Siddiquee Mashuk, Cornelius Sara, Seo Youngwoo, Bullerjahn George S, Bridgeman Thomas B, Sudman Mike, Kang Dae-Wook
Department of Civil and Environmental Engineering, The University of Toledo, OH, 43606, USA.
Department of Civil and Environmental Engineering, The University of Toledo, OH, 43606, USA; Department of Chemical Engineering, The University of Toledo, OH, 43606, USA.
Water Res. 2025 Sep 1;283:123683. doi: 10.1016/j.watres.2025.123683. Epub 2025 Apr 28.
Cyanobacterial harmful algal blooms pose significant threats to global water supplies, ecosystems, and economies. Among the harmful cyanobacteria, Planktothrix, a resilient and toxin-producing filamentous cyanobacterium, has garnered increasing attention. However, an understanding of the entire microbiome, particularly the phycosphere surrounding Planktothrix blooms, remains largely unexplored. To the best of our knowledge, this is the first comprehensive study combining 16S rDNA and fungal internal transcribed spacer amplicon sequencing and shotgun metagenomics to elucidate Planktothrix bloom microbiomes and identify potential microbial or functional biomarkers for CyanoHABs. Our observations revealed that a summer bloom in Grand Lake St. Marys was initiated with Dolichospermum and then shifted to Planktothrix dominance. This transition was associated with nitrogen metabolism genes, suggesting that nitrogen plays a key role in bloom persistence through interactions among nitrogen-fixing bacteria, ammonia-oxidizing archaea, anammox bacteria, and denitrifiers. Additionally, metagenomic data revealed a strong positive correlation of toxin concentration with carbohydrate-nitrogen-sulfur-fatty acid associated metabolic pathways and a strong negative correlation with pollutant degradation pathways. Intriguingly, diazotrophic methane-related microbes were detected, which opens discussion on potential symbiosis that couples nitrogen and carbon metabolism. Toxin-degrading bacteria, such as Polynucleobacter and Acidovorax, were positively correlated with fungi like Vishniacozyma, proposing their cooperative roles during bloom events. Notably, Rhodobacter, a photosynthetic purple non-sulfur bacterium, showed strong negative correlations with both Planktothrix and the toxin-producing gene mcyE, positioning it as a promising biomarker for early bloom detection. Overall, this study advances the understanding of Planktothrix-dominated bloom ecology and highlights microbial signatures for proactive CyanoHAB management in freshwater systems.
蓝藻有害藻华对全球供水、生态系统和经济构成重大威胁。在有害蓝藻中，浮游丝藻是一种具有韧性且能产生毒素的丝状蓝藻，已受到越来越多的关注。然而，对于整个微生物群落，尤其是浮游丝藻藻华周围的藻际环境，人们仍知之甚少。据我们所知，这是第一项综合运用16S rDNA和真菌内部转录间隔区扩增子测序以及鸟枪法宏基因组学来阐明浮游丝藻藻华微生物群落，并识别蓝藻有害藻华潜在微生物或功能生物标志物的研究。我们的观察结果显示，圣玛丽斯大湖的夏季藻华始于Dolichospermum，随后转变为浮游丝藻占主导地位。这种转变与氮代谢基因有关，表明氮通过固氮细菌、氨氧化古菌、厌氧氨氧化细菌和反硝化细菌之间的相互作用，在藻华持续存在中起着关键作用。此外，宏基因组数据显示毒素浓度与碳水化合物 - 氮 - 硫 - 脂肪酸相关代谢途径呈强正相关，与污染物降解途径呈强负相关。有趣的是，检测到了与固氮甲烷相关的微生物，这引发了关于氮和碳代谢耦合潜在共生关系的讨论。毒素降解细菌，如多核杆菌属和嗜酸菌属，与维斯尼亚酵母属等真菌呈正相关，表明它们在藻华事件中具有协同作用。值得注意的是，光合紫色非硫细菌红杆菌与浮游丝藻和产毒素基因mcyE均呈强负相关，使其成为藻华早期检测的有前景的生物标志物。总体而言，这项研究推进了对浮游丝藻主导的藻华生态学的理解，并突出了微生物特征，以实现淡水系统中蓝藻有害藻华的主动管理。
