Isolation And Characteristic Of Weissella In Natural Fermentation Jinzhou Side Dishes

The natural fermented Jinzhou side dishes are fresh vegetables as raw material,added to rich sauce with lactic acid bacteria under natural conditions.The Jinzhou side dishes is one of the featured pickle food in Liaoning Province.It has a great variety of flavors,good taste and safety quality,so that loved by local people.The natural fermented Jinzhou side dishes have rich lactic acid bacteria resources.The microbial diversity analysis shows that it rich in Lactobacillus plantarum,Weissella sp.,Entrococcus faecium,Lactobacillus lactic and so on.In this study,we isolated Weissella from the natural fermented Jinzhou side dishes by 16S rDNA sequence homology analysis.Futher optiminze the composition of medium for the growth of Weissella,which meets the nutrition requirment and well grow and multiply of Weissella.Finally,we analyze the characteristic of Weissella.For examples:acid resistant,salt tolerant,product aicd ability,antibacterial ability,nitrie-reducing ability,sticky ability,resistance to bile salts ability.It is laid foundation for the application of Weissella in fermented food.Test 1:In this experiment,120 strains of lactic acid bacteria were isolated from 27naturally fermented Jinzhou side dishes by separation and purification techniques.After morphological observation,90 strains of lactic acid bacteria were found to be irregular,short rod-shaped,with round or slightly rounded ends,pairs or short chains.The 48 strains of suspected Weissella species were identified by physiological and biochemical tests.Using16SrDNA sequence homology analysis,the results showed that DRF1-9,DRF1-10,CS2-2,HL2-3,JL3-4,and ZS2-2 were all belonged to Weissella.DRF1-9,DRF1-10 and JL3-4 are all Weissella viridescens,CS2-2,HL2-3 and ZS2-2 are all Weissella minor.Test 2:The single factor test and orthogonal experiments using different carbon sources,nitrogen sources,and nutritional factors.We determined the strains of W.viridescens DRF1-9and W.minor HL2-3.The most suitable carbon source was glucose+sucrose?1:2?5%?v/v?for the expansion of fermentation,and the nitrogen source was peptone+beef extract+yeast extract 0.8%?v/v?and tomato juice was 5%?v/v?.The orthogonal experiments showed that the nitrogen source was the main factor affecting the growth of Weissella,followed by the carbon source and growth factor.Test 3:W.viridescens DRF1-9 and W.minor HL2-3 had the highest OD₆₀₀00 value and the highest salt tolerance at NaCl concentration of 2%?v/v?.With the decrease of pH value,Weissella is inhibited significantly.With the extend of fermentation time,the degradation rate of nitrite is gradually increased in Weissella,and the rate of maximum degradation reached98-99%in the range of 16-18h.The viscosity of fermented milk gradually increased at 0-18h and the viscosity began to decrease at 18-24h.The pH value much drops at 3-12h.The bile salt concentration of 0.1g/L,which the survival rate is the strongest,98%and 95%respectively.With the bile salt concentration increased,the survival rate began to decline.The antibacterial activity of W.viridescens DRF1-9 and W.minor HL2-3 against Escherichia coli882364,Staphylococcus aureus AS1.2465,Listeria monocytogenes C53-3.The antibacterial activity against Escherichia coli 882364 was the strongest and the diameter of inhibition zone was 11.15±0.28mm and 12.56±0.33mm?...