Sensitivity to hydrogen peroxide of the bloom-forming cyanobacterium Microcystis PCC 7806 depends on nutrient availability

• Published in: Harmful algae Vol. 99; p. 101916
• Main Authors: Sandrini, Giovanni, Piel, Tim, Xu, Tianshuo, White, Emily, Qin, Hongjie, Slot, Pieter C., Huisman, Jef, Visser, Petra M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.11.2020
• Subjects: Cyanobacteria; environmental factors; Gene expression; genes; Harmful algal blooms; Hydrogen Peroxide; light intensity; Microcystins; Microcystis; nitrogen; nutrient availability; Nutrient limitation; Nutrients; peroxiredoxin; phosphorus; Photosynthesis; Photosynthetic yield; poisonous algae; thioredoxins; Harmful algal blooms; Photosynthetic yield; Hydrogen peroxide; Nutrient limitation; Gene expression; Microcystis; Microcystins
• ISSN: 1568-9883; 1878-1470; 1878-1470
• DOI: 10.1016/j.hal.2020.101916

•Hydrogen peroxide can suppress cyanobacteria in lakes, but sensitivity varies.•Microcystis is more sensitive to H2O2 under nutrient-replete conditions.•Microcystis is more sensitive to H2O2 at high light than at low light intensities.•Nutrient limitation enhances protection of Microcystis against oxidative stress. Application of low concentrations of hydrogen peroxide (H2O2) is a relatively new and promising method to selectively suppress harmful cyanobacterial blooms, while minimizing effects on eukaryotic organisms. However, it is still unknown how nutrient limitation affects the sensitivity of cyanobacteria to H2O2. In this study, we compare effects of H2O2 on the microcystin-producing cyanobacterium Microcystis PCC 7806 under light-limited but nutrient-replete conditions, nitrogen (N) limitation and phosphorus (P) limitation. Microcystis was first grown in chemostats to acclimate to these different experimental conditions, and subsequently transferred to batch cultures where they were treated with a range of H2O2 concentrations (0-10 mg L−1) while exposed to high light (100 µmol photons m−2 s−1) or low light (15 µmol photons m−2 s−1). Our results show that, at low light, N- and P-limited Microcystis were less sensitive to H2O2 than light-limited but nutrient-replete Microcystis. A significantly higher expression of the genes encoding for anti-oxidative stress enzymes (2-cys-peroxiredoxin, thioredoxin A and type II peroxiredoxin) was observed prior to and after the H2O2 treatment for both N- and P-limited Microcystis, which may explain their increased resistance against H2O2. At high light, Microcystis was more sensitive to H2O2 than at low light, and differences in the decline of the photosynthetic yield between nutrient-replete and nutrient-limited Microcystis exposed to H2O2 were less pronounced. Leakage of microcystin was stronger and faster from nutrient-replete than from N- and P-limited Microcystis. Overall, this study provides insight in the sensitivity of harmful cyanobacteria to H2O2 under various environmental conditions.