Isolation and characterization of the new Klebsiella pneumoniae J2B strain showing improved growth characteristics with reduced lipopolysaccharide formation

Abstract

Klebsiella pneumoniae is a suitable biocatalyst for the production of 1,3-propanediol (1,3-PDO) and 3-hydroxypropionic acid (3-HP) from glycerol. However, its commercial applications have been impeded due to its poor growth characteristics and the excessive production of lipopolysaccharide (LPS). To overcome these limitations, a new K. pneumoniae J2B (KpJ2B) strain was isolated from municipal waste anaerobic digester samples. The shake flask cultivation of this new strain under aerobic conditions showed a specific growth rate of 0.92/h, which is 1.13 times higher than that achieved using the well studied K. pneumoniae DSMZ2026 (KpDSMZ). When the new strain was grown in a bioreactor under aerobic conditions using a fed-batch mode for 36 h, the biomass concentration (4.03 g/L CDW) and productivity (0.15 g/L/h) were almost 2.2 times higher than the corresponding values with KpDSMZ. Growth was accompanied by the production of 1,3-PDO (186 mM), lactic acid (235 mM), ethanol (170 mM), and acetic acid (92.2 mM) at significant levels, indicating the resistance of the strain to the inhibitory effects of these metabolites. A comparison of the SEM images and 2-keto-3-deoxyoctonate content (KpJ2B, 1.4 mu g/g CDW; KpDSMZ, 1.9 mu g/g CDW) confirmed the lower LPS content in the KpJ2B strain. Furthermore, this new isolate exhibited higher sensitivity towards a range of antibiotics and better sedimentation properties than the KpDSMZ strain. This suggests that KpJ2B is an attractive strain for industrial applications.