Characterization of a 2,3-Butanediol Producing Bacterial Strain and Optimization of Fermentation Medium

A bacterial strain G12 capable of producing high content of 2,3- butanediol (2,3-BD, BD) was isolated from raw milk samples. With the analysis of its 16S rRNA gene sequence, strain G12 was identified as Serratia marcescens. Carbon source evaluation experiments showed that with glycerol as carbon source, strain G12 produced relatively high amount of 2,3-BD and the lowest amount of byproduct acetoin among the tested carbon sources. Furthermore, the optimal fermentation medium was determined by single factor experiments and orthogonal experimental design, and it was composed of glycerin 130 g/L, peptone 16 g/L, yeast extract 5 g/L, K2HPO4 1 g/L, and MnSO4·7H2O 0.025 g/L. Confirmation experiments were also performed. The final yield of 2,3-BD in the shaking-flask was up to 37.400 g/L, and the substrate conversion rate was 79.62 % of the theoretical value.