The extent and frequency of harmful cyanobacterial blooms are increasing, owing to the climate change caused by global warming, and some harmful filamentous cyanobacteria that were first reported in the tropics are spreading to temperate regions, such as North America, Europe, and Northeast Asia. Although these exotic invasive cyanobacteria have a high toxigenic potential, they are not targeted in management plans in many countries. This study analyzed the occurrence of and potential toxin and off-flavor secondary metabolite production by invasive nostocalean cyanobacteria in the Nakdong River in Korea, which is a temperate region. The occurrence of four species belonging to three genera of cyanobacteria was confirmed in the Nakdong River. The quantities of cyanobacteria in the Nakdong River were mostly low, fewer than 1,000 cells mL⁻¹. Twenty-four strains belonging to four species in three genera of cyanobacteria were isolated from the Nakdong River. Analysis revealed no off-flavor secondary metabolite production by any of the isolates, and those belonging to Cylindrospermopsis raciborskii, Sphaerospermopsis aphanizomenoides, and S. reniformis were identified as nontoxic strains. However, anatoxin-a production was observed in two of the eleven isolates of Cuspidothrix issatschenkoi. Given the sites and the timing of its occurrence, C. issatschenkoi had the highest potential for toxin production among the invasive nostocalean cyanobacteria appearing in the Nakdong River.

由于全球变暖引起的气候变化，有害的蓝藻水华的程度和频率在增加，并且某些在热带地区首次报道的有害的丝状蓝藻水藻正在蔓延到温带地区，例如北美，欧洲和东北亚。尽管这些外来入侵性蓝细菌具有很高的产毒潜力，但在许多国家中，它们并未成为管理计划的目标。这项研究分析了在温带地区的韩国那洞河中，有侵染性念珠菌蓝藻细菌的产生以及潜在的毒素和异味次级代谢产物的产生。在那洞河中确认了属于蓝细菌三个属的四个物种的发生。那空河中的蓝细菌数量很少，少于1,000个细胞毫升^-1。从那东河中分离出蓝细菌三个属中属于四个物种的二十四个菌株。分析显示，任何分离株均未产生异味次级代谢产物，而属于Cylindrospermopsis raciborskii，Sphaerospermopsis aphanizomenoides和S. reniformis的菌株均被鉴定为无毒菌株。然而，在库氏孢子丝藻的十三个分离物中的两个分离物中观察到了毒素A的产生。考虑到发生地点和发生的时间，在那东河中出现的侵袭性卡萨诺蓝细菌中，伊萨梭菌产生毒素的可能性最高。