Enzymatic biosynthesis of B-complex vitamins is supplied by diverse microbiota in the Rhodnius prolixus anterior midgut following Trypanosoma cruzi infection

Trypanosoma cruzi, the causative agent of Chagas disease, colonizes the gut of triatomine insects, including Rhodnius prolixus. It is believed that this colonization upsets the microbiota that are normally present, presumably switching the environment to one more favorable for parasite survival. It was previously thought that one particular bacterium, Rhodococcus rhodnii, was essential for insect survival due to its ability to produce vital B-complex vitamins. However, these bacteria are not always identified in great abundance in studies on R. prolixus microbiota. Here we sequenced the microbiota of the insect anterior midgut using shotgun metagenomic sequencing in order to obtain a high-resolution snapshot of the microbes inside at two different time points and under two conditions; in the presence or absence of parasite and immediately following infection, or three days post-infection. We identify a total of 217 metagenomic bins, and recovered one metagenome-assembled genome, which we placed in the genus Dickeya. We show that, despite Rhodococcus being present, it is not the only microbe capable of synthesizing B-complex vitamins, with the genes required for biosynthesis present in a number of different microbes. This work helps to gain a new insight into the microbial ecology of R. prolixus.