Testing probiotic cocktails in Colorado Boreal Toads. Probiotic Cocktails in CO Boreal Toads

Fungal emerging infectious diseases (EID’s), like Batrachochytrium dendrobatidis (Bd) in amphibians, have caused major losses in biodiversity globally. These wildlife diseases are difficult to manage, but one promising treatment is using bioaugmentation of beneficial host microbes. In amphibians, this has mostly focused on Janthinobacterium lividum strains, usually in single-strain amendments, because they are well-characterized in terms of their mechanism of anti-Bd activity and indirect host health effects. There are many other microbes, however, that inhibit Bd in vitro and not all amphibian species see consistent or effective results with J. lividum. We used a series of in vitro assays with Bd lawns on agar plates, bacterial growth, and bacterial cell-free supernatant (CFS) to determine if: (1) other skin microbiota on a locally endangered amphibian, the Colorado boreal toad (Anaxyrus boreas boreas), could be more inhibitive of Bd, (2) whether multi-strain combinations are more effective than single-strain ones, and (3) what implications these microbe-microbe interactions have on applying probiotics to an existing microbiome. Our results indicate that there are some single- and multi-strain probiotics (especially including Pseudomonas sp., Chryseobacterium sp., and Microbacterium sp.) that could work better than J. lividum alone in boreal toads, and that some combinations could lead to loss of inhibition through antagonistic metabolite effects. This highlights the importance of considering the starting microbiota of the host, as well as the fact that every host and abiotic system requires individual evaluation when choosing a probiotic (that is, one size does not fit all when choosing probiotic management strategies against a global fungal EID).