PCR PRIMERS TO AMPLIFY 16S RIBOSOMAL-RNA GENES FROM CYANOBACTERIA

We developed and tested a set of oligonucleotide primers for the speci fic amplification of 16S rRNA gene segments from cyanobacteria and pla stids by PCR. PCR products were recovered from all cultures of cyanoba cteria and diatoms that were checked but not from other bacteria and a rchaea. Gene segments selectively retrieved from cyanobacteria and dia toms in unialgal but nonaxenic cultures and from cyanobionts in lichen s could be directly sequenced. In the context of growing sequence data bases, this procedure allows rapid and phylogenetically meaningful ide ntification without pure cultures or molecular cloning. We demonstrate the use of this specific PCR In combination with denaturing gradient gel electrophoresis to probe the diversity of oxygenic phototrophic mi croorganisms in cultures, lichens, and complex microbial communities.