Introducing an environmental microbiome to axenic Aedes aegypti mosquitoes documents bacterial responses to a blood meal

Axenic Aedes aegypti mosquitoes were colonized with bacteria from an environmental water source to compare the midgut microbiota acquired from the wild to the microbiome of insectary-reared mosquitoes, specifically over the course of blood meal digestion. 16S rRNA gene sequencing revealed that diversity, composition, and community turnover of the midgut microbiomes were distinct between the insectary and environmental groups, with the environmental microbiomes having a greater diversity and larger temporal shifts over the course of the blood meal. Metagenomic prediction from the 16S rRNA gene sequence data pointed to metabolic processes such as vitamin biosynthesis, fatty acid recycling, and fermentation pathways differentiating the functional potential of the two different microbiomes. To further test if we could identify functional traits that distinguished the two microbiomes, we performed a culture-based assay. Culturable bacteria were more abundant in the insectary microbiomes and there was very little overlap in the taxonomy of bacteria recovered from the insectary or environmental groups. The ability of the isolates to lyse blood cells was determined on blood agar plates, and only isolates from the environmental microbiome harbored the ability to perform hemolysis in culture. These data support that the differences in taxonomy observed between the two different microbiomes also result in differences in the functional potential of the community. Thus, this study demonstrates the power of the axenic mosquito model to shed light on the community ecology of the mosquito microbiome, and the potential to better represent the microbiomes of wild mosquitoes in a laboratory setting.