Molecular and morphological characterization of a novel dihydroanatoxin-a producing Microcoleus species (cyanobacteria) from the Russian River, California, USA

Reports of anatoxin-a poisoning of wildlife and domestic animals by toxigenic cyanobacteria in streams and rivers are increasing globally. Little is known about the taxonomy, morphology and genomics of anatoxin-a producing species, limiting our knowledge about their environmental preferences. We isolated three benthic non-heterocystous filamentous cyanobacterial strains from the Russian River in Northern California (USA), which produce anatoxin-a and dihydroanatoxin-a. Both 16S rRNA and protein sequence phylogenetic analyses showed that the strains represent a distinct new member of the cyanobacterial genus Microcoleus (Oscillatoriales). A novel species, Microcoleus anatoxicus is described and accompanied with light microscope photomicrographs, toxin profiles and the complete anatoxin-a gene cassette with the first description of the anaK gene in Microcoleus.

全球范围内，由产毒蓝细菌（cyanobacteria）在溪流与河流中引发野生生物与家畜感染鱼腥藻毒素a（anatoxin-a）的报道正逐年增多。目前学界对产鱼腥藻毒素a物种的分类学、形态学及基因组学特征尚所知甚少，这限制了我们对其环境偏好的认知。我们从美国北加利福尼亚州的俄罗斯河（Russian River）中分离得到3株底栖、无异囊的丝状蓝细菌菌株，该类菌株可产生鱼腥藻毒素a与双氢鱼腥藻毒素a（dihydroanatoxin-a）。基于16S核糖体RNA（16S rRNA）与蛋白质序列的系统发育分析结果均显示，这些菌株属于蓝细菌微鞘藻属（Microcoleus，颤藻目Oscillatoriales）下一个全新的独立类群。本研究正式描述了一个新物种——产毒微鞘藻（Microcoleus anatoxicus），并附带光学显微镜显微照片、毒素谱信息，以及完整的鱼腥藻毒素a基因盒，同时首次报道了微鞘藻属中anaK基因（anaK gene）的相关特征。