一株菲律宾蛤仔肠道潜在益生菌的分离鉴定及其应用效果分析

Isolation and application of a bacterial strain with potential probiotic effects from intestinal tract of Manila clam(Ruditapes philippinarum)

为筛选对菲律宾蛤仔(Ruditapes philippinarum)具有潜在益生效果的细菌,从健康蛤仔(平均体质量为14.51 g±1.18 g)肠道分离得到可培养细菌,利用体外平板试验检测其产酶能力,从中筛选产酶菌株并进行形态学观察和分子鉴定;利用平板计数法绘制吸光度值-菌体数标准曲线,检测细菌对酸和胆盐的耐受性;通过对蛤仔幼贝进行攻毒,检验其安全性;最后通过养殖试验,检验其对蛤仔幼贝的益生作用。结果表明:从健康蛤仔肠道分离出1株同时具备产淀粉酶、蛋白酶和脂肪酶能力的细菌(命名为C26);菌株C26为革兰氏阴性菌,鉴定为假交替单胞菌属(Pseudoalteromonas);在pH>4.5、胆盐质量浓度为0~0.1 g/100 mL的条件下,菌株C26具有良好的耐受性;菌株C26对蛤仔幼贝无致病性,且可显著提高蛤仔幼贝的增重率(P<0.05)。研究表明,筛选出的菲律宾蛤仔源假交替单胞菌C26对蛤仔具有安全性,并对蛤仔具有益生作用,该菌为丰富蛤仔益生菌菌种资源提供了有益参考。

With an attempt to screen bacteria with potential probiotic effects on Manila clam(Ruditapes philippinarum),culturable bacteria were first isolated from the intestinal tract of the healthy clam and then subject to enzyme-producing ability examination by in vitro plate experiment.Those enzyme-producing strains were,morphologically observed and molecularly identified by plate counting method and the standard curve between the absorbance value and the bacterial cell number.The bacterium was examined for acid and bile salt tolerance,and the safety of the enzyme-producing bacterium on R.philippinarum larvae by challenging test.The Manila clam juveniles were reared to examine growth promoting effects.The results showed that a bacterial strain isolated from the intestinal tract of healthy clams designated as C26 produced amylase,protease and lipase was gram-negative and belonged to the genus of Pseudoalteromonas,with tolerabce to pH value of higher than 4.5 and a bile salts concentration ranging from 0 g/100 mL to 0.1 g/100 mL.In addition,Strain C26 had no pathogenicity to R.philippinarum and significantly improved the weight gain rate of the juveniles(P<0.05).To sum up,a safe Pseudoalteromonas strain C26 was screened and had probiotic effects on Manila clam larvae,which provides foundation for enrichment of the Manila clam probiotic strain resources.