title: Open fermentative production of L-lactic acid with high optical purity by thermophilic Bacillus coagulans using excess sludge as nutrient.
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.
authors.affiliation: 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. Electronic address: makedongdl@yahoo.co.jp.
authors.forename: Kedong
authors.initials: K
authors.lastname: Ma
authors.forename: Toshinari
authors.initials: T
authors.lastname: Maeda
authors.forename: Huiyan
authors.initials: H
authors.lastname: You
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Shirai
mesh_terms: D000332:Aerobiosis / Q000187:drug effects; D000693:Anaerobiosis / Q000187:drug effects; D001407:Bacillus / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D061249:Batch Cell Culture Techniques; D001709:Biotechnology / Q000379:methods*; D049109:Cell Proliferation / Q000187:drug effects; D005240:Feasibility Studies; D005285:Fermentation / Q000187:drug effects; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D019344:Lactic Acid / Q000096:biosynthesis*; D009584:Nitrogen / Q000494:pharmacology; D055620:Optical Phenomena; D010100:Oxygen / Q000494:pharmacology; D012722:Sewage / Q000382:microbiology*; D013696:Temperature
chemical_list: D012722:Sewage; D019344:Lactic Acid; D005947:Glucose; D009584:Nitrogen; D010100:Oxygen
keywords: Bacillus coagulans; Excess sludge hydrolyzate (ESH); Open fermentation; l-Lactic acid