Large increase in Leuconostoc citreum KM20 dextransucrase activity achieved by changing the strain/inducer combination in an E. coli expression system |
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Authors: | Ko Jin-A Jeong Hyung Jae Ryu Young Bae Park Su-Jin Wee Young-Jung Kim Doman Kim Young-Min Lee Woo Song |
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Affiliation: | Infection Control Material Research Center, Korea Research Institute of Bioscience and Biotechnology-KRIBB, Jeongeup 580-185, Korea. |
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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 (OD???) 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. |
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