Microcystis spp., notorious bloom-forming cyanobacteria, are often present in colony form in eutrophic lakes worldwide. Uncovering the mechanisms underlying Microcystis colony formation and maintenance is vital to controlling the blooms, but it has long been a challenge. Here, bacterial communities and gene expression patterns of colonial and unicellular forms of one non-axenic strain of Microcystis aeruginosa isolated from Lake Taihu were compared. Evidently, different microbial communities between them were observed through 16S rDNA MiSeq sequencing. Metatranscriptome analyses revealed that transcripts for pathways involved in bacterial biofilm formation, such as biosynthesis of peptidoglycan and arginine by Bacteroidetes, methionine biosynthesis, alginate metabolism, flagellum, and motility, as well as widespread colonization islands by Proteobacteria, were highly enriched in the colonial form. Furthermore, transcripts for nitrogen fixation and denitrification pathways by Proteobacteria that usually occur in biofilms were significantly enriched in the colonial Microcystis. Results revealed that microbes associated with Microcystis colonies play important roles through regulation of biofilm-related genes in colony formation and maintenance. Moreover, Microcystis colony represents a potential ‘buoyant particulate biofilm’, which is a good model for biofilm studies. The biofilm features of colonial Microcystis throw a new light on management and control of the ubiquitous blooms in eutrophic waters.

中文翻译：

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菌群铜绿微囊藻微生物群落中的基因表达——一种潜在的浮力颗粒生物膜

微囊藻属，臭名昭著的形成水华的蓝藻，通常以菌落形式存在于世界各地的富营养化湖泊中。揭示微囊藻菌落形成和维持的机制对于控制水华至关重要，但这一直是一个挑战。在这里，比较了从太湖中分离出的一种非无菌铜绿微囊藻菌株的菌落和单细胞形式的细菌群落和基因表达模式。显然，通过 16S rDNA MiSeq 测序观察到它们之间的不同微生物群落。元转录组分析揭示了参与细菌生物膜形成的途径的转录物，例如拟杆菌生物合成肽聚糖和精氨酸、蛋氨酸生物合成、藻酸盐代谢、鞭毛和运动，以及变形杆菌广泛的定殖岛，在菌落形式中高度富集。此外，通常发生在生物膜中的变形菌的固氮和反硝化途径的转录物在菌落微囊藻中显着富集。结果表明，与微囊藻菌落相关的微生物通过调节生物膜相关基因在菌落形成和维持中发挥重要作用。此外，微囊藻菌落代表了一种潜在的“浮力颗粒生物膜”，是生物膜研究的良好模型。殖民地微囊藻的生物膜特征为富营养化水域中普遍存在的水华的管理和控制提供新的视角。