Vinod Kumar
The University of Nottingham, UK
Title: Production of 1,3-propanediol from glycerol by mutant Klebsiella pneumoniae J2B devoid of 2,3-butanediol formation
Biography
Biography: Vinod Kumar
Abstract
The 2,3-butanediol (BDO) is produced as a major byproduct during the production of 1,3- propanediol (PDO) from glycerol under limited aeration conditions by Klebsiella pneumoniae. In thepresent study, The BDO pathway genes, budA, budB, budC and budO (whole-bud operon), were deleted from K. pneumoniae J2B ΔldhA and the mutants were studied for glycerol metabolism and alcohols (PDO, BDO) production. Only the budO deletion mutant could completely abolish BDO production, but it exhibited serious reduction in cell growth and PDO production. By modifying culture medium such as increasing buffering capacity (from 29 mM phosphate to 100 mM phosphate) and adding bicarbonate (50 mM), the performance of the budO deletion mutant could be recovered to a similar level of the base strain (91.1 mM PDO under microaerobic condition) on flask scale. However, in fed-batch bioreactor experiment, the budO deletion mutant produced significantly less PDO (502 mM) than the base strain (753 mM). In addition, the budO deletion mutant produced significant amount of pyruvate (>73 mM) and lactate (>38 mM). The low PDO production in K. pneumoniae J2B ΔldhAΔbudO was attributed to the accumulation of glycolytic intermediates such as dihydroxyacetone and glyceraldehyde-3-phosphate, which are highly inhibitory to glycerol dehydratase.