• Microbiology and Biotechnology Letters
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• v.22 no.6
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• pp.621-626
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• 1994

Cysteine showed strong inhibitory effect on growth and protease production of Pseudo- monas sp. RP-222 and its mutant, MR-3966. Mid- to late-log phase cells were most sensitive to the presence of 10 mM cysteine. The inhibition caused by cysteine was almost completely overcome by addition of isoleucine, leucine and valine mixture to the medium, and inclusion of iso#leucine alone could greatly reduce the inhibitory effects of cysteine. Homocysteine and #cysteine, sulfur compounds having similar structure as cysteine, inhibited to varying degrees the growth of both strains. Cysteine and homocysteine were strong inhibitors of threonine deaminase but not transa#- minase B. These results suggest a relationship between the growth-inhibitory effects of cysteine and other sulfur compounds and the inhibition of isoleucine synthesis at the level of threonine deaminase.

• Microbiology and Biotechnology Letters
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• v.19 no.4
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• pp.383-389
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• 1991

In order to produce alkaline protease, psychrotrophic bacterium which have high enzyme activity at low temperature, was isolated by using enrichment culture from various samples and identified as genus alkalopsychrotropic Pseudomonas sp. RP-222. The optimal culture conditions for enzyme production were pH- 10.0, temperature-$20^{\circ}C$ and culture time-4 days. The optimum pH and temperature for the enzyme activity were pH 10.5 and $40^{\circ}C$, respectively and the enzyme was relatively stable at pH 7.0~13.0 and below $50^{\circ}C$. The enzyme was inhibited by ethylenediaminetetraacetate and phenylmethylsulfonylfluoride, indicating that the enzyme was a serine metalloenzyme, but considerably stable in the presence of surface active agents. Activity of the enzyme was increased by the addition of 0.05% Na-$\alpha$-olefin sulfonate.