Understanding the reasons why intestinal bacterial communities differ between individuals and within individuals over time represent major challenges for microbiome researchers. Researchers at Kiel University and the Max Planck Institute for Evolutionary Biology in Germany reveal that the recent dietary history of house mice living in the wild is a major determinant of the type of bacterial community present in their gut at a given time. The article appeared on May, 27th 2014 in the online edition of Proceedings of the National Academy of Sciences.
As part of the German Research Foundation's Cluster of Excellence "Inflammation at Interfaces," the team including evolutionary biologists and microbiologists were motivated to gain a greater understanding of intestinal bacterial community dynamics in the house mouse, which is an important model organism for studying chronic inflammatory disorders such as inflammatory bowel disease.
To gain insight, the researchers turned to house mice in their natural environment, where they encounter a variety of different food sources. Their analyses revealed that similar to recent studies in humans, individual mice could be classified into one of two clusters of bacterial community types, a concept known as "enterotypes."
"What really lead us down the path to understanding these two community types were observations made between free-living mice and those moved to the lab and given a standard lab chow diet," says Professor John Baines, the senior author of the study. "While both mouse enterotypes were consistently present in the wild, mice housed in the lab had only one of these enterotypes."
Interestingly, the single lab-associated mouse enterotype displayed characteristics similar to an analogous enterotype in humans that is associated with greater carbohydrate consumption. To test this possibility in mice, the researchers next turned to colleagues conducting archaeological research at Kiel University, who used their recently developed statistical method to help reconstruct the diet of wild mice using chemical signatures left behind in their tissues.
"Indeed, the wild mice display significant differences in the relative intake of carbohydrate-rich food sources according to their enterotype classification," says Doctor Ricardo Fernandes, a member of Kiel University's Graduate School "Human Development in Landscapes."
Further, the researchers were able to document shifts in enterotype status within one week. The authors acknowledge that more intensive future research is necessary to understand the dynamics of human enterotypes, but speculate that the fast metabolism of a small mammal such as the mouse may play a role.
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