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Assessment of Cyanotoxin Production Potential in Drinking Water Sources under Climate Change

Reservoirs are important drinking water sources in Japan, but harmful algal blooms have become a serious issue in many reservoirs. These blooms occur when cyanobacteria proliferate excessively and cover the water surface in green. They can cause unpleasant taste and odor problems as well as difficulties in water purification processes. In addition, some cyanobacteria are capable of producing toxic substances called cyanotoxins, posing a potential risk to the safety of drinking water sources. Although climate change is expected to increase the frequency and intensity of algal blooms, the environmental conditions under which toxin-producing cyanobacteria become dominant remain unclear. This study focuses not only on the spring and summer seasons, when algal blooms become visible, but also on the overwintering process that precedes bloom formation. By developing toxin-deficient strains using gene-editing technology and comparing them with toxin-producing strains, this study investigates differences in survival and energy allocation under low-temperature and low-light conditions. Furthermore, by combining culture experiments, metabolic analysis, and mathematical modeling, this research aims to evaluate the environmental conditions under which cyanotoxin risks are likely to increase under climate change.

1. A comparative analysis of Landsat-8 and MODIS 1 data for forecasting cyanobacterial blooms in small-scale reservoirs
   Yohei Miura, Yoshiya Touge, Shoya Tanaka, Yoshifumi Masago, Hiroomi Imamoto, Yasuhiro Asada, Michihiro Akiba, Osamu Nishimura, Daisuke Sano
   Remote Sensing Applications: Society and Environment, August 2025, 39, 101672.

1. Effects of cell-to-cell communication molecule concentration on toxin production in Microcystis aeruginosa
   Shoya Tanaka, Yohei Miura, Daisuke Sano
   The 13th International Symposium on Water Environment Systems
   Nov. 14, 2025, Tohoku University, Japan
2. The impact of cell-to-cell signaling molecules on microcystin production
   Shoya Tanaka, Yohei Miura, Daisuke Sano
   10th IWA-ASPIRE Conference and Water New Zealand Conference & Expo
   Sep. 29 – Oct. 3, 2025, Christchurch, New Zealand
3. The impact of climate change on the cyanotoxin production in drinking water sources
   Shoya Tanaka
   The 2nd Symposium for Human and Environmental Security
   Feb. 19, 2025, Tohoku University