Isolation and characterization of a mixotrophic sulfur-oxidizing Thermus scotoductus

Sigurlaug Skirnisdottir, Gudmundur O. Hreggvidsson, Olle Holst, Jakob K. Kristiansson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)


Thermophilic, faculatatively mixotrophic sulfur-oxidizing bacteria were isolated from a sulfide-rich, neutral hot spring in Iceland. The strain, IT-7254, used thiosulfate and elemental sulfur as electron donors, oxygen and nitrate as electron acceptors, and acetate and other organic compounds as carbon sources. After a few days of growth in the presence of thiosulfate, this strain formed sulfur globules. Comparison of intracellular enzymes and heme proteins of heterotrophically and mixotrophically grown cells showed some differences. The new isolate belonged to Thermus scotoductus because the small subunit (SSU) rRNA gene sequence analysis showed 98.6% sequence similarity and 84% DNA:DNA reassociation to Thermus scotoductus NMX2 A.1. It is also close to Thermus antranikianii HN3-7, with 98.3% and 79% SSU rRNA sequence similarity and DNA:DNA reassociation, respectively. It was also found that both Thermus NMX2 A.1 and T. antranikianii HN3-7 were able to oxidize thiosulfate but that the T. scotoductus type strain SE-1 was not. This is the first report of Thermus strains that are capable of mixotrophic growth with sulfur oxidation.

Original languageEnglish
Pages (from-to)45-51
Number of pages7
Issue number1
Publication statusPublished - 2001

Bibliographical note

Funding Information:
Iceland for the electron microscopy and Hugh Morgan, University of Waikato, Hamilton, New Zealand, for providing Thermus strain NMX2 A.1. This work was supported by The European Union, grant no. Bio4-CT96–0488.

Other keywords

  • Hot spring
  • Mixotrophic
  • Sulfur-oxidizing bacteria Thermus


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