| Autor: |
Downs, Andrew J., Jones, Colin W. |
| Zdroj: |
Archives of Microbiology; January 1975, Vol. 105 Issue: 1 p159-167, 9p |
| Abstrakt: |
1.The respiratory chain energy conservation systems of Bacillus megaterium strains D440 and M have been investigated following growth in batch and continuous culture. Respiratory membranes from these strains contained cytochromes b, aa3, o and b, c, a, o, respectively; both readily oxidised NADH but neither showed any pyridine nucleotide transhydrogenase activity.2.Whole cells of both strains exhibited endogenous ?H-/O ratios of approximately 4; when loaded with specific substrates the resultant ?H+/O ratios indicated that proton translocating loops 1 and 2 were present in strain D440 and that loops 2 and 3 were present in strain M.3.In situ respiratory activities were measured as a function of dilution rate during growth in continuous culture. True molar growth yields with respect to oxygen (YO2) of approximately 50 g cells·mole oxygen-1 were obtained for most of the nutrient limitations employed. Average values for YATP of 12.7 and 10.8 g cells·mole ATP equivalents-1 were subsequently calculated for strains D440 and M respectively.4.Energy requirements for maintenance purposes were low in energy-limited cultures but were substantially increased when growth was limited by nitrogen source (NH4+). Under the latter conditions there is probably a partial uncoupling of energy-conserving and energy-utilising processes leading to energy wastage. |
| Databáze: |
Supplemental Index |
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