Microbe Profile: Bdellovibrio bacteriovorus: a specialized bacterial predator of bacteria.

Bdellovibrio bacteriovorus is an environmentally-ubiquitous bacterium that uses unique adaptations to kill other bacteria. The best-characterized strain, HD100, has a multistage lifestyle, with both a free-living attack phase and an intraperiplasmic growth and division phase inside the prey cell. Advances in understanding the basic biology and regulation of predation processes are paving the way for future potential therapeutic and bioremediation applications of this unusual bacterium.

Keeping it together: absence of genetic variation and DNA incorporation by the predatory bacteria Micavibrio aeruginosavorus and Bdellovibrio bacteriovorus during predation.

The use of predatory bacteria as a potential live therapeutic to control human infection is gaining increased attention. Earlier work with Micavibrio spp. and Bdellovibrio spp. has demonstrated the ability of these predators to control drug-resistant Gram-negative pathogens, Tier-1 select agents and biofilms. Additional studies also confirmed that introducing high doses of the predators into animals does not negatively impact animal well-being and might assist in reducing bacterial burden in vivo. The survival of predators requires extreme proximity to the prey cell, which might bring about horizontal transfer of genetic material, such as genes encoding for pathogenic genetic islands that would indirectly facilitate the spread of genetic material to other organisms. In this study, we examined the genetic makeup of several lab isolates of the predators Bdellovibriobacteriovorus and Micavibrioaeruginosavorus that were cultured repeatedly and stored over a course of 13 years. We also conducted controlled experiments in which the predators were sequentially co-cultured on Klebsiella pneumoniae followed by genetic analysis of the predator. In both cases, we saw little genetic variation and no evidence of horizontally transferred chromosomal DNA from the prey during predator-prey interaction. Culturing the predators repeatedly did not cause any change in predation efficacy.

Isolation of Bdellovibrio bacteriovorus from a tropical wastewater treatment plant and predation of mixed species biofilms assembled by the native community members.

It is reported here that a predatory bacterium belonging to the Genus Bdellovibrio, was isolated from activated sludge at the Ulu Pandan Water Reclamation Plant, Singapore. 16S rDNA gene sequencing analysis revealed that this isolate was 99% identical to 'Bdellovibrio bacteriovorus strain Tiberius' and hence is designated as 'Bdellovibrio bacteriovorus UP'. Using a novel approach based on fluorescence in situ hybridization (FISH), a prey cell density-dependent growth pattern of B. bacteriovorus UP was established. B. bacteriovorus UP preyed upon a broad range of bacterial species (60 species) isolated from the activated sludge. Except for Ochrobactrum anthropi, all Gram-negative species were sensitive to predation by B. bacteriovorus UP irrespective of the mode of growth (planktonic or biofilm). Similarly, the predation-sensitive species were not protected by the predation-resistant species, O. anthropi, as determined in multiple dual-species planktonic and biofilm consortia. Given the broad prey spectrum, B. bacteriovorus UP may impact functional community members, which are largely members of the Proteobacteria. Thus, these results provide an important insight to the role of predatory bacteria in shaping of community structure and function in both natural and engineered ecosystems.