Pseudanabaena foetida sp. nov. and P. subfoetida sp. nov. (Cyanophyta/ Cyanobacteria) producing 2-methylisoborneol from Japan

Nasty smell of tap water supplied from Lake Biwa caused a great trouble. Then many researches have been conducted from the point of view of water supply management or water quality in Japan. The matter of this bad smell was identified as 2-methylisoborneol (2-MIB) and the source organism of this bad odor was then reported as Phormidium tenue and later two different cultured strains were established. One of these strains shows green color, produce 2-MIB, and is marked PTG. The other shows brown color, does not produce 2-MIB and is marked PTB. However their nomenclatural description has not been done yet and, in fact, they have morphological characters of genus Pseudanabaena rather than Phormidium. Pseudanabaena species are also observed in Lake Kasumigaura. PS1306 produces 2-MIB and other strain PS1303 has no smell. This study focuses on morphological and genetical (16S rRNA) comparison of strains from both lakes. In addition, the ultrastructure of cells of PTB and PTG are demonstrated. On the basis of this comparison we propose description of two new planktic species producing 2-MIB: Pseudanabaena foetida Niiyama, Tuji et Ichise sp. nov. and P. subfoetida Niiyama et Tuji sp. nov.