Fructobacillus in bumblebee microbiome

https://www.mdpi.com/2075-4450/13/1/98 Composition and stability of the gut microbiome are essential to maintaining a bumblebee's immune system and health. While bumblebees are key pollinators in agricultural landscapes, little is known about how gut microbial communities respond to anthropogenic changes. We used commercially produced colonies of buff-tailed bumblebees (Bombus terrestris) placed in three habitats. Whole guts (midgut, hindgut, and rectum) of B. terrestris specimens were dissected from the body and analyzed using 16S phylogenetic community analysis. We observed significantly different bacterial community composition between the agricultural landscapes (apple orchards and oilseed rape (Brassica napus) fields) and forest meadows, whereas differences in gut communities between the orchards and oilseed rape fields were nonsignificant. Bee-specific bacterial genera such as Lactobacillus, Snodgrassella and Gilliamella dominated gut communities of B. terrestris specimens. In contrast, the guts of B. terrestris from forest meadows were dominated by fructose-associated Fructobacillus spp., which may have been the result of high nectar concentrations in cold-climate-associated forest meadow flowers typical of the northernmost range of B. terrestris's distribution. Bacterial communities of workers were the most diverse. At the same time, that of males and young queens were less diverse, possibly reflecting greater exposure to the colony's inner environment compared to the environment outside the colony, as well as bumblebee age. Our results suggest that habitat quality, exposure to environmental microbes, nectar quality and accessibility, and land use significantly affect gut bacterial composition in B. terrestris. This, in turn, may suggest survival and fitness implications for key pollinators.