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

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.

Key words:Keywords: shrimp mariculture pond， Bdellovibrio-and-like organisms， Halobacteriovoracaceae， Peredibacteraceae，16S rRNA gene，diversity