Isolation, Identification And Application Of Dominant Microorganisms In Preserved Mud Snail

The safety of food is related to people’s health.Therefore,it is of vital importance to clarify the microflora structure in preserved conch to optimize its traditional processing technology and improve the nutrition and flavor.In this study,22 culturable strains were isolated from five groups of preserved mud snails.The dominant bacteria of sample 1 were Staphylococcus xylosus,Bacillus cereus and Bacillus subtilis.The dominant bacteria in sample 2 was Bacillus kochii.The dominant bacteria in sample 3 was Bacillus licheniformis.One Bacillus megaterium strain was isolated from sample 4.There is not dominant bacteria ins sample 5 to be isolated.Compared with other biological preservatives,lactobacillus and its metabolites were a new way of biological preservatives due to the advantages of higher safety,no residue and broad antimicrobial spectrum.The preservative function of lactic acid bacteria has been applied in dairy products,meat products,fruits and vegetables,aquatic products,etc.The count of lactic acid bacteria(MRS)of samples 1,2,4 and 5 was between 10-100 CFU/g.The sample 3 is less than 10CFU/g,no lactic acid bacteria growth.A single colony of lactic acid bacteria was picked from counting tablet,mixed with30% glycerol ion,and stored at-70 ℃ refrigerator freezer.Three strains of lactic acid bacteria were selected and measured their properties of salt tolerance,acid production and bacteria inhibition.The results indicated that three selected lactobacillus strains showed good growth performance,which fully demonstrated that the three strains had good tolerance to salt.However,the growth of the three strains was significantly inhibited with the increase of salt concentration.The present results indicated that the lactobacillus involved in the experiment can rapidly proliferate and accumulate metabolites of organic acid.In addition,the bacteriostatic test results of three strains of lactic acid bacteria showed that L1 had no obvious inhibiting effect on Escherichia coli,Staphylococcus aureus and salmonella,while L2 and L3 had bacteriostatic effect on the three tested strains,while L3 had more bacteriostatic effect on salmonella than L2.Lipase and protease produced by Staphylococcus xylosus can decompose proteins,peptides and fat to form esters and volatile flavor substances in meat products and play an important role in the formation of flavor and enhance the taste of food products.Staphylococcus xylosus has the characteristics of adapting to the environment of fermentation and high salinity in the process of food production.In this study,the nitrite resistance of Staphylococcus xylosus was tested.The growth curve showed that four strains of Staphylococcus xylosus could directly enter the logarithmic growth period,reach the growth peak after growing for 18 h,and then keep stable.When the concentration of nitrite was less than 30mg/kg,the growth performance of Staphylococcus xylosus was better.However,the growth of the strain was seriously inhibited when the nitrite concentration was greater than 50mg/kg.In addition,S1 and S2 had better resistance to nitrite compared with the four strains.In this study,the dominant microorganisms in traditional preserved mud snail from wenzhou were isolated and identified for screening out the best strains or their combinations suitable for industrial production.The results indicated that the isolated strains can be used to marinate mud snail with good flavor and strong nutritional function through changing the traditional marinating technology of high salt and high alcohol.