(387c) Metagenomic Study of Temporal Changes in Water Microbiomes

Harmful algal blooms (HABs) occur frequently in the summer in the Ohio River. Nutrient pollution has been an increasing issue in the Ohio River watershed. Phosphorus and nitrogen have been the main contributors to the occurrences of algal bloom. River microbial communities and nutrients can fluctuate significantly across time and space. We use shotgun metagenomics to determine the changes in Ohio River microbial communities over a 6-month period. Water physical and chemical properties such as temperature, pH, conductivity, total organic carbon (TOC), phosphate and nitrate concentration were also determined. Shotgun DNA sequencing was carried out using Illumina NextSeq 550 in the Department of Environmental Health (Center for Environmental Genetics) at the University of Cincinnati. The generated fastq.gz data file was analyzed through National Microbiome Data Collaborative (NMDC) EDGE platform. We used three taxonomy classification tools (GOTTCHA2, Kraken2 and Centrifuge) to create microbial community profiles. Taxonomic levels (species, genus, and family) and Krona plot were generated for each tool. Centrifuge generated the highest classified reads (279,856) and species (5,003), while GOTTCHA2 generated the lowest classified reads (29,697) and species (20). We observed substantial temporal variation in the composition of the bacteria communities. The top 5 species changed from Limnohabitans sp., Candidatus Planktophila, C. Methylopumilus, C. Fonsibacter and Homo sapiens in July to C. Planktophila, Limnohabitans sp., Home sapiens and Pseudomonas mandelii in November. The virus counts in the Ohio River increased significantly from July to November. The conductivity of water reached the highest of 461 µS/cm at the end of August, then gradually decreased to 314 µS/cm in November. Phosphate fluctuated from 0.12 to 0.58 mg/L and nitrate changed between 0.04 to 0.18 mg/L. The results showed the dynamic nature of the river microbiomes.