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M F MALLETTE

Publications and source records attributed to M F MALLETTE.

At least 19 recordsLinked to original sources
PubMed1965

GRINDING MICROORGANISMS WITH A PERISTALTIC PUMP.

The Randolph Co. model 610 peristaltic, (1/8)-hp pump was effective for preparative purposes in disrupting baker's yeast and spores of Bacillus globigii when suspended with glass beads. Best results were obtained with use of a slurry just fluid enough to flow through tubing while stirred. Beads of 0.2 and 0.1 mm were used to best advantage for the yeast cells and spores, respectively. Yeast cells were disrupted completely within 15 min, and the spores in 10 to 30 min. Temperature and surface denaturation are readily controlled, and the system is easily modified for use with large quantities of microorganisms.

Bacillus↗
PubMed1965

PRODUCTION AND PARTIAL PURIFICATION OF ANTIBIOTIC MATERIALS FORMED BY PHYSARUM GYROSUM.

Pure cultures of Physarum gyrosum were grown on agar plates with autoclaved Escherichia coli suspensions as the growth medium. Portions of such agar, after growth of the slime mold, contained diffusible materials that inhibited the growth of Bacillus subtilis, B. cereus, E. coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Paper chromatography of extracts of such cultures revealed at least three different active fractions. Preliminary fractionations increased the specific activity by one order of magnitude, probably in part by removal of inactive material and in part by separating active components. The fractionations also demonstrated the multiplicity of the antibiotic activity. Fractions variously obtained always retarded the growth of the bacterial species listed above.

Anti-Bacterial Agents↗
PubMed1964

GROWTH AND SURVIVAL OF ESCHERICHIA COLI IN MEDIUM LIMITED IN PHOSPHATE.

Mallette, M. F. (Pennsylvania State University, University Park), Cynthia I. Cowan, and J. J. R. Campbell. Growth and survival of Escherichia coli in medium limited in phosphate. J. Bacteriol. 87:779-785. 1964.-Washed suspensions of Escherichia coli B increased in turbidity and plate count when incubated at 36.5 to 38 C without added phosphate. The population increased more quickly than did the turbidity. On continued incubation, cell viability decreased rapidly in the presence of all necessary nutrients except phosphate. The decline in viability was logarithmic for 90% of the death curve, suggesting loss of a single critical process. Various combinations of phosphate-starved cells and log-phase cells with fresh, phosphate-deficient and phosphate-containing media, and medium depleted of any contaminating phosphate suggested that the simple, phosphate-deficient medium was, in fact, devoid of available phosphorus. This deduction was confirmed by the linearity and extrapolation through the origin of a plot of turbidity against inoculum size. Cell suspensions increased in a linear manner, with the phosphate concentration at low levels. Therefore, a threshold requirement of phosphate for growth of E. coli did not exist, at least, above 1 x 10(-9) moles of phosphate per ml. Thus, there is no maintenance level for phosphorus in the organism analogous to the energy of maintenance. When cells had been previously incubated without exogenous phosphate, their subsequent response to added phosphate was limited. Moderate additions of phosphate did not raise the turbidity much above a plateau value reached at lower phosphate concentrations. Under such conditions, the cells were still viable as measured by plate counting. Yet, when returned to a relatively complete but simple medium after starvation, they could not divide normally. Growth of E. coli in a medium deficient only in phosphate rendered the cells susceptible to death on continued incubation. Apparently, material lost during starvation was necessary for multiplication. It was replaced by the plating medium and colonies formed.

Bacteriological Techniques↗
PubMed1962

Inhibition of the tyrosinase oxidation of one substrate by another.

The catalytic oxidation of catechol by crude preparations of mushroom tyrosinase was studied by a method yielding data on initial reaction velocities. Graphical analysis of the results suggests that an excess of catechol inhibits its own oxidation by a competitive process, thus accounting for the observed optimum in the substrate concentration. However, added phenol, though itself a substrate, inhibits the enzymatic oxidation of catechol by a process that is neither competitive nor non-competitive, but a mixture of the two types. Mechanisms of this inhibition of the enzyme by a second substrate are discussed in exploring the problem of substrate-substrate inhibition.

Catechols↗
PubMed1962

Nutritional factors stimulating the formation of lysine decarboxylase in Escherichia coli.

Maretzki, Andrew (Pennsylvania State University, University Park) and M. F. Mallette. Nutritional factors stimulating the formation of lysine decarboxylase in Escherichia coli. J. Bacteriol. 83:720-726. 1962 - Inclusion of complex nitrogen sources in the induction medium was shown to be necessary for the synthesis of appreciable amounts of l-lysine decarboxylase by Escherichia coli B. Hy-case, a commercial acid hydrolyzate of casein, was especially effective in enzyme production, which was assayed manometrically after lysis of the bacteria from without by bacteriophage. Partial fractionation of the Hy-case, identification of the free amino acids, and addition of these amino acids to test media revealed stimulatory effects by methionine, threonine, proline, leucine, and tyrosine. A full complement of amino acids did not match the enzyme levels reached in the presence of Hy-case. Certain peptide fractions obtained from this mixture supplemented the effects of the amino acids in such a way as to suggest direct incorporation of peptide rather than transport or protective roles. Added purines, pyrimidines, iron, and water-soluble vitamins were without effect. Neither carbohydrates nor phosphorylated materials could be detected in the stimulatory fractions.

Amino Acids↗
PubMed1961

The natural occurrence of ethionine in bactdria.

Two unknown radioactive areas appeared after radioautography and two dimensional paper chromatography of culture medium in which Escherichia coli was grown. These materials were studied by paper chromatography and paper electrophoresis of several derivatives and identified as ethionine and ethionine sulfone, the latter an artifact. Chromatographic coincidence of the unknowns and their derivatives with authentic materials establishes the identification. Ethionine was found in cellular extracts and in the growth media of Escherichia coli, Bacillus megaterium, Pseudomonas aeruginosa, and Aerobacter aerogenes but not in Scenedesmus, Saccharomyces cerevisiae, or bovine lymphosarcoma cells. Ethionine was synthesized by resting E. coli cultures from radioactive sulfate and from radioactive methionine. Growing cells labeled ethionine within 1 minute after addition of radioactive sulfate to cultures. Levels of radioactivity in ethionine increased with time. No incorporation of this amino acid could be detected in the cellular proteins formed under the conditions of this study.

Animals↗
PubMed1961

The effect of exogenous energy sources on the synthesis of beta-galactosidase in resting-cell suspensions of Escherichia coli.

Using methyl-1-thio-beta-D-galactoside as the inducer, the biosynthesis of beta-galactosidase was observed in Escherichia coli B with only endogenous sources of nitrogen and energy available. The addition of glucose, ribose, xylose, or glycerol as exogenous energy sources to nitrogen-deficient media blocked enzyme formation. Preinduction of the resting cells failed to overcome inhibition by the added energy sources. With limited quantities of glucose, ribose, xylose, or glycerol, synthesis of beta-galactosidase resumed abruptly and continued at the rate normal for cells in nitrogen-deficient media. Comparison of enzyme activities with oxygen uptake data revealed a reduction in the rate of oxygen uptake at the time enzyme synthesis resumed in media originally containing small amounts of energy sources. This change corresponded to only a fraction of the oxygen required for complete oxidation of one of the exogenous substrates. It is suggested that inhibition by these particular exogenous substrates involves metabolism to a common repressor or interference with an energy-transfer system.

Escherichia coli↗
PubMed1959

Enzyme biosynthesis in Escherichia coli.

Escherichia coli B synthesized beta-galactosidase and an enzyme system for D-xylose when exposed to lactose and xylose respectively in nitrogen-free media. The amount of beta-galactosidase formed in the absence of external nitrogen depended upon the nature of the medium in which the cells had originally been grown. Half as much of this enzyme was synthesized without exogenous nitrogen by cells taken from a nitrogen-rich medium as was formed by cells under favorable conditions with an external supply of nitrogen. Escherichia coli B contained a pool of nitrogen compounds soluble in 80 per cent ethanol and made up of several ninhydrin-positive components. One of these was identified chromatographically as glycine using an authentic radioactive sample. Another substance behaved like serine on the chromatograms. The internal pool of amino acids and peptides was large enough to account for the beta-galactosidase synthesized by cells exposed to lactose in a medium free of nitrogen. Some degree of interaction of the syntheses of the beta-galactosidase and xylose enzyme systems was observed in nitrogen-free media. This interaction produced a greater effect on the formation of beta-galactosidase and was attributed to a limiting factor(s) in the internal nitrogenous pool or to a limiting intermediate in enzyme synthesis.

Enzymes↗