Institute for Stem Cells and Tissue Engineering, College of Pharmacy, Binzhou Medical University, Yantai, People's Republic of China.
Bioresour Technol. 2010 Oct;101(19):7570-6. doi: 10.1016/j.biortech.2010.04.037. Epub 2010 May 21.
A sodium lactate tolerant mutant strain named Bacillus sp. Na-2 was obtained and applied to sodium hydroxide-based L-lactic acid (LA) production process. The influences of aeration and pH were investigated to further improve the resistance of strain Na-2 against sodium lactate stress and to obtain the most efficient L-LA production process. Although mild aeration was favorable for cell growth and L-LA production, vigorous aeration resulted in a metabolic shift from homolactic to mixed-acid/acetoin fermentation. Therefore, a two-stage aeration control strategy was employed. Optimum pH was found to be 6.0. A total of 106.0 g/l L-LA was produced in 30 h by Bacillus sp. Na-2 using sodium hydroxide as neutralizing agent. Productivity, conversion rate and optical purity were 3.53 g/l/h, 94% and 99.5%, respectively. The remarkable fermentation traits of Bacillus sp. Na-2 and the environment-friendly characteristics of NaOH-based process represent new insight for industrial scale production of L-LA.
一株耐乳酸钠突变株被命名为 Bacillus sp. Na-2，并将其应用于基于氢氧化钠的 L-乳酸（LA）生产工艺中。考察了通气和 pH 值的影响，以进一步提高菌株 Na-2 对乳酸钠胁迫的抗性，并获得最有效的 L-LA 生产工艺。虽然轻度通气有利于细胞生长和 L-LA 的生产，但剧烈通气会导致代谢从同型乳酸发酵转变为混合酸/乙酰醇发酵。因此，采用了两段式通气控制策略。发现最佳 pH 值为 6.0。 Bacillus sp. Na-2 使用氢氧化钠作为中和剂，在 30 h 内生产出 106.0 g/L 的 L-LA。产物得率、转化率和光学纯度分别为 3.53 g/L/h、94%和 99.5%。 Bacillus sp. Na-2 的显著发酵特性和基于 NaOH 的工艺的环保特性为 L-LA 的工业化生产提供了新的思路。
