Enhancement of (R)-1,3-butanediol production by engineered Escherichia coli using a bioreactor system with strict regulation of overall oxygen transfer coefficient and pH

Abstract

(R)-1,3-butanediol ((R)-1,3-BD) is an important substrate for the synthesis of industrial chemicals. Despite its large demand, a bioprocess for the efficient production of 1,3-BD from renewable resources has not been developed. We previously reported the construction of recombinant Escherichia coli that could efficiently produce (R)-1,3-BD from glucose. In this study, the fermentation conditions were optimized to further improve 1,3-BD production by the recombinant strain. A batch fermentation was performed with an optimized overall oxygen transfer coefficient (82.3 h-1 ) and pH (5.5); the 1,3-BD concentration reached 98.5 mM after 36 h with high-yield (0.444 mol (mol glucose)-1) and a high maximum production rate (3.63 mM h-1). In addition, a fed-batch fermentation enabled the recombinant strain to produce 174.8 mM 1,3-BD after 96 h cultivation with a yield of 0.372 mol (mol glucose)-1, a maximum production rate of 3.90 mM h-1, and a 98.6% enantiomeric excess (% ee) of (R)-1,3-BD.