Separate expression and co-expression of MTSase and MTHase from Arthrobacter ramosus S34 in Escherichia coli BL21(DE3)

Maltooligosyl trehalose synthase (MTSase) and maltooligosyl trehalose hydrolase (MTHase) are used to produce trehalose, a disaccharide of interest to many different industries, from starch. MTSase and MTHase from Arthrobacter ramosus S34 were first produced using separate Escherichia coli BL21(DE3) strains. The activities obtained in a 3-L fermenter under optimized conditions were 1608.3 U mL −1 and 8766.2 U mL −1 , respectively. Then, MTSase and MTHase were co-produced in E. coli BL21(DE3) using a co-expression construct. After optimizing induction conditions, the MTSase and MTHase activities produced by the superior strain reached 1827.4 U mL −1 and 2944.9 U mL −1 , respectively. When the co-produced enzymes were used to synthesize trehalose from starch, a conversion rate identical to that achieved using separately produced enzymes (about 67%) was obtained. This is the first describing the co-production of the MTSase and MTHase in a 3-L fermentor. The results represented the highest MTSase production level reported to date, and the MTHase activity from co-production was sufficient for trehalose synthesis. Using co-produced enzymes during trehalose synthesis would lower costs without sacrificing yield. Therefore, this study provided a foundation for the industrial synthesis of trehalose using co-produced enzymes.