Application of temperature-gradient gel electrophoresis in taxonomy of coryneform bacteria

Strains belonging to the Gram-positive coryneform soil bacteria were screen ed genotypically by temperature-gradient gel electrophoresis (TGGE), This m ethod allows the sequence-specific separation of amplified fragments of 16S rRNA genes, A total of 115 reference strains representing the majority of the species of the genera Aeromicrobium, Agromyces, Arthrobacter, Aureobact erium, Cellulomonas, Cortobacterium, Nocardioides and Terrabacter were char acterized. Depending on the genus investigated, the resolution limit of the technique appeared to be at the species or genus level or intermediate bet ween the two. Aberrant TGGE profiles of strains within particular taxa reve aled genomic heterogeneity and generic misclassification of nine strains st udied. Beyond that, indications of 16S rRNA gene heterogeneity were found w ithin the genomes of three Curtobacterium strains. The misclassifications r evealed by TGGE were confirmed using whole-cell fatty acid methyl ester ana lysis and subsequent comparison with a database. TGGE has been demonstrated to be a useful tool in bacterial taxonomy.