ANALYSIS OF THE SKIN AND GUT MICROBIOMES OF WILD-CAUGHT FISHES FROM LAKE GUNTERSVILLE, ALABAMA  

The bacterial communities that constitute fish microbiomes are now recognized as essential components of host health and defense from invading pathogens.  Therefore, a better understanding of the natural bacterial communities of healthy individuals and how they interact with the host and other environmental factors is of critical importance. For this study, we hope to expand the existing body of research on fish microbiomes to include the skin and gut microbiomes of important freshwater sport fishes. Our objectives were to 1) characterize the gut and skin microbiomes of three common freshwater fishes including two important sport fishes, largemouth bass Micropterus salmoides and bluegill Lepomis macrochirus as well as the more primitive spotted gar Lepisosteus oculatus, 2) compare intra- and interspecies differences in the composition of each microbiome, and 3) identify potential influences of seasonality on core microbial communities. Skin and gut samples were collected in August and November 2014, and May 2015.  All samples were sequenced as paired-end reads of the 16S rRNA gene via the Illumina MiSeq platform. More than 5M reads were analyzed representing 4,130 and 2,744 OTUs from gut and skin samples, respectively. Good's coverage was higher than 98% in all samples. Spotted gar exhibited the most diverse skin microbiome, while largemouth bass was the least diverse species in terms of skin microbiome composition. The highest diversity in the gut microbiome was observed in bluegill; however, the bacterial communities of spotted gar were the most variable across seasons. All microbiomes analyzed significantly differed between fish species. Seasonal changes in bacterial community structures were also observed.