Oxidative phosphorylation in Micrococcus denitrificans

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 =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.     

Zur Rolle des Hefeextraktes während des chemolithotrophen Wachstums von Micrococcus denitrificans

Ohne Zusammenfassung     

Phospholipid Composition and Metabolism of Micrococcus denitrificans

The phospholipid composition of Micrococcus denitrificans was unusual in that phosphatidyl choline (PC) was a major phospholipid (30.9%). Other phospholipids were phosphatidyl glycerol (PG, 52.4%), phosphatidyl ethanolamine (PE, 5.8%), an unknown phospholipid (5.3%), cardiolipin (CL, 3.2%), phosphatidyl dimethylethanolamine (PDME, 0.9%), phosphatidyl monomethylethanolamine (PMME, 0.6%), phosphatidyl serine (PS, 0.5%), and phosphatidic acid (0.4%). Kinetics of ³²P incorporation suggested that PC was formed by the successive methylations of PE. Pulse-chase experiments with pulses of ³²P or acetate-1-¹⁴C to exponentially growing cells showed loss of isotopes from PMME, PDME, PS, and CL with biphasic kinetics suggesting the same type of multiple pools of these lipids as proposed in other bacteria. The major phospholipids, PC, PG, and PE, were metabolically stable under these conditions. The fatty acids isolated from the complex lipids were also unusual in being a simple mixture of seven fatty acids with oleic acid representing 86% of the total. Few free fatty acids and no non-extractable fatty acids associated with the cell wall or membrane were found.     

Wachstumsphysiologische Untersuchungen an Micrococcus denitrificans Beij.

Ohne ZusammenfassungGekürzte gleichlautende Dissertation der mathematisch-naturwissenschaftlichen Fakultät der Universität Göttingen 1964.     

Specific thiamine monophosphate phosphohydrolase in Micrococcus denitrificans.

A phosphohydrolase specific for thiamine monophosphate was isolated from Micrococcus denitrificans, partially purified approximately 100-fold, and separated from acid phosphatase.     

Vorkommen von Azotobacter agilis Beijerinck in Deutschland

Zusammenfassung Das Vorkommen von Azotobacter agilis wurde in der Umgebung von Göttingen in 2 größeren wenig verschmutzten Gewässern (Seeburger See, Kiesgrube) nachgewiesen, nicht dagegen in reinen Quellteichen und in stark verschmutzten Gewässern. Die selten gelungene Isolierung dieses Organismus ist wohl auf eine Überwucherung durch Az. chroococcum zurückzuführen.     

The autotrophic growth of Micrococcus denitrificans on Methanol.

Ribulose bisphosphate carboxylase is present at a high specific activity in extracts of methanol-grown Microccus denitrificans. Enzymic and physiological evidence indicates that, during growth on methanol, the ribulose bisphosphate cycle is the route of carbon assimilation.     

Oxidative phosphorylation in Micrococcus denitrificans under autotrophic growth conditions

Summary Cell-free preparations from autotrophically grown M. denitrificans yielded P/O ratios of 0.6–1.6 with H₂, 0.4–1.2 with NADH, 0.7–1.0 with succinate, and 0.3–0.5 with ascorbate as the oxidizable substrates.The phosphorylation in all cases was inhibited effectively by DNP, DBP, PCP, CCCP, and dicumarol at concentrations which did not cause any significant inhibition of oxygen uptake.The respiratory chain inhibitors such as antimycin A, HOQNO, cyanide, and azide were the potent inhibitors of the phosphate esterification coupled to the oxidation of H₂, NADH, and succinate; the ascorbate-linked phosphorylation was inhibited by cyanide or azide only.While the NADH oxidation and associated phosphorylation was markedly sensitive to rotenone and other flavoprotein inhibitors, the oxidation of H₂ was relatively insensitive although there was a partial inhibition of the coupled phosphorylation. The experimental results indicated that bulk of the electron transfer from H₂ bypassed the NADH-dehydrogenase or the rotenone sensitive site.Non-standard Abbreviations BAL British Anti-Lewisite (2,3-Dimercaptopropanol) - CCCP Carbonyl-cyanide-m-chlorophenylhydrazone - DBP 2,6-Dibromophenol - DNP 2,4-Dinitrophenol - GSH reduced glutathione - HOQNO 2-n-Heptyl-4-hydroxyquinoline-N-oxide - PCMB p-hydroxymercuribenzoate - PCP Pentachlorphenol - TTFA Thenoyltrifluoracetone - TMPD N,N,N,N-tetramethyl-p-phenylenediamine - BSA Bovine serum albumin - EDTA Ethylenediamine tetraacetic acid Post doctorate fellow of the Deutsche ForschungsgemeinschaftNational Science Foundation Research Associate.