Novel microorganisms and a process for preparing 3alpha, 7alpha-dihydroxy-12-keto-5beta-cholanic acid

Abstract: The present invention provides microorganisms of the genus Bacillus capable of predominantly producing 3α,7α-dihydroxy-12-keto-5β-cholanic acid from 3α,7α,12α-trihydroxy-5β-cholanic acid and mutant strains thereof and use of such microorganisms in preparing 3α,7α-dihydroxy-12-keto-5β-cholanic acid.

Description: The present invention relates to novel microorganisms and a process for preparing 3α,7α-dihydroxy-12-keto-5β-cholanic acid (referred hereinafter as 12-keto-cholic acid), which is an intermediate in the preparation of chenodeoxycholic acid, useful as a gallstone dissolving agent and a raw material for the preparation of ursodeoxycholic acid, itself a cholanopoietic agent, from 3α,7α,12α-trihydroxy-5β-cholanic acid (referred hereinafter as cholic acid) by the use of microorganisms. A chemical process for preparing 12-keto-cholic acid from cholic acid by selective oxidation of the hydroxyl group at the 12-position of cholic acid is known. Micro-biological processes for preparing 12-keto-cholic acid from cholic acid are also known, such as, for example, by the use of Micrococcus (Japanese Patent Publication No. 1-51998), and by the use of Arthrobacter (Japanese Patent Publication Hei 1-20873, Japanese Patent Publication No. Hei 2-62234). However, the prior art chemical process for preparing 12-keto-cholic acid has problems concerning reactivity, selectivity of the reaction and safety in operation, and is unsatisfactory with regard to the yield and the purity of the resulting products. The latter process using microorganisms is also not necessarily satisfactory because the microorganisms essentially assimilate the cholic acid substrate and produce some by-products, and the process is also unsatisfactory with regard to the yield and the purity of the products. As the results of our researches into microorganisms capable of producing 12-keto-cholic acid, and processes for preparing 12-keto-cholic acid by the use of said microorganisms, we have found that a microorganism belonging to a genus of Bacillus which is capable of growth in a high alkaline culture medium containing a high concentration of cholic acid wherein usual microorganisms do not grow produces 12-keto-cholic acid, 3α,12α-dihydroxy-7-keto-5β-cholanic acid and 3α-hydroxy-7,12-diketo-5β-cholanic acid as the main converting products from cholic acid substrate, and we named the microorganism Bacillus sp. TTUR 2-2 (deposited at the Fermentation Research Institute, Agency of Industrial Science and Technology (Japan) under deposit No. FERM P-11861 (referred hereinafter as FERM11861) on 22 November 1990). This microorganism was isolated from the soil of Yonezawa city Yamagata prefecture. This bacterium has the ability to oxidize hydroxy groups, mainly at the 7-position and 12-position of cholic acid to keto groups, and to a lesser extent, the 3-position of cholic acid to keto group, but has no ability to assimilate or decompose cholic acid. Further as said bacterium can grow in a highly alkaline medium, it is possible to prepare culture media containing a high concentration of cholic acid, and sterilization of the culture media prior to cultivation of bacteria, which is normally necessary for conventional culture media is not required. We have attained the present invention through isolation of mutant strains having productivity of 12-keto-cholic acid from cholic acid with substantially 100% conversion and substantially 100% yield by means of mutagenic treatment such as irradiation with ultraviolet rays, X-rays, gamma-rays and so forth, or by contact with a mutagenic agent such as N-methyl-N'-nitro-N-nitrosoguanidine (referred herein after as NTG), 4-nitroquinoline-N-oxide, acriflavin, ethyl methane sulfonate and so forth. Therefore the present invention relates to a process for preparing 12-keto-cholic acid comprising cultivating a bacterium belonging to the genus Bacillus having 12-keto-cholic acid producing capability in a nutrient medium containing cholic acid, allowing the bacterium to produce 12-keto-cholic acid in the culture medium and optionally collecting the 12-keto-cholic acid. According to one aspect, the present invention provides a microorganism of the genus Bacillus capable of predominantly producing 3α,7α-dihydroxy-12-keto-5β-cholanic acid from 3α,7α,12α-trihydroxy-5β-cholanic acid (cholic acid) and mutant strains thereof having said activity of oxidizing the 12α hydroxy group of cholic acid to predominantly produce 3a,7a-dihydroxy-12-keto-5β-cholanic acid. According to another aspect the present invention provides a process for preparing 3α,7α-dihydroxy-12-keto-5β-cholanic acid comprising cultivating a microorganism capable of producing 3α,7α-dihydroxy-12-keto-5β-cholanic acid belonging to the genus of Bacillus in a nutrient medium containing 3α,7α,12α-trihydroxy-5β-cholanic acid, letting the microorganism produce 3α,7α-dihydroxy-12-keto-5β-cholanic acid in the culture medium and optionally collecting said acid. Examples of microorganisms of the present invention originating from Bacillus sp. TTUR 2-2 are Bacillus sp. TTUR 2-M4-124 (deposited at the Fermentation Research Institute, Agency of Industrial Science and Technology under Accession No. FERM BP-3394 on 13 May 1991) and Bacillus sp. TTUR 2-M4-336 (deposited at the Fermentation Research Institute, Agency of Industrial Science and Technology under Accession No. FERM BP-3397 on 13 May 1991). Methods for isolating said bacteria are as follows: (1) Bacillus sp. TTUR 2-M4-124 A platinum loopful of Bacillus sp. TTUR 2-2 cultivated on a slant of alkaline NA medium (composition: normal broth 'EIKEN' (trade name) 1.8%, agar 1.8%, sodium carbonate 0.75%, pH10) was inoculated into a test tube (30⊘x190mm) containing 20ml of HORIKOSHI medium I (composition: glucose 1%, peptone 0.5%, yeast extract 0.5%, dipotassium hydrogen phosphate 0.1%, magnesium sulfate 7hydrate 0.02%, sodium carbonate 1%, pH10), and cultured with shaking at 30°C for 16 hours. Then, the above cells in logarithmic growth phase were collected aseptically by means of centrifugal separation, and washed with 10ml of 0.1M tris-maleic acid buffer (pH8.0) three times. The cells after washing were added to 25ml of the same buffer solution to form a suspension, then NTG was added to the suspension so that the final concentration of the NTG should be 60 µg/ml, and the cell suspension was incubated at 30°C for 30 minutes and subjected to mutagenic treatment. The death rate of the Bacillus sp. TTUR 2-2 during said treatment was 85%. Then 1ml of the bacterial suspension was diluted with 9ml of 0.1M sodium carbonate buffer (pH9.5), and the cells collected by means of a centrifugal separator; after washing twice with the same buffer, the cells were suspended in 10ml of alkaline NB medium (composition: normal broth 'EIKEN' 1.8%, sodium carbonate 0.75%, pH10). The bacterial suspension thus prepared was optionally diluted with alkaline NB medium, applied on the alkaline NA plating culture medium so that 10-100 colonies should appear, and cultured at 30°C for two days. Among the colonies which appeared, a colony of medium size after two days growth from the start of the cultivation was isolated and transplanted to a slant of 5% CA agar medium (composition: a medium adding cholic acid 5%, sodium hydroxide 0.5%, agar 1.8% to the HORIKOSHI medium I, pH10), and the bacteria of the colony were cultured for three days at a temperature of 30°C. A well grown strain was selected and a platinum loopful of said strain was inoculated into a test tube (16.5⊘x165mm) containing 5% of CA liquid medium (composition: removing agar from 5% CA agar pH10). The amount of medium in the test tube was 4ml. The strain in the test tube was cultured with shaking at 30°C for three days. Products converted in the culture medium were investigated by means of thin layer chromatography. We thereby have found a mutant strain specifically producing 3α-hydroxy-7,12-diketo-5β-cholanic acid; this strain was named Bacillus sp. TTUR 2-M4 (and was deposited at the Fermentation Research Institute, Agency of Industrial Science and Technology under Deposit No. FERM BP-3393 on 13 May 1991). This process for obtaining such a mutant strain is referred hereinafter as NTG treatment. Then the NTG treatment was repeated on the Bacillus sp. TTUR 2-M4 obtained by the above NTG treatment as a parent strain, except that 5% CA liquid medium was used as the medium for the initial culture, and NTG concentration in the NTG treatment was 60 µg/ml. As a result, we found a strain specifically producing 12-keto-cholic acid and we named the strain as Bacillus sp. TTUR 2-M4-124. The death rate of Bacillus sp. TTUR 2-M4 during above operation was 15%. (2) Bacillus sp. TTUR 2-M4-336 The NTG treatment was repeated on the Bacillus sp. TTUR 2-M4 obtained by above NTG treatment of (1) as a parent strain except that 5% CA liquid medium was used for the medium for the initial culture, and NTG concentration in the NTG treatment was 100 µg/ml. As a result, we found a strain specifically producing 12-keto-cholic acid and we named the strain as Bacillus sp. TTUR 2-M4-336. The death rate of Bacillus sp. TTUR 2-M4 during above operation was 45%. Bacteriological properties of said bacteria are listed in following tables 1 to 4. Methods for tests and classifications are according to the BERGEY's MANUAL OF Systematic Bacteriology, and unless otherwise defined, to all media used herein sodium carbonate was added to adjust the pH to pH10. Morphology of various Bacillus sp. TTUR Bacillus sp. TTUR TTUR 2-2 TTUR 2-M4 TTUR 2-M4-124 TTUR 2-M4-336 form rod rod rod rod size (µm) 0.4-0.7 x 1.5-4.5 0.4-0.7 x 1.5-4.5 0.4-0.7 x 1.5-4.5 0.4-0.7 x 1.5-4.5 polymorphism none(partially chained) none(partially chained) none(partially chained) none(partially chained) flagellum peritrichous peritrichous peritrichous peritrichous spore site near cell end near cell end near cell end near cell end sporangium swells slightly swells slightly swells slightly swells slightly size (µm) 0.3-0.7 x 0.6-1.2 0.3-0.7 x 0.6-1.2 0.3-0.7 x 0.6-1.2 0.3-0.7 x 0.6-1.2 gram-stain variable variable variable variable acid fastness none none none none Growth of bacteria in various media (TTUR 2-2, TTUR 2-M4, TTUR 2-M4-124 and TTUR 2-M4-336 show folowing growth conditions.) growth condition type of medium pH7.0 pH10.0 nutrient agar plate culture poor irregular, convex, auriculate or lobate; milky white and lustrous nutrient agar slant culture poor grows in a spreading state cloth. no pigment formed nutrient liquid culture slightly grows grows, slightly turbid sediment observed gelatin stab culture not liquefied due to insufficient growth liquefied in stratiform litmus milk change hardly observed grows and liquefying no litmus color change due to alkalinity Physiological properties of TTUR 2-2, TTUR 2-M4, TTUR 2-M4-124 and TTUR 2-M4-336 reduction of nitrate salts none or very weak denitrification reaction unobserved MR (methyl red) test no change observed due to alkalinity of the medium VP test negative indol formation none hydrogen sulfide formation none hydrolysis of starch reactive utilization of citric acid Kozer's medium not utilized Christensen's medium utilized inorganic nitrogen ammonium salts scarcely utilized nitrate salts scarcely utilized pigment formation none urease(pH9) negative oxidase positive catalase positive growth range : pH pH7-11(optimum pH9-10) :temp.(of 2-M4-124, 336) 15-40° C(optimum 30- 37° C) (of TTUR 2-2, 2-M4) 15-43° C(optimum 30-37° C) attitude to oxygen aerobic O-F test grows in aerobic condition, slightly forms acid, but not gas sodium chloride resistance grows in 10% sodium chloride, but not in 15% sodium chloride Acid and gas formation from various sugars (pH9) sugar production TTUR 2-2 TTUR 2-M4 TTUR 2-M4-124 TTUR 2-M4-336 L- acid ± ± ± - arabinose gas - - - - D-xylose acid ± - ± - gas - - - - D-glucose acid ± ± ± ± gas - - - - D-mannose acid - - - - gas - - - - D-fructose acid + + + + gas - - - - D- galactose acid - - - - gas - - - - maltose acid + + + + gas - - - - sucrose acid + + ± - gas - - - - lactose acid - - - - gas - - - - trehalose acid + + ± + gas - - - - D-sorbit acid - - - - gas - - - - D-mannit acid + + + + gas - - - - D-inosit acid - - - - gas - - - - glycerol acid - - - - gas - - - - starch acid + + + + gas - - - - According to the above observations, it is apparent that Bacillus sp. TTUR 2-2 is a microorganism belonging to the genus of Bacillus because Bacillus sp. TTUR 2-2 is a sporeforming and aerobic bacterium. However, since the optimum pH for growth is on the alkaline side, in the pH range of 9 to 10, Bacillus sp. TTUR 2-2 is not a typical Bacillus microorganism. And when comparing Bacillus sp. TTUR 2-2 with Bacillus alcalophilus and Bacillus alcalophilus subsp. halodurans known as standard alkalophilic bacteria in Bacillus , there are remarkable differences between them in the form and the periphery of the colony. As alkalophilic strains having irregular shape of colony and lobate colony periphery, Bacillus cereus 8-1 (FERM 2885, Japanese Patent Publication NO. Sho 53-13708) and Bacillus alcalophylus 202-1 (FERM 2674, Japanese Patent Publication No. Sho 53-27786) have been reported, but their colony forms are different from that of Bacillus sp. TTUR 2-2. In table 5, Main characteristics of Bacillus sp. TTUR 2-2, Bacillus sp. TTUR 2-M4-124, Bacillus sp. TTUR 2-M4-336 and Bacillus alcalophilus are shown, and in table 6, main characteristics of Bacillus alcalophilus subsp. halodurans, Bacillus cereus 8-1 (FERM2885, Japanese Patent Publication No. Sho 53-13708) and Bacillus alcalophilus 202-1, (FERM 2674, Japanese Patent Publication No. Sho 53-27786), respectively, are shown. Main characteristics of bacteria(No.1) Bacillus sp. TTUR 2-2 TTUR 2-M4-124 TTUR 2-M4-336 Bacillus alcalophilus colony shape irregular irregular irregular circular colony periphery auriculate auriculate auriculate entire colony color milky white milky white milky white milky white gelatin liquefactor stratiform stratiform stratiform stratiform growth under anaerobic environment - - - - growth temp. 15-43° C 15-40° C 15-40° C up to 46° C optimum temp. 30-37° C 30-37° C 30-37° C 33-35° C NaCl tolerance (15%) - - - - utilization of ammonium salt - - - reduction of nitrate - - - - utilization of citric acid(Kozer's) - - - - acid formation from sugar ± ± - + L-alabinose ± ± - + D-xylose ± ± ± + D-glucose sucrose + ± - + Main characteristics of bacteria (No.2) Bacillus Bacillus alcalophilus subsp. halodurans Bacillus cereus 8-1(FERM 2885) Bacillus alcalophilus 202-1 (FERM 2674) colony shape circular irregular irregular colony periphery entire lobate lobate colony color milky white light yellow milky white gelatin liquefactor crateriform stratiform growth under anaerobic environment + - + growth temp. below 54° C below 45° C below 50° C optimum growth temp. about 48° C 40-45° C 40-43° C NaCl tolerance (15%) + utilization of ammonium salt - ± reduction of nitrate + utilization of citric acid (Kozer's) ± + acid formation from sugar L-alabinose + + + D-xylose + + + D-glucose + + + sucrose + + + It is reasonable to classify TTUR 2-2 as a new species of bacterium because TTUR 2-2 is distinguishable from known species with respect to bacteriological properties, especially optimum pH range for growth, which is towards the alkaline side, at a pH of around 9 to 10, even though TTUR 2-2 is a sporeforming aerobic bacterium. Since it is generally thought that mutant strains usually belong to the same species as their parent strain, we concluded that the Bacillus TTUR 2-M4-124 and TTUR 2-M4-336, being secondary mutants of Bacillus sp. 2-2, belong to the same species of bacteria as the parent strain. Namely, bacteria of the present invention are not limited to Bacillus sp. TTUR 2-M4-124 and TTUR 2-M4-336, but include any bacteria which belong to the genus Bacillus and are able to produce 12-keto-cholic acid from cholic acid substrate. The culture media used in the present invention may be any media in which the bacteria of the invention can grow, for example, as carbon sources, saccharides such as glucose, fructose, maltose, saccharose, glycerine, starch, bran, black molasses waste, and the like, and as nitrogen sources, organic nitrogen compounds such as peptone, meat extract, yeast extract, corn steep liquor, soybean meal, rapeseed oil cake, various amino acids, amino sugars, and the like, and inorganic nitrogen compounds such as ammonium nitrate, ammonium chloride, sodium nitrate and the like, can be used. And further it is preferable to add a trace amount of inorganic metal salts, vitamins, growth promoting factors, and the like. The concentration of cholic acid in the culture medium, though not specifically limited, may having regard to the yield of 12-keto-cholic acid and cultivation conditions, conveniently be in the range of 1 to 500g/l, preferably 40 to 300 g/l. Cultivation of the present invention may be performed in aerobic atmosphere, under, for example, ventilated agitation or reciprocal shaking. Cultivation conditions are usually set at a temperature of 20 to 40°C, pH 7 to 11, for 1 to 6 days. The desired product 12-keto-cholic acid may be isolated from the culture medium as follows: firstly, bacteria and unnecessary components in the culture media are removed by means of filtration, centrifugal separation, etc., and the resulting filtrate or supernatant liquid is acidified by addition of hydrochloric acid or sulfuric acid. By this operation, 12-keto-cholic acid precipitates in high yield. Then the precipitate is filtered, and after recrystallization, high purity 12-keto-cholic acid is obtained. 12-keto-cholic acid obtained according to the present invention may be easily converted by Wolff-Kishner reduction into chenodeoxycholic acid useful as a gallstone solubilizing agent. The present invention will be further explained with reference to the following examples, but it is understood that the examples are not meant to restrict the range of the present invention. In each example, the identification of the products is carried out by means of thin layer chromatography or high performance liquid chromatography under the conditions as follows: (1) Thin layer chromatography Carrier: Kieselgel 60 (0.25mm thickness, Merk), Development Solution: benzene/isopropanol/acetic acid (40/10/1 volume ratio) Color change test: spraying phosphomolybdic acid - sulfuric acid reagent (dissolving 1g of phosphomolybdic acid in 20ml of methanol, and adding thereto 1ml of concentrated sulfuric acid ), and heating till a bile acid spot turns to deep blue. (2) High performance liquid chromatography Column : INERTOSIL ODS column (column size 4.6⊘x250mm, GL science ) Mobile phase : methanol/refined water/phosphoric acid (70/30/0.02M weight ratio) Flow rate : 1.0ml/min. Detector : RI Example 1 Bacillus sp. TTUR 2-M4-124 (FERM 3394) was cultivated according to the method as follows: 10g of glucose, 5g of peptone, 5g of yeast extract, 1g of dipotassium hydrogen phosphate and 0.2g of magnesiumsulfate-7hydrates were dissolved in 500ml of refined water, and separately 50g of cholic acid, 5g of sodium hydroxide and 10g of sodium carbonate were dissolved in 500g of refined water, and the two solutions were sterilized at the temperature of 121° C for 15 minutes. After cooling, the two solutions were mixed, and the mixture was used for a culture medium (pH10). Bacillus sp. TTUR 2-M4-124 (FERM 3394) was cultivated under shaking at the temperature of 30° C for 20 hours in a test tube containing 20ml of the culture medium of above composition except cholic acid and sodium hydroxide were excluded, in this manner a bacterium solution was prepared. 20ml of above culture medium was placed into a test tube(30⊘x190mm), and 0.1ml of said bacterium solution was aseptically inoculated therein, and the bacterium was cultivated under shaking at 30° C for 3 days. After this cultivation, the bacterium was removed by centrifugation, 12-keto-cholic acid and unconverted cholic acid were precipitated by adding diluted sulfuric acid to the supernatant liquid formed by said separating procedure and making said supernatant liquid acid. Then precipitate formed was collected, and after drying 0.999g of white powder was obtained. A part of said powder was taken, and the ratio of cholic acid and 12-keto-cholic acid in the product was analyzed by means of high performance liquid chromatography, and the results were cholic acid 1.7%, 12-keto-cholic acid 98.3% (recovery rate: 99.9%). Pure 12-keto-cholic acid was obtained by recrystallization of the mixture in methanol solution. Example 2 The procedure of Example 1 was proceeded except that the bacterium was replaced by Bacillus sp. TTUR 2-M4-336 (FERM 3397), the ratio in the product was cholic acid 1.8%, 12-keto-cholic acid 98.2% (recovery rate: 99.9%). Example 3 The procedure of Example 1 was proceeded except that glucose was excluded from the culture medium (pH10), the production ratio was cholic acid 1.9%, 12-keto-cholic acid 98.1%. Example 4 The procedure of Example 2 was proceeded except that glucose was excluded from the culture medium (pH10), the ratio in the product was cholic acid 0%, 12-keto-cholic acid 100%. Example 5 10g of soybean protein (ESUSAN-MEAT; trade name; AJINOMOTO Inc.), 1g of dipotassium hydrogen phosphate and 0.2g of magnesium sulfate 7hydrates were dissolved in 500ml of refined water, and 50 g of cholic acid, 5g of sodium hydroxide and 2g of sodium carbonate were dissolved in 500ml of refined water, then both solutions were sterilized at the temperature of 121° C for 15 minutes. After cooling, two solutions were mixed and the mixture was used for a culture medium (pH10.2). Thereafter, the same procedure as Example 1 was proceeded and 12-keto-cholic acid was obtained. The ratio in the product was cholic acid 0.5% and 12-keto-cholic acid 99.5%. Example 6 The procedure of Example 5 was proceeded except that the bacterium was replaced by Bacillus sp. TTUR 2-M4-336. The ratio in the product was cholic acid 1.2%, 12-keto-cholic acid 98.8%. Example 7 The procedure of Example 5 was proceeded except that dipotassium hydrogen phosphate and magnesiumsulfate 7hydrates were excluded from the medium and the amount of sodium carbonate was changed to 3g (pH10.3). The ratio in the product was cholic acid 0%, 12-keto-cholic acid 100%. Example 8 The procedure of Example 7 was proceeded except that the bacterium was replaced by Bacillus sp. TTUR 2-M4-336. The ratio in the product was 0.7%, 12-keto-cholic acid 99.3%. Example 9 10g of soybean protein (ESUSAN MEAT), 1g of yeast extract, 1g of dipotassium hydrogen phosphate and 0.2g of magnesium sulfate 7hydrates were dissolved in 500ml of refined water, and 50 g of cholic acid, 5g of sodium hydroxide and 4g of sodium carbonate were dissolved in 500ml of refined water, then both solutions were sterilized at the temperature of 121° C for 15 minutes. After cooling, two solutions were mixed and the mixture was used for a culture medium (pH10.2). Then, the procedure of Example 5 was proceeded except that the bacterium was replaced by Bacillus sp. TTUR 2-M4-336. The ratio in the product was cholic acid 0.1% and 12-keto-cholic acid 99.9%. Example 10 The procedure of Example 9 was proceeded except that soybean protein (ESUSAN-MEAT) was excluded from the medium and, instead, 20g of corn steep liquor was added to the medium, and the amount of sodium carbonate was changed to 12g (pH9.8). The ratio in the product was cholic acid 0.1%, 12-keto-cholic acid 99.9%. Example 11 The procedure of Example 5 was proceeded except that soybean protein (ESUSAN-MEAT) was excluded from the culture medium, instead, 10g of soybean protein (AJIPRON E3; trade name: AJINOMOTO Inc.) was added, and the amount of sodium carbonate was changed to 2g (pH10.0), and cultivation time was shortened to two days. The ratio in the product was cholic acid 0.2%, 12-keto-cholic acid 99.8%. Example 12 The procedure of Example 11 was proceeded except that the bacterium was replaced by Bacillus sp. TTUR 2-M4-336 and cultivation time was extended to 3 days. The ratio in the product was cholic acid 0.4%, 12-keto-cholic acid 99.6%. Example 13 5g of yeast extract, 1g of dipotassium hydrogen phosphate and 0.2g of magnesiumsulfate 7hydrate were dissolved in 500ml of refined water, and 50 g of cholic acid, 5g of sodium hydroxide and 4g of sodium carbonate were dissolved in 500ml of refined water, then both solutions were sterilized at the temperature of 121° C for 15 minutes. After cooling, two solutions were mixed and the mixture was used for a culture medium (pH9.7). Thereafter, the same procedure as Example 1 was proceeded. The ratio in the product was cholic acid 0.4% and 12-keto-cholic acid 99.6%. Example 14 The procedure of Example 13 was proceeded except that the bacterium was replaced by Bacillus sp. TTUR 2-M4-336. The ratio in the product was cholic acid 0.1%, 12-keto-cholic acid 99.9%. Example 15 The procedure of Example 14 was proceeded except that yeast extract was excluded from the culture medium and instead 5g of soybean peptide (D-4; trade name: FUJISEIYU Inc.) was added to the medium (pH9.8). The ratio in the product was cholic acid 0.8%, 12-keto-cholic acid 99.2%. Example 16 The procedure of Example 13 was proceeded except that yeast extract was excluded from the culture medium, and instead, 5g of soybean peptide (D-2; trade name: FUJISEIYU Inc.) was added and the amount of sodium carbonate was changed to 2g (pH of the medium is 9.2). The ratio in the product was cholic acid 0.1%, 12-keto-cholic acid 99.9%. Example 17 10g of glucose, 5g of peptone, 5g of yeast extract, 1g of dipotassium hydrogen phosphoric acid and 0.2g of magnesiumsulfate 7hydrates were dissolved in 500ml of refined water. And 100g of cholic acid, 10g of sodium hydroxide and 10g of sodium carbonate were dissolved in 500g of refined water. Then both solutions were sterilized at the temperature of 121° C for 15 minutes. After cooling, the two solutions were mixed and the mixture was used for a culture medium (pH10). Bacillus sp. TTUR 2-M4-124 was cultivated under shaking at the temperature of 30° C for 24 hours in a test tube containing 20ml of the culture medium of the above composition, and a bacterium solution was prepared. 20ml of said culture medium was placed into a test tube (30⊘x190mm), and 0.2ml of said bacterium solution was aseptically inoculated therein, and the bacterium in the test tube was cultivated under shaking at 30° C for 4 days. The same procedure as Example 1 was proceeded thereafter and 12-keto-cholic acid was obtained. The ratio in the product was cholic acid 3.3% and 12-keto-cholic acid 96.7%. Example 18 The procedure of Example 17 was proceeded except that the bacterium was replaced by Bacillus sp. TTUR 2-M4-336. The ratio in the product was cholic acid 2.7%, 12-keto-cholic acid 97.3%. Example 19 10g of glucose, 5g of peptone, 5g of yeast extract, 1g of dipotassium hydrogen phosphate and 0.2g of magnesium sulfate 7hydrates were dissolved in 500ml of refined water, and 50g of cholic acid, 5g of sodium hydroxide and 10g of sodium carbonate were dissolved in 500g of refined water, then both solutions were sterilized at the temperature of 121° C for 15 minutes. After cooling, the two solutions were mixed and the mixture was used for a medium (pH10). Bacillus sp. TTUR 2-M4-124 was cultivated under shaking at the temperature of 30° C for 24 hours in a test tube containing 20ml of above culture medium, and bacterium solution was prepared. 20ml of above culture medium was placed into a test tube(30⊘x190mm), and 0.2ml of the bacterium solution was aseptically inoculated therein, and the bacterium in the test tube was cultivated under shaking at 30° C for 2 days. The same procedure as the example 1 was proceeded thereafter and obtained 12-keto-cholic acid. The production ratio was cholic acid 0.7% and 12-keto-cholic acid 99.3%. Example 20 The procedure of Example 19 was proceeded except that the bacterium was replaced by Bacillus sp. TTUR 2-M4-336. The production ratio was cholic acid 0.8%, 12-keto-cholic acid 99.2%. Example 21 10g of glucose, 5g of peptone, 5g of yeast extract, 1g of dipotassium hydrogen phosphate and 0.2g of magnesium sulfate 7hydrates were dissolved in 500ml of refined water. 150g of cholic acid, 15g of sodium hydroxide and 10g of sodium carbonate were dissolved in 500g of refined water. And the two solutions were sterilized at the temperature of 121° C for 15 minutes. After cooling, the solutions were mixed and the mixture was used for a culture medium (pH10). Bacillus sp. TTUR 2-M4-124 was cultivated under shaking at the temperature of 30° C for 24 hours in a test tube containing 20ml of above culture medium, thus bacterium solution was prepared. 20ml of above culture medium was placed into a test tube(30⊘x190mm), 0.2ml of said bacterium solution was aseptically inoculated therein, and the bacterium in the test tube was cultivated under shaking at 30° C for 6 days. Thereafter, the same procedure as Example 1 was proceeded and 12-keto-cholic acid was obtained. The production ratio was cholic acid 17.3% and 12-keto-cholic acid 82.7%. Example 22 The procedure of Example 21 was proceeded except that the bacterium was replaced by Bacillus sp. TTUR 2-M4-336. The ratio in the product was cholic acid 15.2%, 12-keto-cholic acid 84.8%. Example 23 20g of glucose, 10g of peptone, 10g of yeast extract, 2g of dipotassium hydrogen phosphate and 0.4g of magnesium sulfate 7hydrates were dissolved in 1000ml of refined water. 100g of cholic acid, 10g of sodium hydroxide and 20g of sodium carbonate were dissolved in 1000g of refined water. And the two solutions were sterilized at the temperature of 121° C for 15 minutes. After cooling, the solutions were mixed in a desktype jar fermenter apparatus (51 size), and the mixture was used for a culture medium (pH10). Bacillus sp. TTUR 2-M4-124 was cultivated under shaking at the temperature of 30° C for 24 hours in a test tube containing 20ml of the culture medium of above composition except cholic acid and sodium hydroxide were excluded, thus bacterium solution was prepared. 20ml of above culture medium was placed into a test tube(30x190mm), 40ml of said bacterium solution was aseptically inoculated therein, and the bacterium in the jar fermenter was cultivated under agitation (300rpm) at the aeration rate 21/min. at 30° C for three days. After above cultivation, the bacteria was removed by means of centrifugal separation, and by adding diluted sulfuric acid to the supernatant liquid formed by said centrifugation, the pH was controlled at 2.5, 12-keto-cholic acid and unconverted cholic acid were precipitated. The precipitate was filtered, washed with water, and crystal was obtained and, after drying at the temperature of 50° C, 99.2g of white powder was obtained. A part of said powder was taken for characterization, and the ratio of cholic acid and 12-keto-cholic acid in the product was analyzed by means of high performance liquid chromatography, and the results were cholic acid 1.1%, 12-keto-cholic acid 98.9% (recovery rate: 99.2%). Example 24 The procedure of Example 23 was proceeded except that the bacterium was replaced by Bacillus sp. TTUR 2-M4-336. The ratio in the product was cholic acid 0.4%, 12-keto-cholic acid 99.6%(recovery rate: 98.9%). Example 25 20g of soybean protein (ESUSAN MEAT) was dissolved in 1000ml of refined water, and 100g of cholic acid, 10g of sodium hydroxide and 6g of sodium carbonate were dissolved in 1000g of refined water, and the two solutions were sterilized at the temperature of 121° C for 15 minutes. After cooling, the solutions were mixed in a desktype jar fermenter apparatus (51 size), and the mixture was used for a culture medium (pH10.4). Bacillus sp. TTUR 2-M4-336 was cultivated under shaking at the temperature of 30° C for 24 hours in a test tube containing 20ml of the culture medium of above composition except cholic acid and sodium hydroxide were excluded, thus a bacterium solution was prepared. 20ml of above culture medium was placed into a test tube(30⊘x190mm), 40ml of said bacterium solution was aseptically inoculated therein, and the bacterium in the test tube was cultivated under agitation (300rpm) at the aeration rate 21/min. at 30° C for three days. A trace amount of antifoaming agent (EINOL; trade name; BIOTT Co. LTD) was added during this operation. And thereafter, the same procedure as Example 23 was proceeded and 12-keto-cholic acid was obtained. The ratio in the product was cholic acid 0.7%, 12-keto-cholic acid 99.3%(recovery rate: 99.2%). Example 26 20g of soybean protein (AJIPRON E3), 2g of dipotassium hydrogen phosphate and 0.4g of magnesium sulfate 7hydrates were dissolved in 1000ml of refined water, and 100 g of cholic acid, 10g of sodium hydroxide and 5g of sodium carbonate were dissolved in 1000ml of refined water, then both solutions were sterilized at the temperature of 121° C for 15 minutes. After cooling, the two solutions were mixed in a desktype jar fermenter apparatus(51 size), and the mixture was used for a culture medium (pH10.5). Thereafter, the procedure of Example 23 was proceeded except that the cultivation time was changed to two days. The ratio in the product was cholic acid 0.4% and 12-keto-cholic acid 99.6%(recovery rate: 99.8%). Example 27 The procedure of Example 26 was proceeded except that the bacterium was replaced by Bacillus sp. TTUR 2-M4-336, that cultivation time was changed to three days and that a trace amount of antifoaming agent (EINOL) was added during the cultivation. The ratio in the product was cholic acid 0.4%, 12-keto-cholic acid 99.6% (recovery rate: 99.2%). Example 28 10g of soybean protein (AJIPRON E3), 1g of yeast extract, 2g of dipotassium hydrogen phosphate and 0.4g of magnesium sulfate 7hydrates were dissolved in 1000ml of refined water, and 100 g of cholic acid, 10g of sodium hydroxide and 6g of sodium carbonate were dissolved in 1000ml of refined water, then both solutions were sterilized at the temperature of 121° C for 15 minutes. After cooling, two solutions were mixed in a desktype jar fermenter apparatus (51 size), and the mixture was used for a culture medium (pH10.7). Thereafter, the same procedure as Example 26 was proceeded. The ratio in the product was cholic acid 0.6% and 12-keto-cholic acid 99.4% (recovery rate 98.9%). Example 29 The procedure of Example 28 was proceeded except that the bacterium was replaced by Bacillus sp. TTUR 2-M4-336, that cultivation time was changed to three days and that a trace amount of antifoaming agent (EINOL) was added during the cultivation. The ratio in the product was cholic acid 0.6%, 12-keto-cholic acid 99.4% (recovery rate: 99.4%). Example 30 10g of soybean protein (AJIPRON E3), 1g of yeast extract, 2g of dipotassium hydrogen phosphate and 0.4g of magnesium sulfate 7hydrates were dissolved in 1000ml of refined water, and 100 g of cholic acid, 10g of sodium hydroxide and 5g of sodium carbonate were dissolved in 1000ml of refined water, and without sterilization, two solutions were mixed in a desktype jar fermenter apparatus(51 size), and the mixture was used for a culture medium (pH10.4). Bacillus sp. TTUR 2-M4-124 was cultivated under shaking at the temperature of 30° C for 20 hours in a test tube containing 20ml of above culture medium and thus a bacterium solution was prepared. 40ml of said bacterium solution was aseptically inoculated therein, and the bacterium in the jar fermenter was cultivated under agitation (300rpm) at the aeration rate 21/min. at 30° C for three days. And thereafter, the same procedure as Example 23 was proceeded. The ratio in the product was cholic acid 0%, 12-keto-cholic acid 100% (recovery rate: 99.1%). Example 31 The procedure of Example 30 was proceeded except that the bacterium was replaced by Bacillus sp. TTUR 2-M4-336. The ratio in the product was cholic acid 1.5%, 12-keto-cholic acid 98.5%(recovery: rate 98.8%).

Claims: A microorganism of the genus Bacillus capable of predominantly producing 3α,7α-dihydroxy-12-keto-5β-cholanic acid from 3α,7α,12α-trihydroxy-5β-cholanic acid (cholic acid) and mutant strains thereof having said activity of oxidising the 12α hydroxy group of cholic acid to predominantly produce 3α,7α-dihydroxy-12-keto-5β-cholanic acid. A microorganism as claimed in claim 1 being Bacillus sp. TTUR 2-M4-124 (deposited at the Fermentation Research Institute, Agency of Industrial Science and Technology under Accession No. FERM BP-3394) and mutant strains thereof having said activity of oxidising the 12α hydroxy group of cholic acid to predominantly produce 3α,7α-dihydroxy-12-keto-5β-cholanic acid. A microorganism as claimed in claim 1 being Bacillus sp. TTUR 2-M4-336 (deposited at the Fermentation Research Institute, Agency of Industrial Science and Technology under Accession No. FERM BP-3397) and mutant strains thereof having said activity of oxidising the 12α hydroxy group of cholic acid to predominantly produce 3α,7α-dihydroxy-12-keto-5β-cholanic acid. A process for preparing 3α,7α-dihydroxy-12-keto-5β-cholanic acid comprising culturing a microorganism of the genus Bacillus capable of producing 3α,7α-dihydroxy-12-keto-5β-cholanic acid in a culture medium containing 3α,7α,12α-trihydroxy-5β-cholanic acid to produce a corresponding 12-keto derivative. A process as claimed in claim 4 wherein the pH of the culture medium is pH7 to pH11. A microorganism of the genus Bacillus capable of specifically producing 3α hydroxy-7,12-diketo-5β-cholanic acid from 5α,7α,12α-trihydroxy-5β-cholanic acid. A microorganism as claimed in claim 6 being Bacillus sp. TTUR 2-M4 (deposited at the Fermentation Research Institute, Agency of Industrial Science and Technology under Accession No. FERM BP-3393). A process for preparing 3α-hydroxy-7,12-diketo-5β-cholanic acid comprising culturing a microorganism of the genus Bacillus capable of producing 3α-hydroxy-7,12-keto-5β cholanic acid in a culture medium containing 3α,7α,12α-trihydroxy-5β-cholanic acid to produce a corresponding 7,12-keto derivative. A process for preparing 3α,12α-dihydroxy-7-keto-5β-cholanic acid comprising culturing a microorganism of the genus Bacillus capable of producing 3α,12α-dihydroxy-7-keto-5β cholanic acid in a culture medium containing 3α,7α,12α-trihydroxy-5β-cholanic acid to produce the corresponding 7-keto derivative.

Inventors: KAWAIDE HIROSHI, KIMURA HIROMI B, OKAMURA AKIO, KAWAIDE, HIROSHI, KIMURA, HIROMI, OKAMURA, AKIO, KIMURA, HIROMI, B-403, SYARUMU-KITAKOSHIGAYA
Applicants: TOKYO TANABE CO, TOKYO TANABE COMPANY LIMITED
Application year: 1992
Main classification: C12N1
IPC codes: C12P33, C12N1, C12R1