Ecological Dynamics of Broad- and Narrow-Host-Range Viruses Infecting the Bloom-Forming Toxic Cyanobacterium Microcystis aeruginosa

Abstract

The bloom-forming toxic cyanobacterium Microcystis aeruginosa interacts with diverse broad- and narrow-host-range viruses. However, the dynamics of the Microcystis population (at the intraspecies level) and viruses with different host ranges remain unknown.

TrackingMicrocystisviruses and infection dynamics across distinct phases of aMicrocystis-dominated bloom

“…While we have no available methods to determine the true number of uncultivated viruses infecting a given uncultivated host, these numbers of predicted Microcystis viruses are higher than previously reported from metagenomic studies that used other approaches to identify putative Microcystis -infecting viruses. 53,56,66 Given the 87.8% accuracy of VHIP in predicting infections, 3 we are confident that a majority of the co-evolutionary associations identified in these data reflect true virus-host interactions. CRISPR spacer-only infection networks predicted only 16 infections total across two bloom peaks, far fewer than the VHIP network (SI Fig.…”

“…3 A previous study using qPCR to track metagenome-identified viral groups showed how narrow host range Microcystis viruses were observed at markedly lower abundances than broad host range viruses, which tended to be more dominant. 56 We tested whether similar trends were observed in the Lake Erie bloom. The predicted host range depended on whether only Microcystis hosts were considered (as in the Morimoto et al, 2023 study) or all hosts were considered (Fig.…”

“…Our method for predicting bacterial hosts of putative Microcystis viruses overcomes the limitations of marker gene analyses, which have historically been restricted to tracking and linking a single viral population, 39,51,53,66,83,94 and CRISPR-based approaches, 55,56 which are limited by the absence of detectable CRISPR systems in many bacterial genomes. 9 Additionally, our method does not rely on coassociations between viral and Microcystis marker genes, 66 which may oversimplify ecological complexities by assuming binary interactions and linear correlations, when in reality these ecological relationships are varied and rarely linear.…”