湛江海水虾池免培养蛭弧菌类生物的多样性

Diversity of Bdellovibrio-and-like organisms from shrimp mariculture ponds in Zhanjiang

摘要:

摘要:【目的】揭示湛江地区海水虾池蛭弧菌类生物(Bdellovibrio-and-like organisms，BALOs)多样性特点，为了解BALOs在虾池生态系统中的作用与合理应用其防治养殖对虾细菌病害提供基础。【方法】从8个热带海水虾池采集水样，提取总DNA，利用BALOs科特异引物对水样总DNA进行扩增，通过构建16S rRNA基因克隆文库与系统发育分析，对虾池水体BALOs多样性和种群结构进行研究。【结果】从嗜盐噬菌弧菌科(Halobacteriovoracaceae)和吞菌弧菌科(Peredibacteraceae)克隆文库中分别获得726个和664个有效克隆子，在16S rRNA基因序列99.5%相似性水平上分别划分为68和44个OTUs(operational taxonomic units)。在16S rRNA基因序列97%相似性上，嗜盐噬菌弧菌可划分为37个种群，且绝大多数属于未培养型，但仅有的5个可培养类群占总文库克隆数量43.5%，其中可培养类群IX 和未培养类群B28分别是最优势和次优势者;吞菌弧菌文库共包含28个种群，未培养类群pa12最为优势，唯一可培养类群A3.12是第2优势者。嗜盐噬菌弧菌与吞菌弧菌多样性大小随盐度高低呈相反趋势，但两者合起来的总BALOs 多样性大小在不同虾池间则比较接近。【结论】湛江地区海水虾池中普遍存在高度多样的嗜盐噬菌弧菌和吞菌弧菌种群，盐度显著影响虾池BALOs种群结构组成。

Abstract:

Abstract:［Objective］ Bdellovibrio-and-like organisms (BALOs) are small-sized，parasitic bacteria that rely on other Gram-negative bacteria for survival． Our work aimed to characterize the community diversity of BALOs associated with tropical shrimp ponds．［Methods］We collected water samples from eight shrimp ponds culturing Litopenaeus vannamei，in Zhanjiang，China，and extracted total DNA of the samples．Then the 16S rＲNA gene clone libraries were constructed following PCR amplification with BALOs family-specific primers． The community composition and structure of BALOs were further analyzed based on phylogenetic analysis．［Results］A total of 726 and 664 valid clones were obtained from the 16S rＲNA gene libraries of families Halobacteriovoracaceae and Peredibacteraceae，respectively． Subsequently，they were respectively grouped into 68 and 44 OTUs (operational taxonomic units) at 99.5% sequence similarity，and assigned into 37 and 28 clusters at 97% similarity． For the Halobacteriovoracaceae libraries，most clusters were so far uncultured with the exception of 5 members，which accounting for 43.5% clones． And the cultivable cluster IX and the uncultured cluster B28 were the first and second dominant ones respectively． For the Peredibacteraceae libraries，the cluster pa12 and the only cultivable cluster A3.12 were the first and second dominant ones respectively．Notably，the values of Shannon diversity indices of Halobacteriovoracaceae and Peredibacteraceae tend to be reversed with the change of salinity，but the total BALOs diversities among the eight shrimp ponds were similar.［Conclusion］Shrimp mariculture ponds in Zhanjinag harbor a high diversity of BALOs comprising of Halobacteriovoracaceae and Peredibacteraceae，and salinity affect their community structure and composition greatly.