A preliminary grouping of new zealand Thermus strains by pyrolysis-mass spectrometry

Abstract

Isolates belonging to the genus Thermus are readily obtained from many thermal environments but their exact identification is difficult because there is no general agreement on criteria which determine individual species. We present an attempt to determine natural groupings among Thermus strains using the technique of pyrolysis-mass spectrometry. A total of forty-four strains comprising forty isolates from New Zealand hot springs, one from a Fijian hot spring and three reference strains were pyrolysed in a Pyromass 8–80 and the resulting data analysed using multivariate statistical techniques. A dendrogram obtained by average linkage cluster analysis of discriminant distances showed clear discrimination of the three reference strains from each other and from the majority of the New Zealand strains. Thirty New Zealand isolates clustered within a single group, probably at a species level. At a higher level of similarity six sub-groups could be identified within this cluster which presumably represent grouping at a variety level. The non-pigmented reference strain “Ramaley's XI” occupied a rather isolated position in the dendrogram. It appears that pyrolysis-mass spectrometry is useful for rapid characterisation of isolates obtained from ecological studies and offers the possibility of detecting groupings at both species and sub-species levels.