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.

低浓度的过氧化氢（H ₂ O ₂）的应用是一种相对较新的有前途的方法，可以选择性地抑制有害的蓝藻水华，同时将对真核生物的影响降至最低。然而，营养限制如何影响蓝细菌对H ₂ O ₂的敏感性仍然是未知的。在这项研究中，我们比较了H ₂ O ₂在光受限但养分充足的条件下，氮（N）限制和磷（P）限制下，对微囊藻毒素生产的蓝藻微囊藻PCC 7806的影响。微囊藻首先在恒化器中生长以适应这些不同的实验条件，然后转移到分批培养物中，在一定的H ₂ O ₂浓度（0-10 mg L ^-1）下对其进行处理，同时将其暴露在高光（100 µmol光子）下m ^-2 s ^-1）或弱光（15 µmol光子m ^-2 s ^-1）。我们的结果表明，在弱光条件下，N和P限制的微囊藻对H ₂ O _2的敏感度要比光限制但营养丰富的微囊藻。在H ₂ O ₂处理N和P受限的微囊藻之前和之后，观察到抗氧化应激酶（2-cys-peroxiredoxin，thioredoxin A和II型peroxiredoxin）编码基因的表达明显较高，这可以解释它们对H ₂ O ₂的增加的抵抗力。在高光下，微囊藻对H ₂ O _2的敏感度要比低光下高；在暴露于H ₂ O _2的养分充足和营养有限的微囊藻之间，光合产量下降的差异也不同。不太明显。营养丰富的微囊藻毒素的泄漏比N限制和P限制的微囊藻更强，更快。总的来说，这项研究提供了在各种环境条件下有害蓝细菌对H ₂ O ₂的敏感性的见解。