杂色鲍肠道益生菌的分离和鉴定

从杂色鲍(Haliotis diversicolor)肠道内,共分离出84株细菌,经16S rRNA基因序列比对,共产生了35种类型(OTU),分属于17个属,利用纸片扩散法进行了细菌消化酶活性及抑菌活性检测.有75株菌在不同程度上表现出淀粉酶活性、蛋白酶活性、脂肪酶活性、琼胶酶活性、纤维素酶活性或褐藻酸钠酶活性；有24株菌不同程度地抑制2～8株致病菌的生长.结合实验结果,对9株潜在益生菌进行溶血实验检测及动物安全性实验.其中AP12和AP34不产生溶血素,并且在菌株浓度108 CFU/g时对鲍无明显的毒害作用,表明此2株细菌可以作为潜在的益生菌应用于杂色鲍的养殖.AP34具有5种消化酶活性,与fu同温层芽孢杆菌(Bacillus stratosphericus)16S rRNA基因序列同源性最高,为99.87％；AP12对8株致病菌均表现出较强的抑菌活性,该菌16S rRNA基因序列与济州岛褐色杆菌(Phaeobacterdaeponensis)相似性最高,为98.63％.

Isolation and Characterisation of Putative Probiotics from Haliotis diversicolour

The use of probiotics provides a potential alternative method in aquaculture.This study was designed to search for probiotics to improve growth rate and disease resistance of farmed abalone,Haliotis diversicolour.Potential probiotics were selected from the digestive tract of cultured abalones.The selection was based on five criteria: strain identification,digestive enzyme activity assay,pathogen inhibition potential,hemolytic activity assay and two-month farm trials with putative probiotics-supplemented diet.This study isolated 84 strains which were divided into thirty-five operational taxonomic units(OTUs) and 17 genera,based on 16S rRNA gene sequencing.The results showed that 89% of screened bacteria(n=84) showed digestive enzyme activity.Only one isolate AP34 could use all the five substances(soluble starch,nonfat dry milk,glyceryl-tributyrate,CM-cellulose,sodium alginate) provided as nutrition.24 out of 84 strains had antagonistic properties towards pathogens.Only one isolate AP12 could inhibit all the eight pathogens.Furthermore,both AP12 and AP34 showed no hemolytic activity,and the two-month farm trials showed the two isolates were not harmful to cultured abalones.AP12 and AP34 have 99.87% and 98.63% 16S rRNA gene sequence similarities with Bacillus stratosphericus and Phaeobacter daeponensi,respectively.They have promising potential as probiotics for commercially produced H.diversicolour.