副干酪乳酪杆菌CD12-1的筛选、益生特性及基因组安全性评价OA

Traditional fermented dairy products are important sources of lactic acid bacteria(LAB).To screen LAB with probiotic po-tential from the Qinghai-Tibet Plateau,101 candidate strains were isolated from traditional fermented yak milk in Xinjiang and Tibet.Strain characteristics were systematically evaluated,including acid tolerance,bile salt tolerance,simulated gastrointestinal fluid tolerance,auto-aggregation,surface hydrophobicity,and antioxidant activity.Safety testing and whole-genome sequencing(WGS)were also conducted on the screened strains.The results showed that the strain CD12-1 exhibited the best overall performance,with acid and bile salt tolerance rates of 73.34％and 37.43％,respectively.Survival rates in simulated gastric and intestinal fluids were 121.63％and 76.57％.Auto-ag-gregation and surface hydrophobicity reached 91.19％and 82.97％,and DPPH radical scavenging activity was 72.17％.The strain was sensitive to antibiotics such as erythromycin,penicillin,and cefazolin,and showed no hemolytic activity.Based on 16S rRNA gene se-quence analysis,this strain was identified as Lacticaseibacillus paracasei.Whole-genome sequencing results revealed that its genome length was 2 483 754 bp with a GC content of 46.5％,containing 2 844 protein-coding genes.Functional annotation indicated that the strain's genome was rich in genes related to acid resistance,adhesion,transport,bacteriocins,and cold/heat shock proteins,and no risk genetic elements with horizontal transfer potential were detected.In conclusion,CD 12-1 shows strong probiotic potential and high safety,and its genomic features support its potential application use as a probiotic.