The δ-proteobacteria phylum encompasses a wide range of
microorganisms which in turn occupy a huge range of niches. There is a class of
terrestrial bacteria classified under the Bdellovibrio
genera which encompass a predatory group of very small bacteria including,
until recently, bacteria found in the marine environment. Subsequent genetic
analysis revealed vast differences and the marine bacteria were reclassified
under Bacteriovorax genus. The
predatory bacteria act in a similar way to a virus; as in, once the motile-phased
Bacteriovorax attaches to a specific prey’s
(in the Bacteriovorax case a gram-negative
bacteria) outer membrane, the whole bacterium migrates through the membrane
into the periplasmic space where it switches from the predatory phase to a growth
phase. Eventually the prey cell bursts under the pressure and many new motile Bacteriovorax are ejected. Bacteriovorax marinus is ubiquitous in
the marine environment, with higher distributions in the higher salinity environments
like the Open Ocean and seas.
This study completely sequenced the genome of Bacteriovorax marinus isolated from the
US Virgin Islands and found that it conformed to most of the characteristics of
the δ-proteobacteria Phylum. 35% of the genome had a unique gene content which isn’t
in current gene librarys. The new genes are distributed throughout the genome
and not confined to specific regions, this coupled to the fact that 25% of the
sequences are closely related to bacterial sequences suggests that the new
genes are acquired from previous preyed-upon bacteria. As B.marinus has been shown in
vitro to infect a wide variety of bacteria and given the huge numbers of
bacteria which have yet to be identified/cultured/sequenced from the ocean the
new genes could theoretically have come from unknown bacteria. By comparing the
genome to terrestrial predatory bacteria in the Bdellovibrio genus 291 gene orthologues were identified as possibly
being key to the predatory-specific process.
Another interesting point which the authors ended the paper
on is the possibilities of using predatory bacteria as therapeutic agents
within medicine. To do this the mechanisms of the specificities of the
predation must be understood, and having a complete genome sequence is a
stepping stone toward this understanding. Also the halophillic nature of Bacteriovorax sp. lends itself perfectly
to the high salt content in the human body.
This paper was very good and an interesting read if you
gloss over the many confusing figures of gene maps. The next step would be to
compare the genomes of the B.marinus from
USA waters to some isolated in different geographical locations to identify the
core genome for this genus of bacteria and which genes are part of the
pan-genome.
Nice post, is the author suggesting that the future implications may be to use this bacteria in a fashion similar to phage therapy?
ReplyDeleteYes that is what was indicated. Obviously its an early stage theory so far but theoretically it makes sense as infectious bacteria will have different cell receptors. But it would be interesting to see the effects on the natural gut microbiota. As this is one of the main problems with oral anitbiotics leading to nosocomial diseases.
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