Studies On The Biological Properties And Identification Of Lactobacillus Plantarum

10 strains were isolated from the excrements of infants and cows in Huhhot ,and the endurances of 10 strains to12 kinds of antibiotics have been tested and the capability to produce vitamin B6 were screened. The results showed that 4 of them had a higher capability to produce Vitamin B6, they are B25, B72, B76 and N59-1. Meanwhile, the 4 strains were also tested by acid and bile tolerance. The results indicated that the 4 strains had different capabilities to tolerate acid and bile, the one with N59-1 had higher capability of acid and bile tolerance than others. And in the endurance tests of artificial gastric juice and artificial intestinal juice, the N59-1 had a survival rate of 89.33% by keeping in the artificial gastric juice for 3h, then it was transferred into artificial intestinal juice and kept for other 3h,its survival rate was still larger than 80%, while the survival rates of other 3 trains were all less than 80%.the N59-1 had a certain number of survival strains until 24h,the survival rate was 77.20% and logarithmic value of survival strains number was 7.45.Based on the traditional bio-chemistry identification, the strain of N59-1 was tested by gene amplification and the gene sequence was measured by taking use of molecular biology method, the result were analyzed by comparing with the 16S rRNA/DNA gene sequence of the standard strains of lactobacillus. Then a phylogenetic dendrogragm was constructed. The results indicted that the homology of N59-1 with L.plantarum JCM1149 was 99.7%. Combining with analysis of the phylogenetic dendrogragm and partial sequences of 16S rDNA , N59-1 was classified as L.plantarum. The result was coincided with that of traditional classification before. In toxicity test, L.plantarum N59-1 was lavaged into Mus musculus albus, the results showed that N59-1 was safe. Culture medium for L.plantarum N59-1 were optimized by orthogonal experiment design, the results indicated that 8 hours was the terminal time, at this time L.plantarum N59-1 got to 7.0â…¹1010cfu/ml . Compared with ordinary MRS liquid culture medium, the optimized culture medium for N59-1 had a significant effect of bacteria increment.