Ubiquity and diversity of Basidiobolus across amphibian species inhabiting an urbanization gradient

The role of microfungal species in the environment is wide and well documented, especially in terms of symbiosis. Nonetheless, microfungal species are usually overseen and vastly understudied. One example of these understudied microfungal groups is the genus Basidiobolus, an ecologically diverse zoopagomycete genus found within vertebrate gastrointestinal systems, a saprobe across leaf litter, or as an opportunistic pathogen of immunocompromised humans. Studies of Basidiobolus diversity and distribution have been focused mostly on non-urbanized areas of subtropical regions, but there is a recent paucity of studies on this genus in temperate and densely human populated areas. Here, we present insights into the ubiquity and diversity of Basidiobolus species associated with amphibian species that live in the Worcester waterway system, a system of connecting streams and ponds that originate in pristine, protected wild management areas, and the highly urbanized downtown area of Worcester, Massachusetts. Our results show the ubiquitous presence of Basidiobolus across the gastrointestinal tract samples of amphibians spanning diverse species and habitats, including conservation areas, urban watersheds, and rural ecosystems. Our study reveals that multiple individuals and species of Basidiobolus coexist within a single host, suggesting complex interactions within amphibian gut microbiomes. Finally, we present possible novel diversity in the genus, indicating that further studies should be focused on understanding the species richness, genetic diversity, and ecological roles and associations of this interesting fungal group.