Laboratory of Microbial Technology, Division of Applied Molecular Microbiology and Biomass Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 6-10-1 Hakozaki, Higashi-ku Fukuoka 812-8581, Japan.
Appl Microbiol Biotechnol. 2011 Feb;89(4):1039-49. doi: 10.1007/s00253-010-2986-4.
Effective utilisation of cellulosic biomasses for economical lactic acid production requires a microorganism with potential ability to utilise efficiently its major components, glucose and cellobiose. Amongst 631 strains isolated from different environmental samples, strain QU 25 produced high yields of l-(+)-lactic acid of high optical purity from cellobiose. The QU 25 strain was identified as Enterococcus mundtii based on its sugar fermentation pattern and 16S rDNA sequence. The production of lactate by fermentation was optimised for the E. mundtii QU25 strain. The optimal pH and temperature for batch culturing were found to be 7.0°C and 43°C, respectively. E. mundtii QU 25 was able to metabolise a mixture of glucose and cellobiose simultaneously without apparent carbon catabolite repression. Moreover, under the optimised culture conditions, production of optically pure l-lactic acid (99.9%) increased with increasing cellobiose concentrations. This indicates that E. mundtii QU 25 is a potential candidate for effective lactic acid production from cellulosic hydrolysate materials.
为了经济高效地生产乳酸，需要一种能够有效利用其主要成分葡萄糖和纤维二糖的微生物。在从不同环境样本中分离的 631 株菌中，菌株 QU 25 能够从纤维二糖高效生产出具有高光学纯度的 l-(+)-乳酸。根据其糖发酵模式和 16S rDNA 序列，QU 25 菌株被鉴定为屎肠球菌。对屎肠球菌 QU25 菌株的发酵生产进行了优化。发现分批培养的最佳 pH 值和温度分别为 7.0°C 和 43°C。屎肠球菌 QU 25 能够同时代谢葡萄糖和纤维二糖的混合物，而没有明显的碳分解代谢物抑制。此外，在优化的培养条件下，随着纤维二糖浓度的增加，光学纯 l-乳酸（99.9%）的产量增加。这表明屎肠球菌 QU 25 是从纤维素水解物中有效生产乳酸的潜在候选菌株。
