Global populations of amphibians are experiencing significant declines due to human induced impacts. Among the most pressing threats are the pathogenic chytrid fungi, Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal). Bd and Bsal infect the skin of a wide range of amphibian taxa and are linked to the decline and extinction of hundreds of species worldwide. The skin of amphibians hosts a diverse community of commensal microorganisms (bacteria, fungi, viruses, etc.) that comprise the skin microbiome. Several bacteria found on the amphibian skin have been shown to inhibit the growth of Bd and Bsal, making them important components of the host microbiome and an extension of the amphibian immune system.

Prior experiments in developing probiotics against chytrid typically utilize cell-free supernatant from isolated bacterial cultures to challenge live Bd or Bsal zoospores. While this has highlighted potentially antagonistic taxa, it removed potential interactions between the amphibian skin microbiome and the pathogen, and limits our capacity to develop effective probiotic therapies to fight these wildlife pathogens. Cerillo’s Co-Culture system will facilitate testing of probiotic consortia by allowing us to more closely simulate conditions found on amphibian skin in nature to better understand the processes and potential applications for probiotics against the disease.

The side-by-side configuration and semipermeable membrane of Cerillo’s co-culture system allows for the exchange of metabolites that affect the development of chytrid zoospores while simultaneously allowing us to measure chytrid growth via spectrophotometer without the influence of the bacteria. Cerillo’s co-culture system will also allow us to better understand the influence of chytrid secondary metabolites on the growth rates of bacteria. Nested trans-well plates have been considered for our past work in this area but are difficult to work with primarily due to them requiring removal of the nested well inserts containing live bacteria to take daily absorbance measurements of the chytrid culture. Each time a nested well is removed, it not only increases the chances for accidental contamination of both cultures, but it greatly slows down the process. The ease of access to each well with Cerillo’s co-culture plates can also facilitate the periodic removal of small volumes of culture for metabolomic and transcriptomic profiling, greatly increasing our knowledge of microbiome-pathogen interactions. Overall, we hope that this system can streamline the testing and selection of amphibian skin probiotics that can be used in developing anti-Bd/Bsal therapies for threatened amphibians.

The ability to co-culture live probiotics and chytrid zoospores will more closely simulate conditions found on amphibian skin in nature to better understand the processes and potential applications for probiotics against the disease.Cerillo’s Co-Culture system will also facilitate testing of probiotic consortia

The ease of access to each well with Cerillo’s co-culture plates can also facilitate periodic removal of small volumes of culture for metabolomic and transcriptomic profiling.