Effect of Dietary Methylmercury on the Gut Microbiome of Fathead Minnows (Pimephales Promelas)

Purpose: The purpose of this study was to investigate the effect of dietary methylmercury on the gut microbiome of fathead minnows. We hypothesized that consumption of methylmercury would induce a shift in the composition of the gut microbiome. This shift could render the gut susceptible to takeover by opportunistic pathogens. This shift could also increase the concentration of organisms capable of the biotransformation of mercury. Methods: 66 gut samples were obtained from the lab of Dr. Aaron Roberts at the University of North Texas. Methylmercury concentrations ranged from 0.02 to 5.5 parts per million. Bacterial deoxyribonucleic acid (DNA) was extracted, and the sequences for the 16S ribosomal ribonucleic acid (rRNA) were amplified by polymerase chain reaction (PCR). Amplicons were optimized and sequenced using the Ion Torrent™ Personal Genome Machine (PGM™) Sequencer® (Life Technologies™, Carlsbad, CA) with barcoded primers to identify the samples. Sequence data was analyzed using mothur. Results: Data analysis revealed that the presence of dietary methylmercury induced a significant shift in the composition of the microbiome. Communities featured a decrease in order diversity, and an increased concentration of select taxa such as Fusobacteriales. Conclusions: The data supports our hypothesis that exposure to dietary methylmercury induced a shift in the composition of the fathead minnow gut microbiome. Further studies shall be devised to investigate the genome of those select taxa that flourished under these conditions.