Abstract
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 H2O2 at different concentrations (0, 1, 2, and 3 mM) on the physiological, morphological, and antioxidant properties of Pediococcus pentosaceus R1 and Lactobacillus fermentum R6 isolated from Harbin dry sausages. The increase in H2O2 concentration induced a significant increase in reactive oxygen species and a decrease in intracellular ATP levels (p < 0.05). Based on scanning electron microscopy, transmission electron microscopy, and electric conductivity analysis, H2O2 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. H2O2 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 (p < 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.
Highlights
Lactic acid bacteria (LAB) play a crucial role in many fermentation processes, as they control the growth of harmful bacteria and improve the sensory quality and texture of foods [4,5]
When LAB are used as functional starters, their resistance to oxidative stress is essential to the production of fermented foods
Metabolic disturbance and death of cells can occur when the rate of reactive oxygen species (ROS) production exceeds the antioxidant capacity of the LAB [30]
Summary
Lactic acid bacteria (LAB) are innocuous and beneficial microorganisms extensively used in a variety of fermented foods [1,2], and they are widely used in many functional fermented foods as bio-ingredients [3]. LAB play a crucial role in many fermentation processes, as they control the growth of harmful bacteria and improve the sensory quality and texture of foods [4,5]. Some specific strains of LAB have been demonstrated to have antioxidant potential and can capture and neutralize reactive oxygen species (ROS) to delay or prevent oxidation of fermented foods [6,7]. Many studies have illustrated that some probiotic LAB strains, especially Lactobacillus, can eliminate excessive
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