Temporal Variation of the Skin Bacterial Community and Infection in the Terrestrial Cryptic Frog .

In animals and plants, symbiotic bacteria can play an important role in disease resistance of host and are the focus of much current research. Globally, amphibian population declines and extinctions have occurred due to chytridiomycosis, a skin disease caused by the pathogen (Bd). Currently amphibian skin bacteria are increasingly recognized as important symbiont communities with a relevant role in the defense against pathogens, as some bacteria can inhibit the growth of . This study aims to document the infection status of wild populations of a terrestrial cryptic frog (), and to determine whether infection status is correlated with changes in the skin microbial communities. Skin samples of were collected along an altitudinal range within the species distribution in subtropical rainforests in southeast Australia. Sampling was conducted in two years during two breeding seasons with the first classified as a "La Niña" year. We used Taqman real-time PCR to determine infection status and 16S amplicon sequencing techniques to describe the skin community structure. We found -positive frogs only in the second sampling year with low infection intensities, and no correlation between infection status and altitude, frog sex or size. Skin bacterial diversity was significantly higher in frogs sampled in the 1st year than in the 2nd year. In addition, 7.4% of the total OTUs were significantly more abundant in the 1st year compared to the 2nd year. We identified 67 bacterial OTUs with a significant positive correlation between infection intensity and an OTU's relative abundance. Forty-five percent of these OTUs belonged to the family Enterobacteriaceae. Overall, temporal variation was strongly associated with changes in infection status and bacterial community structure of wild populations of .