Harmful cyanobacteria producing toxic microcystins are a major concern in water quality management. In recent years, hydrogen peroxide (H₂O₂) has been successfully applied to suppress cyanobacterial blooms in lakes. Physiological studies, however, indicate that microcystin protects cyanobacteria against oxidative stress, suggesting that H₂O₂ addition might provide a selective advantage for microcystin-producing (toxic) strains. This study compares the response of a toxic Microcystis strain, its non-toxic mutant, and a naturally non-toxic Microcystis strain to H₂O₂ addition representative of lake treatments. All three strains initially ceased growth upon H₂O₂ addition. Contrary to expectation, the non-toxic strain and non-toxic mutant rapidly degraded the added H₂O₂ and subsequently recovered, whereas the toxic strain did not degrade H₂O₂ and did not recover. Experimental catalase addition enabled recovery of the toxic strain, demonstrating that rapid H₂O₂ degradation is indeed essential for cyanobacterial survival. Interestingly, prior to H₂O₂ addition, gene expression of a thioredoxin and peroxiredoxin was much lower in the toxic strain than in its non-toxic mutant. Thioredoxin and peroxiredoxin are both involved in H₂O₂ degradation, and microcystin may potentially suppress their activity. These results show that microcystin-producing strains are less prepared for high levels of oxidative stress, and are therefore hit harder by H₂O₂ addition than non-toxic strains.

有害蓝藻产生有毒微囊藻毒素是水质管理中的主要问题。近年来，过氧化氢（H ₂ O ₂）已成功地用于抑制湖泊中的蓝细菌水华。然而，生理学研究表明，微囊藻毒素可保护蓝细菌免受氧化应激的影响，这表明添加H ₂ O ₂可能为产生微囊藻毒素（有毒）的菌株提供选择性优势。这项研究比较了有毒微囊藻菌株，其无毒突变体和天然无毒微囊藻菌株对H ₂ O ₂的响应。除了代表湖泊治疗。当添加H ₂ O ₂时，所有三种菌株最初都停止生长。与预期相反，无毒菌株和无毒突变体迅速降解添加的H ₂ O ₂并随后回收，而有毒菌株没有降解H ₂ O ₂且没有回收。实验性过氧化氢酶的添加使毒性菌株得以恢复，表明快速的H ₂ O ₂降解确实对于蓝细菌的生存至关重要。有趣的是，在H ₂ O _2之前此外，在有毒菌株中，硫氧还蛋白和过氧化物酶的基因表达要比无毒突变体低得多。硫氧还蛋白和过氧化物酶都与H ₂ O ₂降解有关，微囊藻毒素可能会抑制其活性。这些结果表明，产生微囊藻毒素的菌株对于高水平的氧化应激的准备较差，因此与无毒菌株相比，H ₂ O _2的添加对其造成的打击更大。