Amphibian Microbiomes as Indicators of Individual and Environmental Health

Sarah Leyman, The Ohio State University

Cases/Abstracts, Winner

AMPHIBIAN MICROBIOMES AS INDICATORS OF INDIVIDUAL AND ENVIRONMENTAL HEALTH

Sarah Leyman¹, Barbara Wolfe¹, Paula Mouser² 

¹The Ohio State University College of Veterinary Medicine, 1900 Coffey Road, Columbus, OH, USA

²The Ohio State University Department of Civil, Environmental and Geodectic Engineering, 2070 Neil Avenue, Columbus, OH, USA

Amphibians depend on their cutaneous microbial community as a first line of immune defense against disease. However, very few studies have been performed to characterize the bacterial genera found on the skin of different amphibian species and under different water quality conditions.  The goal of this study was to classify the bacterial genera present on the skin of two Lithobates species living in lakes of highly variant water characteristics on a reclaimed surface mine.  A second objective was to develop a baseline frog microbiome library on the site prior to shale gas exploration in order to monitor microbiome changes in association with environmental disturbance. Northern green frogs (Lithobates clamitans melanota) and American bullfrogs (Lithobates catesbeiana) were caught from 10 different lakes on the Wilds in Cumberland, OH.  Skin swabs were collected following a sterile saline solution rinse for bacterial characterization and to test for Batrachochytrium dendrobatiditis (Bd), the etiologic agent of amphibian chytridiomycosis.  Pharyngeal swabs were taken to test for ranavirus, another emerging disease of amphibians, and blood samples were collected to assess the heterophil-lymphocyte ratio as an indicator of stress. Water quality parameters were documented and water samples collected for chemical analysis at the time of frog capture for each site. The DNA was extracted from the bacterial swabs and sequenced using 454 pyro-sequencing.  At least one frog from each site tested was positive for Bd, but no frogs were positive for ranavirus.  Water quality among sites varied with regard to pH (4.10 to 8.66), conductivity (137.5 μS/cm to 3.51 mS/cm), ionic content, and dissolved organic carbon (0.13 mg/L to 11.7 mg/L).  Our study identified over 300 different genera of microbes representing 68 orders present on frogs on this site. Water quality parameters were found to be associated with differential microbial colonization and physiologic parameters.

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Comments

[Jon Leejo]

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