Screening Of Bacteriocin-producing Lactic Acid Bacteria, Optimization Of Culture Conditions And Study Of Biological Characteristics

Lactic acid bacteria is closed to human life such as using them to protect food. With the further study on its mechanism of inhibition, we found that the main factors were the antibacterial substance produced in the fermentation process such as organic acid, hydrogen peroxide and bacteriocins. With a daily increase of antibiotic resistance problems and hazards of chemical preservatives and other issues prompted people looking for a no side effects, non-toxic, no resistance, no residue, and can kill or inhibit many pathogens and corruption bacteria, can replace chemical preservatives and antibiotics natural antibacterial products. The lactic acid bacteria known for its natural characteristics inevitable in the future for human health and make a great contribution.The original strain L1 was screened out by the predecessors. The following researches were carried out.Firstly, The three rounds of UV-Microwave-UV mutagenesis methods were carried on L1 with blank control groups. Calculated the disability rate and chose the best mutagenic dose. The selected strains were brought into the next link. The results showed that the growth capacity and antibacterial properties of L1-UVs3 were both improved.Effects of different types and concentrations of carbon, nitrogen, stimulating factor and metal ions on bacteriocin production. By single factor and orthogonal test, optimum parameters of the medium, namely glucose concentration of 2.5%, 2.0% peptone, sodium chloride concentration of 0.20% Tween 80 concentration of 0.2%, 37 ? for 24 hours, the ratio antibacterial diameter strain culture medium under L1-UVs3 bacteriocins produced maximum yield up to bacteriocins, antimicrobial experimental determination of inhibition zone diameter of 16.87 mm.In this paper, the biological characteristics of lactic acid bacteria prime preliminary study, based on the current results, we draw the following conclusions: lactic acid produced bacteriocin has good thermal stability, 121? 30 min remain after heat treatment have partially active L1-UVs3; the bacteriocin under acidic and neutral conditions still has antibacterial vitality, significantly reduce bacterial viability under alkaline conditions. The bacteriocin pepsin, trypsin, proteinase K, papain sensitive; frozen, chilled bacteriocins still has a good antibacterial activity. Results and fermentation broth additive interaction showed supernatant sodium saccharin, almost no differences were D- sodium erythorbate and sodium tripolyphosphate interaction with the control group inhibitory effects of vitamin C on antimicrobial bacteriocins activity has improved to some extent, promote the inhibitory effect of sodium citrate on the more obvious, add a solution of potassium sorbate maximum inhibition zone diameter. G+ and G- pathogenic bacteria have good antibacterial effect. Crude bacteriocins extract cell-free supernatant than the antibacterial activity of large.This study screened out a high yield of lactic acid bacteria prime determine the optimal conditions for lactic acid bacteria prime medium parameters, conducted a preliminary inquiry of its biological stability of the fermentation broth is provided for the promotion and application of bacteriocins basic data and theoretical support.