Effects of pH and fermentation strategies on 2,3-butanediol production with an isolated Klebsiella sp. Zmd30 strain

•pH 6.0 was found most favorable for 2,3-BDO production among pH range of 4.5 to 9.0.•2,3-BDO production by Klebsiella sp. Zmd30 was most likely growth-associated.•Highest 2,3-BDO productivity (2.81g/l/h) was obtained with the continuous culture.•Fed-batch culture giving high BDO titer/yield is suitable for commercial production. This study examined the effects of pH-controlled and fermentation strategies on 2,3-butanediol (2,3-BDO) production by an isolated Klebsiella sp. Zmd30 strain. The pH value of 6.0 was found to be optimal among the investigated range of 4.5–9.0. In batch fermentation, the concentration, productivity and yield of 2,3-BDO were 57.17g/l, 1.59g/l/h and 82%, respectively. The 2,3-BDO production by Klebsiella sp. Zmd30 was found to be growth-associated. Higher 2,3-BDO concentration (110g/l) and yield (94%) was obtained by using fed-batch operation, but the productivity was lower (0.88g/l/h) as compared to that when using batch operation. The highest 2,3-BDO productivity of 2.81g/l/h was obtained with the continuous culture at a hydraulic retention time (HRT) of 12h. The results suggest that fed-batch operation might be most suitable for commercialized 2,3-BDO production, due to obtaining a high concentration and yield.