title: Membrane-integrated fermentation system for improving the optical purity of D-lactic acid produced during continuous fermentation.
abstract: This report describes the production of highly optically pure D-lactic acid by the continuous fermentation of Sporolactobacillus laevolacticus and S. inulinus, using a membrane-integrated fermentation (MFR) system. The optical purity of D-lactic acid produced by the continuous fermentation system was greater than that produced by batch fermentation; the maximum value for the optical purity of D-lactic acid reached 99.8% enantiomeric excess by continuous fermentation when S. leavolacticus was used. The volumetric productivity of the optically pure D-lactic acid was about 12 g/L/h, this being approximately 11-fold higher than that obtained by batch fermentation. An enzymatic analysis indicated that both S. laevolacticus and S. inulinus could convert L-lactic acid to D-lactic acid by isomerization after the late-log phase. These results provide evidence for an effective bio-process to produce D-lactic acid of greater optical purity than has conventionally been achieved to date.
authors.affiliation: New Frontiers Research Laboratories, Toray Industries, Inc., Kamakura, Kanagawa, Japan
authors.forename: Hideki
authors.initials: H
authors.lastname: Sawai
authors.forename: Kyungsu
authors.initials: K
authors.lastname: Na
authors.forename: Nanami
authors.initials: N
authors.lastname: Sasaki
authors.forename: Takashi
authors.initials: T
authors.lastname: Mimitsuka
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Minegishi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Henmi
authors.forename: Katsushige
authors.initials: K
authors.lastname: Yamada
authors.forename: Sakayu
authors.initials: S
authors.lastname: Shimizu
authors.forename: Tetsu
authors.initials: T
authors.lastname: Yonehara
mesh_terms: D056449:Bacillales / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D002462:Cell Membrane / Q000378:metabolism*; D005285:Fermentation; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D019344:Lactic Acid / Q000096:biosynthesis* / Q000737:chemistry; D007778:Lactobacillus / Q000378:metabolism; D055620:Optical Phenomena; D013237:Stereoisomerism
chemical_list: D019344:Lactic Acid; D007770:L-Lactate Dehydrogenase