Thermus diversity and strain loss during enrichment

The diversity of Thermus strains isolated from each of two New Zealand hot pools was examined by isolating partial SSU (16S) rRNA genes and comparing their sequences. Although all of the sequences were similar, several variants were found in each pool. Standard methods for the enrichment of Thermus were then carried out and the gene isolation and sequencing procedure was performed on the enriched isolates. The enrichments resulted in the maintenance of a single dominant strain from each pool and there was a complete loss of heterogeneity in the sequences. These results demonstrate that minor differences in SSU rRNA sequence are indicative of a physiological variance between strains which is of sufficient significance to provide selective advantage or disadvantage during enrichment.