Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea.
Department of Food Science and Biotechnology, CHA University, Pocheon, Gyeonggi-do 11160, Republic of Korea.
Water Res. 2021 Dec 1;207:117784. doi: 10.1016/j.watres.2021.117784. Epub 2021 Oct 26.
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 HO-treated cells, many genes involved in photosynthesis, Calvin cycle, and microcystin synthesis were downregulated, whereas several toxin-antitoxin genes, DNA repair genes, and HO-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 HO-production and catalase activities. Our analyses indicated that HO-resistant bacterial communities favored the growth and photosynthetic activity of M. aeruginosa cells under either HO 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 HO toxicity. Further, these bacterial communities exhibited higher catalase activity levels and faster O production rates upon HO 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形成蓝藻水华的蓝藻，对高光强和由此产生的氧化应激敏感。基于我们对 HO 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合成的基因下调，而一些毒素-抗毒素基因、DNA 修复基因和 HO 防御系统如过氧化物酶和谷胱甘肽合成上调。然后，将铜绿微囊藻与从 15 个不同淡水样本中收集的合成细菌群落进行共培养，这些样本表现出不同程度的 HO 产生和过氧化氢酶活性。我们的分析表明，在 HO 处理或高光条件下，抗 HO 的细菌群落有利于铜绿微囊藻细胞的生长和光合作用活性。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较高比例的α变形菌（例如，短小杆菌和鞘氨醇单胞菌属物种），它们保护铜绿微囊藻细胞免受 HO 毒性的影响。此外，这些细菌群落在 HO 解毒时表现出更高的过氧化氢酶活性水平和更快的 O2 产生速率。总之，我们的研究结果表明，在高光和富有机条件下，缺乏过氧化氢酶的铜绿微囊藻水华的发生在很大程度上受周围微生物群的影响。
