GENETIC-CHARACTERIZATION OF STRAINS OF CYANOBACTERIA USING PCR-RFLP OF THE CPCBA INTERGENIC SPACER AND FLANKING REGIONS

Oligonucleotide primers, specific for conserved regions of the genes e ncoding the beta- and alpha-phycocyanin subunits of phycobilisomes (cp cB and cpcA) of cyanobacteria, were used to amplify a DNA fragment con taining the intervening intergenic spacer region (cpcBA-IGS) of 29 str ains of three morphospecies of cyanobacteria. Six Australian strains w ere identified as Anabaena circinalis Rabenhorst, six strains were ide ntified as Microcystis aeruginosa Kutzing, and seven strains were iden tified as Nodularia spumigena Mertens. Restriction enzyme digestion of the amplification products from the strains revealed restriction frag ment length polymorphism (RFLP) within all three morphospecies. Strain s corresponding to M. aeruginosa were highly polymorphic: 11 of the 14 restriction enzymes used displayed RFLPs. The A. circinalis and N. sp umigena strains were less variable: three of 14 enzymes and seven of 1 4 enzymes, respectively, showed RFLPs. The presence of genetic variati on between strains within these three? divergent morphospecies, which span two orders of cyanobacteria (Chroococcales Wettstein and Nostocal es (Borzi) Geitler), show that the cpcBA-IGS fragment has broad applic ation as a molecular marker for intrageneric studies of cyanobacteria systematics and genetics.