Evaluation of 16S rDNA & gyrB sequences for taxonomic analyses of heavy metal resistant actinomycetes

ALBARRACÍN V.H.; POLTI M. A.; AMOROSO M. J.; ABATE C.M.

Rosario, Mendoza, Argentina

Simposio; XLII REUNION ANUAL SAIB; 2006

SAIB

Actinomycetes are high G+C, Gram-positive bacteria particularly abundant in soil that produce bioactive compounds of biotechnological importance. Analysis of 16S rRNA sequences is a simple, commonly used method for the identification of microorganisms but it was demonstrated that gyrB gene sequences may also be applied to perform phylogenetic analyses of Streptomyces and other actinobacteria. In this work, the convenience of using 16S rDNA and gyrB sequences for taxonomic analyses of heavy metal resistant actinomycetes is evaluated. Total genomic DNA of heavy metal resistant actinomycetes strains was amplified with 16S universal and gyrB specific primers. The obtained DNA sequences and closely related species sequences from public databases were aligned and compared while phylogenetic trees were constructed by the neighboring-joining method. According to 16s rDNA sequence analysis, the isolated strains belonged to the genus Streptomyces(10) and Amycolatopsis (2). gyrB gene sequence characterize the same ten strains as Streptomyces but failure to identify the rest as Amycolatopsis strains. In addition, trees constructed with the related species from public databases were different depending on the taxonomic marker used. We conclude that the gyrB public database is still incomplete for Streptomyces and has not been developed yet to Amycolatopsis. Nevertheless, as it was considered before as an useful target for the phylogenetic analyses of members of actinobacteria with this work we are currently contributing to construct a database of gyrB sequences for further re-classification of Streptomyces and Amycolatopsis species.