Sunday, January 24, 2016

Recent Study Reveals Role for Bacterial Viruses in Microbiome Evolution

The microbiome is a complex community of bacteria,
viruses, and other microbes.
Microbial communities are fierce battlegrounds between bacteria and other microbes competing for limited resources. One method some bacteria use to kill their competitors is the production of bacteriocins. Bacteriocins are protein toxins produced by bacteria to limit the growth of related bacteria, thereby providing a competitive advantage to the bacteriocin-producing bacteria. This dynamic is important to our health because it can impact bacterial infections and overall microbiome composition. The group of Nedialkova et al recently added a whole new level of insight into bacteriocins and microbial ecology by linking bacteriocin production to the presence of bacteriophages (bacterial viruses).

Overall this was a pretty straightforward study and a nice read. The research group recognized that Salmonella enteric genome contain a myriad of prophage genomes, which means the virus genome are integrated into the bacterial genome and are waiting to come out into an infectious cycle when the bacteria is stressed (a process called phage induction). This is medically relevant, because many antibiotics can induce bacteriophages.

The group provided evidence for phages playing an important role in colicin release (the Salmonella bacteriocin) by removing the viruses out of the cultured bacterial genomes and observing a resulting decreased ability of the bacteria to release their bacteriocin. They attempted to pinpoint the phage genes involved in bacteriocin release from the bacteria, but this ultimately served to highlight the complex cell signaling involved in bacteriocin production and release. The group wrapped their study up by showing that by affecting colicin "use", the phages impact the evolution of S. enterica by affecting their competitive advantages. This was tested by competing the Salmonella with E coli bacteria that are commonly found in the human gut.

I really like this paper because it provides even more evidence on how important phages are for bacterial functionality and evolution. This role for phages is relevant to isolated bacterial systems, but is also very important for the human microbiome. Phages are important for the structure and function of the human microbiome, and thereby impact human health in a big way. Overall this really shows how complex the human microbiome is, and how important it is to study the phages in these communities, instead of focusing only on the bacteria.

So now that we have previewed the paper, I suggest looking it up and reading the real thing. It is a well written and straightforward paper that is worth reading. And finally, if you noticed I left anything out or missed a point you think is worth bringing up, shoot me a comment below. You should also always feel free to reach out on Twitter or by email.

Works Cited

Nedialkova LP, Sidstedt M, Koeppel MB, Spriewald S, Ring D, Gerlach RG, Bossi L, & Stecher B (2015). Temperate phages promote colicin-dependent fitness of Salmonella enterica serovar Typhimurium. Environmental microbiology PMID: 26439675

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