Termites are amongst the most abundant terrestrial animals on earth largely due to their ability to digest lignocellulose, the most abundant organic molecule on Earth. In the higher termites, lignocellulose is broken down in the gut with the help of symbiotic bacteria. Studies have shown that most termite gut microbes are found nowhere else than in termite guts, and that they are acquired by vertical transfer from parent to offspring, and horizontal transfer between colonies. Up to now, most studies have used 16S rRNA marker to determine the bacterial community composition, preventing any functional analyses. Additionally, most studies focused on distantly related species, preventing any attempt to quantify the contribution of vertical and horizontal transmission to gut microbial communities. To address these questions, I sequenced gut metagenomes of 60 samples, belonging to 37 species, of Microcerotermes collected across four continents. In this talk, I will describe how bacterial communities varies within species, and between closely related species. I will attempt to quantify the proportion of termite gut bacterial communities shaped by vertical and horizontal transmission, and how this affects the functional composition of the gut bacterial communities.