ISSN:
1432-072X
Keywords:
Electrochemical proton gradient
;
ΔΨ
;
Electron transfer
;
CO2 uptake
;
thiobacillus neapolitanus
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Uptake of inorganic carbon (Ci) in the form of CO2 and/or HCO 3 - was studied in the chemolithoautotroph Thiobacillus neapolitanus under energy (thiosulphate) or carbon (CO2) limitation. Uptake of C1 was found to be a metabolic energy dependent process since in the presence of uncouplers no uptake was observed. The accumulation level of Ci was higher in the CO2-limited cells (1000-to 1500-fold) in comparison to the thiosulphate-limited cells (500-to 800-fold). The process of uptake could be influenced by addition of ionophores. Inhibition of uptake and accumulation of Ci was found after addition of valinomycin which completely dissipated the electrical potential (ΔΨ). After addition of nigericin an increase in the uptake and accumulation of Ci was observed with a concomitant increase of the ΔΨ. These results suggest that the ΔΨ is the main driving force for uptake of Ci. However, uptake of Ci could never be found in the absence of electron transfer, or in cells in which the electron transfer chain was blocked by potassium cyanide. Electron transfer therefore appears to be an additional requirement for Ci uptake. Kinetic experiment on the uptake of inorganic carbon at different pH values suggest that CO2 is the carbon species taken up by T. neapolitanus.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00463489
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