title: Contributory roles of two l-lactate dehydrogenases for l-lactic acid production in thermotolerant Bacillus coagulans.
abstract: Thermotolerant Bacillus coagulans is considered to be a more promising producer for bio-chemicals, due to its capacity to withstand harsh conditions. Two L-lactate dehydrogenase (LDH) encoding genes (ldhL1 and ldhL2) and one D-LDH encoding gene (ldhD) were annotated from the B. coagulans DSM1 genome. Transcriptional analysis revealed that the expression of ldhL2 was undetectable while the ldhL1 transcription level was much higher than that of ldhD at all growth phases. Deletion of the ldhL2 gene revealed no difference in fermentation profile compared to the wild-type strain, while ldhL1 single deletion or ldhL1ldhL2 double deletion completely blocked L-lactic acid production. Complementation of ldhL1 in the above knockout strains restored fermentation profiles to those observed in the wild-type strain. This study demonstrates ldhL1 is crucial for L-lactic acid production and NADH balance in B. coagulans DSM1 and lays the fundamental for engineering the thermotolerant B. coagulans strain as a platform chemicals producer.
authors.affiliation: CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.|School of Food Engineering and Biological Technology, Tianjin University of Science &Technology, Tianjin 300457, China.
authors.forename: Lifan
authors.initials: L
authors.lastname: Sun
authors.affiliation: CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Caili
authors.initials: C
authors.lastname: Zhang
authors.affiliation: College of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, China.
authors.forename: Pengcheng
authors.initials: P
authors.lastname: Lyu
authors.affiliation: School of Food Engineering and Biological Technology, Tianjin University of Science &Technology, Tianjin 300457, China.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Wang
authors.affiliation: CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Limin
authors.initials: L
authors.lastname: Wang
authors.affiliation: CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Yu
mesh_terms: D000070000:Bacillus coagulans / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D005285:Fermentation; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D007770:L-Lactate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism*; D058977:Molecular Sequence Annotation
chemical_list: D001426:Bacterial Proteins; D019344:Lactic Acid; D007770:L-Lactate Dehydrogenase