一株耐高温L-乳酸高产菌的选育及其发酵特征

Breeding and Characterization of a Thermotolerant and High-yield Lactobacillus rhamnosus for L-Lactic acid Production

对鼠李糖乳杆菌菌株Lactobacillus rhamnosusJCM1553进行紫外诱变,选育得到一株耐高温L-乳酸高产突变菌GX-6。在47℃,分别以葡萄糖和木薯淀粉为底物,研究GX-6菌株发酵生产L-乳酸的情况并考察GX-6菌株的遗传稳定性。结果表明,以葡萄糖为底物时,发酵56h的L-乳酸产量达到117g/L,比出发菌(100g/L)提高17%,糖酸转化率68.8%;以木薯淀粉为底物时,发酵72h的L-乳酸产量达到138g/L,比出发菌株(73g/L)提高77.6%,糖酸转化率达到85.4%。经16次传代培养,GX-6菌株的乳酸发酵性能没有发生显著变化,具有较好的遗传稳定性。

By UV mutagenesis,a high-yield and thermostable L-lactic acid mutant strain-GX-6 was originally obtained from Lactobacillus rhamnosus JCM1553.At 47℃,the maximum L-lactic acid yield of GX-6 in glucose was 117g/L for 56h,which was 17% higher than that of the original strain（100g/L）,with a conversation rate of 68.8 %.The maximum L-lactic acid yield was 138g/L for 72h under the same condition in cassava starch,77.6% higher than that of the original strain（73g/L） and the conversation rate reached to 85.4%.After subculture for 16 generations,the L-lactic acid production capacity of GX-6 remains unchanged,indicating that the mutant is stable.