Screening and in Vitro Tolerance Analysis of Lactobacillus plantarum with High Antioxidant Activity in Traditional Fermented Food of Northeast China

In order to obtain Lactobacillus plantarum with high antioxidant activity,75 strains of Lactobacillus plantarum were screened from traditional fermented food in northeast China,including capsicum sauce,stinky tofu and sticky face. 75 strains of Lactobacillus plantarum were divided into acellular supernatant,intact cell and acellular extract three components. The DPPH and ABTS⁺ free radical scavenging rate were used to screen the strains,and the correlation between different indicators was analyzed. The acid and bile salt tolerance of the strain and its sensitivity to antibiotics were evaluated. The results showed that 23 strains showed good antioxidant activity. The scavenging rates of DPPH and ABTS⁺ free radicals in acellular supernatant were more than 90%,and those of intact cells and acellular extracts were more than 30%. The three components of Lactobacillus plantarum were correlated in scavenging DPPH free radicals,while the cell-free supernatant was significantly correlated in DPPH and ABTS⁺ evaluation methods. Among them,5 strains of Lactobacillus plantarum(D2,H8,L20,L11 and A2)survived more than 59% at pH2.0 and 93% in 0.3% bile salt. They were highly sensitive to 7 antibiotics. Therefore,these five strains of Lactobacillus plantarum would have potential application value in the development of functional food with antioxidant activity.