Original Papers

Archives of Microbiology

, Volume 160, Issue 2, pp 152-157

First online:

Chemolithoutotrophic growth of Thiothrix ramosa

  • Elena V. OdintsovaAffiliated withDivision of Life Sciences, King's College London
  • , Ann P. WoodAffiliated withDivision of Life Sciences, King's College London
  • , Don P. KellyAffiliated withNatural Environment Research Council

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Abstract

Thiothrix has been shown for the first time to be able to grow chemolithoautotrophically with thiosulphate or carbon disulphide as sole energy substrate. Thiosulphate served as the growth-limiting substrate for Thiothrix ramosa in chemostat culture. Maximum growth yield (Ymax) from yields at growth rates between 0.029–0.075 h-1 was 4.0 g protein/mol thiosulphate oxidized. The key enzyme of the Calvin cycle, ribulose 1,5-bisphosphate carboxylase, was present in these cells, as were rhodanese, adenylyl sulphate (APS) reductase and ‘sulphur-oxidizing enzyme’. Thiosulphate-grown cells oxidized thiosulphate, sulphide, tetrathionate and carbon disulphide. Oxidation kinetics for sulphide, thiosulphate and tetrathionate were biphasic: oxygen consumption during the fast first phase of oxidation indicated oxidation of sulphide, and the sulphane moieties of thiosulphate and tetrathionate, to elemental sulphur, before further oxidation to sulphate. Kinetic constants for these four substrates were determined. T. ramosa also grew mixotrophically in batch culture on lactate with a number of organic sulphur compounds: carbon disulphide, methanethiol and diethyl sulphide. Substituted thiophenes were also used as sole substrates. The metabolic versatility of T. ramosa is thus much greater than previously realised.

Key words

Thiothrix ramosa Chemolithoautotrophy Chemostat Ribulose bisphosphate carboxylase