Postdoctoral Fellowship: PRFB: The role of symbiotic yeasts in structuring bumble bee nest microbial communities

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2024, Integrative Research Investigating the Rules of Life Governing Interactions Between Genomes, Environment, and Phenotypes. The fellowship supports research and training of the fellow who will contribute to the area of Rules of Life in innovative ways. This research will uncover how healthy microbial communities are maintained within social bee nests.

Social bees live in large groups alongside stored food, making them susceptible to pathogens and food spoilage microbes. To prevent infection, bees may rely on associated yeasts that live within the nest and are known to produce antimicrobial compounds that may help maintain a healthy nest microbiome. This project will investigate how antimicrobial production varies among yeasts and how these compounds impact the growth of detrimental microbes, bee health, and bee behavior.

This research will fill an important gap in the current understanding of these bee-associated yeasts, which remain an understudied portion of the microbiome. The results of this research will contribute to bumble bee conservation strategies by providing greater insight into bee-microbe interactions. This fellowship will additionally support research and teaching training for the fellow as well as the training of multiple undergraduate students.

To determine how symbiotic Starmerella yeasts impact microbial communities of bee nests, this project will first test variations in antimicrobial (sophorolipid) production across yeast strains. Yeasts will be acquired from multiple sources (bees, other insects, and fruit/food spoilage) and cultured in sophorolipid production media. Sophorolipids will then be isolated, quantified, and compared across strains and isolation sources.

The impact of sophorolipids on nest communities and bee health will then be investigated. Yeast strains varying in sophorolipid production will be tested against the bee pathogens Ascosphaera apis and Aspergillus flavus in plate-based inhibition assays. Additionally, synthetic microbial communities of common flower-inhabiting microbes will be grown with and without Starmerella yeasts to determine impacts on community succession.

These treatment communities will be fed to colonies of the bumble bee Bombus impatiens to measure the effects on bee performance. Finally, the impacts of sophorolipids and yeasts on bee feeding and foraging behavior will be tested using CAFÉ assays and y-tube assays, respectively. The volatile compound composition of each yeast and sophorolipid concentration will be measured using GC-MS to determine compounds underlying bee preferences.

This fellowship will support research training for the fellow in multiple new techniques, including GC-MS, volatile compound analysis, and bee behavior assays.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.