Tracing the evolutionary relationships of the oral microbiome in genetically diverse populations

The oral microbiome is acquired at birth, reaches its full diversity during childhood, and maintains itself relatively stable and resilient to stresses throughout the individual's adult life. The restricted mother-to-child vertical mode of transmission and the high genetic diversity observed in members of the oral community are critical properties in the development of biogeographic differences by their genomes across populations. In this sense, the study of the genomic variation of these commensals across human populations can shed light on the dynamics of the co-evolution between humans and of their commensals. In addition, some of these members are closely related with important human pathogens that show a very efficient and distinct person-to-person transmission. The study of the genetic and phenotypic variation of these oral commensals and of their evolutionary relationships with their pathogenic relatives may then provide important insights into the genetic determinants of different life strategies. The current feasibility in performing whole-genome sequencing of hundreds of bacterial genomes in a single reaction will allow to obtain a significant set of genomic variation for population and phylogenetic/evolutionary analyses at an affordable cost. The aim of this PhD project is to study the transmission, genomic variation and evolution of oral commensals and of their related pathogen species within and among major human populations. To this end, the work will combine microbiological techniques with novel genomics and computational approaches to investigate the patterns of oral bacterial evolution in cohorts from Africa, Europe and Asia.