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<p>Cyanobacterial blooms are becoming more frequent, widespread, and ecologically disruptive, emphasizing the need for effective, species-specific control strategies. This study assessed the short-term physiological and toxin-related responses of bloom-forming cyanobacteria to oxidative stress induced by hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), a commonly proposed mitigation agent. Multiple <i>Raphidiopsis raciborskii</i> strains were compared with <i>Microcystis aeruginosa</i> and <i>Aphanizomenon flos-aquae</i> to evaluate inter- and intraspecific variability in stress tolerance. H<sub>2</sub>O<sub>2</sub> exposure inhibited growth in all species, with <i>Aph. flos-aquae</i> being the most sensitive, toxin-producing strains moderately affected, and a non-toxic <i>R. raciborskii</i> strain showing the highest resistance. <i>Raphidiopsis raciborskii</i> strains exhibited variable PSII responses to H<sub>2</sub>O<sub>2</sub>, ranging from transient impairment with partial recovery to high tolerance with improved efficiency, while <i>Aph. flos-aquae</i> showed sustained damage and <i>M. aeruginosa</i> strains responded from mild stress (NIES-298) to severe and irreversible impairment (PCC 7813). Toxin gene expression revealed transient variability in <i>R. raciborskii cyr</i> genes expression under H<sub>2</sub>O<sub>2</sub> exposure, while <i>M. aeruginosa</i> downregulated <i>mcy</i> genes, suggesting transcriptional control of MC production. The observed reduction in intracellular toxin levels, followed by partial recovery, indicates dynamic metabolic adjustments in response to stress. All the results reveal species- and strain-specific physiological traits and responses to oxidative stress, reflecting complex ecological adaptations shaped by evolutionary pressures. These findings support the need for tailored approaches of bloom management and further research into the molecular background of cyanobacterial resilience.</p> Graphical abstract <p></p>

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Hydrogen peroxide stress in Raphidiopsis raciborskii: strain-specific disruption of photosynthesis and toxin regulation

  • 期刊论文

  • 发表日期：

    2026年3月31日

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  • Tokodi Nada,
  • Antosiak Adam,
  • Drobac Backović Damjana,
  • Willis Anusuya,
  • Kokociński Mikołaj,
  • Svirčev Zorica,
  • Meriluoto Jussi,
  • Dziga Dariusz

摘要

Cyanobacterial blooms are becoming more frequent, widespread, and ecologically disruptive, emphasizing the need for effective, species-specific control strategies. This study assessed the short-term physiological and toxin-related responses of bloom-forming cyanobacteria to oxidative stress induced by hydrogen peroxide (H2O2), a commonly proposed mitigation agent. Multiple Raphidiopsis raciborskii strains were compared with Microcystis aeruginosa and Aphanizomenon flos-aquae to evaluate inter- and intraspecific variability in stress tolerance. H2O2 exposure inhibited growth in all species, with Aph. flos-aquae being the most sensitive, toxin-producing strains moderately affected, and a non-toxic R. raciborskii strain showing the highest resistance. Raphidiopsis raciborskii strains exhibited variable PSII responses to H2O2, ranging from transient impairment with partial recovery to high tolerance with improved efficiency, while Aph. flos-aquae showed sustained damage and M. aeruginosa strains responded from mild stress (NIES-298) to severe and irreversible impairment (PCC 7813). Toxin gene expression revealed transient variability in R. raciborskii cyr genes expression under H2O2 exposure, while M. aeruginosa downregulated mcy genes, suggesting transcriptional control of MC production. The observed reduction in intracellular toxin levels, followed by partial recovery, indicates dynamic metabolic adjustments in response to stress. All the results reveal species- and strain-specific physiological traits and responses to oxidative stress, reflecting complex ecological adaptations shaped by evolutionary pressures. These findings support the need for tailored approaches of bloom management and further research into the molecular background of cyanobacterial resilience.

Graphical abstract