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Updated: May 6, 2026

Light-Controlled Fermentations for Microbial Chemical and Protein Production
Published on: March 22, 2022
Open fermentative production of L-lactic acid with high optical purity by thermophilic Bacillus coagulans using
Kedong Ma1, Toshinari Maeda, Huiyan You
1College 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.
Abstract:
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.
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