In this study, a bacterial strain COFCAU_P1, isolated from the digestive tract of a freshwater teleost rohu (Labeo rohita), was identified as Bacillus amyloliquefaciens using 16S rRNA gene sequence analysis combined with amplification of species-specific BamHI and barnase genes. The probiotic potential of the strain was evaluated using an array of in vitro tests along with safety and genetic analyses. The isolate showed potent antimicrobial response against several fish pathogenic bacteria, survived a wide pH range (2–9), and was resistant up to 10% bile salt concentration. With regard to the in vitro adhesion properties, the strain showed significantly high in vitro adhesion to mucus, auto and co-aggregation capacity, and cell surface hydrophobicity. The strain was non-haemolytic, able to produce extracellular enzymes, viz., proteinase, amylase, lipase, and cellulase, and showed significant free radical scavenging activity. A challenge study in rohu revealed the strain COFCAU_P1 as non-pathogenic. The presence of putative probiotic marker genes including 2, 3-bisphosphoglycerate-independent phosphoglycerate mutase, arginine/ornithine antiporter ArcD, choloylglycine hydrolase, LuxS, and E1 β-subunit of the pyruvate dehydrogenase complex was confirmed by PCR, suggesting the molecular basis of the probiotic-specific functional attributes of the isolate. In conclusion, the in vitro and genetic approaches enabled the identification of a potential probiotic from autochthonous source with a potential of its utilization in the aquaculture industry.

本研究采用16S rRNA基因序列分析结合物种特异性Bam扩增，从淡水硬骨鱼( Labeo rohita )消化道中分离出一株COFCAU_P1菌株，鉴定为解淀粉芽孢杆菌。HI和barnase基因。使用一系列体外测试以及安全性和遗传分析来评估菌株的益生菌潜力。该分离物对几种鱼类病原菌表现出有效的抗菌反应，在较宽的 pH 值范围 (2-9) 中存活，并且对高达 10% 的胆盐浓度具有抗性。关于体外粘附特性，该菌株对粘液的体外粘附、自聚集和共聚集能力以及细胞表面疏水性显着提高。该菌株是非溶血性的，能够产生细胞外酶，即蛋白酶、淀粉酶、脂肪酶和纤维素酶，并显示出显着的自由基清除活性。在 rohu 进行的一项挑战研究表明，COFCAU_P1 菌株是非致病性的。存在推定的益生菌标记基因，包括 2、通过 PCR 证实了丙酮酸脱氢酶复合物的LuxS和 E1 β-亚基，表明分离物的益生菌特异性功能属性的分子基础。总之，体外和遗传方法能够从本土来源中鉴定出一种潜在的益生菌，并具有在水产养殖业中使用的潜力。