Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea.
Department of Life Science, Chung-Ang University, Seoul, 06974, Republic of Korea.
J Microbiol. 2024 Nov;62(11):933-950. doi: 10.1007/s12275-024-00172-7. Epub 2024 Oct 8.
Many of the world's freshwater ecosystems suffer from cyanobacteria-mediated blooms and their toxins. However, a mechanistic understanding of why and how Microcystis aeruginosa dominates over other freshwater cyanobacteria during warmer summers is lacking. This paper utilizes comparative genomics with other cyanobacteria and literature reviews to predict the gene functions and genomic architectures of M. aeruginosa based on complete genomes. The primary aim is to understand this species' survival and competitive strategies in warmer freshwater environments. M. aeruginosa strains exhibiting a high proportion of insertion sequences (~ 11%) possess genomic structures with low synteny across different strains. This indicates the occurrence of extensive genomic rearrangements and the presence of many possible diverse genotypes that result in greater population heterogeneities than those in other cyanobacteria in order to increase survivability during rapidly changing and threatening environmental challenges. Catalase-less M. aeruginosa strains are even vulnerable to low light intensity in freshwater environments with strong ultraviolet radiation. However, they can continuously grow with the help of various defense genes (e.g., egtBD, cruA, and mysABCD) and associated bacteria. The strong defense strategies against biological threats (e.g., antagonistic bacteria, protozoa, and cyanophages) are attributed to dense exopolysaccharide (EPS)-mediated aggregate formation with efficient buoyancy and the secondary metabolites of M. aeruginosa cells. Our review with extensive genome analysis suggests that the ecological vulnerability of M. aeruginosa cells can be overcome by diverse genotypes, secondary defense metabolites, reinforced EPS, and associated bacteria.
世界上许多淡水生态系统都受到蓝藻介导的水华及其毒素的影响。然而，人们对于为什么以及如何在温暖的夏季，铜绿微囊藻比其他淡水蓝藻占优势缺乏机制上的理解。本文利用比较基因组学和其他蓝藻的文献综述，根据完整基因组预测铜绿微囊藻的基因功能和基因组结构。主要目的是了解该物种在温暖淡水环境中的生存和竞争策略。表现出高比例插入序列（~11%）的铜绿微囊藻菌株具有不同菌株之间低共线性的基因组结构。这表明存在广泛的基因组重排和许多可能的不同基因型，这导致了比其他蓝藻更大的种群异质性，以提高在快速变化和威胁环境挑战下的生存能力。缺乏过氧化氢酶的铜绿微囊藻菌株在具有强烈紫外线辐射的淡水环境中甚至容易受到低光强度的影响。然而，它们可以在各种防御基因（如 egtBD、cruA 和 mysABCD）和相关细菌的帮助下持续生长。铜绿微囊藻细胞对生物威胁（如拮抗细菌、原生动物和噬藻体）具有强大的防御策略，这归因于密集的胞外多糖（EPS）介导的聚集形成，具有有效的浮力和铜绿微囊藻细胞的次生代谢产物。我们的广泛基因组分析表明，通过多种基因型、次生防御代谢物、强化的 EPS 和相关细菌，可以克服铜绿微囊藻细胞的生态脆弱性。
