Identification of ironreducingEmphasis Type="Ita

Authors: D L Balkwill T L Kieft T Tsukuda H M Kostandarithes T C Onstott S Macnaughton J Bownas J K Fredrickson

Publish Date: 2003/10/11

Volume: 8, Issue: 1, Pages: 37-44

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Abstract

Thermus strain SA01 previously isolated from a deep 32 km South African gold mine is closely related to Thermus strains NMX2 A1 and VI7 previously isolated from thermal springs in New Mexico USA and Portugal respectively Thermus strains SA01 and NMX2 A1 have also been shown previously to grow using nitrate FeIII MnIV or SO as terminal electron acceptors and to be capable of reducing CrVI UVI CoIII and the quinonecontaining compound anthraquinone26disulfonate The objectives of this study were to determine the phylogenetic positions of the three known metalreducing Thermus strains and to determine the phylogenetic significance of metal reduction within the genus Thermus Phylogenetic analyses of 16S rDNA sequences BOX PCR genomic fingerprinting and DNA–DNA reassociation analyses indicated that these strains belong to the previously described genospecies T scotoductus The morphologies and lipid fatty acid profiles of these metalreducing strains are consistent with their identification as T scotoductus however the T scotoductus strains tested in this study evinced a wide intraspecies variability in some other phenotypic traits eg carbon substrate utilization and pigmentation Iron reduction occurred in all strains of T scotoductus tested except the mixotrophic sulfuroxidizing strain IT7254 Thermus strains belonging to other species did not reduce FeIII to FeII or reduced it only poorlyWe thank Mary McHale and Gwendolyn R Drake for technical assistance This research was supported by grant no EAR9978267 from the National Science Foundation Life in Extreme Environments LExEn Program and by grants from the National Aeronautics and Space Administration’s Astrobiology Institute

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