Phylogenetic characterization of two thermophilic bacteria isolated from thermal springs in Argentina

AMADIO A; TORRES R; ZANDOMENI RO

Villa Carlos Paz

Congreso; XXXVIII Reunión Anual SAIB; 2002

SAIB

Two thermophilic bacteria were isolated from thermal springs in Argentina. One of them, called 2.9, is a thermophilic aerobic rod-shaped bacteria, which grows at 60ºC. The other one, called T6, is a thermophilic neutrophilic aerobic or facultatively anaerobic rod that also grows at 60ºC. Both them grow on different basal media. The gene encoding for the 16S rRNA (16S rDNA) was amplified by PCR with universal primers for bacterial 16S rDNA. The products were cloned in pGEM-T-Easy vector. The nucleotide sequence of 16S rDNA was determined by using plasmid DNA as template and 16S rDNA specific primers. The sequence of 2.9 showed phylogenetic relationships to the genus Thermus (~95-98%), and the highest homology was found with T. brockianus 16S rDNA sequence (98%). The sequence of 16S rDNA of T6 showed a phylogenetic relationship (homology of ~99) to the genetic group 5 of thermophilic bacilli, the Geobacillus genus. This high homology is characteristic of this genus. The highest homology was seen with G. thermocatenulatus. A genomic library was constructed for both isolates by digesting genomic DNA with the restriction endonuclease Sau3AI and cloning the fragments in the BamHI site of a plasmid vector. A gene discovery strategy was started by random sequencing of clones.