Phosphate-limited growth of Chromatium vinosum in continuous culture |
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Authors: | Jordi Mas Hans van Gemerden |
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Institution: | (1) Department of Microbiology, University of Groningen, Kerklaan 30, NL-9751 NN Haren, The Netherlands;(2) Present address: Department of Genetics and Microbiology, Autonomous University of Barcelona, E-08193 Bellaterra, Spain |
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Abstract: | Chromatium vinosum DSM 185 was grown in continuous culture at a constant dilution rate of 0.071 h-1 with sulfide as the only electron donor. The organism was subjected to conditions ranging from phosphate limitation (S
R-phosphate=2.7 M and S
R-sulfide=1.8 mM) to sulfide limitation (S
R-phosphate=86 M and S
R-sulfide=1.8 mM). At values of S
R-phosphate below 7.5 M the culture was washed out, whereas S
R-phosphate above this value resulted in steady states. The saturation constant (K
) for growth on phosphate was estimated to be between 2.6 and 4.1 M. The specific phosphorus content of the cells increased from 0.30 to 0.85 mol P mg-1 protein with increasing S
R-phosphate. The specific rate of phosphate uptake increased with increasing S
R-phosphate, and displayed a non-hyperbolic saturation relationship with respect to the concentration of phosphate in the inflowing medium. Approximation of a hyperbolic saturation function yielded a maximum uptake rate (V
max) of 85 nmol P mg-1 protein h-1, and a saturation constant for uptake (K
t) of 0.7 M. When phosphate was supplied in excess 8.5% of the phosphate taken up by the cells was excreted as organic phosphorus at a specific rate of 8 nmol P mg-1 protein h-1.Non-standard abbreviations BChla
bacteriochlorophyll a
- D
dilution rate; max, maximum specific growth rate
-
maximum specific growth rate if the substrate were not inhibitory
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K
saturation constant for growth on phosphate
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V
max
maximum rate of phosphate uptake
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K
i
saturation constant for phosphate uptake
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K
i
inhibition constant for growth in the presence of sulfide
-
S
R
concentration of substrate in the inflowing medium |
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Keywords: | Chromatium vinosum Phosphate Nutrient limitation Continuous culture Phototrophic bacteria |
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