银鲫肠道内抑制嗜水气单胞菌的潜在益生菌筛选及其特性研究

从养殖的银鲫(Carassius auratus gibelio)肠道中分离纯化得到60株具有不同特征的菌株,以嗜水气单胞菌(Aeromonas hydrophila)为指示菌,点种法初筛得到12株菌株,再通过牛津杯实验筛选出4株对嗜水气单胞菌有明显抑制作用(抑菌圈直径在14 mm以上)的益生菌疑似株,并进行了耐热试验、耐酸试验和人工肠液耐受试验,筛选出最符合益生菌功能特性的菌株YJ-9。该菌株在90℃高温水浴30 min后相对存活率为1.51%,在pH3的液体培养基中4 h内相对存活率为8.37%,活菌数都保持在106 CFU/mL以上,并且可以在人工模拟肠液中缓慢生长。在急性毒力实验中,10倍于实验剂量的菌株YJ-9对银鲫无毒,动物保护实验证明菌株YJ-9能有效增强银鲫对嗜水气单胞菌的免疫抵抗力,相对保护率达到80%。研究结果表明,菌株YJ-9可以作为一个新的饲用微生态制剂候选菌种。

Selection and characteristic analysis of potential probiotic strains against Aeromonas hydrophila from the intestine of Carassius auratus gibelio

60 strains of bacteria with different characters were isolated from the intestine of silver crucian carp.Using Aeromonas hydrophila as the index bacteria,12 strains of bacteria were identified by dot-inoculating method,and 4 strains of potential probiotic were selected with various bacteriostatic ability against A.hydrophila(inhibition circle to pathogens>14MM) by Oxford cup test.According to their tolerances of high temperature,low pH,artificial intestinal juice,the strain YJ-9 was confirmed with the best probiotic functional characteristics.Under the condition of water-bath of 90 ℃ for 30 min and pH 3 in Nutrient Broth medium for 4h,its relative survival rate were 1.51% and 8.37%,and the number of viable cells was above 106 CFU/mL.It could grow slowly in the artificial intestinal juice.In addition,it was safe for the silver crucian carp when they were challenged by the 10 times experimental dose.The relative percent survival of YJ-9 reached 80% by animal protection test.The results indicated that YJ-9 could be used as a new candidate probiotic strain for microbial ecological feed additives.