New PCR primers for the selective amplification of 16S rDNA from different groups of actinomycetes1

Actinomycetes play a relevant role in soil ecology and are also of important biotechnological interest as they produce several bioactive metabolites. Within the filamentous actinomycetes, it would be desirable to recognize and characterize environmental samples containing unusual genera. To this end, we have developed selective primer sets for polymerase chain reaction (PCR) amplification of 16S rDNA from the Actinomycetales families Micromonosporaceae, Streptomycetaceae, Streptosporangiaceae and Thermomonosporaceae, and from the genus Dactylosporangium. Each primer set, evaluated on genomic DNA from reference strains, showed high specificity and good sensitivity. After amplification of DNA extracted from soil samples, the sequence of the cloned PCR products confirmed the specific amplification of the desired group of sequences in at least 95% of the clones for each primer set. The application of these primers to environmental samples showed the frequent occurrence of these groups in soil samples and also revealed sequences that can be attributed to new groups of actinomycetes.