Isolation, identification and prey range of Halobacteriovorax sp. BALOs10

Abstract:

[Objective] The purpose of the study was to isolate and identify Bdellovibrio-and-like organisms (BALOs) strains from seawater and increase the known species richness of BALOs. [Methods] Vibrio alginolyticus LF TCBS 15 was used as host bacterium to isolate BALOs from seawater samples with seawater agar double-layer plate method. The seawater samples were collected from Daya bay of Shenzhen, China. The morphology of the cells was observed by light microscopy and transmission electron microscopy. 16S rDNA was used for phylogenetic analysis to complete molecular identification. The prey range on 16 different strains and the effects of NaCl, pH and temperature on the growth of strain BALOs10 were determined by double-layer plate filter paper method.[Results] A novel strain, BALOs10, was isolated using V. alginolyticus LF TCBS 15 as prey. The plaques are round, transparent and the edges were smooth and tidy. The cells are curved (0.21-0.44 μm diameter×1.25-1.87 μm long) with a single polar flagellum. Optimum growth occurs at 35-37℃, pH 7-8 and in the presence of 2%-3% (W/V) NaCl. Prey range on 16 tested strains showed that strain BALOs10 lysed 9 different strains, corresponding to 56.3% of lysis rate, and was especially susceptive to Vibrio and Marinobacter. 16S rDNA sequence analysis indicates that BALOs10 was most closely related to Halobacteriovorax marinus SJ with 92.14% similarity, demonstrating that the strain may represent a novel species. Therefore, Halobacteriovorax sp. BALOs10 is proposed.[Conclusion] strain BALOs10 may represent a novel predator of genus Halobacteriovorax, which will enrich the species resource of BALOs and lay the material foundation for subsequent application and theoretical research.