Abstract The Mn-superoxide dismutase encoding gene(Mn-sodA) from Bacillus sp. 110-2 was amplified by PCR. The Mn-SOD gene was inserted in pET-30a(+) to yield the recombinant expression vector pET-sodA. Over-expression of Mn-SOD in E.coli BL21(DE3) was achieved with pET-sodA, which was induced by Isopropyl-β-D-galactosidase(IPTG). SDS-PAGE analysis showed an over-expressed recombinant product at about 26.5 kDa, consistent with the molecular weight predicted from gene sequence. The expression of Mn-superoxide dismutase were also discussed. The recombinant protein was soluble in BL21(DE3). The specific activity of Mn-SOD was 252 U/mg, which was 2.1 times than wild type, so the Mn-sodA had a high expression in E.coli; Furthermore, the recombinant enzyme reserved the significant alkali-resistance of wild enzyme. From the engineered strain-BL21（pET-sodA）, we could obtain a protein resources and a methods to extreme-enzyme production.
