微生物谷氨酰胺转胺酶高产菌株的诱变选育

以本实验室筛选的Streptomyces sp.WZFF.W—12(谷氨酞胺转胺酶活0．24U／ml)为出发菌株，孢子经预培养处理处于萌发状态后制备成单孢子悬浮液，用1—甲基—3—硝基—1—亚硝基服(NTG)单独和结合羟胺进行多次复合诱变处理。实验发现，诱变处理后菌落的形态变异等特征与产酶能力呈相关关系，并被用于最初的突变菌落挑选。接着先后采用蛋白质交联凝絮—沉淀性能分析的初筛试验和摇瓶测定酶活的复筛试验分离选育高产酶突变菌株，最后获得一产酶活力达2．18U／ml的高产菌株W—12var HZ3，酶活相对提高了8倍。对该菌株进行分类鉴定方面的理化性能测试和传代实验结果表明，该菌遗传性较为稳定，而且其理化性能与已报道的产酶菌种明显不同。

Mutation Breeding of Potent Microbial Transglutaminase-producing Streptomyces Strains

The spores of Streptomyces sp.WZFF.W-12 isolated from soil in our laboratory to produce microbial transglutaminase(MTG) about 0.24U/ml,were precultured and then treated several times by NTG singly and with hydroxylammonium chloridefor complex genetic mutation. The results showed that some mutants were greatly different from the original strain in morphol-ogy of colony, and that these mutation phenomena were related to the MTG productivity and thereafter used for strainselection. first. Then, test of flocculation-precipitation of proteins through MTG cross-linking as the primary screening andexamination test of MTG production as the secondary screening were successively used to select potent strains. An effectivestrain named Streptomyces sp. WZFF.W-12.var HZ-3 was finally obtained from many regenerative mutants. The MTG activityof this new mutant reached 2.18U/ml,which has been increased about 8 times higher than that of the initial strain. Its geneticquality was proved to be stable by experiments, and its physiological and biochemical characteristics were obviously differentfrom the present strains reported producing MTG.