粘质沙雷氏菌调节突变体生产苏氨酸的研究
Threonine production by regulatory mutants of Serratia marcescens.
作者信息
Komatsubara S, Kisumi M, Murata K, Chibata I
出版信息
Appl Environ Microbiol. 1978 May;35(5):834-40. doi: 10.1128/aem.35.5.834-840.1978.
beta-Hydroxynorvaline (alpha-amino-beta-hydroxyvaleric acid)-resistant mutants of Serratia marcescens deficient in both threonine dehydrogenase and threonine deaminase were isolated and characterized. One of the mutants, strain HNr21, lacked feedback inhibition of threonine-sensitive aspartokinase and homoserine dehydrogenase, was repressed for the two enzymes, and produced 11 mg of threonine per ml of medium containing a limiting amount of isoleucine. The other mutant, strain HNr59, was constitutively derepressed for aspartokinase and homoserine dehydrogenase. Its kinase was sensitive to feedback inhibition, but its dehydrogenase was insensitive to feedback inhibition. This strain produced 5 mg of threonine per ml of medium containing either a limiting or an excess amount of isoleucine. Diaminopimelate auxotrophs derived from strain HNr59 produced more threonine (13 mg/ml) than the parent strain. However, similar auxotrophs derived from strain HNr21 produced the same amount of threonine as that produced by the parent strain.
分离并鉴定了粘质沙雷氏菌中对β-羟基正缬氨酸（α-氨基-β-羟基戊酸）具有抗性的突变体，这些突变体同时缺乏苏氨酸脱氢酶和苏氨酸脱氨酶。其中一个突变体HNr21菌株，缺乏对苏氨酸敏感的天冬氨酸激酶和高丝氨酸脱氢酶的反馈抑制，这两种酶受到阻遏，并且在每毫升含有限量异亮氨酸的培养基中产生11毫克苏氨酸。另一个突变体HNr59菌株，天冬氨酸激酶和高丝氨酸脱氢酶组成型去阻遏。其激酶对反馈抑制敏感，但其脱氢酶对反馈抑制不敏感。该菌株在每毫升含有限量或过量异亮氨酸的培养基中产生5毫克苏氨酸。源自HNr59菌株的二氨基庚二酸营养缺陷型产生的苏氨酸（13毫克/毫升）比亲本菌株更多。然而，源自HNr21菌株的类似营养缺陷型产生的苏氨酸量与亲本菌株产生的量相同。
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