Production Of Lactic Acid Bacteria Bacteriocinand Its Application On Fish Preservation

Lactobacillus bacteriocin is a kind of protein or polypeptide substance which has effects of sterilization or antibacterial,they are produced by the lactic acid bacteria in the metabolic process used DNA as a template,and then compiled by transcription and translation.Because of its sensitivity to some proteases,Because of its sensitivity to certain proteases,Bacteriocin can be digested in the gastrointestinal tract,So the safety of bacteriocin is very high.Lactobacillus is also a globally recognized safe strain,So lactic acid bacteria bacteriocins were used in the food industry and feed industry and so on,it is significantfor the protection of food safety.The paper was based on the identification of the two bacteriocin-producing lactic acid bacteria(Lactobacillus plantarum 163 and Lactobacillus acidophilus NX2-6)and identification of the bacteriostatic structure of the two strains in our laboratory.In this paper,two medium-lactic acid bacteria-producing medium and fermentation conditions were optimized by response surface methodology.And the fermentation broth of Lactobacillus plantarum with high antibacterial activity was selected and sprayed to prepare antibacterial substance with antibacterial activity and the product was applied to the preservation of grass carp fillet.The aim of this study is to provide technical support for the application of lactic acid bacteria bacteriocin.The main research results are as follows:1.Optimization of Lactobacillus acidophilus NX2-6fermentation.The optimum medium was as follows:skim milk powder 53 g/L,corn flour 20 g/L,sodium acetate 10 g/L,diammonium citrate 6 g/L,fermentation conditions:initial pH 5.7 And inoculation amount was 9%(v/v).Compared with the original MRS medium,the diameter of the inhibition zone increased from 17.23 mm to 26.79 mm.The diameter of the inhibition zone increased to 1.6 times the original.2.Lactobacillus plantarum 163 fermentation optimization.Production conditions of Lactobacillus plant.The final fermentation medium ofLactobacllus plantarum 63obtained by the single-factor experiment,Plackett-Btmnan design and Box-Behnken design was:maltose syrup 55 g/L,corn steep powder 20 g/L,sodium acetate 8 g/L,Citric acid diammonium citrate 6g/L,Tween-80 1.26 g/L,fermentation conditions:initial pH 4.7,inoculation amount was 2%(v/v).The diameter of the final inhibition zone increased to 31.90 mm,which was 1.1 times higher than that of the original MRS medium.Study on the Properties of Lactobacillus plantarum 163 Spray Drying Products.Lactobacillus plantarum 163 products on Gram-positive,Gram-negative bacteria have antibacterial activity,no fungal antibacterial activity.Lactobacillus plantarum 163 product thermal stability is good,can be applied in a wide temperature range.The antibacterial activity of Lactobacillus plantarum 163 showed a higher bacteriostatic activity with pH,which showed higher bacteriostatic activity at low pH,and the antibacterial activity between pH 4.5 and pH 6.5 was stable.Study on Fresh-keeping Effect of Fish.Fish as a perishable food,which is the need for safe and efficient preservative,lactic acid bacteria as a recognized safety strains,the production of antimicrobial substances to meet the fish meat preservation needs.In this experiment,Lactobacillus plantarum 163 was selected as the strain.After fermentation through the modified medium,the fermentation supernatant was spray dried to obtain the antibacterial substance,which was applied to the preservation and preservation of the grass carp fillet.The results showed that the preservation effect of 2%Lactobacillus plantarum inhibitory solution was similar to that of 0.5%Nisin solution,and the results showed that the freshness of the solution was similar to that of 0.5%Nisin solution.Can inhibit the microbial,chermical and its sensory changes,4%Lactobacillus plantarum inhibitory effect of preservation is better than other groups,the best preservation effect.