新疆牛源地衣芽孢杆菌NXJ-1的分离鉴定及益生特性与安全性评价OA

This study aimed to screen probiotic Bacillus strains with potential for feed development indigenous to Xinjiang.Fresh feces from healthy Holstein dairy cattle in Shihezi,Xinjiang were used as samples.Spore-forming bacteria were enriched by heat treatment,followed by isolation and purification.Strain identification was accomplished through morphological observation and 16S rRNA gene sequencing.The probiotic properties and biosafety of the strain were systematically evaluated.The results showed that one strain of Bacillus licheniformis NXJ-1 was isolated,exhibiting γ-hemolysis.It demonstrated excellent growth performance,entering the logarithmic growth phase two hours after inoculation,with an optimal growth pH of 6.0.After three hours of incubation in simulated gastric fluid and intestinal fluid,the viable cell survival rates reached 72.00%and 84.10%,respectively.The 24-hour auto-aggregation rate was 40.12%.Preliminary antibiotic susceptibility screening revealed that the strain exhibited varying degrees of inhibitory response to 20 commonly used veterinary antibiotics,with inhibition zone diameters＞20.0 mm for 16 antibiotics,and no significant drug resistance phenotype was observed.Mouse safety tests confirmed that mice in all dosage groups showed no abnormalities,and the strain had no adverse effects on mice growth performance.Notably,the total serum protein content in the medium-dose group was extremely increased(P＜0.01),with no significant effects on core indicators of kidney function.The study shows that Bacillus licheniformis NXJ-1 possesses excellent probiotic properties and reliable biosafety,demonstrating good potential for forage development,which may provide a reference for antibiotic alternatives in indigenous ruminant farming in Xinjiang.