Enhanced Promoter Activity by Replenishment of Sigma Factor rpoE in Klebsiella pneumoniae

Abstract

Plasmid-dependent overexpression of enzyme(s) aims to divert carbon flux toward a desired compound. One drawback of this strategy is compromise of growth due to massive consumption of host resources. Here we show that replenishment of sigma factor rpoE improves the growth of Klebsiella pneumoniae. The gene rpoE was expressed alone or coexpressed with Ald4 (an aldehyde dehydrogenase from Saccharomyces cerevisiae) in K. pneumoniae. We found that the Ald4 activity was higher in the strain coexpressing Ald4 and rpoE (32.3 U/mg) than that expressing Ald4 alone (29.9 U/mg). Additionally, under shake-flask conditions, the strain coexpressing Ald4 and rpoE produced 0.5 g 3-hydroxypropionic acid (3-HP) and 9.8 g 1,3-propanediol (1,3-PD) per liter in 24 h, which were 1.6-and 0.85-fold enhancement, respectively, compared to those expressing Ald4 alone. Notably, under nonoptimized bioreactor conditions, the strain coexpressing Ald4 and rpoE produced 13.5 g 3-HP and 37.8 g 1,3-PD per liter with glycerol conversion ratio of 0.45 mol/mol. These results indicate that replenishment of rpoE enhanced promoter activity and stimulated glycerol consumption.

Biorefinery for Glycerol Rich Biodiesel Industry Waste

“…Further optimization of the bioprocess has lead to 1,3-PDO yield of 56 g/L [16]. K. pneumoniae co-expressing ald4 and rpoE produced 9.8 g 1,3-PDO/L over a period of 24 h, which was an enhancement of 0.85-fold over strain expressing only ald4 [17]. Klebsiella oxytoca M1 could convert CG more effectively than pure glycerol for producing 2,3-butanediol (2,3-BDO) (73.8 g/L).…”

Application of the 3'-Untranslated Region of Messenger RNA from Measles Virus Matrix Protein as an RNA Stabilizer: Implications in Pharmaceutical Biotechnology

“…Owing to the compiling research to find new elements, the number of potentially useful vector elements is expanding (Kado, 2014;Kaufman, 2000). The utilization of strong promoters and the design and configuration of the plasmid are examples of methodologies that have been inspected before and appeared to enhance the profits (Hung et al, 2010;Chen, Li, & Tian, 2016).…”