Gregory J. Dick: The role of hydrogen peroxide in toxicity of cyanobacterial blooms

The role of hydrogen peroxide in toxicity of cyanobacterial blooms

The eutrophication of lakes, reservoirs and rivers worldwide has led to the proliferation of toxic cyanobacterial blooms that threaten freshwater ecosystems, drinking supplies, and human health.  Despite rapid progress in understanding the biosynthetic and genetic pathways for these cyanobacterial toxins, the ecological and environmental drivers of toxicity remain unclear.

Recent research suggests that the physiological purpose of the microcystin, a cyanotoxin produced by the globally distributed cyanobacterium Microcystis aeruginosa, is to protect cyanobacterial cells from oxidative stress.  This seminar will focus on studies of the interplay between Microcystis and hydrogen peroxide in the western basin of Lake Erie, USA, where Microcystis blooms occur on a massive scale annually.  We find that hydrogen peroxide in surface waters reaches high concentrations, sufficiently high to effect cyanobacterial fitness, during bloom development due to biological production.

This environmental hydrogen peroxide is this rapidly decomposed by heterotrophic bacteria associated with the bloom, suggesting important interactions between cyanobacteria and associated bacteria.

This seminar will describe our efforts to disentangle the sources and sinks of H₂O₂ in cyanobacterial blooms and its effect on cyanobacterial community composition and function.