Screening,Identification And Characterization Of Lactic Acid Bacteria With Potential Probiotics

In order to obtain lactic acid bacteria(LAB)strains with potential probiotic characteristics and to provide strains for future development of probiotic products.LAB strains were isolated,identified and characterized by plate streak method from pork,sauerkraut,micro bran,Daqu,balsamic vinegar,curd,yoghurt and yoghurt samples.Antioxidant activity,antibacterial activity and growth characteristics were also examined.The result are as follows:A total of 211 strains of lactic acid bacteria were isolated and purified from 13 samples,including 146 strains of Lactococcus and 65 Lactobacilli.Screened with pH 3.0 and 0.3% bile salts,67 strains of lactic acid bacteria could grow under this condition.8 strains of lactic acid bacteria could grew under pH 2.5 even pH 2.0,7 strains were well tolerated through simulated gastric fluid and simulated intestinal fluid,which named as DQ12,FQ7,H2,XC2,XC4,ZR11 and ZR21.Through the tests of surface hydrophobic,antioxidant ability and antimicrobial ability,7 strains mentioned above all have preferably antioxidant and antimicrobial ability.Combined with morphological identification,physiologicalbiochemical identification and 16 S rRNA gene sequence analysis,concluded that DQ12,H2,XC2,ZR11 were Pediococcus acidiacidis,FQ7,XC4,and ZR21 was Pediococcus pentosaceus.7 strains with potential probiotics were researched through growth characteristics.The logarithmic phase of DQ12,FQ7,XC2 and ZR11 were from 2 to 8 h.H2,XC4 and ZR21 were from 2 to 6 h.All 7 strains could grew in MRS medium with initial pH from 3.0 to 9.0.And all 7 strains can live and grow in a medium with the concentration of NaCl is either at 2%,4% or 6%.Besides,FQ7,XC4 and ZR21,these three strains have good tolerance of 8% concentration of NaCl.