This article in Nature Communications addressed the much-debated issue of microbiota stability over time. The idea of a “tipping element” is a hat tip to the field of climate change research, where it means a threshold at which a small perturbation in one element can qualitatively change a system.
Here, Lahti and collaborators described a deep phylogenetic analysis of the gut microbiota in 1,000 western adults. They found groups of bacteria that showed robust bistable abundance distributions: that is, in a given individual they were either present in abundance or nearly absent, and in quantities in between them were less temporally stable. Also, these groups of bacteria were correlated with host health factors. Consequently, the researchers suggested that these bistable taxa could serve as indicators of the overall community state. They observed, for example, robust bimodal abundance distribution for Bacteroides fragilis, Prevotella melaninogenic or two groups of uncultured Clostridiales. However, the bimodal pattern did not appear to be affected by short-term dietary changes, but they were associated with factors such as ageing or weight.
Finally, the authors hypothesized that these bistable groups are the “tipping elements” of the gut microbiota, whose critical transitions could have important health implications and diagnostic potential.
Lahti L et al. (2014) Tipping elements in the human intestinal ecosystem Nature Communications 5:4344. doi:10.1038/ncomms5344