Isolation and Identification of Potential Bacillus Probiotics from Free Ranging Yaks of Tibetan Plateau, China

The present study was planned to isolate and identify the Bacillus probiotics from free ranging yaks of Tibet in order to prevent the epidemic calf diseases through beneficial strains. For this purpose, three Bacillus subtilis strains (named BS1, BS2, and BS3) and one Bacillus velezensis strain (named BV1) were isolated from the intestinal contents of Tibetan yaks. Meanwhile, Staphylococcus aureus (S. aureus ATCC 26112), Escherichia coli (E. coli ATCC 25922) and Salmonella enteritidis (S. enteritidis NCTC 13349) were used as reference strains to test the antibacterial activity of the isolates. All the strains had strongest bacteriostatic ability against the reference strains with perfect bile and acid tolerance, especially BV1 exhibiting the highest antibacterial activity. In addition, antibiotic resistance, resistance gene, oral testing and hemolytic analysis were also performed to confirm the safety of these isolates. Furthermore, experimental group showed a better growth trend as compared to the control group. In conclusion, in present study four isolated strains of Bacillus prove to be safe, possess growth promoting activity and promote the healthy balance of gut microflora. (C) 2018 PVJ. All rights reserved