Metabolic regulation and optimization of oxygen supply enhance the 2,3-butanediol yield of the novel Klebsiella sp. isolate FSoil 024.

Abstract

Biogenic 2,3-butanediol (2,3-BDO) is a high-value-added compound that can be used as a liquid fuel and a platform chemical. Bioproduction of 2,3-BDO is an environmentally friendly choice. Three recombinant derivatives of the novel Klebsiella sp. isolate FSoil 024 (WT) were constructed via different strategies including deletion of lactate dehydrogenase by λ-Red homologous recombination technology, overexpression of the small-noncoding RNA RyhB and a combination of both. The 2,3-BDO productivity of the mutants increased by 61.3%-79%, and WT-Δldh/ryhB displayed the highest 2,3-BDO yield of 42.36mM after 24 h of shake-flask fermentation. Glucose was shown as the best carbon source for 2,3-BDO production by WT-Δldh/ryhB. In addition, higher oxygenation was favorable for ideal product synthesis. The maximal 2,3-BDO yield of WT and WT-Δldh/ryhB were increased by 23.3% and 52.5% respectively compared to the control group in the presence of 70% oxygen (V:V'=O2 :(O2 + N2 )). According to the present study, deletion of lactate dehydrogenase, RyhB overexpression, and manipulation of oxygen supply showed great impacts on cell growth, 2,3-BDO productivity and cellular metabolism of the novel isolated strain Klebsiella sp. FSoil 024. This work would also provide insights for promoting 2,3-BDO biosynthesis for industrial applications.