title: Production of d-lactic acid from hardwood pulp by mechanical milling followed by simultaneous saccharification and fermentation using metabolically engineered Lactobacillus plantarum.
abstract: This study focused on the process development for the d-lactic acid production from cellulosic feedstocks using the Lactobacillus plantarum mutant, genetically modified to produce optically pure d-lactic acid from both glucose and xylose. The simultaneous saccharification and fermentation (SSF) using delignified hardwood pulp (5-15% loads) resulted in the lactic acid titers of 55.2-84.6g/L after 72h and increased productivities of 1.77-2.61g/L/h. To facilitate the enzymatic saccharification of high-load pulp at a fermentation temperature, short-term (⩽10min) pulverization of pulp was conducted, leading to a significantly improved saccharification with the suppressed formation of formic acid by-product. The short-term milling followed by SSF resulted in a lactic acid titer of 102.3g/L, an optical purity of 99.2%, and a yield of 0.879g/g-sugars without fed-batch process control. Therefore, the process presented here shows promise for the production of high-titer d-lactic acid using the L. plantarum mutant.
authors.affiliation: Bio-energy Corporation, Research and Development Laboratory, 2-9-7 Minaminanamatsu, Amagasaki 660-0053, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Hama
authors.affiliation: Bio-energy Corporation, Research and Development Laboratory, 2-9-7 Minaminanamatsu, Amagasaki 660-0053, Japan.
authors.forename: Shino
authors.initials: S
authors.lastname: Mizuno
authors.affiliation: Bio-energy Corporation, Research and Development Laboratory, 2-9-7 Minaminanamatsu, Amagasaki 660-0053, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Kihara
authors.affiliation: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Ogino
authors.affiliation: Bio-energy Corporation, Research and Development Laboratory, 2-9-7 Minaminanamatsu, Amagasaki 660-0053, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Noda
authors.affiliation: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan. Electronic address: akondo@kobe-u.ac.jp.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
mesh_terms: D019149:Bioreactors / Q000382:microbiology; D002241:Carbohydrates; D002482:Cellulose / Q000737:chemistry* / Q000378:metabolism*; D005285:Fermentation / Q000502:physiology; D024861:Genetic Enhancement / Q000379:methods; D007220:Industrial Waste / Q000517:prevention & control; D019344:Lactic Acid / Q000096:biosynthesis* / Q000302:isolation & purification; D048191:Lactiplantibacillus plantarum / Q000502:physiology*; D014934:Wood / Q000737:chemistry* / Q000382:microbiology*
chemical_list: D002241:Carbohydrates; D007220:Industrial Waste; D019344:Lactic Acid; D002482:Cellulose
keywords: Ball milling; Kraft pulp; Pretreatment; d-Lactic acid