Department of Earth and Environmental Sciences, Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, United States.
James Madison University, Department of Biology, 951 Carrier Dr., Harrisonburg, VA 22807, United States.
Harmful Algae. 2016 Apr;54:4-20. doi: 10.1016/j.hal.2015.12.007.
This review summarizes the present state of knowledge regarding the toxic, bloom-forming cyanobacterium, Microcystis, with a specific focus on its geographic distribution, toxins, genomics, phylogeny, and ecology. A global analysis found documentation suggesting geographic expansion of Microcystis, with recorded blooms in at least 108 countries, 79 of which have also reported the hepatatoxin microcystin. The production of microcystins (originally "Fast-Death Factor") by Microcystis and factors that control synthesis of this toxin are reviewed, as well as the putative ecophysiological roles of this metabolite. Molecular biological analyses have provided significant insight into the ecology and physiology of Microcystis, as well as revealed the highly dynamic, and potentially unstable, nature of its genome. A genetic sequence analysis of 27 Microcystis species, including 15 complete/draft genomes are presented. Using the strictest biological definition of what constitutes a bacterial species, these analyses indicate that all Microcystis species warrant placement into the same species complex since the average nucleotide identity values were above 95%, 16S rRNA nucleotide identity scores exceeded 99%, and DNA-DNA hybridization was consistently greater than 70%. The review further provides evidence from around the globe for the key role that both nitrogen and phosphorus play in controlling Microcystis bloom dynamics, and the effect of elevated temperature on bloom intensification. Finally, highlighted is the ability of Microcystis assemblages to minimize their mortality losses by resisting grazing by zooplankton and bivalves, as well as viral lysis, and discuss factors facilitating assemblage resilience.
本综述总结了关于产毒、形成水华的蓝藻微囊藻的现有知识状况，特别关注其地理分布、毒素、基因组学、系统发育和生态学。全球分析发现，有文献表明微囊藻的地理分布范围正在扩大，至少在 108 个国家有记录的水华，其中 79 个国家也报告了肝毒素微囊藻毒素。本文回顾了微囊藻产生微囊藻毒素（最初称为“快速死亡因子”）的情况，以及控制该毒素合成的因素，以及该代谢物的推测生态生理作用。分子生物学分析为微囊藻的生态学和生理学提供了重要的见解，同时也揭示了其基因组高度动态和潜在不稳定的性质。本文提出了对 27 种微囊藻物种的遗传序列分析，包括 15 种完整/草图基因组。根据构成细菌种的最严格的生物学定义，这些分析表明，所有微囊藻种都应归入同一物种复合体，因为平均核苷酸同一性值均高于 95%，16S rRNA 核苷酸同一性得分超过 99%，且 DNA-DNA 杂交始终大于 70%。综述还进一步提供了来自全球各地的证据，证明氮和磷在控制微囊藻水华动态方面起着关键作用，以及温度升高对水华加剧的影响。最后，强调了微囊藻组合通过抵抗浮游动物和双壳类动物的摄食、病毒裂解来最小化其死亡率损失的能力，并讨论了促进组合弹性的因素。
