Identification of bacterial species from raw milk by 16S r DNA sequencing

Using glass bead method to extract the genomic DNA of 34 bacterial strains which were isolated and purified in raw milk.Common primer 27 f /1492 r was used to amplify 16 S r DNA fragments. The PCR products were sequenced.Then the 16 S rRNA sequences were compared with Gen Bank database homologous sequence and the phylogenetic tree was constructed through clustering analysis. The phylogenetic status of 34 species of bacteria were determined combined with morphological and physiological characteristics.The results showed that 16 kinds of species were identified.Bacterial species and its distribution characteristics were different among three raw milk samples,where the 1st sample had 7 kinds of bacteria,mainly Acinetobacter sp; the 2nd sample had 6 species,mostly Klebsiella sp.; the 3rd sample had 6 species of bacteria,the distribution was more dispersed. From the pathogenic point of view,all strains were opportunistic pathogens or spoilage,no virulent pathogens.