13 Mai 2015
In a follow-up to last year's groundbreaking presentation of the taxonomic identity and diversity of the gut microbiota (GM) of Hadza hunter-gatherers, Stephanie and Amanda announce a new paper focused on the metagenome of this microbiota. This new paper presents the functional potential of the GM, including both genes dedicated to processing certain food types, as well as antibiotic resistance genes.
Led by the same international team including researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, the University of Bologna, Italy and the Institute of Biomedical Technology, CNR, Milan, this study suggests that, compared to the GM of Westerners, the Hadza GM has more genes to break down both amino acids and a broad variety of complex sugars. These genes give the Hadza GM the ability to get more energy from the non-domesticated and very seasonally varied foods in the Hadza diet.
Interestingly, the Hadza GM contains more different types of carbohydrate active enzymes (CAZymes) than the Italian gut microbiota, including those for alpha amylase, which particularly breaks down starch. This suggests an enhanced capacity for complex carbohydrate metabolism. Furthermore, the genes enriched in the Hadza gut microbiota largely belong to members of the genus Prevotella, which are seen to a higher degree in several other rural communities in Africa and South America. This suggests that these microbes may be opportunistically conferring unique functional traits not acquired in the Western urban gut microbiome. On the other hand, the Italian GM expressed more genes associated with the break down of xenobiotics, which are usually toxic or foreign compounds such as food preservatives or petrochemicals that are plentiful in industrialized urban environments.
In addition to genes for metabolism, the researchers also explored the profile of antibiotic resistance genes in both populations, resulting in one of the most comprehensive cross-population analyses to date. The Hadza GM closely resembles the resistance elements in the natural environment, such as in soil. However, the Italian GM shows the impact of frequent antibiotic exposure, both from food and medicine. This influence was found to be greatest for antibiotics commonly given to livestock, suggesting a strong effect from food derived sources of antibiotic resistance among Western communities.
Gut microbiota are our co-evolutionary partners that help us adapt and thrive through a variety of subsistence strategies across complex environmental landscapes. Their cells outnumber our own human cells ten to one, and the collective fount of genomic information enhances the functional and adaptive potential of both microbiota and human host. The Hadza are one of the last true hunter-gatherer poplations in the world, and studying the functional structure of their microbial symbionts offer us a glimpse of how this mutualism may have played a significant role in influencing host health throughout human evolution.
The paper is available online at: http://dx.doi.org/10.1016/j.cub.2015.04.055