Yokaryo Hiroto, Tokiwa Yutaka
Okinawa Prefectural Industrial Technology Center.
J Gen Appl Microbiol. 2014;60(6):270-5. doi: 10.2323/jgam.60.270.
Lactic acid bacteria that grow under alkaline conditions (pH 10) were isolated from various sources in Okinawa (Japan). These alkali-tolerant and alkaliphilic bacteria were classified as follows: Microbacterium sp. (1 strain), Enterococcus spp. (9 strains), Alkalibacterium spp. (3 strains), Exiguobacterium spp. (5 strains), Oceanobacillus spp. (3 strains) and Bacillus spp. (7 strains) by 16S rRNA gene sequencing. By fermentation, many strains were able to convert glucose into mainly L-(+)-lactic acid of high optical purity in alkaline broth. This result indicated that valuable L-(+)-lactic acid-producing bacteria could be isolated efficiently by screening under alkaline conditions. Six strains were selected and their ability to produce lactic acid at different initial pH was compared. Enterococcus casseliflavus strain 79w3 gave the highest lactic acid concentration. Lactic acid concentration and productivity were 103 g L(-1) (optical purity of 99.5% as L-isomer) and 2.2 g L(-1) h(-1), respectively when 129 g L(-1) of glucose was used by batch fermentation.
从日本冲绳的各种来源中分离出了能在碱性条件（pH 10）下生长的乳酸菌。这些耐碱和嗜碱细菌通过16S rRNA基因测序分类如下：微杆菌属（1株）、肠球菌属（9株）、嗜碱杆菌属（3株）、微小杆菌属（5株）、海洋芽孢杆菌属（3株）和芽孢杆菌属（7株）。通过发酵，许多菌株能够在碱性肉汤中将葡萄糖主要转化为光学纯度高的L-(+)-乳酸。该结果表明，通过在碱性条件下筛选，可以有效地分离出有价值的产L-(+)-乳酸的细菌。选择了6株菌株，并比较了它们在不同初始pH下产生乳酸的能力。卡氏黄色肠球菌79w3菌株产生的乳酸浓度最高。当通过分批发酵使用129 g L(-1)的葡萄糖时，乳酸浓度和产率分别为103 g L(-1)（L-异构体的光学纯度为99.5%）和2.2 g L(-1) h(-1)。
