Taxonomic Studies of Predatory Bdellovibrios Based on 16S rRNA Analysis, Ribotyping and the hit Locus and Characterization of Isolates from the Gut of Animals

Schwudke, Dominik; Strauch, Eckhard; Krueger, Monika; Appel, Bernd

doi:10.1078/0723-2020-00042

Cited by 74 publications

(83 citation statements)

References 13 publications

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“…The two predatory strains were cultivated either in liquid cultures with E. coli prey or on double-layer agar plates. In the latter case, prey bacteria were resuspended within the top layer (30). Stationary-phase prey bacteria were harvested by centrifugation and dissolved in the same volume of Bdellovibrio buffer (3 mM ammonium acetate, 3 mM CaCl 2 , 3 mM MgCl 2 , pH 7.5).…”

Section: Methodsmentioning

confidence: 99%

Identification of Genes Essential for Prey-Independent Growth of Bdellovibrio bacteriovorus HD100

et al. 2011

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Bdellovibrio bacteriovorus HD100 is an obligate predatory bacterium that attacks and invades Gram-negative bacteria. The predator requires living bacteria to survive as growth and replication take place inside the bacterial prey. It is possible to isolate mutants that grow and replicate outside prey bacteria. Such mutants are designated host or prey independent, and their nutritional requirements vary. Some mutants are saprophytic and require prey extracts for extracellular growth, whereas other mutants grow axenically, which denotes the formation of colonies on complete medium in the absence of any prey components. The initial events leading to prey-independent growth are still under debate, and several genes may be involved. We selected new mutants by three different methods: spontaneous mutation, transposon mutagenesis, and targeted gene knockout. By all approaches we isolated mutants of the hit (host interaction) locus. As the relevance of this locus for the development of prey independence has been questioned, we performed whole-genome sequencing of five prey-independent mutants. Three mutants were saprophytic, and two mutants could grow axenically. Wholegenome analysis revealed that the mutation of a small open reading frame of the hit locus is sufficient for the conversion from predatory to saprophytic growth. Complementation experiments were performed by introduction of a plasmid carrying the wild-type hit gene into saprophytic mutants, and predatory growth could be restored. Whole-genome sequencing of two axenic mutants demonstrated that in addition to the hit mutation the colony formation on complete medium was shown to be influenced by the mutations of two genes involved in RNA processing. Complementation experiments with a wild-type gene encoding an RNA helicase, RhlB, abolished the ability to form colonies on complete medium, indicating that stability of RNA influences axenic growth.

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Section: Methodsmentioning

confidence: 99%

Identification of Genes Essential for Prey-Independent Growth of Bdellovibrio bacteriovorus HD100

et al. 2011

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“…The thermal denaturation curve of the DNA preparation from strain JSS T gave no indication of contaminating C. crescentus DNA (62-67 mol% G+C; data not shown). Schwudke et al (2001) proposed that the genetic locus hit (for host interaction) was restricted to Bdellovibrio bacteriovorus strains and could be used as a specific probe for this species. Therefore, we screened the genomic DNA of strain JSS T for the presence of the hit locus by PCR amplification (according to Schwudke et al, 2001) and Southern blotting (as described by Flannagan et al, 2004) with a DIG-labelled hit locus probe.…”

Section: How Do Strain Jssmentioning

confidence: 99%

“…Additional chemotaxonomic data would be useful to support this proposal for a novel species of Bdellovibrio. However, these analyses need to be done with preyindependent mutants of predators, a rationale stated by Schwudke et al (2001). The presence of remaining prey cells in a co-culture necessitates their separation from predators by filtration or differential centrifugation.…”

Section: How Do Strain Jssmentioning

confidence: 99%

Bdellovibrio exovorus sp. nov., a novel predator of Caulobacter crescentus

Koval

Hynes

Flannagan

et al. 2013

International Journal of Systematic and Evolutionary Microbiology

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The life cycle, prey range and taxonomic status of a Bdellovibrio -like organism, strain JSST, were studied. Strain JSST was isolated from sewage in London, Ontario, Canada, in enrichment culture with Caulobacter crescentus prey cells. During predation, this strain remained attached to the outside of a stalked C. crescentus cell. No periplasmic growth stage was observed and no bdelloplast was formed. The stalked cells of C. crescentus retained their shape and, after predation, were devoid of cytoplasmic content, as shown by transmission electron microscopy. A periplasmic growth stage has been a definitive character in the description of members of the genera Bdellovibrio , Bacteriovorax , Bacteriolyticum and Peredibacter . This is the first description of an epibiotic predator in this group of prokaryotic predators. The G+C content of the genomic DNA of strain JSST was 46.1 mol%. 16S rRNA gene sequence analysis showed that this strain was related to Bdellovibrio bacteriovorus strains HD100T, 109J, 114 and 127 (90–93 % similarity). Phylogenetic analysis based on 16S rRNA gene sequences grouped strain JSST with the Bdellovibrio cluster, but at a distance from other Bdellovibrio isolates. On the basis of features of the life cycle and phylogenetic data, it was concluded that strain JSST merits classification as the type strain of a novel species, for which the name Bdellovibrio exovorus sp. nov. is proposed (type strain JSST = ATCC BAA-2330T = DSM 25223T).

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“…Predation by BALOs is either periplasmic or epibiotic, with both strategies being carried out by closely related predators (15). BALOs are well distributed in nature, being found in both terrestrial and aquatic ecosystems and possibly in animal (including human) intestines (11,16,17). Because obligate predators cannot replicate in the absence of adequate prey, the structure of BALO populations is under environmental selection (6,7,18), whereas natural selection and arms race may shape predator-prey interactions (19,20).…”

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confidence: 99%

Cell-cycle progress in obligate predatory bacteria is dependent upon sequential sensing of prey recognition and prey quality cues

Rotem

Pasternak

Shimoni

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Predators feed on prey to acquire the nutrients necessary to sustain their survival, growth, and replication. In Bdellovibrio bacteriovorus, an obligate predator of Gram-negative bacteria, cell growth and replication are tied to a shift from a motile, free-living phase of search and attack to a sessile, intracellular phase of growth and replication during which a single prey cell is consumed. Engagement and sustenance of growth are achieved through the sensing of two unidentified prey-derived cues. We developed a novel ex vivo cultivation system for B. bacteriovorus composed of prey ghost cells that are recognized and invaded by the predator. By manipulating their content, we demonstrated that an early cue is located in the prey envelope and a late cue is found within the prey soluble fraction. These spatially and temporally separated cues elicit discrete and combinatory regulatory effects on gene transcription. Together, they delimit a poorly characterized transitory phase between the attack phase and the growth phase, during which the bdelloplast (the invaded prey cell) is constructed. This transitory phase constitutes a checkpoint in which the late cue presumably acts as a determinant of the prey's nutritional value before the predator commits. These regulatory adaptations to a unique bacterial lifestyle have not been reported previously.microbial ecology | bacterial physiology | bacterial cell cycle | predatory bacteria | Bdellovibrio bacteriovorus

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Taxonomic Studies of Predatory Bdellovibrios Based on 16S rRNA Analysis, Ribotyping and the hit Locus and Characterization of Isolates from the Gut of Animals

Cited by 74 publications

References 13 publications

Identification of Genes Essential for Prey-Independent Growth of Bdellovibrio bacteriovorus HD100

Identification of Genes Essential for Prey-Independent Growth of Bdellovibrio bacteriovorus HD100

Bdellovibrio exovorus sp. nov., a novel predator of Caulobacter crescentus

Cell-cycle progress in obligate predatory bacteria is dependent upon sequential sensing of prey recognition and prey quality cues

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