Journal of Microbiology and Biotechnology 2012-04-01

Large increase in Leuconostoc citreum KM20 dextransucrase activity achieved by changing the strain/inducer combination in an E. coli expression system.

Jin-A Ko, Hyung Jae Jeong, Young Bae Ryu, Su-Jin Park, Young-Jung Wee, Doman Kim, Young-Min Kim, Woo Song Lee

Index: J. Microbiol. Biotechnol. 22(4) , 510-5, (2012)

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Abstract

A recombinant putative dextransucrase (DexT) was produced from Leuconostoc citreum KM20 as a 160 kDa protein, but its productivity was very low (264 U/l). For optimization, we examined enzyme activity in 7 Escherichia coli strains with inducer molecules such as lactose or IPTG. E. coli BL21-CodonPlus(DE3)-RIL exhibited the highest enzyme activity with lactose. Finally, DexT activity was remarkably increased by 12-fold under the optimized culture conditions of a cell density to start induction (OD₆₀₀) of 0.95, a lactose concentration of 7.5 mM, and an induction temperature of 17 degrees C. These results may effectively apply to the heterologous expression of other large DexT genes.