光学纯度L(+)-乳酸高产菌株的选育

Screening of a optical purity L(+)-lactic acid high-production mutant strain

从60份不同来源的土壤样品中筛选得到米根霉(Rhizopusoryzae)为出发菌株,通过紫外线和60Coγ射线诱变处理,运用推理育种技术,选育到一株有较高的乳酸脱氢酶活性和耐高渗的L(+)-乳酸高产突变株Rhi3-2.该菌株产L(+)-乳酸光学纯度高,最高产量为88.45g/L,较出发菌株提高91.24%,糖利用率提高17.87%,耗糖酸产率提高35.15%.菌株经8次传代培养,L(+)-乳酸产量下降10.7%,是一株性状较稳定可深入研究开发的优良菌株.

Parent strain Rhizopus oryzae producing L(+)-lactic acid was isolated from 60 soil samples. A high-production mutant Rh3-2 was obtained from its parent strain Rhizopus oryzae by UV and ()(60)Coγ-ray treatment and rational screening. Mutant Rh3-2 is resistant to catabolic repression by high-concentration glucose and it produced higher optical purity L(+)-lactic acid. The L(+)-lactic acid prodution reached 88.45 g/L by flask culture, which was 91.24% higher than the parent strain. A desecend of only 10.7% in the L(+)-lactic acid yield of the mutant was observed after eight times of subculture. Therefore, the obtained mutant is a stable strain that is worthwhile to be studied further.