The temperature profile was the one previously described by Vinuesa et al. [18], except for the extensionof the initial denaturation step to 7 min, as required by Ampli-Taq Gold polymerase. Amplification products were run on 1% agarosegels and the bands were purified using the Quiaex II kit (Quia-gen, Germany).
The nucleotide sequence of the purified bands was determined by the dideoxy chain-termination method, using the ABI-PRISM Big Dye Terminator Cycle Sequencing Ready Reaction kit (Perkin Elmer, USA) and automated sequencer ABI PRISM 3100 Avant Genetic Analyzer (Applied Biosystems, Germany). The sequenced fragment analyzed corresponded to the first 650 bp ofthe 16S rRNA gene, comprising hypervariable regions V1, V2 andV3 [19].