Carbon catabolism in continuous cultures and bacteroids of Rhizobium leguminosarum MNF 3841 |
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Authors: | I A McKay M J Dilworth A R Glenn |
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Institution: | (1) School of Biological and Environmental Sciences, Murdoch University, 6150 Murdoch, Western Australia;(2) Present address: Department of Food Technology, Massey University, Palmerston North, New Zealand |
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Abstract: | Bacteroids of R. leguminosarum MNF3841 isolated from pea nodules using Percoll gradients had activities of TCA cycle enzymes up to 6-fold higher than those measured in free-living cells grown on fumarate or sucrose. Activities of sugar catabolic enzymes on the other hand were 2–14-fold lower in isolated bacteroids than in sucrose-grown free-living cells. In continuous culture, cells of strain MNF3841 grown on sucrose under P
i limitation had 2–3-fold higher activities of invertase, glucose-6-phosphate dehydrogenase, the Entner-Doudoroff enzymes and 6-phosphogluconate dehydrogenase, than cells grown on fumarate. With one exception O2 limited cultures had similar activities of the carbon catabolic enzymes to P
i-limited cultures grown in the same substrate. Glucose-6-phosphate dehydrogenase in O2-limited cells grown of fumarate was 50% lower than in P
i-limited cells. Co-utilization of fumarate and sucrose occurred with chemostat cultures supplied with both under a variety of conditions.Abbreviations E-D
Entner-Doudoroff
- EMP
Embden-Meyerhof-Parnas
- PEPCK
phosphoenolpyruvate carboxy kinase
- HEPES
N-2-hydroxyethyl]piperazine-N-2-ethanesulphonic acid] |
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Keywords: | Rhizobium leguminosarum Catabolic enzymes Bacteroids Percoll gradients Chemostats Substrate consumption |
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