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 varian
ts were found in each pool. Standard methods for the enrichment of Thermus
were then carried out and the gene isolation and sequencing procedure was p
erformed on the enriched isolates. The enrichments resulted in the maintena
nce of a single dominant strain from each pool and there was a complete los
s of heterogeneity in the sequences. These results demonstrate that minor d
ifferences in SSU rRNA sequence are indicative of a physiological variance
between strains which is of sufficient significance to provide selective ad
vantage or disadvantage during enrichment. (C) 1999 Federation of European
Microbiological Societies, Published by Elsevier Science B.V. All rights re
served.