Anaerobic growth defect of pyruvate formate lyase (PFL)-deficient Klebsiella pneumoniae limits its industrial application, and the reason for this growth defect was analyzed in this study. The obtained evidences, combined with normal intracellular redox status and no further inhibition by adhE deletion, strongly suggested that growth defect in PFL-deficient K. pneumoniae was probably caused by lack of carbon flux from pyruvate to acetyl-CoA (AcCoA). Correspondingly, the anaerobic growth of PFL-deficient K. pneumoniae was promoted by deletion of pdhR, a negative transcriptional regulator gene for AcCoA generation. Through the regulation of pdhR deletion, the PFL-deficient K. pneumoniae exhibited highly efficient 1,3-propanediol production. Besides, in a 2-L fed-batch fermentation process, the cell growth of PFL-deficient K. pneumoniae strain almost recovered, when compared with that of the normal strain, and the 1,3-propanediol yield increased by 14%, while the byproducts acetate and 2,3-butanediol contents decreased by 29% and 24%, respectively.
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http://dx.doi.org/10.1007/s00284-019-01795-5 | DOI Listing |
J Microbiol Biotechnol
May 2020
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, P.R. China.
To determine the role of pyruvate dehydrogenase complex (PDHC) in , the growth and metabolism of PDHC-deficient mutant in glycerol-based medium were analyzed and compared with those of other strains. Under aerobic conditions, the PDHC activity was fourfold higher than that of pyruvate formate lyase (PFL), and blocking of PDHC caused severe growth defect and pyruvate accumulation, indicating that the carbon flux through pyruvate to acetyl coenzyme A mainly depended on PDHC. Under anaerobic conditions, although the PDHC activity was only 50% of that of PFL, blocking of PDHC resulted in more growth defect than blocking of PFL.
View Article and Find Full Text PDFCurr Microbiol
January 2020
State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, People's Republic of China.
Anaerobic growth defect of pyruvate formate lyase (PFL)-deficient Klebsiella pneumoniae limits its industrial application, and the reason for this growth defect was analyzed in this study. The obtained evidences, combined with normal intracellular redox status and no further inhibition by adhE deletion, strongly suggested that growth defect in PFL-deficient K. pneumoniae was probably caused by lack of carbon flux from pyruvate to acetyl-CoA (AcCoA).
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