The latest revelation in human gut microbiome research is the gut bacterial profiles of fifteen tribal populations representing four geographic regions (Assam, Telangana, Manipur and Sikkim) from India. The study by Dehingia, et al. (2015), Gut bacterial diversity of the tribes of India and comparison with the worldwide data (see References), is a good addition to the knowledge base of gut microbiome profiles across various human populations (Dehingia et al., 2015).
Why is this study relevant and important? Because most of the tribes around the world represent a gut microbiome profile of human ancestral lifestyle, one that was unaffected by “junk” food and was more physically active. Several lifestyle-associated disorders/diseases like type 2 diabetes, metabolic syndrome, and obesity have been linked to variations in human gut microbiome composition and function. Thus, having the knowledge of our ancestral gut microbiome is a good starting point to identify what changes have occurred since the industrialization of our civilization and how they have possibly affected our health.
Migration by humans has led to a large genetic admixture, and hence most of the modern population has mixed genetic makeup. Endogamous Indian tribal groups represent genetically isolated populations and thus provide preserved genetic reserves for disentangling genetic and gut microbiome associations. Dehingia, et al. observed that genetics and environment explained the differences in gut bacterial composition. Interestingly, the next generation sequencing technique could not capture this difference, but an old trusted technique, DGGE (density gradient gel electrophoresis) was able to reveal strain level differences. This observation highlights the need to understand strain level differences in microbiome profiles.
The other interesting finding is the shared high abundance of genus Prevotella in Indian tribes and other unmodernised human populations around the world. This raises the potential for looking at Prevotella as a marker of ancestral dietary habits. Functional implications of this genus are yet not well understood compared to counterparts such as Akkermansia and Faecalibacterium, which commonly dominate the gut microbiome of individuals with a modern lifestyle (Belzer and de Vos, 2012; Miquel, et al., 2013). Thus, culturing studies aimed at isolating Prevotella from Indian tribes would be important for studying the functional role of these bacteria.
The Indian population is the most diverse and multicultural human populace and provides a challenge for gut microbiome studies (Shetty et al., 2013). We previously highlighted the importance of studying this population, especially the tribes, as in depth as we study the rest of the population around the world. The Indian tribes represent ‘virgin’ territory for gut microbiome studies and can provide clues regarding the evolution of the gut microbiome in humans as a result of modernisation (Shetty SA, et al., 2013). The next question that arises from studies on tribal populations around the world is: Can these populations be the source of the next generation of probiotics which can be used to modulate our gut microbiota in a way that improves health?
References:
Belzer, C., and de Vos, W.M. (2012) Microbes inside—from diversity to function: the case of Akkermansia. The ISME journal 6: 1449-1458.
Dehingia, M., Thangjam devi, K., Talukdar, N.C., Talukdar, R., Reddy, N., Mande, S.S. et al. (2015) Gut bacterial diversity of the tribes of India and comparison with the worldwide data. Scientific reports doi:10.1038/srep18563
Miquel, S., Martín, R., Rossi, O., Bermúdez-Humarán, L.G., Chatel, J.M., Sokol, H. et al. (2013) Faecalibacterium prausnitzii and human intestinal health. Current Opinion in Microbiology 16: 255-261.
Shetty, S.A., Marathe, N.P., and Shouche, Y.S. (2013) Opportunities and challenges for gut microbiome studies in the Indian population. Microbiome 1: 24.
