What is it about?
The animal microbiota (including the human microbiota) plays an important role in keeping the physiological status of the host healthy. Research seeks greater insight into whether changes in the composition and function of the microbiota are associated with disease. We analyzed published 16S rRNA and shotgun metagenomic sequencing (SMS) data pertaining to the gut microbiotas of 99 subjects monitored over time. Temporal fluctuations in the microbial composition revealed significant differences due to factors such as dietary changes, antibiotic intake, age, and disease. This article shows that a fluctuation scaling law can describe the temporal changes in the gut microbiota. This law estimates the temporal variability of the microbial population and quantitatively characterizes the path toward disease via a noise-induced phase transition. Estimation of the systemic parameters may be of clinical utility in follow-up studies and have more general applications in fields where it is important to know whether a given community is stable or not.
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Why is it important?
The human microbiota correlates closely with the health status of its host. This article analyzes the microbial composition of several subjects under different conditions over time spans that ranged from days to months. Using the Langevin equation as the basis of our mathematical framework to evaluate microbial temporal stability, we proved that stable microbiotas can be distinguished from unstable microbiotas. This initial step will help us to determine how temporal microbiota stability is related to a subject’s health status and to develop a more comprehensive framework that will provide greater insight into this complex system.
Perspectives
On the one hand, the healthy subset in each study that we analyzed has less variability than the nonhealthy subset, when adult subjects are considered. Nevertheless, the variability parameter was higher in the healthy subset in one particular case: the study of discordant twins suffering from kwashiorkor disease. In this respect, research has shown that the infant microbiota needs to develop toward a definite, adult state. This implies that temporal variability is greater in children than in healthy adults, who should be temporally stable. Thus, our results could indicate that this variability is necessary to reach that adult state. On the other hand, some taxa showed higher stability than other more dominant taxa, forming what we called “rank stability islands” for medium-ranked taxa. These taxa are displaying a moderately stable index (Rank Stability Index roughly over 70%) despite being not dominant. The presence of “rank stability islands” among medium-ranked taxa is an interesting feature revealed by the analysis of rank stability in different time periods. In the lifestyle study (the one with the longest time series), this stability was compromised when the period was not an ordinary one, suggesting that those taxa were sensitive to some changes in the lifestyle.
Jose Manuel Martí
University of California Berkeley LBNL
Read the Original
This page is a summary of: Health and Disease Imprinted in the Time Variability of the Human Microbiome, mSystems, March 2017, ASM Journals,
DOI: 10.1128/msystems.00144-16.
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