bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of Staphylococcal Enterotoxin B Formation by Cell Wall Blocking Agents and other Compounds
Authors: Friedman Mischa E.
Published: January 2020

Enterotoxin B formation by
Staphylococcus aureus
S6 was inhibited by Tween 80, oleic acid, sodium deoxycholate, penicillin,
d
-cycloserine, or bacitracin. Toxin formation by strain 243 was sensitive to oleic acid, sodium deoxycholate, sodium lauryl sulfate,
d
-cycloserine, or bacitracin. The effect of
d
-cycloserine was reversed by
d
-alanine with strain 243 but not with strain S6. Neither penicillin nor bacitracin inhibited α-hemolysin or coagulase activity of strain S6; however, 0.118 μmoles of
d
-cycloserine per ml increased the α-hemolysin titer more than eightfold. Pigmentation of strain 243 was reduced by oleic acid, sodium deoxycholate, or methicillin, and was completely inhibited by
d
-cycloserine or bacitracin. Glucose was required for the inhibition by spermine of
14
C-valine incorporation into cellular protein of strain S6. These data indicate that the cell surface may contain sites important to the synthesis of enterotoxin B.
Osmotic Remedial Response in a Galactose-negative Mutant of
Saccharomyces cerevisiae
Authors: Bassel John , Douglas H. C.
Published: January 2020

We investigated an osmotic remedial mutant of
Saccharomyces
which was deficient in galactose-1-phosphate uridyl transferase. Both the rate of growth and the transferase activity of the mutant culture were dependent on the osmotic activity of the growth medium. Organic and ionic solutes proved to be equally effective in inducing the osmotic remedial response. The galactose pathway enzymes were separable by ultracentrifugation, indicating that a stable interenzyme complex was not formed. The results were consistent with the hypothesis that the corrective effect occurs at the tertiary or quaternary level of organization in an environmentally sensitive protein. The possibility that the osmotic remedial response represents an effect of translation is discussed.
Accumulation in Gram-positive and Gram-negative Bacteria as a Mechanism of Resistance to Erythromycin
Authors: Mao James C.-H. , Putterman Mary
Published: January 2020

Erythromycin was recovered in high yield after incubation with gram-negative bacteria. The cell-free protein-synthesizing preparation from gram-negative bacteria is equally as susceptible to the antibiotic as is that from gram-positive bacteria. Thus, neither destruction of erythromycin nor the absence of the step susceptible to the antibiotic plays an important role in the resistance mechanism of gram-negative bacteria. A 100-fold difference in accumulation of erythromycin between gram-positive and gram-negative bacteria was observed. This alone explains the resistance of gram-negative bacteria to erythromycin. Furthermore, data showed that the inhibition of growth is closely related to the accumulation of erythromycin. The concentration of intracellular erythromycin in gram-positive bacteria was found to be 44- to 90-fold greater than that of the extracellular medium. However, the antibiotic did not accumulate on the cell walls, nor was the accumulation energy-dependent. It is proposed that it takes place by the binding of erythromycin to the bacterial ribosomes, forming a very stable complex. The dissociation constants of erythromycin-
Staphylococcus aureus
complex and erythromycin-
Bacillus subtilis
complex were determined to be 1.1 × 10
−7
and 3.4 × 11
−7
m
, respectively.
Interaction of Staphylococcal α-Toxin with Artificial and Natural Membranes
Authors: Freer John H. , Arbuthnott John P. , Bernheimer Alan W.
Published: January 2020

Comparison of hemolytic activity and chromate-releasing activity of partially purified preparations of staphylococcal α-toxin indicated the presence of a lytic factor other than α-toxin. This lytic release factor (RF) was isolated from the preparations and was shown to be active against both lipid spherules and erythrocytes. Heat-purified α-toxin (HP α-toxin) disrupted spherules, with the formation of fragments which always showed the presence of ring structures similar in dimensions (ca. 90 A) to pure α 12
S
-toxin. The interaction of HP α-toxin with spherules was accompanied by loss of hemolytic activity and adsorption of toxic protein. The α 12
S
-toxin, although only weakly hemolytic, was shown to be lytic for spherules. An α 12
S
-free toxin rapidly disrupted spherules, with formation of fragments with attached rings similar in dimensions to the α 12
S
molecule. Lipid monolayer experiments showed that HP α-toxin could penetrate lipid monolayers by virtue of a hydrophobic interaction. Effects of HP α-toxin on rabbit and human erythrocyte ghosts were similar to its effects on spherules, in that rings appeared on membrane fragments. Toxin-lysed rabbit erythrocytes showed similar rings on the resulting membrane fragments. However, rings were not seen on toxin-treated rabbit erythrocytes in the prelytic lag phase; this result and the fact that human erythrocytes are largely insensitive to α-toxin were interpreted as evidence against a lytic mechanism involving ring formation as the primary event. Rings were interpreted as toxin polymers similar to α 12
S
molecules, formed from specifically orientated active toxin molecules at the surface of lipid structures. Possible mechanisms for toxin lysis of spherules and erythrocytes are discussed.
Nature of the Complementation Products Formed by a Complementing Mutant of
Neurospora crassa
Authors: Sundaram T. K. , Fincham J. R. S.
Published: January 2020

The mutant
am-14
produces no active nicotinamide adenine dinucleotide phosphate-linked glutamate dehydrogenase (GDH) and no protein showing immunological cross-reaction with the enzyme. Nevertheless, it shows complementation with several other
am
mutants in heterokaryons. Active GDH can be extracted from heterokaryons formed from
am-14
and other mutants which, by themselves, produce more or less inactive varieties of the enzyme. The enzyme from
am-14
+
am-3
heterokaryons can be partially separated from
am-3
mutant GDH on a diethylaminoethyl cellulose column. It is characterized by abnormally high thermolability and by a capacity for activation by glutamate. By the same procedure as brings about hybridization between mutant GDH proteins, it has been possible to recover enzyme with the properties of pure
am-3
GDH from a partially purified
am-14
+
am-3
GDH preparation which was initially substantially free of unhybridized
am-3
enzyme. This is interpreted as evidence that the active complementation product is a hybrid oligomer containing
am-3
monomers and also
am-14
monomers, the latter being unable to aggregate by themselves. Heterokaryons formed from
am-14
and wild type produce GDH of abnormally high thermolability, presumably due to the formation of
am-14
+
am
+
hybrids.
Regulation of Pyrimidine Biosynthesis in
Saccharomyces cerevisiae
Authors: Lacroute Francois
Published: January 2020

Biochemical steps of the pyrimidine pathway have been found to be the same in yeast as in bacteria, and all except one step have been characterized. The activities of the first two enzymes, carbamoyl phosphate synthetase and aspartic transcarbamylase, are simultaneously controlled by feedback inhibition and repression. Moreover, these enzymes are coded by the same genetic region (
ura-2
) and seem to form a single enzymatic complex. The enzymes that follow later in the pathway are induced in a sequential way by the intermediary products and are insensitive to pyrimidine repression. The corresponding genes (
ura-4, ura-1, ura-3
) are not linked to each other or to
ura-2
, the gene for carbamoyl phosphate synthetase and aspartic transcarbamylase. Mutants that have simultaneously lost feedback inhibition by uridine triphosphate for carbamoyl phosphate synthetase and for aspartic transcarbamylase have been found and mapped in the gene
ura-2
.
Regulation of Pentitol Metabolism by
Aerobacter aerogenes
I. Coordinate Control of Ribitol Dehydrogenase and
d
-Ribulokinase Activities
Authors: Bisson Theresa M. , Mortlock Robert P.
Published: January 2020

Induction studies on
Aerobacter aerogenes
strain PRL-R3, using ribitol as the inducer-substrate, indicated that two enzymes of ribitol catabolism, ribitol dehydrogenase and
d
-ribulokinase, are coordinately induced. The utilization of
d
-arabinose as a substrate resulted in the induction of ribitol dehydrogenase as well as
d
-ribulokinase. Mutants which were constitutive for ribitol dehydrogenase were also constitutive for
d
-ribulokinase. In contrast,
d
-xylulokinase and
d
-arabitol dehydrogenase did not appear to be coordinately controlled. Induction studies and examination of
d
-arabitol dehydrogenase constitutive mutants indicated that the three enzymes of the converging pathways for
d
-arabitol and
d
-xylose catabolism are under separate control.
Regulation of Pentitol Metabolism by
Aerobacter aerogenes
II. Induction of the Ribitol Pathway
Authors: Bisson Theresa M. , Oliver Eugene J. , Mortlock Robert P.
Published: January 2020

The incubation of
Aerobacter aerogenes
PRL-R3 with ribitol resulted in the induction of ribitol dehydrogenase and
d
-ribulokinase, coordinately controlled enzymes of the pathway of ribitol catabolism. A dehydrogenase-negative mutant was unable to induce
d
-ribulokinase activity following incubation with ribitol. Similar experiments using a kinase-negative mutant resulted in normal induction of ribitol dehydrogenase, as compared to the wild-type PRL-R3 strain. Constitutive or induced cells for
l
-fucose isomerase were capable of catalyzing the isomerization of
d
-arabinose to
d
-ribulose. In contrast to the experiments using ribitol as the substrate, the isomerization of
d
-arabinose resulted in the induction of
d
-ribulokinase with dehydrogenase-negative cells. These data indicated that
d
-ribulose, rather than ribitol, acts as the inducer of the enzymes for ribitol degradation.
Microbial Degradation of Corrinoids VI. Reduction of Hydroxocobalamin by Cell-free Particles fromPseudomonas rubescens
Authors: Hufham J. B. , Burgus R. C. , Ing Sandra Y. S. , Pfiffner J. J.
Published: January 2020

Cell-free particles fromPseudomonas rubescenshave been shown to reduce hydroxocobalamin to vitamin B12r. The particles are unable to reduce the B12rto B12s. The reduction of hydroxocobalamin is dependent upon reduced nicotinamide adenine dinucleotide and is stimulated by flavin adenine dinucleotide. Cobinamide and diaquocobinamide were reduced at 25 and 10%, respectively, of the rate of hydroxocobalamin. Cyanocobalamin, coenzyme B12, pseudovitamin B12, and diaquopseudocobalamin were not reduced. Reduced nicotinamide adenine dinucleotide phosphate and flavin mononucleotide were not active. Diaphorase and xanthine oxidase activity were not present in the particulate fraction.
Effect of Structural and Stereochemical Methylproline Isomers on Actinomycin Biosynthesis
Authors: Yoshida Tadashi , Mauger Anthony , Weissbach Herbert , Katz Edward
Published: January 2020

The inhibitory effect of methylprolines on actinomycin biosynthesis by
Streptomyces antibioticus
was studied; the order of effectiveness was 3- >4- >5-methyl-
dl
-proline.
Cis
-3-methyl-
dl
-proline was 14 times more active than the
trans
isomer. It was also found that 4- and, possibly, 5-methylproline were incorporated into the actinomycin molecule. When 4-methylproline was present, three new actinomycins, representing 50 to 60% of the antibiotic mixture, were synthesized. Growth of the organism may be stimulated at concentrations (0.1 to 1.0 μg per ml) of 3-methylproline that inhibit antibiotic formation, thus providing additional evidence for a different mechanism of actinomycin synthesis from that of protein synthesis. Azetidine-2-carboxylic acid, piperdine-2-carboxylic acid, and hydroxyproline (but not sarcosine) reversed the inhibition due to 3-methylproline.
Tryptophan Transport in
Neurospora crassa
II. Metabolic Control
Authors: Wiley W. R. , Matchett W. H.
Published: January 2020

The rate of tryptophan transport in
Neurospora
is regulated by the intracellular pool of tryptophan. When cells were shifted from growth in minimal medium to tryptophan-containing medium for 10 min, there was a 50% reduction in the rate of tryptophan transport. Intracellular tryptophan pools derived from indole were equally effective in reducing the rate of transport as externally supplied tryptophan. The regulatory influence of tryptophan on the transport system appears to be a property of all the amino acids transported by the tryptophan transport site or sites. Lysine and glutamic acid are not transported by the tryptophan transport site or sites and are ineffective in the regulation of tryptophan uptake. Continued protein synthesis is required for the maintenance of a functional tryptophan transport system. The half-life of the transport system, estimated by inhibiting protein synthesis with cycloheximide, was about 15 min. Turnover of the system occurred at 30 C but not at 4 C, suggesting that the breakdown of the system is enzymatically mediated. It was inferred that the rate of tryptophan transport in
Neurospora
is modulated through the maintenance of a delicate balance between the synthesis and breakdown of some component of the transport system.
Phosphomannanase (PR-Factor), an Enzyme Required for the Formation of Yeast Protoplasts
Authors: McLellan William L. , Lampen J. Oliver
Published: January 2020

The PR-factor, an enzyme necessary for the production of protoplasts from yeast, was identified and was named phosphomannanase. The enzyme released mannan and mannan-proteins from yeasts harvested in the logarithmic phase of growth. The size of the molecules released was greater than 200,000 daltons, which indicated that the enzyme splits very few bonds of the yeast wall. The PR-factor also depolymerized phosphomannans produced by the
Hansenula
species. The degradation of these substances was due to the splitting of mannosidic bonds. However, the phosphodiester bonds present in these phosphomannans were involved in the specificity of the enzyme, and the number of mannosidic bonds cleaved was dependent on the number of phosphodiester bonds present. We studied the products of degradation of
Hansenula
phosphomannans and were unable to identify the exact bond split by the enzyme. After enzymatic digestion and subsequent splitting of phosphodiester bonds, phosphomannan Y-2448 yielded products too complex to be separated. Phosphomannan Y-1842 was shown to have a structure more complex than that previously proposed. The action of the enzyme on the phosphate-rich walls of
Saccharomyces
was studied. Mannan, containing intact phosphodiester bonds, was released from the walls. Mild acid hydrolysis of this released material split the diester bonds to yield monosaccharide and polysaccharide terminated in mannose-6-phosphate. From these products, we deduced that the enzyme cleaved a mannosidic bond adjacent to a mannose, which is also phosphodiester linked through carbon 1. The significance of phosphodiester bonds in the attachment of mannan and mannan-protein enzymes to the wall of yeast is discussed.
Separation of Bacterial Ribosomal Ribonucleic Acid from Its Macromolecular Precursors by Polyacrylamide Gel Electrophoresis
Authors: Hecht Norman B. , Woese Carl R.
Published: January 2020

Electrophoresis on polyacrylamide gels was found to be a powerful technique for separating the mature from the precursor forms of bacterial ribosomal nucleic acid (rRNA). The separation of the 16
S
rRNA from its precursor was, for all practical purposes, complete; that of the 23
S
rRNA from its precursor was detectable but incomplete. When mature and precursor rRNA preparations were heated to randomize secondary structure, etc., and then cooled, it was found that electrophoretic mobility differences between mature forms of rRNA and their precursors persisted. This, in conjunction with the rather large electrophoretic mobility differences between mature and precursor forms, can be taken as strong evidence for a molecular weight difference between mature rRNA and its precursor forms of RNA. With the 16
S
rRNA, this difference could be as large as 130,000 daltons.
Role of Tryptophan Pyrrolase in Endotoxin Poisoning
Authors: Moon Robert J. , Berry L. Joe
Published: January 2020

Using substrate induction as a tool, we attempted to determine the role of tryptophan pyrrolase in the response to endotoxin in mice. Previous results have shown that the administration of the
ld
50
of endotoxin lowers tryptophan pyrrolase activity. α-Methyltryptophan was found to maintain tryptophan pyrrolase activity above control levels in endotoxin-poisoned mice without increasing survival. 5-Hydroxytryptophan, by contrast, lowered tryptophan pyrrolase activity but did not sensitize mice to endotoxin. These results suggest that tryptophan pyrrolase per se does not play a unique role in survival of mice poisoned with endotoxin. This enzyme, however, may reflect the fate of other liver enzymes inducible by adrenocorticoids. In mice given concurrent injections of tryptophan and endotoxin, tryptophan pyrrolase activity was elevated to a level intermediate between that of normal mice and that of mice given tryptophan alone. The mice injected with tryptophan and endotoxin also had about the same mortality as mice given endotoxin alone. Mice treated with tryptophan 4 hr after endotoxin, at a time when the substrate did not fully elevate tryptophan pyrrolase activity, died convulsively and in larger numbers than those given endotoxin alone. This effect was reversed by prior treatment with cyproheptadine, an antiserotonin drug. These results indicate that the depression of tryptophan pyrrolase activity previously observed in vitro after injection of endotoxin reflects an actual decrease in the in vivo activity of the enzyme.
Mutants of
Escherichia coli
with an Altered Tryptophanyl-Transfer Ribonucleic Acid Synthetase
Authors: Doolittle W. Ford , Yanofsky Charles
Published: January 2020

Fourteen mutant strains of
Escherichia coli
were examined, each of which requires tryptophan for growth but is unaltered in any of the genes of the tryptophan biosynthetic operon. The genetic lesions responsible for tryptophan auxotrophy in these strains map between
str
and
malA
. Extracts of these strains have little or no ability to charge transfer ribonucleic acid (tRNA) with tryptophan. We found that several of the mutants produce tryptophanyl-tRNA synthetases which are more heat-labile than the enzyme of the parental wild-type strain. Of these heat-labile synthetases, at least one is protected against thermal inactivation by tryptophan, magnesium, and adenosine triphosphate. Two other labile synthetases which are not noticeably protected against heat inactivation by substrate have decreased affinity for tryptophan. On low levels of supplied tryptophan, these mutants exhibit markedly decreased growth rates but do not contain derepressed levels of the tryptophan biosynthetic enzymes. This suggests that the charging of tryptophan-specific tRNA is not involved in repression, a conclusion which is further substantiated by our finding that 5-methyltryptophan, a compound which represses the tryptophan operon, is not attached to tRNA by the tryptophanyl-tRNA synthetase of
E. coli
.
Intracellular Distribution of
3
H-Dihydrostreptomycin in a Streptomycin-dependent Strain of
Bacillus megaterium
Authors: Wolfgang R. W. , Lawrence N. L.
Published: January 2020

The cells of a streptomycin-dependent strain of
Bacillus megaterium
took up only 2 to 5% of the dihydrostreptomycin present in the medium when grown in the minimum concentration of streptomycin required for growth. During growth in the presence of
3
H-dihydrostreptomycin, radioactivity was accumulated intracellularly in three forms, namely, unbound, loosely bound to the ribosomes (removable by dialysis), and tightly bound to the ribosomes (retained after prolonged dialysis). More radioactivity for a given amount of ribonucleic acid was bound by ribosomes attached to the cell membrane than by supernatant ribosomes. Of the nondialyzable radioactivity associated with isolated ribonucleic acid, 40 to 60% was solubilized by treatment with ribonuclease or by dilute alkaline hydrolysis.
Effect of Folinate on Thymidine Uptake by
Pediococcus cerevisiae
Authors: Mandelbaum-Shavit Frederika , Grossowicz Nathan
Published: January 2020

Uptake of
3
H-thymidine by resting cells of
Pediococcus cerevisiae
was found to be energy- and temperature-dependent. The
p
H optimum was between 6.5 and 8.0, and after 2 min of incubation most of the radioactivity was found in the deoxyribonucleic acid (DNA) fraction. Iodoacetate at a concentration of 10
−2
m
caused a 50% inhibition of uptake. Preincubation of resting cells for 10 min with folinate (10
−3
μ mole/ml) diminished the
3
H-thymidine uptake by 75%. In growing cells, the folinate-induced inhibition was still more striking. Deoxyuridine augmented the folinate effect, whereas fluorodeoxyuridine and aminopterin or amethopterin abolished it. Preincubation with folinate did not interfere with the uptake of
3
H-amethopterin, and thus the inhibitor did not compete for uptake sites within the cell. The role of these inhibitors in reversing the folinate effect is discussed. Cells preincubated with folinate showed an increased incorporation of
14
C-uracil into DNA, presumably after prior conversion to thymidylate. We concluded that the folinate effect was due to stimulation of de novo thymidylate synthesis with concomitant inhibition of the uptake of external thymidine.
Association of C-reactive Protein and Circulating Leukocytes with Resistance to
Staphylococcus aureus
Infection in Endotoxin-treated Mice and Rabbits
Authors: Patterson L. T. , Harper J. M. , Higginbotham R. D.
Published: January 2020

The response of rabbits and mice to treatment with
Escherichia coli
endotoxin, as measured by C-reactive protein (CRP) and leukocyte levels, and resistance to
Staphylococcus aureus
infection was studied to evaluate the significance of these responses and their associations. In both species, there was an initial leukopenia without early recovery of normal lymphocyte levels. This was followed by an increase in polymorphonuclear leukocytes and a return to near the normal range. The CRP level was slightly altered during the stage of decreased resistance and increased throughout the remainder of the period of observation. The resistance level was decreased initially, recovered to normal levels, and continued to increase. The changes in CRP and resistance levels were closely associated. It would appear that this association between CRP and resistance, the antibacterial activity of CRP, and its action on the polysaccharides obtained from bacterial cell walls are evidence for the participation of CRP in nonspecific resistance to infection.
Enzyme and Nucleic Acid Formation During Synchronous Growth of
Rhodopseudomonas spheroides
Authors: Ferretti Joseph J. , Gray Ernest D.
Published: January 2020

The synthesis of various cell components was examined during the anaerobic photosynthetic growth of synchronous populations of
Rhodopseudomonas spheroides
. Net deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein increased continuously as did the rate of incorporation of radioactive precursors into protein. The rates of incorporation of radioactive precursors into RNA and DNA were marked by abrupt discontinuities. It is not clear whether these discontinuities represent changes in rates of synthesis or fluctuations in precursor pools. Although the synthesis of bacteriochlorophyll occurred in a continuous manner, those enzymes examined which are involved in the synthesis of tetrapyrroles, i.e., succinyl CoA thiokinase, δ-aminolevulinic acid synthetase, and δ-aminolevulinic acid dehydrase, increased discontinuously. Two other enzymes not involved in tetrapyrrole biosynthesis were examined. Alkaline phosphatase increased in a stepwise manner during the division cycle, whereas the synthesis of ornithine transcarbamylase increased rapidly before leveling off for a period of time until synthesis began again. In each instance of discontinuous enzyme synthesis, increases occurred at regular and characteristic times during the division cycle. Ammonium sulfate precipitation was employed to remove low molecular weight end product inhibitors from enzyme preparations. These studies suggested that the stepwise increases in enzyme activity observed in the present investigation were not affected by periodic end product inhibition. A temporal map of enzyme synthesis during the division cycle was constructed. Both δ-aminolevulinic acid synthetase and δ-aminolevulinic acid dehydrase appeared early in the division cycle, whereas alkaline phosphatase and succinyl CoA thiokinase appeared later on.
Purification and Properties of
Mucor pusillus
Acid Protease
Authors: Somkuti G. A. , Babel F. J.
Published: January 2020

The protease produced by
Mucor pusillus
was recovered from a wheat bran medium by treatment with ammonium sulfate, ethyl alcohol, gel filtration and ion-exchange chromatography. The yield of the enzyme was 55%. The overall increase in the specific activity of the protease was 34-fold. The purified protease was most active at
p
H 3.8 and 5.6 against hemoglobin and casein, respectively. Optimal hydrolysis of casein was observed at 55 C. The enzyme was stable from
p
H 3.0 to 6.0. Enzyme inactivated by metal ions was reactivated by ethylenediaminetetraacetate and
o
-phenanthroline. Reducing agents and thiol poisons had no effect on the protease, suggesting that free sulfhydryl groups were not required for enzyme activity. Diisopropyl fluorophosphate did not inhibit the protease, indicating the probable absence of serine in the active center. The Michaelis-Menten constant for casein was 0.357%. Electrophoretic analysis of active protein recovered by ion-exchange chromatography showed that the protease preparation was homogeneous.
Oxidation of
d
-Amino Acids by a Particulate Enzyme from
Pseudomonas aeruginosa
Authors: Marshall Vincent P. , Sokatch John R.
Published: January 2020

A particulate
d
-amino acid dehydrogenase has been partially purified from cell free extracts of
Pseudomonas aeruginosa
grown on
dl
-valine as the source of carbon and energy. A standard assay was developed which utilized 2,6-dichlorophenol-indophenol as the electron acceptor. The
p
H optimum for enzyme activity ranged from 6.0 to 8.0, depending on the amino acid assayed. The enzyme was most active with monoamino-monocarboxylic amino acids and histidine. The Michaelis constant for
d
-phenylalanine was found to be 1.3 × 10
-3
m d
-phenylalanine. Constants could not be calculated for the other amino acids oxidized because anomalous plots of
V
as a function of
V/S
were obtained. Spectra of enzyme preparations reduced with
d
-valine or sodium hydrosulfite exhibited adsorption bands typical of the α, β, and γ bands of cytochromes as well as bleaching in the flavin region of the spectrum. When
dl
-valine was added to a medium with glycerol as the energy source,
d
-amino acid dehydrogenase was detected after the addition of valine and was produced at a rate directly proportional to the synthesis of total protein. The enzyme was formed when
d
-valine,
l
-valine, or
dl
-alanine was the source of carbon and energy, but not when glucose, glycerol, or succinate was the energy source.
Relation of Catalase to Substrate Utilization by
Mycoplasma pneumoniae
Authors: Low I. E. , Eaton M. D. , Proctor P.
Published: January 2020

No catalase activity was detected in four strains of glucose-grown
Mycoplasma pneumoniae
at any time during the replication of the organism. Exogenous catalase dramatically increased the O
2
uptake with glycerol, presumably by releasing inhibition caused by hydrogen peroxide. The effect of added catalase on the O
2
uptake of washed organisms with glucose as substrate was moderate and variable in degree. The production of hydrogen peroxide was demonstrated by the quantitative enzymatic assay for inorganic peroxide and by the fact that added pyruvate, which is non-enzymatically oxidized by H
2
O
2
to acetic acid and CO
2
could mimic the action of catalase.
Analysis of Sporulation Mutants II. Mutants Blocked in the Citric Acid Cycle
Authors: Fortnagel Peter , Freese Ernst
Published: January 2020

Sporulation mutants that were unable to incorporate uracil during the developmental period recovered this capacity with the addition of ribose and in most cases with the addition of glutamate. Of the mutants that responded to both ribose and glumate, all but three also responded to citrate, and all but five responded to acetate. One of the exceptional strains was deficient in aconitase and another one in aconitase and isocitrate dehydrogenase; both required glutamate for growth. For the mutants which did not respond to glutamate, the products made from
14
C-glutamate were determined by thin-layer chromatography. Significant differences were found which enabled the identification of mutant blocks. The deficiency of the corresponding enzyme activity was verified. Several mutants were deficient in α-ketoglutarate dehydrogenase, and one lacked succinic dehydrogenase. These mutants could still grow on glucose as sole carbon source, but not on glutamate. The intact Krebs cycle is therefore not required for vegetative growth of aerobic
Bacillis subtilis
, but it is indispensable for sporulation.
Effects of Salts on the Halophilic Alga
Dunaliella viridis
Authors: Johnson Mary K. , Johnson Emmett J. , MacElroy Robert D. , Speer Henry L. , Bruff Barbara S.
Published: January 2020

Determinations of the salt sensitivity of enzymes extracted from the halophilic alga
Dunaliella viridis
revealed that pentose phosphate isomerase, ribulose diphosphate carboxylase, glucose-6-phosphate dehydrogenase, and phosphohexose isomerase were inhibited by NaCl concentrations far lower than that in the growth medium (3.75
m
). The inhibition was reversible and was not prevented by preparing the extracts in the presence of salt. Potassium, lithium, and cesium chlorides were equally inhibitory. In contrast, whole cells require rather high levels of NaCl for optimal growth, whereas growth is inhibited by low levels of the other cations. The results suggest a specific mechanism for the exclusion of sodium from the interior of the cell.
Thiol-Group Binding of Zinc to a β-Lactamase of
Bacillus cereus:
Differential Effects on Enzyme Activity with Penicillin and Cephalosporins as Substrates
Authors: Sabath Leon D. , Finland Maxwell
Published: January 2020

Zinc, which is required for the hydrolysis of cephalosporins by a crude enzyme from
Bacillus cereus
569, also increased the stability of this activity during storage. A loss in activity of the zinc-activated enzyme which occurred on prolonged hydrolysis of cephalosporin C was not restored by further addition of zinc. The thiol reagents
N
-ethyl maleimide (NEM), iodoacetic acid (IAA), CdCl
2
, and
p
-chloromercuribenzoate, all at 10
−3
m
, and iodine at 1.6 × 10
−3
n
prevent zinc activation of the “cephalosporinase” activity. However, NEM and IAA have minimal or no demonstrable inhibitory effect if the enzyme is first treated with zinc. This suggests that zinc is linked to the apoenzyme by a thiol group. Activation by zinc is only partially prevented by NEM if the crude enzyme is pretreated with nickel, which alone causes negligible activation of the apoenzyme. The order of affinities of these metals for the apparent thiol group is thus Hg
++
, Cd
++
> Zn
++
> Ni
++
. The “cephalosporinase” inhibition by Hg
++
was reversible with dithiothreitol. These metals and thiol reagents do not decrease the ability of the crude enzyme to hydrolyze benzylpenicillin, which is consistent with the report that purified “penicillinase” from
B. cereus
contains no cysteine residue. This suggests that the β-lactamases of
B. cereus
that hydrolyze penicillin and cephalosporins differ from each other by at least one amino acid (cysteine).
Possible Origin of the High Incidence ofClostridium botulinumType E in an Inland Bay (Green Bay of Lake Michigan)
Authors: Bott Thomas L. , Johnson Jodie , Foster E. M. , Sugiyama H.
Published: January 2020

Bottom and shoreline sediments of Green Bay, northern Lake Michigan, and rivers of the Green Bay drainage basin, as well as soils of the surrounding land mass, were examined forClostridium botulinumtype E. Detection was based on identification of type E toxin in enrichment cultures and was influenced by many factors. Testing smaller amounts of sample in multiple cultures was more productive than examining large inocula in fewer cultures. Incubation at 30 C was unsatisfactory, but 14 days at 20 C or 7 days at 25 C gave good results. Mild heating (60 C for 30 min) of specimens reduced the incidence of positive findings. Freezing enrichment cultures prior to testing for toxicity eliminated many nonbotulinal toxic substances that killed mice. A control culture inoculated with type E spores was employed to show whether a specimen contained factors which could mask the presence of type E. Samples from 708 stations were tested in 2,446 cultures. Type E was found in nearly all underwater specimens of Green Bay and northern Lake Michigan but was present less frequently in samples taken along their shores. The incidence was still lower in the rivers emptying into Green Bay with the organism being rare on the shores of these rivers and in the soils of the land mass proper. Samples from the upper reaches of the rivers practically never contained type E. Runoff could deposit type E spores in Green Bay, but this is not considered to be the major factor in the high incidence of the organism. Multiplication in the bay itself is indicated.
Rabbit Ileal Loop Response to Strains of
Clostridium perfringens
Authors: Duncan Charles L. , Sugiyama H. , Strong Dorothy H.
Published: January 2020

The ligated loop of the rabbit intestine was investigated as a possible experimental model for the study of
Clostridium perfringens
food poisoning. The method of preparation of the challenge inoculum was important in determining whether a given strain would provoke a response. When cultures were grown for 4 hr at 37 C in Skim Milk (Difco), 14 of 29 type A strains isolated from food-poisoning outbreaks consistently produced exudation of fluid and consequent dilation of the ileal segments. In contrast, 15 of the 18 strains derived from other sources failed to elicit a response. By use of different inoculum preparations, nearly all strains could be made to give at least an occasional positive loop reaction. Diarrhea was not obtained in rabbits by intraluminal injection into the normal ileum or by per os administration of the cultures. Lecithinase, purified and in concentrated culture supernatant fractions, failed to produce a response in the isolated ileal loops.
In Vitro Activity of Carbenicillin Against Gram-negative Bacilli
Authors: Bodey Gerald P. , Terrell Lois M.
Published: January 2020

The activity of a new semisynthetic penicillin, carbenicillin, was determined against 241 strains of gram-negative bacilli with the tube-dilution technique. Of 143 strains of
Pseudomonas
sp., 99 had a minimal inhibitory concentration of 200 to 300 μg/ml. The majority of strains of
Escherichia coli
and
Proteus
spp. were sensitive to this antibiotic, with minimal inhibitory concentrations of 25 μg/ml or less. Strains of
Klebsiella
sp. were quite resistant to carbenicillin. The size of inoculum had no significant effect on the minimal inhibitory concentration for
Pseudomonas
sp.
Selective Increase in Hydrogen Peroxide Resistance of a Coagulase-positive Staphylococcus
Authors: Amin V. M. , Olson N. F.
Published: January 2020

Staphylococcus
culture 105B was serially treated with 0.05% hydrogen peroxide at 54.4 C or without hydrogen peroxide at this temperature to determine changes in resistance to these conditions and in catalase activity of the surviving populations. Resistance of the final surviving populations to H
2
O
2
treatment and to heat treatment without H
2
O
2
was 5.6 and 4.5 times greater, respectively, than the parent culture. Catalase activities of the cell-free extracts of survivors of the H
2
O
2
treatments and of the heat treatments were 33.56 and 2.69 times greater, respectively, than the control. The untreated control cultures grew in Peptonized Milk (Difco), but addition of sodium pyruvate to the medium was necessary to support growth of survivors.
Cell Division During Inhibition of Deoxyribonucleic Acid Synthesis in
Escherichia coli
Authors: Helmstetter Charles E. , Pierucci Olga
Published: January 2020

When cultures of
Escherichia coli
B/r growing at various rates were exposed to ultraviolet light, mitomycin C, or nalidixic acid, deoxyribonucleic acid (DNA) synthesis stopped but cell division continued for at least 20 min. The chromosome configurations in the cells which divided were estimated by determining the rate of DNA synthesis during the division cycle. The cultures were pulse-labeled with
14
C-thymidine, and the amount of label incorporated into cells of different ages was found by measuring the radioactivity in cells born subsequent to the labeling period. The cells which divided in the absence of DNA synthesis were those which had completed a round of chromosome replication prior to the treatments. It was concluded that completion of a round of replication is a necessary and sufficient condition of DNA synthesis for cell division.
Origin and Sequence of Chromosome Replication in
Escherichia coli
B/r
Authors: Helmstetter Charles E.
Published: January 2020

The initial rates of induced synthesis of tryptophanase, β-galactosidase, and
d
-serine deaminase were measured in relation to the chromosome replication cycle of
Escherichia coli
B/r. Exponentially growing cultures were exposed briefly to
14
C-thymidine or the appropriate inducers (or both), and the amount of label or enzyme (or both) in cells of different ages was found by measuring these quantities in their progeny. The rates of induced synthesis of the three enzymes increased abruptly at about 4, 20, and 34 min, respectively, after the start of a round of replication lasting 40 min. By matching this sequence to the
ind, lac
, and
Dsd
loci on the genetic map of
E. coli
K-12, it was estimated that replication began at about 8 o'clock (60 min) and proceeded clockwise. In rapidly growing cells, the sequence during the division cycle was consistent with the concept that rounds of replication overlapped.
Fatty Acid Replacements in a Fatty Acid Auxotroph of
Escherichia coli
Authors: Silbert David F. , Ruch Frank , Vagelos P. Roy
Published: January 2020

Unsaturated fatty acids having structural features which are different from those of the monoenoic acids normally synthesized by
Escherichia coli
can serve as growth factors for an auxotroph requiring unsaturated fatty acids. These analogues were incorporated into the phospholipids, as shown by gas-liquid and thin-layer chromatographic analysis of the phospholipid fatty acid composition. Some of these fatty acids were
cis
Δ
5
- and
cis
-Δ
9
-tetradecenoic,
cis
-Δ
11
-eicosenoic,
cis,cis
-Δ
11,14
-eicosadienoic,
cis,cis,cis
-Δ
11,14,17
-eicosatrienoic,
trans
-Δ
9
- and
trans
-Δ
11
-octadecenoic acids. Although partial degradation of some of these analogues to shorter even-chain homologues occurred, chain elongation of the exogenous fatty acids was not detected.
Trans
-olefinic acids were utilized without stereochemical or positional isomerization. These studies provide a basis for exploring the properties of the fatty acids and phospholipids required for the formation, structure, and function of membranes.
Metabolism of Carbohydrates by
Pasteurella pseudotuberculosis
Authors: Brubaker R. R.
Published: January 2020

Cell-free extracts of
Pasteurella pseudotuberculosis
and
P. pestis
catalyzed a rapid and reversible exchange of electrons between pyridine nucleotides. Although the extent of this exchange approximated that promoted by the soluble nicotinamide adenine dinucleotide (phosphate) transhydrogenase of
Pseudomonas fluorescens
, the reaction in the pasteurellae was associated with a particulate fraction and was not influenced by adenosine-2′-monophosphate. The ability of
P. pseudotuberculosis
to utilize this system for the maintenance of a large pool of nicotinamide adenine dinucleotide phosphate could not be correlated with significant participation of the Entner-Doudoroff path or catabolic use of the hexose-monophosphate path during metabolism of glucose. As judged by the distribution of radioactivity in metabolic pyruvate, glucose and gluconate were fermented via the Embden-Meyerhof and Entner-Doudoroff paths, respectively. With the exception of hexosediphosphatase, all enzymes of the three paths were detected, although little or no gluconokinase or phosphogluconate dehydrase was present unless the organisms were cultivated with gluconate. The significance of these findings is discussed with respect to the regulation of carbohydrate metabolism in the pasteurellae, related enteric bacteria, and
P. fluorescens
.
The 5′-Nucleotidases and Cyclic Phosphodiesterases (3′-Nucleotidases) of the
Enterobacteriaceae
Authors: Neu Harold C.
Published: January 2020

All members of the
Enterobacteriaceae
possess distinct 5′-nucleotidases and cyclic phosphodiesterases (3′-nucleotidases) that can be differentiated from the acid and alkaline phosphatases and the acid sugar hydrolases. The nucleotidases and cyclic phosphodiesterases of the various
Enterobacteriaceae
are remarkably similar in properties. All of the 5′-nucleotidases hydrolyze 5′-nucleotides, adenosine triphosphate, and uridine diphosphoglucose. Their
p
H optimum is from 5.7 to 6.1. The cyclic phosphodiesterases hydrolyze 3′-nucleotides, cyclic phosphonucleotides, bis-(
p
-nitrophenyl)phosphate, and
p
-nitrophenylphosphate. Their
p
H optimum is from 7.2 to 7.8. For both enzymes, cobalt showed optimal metal stimulation. An intracellular protein inhibitor for the 5′-nucleotidase is present in all of the
Enterobacteriaceae
. No inhibitor of cyclic phosphodiesterase activity exists, although hydrolysis of both cyclic phosphonucleotides and 3′-nucleotides is inhibited by ribonucleic acid. Neither of the enzymes is subject to control by phosphate level or by catabolite repression. Of the other bacteria studied, only
Haemophilus
and
Bacillus subtilis
contained significant 3′- or 5′-nucleotidase activity.
Homogeneity and Molecular Weight of Toxin of
Clostridium botulinum
Type B
Authors: Boroff Daniel A. , Dasgupta B. R. , Fleck U. S.
Published: January 2020

Gerwing et al. described the isolation and purification from culture filtrates of the toxin of
Clostridium botulinum
type B and characterized it as a homogeneous protein of less than 10,000 molecular weight. Analysis by various methods of samples of this toxin obtained from Gerwing et al., and preparations produced by their methods in our laboratories, furnished convincing evidence that neither her preparation nor ours was homogeneous. The molecular weight of the toxic component isolated from either of the preparations was 100,000 or greater and resembled, in a number of respects, the α component isolated by us from the crystalline toxin of
C. botulinum
type A.
Formation of Dulcitol in Aerobic Dissimilation of
d
-Galactose by Yeasts
Authors: Onishi H. , Suzuki T.
Published: January 2020

During the study of aerobic dissimilation of galactose by yeasts, polyhydric products were isolated in crystalline form from the fermented broths and identified. Yeast species may be divided into two groups on basis of sugar alcohol production: type I yeasts form the same end products from galactose as from glucose; type II yeasts produce dulcitol from galactose with or without other sugar alcohols but they produce no dulcitol from glucose. Isolation of dulcitol from microorganism has not been previously described.
Microcalorimetric Study of Glucose Permeation in Microbial Cells
Authors: Belaich Jean-Pierre , Senez Jacques C. , Murgier Maryse
Published: January 2020

A microcalorimetric method for measuring the influence of extracellular glucose concentration on the rate of catabolism is described. This method has been applied to anaerobically growing cultures of
Zymomonas mobilis
and of a respiratory-deficient (“petite”) mutant of
Saccharomyces cerevisiae
(strain YFa). The Michaelian kinetics recorded with both organisms were apparently related to glucose transport. With
Z. mobilis
, it was found that, in the range of glucose concentrations at which this organism was growing exponentially, cell activity was limited by the maximal rate of the catabolic enzymes; at lower concentrations, glucose transport was the rate controlling step. The metabolic activity of yeast always depended on external glucose concentration; when this was lowered under a threshold, a change of kinetics took place. The microcalorimetric method described seems to be widely applicable to kinetic studies of the permeation of metabolizable substrates in microorganisms.
Occurrence of Poly-β-Hydroxybutyrate in the
Azotobacteriaceae
Authors: Stockdale H. , Ribbons D. W. , Dawes E. A.
Published: January 2020

Poly-β-hydroxybutyrate (PHB) from various representative strains of the genera
Azotobacter, Beijerinckia
, and
Derxia
was isolated and characterized. During growth in shake culture, with glucose as a carbon and energy source, and molecular nitrogen as a nitrogen source, increase in dry weight appeared linear, and PHB formed a constant percentage of the dry weight. In a medium containing 1% (w/v) glucose, PHB declined with the onset of the stationary phase of growth; with 2% (w/v) glucose, an increase in PHB content during stationary phase was noted in the case of some strains, before a subsequent decline. The decrease in PHB as a percentage of dry cellular weight (not of total amount present in the culture) during growth of some strains with 2% as opposed to 1% (w/v) glucose may be ascribed to a greater production of capsular polysaccharide. PHB content could not be used as a taxonomic criterion. Strain differences were as great as or greater than species differences. The only strain of
Beijerinckia fluminensis
obtained contained PHB, but it could not be grown on the nitrogen-free medium used. Two species of the genus
Azotomonas
, reported to be aerobic, nonsymbiotic nitrogen-fixers, did not grow on the nitrogen-free medium used and did not produce PHB during growth with a combined nitrogen source.
Properties and Characterization of the Host Bacterium of Bacteriophage PM2
Authors: Espejo Romilio T. , Canelo Eliana S.
Published: January 2020

A marine bacterium, which acts as host for bacteriophage PM2 isolated from the same environment, has been characterized as a
Pseudomonas
species. This
Pseudomonas
cannot be assigned to any of the subgeneric categories or “groups” described by Stanier, Palleroni, and Doudoroff. The psychrophilic and halophilic nature of the organism and its requirement for NaCl suggest an indigenous marine origin.
Identification ofZoogloeaspecies and the Relationship to Zoogloeal Matrix and Floc Formation
Authors: Friedman Barry A. , Dugan Patrick R.
Published: January 2020

Three floc-forming, gram-negative, polarly flagellated rods were isolated and characterized. Our isolates were compared to four similar floc-forming organisms previously isolated in another laboratory and classified as two species ofZoogloea, one ofPseudomonas, and as one unidentified gram-negative rod. Possession of zoogloeal matrix or flocculent growth habit was examined in relation to growth and biochemical patterns of the bacteria. A possible relationship ofZoogloeato other gelatinous matrix-producing bacteria is also discussed.