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At least 127 records · Page 7Linked to original sources
PubMed1961

Evidence for the de novo synthesis of the alpha-amylase of Pseudomonas saccharophila.

Eisenstadt, Jerome M. (Brandeis University, Waltham, Mass.) and Harold P. Klein. Evidence for the de novo synthesis of the alpha-amylase of Pseudomonas saccharophila. J. Bacteriol. 82:798-807. 1961.-Chloramphenicol at a concentration of 20 mug per ml inhibited the appearance of the inducible alpha-amylase of Pseudomonas saccharophila. This inhibition was observed when induction was attempted in buffer or in a complete medium. Preinduced cells were also prevented from forming this enzyme under similar conditions. Under all the conditions tested, there was no lag in chloramphenicol inhibition, thus suggesting an absence of any protein precursor in amylase formation. Cells suspended in a complete medium without a nitrogen source lost their capacity to form this enzyme when subsequently induced in buffer. When cells were grown in the presence of radioactive sulfate and then subjected to starvation, the radioactivity of the amino acid pool diminished only slightly. However, examination of the free amino acid pool by paper chromatography showed that the loss of enzyme inducibility was accompanied by the disappearance of glutamine, aspartic acid, and a third, unidentified, compound. Enzyme-forming ability was restored by the addition, to starved cells of casein hydrolysate, glutamate, glutamine, or aspartate. Other amino acids tested were ineffective in this regard. When cells were induced in buffer in the presence of labeled methionine, amylase was formed at a linear rate over a 3-hr period. Furthermore, both the cellular proteins and the extracellular amylase became labeled at a linear rate. These observations are discussed in relation to the problem of protein turnover, and are interpreted as evidence for the de novo synthesis of alpha-amylase in this organism.

Amino Acids↗
PubMed1962

Nutritional requirements for Hydrogenomonas eutropha.

Repaske, Roy (National Institute of Allergy and Infectious Diseases, Bethesda, Md.). Nutritional requirements for Hydrogenomonas eutropha. J. Bacteriol. 83: 418-422. 1962.-A simple apparatus for the autotrophic cultivation of Hydrogenomonas eutropha in 100-ml shake cultures is described. Nitrogen, in the form of ammonium, nitrate, or urea, was used for growth; nitrite could not be utilized. Optimal growth occurred at pH 6.4 to 6.8 at 30 C. H. eutropha grew best in an atmosphere containing 15 to 25% oxygen and 10% carbon dioxide. Below these concentrations each of the gases was limiting. Growth was shown to be dependent on iron, and the rate of growth was a function of iron concentration and its state of oxidation.

Carbon Dioxide↗
PubMed1963

QUANTITATIVE STUDIES OF THE EFFECT OF ORGANIC SUBSTRATES AND 2,4-DINITROPHENOL ON HETEROTROPHIC CARBON DIOXIDE FIXATION IN HYDROGENOMONAS FACILIS.

McFadden, Bruce A. (Washington State University, Pullman), and H. Robert Homann. Quantitative studies of the effect of organic substrates and 2,4-dinitrophenol on heterotrophic carbon dioxide fixation in Hydrogenomonas facilis. J. Bacteriol. 86:971-977. 1963.-Whole cells of Hydrogenomonas facilis under heterotrophic conditions fixed levels of C(14)O(2) which depended upon the nature of the carbon source being oxidized. It was established that oxidative rates varied as a function of p(CO2). Therefore, all studies were conducted in the presence of 1.5 mole% CO(2) in the gas phase. With glucose-grown cells supplied with glucose as substrate, the heterotrophic fixation was curtailed 98% by the addition of 8.3 x 10(-4)m 2,4-dinitrophenol (DNP). A coupling between reductive fixation of CO(2) and heterotrophic oxidation of substrate is consistent with the observed effect of DNP. The efficiency of coupling of fixation with oxidation was studied for acetate, d-glucose, l-glutamate, d,l-lactate, d-ribose, and succinate as substrates. Kinetic studies showed that the efficiency of coupling (expressed as disintegrations per minute of C(14) per microliter of O(2)) was initially time-variable for all substrates; however, it approached a constant value after 30 to 45 min for acetate, glutamate, lactate, and succinate. The initial variation of the ratio with time was due primarily to C(14)O(2) uptake, which was nonlinear with time. Control studies in the absence of exogenous substrate indicated that CO(2) fixation may also be linked to oxidation of endogenous stores accumulated during heterotrophic growth. d-Ribose appears to be the most promising substrate for short-term fixation studies owing to the rapid incorporation of C(14) and the unusually low endogenous fixation rate by cells grown on ribose. Calculations reveal that, after isotopic equilibrium has occurred, the amount of CO(2) utilized during glucose oxidation is almost 50% of O(2) uptake during the same interval. Even during succinate oxidation, which was shown to be coupled much less effectively with CO(2) fixation, the CO(2) utilized during the same interval is 8% of O(2) uptake.

2,4-Dinitrophenol↗
PubMed1963

BIOSYNTHESIS OF RIBOSE AND DEOXYRIBOSE IN PSEUDOMONAS SACCHAROPHILA.

Fossitt, Dexter D. (University of Michigan, Ann Arbor), and I. A. Bernstein. Biosynthesis of ribose and deoxyribose in Pseudomonas saccharophila. J. Bacteriol. 86:1326-1331. 1963.-The biosynthesis of ribose and deoxyribose in Pseudomonas saccharophila was studied by radioisotope-tracer techniques. Patterns of C(14) in ribose isolated from the nucleic acids of cells grown on labeled glucose suggested that pentose was made by the pathway involving transaldolase and transketolase. When cells were grown on radioactive gluconate, the tracer patterns indicated the possibility of a new pathway for the biosynthesis of ribose. Isotopic patterns in deoxyribose, in general, were consistent with the pathway involving reduction of ribonucleotides to deoxyribonucleotides. Certain aspects of the data, however, were not explained by this known pathway.

Carbohydrate Metabolism↗