乌鳢肠道芽孢杆菌的分离鉴定及益生特性评估

ISOLATION, IDENTIFICATION, AND EVALUATION OF BACILLUS PROPERTIES OF INTESTINAL BACILLUS FROM CHANNA ARGUS

  • 摘要: 分离鉴定乌鳢(Channa argus)肠道芽孢杆菌, 评估分离菌用作饲料添加剂的益生潜力。收集乌鳢肠道样本, 研究采用稀释涂布法分离细菌, 经16S rRNA序列比对和生化试验鉴定种属, 并进行高温、酸碱、胆盐耐受性测定, 黏附性测定和安全性测定等多项实验。从乌鳢肠道分离得到2株芽孢杆菌, 经测序及BLAST比对, 发现均为芽孢杆菌属, 其中CA-1为贝莱斯芽孢杆菌(Bacillus velezensis)高同源性菌株, CA-2为枯草芽孢杆菌(Bacillus subtilis)高同源性菌株。通过生化鉴定分别鉴定为CA-1贝莱斯芽孢杆菌和CA-2枯草芽孢杆菌。2株分离菌均为α-溶血, 不具有生物膜, 疏水性57.7%—73.4%, 自凝集性 71.5%—81.3%; 可在强酸强碱环境和低浓度(0.5%)胆盐中存活; 经过不同高温处理后仍可生长; 2株菌对常见的20种抗生素均不耐药以及对大肠杆菌、金黄色葡萄球菌和嗜水气单胞菌有抑制作用。贝莱斯芽孢杆菌CA-1和枯草芽孢杆菌CA-2可在极端环境下生存, 具有良好的黏附性能和一定的安全性, 可作为乌鳢养殖中的潜在益生菌。

     

    Abstract: Probiotics, as a potential antibiotic alternative, can improve digestive function, promote growth, and boost the antioxidant capacity and immunity of aquatic animals. To isolate and identify intestinal Bacillus strains from Channa argus and evaluate their potential as probiotics feed additives. Intestinal samples of Channa argus were collected, and bacteria were extracted using the dilution coating method. The species identification was performed using 16S rRNA sequencing and biochemical tests. A variety of experiments were conducted, including high-temperature, acid-base, and bile-salt tolerance assays, adhesion assays, and safety tests. Two Bacillus strains were isolated from the intestinal tract of Channa argus, and after sequencing and BLAST analysis revealed that the strains belonged to the genus Bacillus, which were mainly categorized into Bacillus velezensis and Bacillus subtilis. Strain CA-1 was identified as Bacillus velezensis and strain CA-2 as Bacillus subtilis based on biochemical characterization. Both strains were α-hemolytic, lacked biofilm formation, exhibited hydrophobicity ranging from 57.7% to 73.4%, and showed auto-aggregation from 71.5% to 81.3%. They were able to live in strong acid and alkaline environments as well as in low concentrations of bile salts (0.5%) and withstood high-temperature treatments. Both bacteria were sensitive to the 20 most regularly used antibiotics and inhibited Escherichia coli, Staphylococcus aureus, and Aeromonas hydrophilus. Bacillus velezensis CA-1 and Bacillus subtilis CA-2 demonstrate resilience in harsh conditions, exhibit strong adhesion characteristics, and are relatively safe, making them promising candidates as potential probiotics for Channa argus culture.

     

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