Microcystins (MCs) are secondary metabolites produced by cyanobacteria and have been well-documented in temperate and tropical regions. However, knowledge of the production of MCs in extremely cold environments is still in its infancy. Recently, examination of 100-year-old Antarctic cyanobacterial mats collected from Ross Island and the McMurdo Ice Shelf during Captain R.F. Scott's Discovery Expedition revealed that the presence of MCs in Antarctica is not a new phenomenon. Here, morphological and molecular phylogenetic analyses are used to identify a new microcystin-producing freshwater cyanobacterium, Anagnostidinema pseudacutissimum. The strain was isolated from a deep-frozen (−15 °C) sample collected from a red-brown cyanobacterial mat in a frozen pond at Cape Crozier (Ross Island, continental Antarctica) in 1984–1985. Amplification of the mcyE gene fragment involved in microcystin biosynthesis from A. pseudacutissimum confirmed that it is identical to the sequence from other known microcystin-producing cyanobacteria. Analysis of extracts from this A. pseudacutissimum strain by HPLC-MS/MS confirmed the presence of MC-LR and -YR at concentrations of 0.60 μg/L and MC-RR at concentrations of 0.20 μg/L. This is the first report of microcystin production from a species of Anagnostidinema from Antarctica.

微囊藻毒素（MCs）是蓝细菌产生的次生代谢产物，在温带和热带地区已有大量文献记载。但是，有关在极冷环境中生产MC的知识仍处于起步阶段。最近，在RF Scott上尉的探索探险队期间，对从罗斯岛和麦克默多冰架上收集的100年历史的南极蓝藻垫进行了检查，结果表明，南极洲中不存在MC。在这里，形态学和分子系统发育分析被用来识别一种新的产生微囊藻毒素的淡水蓝细菌，Anagnostidinema pseudacutissimum。该菌株是在1984-1985年从Crozier角（南极洲罗斯岛的一个冷冻池塘）的红棕色蓝​​藻垫中收集的深冷冻（−15°C）样品中分离的。所述的放大mcyE从参与生物合成的微囊藻毒素基因片段A. pseudacutissimum证实，它是与从其它已知的微囊制备蓝藻序列。通过HPLC-MS / MS分析该假单胞菌菌株的提取物，证实存在浓度为0.60μg/ L的MC-LR和-YR以及浓度为0.20μg/ L的MC-RR。这是来自南极的一种Anagnostidinema的微囊藻毒素生产的首次报道。