Oomycetes are widely distributed in various environments, including desert and polar regions. Depending upon different habits and hosts, they have evolved with both saprophytic and pathogenic nutritional modes. Freshwater ecosystem is one of the most important habitats for members of oomycetes. Most studies on oomycete diversity, however, have been biased mostly towards terrestrial phytopathogenic species, rather than aquatic species, although their roles as saprophytes and parasites are essential for freshwater ecosystems. In this study, we isolated oomycete strains from soil sediment, algae, and decaying plant debris in freshwater streams of Korea. The strains were identified based on cultural and morphological characteristics, as well as molecular phylogenetic analyses of ITS rDNA, cox1, and cox2 mtDNA sequences. As a result, we discovered eight oomycete species previously unknown in Korea, namely Phytopythium chamaehyphon, Phytopythium litorale, Phytopythium vexans, Pythium diclinum, Pythium heterothallicum, Pythium inflatum, Pythium intermedium, and Pythium oopapillum. Diversity and ecology of freshwater oomycetes in Korea are poorly understood. This study could contribute to understand their distribution and ecological function in freshwater ecosystem.

卵菌纲广泛分布在各种环境中，包括沙漠和极地地区。根据不同的习性和宿主，它们具有腐生和致病性营养模式。淡水生态系统是卵菌纲成员最重要的栖息地之一。然而，大多数关于卵菌多样性的研究大多偏向于陆生植物致病物种，而不是水生物种，尽管它们作为腐生植物和寄生生物的作用对于淡水生态系统至关重要。在这项研究中，我们从韩国淡水流中的土壤沉积物，藻类和腐烂的植物残渣中分离了卵菌菌株。根据文化和形态特征，以及ITS rDNA，cox 1和cox 2 mtDNA序列。其结果是，我们中发现8个卵菌物种以前在韩国未知，即Phytopythium chamaehyphon，Phytopythium litorale，Phytopythium刺扰伊蚊，腐霉diclinum，腐霉heterothallicum，肿囊腐霉菌，腐霉媒介和腐霉oopapillum。人们对韩国淡水卵菌的多样性和生态学知之甚少。这项研究可能有助于了解它们在淡水生态系统中的分布和生态功能。