Bumble bee gut microbial community structure differs between species and commercial suppliers, but metabolic potential remains largely consistent

Bumble bees are key pollinators for natural and agricultural plant communities. Their health and performance are supported by a core gut microbiota composed of a few bacterial taxa. However, the taxonomic composition and community structure of bumble bee gut microbiotas can vary with bee species, environment, and origin (i.e., whether colonies come from the wild or a commercial rearing facility), and it is unclear whether metabolic capabilities therefore vary as well. Here we used metagenomic sequencing to examine gut microbiota community composition, structure, and metabolic potential across bumble bees from two different commercial <i>Bombus impatiens</i> suppliers, wild <i>B. impatiens</i>, and three other wild bumble bee species sampled from sites within the native range of all four species. We found that the community structure of gut microbiotas varied between bumble bee species, between populations from different origins within species, and between commercial suppliers. Notably, we found that <i>Apibacter</i> is consistently present in some wild bumble bee species-suggesting it may be a previously unrecognized core phylotype of bumble bees-and that commercial <i>B. impatiens</i> colonies can lack core phylotypes consistently found in wild populations. However, despite variation in community structure, the high-level metabolic potential of gut microbiotas was largely consistent across all hosts, including for metabolic capabilities related to host performance, though metabolic activity remains to be investigated.IMPORTANCEOur study is the first to compare genome-level taxonomic structure and metabolic potential of whole bumble bee gut microbiotas between commercial suppliers and between commercial and wild populations. In addition, we profiled the full gut microbiotas of three wild bumble bee species for the first time. Overall, our results provide new insight into bumble bee gut microbiota community structure and function and will help researchers evaluate how well studies conducted in one bumble bee population will translate to other populations and species. Research on taxonomic and metabolic variation in bumble bee gut microbiotas across species and origins is of increasing relevance as we continue to discover new ways that social bee gut microbiotas influence host health, and as some bumble bee species decline in range and abundance.