College of Environmental and Chemical Engineering, Dalian University, Dalian 116622, People's Republic of China; Department of Biological Functions and Engineering, Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsh-ku, Kitakyushu 808-0196, Japan.
Bioresour Technol. 2014 Jan;151:28-35. doi: 10.1016/j.biortech.2013.10.022. Epub 2013 Oct 14.
The development of a low-cost polymer-grade L-lactic acid production process was achieved in this study. Excess sludge hydrolyzate (ESH) was chosen as nutrient source for the objective of reducing nutrient cost in lactic acid production. 1% of ESH had high performance in lactic acid production relative to 2g/l yeast extract (YE) while the production cost of ESH was much lower than that of YE, indicating ESH was a promising substitute of YE. By employing a thermophilic strain of Bacillus coagulans (NBRC 12583), non-sterilized batch and repeated batch L-lactic acid fermentation was successfully performed, and the optical purity of L-lactic acid accumulated was more than 99%. Moreover, the factors associated with cell growth and lactic acid fermentation was investigated through a two-stage lactic acid production strategy. Oxygen played an important role in cell growth, and the optimal condition for cell growth and fermentation was pH 7.0 and 50°C.
本研究成功开发了一种低成本的聚合物级 L-乳酸生产工艺。选择剩余污泥水解物（ESH）作为营养源，旨在降低乳酸生产中的营养成本。与 2g/L 酵母提取物（YE）相比，1%的 ESH 在乳酸生产中表现出很高的性能，而 ESH 的生产成本远低于 YE，表明 ESH 是 YE 的一种有前途的替代品。通过使用嗜热芽孢杆菌（NBRC 12583），成功地进行了未灭菌分批和重复分批 L-乳酸发酵，积累的 L-乳酸光学纯度超过 99%。此外，通过两段式乳酸生产策略研究了与细胞生长和乳酸发酵相关的因素。氧气在细胞生长中起着重要作用，细胞生长和发酵的最佳条件为 pH 7.0 和 50°C。
