关键词: 牛链球菌; 分离鉴定; 16S rDNA; 生物信息学

Abstract: In this study,the dung samples of a sick cattle from an animal hospital were detected by bacteria cultivation.The bacteria were cultured by different differential media,and analyzed by biochemical test,16S rDNA gene was amplified by PCR,then sequenced and constructed phylogenetic tree,drug sensitivity test and growth curve were carried out.The results showed that the bacteria could grow smooth bulge,rounded edges,different size,different colors of the bacterial colonies in blood agar,chocolate agar,LB agar and so on,but could not grow in MRS agar and high salt mannitol agar.The results of lactose,maltose,mannitol and so on were negative,the results of glucose,simmon's citrate and urea were positive,this bacteria were identified as Streptococcus bovis by these preliminary results,and confirmed by phylogenetic tree construction.This isolate exhibited 99% nucleotide sequence identity with Streptococcus bovis RD09.The drug sensitivity test result of Streptococcus bovis showed that it was extremely sensitive to doxycycline and kanamycin,highly sensitive to erythromycin,sensitive to streptomycin,novobiocin,cotrimoxazole,ceftriaxone and gentamycin,resistant to chloramphenicol,cephalosporins cefradine and amoxicillin.The growth curve of Streptococcus bovis indicated that a rapid growth phase of the bacteria was from 2 to 23 h,the stationary phase was from 23 to 28 h,the decline phase was after 28 h.These experimental data provided the prerequisite for further study of Streptococcus bovis.

Key words: Streptococcus bovis; isolation and identification; 16S rDNA; bioinformatics