2.12H.sub.2 O + +
 Fe.sup.2+ FeCl.sub.2 + +
 FeCl.sub.2.4H.sub.2 O + +
 Fe(CH.sub.3 CHOHCOO).sub.2.3H.sub.2 O + +
 FeC.sub.2 O.sub.4.2H.sub.2 O + +
 FeSO.sub.4.7H.sub.2 O + +
 Fe.sup.3+ FeCl.sub.3 - -
 FeCl.sub.3.6H.sub.2 O - -
 Fe(NO.sub.3).sub.3.9H.sub.2 O - -
 Fe.sub.2 (SO.sub.4).sub.3.nH.sub.2 O - -
 FeC.sub.6 H.sub.5 O.sub.7.nH.sub.2 O - -
 FePO.sub.4.nH.sub.2 O - -
 Next, if we examine the relation between concentration and bacterium
 contact time for the bactericidal effect of ferric ions (Fe.sup.3+), we
 see that an effect is gradually exhibited from 400 ppm upward, as shown in
 Table 2, and at 1000 ppm an effect is exhibited at a bacterium contact
 time of 5 minutes. The viability of the bacteria was evaluated the same as
 in Table 1.
 TABLE 2
 Bactericidal action of ferric ions (Fe.sup.3+)
 Concentration Contact time Viability
 as Fe.sup.3+ (ppm) with bacteria MRSA O-157
 100 10 seconds ++ ++
 1 minute ++ ++
 5 minutes ++ ++
 200 10 seconds ++ ++
 1 minute ++ ++
 5 minutes ++ ++
 400 10 seconds ++ ++
 1 minute ++ ++
 5 minutes + .+-.
 800 10 seconds + +
 1 minute + .+-.
 5 minutes .+-. -
 1000 10 seconds + .+-.
 1 minute + .+-.
 5 minutes .+-. -
 Meanwhile, the bactericidal action of sorbic acid, calcium sorbate, benzoic
 acid, sodium benzoate, and other such compounds known as food
 preservatives was examined. The concentration was 1000 ppm, and the
 contact time with the bacteria was 5 to 120 minutes, after which 10 .mu.L
 of treated liquid was sampled and cultured in the optimal environment for
 each type of bacteria, and the viability of the bacteria was observed. As
 shown in Table 3, the test results for methicillin resistant
 Staphylococcus aureus (MRSA) and Escherichia coli O-157 indicated no
 bactericidal action in a short time, and when the contact time was
 extended to between 30 and 60 minutes, there was finally a bacteriostatic
 action or bacterial action. Viability of the bacteria was expressed as ++
 when the bacteria proliferated normally with no impediment whatsoever, as
 + when they were damaged and their proliferation was somewhat inhibited,
 as .+-. when they were damaged and their proliferation was inhibited, as
 (-) when the coloring of the bacteriostatic action was darker than that of
 the bactericidal action, and as - when they did not proliferate and were
 eradicated.
 TABLE 3
 Bactericidal action of food preservatives
 Food Contact time Viability
 preservative with bacteria MRSA O-157
 sorbic acid 5 minutes ++ +
 15 + +
 30 (-) (-)
 60 (-) (-)
 120 (-) (-)
 calcium 5 minutes ++ ++
 sorbate 15 + +
 30 .+-. (-)
 60 (-) (-)
 120 (-) (-)
 benzoic acid 5 minutes ++ ++
 15 + +
 30 (-) (-)
 60 (-) (-)
 120 (-) (-)
 sodium 5 minutes ++ ++
 benzoate 15 + +
 30 .+-. .+-.
 60 (-) (-)
 120 (-) (-)
 Pathogenic bacteria have long posed a threat to mankind, and it has been a
 goal in the food industry and the medical profession to develop a
 bactericide that would have a high degree of practicality which included
 spores in its scope, that would exhibit a pronounced effect on pathogenic
 bacteria, that would be safe for humans and the earth, and that would be
 composed of metal ions having affinity with the body, that is, those which
 are essential structural components for the body, and compounds that are
 used in food additives.
 SUMMARY OF THE INVENTION
 As a result of obtaining as many different water-soluble compounds of metal
 ions as possible, with the exception of harmful heavy metals that are
 unnecessary in the body, and investigating the bactericidal effect
 thereof, the inventors arrived at providing a metal ion-containing
 bactericide. Specifically, this is a bactericide containing ferric ions
 (Fe.sup.3+) and one or more members of the group consisting of sorbic
 acid, benzoic acid, and para-hydroxybenzoic acid esters. It is preferable
 for the concentration of ferric ions (Fe.sup.3+) to be 500 to 1500 ppm,
 and it is also preferable for the concentration of the one or more members
 of the group consisting of sorbic acid, benzoic acid, and
 para-hydroxybenzoic acid esters to be 200 to 2000 ppm.
 The second present invention is a bactericide containing ferric ions
 (Fe.sup.3+), L-ascorbic acid, and one or more members of the group
 consisting of sorbic acid, benzoic acid, and para-hydroxybenzoic acid
 esters. It is preferable for the concentration of ferric ions (Fe.sup.3+)
 to be 500 to 1500 ppm, it is preferable for the concentration of
 L-ascorbic acid to be 500 to 2000 ppm, and it is also preferable for the
 concentration of the one or more members of the group consisting of sorbic
 acid, benzoic acid, and para-hydroxybenzoic acid esters to be 200 to 2000
 ppm.
 The third present invention is a bactericide containing ferric ions
 (Fe.sup.3+), sorbic acid, benzoic acid, and L-ascorbic acid. It is
 preferable for the concentration of the ferric ions (Fe.sup.3+) to be 500
 to 1500 ppm, the concentration of the sorbic acid and benzoic acid to be
 200 to 2000 ppm, and the concentration of the L-ascorbic acid to be 500 to
 2000 ppm.

Key:
 1: Change in the bactericidal strength of the iron ion-containing
 bactericide of the present invention
 2: Change in the bactericidal strength of a conventional antiseptic
 DESCRIPTION OF THE PREFERRED EMBODIMENTS
 The phrase "ferric ions (Fe.sup.3+)" used in the present invention means
 that Fe.sup.3+ ions are present in a solution, which can be obtained, for
 example, by dissolving ferric chloride, ferric chloride hexahydrate,
 ferric nitrate, ferric nitrate hexahydrate, ferric nitrate nonahydrate,
 ferric sulfate n-hydrate, ferric phosphate n-hydrate, ferric citrate
 n-hydrate, or the like in water.
 The sorbic acid referred to in the present invention is not only sorbic
 acid itself, but also includes sorbates, examples of which include
 potassium sorbate and sodium sorbate.
 The benzoic acid referred to in the present invention is not only benzoic
 acid itself, but also includes benzoates, examples of which include
 potassium benzoate, sodium benzoate, calcium benzoate, ammonium benzoate,
 and zinc benzoate.
 The para-hydroxybenzoic acid ester referred to in the present invention is
 an ester of para-hydroxybenzoic acid and an alcohol, examples of which
 include methyl para-hydroxybenzoate, ethyl para-hydroxybenzoate, butyl
 para-hydroxybenzoate, and propyl para-hydroxybenzoate.
 The pathogenic bacteria referred to in the present invention are microbes
 that are the cause of disease, such as bacteria or viruses to cause
 enteric canal infection, respiratory organ infection, ureter infection,
 etc. Examples of bacteria that cause various infectious diseases include
 Salmonella spp., Shigella spp., Vibrio parahaemolyticus, Vibrio choreae,
 Escherichia coli O-157, Campylobacter jejuni, Clostridium difficile,
 Clostridium perfringens, Yersinia enterocolitica, Heliobacter pylori,
 Entemoea histolytica, Bacillus cereus, Staphylococcus spp., Clostridium
 botulinum, Haemophilus influenzae, Streptococcus pneumoniae, Chlamidia
 pneumoniae, Legionella pneumoniae, Branhamella catarrhalis, Mycobacterium
 tuberculosis, Mycoplasma pneumoniae, Streptococcus pyogenes,
 Corynebacterium diphtheriae, Bordetella pertussis, Chlamidia psittaci,
 Pseudomonas aerginosa, methicillin resistant Staphylococcus aureus (MRSA),
 Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., Proteus spp.,
 Acinetobacter spp., Enterococcus faecalis, Staphylococcus saprophyticus,
 and Streptococcus agalactiae.
 Antisepsis as used in the present invention means eradicating pathogenic
 bacteria, and is not concerned with the survival of non-pathogenic
 microorganisms. In this respect, disinfection means completely killing all
 microorganisms, not just pathogenic microorganisms. Therefore, an
 antiseptic refers to a chemical substance when sterilization is performed
 with this chemical substance.
 The mechanism of action of the iron ion-containing bactericide of the
 present invention is not fully understood as yet, but is believed to be as
 follows. Iron is an essential substance for all organisms, and the iron in
 food is present in the form of inorganic iron (a complex in which ferric
 ions are bonded to an amino acid or a peptide), heme iron bonded to animal
 protein, or nonheme iron bonded to vegetable protein. This iron bonds with
 as many as 200 different types of enzymes in the body and supports vital
 activities. It is also responsible for O.sub.2 transport as the main
 component of hemoglobin. Thus, ferric ions (Fe.sup.3+) is an active form
 that is far more powerful in the body than ferrous ions (Fe.sup.2+), and
 also has more powerful oxidation. In higher organisms, iron undergoes
 orderly bonding with predetermined enzymes under command, but in
 single-celled organisms, the osmotic action is further increased by the
 above-mentioned fortifiers or the like, quickly penetrating into the cell
 from the outside, and the filling Fe.sup.3+ ions can eventually upset the
 system, bonding to enzymes and proteins in an avalanche, which can be
 fatal to a bacterium. The powerful oxidizing action thereof is also
 thought to destroy cellular walls and the like in an extremely short time,
 as if they were being attacked.
 The bactericidal strength of the iron ion-containing bactericide of the
 present invention can be enhanced by the addition of a minute amount of
 cupric ions (Cu.sup.2+), zinc ions (Zn.sup.2 e), an extract containing any
 of various metal ions and having mica as a raw material, an antibiotic
 substance derived from any of various plants (specifically, a substance
 called a phytoncide; the essential oils of plants primarily correspond to
 this, such as tea tree oil, thymol, camphor, clove, chamomile, eucalyptus,
 oregano, and other such essential oils), a plant extract containing any of
 various minerals, a surfactant, or the like.
 EXAMPLES
 The iron ion-containing bactericide of the present invention is produced by
 dissolving a compound composed of ferric ions (Fe.sup.3+) in water and
 then preparing a solution of benzoic acid or a benzoate. Also, sorbic acid
 or a sorbate is dissolved in water to prepare an aqueous solution of
 sorbic acid. Meanwhile, L-ascorbic acid is dissolved in water to prepare
 an aqueous solution of L-ascorbic acid. These aqueous solutions are mixed
 as dictated by the composition of the bactericide to manufacture an iron
 ion-containing bactericide. The present invention will now be described in
 further detail through examples, but the gist of the present invention is
 not limited to or by these examples.
 Example 1
 For ferric chloride hexahydrate (FeCl.sub.3.6H.sub.2 O) as the ferric ions
 (Fe.sup.3+), methicillin resistant Staphylococcus aureus (MRSA) was
 selected from among staphylococci, Escherichia coli O-157 was selected
 from among Escherichia coli, the concentration of ferric ions (Fe.sup.3+)
 was set between 500 and 2000 ppm, the concentrations of sorbic acid or
 benzoic acid were set between 100 and 2500 ppm, and the bacterium contact
 time was set between 10 seconds and 5 minutes, after which the
 bactericidal action was tested. The test method involved adding a
 suspension of sample bacteria (1.times.10.sup.9 cells/mL physiological
 saline) in an amount of 2 wt % to an iron ion-containing bactericide,
 allowing a specific amount of time for contact with the bacteria, sampling
 10 .mu.L of the treated liquid, culturing the sample in the optimal
 environment for each type of bacteria, and observing the viability of the
 bacteria. These results are given in Tables 4 and 5, which show that both
 MRSA and E. coli O-157 were eradicated at a contact time of only 10
 seconds with a mixed liquid having an ferric ion (Fe.sup.3+) concentration
 of 1000 ppm and a sorbic acid concentration of 1000 ppm. A similar
 bactericidal effect was obtained with potassium sorbate, benzoic acid, and
 sodium benzoate. Viability of the bacteria was expressed as ++ when the
 bacteria proliferated normally with no impediment whatsoever, as + when
 they were damaged and their proliferation was somewhat inhibited, as .+-.
 when they were damaged and their proliferation was inhibited, and as -
 when they did not proliferate and were eradicated.
 TABLE 4
 Bactericidal action using both ferric ions (Fe.sup.3+)
 and food preservatives (1)
 Food preservative Viability
 Concen. Com- MRSA 0-157
 as Fe.sup.3+ pound Concen. 10 1 5 10 1 5
 (ppm) name (ppm) sec* min* min* sec* min* min*
 500 potassium 100 ++ ++ + ++ ++ +
 sorbate 200 ++ + .+-. ++ + .+-.
 500 ++ + .+-. ++ + .+-.
 1000 ++ + .+-. ++ + -
 1500 ++ + - ++ .+-. -
 2000 ++ .+-. - ++ .+-. -
 2500 ++ .+-. - ++ .+-. -
 sodium 100 ++ ++ + ++ ++ +
 benzoate 200 ++ + + ++ + .+-.
 500 ++ + .+-. ++ + .+-.
 1000 ++ + .+-. ++ + -
 1500 ++ + - ++ + -
 2000 ++ .+-. - ++ .+-. -
 2500 ++ .+-. - ++ .+-. -
 1000 potassium 100 + .+-. + .+-. + -
 sorbate 200 + .+-. - + .+-. -
 500 .+-. - - .+-. - -
 1000 - - - - - -
 1500 - - - - - -
 2000 - - - - - -
 2500 - - - - - -
 sodium 100 + + .+-. + .+-. -
 benzoate 200 + .+-. - .+-. .+-. -
 500 .+-. - - .+-. - -
 1000 - - - .+-. - -
 1500 - - - - - -
 2000 - - - - - -
 2500 - - - - - -
 sorbic acid 100 + + .+-. + .+-. -
 200 + .+-. - + .+-. -
 500 .+-. - - .+-. - -
 1000 - - - - - -
 1500 - - - - - -
 2000 - - - - - -
 2500 - - - - - -
 *Contact time with bactericide.
 TABLE 5
 Bactericidal action using both ferric ions (Fe.sup.3+)
 and food preservatives (2)
 Food preservative Viability
 Concen. Com- MRSA 0-157
 as Fe.sup.3+ pound Concen. 10 1 5 10 1 5
 (ppm) name (ppm) sec* min* min* sec* min* min*
 1500 potassium 100 + .+-. .+-. + .+-. -
 sorbate 200 + .+-. - + .+-. -
 500 .+-. - - - - -
 1000 - - - - - -
 1500 - - - - - -
 2000 - - - - - -
 2500 - - - - - -
 sodium 100 + .+-. .+-. + .+-. -
 benzoate 200 + .+-. - + .+-. -
 500 .+-. - - .+-. - -
 1000 - - - - - -
 1500 - - - - - -
 2000 - - - - - -
 2500 - - - - - -
 benzoic 100 + .+-. .+-. + .+-. -
 acid 200 + .+-. - + .+-. -
 500 .+-. - - .+-. - -
 1000 - - - - - -
 1500 - - - - - -
 2000 - - - - - -
 2500 - - - - - -
 2000 sodium 100 + .+-. .+-. + .+-. -
 sorbate 200 + .+-. - + .+-. -
 500 .+-. - - .+-. - -
 1000 - - - - - -
 1500 - - - - - -
 2000 - - - - - -
 2500 - - - - - -
 sodium 100 + .+-. .+-. + .+-. -
 benzoate 200 + .+-. .+-. .+-. .+-. -
 500 .+-. - - .+-. - -
 1000 - - - - - -
 1500 - - - - - -
 2000 - - - - - -
 2500 - - - - - -
 *Contact time with bactericide.
 Example 2
 For ferric chloride hexahydrate as the ferric ions (Fe.sup.3+), just as in
 Example 1, methicillin resistant Staphylococcus aureus (MRSA) and
 Escherichia coli O-157 were selected, the concentration of ferric ions
 (Fe.sup.3+) was set at 1000 ppm, the concentrations of sorbic acid or
 benzoic acid were set between 50 and 500 ppm, and the bacterium contact
 time was set between 10 seconds and 5 minutes, after which the
 bactericidal action was tested. The test was conducted in the same manner
 as in Example 1, and the viability of the bacteria was observed. These
 results are given in Table 6, which shows that an excellent bactericidal
 effect is exhibited when the ferric ion (Fe.sup.3+) concentration is at
 least 500 ppm, and preferably 500 to 1500 ppm, and the sorbic acid and
 benzoic acid are contained, either alone or combined, in an amount of at
 least 200 ppm, and preferably 200 to 2000 ppm.
 TABLE 6
 Bactericidal action using both ferric ions (Fe.sup.3+)
 and food preservatives (3)
 Food preservative
 combination Viability
 Concen. Com- MRSA 0-157
 as Fe.sup.3+ pound Concen. 10 1 5 10 1 5
 (ppm) name (ppm) sec* min* min* sec* min* min*
 1000 potassium 50 + + - + .+-. -
 sorbate
 sodium 50
 benzoate
 potassium 100 + .+-. - + .+-. -
 sorbate
 sodium 100
 benzoate
 potassium 50 + .+-. - + .+-. -
 sorbate
 sodium 50
 benzoate
 sorbic acid 100
 potassium 200 .+-. - - .+-. - -
 sorbate
 sodium 300
 benzoate
 potassium 200 - - - - - -
 sorbate
 sodium 300
 benzoate
 sorbic acid 500
 potassium 250 - - - - - -
 sorbate
 sodium 250
 benzoate
 sorbic acid 250
 benzoic 250
 acid
 *Contact time with bactericide.
 Comparative Example 1
 Using ferrous chloride and ferrous sulfate heptahydrate as ferrous ions
 (Fe.sup.2+) instead of the ferric chloride hexahydrate used in Example 1,
 methicillin resistant Staphylococcus aureus (MRSA) and Escherichia coli
 O-157 were selected, the concentration of ferrous ions (Fe.sup.2+) was set
 at 1000 ppm, the concentrations of sorbic acid or benzoic acid were set at
 1000 ppm, and the bacterium contact time was set between 10 and 30
 minutes, after which the bactericidal action was tested. The test was
 conducted in the same manner as in Example 1, and the viability of the
 bacteria was observed. These results are given in Table 7, which shows
 that even sorbic acid or benzoic acid was added, when the ferrous ion
 (Fe.sup.2+3) concentration was 1000 ppm, neither the MRSA nor the E. coli
 O-157 was erradicated within a contact time of 20 minutes.
 TABLE 7
 Bactericidal action of ferrous ions (Fe.sup.2+)
 Fe.sup.2+ Food
 compound name preservative
 (concen. as name (concen.: Contact time Viability
 Fe.sup.2+ : 1000 ppm) 1000 ppm) with bacteria MRSA O-157
 Ferrous none added 10 ++ ++
 chloride 20 ++ ++
 (FeCl.sub.2) 30 ++ ++
 potassium sorbate 10 ++ ++
 20 + .+-.
 30 - -
 sodium benzoate 10 ++ ++
 20 + .+-.
 30 (-) -
 Ferrous none added 10 ++ ++
 sulfate 20 ++ ++
 (FeSO.sub.4.7H.sub.2 O) 30 ++ ++
 potassium sorbate 10 ++ ++
 20 + .+-.
 30 - -
 sodium benzoate 10 ++ ++
 20 + .+-.
 30 (-) -
 Comparative Example 2
 Bactericidal action was tested by the same method as in Example 1 for
 carbolic acid, aqueous hydrogen peroxide, and a Hibitane solution
 containing 5% chlorhexidine gluconate (C.sub.22 H.sub.30
 ClN.sub.10.2C.sub.6 H.sub.12 O.sub.7). These results are given in Table 8,
 which shows that a bactericidal effect is not exhibited at a bacterium
 contact time of 10 seconds even at a high concentration of 30,000 ppm.
 TABLE 8
 Bactericidal action of antiseptics
 Contact time Viability
 Antiseptic (ppm) with bacteria MRSA O-157
 Carbolic acid
 3000 10 sec ++ ++
 1 min ++ ++
 5 min ++ ++
 10,000 10 sec ++ ++
 1 min ++ ++
 5 min + +
 30,000 10 sec .+-. .+-.
 1 min - -
 5 min - -
 Aqueous hydrogen peroxide
 3000 10 sec ++ ++
 1 min ++ ++
 5 min + -
 10,000 10 sec + ++
 1 min .+-. .+-.
 5 min - -
 30,000 10 sec .+-. +
 1 min - -
 5 min - -
 Hibitane solution
 3000 10 sec ++ ++
 1 min ++ ++
 5 min + +
 10,000 10 sec ++ ++
 1 min + +
 5 min .+-. .+-.
 30,000 10 sec + +
 1 min - -
 5 min - -
 Example 3
 An aqueous solution of ferric chloride hexahydrate with a concentration of
 2000 ppm as Fe.sup.3+ was prepared, then an aqueous solution of 2000 ppm
 potassium sorbate was made, and these aqueous solutions were mixed in
 amounts of 1 liter each to prepare 2 liters of bactericide containing iron
 ions. This solution therefore contained 1000 ppm each of Fe.sup.3+ and
 potassium sorbate. Daikon [white radish] sprouts to which numerous E. coli
 O-157 had adhered was dipped in this 2 L solution and left for 1 hour,
 after which the radish sprouts and the used bactericide were checked for
 E. coli O-157, but no bacteria could be detected.
 Example 4
 5 g of ferric sulfate [Fe.sub.2 (SO.sub.4).sub.3.nH.sub.2 O)] and 1 g of
 sodium benzoate were dissolved in 1 L of water Fe.sup.3+.apprxeq.1000 ppm;
 sodium benzoate=1000 ppm) to prepare a bactericide containing iron ions.
 The hands of a test subject were thoroughly washed with this bactericide
 for 10 seconds, after which the hands were tested for bacteria, but
 nothing was detected other than spores of the Bacillus genus.
 Example 5
 L-ascorbic acid was added to an iron ion-containing bactericide of ferric
 chloride hexahydrate and potassium sorbate and to an iron ion-containing
 bactericide of ferric chloride hexahydrate and sodium benzoate, and the
 time it took to eradicate spores was tested for 50 species of spores from
 the Bacillus genus and 50 species of spores from the Clostridium genus.
 The effect of a surfactant was also examined at this time. Here, solution
 A contained 1000 ppm (as Fe.sup.3+) ferric chloride and 500 ppm potassium
 sorbate; solution B contained 1000 ppm (as Fe.sup.3+) ferric chloride and
 500 ppm sodium benzoate; solution C contained 1000 ppm (as Fe.sup.3+)
 ferric chloride, 500 ppm potassium sorbate, and 1000 ppm ascorbic acid;
 solution D contained 1000 ppm (as Fe.sup.3+) ferric chloride, 500 ppm
 sodium benzoate, and 1000 ppm ascorbic acid; solution E contained 1000 ppm
 (as Fe.sup.3) ferric chloride, 500 ppm potassium sorbate, 1000 ppm
 ascorbic acid, and 100 ppm sodium laurylsulfate; and solution F contained
 1000 ppm (as Fe.sup.3+) ferric chloride, 500 ppm potassium sorbate, 1000
 ppm ascorbic acid, and 50 ppm tea tree oil. These results are given in
 Table 9, which shows that the eradication of spores did not go over 50%
 even after 120 minutes of bacterium contact with the bactericides to which
 no L-ascorbic acid was added. However, with the bactericides to which
 L-ascorbic acid was added, there were spores that were eradicated at a
 bacterium contact time of 5 minutes, 92 to 98% of the spores were
 eradicated after 120 minutes of contact, and when a small amount of
 surfactant was added, there were bacteria that were eradicated after
 contact of only 1 minute, and all of the spores had been eradicated by 120
 minutes of contact. Meanwhile, with the Hibitane solution used in the
 past, there were no spores eradicated even after 120 minutes of contact,
 and only 20 to 24% of the spores were eradicated by aqueous hydrogen
 peroxide.
 TABLE 9
 Time required for bacteria to die,
 and proportion thereof
 Bacillus spores, 50 species Clostridium spores, 50
 species
 10 1 5 30 60 120 10 1 5 30
 60 120
 sec min min min min min sec min min min
 min min
 Pres- A 0 0 4 20 40 50% 0 0 6 16
 30 40%
 ent B 0 0 4 18 36 44% 0 0 6 14
 26 34%
 inven- C 0 0 12 38 72 98% 0 0 14 32
 50 96%
 tion D 0 0 12 34 68 92% 0 0 12 38
 46 92%
 bac- E 0 4 26 72 90 100% 0 2 20 52
 72 100%
 teri- F 0 2 12 42 80 100% 0 6 18 48
 76 100%
 cide
 Ordi- Hibi- 0 0 0 0 0 O% 0 0 0 0
 0 0%
 nary tane
 bac- H.sub.2 O.sub.2 0 0 0 2 10 20% 0 0
 0 4 12 24%
 teri-
 cide
 Example 6
 An aqueous solution of ferric chloride (FeCl.sub.3) with a concentration of
 2400 ppm as Fe.sup.3+, an aqueous solution of L-ascorbic acid with a
 concentration of 3000 ppm, and an aqueous solution of sorbic acid with a
 concentration of 600 ppm were prepared, and these three types of aqueous
 solution were mixed in equal amounts to prepare a bactericide containing
 iron ions. 0.1 g of sodium laurate was added to 1 L of this bactericide. A
 dinner plate to which leftover food had adhered and which had been allowed
 to stand overnight was lightly washed as usual with this bactericide,
 whereupon the food came right off, without any neutral detergent, and
 furthermore no bacteria were detected on the plate.
 Example 7
 An aqueous solution of ferric chloride hexahydrate with a concentration of
 3000 ppm as Fe.sup.3+, an aqueous solution of L-ascorbic acid with a
 concentration of 2400 ppm, and an aqueous solution of sorbic acid with a
 concentration of 1500 ppm were prepared, and these three types of aqueous
 solution were mixed in equal amounts to prepare a bactericide containing
 iron ions. A rotting piece of pork was dipped in this bactericide for 1
 minute, after which the liquid was thoroughly wiped off with a piece of
 sterile gauze and applied to an agar culture medium. This was cultured at
 28.degree. C. and 37.degree. C., whereupon no bacteria proliferated in
 either medium, and it was confirmed that all of the countless putrefying
 bacteria that had been proliferating on the pork were eradicated in just
 one minute.
 Example 8
 An aqueous solution of ferric nitrate nonahydrate
 [Fe(NO.sub.3).sub.3.9H.sub.2 O)] with a concentration of 3000 ppm as
 Fe.sup.3+, an aqueous solution of L-ascorbic acid with a concentration of
 3000 ppm, and an aqueous solution of sodium benzoate with a concentration
 of 900 ppm were prepared, and these three types of aqueous solution were
 mixed in equal amounts to prepare a bactericide containing iron ions. Each
 of 20 test tubes was filled with 10 mL of this bactericide. Dry earth and
 sand containing numerous spores from the Bacillus and Clostridium genera
 were sampled from 20 sites, and 0.2 g of each was added to the bactericide
 in the above-mentioned test tubes. These were allowed to stand for 120
 minutes, after which the used bactericides were checked for bacteria, but
 no spores of either the Bacillus genus or the Clostridium genus were
 detected, let alone any ordinary bacteria, in 19 of the test tubes.
 However, the presence of 12 spores per mL of bactericide was detected in
 the remaining tube.
 The strength of an antiseptic or bactericide is generally highest
 immediately after its manufacture, and declines gradually as time passes.
 Nevertheless, as a result of the addition of L-ascorbic acid, the iron
 ion-containing bactericide of the present invention is at its most
 powerful several months after its manufacture, as shown in FIG. 1, with a
 stable bactericidal strength being maintained over an extended period.
 Also, as to color, the bactericide changes into a solution that appears
 colorless and transparent.
 Effect of the Invention
 The iron ion-containing bactericide of the present invention has as its
 components ferric ions, which are structural elements of the body, and
 compounds approved for use as food additives, and is therefore highly
 stable and can be used in a wide range of applications, from the
 sterilization of hands and wounds, to the sterilization of furniture,
 tools, and objects, to the sterilization of fresh foods prior to cooking.
 Also, the major pathogenic bacteria, such as MRSA or E. coli O-157 can be
 killed in about 10 seconds of contact with the bactericide, and even over
 90% of spores can be killed at a contact time of 120 minutes. Furthermore,
 this bactericide has many advantages not found in conventional
 antiseptics, such as an effect that is stable over extended periods, and
 is more convenient to use.