A Coupled Assay System for the Lysis of Cyanobacteria.

An assay system was described for studying the mechanism for the lysis of cyanobacteria, which consists of (1) the improved soft-agar overlayer (SAO) method, and (2) the chlorophyll absorbance (CA) method. In the SAO, the activity was observed on a following double-layer agar plate; the agar was covered with a soft agar containing precultured Microcystis aeruginosa in a schale. Lytic plaques on the agar plate were observed using the disk method and/or cup method. In the CA, the cultured cyanobacterium was centrifuged and an aliquot of the concentrated suspension was poured into each well of a 96-well microplate. Subsequently, sample solution was added to the well and the plate was settled. The plates were daily measured for observing any increase or decrease in the OD665. CA has the number of advantages over SAO when considering practical use, however, SAO is indispensable for qualitative analysis, the elucidation of the mode of action and relationship between structure and activity. This method was applied to screen lytic compounds in a lake and two amino acids were found to have lytic activity.