Enhanced 2,3-butanediol production by Klebsiella oxytoca using a two-stage agitation speed control strategy.

Batch fermentative production of 2,3-butanediol by Klebsiella oxytoca was investigated using various oxygen supply methods though varying agitation speed. Based on the analysis of three kinetic parameters including specific cell growth rate (micro), specific glucose consumption rate (q(s)) and specific 2,3-butanediol formation rate (q(p)), a two-stage agitation speed control strategy, aimed at achieving high concentration, high yield and high productivity of 2,3-butanediol, was proposed. At the first 15 h, agitation speed was controlled at 300 rpm to obtain high mu for cell growth, subsequently agitation speed was controlled at 200 rpm to maintain high q(p) for high 2,3-butanediol accumulation. Finally, the maximum concentration of 2,3-butanediol reached 95.5 g l(-1) with the yield of 0.478 g g(-1) and the productivity of 1.71 g l(-1)h(-1), which were 6.23%, 6.22% and 22.14% over the best results controlled by constant agitation speeds.