Dietary Supplementation With a Bacillus Superoxide Dismutase Protects Against γ-Radiation-induced Oxidative Stress and Ameliorates Dextran Sulphate Sodium-induced Ulcerative Colitis in Mice.

BACKGROUND AND AIMS: Commercial superoxide dismutase [SOD] is derived from melon extract and has a potential as a dietary supplement due to its beneficial antioxidative effects. We aimed to improve the productivity of SOD compared with plant SOD by using a generally regarded as safe [GRAS] microorganism, Bacillus amyloliquefaciens, and assess its antioxidative effect using γ-radiation- and dextransulphate sodium [DSS]-induced oxidative models in mice.

METHODS

We identified the sodA gene encoding manganese-containing SODs [Mn-SOD] in B. amyloliquefaciens, constructed a Mn-SOD deficient mutant, and screened a high-SOD-producing strain. We compared the antioxidative effect of orally administered enteric-coated SOD protein partially purified from B. amyloliquefaciens with wild-type and high-SOD-producing strain spores. The effect of SOD on DSS-induced colitis was also investigated. Colonic inflammation was assessed using disease activity index, macroscopic and histological damage scores, antioxidant enzyme activities, and inflammatory cytokines.

RESULTS

The SOD activity of B. amyloliquefaciens is derived from secreted Mn-SOD encoded by the sodA gene, as shown by comparing sodA knock-out mutant spores with wild-type and high-SOD-producing spores. Enteric-coated SOD of B. amyloliquefaciens appears to be effective in reducing oxidative stress in γ-radiation- and DSS-induced mouse models. Co-administration of SOD with wild-type B. amyloliquefaciens or high-SOD-producer strain spores showed a synergistic effect. SOD enzyme and B. amyloliquefaciens spores contribute to the reduction of oxidative stress and inflammatory response in DSS-induced colitis.

CONCLUSIONS

Mn-SOD of B. amyloliquefaciens could be another source of SOD supplement and may be useful to prevent and treat ulcerative colitis.