摘要：Serratia sp. T241, a newly isolated xylose-utilizing strain, produced three 2,3-butanediol (2,3-BD) stereoisomers. In this study, three 2,3-butanediol dehydrogenases (BDH1-3) and one glycerol dehydrogenase (GDH) involved in 2,3-BD isomers formation by Serratia sp. T241 were identified. In vitro conversion showed BDH1 and BDH2 could catalyzed (3 S )-acetoin and (3 R )-acetoin into (2 S ,3 S )-2,3-BD and meso -2,3-BD, while BDH3 and GDH exhibited the activities from (3 S )-acetoin and (3 R )-acetoin to meso -2,3-BD and (2 R ,3 R )-2,3-BD. Four encoding genes were assembled into E . coli with budA (acetolactate decarboxylase) and budB (acetolactate synthase), responsible for converting pyruvate into acetoin. E. coli expressing budAB - bdh1/2 produced meso -2,3-BD and (2 S ,3 S )-2,3-BD. Correspondingly, (2 R ,3 R )-2,3-BD and meso -2,3-BD were obtained by E. coli expressing budAB - bdh3 / gdh . These results suggested four enzymes might contribute to 2,3-BD isomers formation. Mutants of four genes were developed in Serratia sp. T241. Δ bdh1 led to reduced concentration of meso -2,3-BD and (2 S ,3 S )-2,3-BD by 97.7% and 87.9%. (2 R ,3 R )-2,3-BD with a loss of 73.3% was produced by Δ bdh3 . Enzyme activity assays showed the decrease of 98.4% and 22.4% by Δ bdh1 and Δ bdh3 compared with the wild strain. It suggested BDH1 and BDH3 played important roles in 2,3-BD formation, BDH2 and GDH have small effects on 2,3-BD production by Serratia sp. T241.
