Abstract:In order to obtain cellulose-degrading probiotics from Tibetan sheep, cellulose Congo red medium was used to isolate and screen cellulose-degrading bacteria from the rumen fluid of Tibetan sheep Species identification was performed through combining morphological examination, physiological and biochemical identification, and 16 S rDNA sequence analysis. Some biological characteristics of the isolated strain were studied through the determination of growth curve, antibacterial test and drug susceptibility testing. The results showed that a pink and Gram-positive strain was screened out on cellulose Congo red medium (named BS1-ql). The isolated strain, BS1-ql, produced spores, and its physiological and biochemical characteristics were in line with the characteristics of Bacillus genus, such as positive oxidase test and catalase test. Its 16S rDNA sequence was more than 96% similar to that of multiple Bacillus strains, 100% homologous to Bacillus safensis and in the same smallest branch. It was confirmed that the isolated strain was Bacillus safensis. BS1-ql grew rapidly and entered the logarithmic phase 2 h after inoculation; the inhibition zones against Escherichia coli, Salmonella, Staphylococcus aureus and Clostridium perfringens were all above than 8.96 nm, indicating a certain degree of inhibition; BS1-ql was sensitive to most commonly used antibiotics to varying degrees, and resistant to ceftazidime antibiotics. Conclusion: A strain of Bacillus safensis from Tibetan sheep was successfully isolated and identified. The isolated strain has good biological characteristics and can be a candidate strain for probiotics from Tibetan sheep.
