The response of Microcystis aeruginosa strain MGK to a single or two consecutive H₂O₂ applications

Abstract

Summary Various approaches have been proposed to control/eliminate toxic Microcystis sp. blooms including H2O2 treatments. Earlier studies showed that pre‐exposure of various algae to oxidative stress induced massive cell death when cultures were exposed to an additional H2O2 treatment. We examined the vulnerability of exponential and stationary‐phase Microcystis sp. strain MGK cultures to single and double H2O2 applications. Stationary cultures show a much higher ability to decompose H2O2 than younger cultures. Nevertheless, they are more sensitive to an additional H2O2 dose given 1–6 h after the first one. Transcript analyses following H2O2 application showed a fast rise in glutathione peroxidase abundance (227‐fold within an hour) followed by a steep decline thereafter. Other genes potentially engaged in oxidative stress were far less affected. Metabolic‐related genes were downregulated after H2O2 treatments. Among those examined, the transcript level of prk (encoding phosphoribulose kinase) was the slowest to recover in agreement with the decline in photosynthetic rate revealed by fluorescence measurements. Our findings shed light on the response of Microcystis MGK to oxidative stress suggesting that two consecutive H2O2 applications of low concentrations are far more effective in controlling Microcystis sp. population than a single dose of a higher concentration.

Interspecific protection against oxidative stress: green algae protect harmful cyanobacteria against hydrogen peroxide

“…High sensitivity of cyanobacteria to oxidative stress has not only been reported for Prochlorococcus in the oligotrophic ocean but also for freshwater cyanobacteria in eutrophic lakes (Drábková et al ., 2007a; Matthijs et al ., 2012; Barrington et al ., 2013; Lürling et al ., 2014; Weenink et al ., 2015; Daniel et al ., 2019). Some of these cyanobacteria can form dense and often toxic blooms during warm periods in summer, deteriorating water quality with severe negative impacts on drinking water reservoirs, irrigation and recreation (Chorus and Bartram, 1999; Carmichael, 2001; Codd et al ., 2005; O'Neil et al ., 2012; Huisman et al ., 2018).…”

Suppressing Cyanobacteria with Hydrogen Peroxide Is More Effective at High Light Intensities

“…Under high light stress, the chloroplasts of eukaryotic algae produce H 2 O 2 in the Mehler reaction [34,35], whereas cyanobacteria use a different Mehler-like reaction involving flavodiiron proteins, where this reaction does not produce H 2 O 2 [53][54][55][56]. As a consequence, eukaryotic phytoplankton tend to be better defended against low concentrations of H 2 O 2 (1-10 mg/L), whereas cyanobacteria suffer severe oxidative damage under these conditions [27,42,43,57].…”

Cyanobacterial Harmful Algal Blooms in Aquatic Ecosystems: A Comprehensive Outlook on Current and Emerging Mitigation and Control Approaches

“…Another set of experiments showed the following order of sensitivities: Pseudanabaena limnetica > Raphidiopsis curvata > Cylindrospermopsis raciborskii [ 77 ]. Noticeably, the sensitivity to H 2 O 2 is strongly affected by biotic and abiotic conditions such as nutrient status [ 76 ], prior exposure to ROS [ 90 ], and the presence of other organisms that may possess a significant H 2 O 2 detoxification capability [ 78 ]. The cell density and phase of growth are also important biotic factors that affect sensitivity to H 2 O 2 applications [ 90 ].…”

“…Noticeably, the sensitivity to H 2 O 2 is strongly affected by biotic and abiotic conditions such as nutrient status [ 76 ], prior exposure to ROS [ 90 ], and the presence of other organisms that may possess a significant H 2 O 2 detoxification capability [ 78 ]. The cell density and phase of growth are also important biotic factors that affect sensitivity to H 2 O 2 applications [ 90 ]. Stationary cultures have shown a much higher ability to decompose H 2 O 2 than younger cultures, reflecting the induction of genes engaged in antioxidant activities in the former that already experienced an earlier stress [ 90 ].…”

“…The cell density and phase of growth are also important biotic factors that affect sensitivity to H 2 O 2 applications [ 90 ]. Stationary cultures have shown a much higher ability to decompose H 2 O 2 than younger cultures, reflecting the induction of genes engaged in antioxidant activities in the former that already experienced an earlier stress [ 90 ].…”