Inhibition of the harmful alga Microcystis aeruginosa by sugi ( Cryptomeria japonica ) bark

To utilize woody waste for the inhibition of harmful algae, we examined the growth inhibitory activities of sugi ( Cryptomeria japonica ) bark powder against Microcystis aeruginosa , which is a cyanobacteria species that causes algal blooms in lake or pond areas. The growth of M. aeruginosa was inhibited by the direct mixing of sugi bark powder into media in flasks. The inhibitory activity against M. aeruginosa was decreased when the bark underwent organic solvent extractions. Thus, the inhibitory activity was promoted by the extract components. After solvent extraction, the bark maintained a level of inhibitory activity suggestive of both chemical and physical effects. These results show that the growth of M. aeruginosa can be suppressed by directly using sugi bark with no extraction treatment.