Electron Microscopic Study on Lysis of a Cyanobacterium Microcystis

In a previous study, it was suggested that beta-cyclocitral plays an important role in understanding the lysis of cyanobacteria under natural conditions. The present study was conducted in order to understand how the beta-cyclocitral lyses cyanobacterial cells, and other anti cyanobacterial agents were also investigated. The preliminary study using a scanning electron microscope (SEM) demonstrated that there were three types of morphological changes in the cyanobacterial cells when they were incubated with anticyanobacterial agents: volatile compounds from cyanobacteria cause shrinking and then wrinkling, terpenoids contact directly and cause stripping; basic amino acids cause swelling and then collapsing. In order to clarify the extreme difference in the damage during the morphological changes between the beta-cyclocitral and L-lysine (Lys), the transmission electron microscope (TEM) technique was applied. Although a definite difference in the morphological damage was observed, a plausible mechanism for beta-cyclocitral could be not deduced. Throughout the experiments using antibiotics, it was found that the apparent morphological changes after lysis did not always correspond to the mode of action.