title: d-lactic acid production from renewable lignocellulosic biomass via genetically modified Lactobacillus plantarum.
abstract: d-lactic acid is of great interest because of increasing demand for biobased poly-lactic acid (PLA). Blending poly-l-lactic acid with poly-d-lactic acid greatly improves PLA's mechanical and physical properties. Corn stover and sorghum stalks treated with 1% sodium hydroxide were investigated as possible substrates for d-lactic acid production by both sequential saccharification and fermentation and simultaneous saccharification and cofermentation (SSCF). A commercial cellulase (Cellic CTec2) was used for hydrolysis of lignocellulosic biomass and an l-lactate-deficient mutant strain Lactobacillus plantarum NCIMB 8826 ldhL1 and its derivative harboring a xylose assimilation plasmid (ΔldhL1-pCU-PxylAB) were used for fermentation. The SSCF process demonstrated the advantage of avoiding feedback inhibition of released sugars from lignocellulosic biomass, thus significantly improving d-lactic acid yield and productivity. d-lactic acid (27.3 g L(-1) ) and productivity (0.75 g L(-1) h(-1) ) was obtained from corn stover and d-lactic acid (22.0 g L(-1) ) and productivity (0.65 g L(-1) h(-1) ) was obtained from sorghum stalks using ΔldhL1-pCU-PxylAB via the SSCF process. The recombinant strain produced a higher concentration of d-lactic acid than the mutant strain by using the xylose present in lignocellulosic biomass. Our findings demonstrate the potential of using renewable lignocellulosic biomass as an alternative to conventional feedstocks with metabolically engineered lactic acid bacteria to produce d-lactic acid. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:271-278, 2016.
authors.affiliation: Dept. of Grain Science and Industry, Bioprocessing and Renewable Energy Laboratory, Kansas State University, Manhattan, KS, 66506.
authors.forename: Yixing
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Dept. of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, 66506.
authors.forename: Amit
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Dept. of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, 66506.
authors.forename: Philip R
authors.initials: PR
authors.lastname: Hardwidge
authors.affiliation: Dept. of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada, Kobe, 657-8501, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Dept. of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada, Kobe, 657-8501, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
authors.affiliation: Dept. of Grain Science and Industry, Bioprocessing and Renewable Energy Laboratory, Kansas State University, Manhattan, KS, 66506A.|Dept. of Chemical Engineering, Kansas State University, Manhattan, KS, 66506.
authors.forename: Praveen V
authors.initials: PV
authors.lastname: Vadlani
mesh_terms: D018533:Biomass; D006868:Hydrolysis; D019344:Lactic Acid / Q000096:biosynthesis* / Q000737:chemistry; D048191:Lactiplantibacillus plantarum / Q000235:genetics / Q000378:metabolism*; D008031:Lignin / Q000378:metabolism*; D060847:Metabolic Engineering
chemical_list: C036909:lignocellulose; D019344:Lactic Acid; D008031:Lignin
keywords: d-lactic Acid; fermentation; lignocellulosic biomass; metabolically engineered L. plantarum; xylose assimilation plasmid