title: Novel pH control strategy for efficient production of optically active l-lactic acid from kitchen refuse using a mixed culture system.
abstract: Uninvestigated control factors of meta-fermentation, the fermentative production of pure chemicals and fuels in a mixed culture system, were examined for production of optically pure l-lactic acid (LA) from food waste. In meta-fermentations by pH swing control, l-LA production with 100% optical purity (OPl-LA) was achieved even using unsterilized model kitchen refuse medium with preferential proliferation of l-LA-producing Bacillus coagulans, a minor member in the seed, whereas agitation decreased OPl-LA drastically. pH constant control shortened the fermentation time but decreased OPl-LA and LA selectivity (SLA) by stimulating growth of heterofermentative Bacillus thermoamylovorans. Deliberately switching from pH swing control to constant control exhibited the best performance for l-LA production: maximum accumulation, 39.2gL(-1); OPl-LA, 100%; SLA, 96.6%; productivity, 1.09gL(-1)h(-1). These results present a novel pH control strategy for efficient l-LA production in meta-fermentation based on a concept different from that of pure culture systems.
authors.affiliation: Laboratory of Soil and Environmental Microbiology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan; Laboratory of Microbial Environmental Protection, Tropical Microbiology Unit, Center for International Education and Research of Agriculture, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Tashiro
authors.affiliation: Laboratory of Soil and Environmental Microbiology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Shota
authors.initials: S
authors.lastname: Inokuchi
authors.affiliation: Laboratory of Soil and Environmental Microbiology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Pramod
authors.initials: P
authors.lastname: Poudel
authors.affiliation: Laboratory of Soil and Environmental Microbiology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Okugawa
authors.affiliation: Japan Eco-Science (Nikkan Kagaku) Co. Ltd, 11-2 Shiomigaokacho, Chuo-ku, Chiba 260-0034, Japan; Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Chiba 263-8522, Japan.
authors.forename: Hirokuni
authors.initials: H
authors.lastname: Miyamoto
authors.affiliation: Miroku Co. Ltd, Iwaya 706-27, Kitsuki, Oita 873-0006, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Miayamoto
authors.affiliation: Laboratory of Soil and Environmental Microbiology, Division of Systems Bioengineering, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School of Bioresources and Bioenvironmental Sciences, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan; Laboratory of Microbial Environmental Protection, Tropical Microbiology Unit, Center for International Education and Research of Agriculture, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan. Electronic address: kensak@agr.kyushu-u.ac.jp.
authors.forename: Kenji
authors.initials: K
authors.lastname: Sakai
mesh_terms: D001407:Bacillus; D019149:Bioreactors / Q000382:microbiology*; D005285:Fermentation; D005735:Garbage; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000096:biosynthesis*; D012037:Refuse Disposal / Q000379:methods*
chemical_list: D019344:Lactic Acid
keywords: Kitchen refuse; Mixed culture; Novel pH control strategy; l-lactic acid production