Variation in rural African gut microbiota is strongly correlated with colonization by Entamoeba and subsistence

Abstract

The human gut microbiota is impacted by host nutrition and health status and therefore represents a potentially adaptive phenotype influenced by metabolic and immune constraints. Previous studies contrasting rural populations in developing countries to urban industrialized ones have shown that industrialization is strongly correlated with patterns in human gut microbiota; however, we know little about the relative contribution of factors such as climate, diet, medicine, hygiene practices, host genetics, and parasitism. Here, we focus on finescale comparisons of African rural populations in order to (i) contrast the gut microbiota of populations inhabiting similar environments but having different traditional subsistence modes and either shared or distinct genetic ancestry, and (ii) examine the relationship between gut parasites and bacterial communities. Characterizing the fecal microbiota of Pygmy hunter-gatherers as well as Bantu individuals from both farming and fishing populations in Southwest Cameroon, we found that the gut parasite Entamoeba is significantly correlated with microbiome composition and diversity. We show that across populations, colonization by this protozoa can be predicted with 79% accuracy based on the composition of an individual's gut microbiota, and that several of the taxa most important for distinguishing Entamoeba absence or presence are signature taxa for autoimmune disorders. We also found gut communities to vary significantly with subsistence mode, notably with some taxa previously shown to be enriched in other hunter-gatherers groups (in Tanzania and Peru) also discriminating hunter-gatherers from neighboring farming or fishing populations in Cameroon. Funding: This work was funded by the Howard Hughes Medical Institute (HHMI) and the French National Agency for Research (ANR; grant ANR-11-BSV7-0011). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Competing Interests: The authors declared that no competing interests exist. Author SummaryThe community of microorganisms inhabiting the gastrointestinal tract plays a critical role in determining human health. It's been hypothesized that the industrialized lifestyle, marked by a diet rich in processed foods, higher use of antibiotics, increased hygiene, and exposure to various chemicals, has altered microbiota in ways that are harmful. Studies have addressed this by comparing rural and industrialized populations, and have found that they systematically vary in their gut microbiome composition. Nevertheless, the relative influence of host genetics, diet, climate, medication, hygiene practices, and parasitism is still not clear. In addition, microbial variation between nearby human populations has not been explored in depth. Moreover, The World Health Organization estimates that 24% of the world's population, concentrated in developing countries, is infected with gut parasites. Despite this, and evidence for direct interactions between the immune syste...

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