Physiological, Morphological and Antioxidant Responses of R1 and R6 Isolated from Harbin Dry Sausages to Oxidative Stress

As functional starter cultures and potential probiotics, the ability of lactic acid bacteria to resist oxidative stress is essential to maintain viability and functional properties. This study investigates the effects of HO at different concentrations (0, 1, 2, and 3 mM) on the physiological, morphological, and antioxidant properties of R1 and R6 isolated from Harbin dry sausages. The increase in HO concentration induced a significant increase in reactive oxygen species and a decrease in intracellular ATP levels ( < 0.05). Based on scanning electron microscopy, transmission electron microscopy, and electric conductivity analysis, HO stress caused cell deformation, the destruction of cell membrane integrity, partial loss of the cytoplasm, and an increase in the cell conductivity of both strains. HO stress with 1 mM or 2 mM concentrations could effectively improve the scavenging rates of free radicals, the activities of superoxide dismutase and glutathione peroxide, and the total antioxidant capacity of both strains ( < 0.05). In conclusion, an appropriate oxidative stress contributed to the activation of the antioxidant defense system of both strains, conferred strains a better effect in inhibiting the oxidation of fermented foods, and improved the health of the host.