title: D-Lactic acid biosynthesis from biomass-derived sugars via Lactobacillus delbrueckii fermentation.
abstract: Poly-lactic acid (PLA) derived from renewable resources is considered to be a good substitute for petroleum-based plastics. The number of poly L-lactic acid applications is increased by the introduction of a stereocomplex PLA, which consists of both poly-L and D-lactic acid and has a higher melting temperature. To date, several studies have explored the production of L-lactic acid, but information on biosynthesis of D-lactic acid is limited. Pulp and corn stover are abundant, renewable lignocellulosic materials that can be hydrolyzed to sugars and used in biosynthesis of D-lactic acid. In our study, saccharification of pulp and corn stover was done by cellulase CTec2 and sugars generated from hydrolysis were converted to D-lactic acid by a homofermentative strain, L. delbrueckii, through a sequential hydrolysis and fermentation process (SHF) and a simultaneous saccharification and fermentation process (SSF). 36.3 g L(-1) of D-lactic acid with 99.8 % optical purity was obtained in the batch fermentation of pulp and attained highest yield and productivity of 0.83 g g(-1) and 1.01 g L(-1) h(-1), respectively. Luedeking-Piret model described the mixed growth-associated production of D-lactic acid with a maximum specific growth rate 0.2 h(-1) and product formation rate 0.026 h(-1), obtained for this strain. The efficient synthesis of D-lactic acid having high optical purity and melting point will lead to unique stereocomplex PLA with innovative applications in polymer industry.
authors.affiliation: Department of Grain Science and Industry, Bioprocessing and Renewable Energy Laboratory, Kansas State University, Manhattan, KS, USA.
authors.forename: Yixing
authors.initials: Y
authors.lastname: Zhang
authors.forename: Praveen V
authors.initials: PV
authors.lastname: Vadlani
mesh_terms: D018533:Biomass; D050260:Carbohydrate Metabolism; D002241:Carbohydrates; D005285:Fermentation; D006868:Hydrolysis; D019344:Lactic Acid / Q000096:biosynthesis*; D048668:Lactobacillus delbrueckii / Q000254:growth & development / Q000378:metabolism*
chemical_list: D002241:Carbohydrates; D019344:Lactic Acid