Diversity of 2-MIB-producing cyanobacteria in Lake Ogawara: Microscopic and molecular ecological approaches
2020
Shizuka, K. ((Kitasato University, Towada, Aomori (Japan). Graduate School of Veterinary Science), (Aomori Prefectural Industrial Technology Research Center, Towada, Aomori (Japan). Inland Water Fishery Research Institute)) | Ikenaga, M. | Murase, J. | Nakayama, N. | Matsuya, N. | Kakino, W. | Taruya, H. | Maie, N.
Musty odor owing to 2-methylisoborneol (2-MIB) is a worldwide concern, causing deterioration in the quality of tap water and fish catch. In lakes, a large number of 2-MIB-producing cyanobacteria have been identified to be Pseudanabaena species, but the mechanisms underlying their occurrence have not been revealed. In this study, we investigated the occurrence-related characteristics and taxonomical composition of 2-MIB-producing Pseudanabaena in Lake Ogawara, Aomori Prefecture, Japan, using molecular biology techniques in combination with microscopic observations. In molecular biological analyses, amplicon sequencing and qPCR specific for 2-MIB-producing species were performed. Musty odor-producing Pseudanabaena-like cyanobacteria (MOPPL-cyanobacteria) observed by microscopy mainly occurred during autumn-winter and, to a lesser extent, during spring-summer. There was a positive correlation between the densities of MOPPL-cyanobacteria and 2-MIB-producing strains, but the latter accounted for only 8% of the former, suggesting that a large number of non-MIB-producing strains are included in the microscopy results. At least two 2-MIB-producing Pseudanabaena strains probably exist in Lake Ogawara, and the composition of MOPPL-cyanobacteria is likely to vary at the species/strain level, which cannot be microscopically detected.
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