Table_1_Characterization and Functional Test of Canine Probiotics.DOCX

Probiotics can modulate the composition of gut microbiota and benefit the host animal health in multiple ways. Lactic acid bacteria (LAB), mainly Lactobacillus and Bifidobacterium species, are well-known microbes with probiotic potential. In the present study, 88 microbial strains were isolated from canine feces and annotated. Among these, the four strains CACC517, 537, 558, and 566 were tested for probiotic characteristics, and their beneficial effects on hosts were evaluated both in vitro and in vivo; these strains exhibited antibiosis, antibiotic activity, acid and bile tolerance, and relative cell adhesion to the HT-29 monolayer cell line. Byproducts of these strains increased the viability and decreased oxidative stress in mouse and dog cell lines (RAW264.7 and DH82, respectively). Subsequently, when the probiotics were applied to the clinical trial, changes in microbial composition and relative abundance of bacterial strains were clearly observed in the experimental animals. Experimental groups before and after the application were obviously separated from PCA analysis of clinical results. Conclusively, these results could provide comprehensive understanding of the effects of probiotic strains (CACC517, 537, 558, and 566) and their industrial applications.

益生菌可调控肠道菌群（gut microbiota）组成，并通过多种途径改善宿主动物的健康状况。乳酸菌（Lactic acid bacteria, LAB）主要涵盖乳杆菌属（Lactobacillus）与双歧杆菌属（Bifidobacterium）物种，是一类公认的具备益生菌潜力的微生物。本研究从犬粪便中分离并注释了88株微生物，其中4株菌株CACC517、537、558及566被开展益生菌特性检测，并通过体外（in vitro）与体内（in vivo）实验评估其对宿主的有益效应；结果显示，这些菌株具有抗生作用（antibiosis）、抗生素活性（antibiotic activity）、耐酸耐胆盐能力，以及对HT-29单层细胞系的相对黏附能力。该4株菌株的代谢产物可提升小鼠RAW264.7细胞与犬DH82细胞的存活率，并降低其氧化应激（oxidative stress）水平。随后将该益生菌应用于临床试验（clinical trial），实验动物的菌群组成与菌株相对丰度均出现显著变化；临床样本的主成分分析（Principal Component Analysis, PCA）结果显示，给药前后的实验组可被明显区分。综上，本研究结果可为CACC517、537、558及566这4株益生菌菌株的作用效应与工业应用提供全面的理论参考。