Abstract:To analyze the antioxidant properties of Lactobacillus and its relationship with katA gene. Six strains of Lactobacillus from naturally fermented meat products were selected as the research objects, and were evaluated by 1,1-diphenyl-2-picrylhydrazol (DPPH), hydroxyl (·OH), superoxide anion (O2-·) free radical scavenging rate, H2O2 tolerance and katA gene expression. The results showed that the main active substances for scavenging ·OH radicals were cell and intracellular substances, while scavenging DPPH and O2-· radicals were mainly metabolites of lactic acid bacteria. The scavenging ability of TR1-1-3 on the three kinds of free radicals was relatively strong, while the scavenging rate of ·OH and O2-· of strain X31 was the lowest and the difference was significant (P<0.05) compared with TR1-1-3. In addition to strain X31, other experimental strains had a certain tolerance to H2O2 in the range of 0-1.0 mmol/L H2O2 concentration, and the tolerance gradually increased with the extension of the culture time within 12-48 hours. The katA gene of strain X31 with low free radical clearance and H2O2 tolerance was negative by specific PCR, while all other strains were positive. This study found that lactic acid bacteria antioxidant capacity has strain specificity, through the apparent data of the scavenging rate of the free radicals of O2-·, ·OH, DPPH and the tolerance to H2O2 of the lactic acid bacteria, combined with the expression of katA gene, it can be used as the detection method for the determination of anti-oxidation lactic acid bacteria. The results can provide theoretical guidance and technical support for the development and application of high-quality strain resources.