Oxidative metabolism of lactate and acetate by Micrococcus sodonensis

OXIDATIVE ASSIMILATION OF GLUCOSE BY PSEUDOMONAS AERUGINOSA

Duncan, Margaret G. (The University of British Columbia, Vancouver, British Columbia, Canada) and J. J. R. Campbell. Oxidative assimilation of glucose by Pseudomonas aeruginosa. J. Bacteriol. 84:784-792. 1962-Oxidative assimilation of glucose by washed-cell suspensions of Pseudomonas aeruginosa was studied using C(14)-labeled substrate. At the time of glucose disappearance, only small amounts of radioactivity were present in the cells, and alpha-ketoglutaric acid accumulated in the supernatant fluid. Most of the material synthesized by the cells during oxidative assimilation was nitrogenous, the ammonia being supplied by the endogenous respiration. The cold trichloroacetic acid-soluble fraction and the lipid fraction appeared to be important during the early stages of oxidative assimilation, and the largest percentage of the incorporated radioactivity was found in the protein fraction. In the presence of added ammonia, assimilation was greatly increased and no alpha-ketoglutaric acid was found in the supernatant fluid. Sodium azide partially inhibited incorporation into all major cell fractions, and at higher concentrations depressed the rate of glucose oxidation. During oxidative assimilation, chloramphenicol specifically inhibited the synthesis of protein. Oxidative assimilation of glucose by this organism did not appear to involve the synthesis of a primary product such as is found in the majority of bacteria.

Role of potassium in the oxidative metabolism of Micrococcus sodonensis

Perry, Jerome J. (The University of Chicago, Chicago, Ill.), and James B. Evans. Role of potassium in the oxidative metabolism of Micrococcus sodonensis. J. Bacteriol. 82:551-555. 1961.-An absolute potassium requirement has been established for the growth of Micrococcus sodonensis with lactate or pyruvate as substrate. Potassium at 0.67 x 10(-2)m concentration was necessary for maximal growth. Resting cell and cell-free preparations from cells grown on minimal levels of potassium were stimulated by potassium but, due to residual or bound cation, did not show an absolute requirement. Rubidium and cesium replaced potassium in these cells although cesium is much less effective.

An extracellular material elaborated by Micrococcus sodonensis

Campbell, J. N. (American Meat Institute Foundation, Chicago, Ill.), James B. Evans Jerome J. Perry, and C. F. Niven, Jr. An extracellular material elaborated by Micrococcus sodonensis. J. Bacteriol. 82:828-837. 1961.-When actively growing in a yeast extract-tryptone broth, Micrococcus sodonensis produced rather large quantities of an extracellular material. On a dry weight basis, this material consisted of approximately 80% deoxyribonucleic acid (DNA), 6% ribonucleic acid, 13% protein, and a small quantity of a cell pigment which contained an associated iron porphyrinlike compound. The extracellular material was not produced in other complex or synthetic media. Removal of cells from the appropriate growth medium and suspension in distilled water resulted in the prevention of formation of the material if it had not already begun, or its immediate cessation in those cells which had been actively producing the material. Cells producing the extracellular material exhibited an increasingly higher concentration of intracellular DNA as incubation proceeded, whereas cells growing under conditions not supporting such production showed a decline in intracellular DNA as the culture aged. A similar increase of intracellular DNA, but not release of extracellular material, could be effected by addition of yeast extract or high levels of purine compounds to a medium which did not support the production of extracellular material. The base composition and ratios of both extracellular and intracellular DNA produced under all conditions tested were compared and found to be similar or identical, and to correspond to the classical Watson-Crick structure for DNA.

Glucose catabolism in Micrococcus sodonensis

The inability of Micrococcus sodonensis to grow on glucose as the sole source of carbon and energy was investigated. Estimation of pathways of glucose catabolism indicated that both the glycolytic and hexose monophosphate pathways are present in this organism. Comparative studies with Escherichia coli demonstrated that key enzymes for glucose catabolism were present in M. sodonensis in quantities equivalent to those of E. coli. The glucose-6-phosphate and 6-phosphogluconate dehydrogenases of M. sodonensis were nicotinamide adenine dinucleotide phosphate (NADP) specific, and glyceraldehyde-3-phosphate dehydrogenase was nicotinamide adenine dinucleotide specific. Transhydrogenase and reduced NADP oxidase were absent. Growth of the organism in the presence of glucose did not result in a repressed ability to oxidize tricarboxylic acid cycle intermediates, but these cells did have a decreased capacity for glucose degradation. The addition of substrates rich in growth-promoting substances, e.g., yeast extract, did not provide requisite nutrients for growth on glucose. Studies with (32)P suggest that M. sodonensis is incapable of synthesizing energy-rich phosphate compounds during the catabolism of glucose.

Oxidation and assimilation of carbohydrates by Micrococcus sodonensis

Perry, Jerome J. (North Carolina State University, Raleigh), and James B. Evans. Oxidation and assimilation of carbohydrates by Micrococcus sodonensis. J. Bacteriol. 91:33-38. 1966.-Micrococcus sodonensis is a biotin-requiring strict aerobe that cannot utilize carbohydrates as sole sources of carbon and energy. However, addition of mannose, glucose, sucrose, or maltose to a medium on which the organism can grow resulted in an increase in total growth. M. sodonensis oxidized these sugars without induction, thus indicating the presence of constitutive enzymes for their transport, activation, and metabolism. Under appropriate nonproliferating cell conditions, glucose was readily incorporated into essential constituents of the cell. When glucose-1-C(14) and glucose-6-C(14) were oxidized by nonproliferating cells, the label was found in both the protein and nucleic acid fractions of the cell. The respiratory quotients of cells oxidizing glucose in saline and in phosphate buffer indicated assimilation of sugar carbon in buffer and virtually no assimilation in saline. The ability of M. sodonensis to completely oxidize glucose and to grow on intermediates of glucose oxidation but not on glucose suggests that glucose may suppress or repress some reaction(s) necessary for growth, and that growth substrates either derepress or circumvent this block.

EFFECT OF AMMONIUM ION ON GROWTH AND METABOLISM OF MICROCOCCUS SODONENSIS

Campbell , J. N. (American Meat Institute Foundation, Chicago, Ill.), James B. Evans, Jerome J. Perry, and C. F. Niven, Jr. Effect of ammonium ion on growth and metabolism of Micrococcus sodonensis . J. Bacteriol. 82: 823–827. 1961.—When Micrococcus sodonensis was grown in a synthetic medium deficient in ammonia, large quantities of α-keto acids, chiefly α-ketoglutaric, accumulated in the medium. The addition of ammonium chloride to this medium prevented such accumulation and also supported increased growth, even in the presence of excess glutamate. Neither potassium nor sodium would substitute for ammonia in producing this effect.

The results indicate that this microorganism has a specific requirement for the ammonium ion in its growth and metabolism. If not supplied exogenously, ammonia is made available by deamination of glutamic acid. The exact route of incorporation of ammonia is unknown.

A MINIMAL SYNTHETIC MEDIUM SUPPORTING GROWTH OF A MICROCOCCUS SPECIES

Nutritional requirements of a Micrococcus species (M. freudenreichii, A.T.C.C. No. 407) were studied. The organism required glutamic acid, thiamine, biotin, magnesium, iron, and potassium for growth. Cells from such a synthetic medium were shown to contain methionine indicating that inorganic sulphur was used. Glutamic acid could not be replaced with glutamine (unheated), aspartic acid, asparagine, nor ammonium salts. The relationship of nutritional requirements of micrococci and staphylococci to classification is discussed.