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  • 1
    Electronic Resource
    Electronic Resource
    Growth yields and the efficiency of oxidative phosphorylation of Paracoccus denitrificans during two- (carbon) substrate-limited growth (1979)
    Springer
    Archives of microbiology 121 (1979), S. 213-223 
    Details
    ISSN: 1432-072X
    Keywords: Oxidative phosphorylation ; Chemostat culture ; Growth yield ; Mixed substrates ; Ribulose-bisphosphate cycle ; Cytochrome c ; Single cell protein ; Methanol ; Paracoccus denitrificans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Paracoccus denitrificans was grown aerobically during two-(carbon)substrate-limitation on mannitol and methanol in chemostat cultures. Theoretical growth parameters were calculated based on the presence of 2 or 3 sites in the electron-transport chain of Paracoccus denitrificans. Experimental growth parameters determined during two-(carbon)substrate growth were conform to the presence of 3 sites of oxidative phosphorylation, while cells grown only on mannitol possessed 2 sites. The maximum growth yield on adenosine triphosphate (ATP), corrected for maintenance requirements, determined in chemostat experiments in which the methanol concentration is less than 2.11 times the mannitol concentration was 8.6 g of biomass. When the methanol concentration was more than 2.11 times the mannitol concentration the maximum growth yield on adenosine triphosphate decreased due to the more energy consuming process of CO2-assimilation. Cells use methanol only as energy source to increase the amount of mannitol used for assimilation purposes. When the methanol concentration in chemostat experiments was more than 2.11 times the mannitol concentration, all mannitol was used for assimilation and excess energy derived from methanol was used for CO2-assimilation via the ribulose-bisphosphate cycle. The synthesis of ribulosebisphosphate carboxylase was repressed when the methanol concentration in chemostat experiments was less than 2.11 times the mannitol concentration or when Paracoccus denitrificans was grown in batch culture on both methanol and mannitol. When in chemostat experiments the methanol concentration was more than 2.11 times the mannitol concentration ribulose-bisphosphate carboxylase activity could be demonstrated and CO2-assimilation will occur. It is proposed that energy produced in excess activates or derepresses the synthesis of the necessary enzymes of the ribulose-bisphosphate cycle in Paracoccus denitrificans. Consequently growth on any substrate will be carbonas well as energy-limited. When methanol is present in the nutrient cells of Paracoccus denitrificans synthesize a CO-binding type of cytochrome c, which is essential for methanol oxidase activity. The reason for the increase in efficiency of oxidative phosphorylation from 2 to 3 sites is most probably the occurrence of this CO-binding type of cytochrome c in which presence electrons preferentially pass through the a-type cytochrome region of the electron-transport chain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425058
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  • 2
    Electronic Resource
    Electronic Resource
    Energy conservation during nitrate respiration in Paracoccus denitrificans (1977)
    Springer
    Archives of microbiology 112 (1977), S. 17-23 
    Details
    ISSN: 1432-072X
    Keywords: Oxidative phosphorylation ; Proton translocation ; Continuous culture ; Maintenance energy ; Growth yield ; Nitrate respiration ; Paracoccus denitrificans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract P/2e ratios were calculated from anaerobic chemostat cultures of Paracoccus denitrificans with nitrogenous oxides as electron acceptor. P/2e ratios were calculated, using the Y ATP max values determined for aerobic cultures. When succinate was the carbon and energy source the average P/2e values of the sulphate-and succinate-limited cultures with nitrate as electron acceptor were 0.5 and 0.7, respectively, and of the nitrite-limited culture 0.9. With gluconate as carbon and energy source the average P/2e values of the gluconate-limited with nitrate as electron acceptor and nitrate limited cultures were 0.9 and 1.1, respectively. →H+/O ratios measured in cells obtained from sulphate-, succinate, nitrite-, gluconate-and nitratelimited cultures yielded respective average values of 3.4, 4.5, 3.5, 4.8 and 6.2 for endogenous substrates. From our data we conclude that sulphate-and nitritelimitation causes the loss of site I phosphorylation. Nitrite has no influence on the maximum growth yield on ATP. We propose that metabolism in heterotrophically grown cells of Paracoccus dentrificans is regulated on the level of phosphorylation in the site I region of the electron transport chain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446649
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  • 3
    Electronic Resource
    Electronic Resource
    Oxidative phosphorylation in Micrococcus denitrificans (1976)
    Springer
    Archives of microbiology 107 (1976), S. 241-247 
    Details
    ISSN: 1432-072X
    Keywords: Oxidative phosphorylation ; Membrane particles ; Continuous culture ; Maintenance energy ; Growth yield ; Micrococcus denitrificans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract P/O ratios were measured in membrane particles obtained from cells of Micrococcus denitrificans, while growing on different carbon sources. The membrane particles obtained from cells growing actively on glucose, succinate, ethanol and propanol as the carbon and energy sources catalyzed oxidative phosphorylation and yielded respective P/O ratios of 1.4, 1.2, 0.8, and 0.5 with NADH, and 0.8, 0.6, 0.6, and 0.5 with succinate as the electron donors. Not such a difference in P/O ratio is observed in intact resting cells grown with different carbon sources. It is concluded that the influence of the carbon source is probably directed towards the efficiency of oxidative phosphorylation in membrane particles and not in the growing cells. For the aerobic carbon source-limited chemostat cultures the following maximum growth yields were determined: 40.2 and 34.2 for succinate and oxgen, 41.7 and 36.5 for malate and oxygen, 81.4 and 39.4 for mannitol and oxygen, and 77.8 and 43.4 for gluconate and oxygen respectively. With a mathematical model (de K waadsteniet et al., in press) the P/O ratio was valued at 1.4–1.7. Y ATP at μ=0.2 was valued at 8.7–10.9; Y ATP max at 9.6–13.2 and m e at 0.6–4.5 for the most precise experiment (gluconate-limited). The calculation of these growth parameters has been discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425334
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  • 4
    Electronic Resource
    Electronic Resource
    Energy conservation during aerobic growth in Paracoccus denitrificans (1977)
    Springer
    Archives of microbiology 112 (1977), S. 25-34 
    Details
    ISSN: 1432-072X
    Keywords: Oxidative phosphorylation ; Proton translocation ; Continuous culture ; Sulphate limitation ; Iron limitation ; Growth yield ; Maintenance energy ; Paracoccus denitrificans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Paracoccus denitrificans was aerobically grown in chemostat culture with succinate or gluconate as carbon source. Due to the presence of two phosphorylation sites in the respiratory chain and the absence of branching, theoretical P/O ratios of 1.71 and 1.82 were calculated for cells growing respectively with succinate and gluconate as carbon source. Using these data, 95% confidence intervals for the P/O ratio were determined, via a mathematical model, at 0.91–1.15 and 1.00–1.37 for sulphate-limited cultures, with respectively succinate and gluconate as carbon source. These results and measurements of P/O ratios in membrane particles and of proton translocation in whole cells have led to the conclusion that site I phosphorylation is affected under sulphate-limited conditions. Under conditions of carbon source-limitation the endogenous →H+/O ratio is about 7–8. Average values of 3.40 and 4.78 were respectively found for sulphate-limited succinate- and gluconate grown cells. For starved cells, oxidizing succinate as exogenous substrate, the →H+/O ratios were determined at about 3–4, independent of the growth limiting factor. It is concluded that the number of protons ejected per pair of electrons per energy-conserving site (→H+/site ratio) is about 3–4, instead of 2 as postulated by the chemiosmotic hypothesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446650
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