More Fecal Findings!

At the risk of developing a complex that all I talk about is fecal matter, for the second time this week I would like to bring your attention to another study that focuses on the gut and its microbial habitat. A couple of days ago I discussed the challenge of identifying the huge number of microbes found in our bodies and the impact that our microbiome has on our physical health (see fecal pharma post).

In today’s issue of Nature, Alejandro Reyes from Washington University’s school of medicine published a paper showing that although the fecal microbiome is relatively stable between related individuals, the fecal virome exhibits a greater degree of inter-person variability and a lesser degree of intra-person variability. These findings are quite surprising since one would expect bacteriophage expression to be heavily dependent on its microbial environment and therefore to follow a similar pattern to microbial expression. Instead, this study shows that although there were similar microbes in the feces of related individuals their fecal viral expression was quite different. The authors conclude “that a predatory viral-microbial dynamic, manifest in a number of other characterized environmental ecosystems, is notably absent in the very distal intestine.” In other words, our traditional understanding of the relationship between viruses and bacteria in the laboratory setting is challenged when studied in anin-vivo environment.

Below is a this week’s Nature podcast which contains an interview with the study’s principal author Jeffrey Gordon. Scroll over to 15:04 to hear the interview.

The Poo Virome

This study is especially interesting considering the findings of an Israeli group which was published in Molecular Systems Biology back in October 2009. In that study, the authors showed that bacteriophages are strongly tuned to match their unique hosts while viruses that infect humans resemble all mammalian hosts equally. This seems to support Reyes’ et al. initial hypothesis that since related individuals exhibit a high degree of similarity in their fecal microbial expression it would be expected that inter-personal fecal bacteriophage expression would be similar as well. As such, the Reyes paper has left us with more questions than answers regarding fecal viral expression.

The fecal pharma post demonstrated the importance of microbiome research in the context of human health. Based on Reyes’ findings, those involved in the Human Microbiome Project would be wise to incorporate virome analysis into their research as well.

Alejandro Reyes, Matthew Haynes, Nicole Hanson, Florent E. Angly, Andrew C. Heath, Forest Rohwer, & Jeffrey I. Gordon (2010). Viruses in the faecal microbiota of monozygotic twins and their mothers Nature, 466, 334-338 : 10.1038/nature09199

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