Resveratrol protects Lactobacillus reuteri against H2O2- induced oxidative stress and stimulates antioxidant defenses through upregulation of the dhaT gene.

Understanding of the mechanisms implicated in the protective role of probiotic bacteria is of the utmost scientific interest. This study provides original insight into the genetic and molecular basis of the responses of Lactobacillus reuteri PL503 against hydrogen peroxide (H2O2)-induced oxidative stress. Six experimental groups were considered depending on the addition and concentration of H2O2 and resveratrol: 1. CONTROL (L. reuteri in MRS broth); 2. H2O2 (L. reuteri in MRS broth + 0.5 mM H2O2); 3. LRES (L. reuteri in MRS broth + 20 μM resveratrol); 4. HRES (L. reuteri in MRS broth + 100 μM resveratrol); 5. H2O2-LRES (L. reuteri in MRS broth + 0.5 mM H2O2 + 20 μM resveratrol); 6. H2O2-HRES (L. reuteri in MRS broth + 0.5 mM H2O2 + 100 μM resveratrol). Three replicates were incubated at 37 °C for 24 h in microaerophilic conditions sampled at 12, 16, 20 and 24 h. The NADH-dependent-oxidoreductase encoded by the dhaT gene is a plausible candidate to be strongly implicated in the antioxidant response of L. reuteri. Resveratrol (100 μM) is found to protect L. reuteri against protein carbonylation plausibly through various mechanisms including direct scavenging of reactive oxygen species (ROS), upregulation of the dhaT gene and promoting the synthesis of sulfur containing compounds. The hypothesis formulated on the ability of L. reuteri to detoxify H2O2 and its underlying mechanism needs to be clarified. Furthermore, the consequences of protein carbonylation as a reflection of oxidative damage to bacteria and its role in the responses of bacteria to oxidative stress need to be further investigated.