• Journal of Microbiology and Biotechnology
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• v.2 no.1
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• pp.14-20
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• 1992

Some microorganisms isolated from soil, including some bacteria and fungi, were found to secrete an extracellular soymilk-clotting enzyme. Among them, an isolated fungus showed the highest soymilk-clotting activity and the strain was assigned to genus Penicillium based on its cultural and morphological characteristics, and designated as Penicillium sp. L-151K. Soymilk-clotting enzymes A and B produced by Penicillium sp. L-151K were purified by ammonium sulfate precipitation and chromatographies on Sephadex G-25, CM-Sephadex, Sephadex G-100 and phenyl-Toyopearl gel. The two purified enzymes A and B were found to be homogeneous by polyacrylamide gel electrophoresis at pH 9.5. The molecular weights of enzyme A and B were 24, 000 and 40, 000, respectively, by gel filtration on Sephadex G-100. Enzymes A and B coagulated soymilk optimally at $60^\circ{C}$ and were stable up to $50^\circ{C}$. Both enzymes were most active at pH 5.8 for soymilk coagulation, and were stable with approximately 80% of original activity from pH 3.0 to 5.0. Each enzyme was an acidic protease with an optimum pH of 3.0 for casein digestion. The soymilk-clotting efficiency of these enzymes was improved with $CaCl_2\;or\;MgCl_2$ when making soymilk-curd.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.3
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• pp.273-279
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• 1993

Hydrolytic patterns of 11S globulin (glycinin), storage protein of soybean, by soymilk-clotting enzymes Iand IIfrom Bacillus sp. K-295G-7, which was the first soymilk-clotting enzyme to be found in a bacteria, was investigated. The clotting time of about 4~5 min is revealed by the Enzymes Iand II(0.025 units at 35$^{\circ}C$) on the acidic subunit. In electrophoresis, acidic subunit (A$_3$, M.W. 45,000) disappeared almost completely within 2 min and new products corresponding to the molecular weight of 16,000 and 20,000 were formed by the action of Enzymes I and II. Furthermore, Enzyme II produced a degradation compound having a molecular weight of about 30,000. In contrast, the hydrolytic patterns of basic subunit (M.W. 20,000) by Enzymes I and II were similar, but Enzyme II produced low molecular weight products slower than that of Enzyme I.

• Applied Biological Chemistry
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• v.33 no.2
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• pp.154-160
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• 1990

A bacterial strain which was capable of producing extracellular soymilk-clotting enzyme was isolated from soil samples during the course of screening test. The characteristics of the isolated strain K-324-7, indicated that the strain belonged to species of Bacillus cereus. The crude purification of this enzyme was precipitated by salting out with ammonium sulfate of 0.8 saturation. The optimal pH for the enzyme activity was at $6.1{\sim}7.0$ and below $50^{\circ}C$. The optimal culture medium for the production of soymilk-clotting enzyme were consisted of 0.2% glucose, 0.2% peptone, and 0.5% $KH_2PO_4$ with initial pH value of 6.5. The activity of enzyme was maximum when the microbe was cultured for 3 days at $35^{\circ}C$.

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.109-115
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• 1991

Twenty-five fungal strains producing an extracellular soybean milk clotting enzyme were isolated from 146 soil samples, and identified as 11 species belonging to six genera of Aspergillus oryzae (5 strains), Aspergillus flavus (2 strains), Aspergillus parasiticus (1 strain), Aspergillus tamarii (2 strains), Aspergillus niger (4 strains), Aspergillus fumigatus (2 strains), Mucor hiemalis (2 strains), Wallemia sebi (4 strains), Scopulariopsis condida (1 strain), Fusarium redolens(1 strain) and Verticillum lecanii (1 strain). Among them, Aspergillus oryzae 020 and Aspergillus tamarii 287 showed relatively high soybean milk clotting activity. The coagulabilities of the enzyme from representative strains of those species decreased as the pH of soybean milk increased from 6.0 to 7.0 The optimum temperature for soybean milk clotting enzymes of those strains were 65$^{\circ}C$.

• Microbiology and Biotechnology Letters
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• v.17 no.2
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• pp.109-114
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• 1989

Seventeen bacterial strains producing an extracellular soybean milk clotting enzyme were Isolated from 150 soil samples, and identified as Bacillus cereus(8 strains), Bacillus pumilus(8 strains) and Bacillus licheniformis (1 strain). Among them, Bacillus pumilus strain 118 and Bacillus licheniformis strain 192 showed relatively high soybean milk clotting activity. The coagulability of enzymes from these strains decreased as the pH of soybean milk was increased from 6.0 to 7.0. The optimum temperature for soybean milk clotting activity was $65^{\circ}C$.