Isolation, Identification and Drug Susceptibility Test of Enterococcus faecalis from Tibetan Sheep of Euler Type

Enterococcus faecalis was isolated from intestinal contents of healthy Euler Tibetan sheep and preliminarily identified, in order to screen out strains with excellent probiotic characteristics and study their growth characteristics. In this paper, the isolated strain EF1-mh was separated and purified, examined by gram staining microscopy, biochemical test, 16S rDNA sequencing test, growth curve test, acid-producing ability test, drug sensitivity test and bacteriostatic test. The results showed that the isolated strain EF1-mh was a gram-positive cocci without spores and sterile hairs. Biochemical test showed that the isolated strain EF1-mh could decompose maltose, glucose, fructose, etc., but it could not decompose mannitol, sorbitol, raffinose, L-rhamnose, arabinose, and had the activity of L-arginine double hydrolase. The results of bile esculin agar indicator were black and did not produce hydrogen sulfide. Indole test and VP test were negative. Nitrate could not be reduced without Simone citrate and gluconate as energy sources. 16S rDNA sequencing identified the isolated strain EF1-mh as E. faecalis. The results of growth curve measurement and acid-producing ability showed that EF1-mh strain had strong growth ability and weak acid-producing ability. The results of drug sensitivity test showed that EF1-mh strain showed moderate sensitivity to oxacillin, cefuroxime, cefalexin, cefradine, doxycycline and minocycline. They were resistant to furazolidone, sulfamethoxazole, ceftazidime and polymyxin B. Bacteriostatic test results showed that the supernatant of EF1-mh strain could effectively inhibit the growth of common pathogenic bacteria, and had a good bacteriostatic effect on four common pathogenic bacteria such as Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Clostridium perfringens. Among them, it had the strongest bacteriostatic ability against Clostridium perfringens. The results would provide basic candidate strains for further exploration of microecological agents from Tibetan sheep.