Relationship between unicellular cyanobacteria established by indirect immunofluorescence of intact cells

Antisera prepared against intact, viable cells were used to show the applicability of a serological approach to detect relationships between unicellular cyanobacteria. Antisera were raised against eight unicellular cyanobacteria and two chlorophycean unicellular organisms. The staining reactivity of each antiserum was tested by the fixed indirect immunofluorescence assay against the different organisms, and each organism was tested for its reactivity with all of the different antisera. Absorption of antisera with the appropriate heterologous antigens was used to further characterize the relationship betweenAnacystis nidulans andSynechococcus cedrorum, and also the relationship between two subcultures of an isolate distinguished by morphological features. Absorption of antiserum was also used for the removal of antibodies to contaminating bacteria. The approaches used are suggested as a useful tool for determining relationships between unicellular cyanobacteria.