The Occurrence of Polythionates as Intermediates in the Metabolism of Thiosulphate by the Thiobacilli

Self Cite

Section: Introductionsupporting

confidence: 85%

Some Metabolic Differences Between Thiobacillus thioparus, T. denitrificans and T. thiocyanoxidans

Woolley

Jones

Happold

1962

Self Cite

“…Several workers have reported the accumulation of tetrathionate during the oxidation of sulphur compounds by suspensions of thiobacilli (Vishniac, 1952 ;Baalsrud & Baalsrud, 1954; Vishniac & Santer, 1957; Trudinger, 1959; Jones & Happold, 1961).…”

Section: Introductionmentioning

confidence: 99%

The Role of Tetrathionate in the Oxidation of Thiosulphate by Chromatium sp. strain D

Smith¹

1966

SUMMARYSulphate was progressively replaced by tetrathionate as the end product of thiosulphate oxidation by suspensions of Chromatium D when the pH value was decreased from 7-3 to 6-25; tetrathionate was not itself oxidized to sulphate within this range. The effect of pH value on the oxidation of endogenous sulphur was less marked than on the production of sulphate from thiosulphate. Extracts of Chromatium D catalysed the oxidation of thiosulphate to tetrathionate in the presence of ferricyanide; pH 5.0 was the optimum of the purified enzyme. Tetrathionate inhibited growth and the complete oxidation of thiosulphate by suspensions. At pH 6-75 where sulphur accumulated during thiosulphate utilization and sulphate and tetrathionate were formed, added tetrathionate inhibited the accumulation of endogenous sulphur but not the production of tetrathionate from thiosulphate. Tetrathionate had no effect on the oxidation of endogenous sulphur by suspensions. It is concluded that in Chromatium D thiosulphate is metabolized by two alternative pathways depending on the conditions : (1) the cleavage of one molecule of thiosulphate in a reaction similar to that catalysed by thiosulphate sulphur-transferase E. (2.2.8 .I. 1. (rhodanese); (2) the oxidative coupling of two molecules of thiosulphate to give tetrathionate, catalysed by the thiosulphate-oxidizing enzyme which only operates at low pH values.

“…One possible explanation is that, though the same pathway may be followed, the rates of reaction differ because of inherent differences between the strains in, for example, cell-wall composition and permeability. Pratt (1958) and Jones & Happold (1961) also found that cultures of T . thiocyanoxidans produced less polythionate than cultures of T .…”

Section: Discussionmentioning

confidence: 90%

Polarographic Evidence of the Production of Polythionates During the Bacterial Oxidation of Thiosulphate

Pankhurst¹

1964

SUMMARYA polarographic technique and Starkey's alkali method have been applied to the qualitative analysis of thiosulphate, trithionate and pentatliionate and to the quantitative analysis of tetrathionate in filtrates of bacterial cultures grown in an inorganic medium containing sodium thiosulphate. Five strains of autotrophic thiobacilli and one strain of a heterotrophic bacterium produced polythionates. During thiosulphate oxidation by two autotrophic strains which resembled Thiobacillus thiopaws, tetrathionate, small amounts of trithionate, pentathionate and abundant elemental sulphur were produced and the pH fell from c. 7.0 to c. 3-0. I n cultures of one of the three autotrophic strains which resembled T. thiocyanoxidans, about half as much tetrathionate, with even smaller amounts of trithionate and pentathionate, was found; abundant sulphur was precipitated and the pH fell to c. 4.0. I n cultures of the two other strains iesembling T. thiocyanozidans, small amounts of tetrathionate were detected only occasionally ; trithionate and pentathionate were not found, sulphur was deposited and the pH fell to c. 4.5. Much tetrathionate, as well as trithionate and pentathionate, were all readily identified in cultures of the heterotrophic organism; the pH rose to c. 8.7 and no sulphur was formed.