Construction of Alkalotolerant Mn-superoxide Dismutase Engineered Strain and Its Expression Condition in Escherichia coli

The alkalotolerant Mn-superoxide dismutase encoding gene (Mn-sodA) from Bacillus sp. 110-2 was obtained, and inserted in pET-30a (+) to yield the recombinant expression vector pET-sodA. Over-expression of Mn-SOD in Escherichia coli BL21 (DE3) was achieved with pET-sodA, which was induced by Isopropyl-β-D-galactosidase (IPTG). SDS-PAGE analysis showed that an over-expressed recombinant product about 26.5 kD, consistent with the molecular weight predicted from gene sequence was produced. The recombinant protein was soluble in BL21(DE3). The specific activity of the recombinant enzyme Mn-SOD was 252 U/mg, which was 2.1 times than that of wild type. It indicated that the expression of Mn-sodA was high in E.coli. Furthermore, the recombinant en- zyme had a strong ability of alkali-resistance as wild enzyme. From the engineered strain-BL21 (pET-sodA), an alkali-resistance protein resources and a method to product the enzyme with extreme ability can be obtained.