ISSN:
1432-072X
Keywords:
Key words Thermoproteus tenax
;
Pyrobaculum
;
islandicum
;
Hyperthermophiles
;
Archaea
;
Acetyl-CoA oxidation
;
Citric acid cycle
;
Sulfur respiration
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The oxidation of organic compounds with elemental sulfur or thiosulfate as electron acceptor was studied in the anaerobic hyperthermophilic archaea Thermoproteus tenax and Pyrobaculum islandicum. T. tenax was grown on either glucose or casamino acids and sulfur; P. islandicum on peptone and either elemental sulfur or thiosulfate as electron acceptor. During exponential growth only CO 2 and H2S rather than acetate, alanine, lactate, and succinate were detected as fermentation products of both organisms; the ratio of CO2/H2S formed was 1 : 2 with elemental sulfur and 1 : 1 with thiosulfate as electron acceptor. Cell extracts of T. tenax and P. islandicum contained all enzymes of the citric acid cycle in catabolic activities: citrate synthase, aconitase, isocitrate dehydrogenase (NADP+ -reducing), oxoglutarate : benzylviologen oxidoreductase, succinyl-CoA synthetase, succinate dehydrogenase, fumarase and malate dehydrogenase (NAD+-reducing). Carbon monoxide dehydrogenase activity was not detected. We conclude that in T. tenax and P. islandicum organic compounds are completely oxidized to CO2 with sulfur or thiosulfate as electron acceptor and that acetyl-CoA oxidation to CO2 proceeds via the citric acid cycle.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00301853
Permalink
