Is the Microbiota Species Specific? Cell paper weighs in.

A just published Cell paper, Gut Immune Maturation Depends on Colonization with a Host-Specific Microbiota, weighs in on the growing evidence that the gut microbiota is specific to a host. In this case, the study shows that non-native microbiotas, including human and rat, colonize a mouse gut, but those bacterial species do not work with the resident mouse cells to mount a proper immune response. Simply stated, you can put non-native microbes in an animal, but you dont get a fit animal back.

Highlights from the paper:

• Mouse and human microbiota differ in bacterial species, primarily within Firmicutes
• Human microbiota (HMb) colonized mice have a global immunodeficiency like GF mice
• HMb induced less T cell proliferation and activation than mouse microbiota (MMb)
• HMb mice are more susceptible to enteric and disseminated infection than MMb mic

Video link of the senior author and Harvard professor, Dennis Kasper, describing the paper:

This work contributes to an emerging body of literature that supports the hypothesis that a minor or major part of the assemblage of the OTUs in the microbiota interact with the host in a specific manner. The consequence of this specificity is that assemblages of bacteria in related species may actually change in composition over time in parallel with the phylogeny of the host species. Thus, the bacterial OTUs could be a general extension of the host's genes, and there is an evolutionary footprint in the changes in both. We saw this in Nasonia wasps (Evolution paper here) and have summarized other evidence in Box 1 of this review (Trends in Ecology and Evolution paper here).

All this makes me wonder how important symbiosis will turn out to be in speciation. If the pace of new discoveries is any indication, it is looking like the old ideas of the 80's and 90's (that symbionts do not assist speciation in any grand way) is going to be entirely reassessed.

Related Blog Posts:

• Speciation by symbiosis (April 26, 2012)
• Is the microbiome part of the organism or the environment? (May 11, 2012)