水产养殖用蛭弧菌类生物制剂的检测

通过双层平板法以不同细菌为宿主测定了八个厂家蛭弧菌类生物制剂的噬斑含量及噬斑分离物的宿主裂解范围；以三对靶向不同类群蛭弧菌类生物的特异引物对各产品及其噬斑分离物进行了PCR检测；对两株代表性蛭弧菌分离物的16S rRNA基因进行了测序，并通过构建蛭弧菌科进化树分析了它们的系统地位。结果表明被检测的绝大多数蛭弧菌类生物制剂质量不合格，仅两个样品被蛭弧菌科特异引物检测为阳性，被双层平板法证实有噬斑出现。其中一个样品JSF中存在两种形态和宿主范围不同的噬斑分离物，且不同宿主菌计数结果存在明显差异。16S rRNA基因序列分析表明这两种噬斑分离物JSF1和JSF2，分别属于蛭弧菌科的噬菌蛭弧菌(类群1)和未定种的类群5。但另一样品的噬斑分离物则被证实为非蛭弧菌类生物。

The detection of Bdellovibrio-and-like organisms in commercial preparations used for aquaculture

Bdellovibrio-and-like organisms (BALOs) are obligate predatory bacteria and have potential for biocontrol of pathogenic bacteria. In order to provide scientific reference for study, application and market supervision of the BALOs preparations, this study was to evaluate the quality of commercial BALOs preparations used for aquaculture. Using double layer agar technique, the plaques content of BALOs preparations manufactured by eight companies were counted with different bacteria as preys, and the prey range of plaque isolates were tested. The preparations and the plaque isolates were also identified by PCR with three pairs of taxon-specific primers targeting various BALOs groups. The 16S rRNA genes of two representative Bdellovibrionaceae isolates were sequenced and compared with that of related sequences, and the phylogenetic tree of Bdellovibrionaceae was constructed based on genetic distance analysis. The results showed that most of the BALOs preparations being examined were not qualified, only two of the eight preparations gained positive amplification by Bdellovibrionaceae primers, and showed visible plaques on the double layer agar. One of the two Bdellovibrionaceae positive preparations, JSF, had two kinds of plaque isolates with different morphologies and prey patterns, and significant differences were found when counted with different preys. About 1.4 kb 16S rRNA genes were sequenced and deposited in the GenBank with accession numbers EU884925 and EU884926 for the two kinds of plaque isolates, JSF1 and JSF2, respectively. Based on the phylogenetic analysis of 16S rRNA gene sequences, JSF1 and JSF2 were identified as B. bacteriovorus (cluster 1) and the species undefined cluster 5 in Bdellovibrionaceae, respectively. However, the plaque isolates of the other preparations contained no BALOs.