Production of high levels of 2,3-butanediol from renewable crude glycerol by Klebsiella pneumoniae GEM167 using metabolic engineering and control of oxygen transfer efficiency

Abstract

Numerous industries use 2,3-butanediol as a bulk chemical. This study aimed to develop a technique for the commercial production of 2,3-butanediol from glycerol using K. pneumoniae GEM167 strain with enhanced oxidative pathways. We developed K. pneumoniae GEM167ΔadhEΔldhA, a strain that has decreased production of competitive metabolites (ethanol and lactate) and increased production of 2,3-butanediol. We investigated the correlation between the oxygen transfer coefficient and 2,3-butanediol production by modifying the agitation speed and aeration rate. K. pneumoniae GEM167ΔadhEΔldhA provided a high titer (102.9 ± 3.1 g/L) and productivity (2.14 ± 0.06 g/L/h) of 2,3-butanediol with no detectable 1,3-propaendiol production under specific culture conditions (37 °C, 700 rpm, 2.0 vvm, and pH 6.0). To the best of our knowledge, the productivity of 2,3-butanediol from glycerol in this study is the highest yet reported. And the substitution with crude glycerol enhanced the titer (105.3 ± 2.8 g/L) and productivity (2.19 ± 0.06 g/L/h) of 2,3-butanediol.