Metagenomic mapping of cyanobacteria and potential cyanotoxin producing taxa in large rivers of the United States

Abstract

Cyanobacteria and cyanotoxin producing cyanobacterial blooms are a trending focus of current research. Many studies focus on bloom events in lentic environments such as lakes or ponds. Comparatively few studies have explored lotic environments and fewer still have examined the cyanobacterial communities and potential cyanotoxin producers during ambient, non-bloom conditions. Here we used a metagenomics-based approach to profile non-bloom microbial communities and cyanobacteria in 12 major U.S. rivers at multiple time points during the summer months of 2019. Our data show that U.S. rivers possess microbial communities that are taxonomically rich, yet largely consistent across geographic location and time. Within these communities, cyanobacteria often comprise significant portions and frequently include multiple species with known cyanotoxin producing strains. We further characterized these potential cyanotoxin producing taxa by deep sequencing amplicons of the microcystin E (mcyE) gene. We found that rivers containing the highest levels of potential cyanotoxin producing cyanobacteria consistently possess taxa with the genetic potential for cyanotoxin production and that, among these taxa, the predominant genus of origin for the mcyE gene is Microcystis. Combined, these data provide a unique perspective on cyanobacteria and potential cyanotoxin producing taxa that exist in large rivers across the U.S. and can be used to better understand the ambient conditions that may precede bloom events in lotic freshwater ecosystems.

Geospatial analysis of cyanobacterial exposure and liver cancer in the contiguous United States

“…These included bodies of water such as Florida’s Lake Okeechobee or Utah’s Great Salt Lake, in which cyanobacterial blooms have been documented 18,19 . Similarly, higher CE was observed across major US rivers, consistent with reports of high levels of cyanobacteria in rivers in the absence of blooms 20 …”

“…[18,19] Similarly, higher CE was observed across major US rivers, consistent with reports of high levels of cyanobacteria in rivers in the absence of blooms. [20]…”

Cyanobacterial Harmful Algal Mats (CyanoHAMs) in tropical rivers of central Mexico and their potential risks through toxin production

“…In the case of benthic mats, the influence of nutrients is more complex due to the diverse biosynthetic capacities of the cyanobacterial species and associated bacteria in the biofilm (Bouma-Gregson et al, 2019 ; Robichon et al, 2023 ). For example, a metagenomic mapping of cyanobacteria mats in large rivers within the United States of America recorded Proteobacteria, followed by Actinobacteria, Bacteroidetes, and Cyanobacteria as the most abundant and frequent bacterial taxa in general (Linz et al, 2023 ). It is possible that the non-cyanobacterial organisms present in the environment influence the production and degradation of cyanotoxins (Bouma-Gregson et al, 2019 ).…”