Occurrence,structure and function of intracellular polyglucose in the obligate chemolithotroph Thiobacillus neapolitanus |
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Authors: | R F Beudeker J W M Kerver J G Kuenen |
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Institution: | (1) Department of Microbiology, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands;(2) Present address: Department of Microbiology, Delft University of Technology, Julianalaan 67A, 2628 BC Delft, The Netherlands |
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Abstract: | Nitrogen-limited cells of the obligate chemolithotroph Thiobacillus neapolitanus formed an intracellular polymer during growth in the chemostat. This polymer was isolated and characterized as a branched polyglucose composed of units joined by -14 and -16 linkages. Polyglucose in T. neapolitanus can be considered a storage compound since formation of this compound took place during excess of energy and CO2 whilst shortage of CO2 resulted in rapid breakdown of polyglucose. Moreover the breakdown of polyglucose generated metabolically useful energy as could be demonstrated by polyglucose-dependent protein synthesis. Possession of polyglucose did not influence the viability of T. neapolitanus during prolonged periods of energy starvation. Activities of key enzymes of the oxidative pentose phosphate cycle, glucose-6-phosphatedehydrogenase and 6-phospho-gluconate-dehydrogenase, were demonstrated in cell free extracts of T. neapolitanus and appeared to increase 5- and 3-fold, respectively, during growth on NO
3
-
instead of NH
4
+
as a nitrogen source. |
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Keywords: | Polyglucose Chemolithotroph Thiobacillus neapolitanus |
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