An Effective and Simplified Fed-Batch Strategy for Improved 2,3-Butanediol Production by Klebsiella oxytoca

Abstract

Substrate concentration in 2,3-butanediol (2,3-BD) fermentation could not be controlled well in traditional feeding strategies, such as constant, impulse, and exponential feeding strategies. In the present study, fermentative 2,3-BD production by Klebsiella oxytoca was investigated under different batch and fed-batch strategies. The glucose-feedback fed-batch strategy was proved to be not effective for economical 2,3-BD production for the inability of timely feeding, leading that the bacteria reused 2,3-BD as carbon source for cell growth. Based on the phenomena that the byproducing acids caused the pH declining and the requirement of maintaining the pH at a proper level for both cell growth and 2,3-BD accumulation, an improved strategy of pH-stat fed-batch culture with glucose and sodium hydrate fed at the same time was established. Thus, the residual glucose concentration could be controlled through the adjustment of pH automatically. At last, efficient 2,3-BD production was fulfilled under this fed-batch strategy, and the highest 2,3-BD concentration, productivity, and yield were 127.9 g/l, 1.78 g/(l•h), and 0.48 g/g (2,3-BD/glucose), respectively, compared to 98.5 g/l, 1.37 g/(l•h), and 0.43 g/g obtained in glucose-feedback fed-batch strategy. This feeding strategy was simple and easy to operate and could be feasible for industrial 2,3-BD production in the future.