Microcystis aeruginosa, an important cyanobloom-forming cyanobacterium, is sensitive to the high light intensity and consequent oxidative stress. Based on our genomic and transcriptomic analyses of H₂O₂-treated cells, many genes involved in photosynthesis, Calvin cycle, and microcystin synthesis were downregulated, whereas several toxin-antitoxin genes, DNA repair genes, and H₂O₂-defense systems such as peroxiredoxins and glutathione synthesis were upregulated. Axenic M. aeruginosa was then co-cultured with synthetic bacterial communities collected from 15 different freshwater samples with exhibiting different degrees of H₂O₂-production and catalase activities. Our analyses indicated that H₂O₂-resistant bacterial communities favored the growth and photosynthetic activity of M. aeruginosa cells under either H₂O₂ treatment or high light conditions. Nanopore-based bacterial community analyses indicated that these growth-promoting effects were likely attributable to a high proportion of Alphaproteobacteria (e.g., Brevundimonas and Ochrobactrum species), which protected M. aeruginosa cells from H₂O₂ toxicity. Further, these bacterial communities exhibited higher catalase activity levels and faster O₂ production rates upon H₂O₂ detoxification. Taken together, our findings newly suggest that the occurrence of catalase-less M. aeruginosa blooms is largely influenced by the surrounding microbiota during high light and organic-rich conditions.

铜绿微囊藻是一种重要的蓝藻形成蓝藻，对高光强度和随之而来的氧化应激敏感。根据我们对 H ₂ O ₂处理细胞的基因组和转录组分析，许多参与光合作用、卡尔文循环和微囊藻毒素合成的基因被下调，而一些毒素抗毒素基因、DNA 修复基因和 H ₂ O ₂防御系统如过氧还蛋白和谷胱甘肽的合成被上调。无菌铜绿微囊藻然后用来自15克不同的样品淡水收集与表现出不同程度的h的合成细菌群落共培养₂ ö ₂-生产和过氧化氢酶活动。我们的分析表明，在 H ₂ O ₂处理或强光条件下，H ₂ O ₂抗性细菌群落有利于M. aeruginosa细胞的生长和光合活性。基于纳米孔的细菌群落分析表明，这些促进生长的作用可能归因于高比例的Alphaproteobacteria（例如Brevundimonas和Ochrobactrum物种），它们保护M. aeruginosa细胞免受 H ₂ O ₂毒性。此外，这些细菌群落在 H ₂ O ₂解毒后表现出更高的过氧化氢酶活性水平和更快的 O ₂生产率。总之，我们的研究结果新表明，在高光和富含有机物的条件下，无过氧化氢酶的铜绿假单胞菌大量繁殖在很大程度上受周围微生物群的影响。