Roles of superoxide dismutase and catalase of Staphylococcus xylosus in the inhibition of linoleic acid oxidation.

Staphylococcus xylosus used as starter culture in sausages decreases the level of volatile organic compounds arising from lipid oxidation and so contributes to the aroma by avoiding rancidity. The aim of this study was to characterize the roles of catalase and superoxide dismutase (SOD) in the inhibition of free fatty acid oxidation by comparing antioxidant capacity of the S. xylosus wild-type strain with those of the katA mutant and the sod mutant. Antioxidant capacity was determined by measuring the volatile organic compounds and the conjugated diene hydroperoxides arising from linoleic acid oxidation. The three strains inhibited the oxidation of linoleic acid. However, the katA mutant, and especially the sod mutant, had less antioxidant capacity than the S. xylosus wild-type strain. Thus both catalase and SOD of S. xylosus contributed to the inhibition of lipid oxidation.