title: Efficient production of optically pure L-lactic acid from food waste at ambient temperature by regulating key enzyme activity.
abstract: Bio-production of optically pure L-lactic acid from food waste has attracted much interest as it can treat organic wastes with simultaneous recovery of valuable by-products. However, the yield of L-lactic acid was very low and no optically pure L-lactic acid was produced in the literature due to (1) the lower activity of enzymes involved in hydrolysis and L-lactic acid generation, and (2) the participation of other enzymes related to D-lactic acid and acetic and propionic acids production. In this paper, a new strategy was reported for effective production of optically pure L-lactic acid from food waste at ambient temperature, i.e. via regulating key enzyme activity by sewage sludge supplement and intermittent alkaline fermentation. It was found that not only optically pure L-lactic acid was produced, but the yield was enhanced by 2.89-fold. The mechanism study showed that the activities of enzymes relevant to food waste hydrolysis and lactic acid production were enhanced, and the key enzymes related to volatile fatty acids and D-lactic acid generations were severally decreased or inhibited. Also, the microbes responsible for L-lactic acid production were selectively proliferated. Finally, the pilot-scale continuous experiment was conducted to testify the feasibility of this new technique.
authors.affiliation: College of Environmental Science and Engineering, Donghua University, 2999 North Renmin Road, Shanghai 201620, China; State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China. Electronic address: yg2chen@yahoo.com.
authors.forename: Yinguang
authors.initials: Y
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Shu
authors.initials: S
authors.lastname: Zhao
authors.affiliation: College of Environmental Science and Engineering, Donghua University, 2999 North Renmin Road, Shanghai 201620, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Xiong
authors.initials: X
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Jinyang
authors.initials: J
authors.lastname: Luo
authors.affiliation: College of Environmental Science and Engineering, Donghua University, 2999 North Renmin Road, Shanghai 201620, China.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Liu
mesh_terms: D004798:Enzymes / Q000378:metabolism*; D005285:Fermentation; D005502:Food; D019344:Lactic Acid / Q000737:chemistry / Q000378:metabolism*; D012722:Sewage; D062611:Solid Waste; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D004798:Enzymes; D012722:Sewage; D062611:Solid Waste; D019344:Lactic Acid
keywords: Food waste; Key enzyme activity; L-lactic acid fermentation; Waste activated sludge