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.     

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.     

The effect of incubation time and temperature on growth of Escherichia coli on gradient plates containing sodium chloride and sodium nitrite

Two-dimensional gradient plates are a convenient way of screening antimicrobial effects of preservative factors acting in combination across a broad range of physical and chemical conditions. We report the effects of sodium chloride, sodium nitrite and incubation temperature on the growth of Escherichia coli by staining, laser densitometry and computer graphics. Staining not only more easily distinguished the growth area but also gave an indication of the viability of cells present. 2-( p -iodophenyl)-3-( p -nitrophenyl)-5-phenyl tetrazolium chloride was the more useful of the two stains used. Inhibitory concentrations of sodium chloride decreased with reduced incubation temperature. The response of E. coli to combinations of salt and nitrite on gradient plates was very similar to its response in liquid medium.     

The effect of incubation time and temperature on growth of Escherichia coli on gradient plates containing sodium chloride and sodium nitrite

Two-dimensional gradient plates are a convenient way of screening antimicrobial effects of preservative factors acting in combination across a broad range of physical and chemical conditions. We report the effects of sodium chloride, sodium nitrite and incubation temperature on the growth of Escherichia coli by staining, laser densitometry and computer graphics. Staining not only more easily distinguished the growth area but also gave an indication of the viability of cells present. 2-(p-iodophenyl)-3(p-nitrophenyl)-5-phenyl tetrazolium chloride was the more useful of the two stains used. Inhibitory concentrations of sodium chloride decreased with reduced incubation temperature. The response of E. coli to combinations of salt and nitrite on gradient plates was very similar to its response in liquid medium.