Sterilization effect of 254 nm UV-C irradiation against cyanobacteriaMicrocystis aeruginosa

摘要

Harmful algal bloom (HAB) produced by several cyanobacterial species is a significant threat to many aquatic ecosystems around the world. Recently frequent occurrence of serious algal bloom in Lake Taihu; Lake Dianchi and Lake Chaohu has become a serious concern in China. Although various methods are currently being used to control toxic blue-green algal water blooms, many of their techniques are of limited use. In this study, the use of 254 nm UV-C radiation to control algal growth was evaluated using Microcystis aeruginosa as test species. The UV-C irradiation of more than 99 |iW cm-2 light intensity was found to be lethal to M. aeruginosa. Under incubated conditions with petri dishes and with 20 hours exposure to the UV-C irradiation of 1370 muWcm~(-2), almost all the cells settled to the bottom of the incubation Petri dishes, whereas all the unirradiated cells remained in suspension. It was also observed by microstructure and ultrastructure slice-ups that the UV-C radiation had a significant kill and wound effect on algal cells and controlled algal growth. After a UV-C dose of no less than 7.2 J cm-2, most algae cells dispersed, whereas all the unirradiated cells remained agglomerative.