L-lactic acid production from D-xylose withCandida sonorensis expressing a heterologouslactate dehydrogenase encoding gene

Microbial Cell Factories

Research

Pirkko Suominen¹  Merja Penttilä²  Laura Ruohonen²  Kari T Koivuranta²  Marilyn G Wiebe²  Marja Ilmén² 

[1] Cargill Biotechnology Research and Development, 15285 Minnetonka Blvd, 55345, Minnetonka, MN, USA;VTT Technical Research Centre of Finland, P. O. Box 1000, FI-02044 VTT, Espoo, Finland;

关键词: Candida sonorensis;    Yeast;    D-xylose;    L-lactic acid production;    Xylose isomerase;    Pyruvate decarboxylase;    Xylose reductase;    Xylitol dehydrogenase;   

DOI  :  10.1186/s12934-014-0107-2

 received in 2014-04-04, accepted in 2014-07-15,  发布年份 2014

来源: Springer

【 摘 要 】

BackgroundBioplastics, like polylactic acid (PLA), are renewable alternatives forpetroleum-based plastics. Lactic acid, the monomer of PLA, has traditionallybeen produced biotechnologically with bacteria. With genetic engineering, yeasthave the potential to replace bacteria in biotechnological lactic acidproduction, with the benefits of being acid tolerant and having simplenutritional requirements. Lactate dehydrogenase genes have been introduced tovarious yeast to demonstrate this potential. Importantly, an industrial lacticacid producing process utilising yeast has already been implemented. Utilisationof D-xylose in addition to D-glucose in production of biochemicals such aslactic acid by microbial fermentation would be beneficial, as it would allowlignocellulosic raw materials to be utilised in the production processes.ResultsThe yeast Candida sonorensis, whichnaturally metabolises D-xylose, was genetically modified to produce L-lacticacid from D-xylose by integrating the gene encoding L-lactic acid dehydrogenase(ldhL) from Lactobacillus helveticus into its genome. In microaerobic,CaCO3-buffered conditions a C. sonorensis ldhL transformant having two copies of theldhL gene produced31 g l−1 lactic acid from50 g l−1 D-xylose free of ethanol.Anaerobic production of lactic acid from D-xylose was assessed afterintroducing an alternative pathway of D-xylose metabolism, i.e. by adding axylose isomerase encoded by XYLA fromPiromyces sp. alone or together with thexylulokinase encoding gene XKS1 fromSaccharomyces cerevisiae. Strains werefurther modified by deletion of the endogenous xylose reductase encoding gene,alone or together with the xylitol dehydrogenase encoding gene. Strains ofC. sonorensis expressing xylose isomeraseproduced L-lactic acid from D-xylose in anaerobic conditions. The highestanaerobic L-lactic acid production (8.5 g l−1) wasobserved in strains in which both the xylose reductase and xylitol dehydrogenaseencoding genes had been deleted and the xylulokinase encoding gene fromS. cerevisiae was overexpressed.ConclusionsIntegration of two copies of the ldhL genein C. sonorensis was sufficient to obtaingood L-lactic acid production from D-xylose. Under anaerobic conditions, theldhL strain with exogenous xyloseisomerase and xylulokinase genes expressed and the endogenous xylose reductaseand xylitol dehydrogenase genes deleted had the highest L- lactic acidproduction.

【 授权许可】

CC BY   
© Koivuranta et al.; licensee BioMed Central 2014