Isolation And Identification Of The Lactic Acid Bacteria From The Natural Fermented Sausages

There are rich strains resources exist in the local natural fermented sausage, which collect from Chengdu, Leshan, Chongqing, Shandong, Hubei and other 20 citys. Strains were isolated and Purified from the 20 samples of natural Fermented sausages.The selected strains have excellent fermentation characteristics,and identified it to Species. Discuss the Mechanism of its antimicrobial activity. Finally, let benefit nature as an index and established a more comprehensive screening system for bacteria fermented sausages.The contents include the following sections:Purified from the sample, produce 45 strains of dissolved calcium circle, Observe the morphological characteristics, there are 37 strains of Bacillus,8 strains of Cocci.According to the pH declines, nitrate tolerance and salt tolerance screened out the bacteria which meet with basic conditions for the fermented sausage,26 strains satisfy the condition.Made molecular extraction for the 26 selected strains, ERIC-PCR cluster. Separate 4 major categories, representing the molecular identification of strains, there are the Lactobacillus plantarum, Lactobacillus farciminis, Lactobacillus curvatus and Lactobacillus casei.Made physiological characteristics research on the selected representative strains of each type. temperature value was30℃, initial pH value was 6.5, static culture. Growth curves of the lactic acid bacteria was determined. Identified 16h to 20h was the best time for fermentation harvest, when the biomass accumulation up to maximum.24-hour production of pH curves are almost the same with growth curve.According to the Fermentation characteristics, selected 13 strains of bacteria,they did not produce slime and H2O2,CO2 from glucose,H2S,NH3 from arginine.they did not have proteinase and lipase activity.they also had no decarboxylase activity.Cwl and Cq4 displayed nitrate reduction.Selected strains with antimicrobial activity, Get 12 strains bacteria which have antibacterial activity to 1 or more than 2 indicator bacteria. Explore the inhibitory mechanism. investigate the antibacterial mechanism, antimicrobial test 13 strains,in addition to 9 strains which because antimicrobial acid and other factors, the remaining four are bacteriocin producing strains of bacteria, the proportion reached to 31%.Choose the strains which have degradation of cholesterol more than 20%, there are total of S12, Cq3, Dz1, Cw1 and Sl1 five strains, Sl2 have the strongest cholesterol degradation,the degradation rate reached 25% after 72h.and finally coupled with Cq4 which have nitrate reduction capacity, finally get six strains which consistent with the production of sausages fermentation agent.According to their Antagonistic test, there was no antagonism,selected fermentation agent can be used for industrial production.