Analysis of Bacteriostatic Characteristics of Lactic Acid Bacteria Isolated from Fermented Meat

In order to screen lactic acid bacteria with inhibitory activity and analyze the inhibitory substance basis,the inhibitory ability of fermentation supernatant from 19 lactic acid bacteria,isolated from air dried meat products in pastoral areas,to E. coli and S. aureus were analyzed by Oxford cup agar diffusion method.Finally three of them with significant difference in inhibitory ability of E. coli and S. aureus were selected respectively to analyze the inhibitory substance basis and influence factors of inhibitory ability in its fermentation supernatant. The result showed that F19 strain had the strongest inhibitory activity to E. coli,and the diameter of the inhibitory circle was(15.07±0.55) mm,while the fermentation supernatant of F11 had no inhibitory effect on E. coli at all. The F16 had the strongest inhibitory activity to S. aureus,and the inhibitory circle diameter was(14.47±0.38) mm,while the fermentation supernatant of F6 and F2 had no inhibitory effect on S. aureus at all. According to the analysis of the inhibitory substance basis,acidic environment played a leading role in the process of bacteriostasis. Bacteriocins and hydrogen peroxide had a synergistic effect. The fermentation supernatant of the test strains was treated with different pH and temperature,and it was found that the inhibitory activity of the fermentation supernatant was significantly enhanced with the decreasing of pH when pH<5.0(P<0.05). When the pH value increased to 5.0,6.0 and 7.0,the experimental lactic acid bacteria fermentation supernatant had no inhibitory ability. After heat treatment at 60,80,100 and 121 ℃ for a certain time respectively,the inhibitory ability of F18 fermentation supernatant was still not significantly different from that of the control group(P>0.05).After heat treatment at 100 ℃ for 30 min,the inhibitory activity of the fermentation supernatant of F11 significantly decreased(P<0.05). When the treatment temperature of the fermentation supernatant of other experimental strains reached above 60 ℃,the inhibitory activity significantly decreased with the increase of heat treatment temperature(P<0.05). In conclusion,lactic acid bacteria fermentation supernatant had specific inhibitory effect,and the main bacteriostatic substances were acid substances,followed by bacteriocin and hydrogen peroxide.The bacteriostatic ability was affected by pH and temperature with specificity,which could provide theoretical guidance and technical support for the development of high quality strain resources.