Fig. 4

Time course of 2,3-BDO fermentation using pure glycerol and crude glycerol by K. oxytoca M1 ΔpduCΔldhA. a Fed-batch fermentation with pure glycerol. b Fed-batch fermentation with crude glycerol. The following symbols were used: dry cell weight unfilled triangle, residual glycerol unfilled square, 2,3-BDO filled circle, 1,3-PDO filled square and lactic acid filled triangle