Ein ungewöhnlicher Stärkeabbauweg im hyperthermophilen archaeellen Sulfatreduzierer Archaeoglobus fulgidus Stamm 7324 und Charakterisierung Stärke-abbauender Enzyme aus geothermalen Habitaten
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Elektronische Hochschulschrift;
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Titel:
Ein ungewöhnlicher Stärkeabbauweg im hyperthermophilen archaeellen Sulfatreduzierer Archaeoglobus fulgidus Stamm 7324 und Charakterisierung Stärke-abbauender Enzyme aus geothermalen Habitaten
Beteiligte:
Labes, Antje
[VerfasserIn]
Erschienen:
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel), 2005
Umfang:
text
Sprache:
Deutsch
Entstehung:
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Beschreibung:
Comparative analyses of sugar catabolism in archaea revealed that degradation of glucose and hexose polymers proceeds via modified glycolytic pathways, mainly via modified Embden-Meyerhof pathways. The utilization of sugars by Archaeoglobus fulgidus species, which represent the first isolated archaeal sulfat reducer, has not unequivocally been demonstrated so far. Thus, in this thesis it was found that Archaeoglobus fulgidus strain 7324, rather than the type strain VC16, was able to grow on starch and sulfate as energy and carbon source. Starch was degraded to acetate via an unusual starch degradation pathway. Some key enzymes were purified and characterized. Furthermore, starch degrading and modifying enzymes from geothermal habitats were characterized to find properties useful for biotechnological applications. 2.1 Starch degradation in A. fulgidus strain 7324 A. fulgidus strain 7324 was found to grow on starch (1 g/l) and sulfate (30 mM) in presence of yeast extract (0.5 g/l) as energy and carbon source. During exponential growth on starch, 1 mol of glucose-equivalent was incompletely oxidized with sulfate to approximately 2 mol acetate, 2 mol CO2 and 1 mol H2S. Beside starch, amylose and β-cyclodextrin were used as substrates. Other sugars, e.g. glucose, fructose and maltose were not utilized. This is the first report of growth of a sulfate reducer on starch, i.e. on a polymeric sugar. Extracts of starch-grown cells of A. fulgidus Stamm 7324 contained all activites of an unusual starch degradation pathway to acetate, which includes the conversion of starch to glucose 6-phosphate as well as the conversion of glucose to pyruvate via a modified Embden-Meyerhof pathway. Specific activities of the key enzymes of the starch conversion to acetate were significantly higher in starch-grown cells than in lactate-grown cells, indicating induction of these enzymes during starch catabolism. In A. fulgidus strain VC16 neither enzyme activities of starch degradation nor the corresponding homologous genes were detected. ...