Isolation,Identification and Safety Evaluation of a Sheep-Derived Bacillus megaterium BM24
The aim of this study was to evaluate the in vitro probiotic potential and in vivo safety of a strain of Bacillus megaterium BM24 isolated from the feces of healthy fine wool sheep.Collection of fresh faeces from healthy,antibiotic-free Xinjiang fine-haired sheep.The Bacillus strain was initially obtained by morphological i-dentification,biochemical identification and 16S rRNA sequencing.Subsequently,through the detection of Ba-cillus-tolerance to the environments of acidic and high bile salt concentrations,in vitro antibacterial ability,drug resistance,hemolytic activity and growth curve of the strain,the isolated Bacillus strain was eventually judged to have in vitro safety.Finally,the safety of the isolated Bacillus strain was evaluated by in vivo test in mice.The results showed that:1)a Bacillus strain was preliminarily isolated and named Bacillus megaterium BM24 according to the results of biochemical identification and 16S rRNA sequencing.2)Bacillus megaterium BM24 could survive at pH=1.0,with a survival rate of 49％after 4 h of incubation with 0.3％bile salt.Bacil-lus megaterium BM24 was highly sensitive to 12 of 15 common antibiotics,had good inhibitory effect on com-mon diarrhea pathogens Salmonella and Escherichia coli,and had no hemolytic activity.3)The growth entered the logarithmic phase after 2 h at 37 ℃,after 6 h,the growth reached a plateau.4)No death,normal body weight change,and no pathological changes in organs in the body cavity of mice when the Bacillus megaterium BM24 treated by gavage.There were no significant effects on the liver,kidney,spleen,organ indexes and blood cell indexes(P＞0.05);no death,normal vital signs and no pathological changes in the organs in body cavity of mice at the Bacillus megaterium BM24 treated by intraperitoneal injection.In summary,the sheep-de-rived Bacillus megaterium BM24 isolated in this experiment has terrific in vitro probiotic potential without acute toxic effect,which can be used as a candidate strain of sheep probiotics.[Chinese Journal of Animal Nutri-tion,2024,36(9):6083-6094]
Bacillus megateriumprobioticfine wool sheepisolation and identificationsafety
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