A novel review, led by Dr. Andrés Moya from the University of Valencia (Spain) and Dr. Manuel Ferrer from the Institute of Catalysis at Spanish National Research Council in Madrid (Spain), argues that a network-biology approach can help us understand how our gut microbiota is continuously changing in the gut environment.
The ecosystem of bacteria in the human gut operates dynamically, like any other human organ. Gut microbiota stability may be affected within a temporal framework and in this context bacteria turnover is a healthy feature expected in the gut. In order to ensure stability in the face of constant disturbance, microbiota species are continuously interchangeable by means of the metabolites produced by the action of gene products contained in the gut bacteria. Besides considering microbial composition and function, it is important to take into account, over time, the contribution of resistance (no changes in microbiota composition after being subjected to disturbance), resilience (restoration of the initial composition after disturbance), and functional redundancy (recovering of the initial function despite compositional changes). These modifications are produced along a continuum and are shaped by age, geography, lifestyle-related factors, and medication. For instance, redundancy in the infant gut may be higher than that found in the adult gut.
Microbial genes and proteins and their metabolites in the gut grow from a simple structure in early life -usually dominated by bifidobacteria- to a complex structure in adults. During the first 3 years of life, the microbial diversity increases to reach a level similar to that in adulthood. In adults, the commensal microbial communities are generally stable, but the relative abundance of bacteria and the microbial diversity can undergo dynamic changes as a result of its interactions with diet, genotype/epigenetic composition and the physiological state of the individual. The researchers used the analogy of a ball rolling down a mountain to describe different routes and stages in which the intestinal microbiota develops throughout lifespan.
For a better understanding of the gut microbial community, authors highlight the need to focus on levels corresponding to active genes, proteins, and metabolites rather than studying the microbiota only from the compositional and functional perspectives.
To sum up, our gut microbiome is relatively stable but it is also ever-changing. There is a need to develop more functional and integrative studies of microbiota, beyond time-course compositional descriptions.
Moya A, Ferrer M. Functional redundancy-induced stability of gut microbiota subjected to disturbance. Trends Microbiol. 2016. doi:10.1016/j.tim.2016.02.002.