bluuebunny/crossref_metadata_2025 huggingface dataset:
Pigmentation and Acriflavine Resistance in
Serratia marcescens
Authors: Woods D. R. , Mosmann T. R. , Hanson Sally , Hendry D. A.
Published: January 2020

Stable, orange, acriflavine-resistant variants were selected by treatment of a wild-type, red, acriflavine-sensitive strain of
Serratia marcescens
with acriflavine. Visible, ultraviolet, infrared, and nuclear magnetic resonance spectra of purified pigment from the red strain were identical to those of the pigment from the orange strain, and the orange mutant was not due to a mutation affecting the structure of the pigment, prodigiosin. The color of the red strain was not affected by variations in
p
H between 5.0 and 8.0, whereas the color of the orange mutant changed from pink to orange over the same
p
H range. This variation was mimicked by the
p
H-induced variation in color of prodigiosin purified from either the red, wild-type or the orange, mutant strains. Density-gradient centrifugation of cell fragments after ultrasonic disintegration resulted in characteristic pigmented bands. Biochemical characterization of these pigmented bands showed that they contained pigment and a protein component, but no lipids, polysaccharides, sugars, glucosamine, or phosphates were detected. Further fractionation of these pigmented bands by zone electrophoresis on a sucrose density gradient indicated that some pigment in
S. marcescens
was specifically attached to protein components.
Scanning Electron Microscopy of Intact
Trichoderma
Colonies
Authors: Galun Esra
Published: January 2020

Scanning electron microscopy revealed a clear distinction between hyphal types and enabled early detection of hyphal initiation. Stages in the photoinduced differentiation in
Trichoderma
leading to conidiation could thus be studied.
Purification and Properties of Adenylyl Sulfate Reductase from the Phototrophic Sulfur Bacterium,Thiocapsa roseopersicina
Authors: Truper Hans G. , Rogers Lynne A.
Published: January 2020

Adenylyl sulfate reductase was purified fromThiocapsa roseopersicina60- to 80- fold, and the properties were studied. The molecular weight is 180,000. The enzyme contains, per molecule; one flavine group, two heme groups of cytochromeccharacter, four atoms of nonheme iron, and six labile sulfide groups. Cytochromecand ferricyanide serve as electron acceptors. With ferricyanide as the electron acceptor, thepH optimum of the enzyme is at 8.0; with cytochromec, thepH optimum is at 9.0. Of the nucleotides studied, adenosine 5′-monophosphate is most effective. The influence of substrate concentrations on the activity of the enzyme was studied, and theKmvalues for sulfite, adenosine 5′-monophosphate, ferricyanide, and cytochromecwere determined. The properties of the enzyme are compared with those of adenylyl sulfate reductases purified from sulfate-reducing bacteria and thiobacilli.
Regulation of Two Aspartokinases in
Bacillus subtilis
Authors: Hampton Michael L. , McCormick Neil G. , Behforouz Nancy C. , Freese Ernst
Published: January 2020

When grown on minimal glucose medium, transformable
Bacillus subtilis
strains contained two distinct aspartokinases (ATP:
l
-aspartate 4-phosphotransferase, EC 2.7.2.4). One of these enzymes was inhibited by
l
-lysine (Lys), whereas the other was insensitive to inhibition but was activated by
l
-leucine. None of the other amino acids tested had any effect, and the addition of
l
-threonine did not enhance the inhibition by Lys, in contrast to the concerted inhibition observed for other bacilli. At the end of exponential growth, the Lys-sensitive aspartokinase activity decreased, whereas the Lys-insensitive activity remained relatively constant throughout the stationary phase. The two activities were separated by (NH
4
)
2
SO
4
fractionation and Sephadex G-200 chromatography. Growth in the presence of Lys reduced the specific activity of aspartokinase by about 50% and eliminated the inhibition by Lys. In extracts of these cells, only Lys-insensitive activity was found upon (NH
4
)
2
SO
4
fractionation and Sephadex G-200 chromatography. Lys apparently repressed the synthesis of the Lys-sensitive enzyme.
Effects of Ethidium Bromide on Growth and on Loss of the Penicillinase Plasmid of
Staphylococcus aureus
Authors: Rubin Sally J. , Rosenblum E. D.
Published: January 2020

Ethidium bromide (EB) was more efficient than ethyl violet or rifampin as a curing agent for the penicillinase plasmids of
Staphylococcus aureus
strains. The effects of EB on growth and on the loss of the penicillinase plasmid of PS 81 were studied in detail. The growth rates of PS 81 and an EB-cured derivative were identical in broth, but the cured derivative had a shorter lag in the presence of added 6 × 10
−6
m
EB. The shortened lag was due to prior exposure to EB as the cured derivative and an EB-treated but uncured strain of PS 81 gave identical growth lag and growth rates in the presence of EB. The curing of PS 81 by EB occurs in three phases. After a 4 to 5 hr lag, there is a 100-fold increase in the number of penicillinase-negative cells, and the proportion of cured cells continues to rise until 10 to 12 hr. Thereafter, the population becomes refractory to further curing, and the proportion of penicillinase-negative cells remains constant at about 20% of the total. Penicillinase-positive survivors of EB treatment showed increased EB resistance and were cured at lower rates upon subsequent EB treatment. Isolated colonies of the parental strain PS 81 were heterogeneous in their EB sensitivity. Thus, EB does not competitively favor spontaneously cured penicillinase-negative cells but appears to act in a manner analogous to acridine orange on the plasmids of enteric bacteria.
Regulation of the Mandelate Pathway in
Pseudomonas aeruginosa
Authors: Rosenberg S. L.
Published: January 2020

The pathway of mandelate metabolism in
Pseudomonas aeruginosa
is composed of the following steps:
l
(+)-mandelate → benzoylformate → benzaldehyde → benzoate. These three steps are unique to mandelate oxidation; the benzoate formed is further metabolized via the β-ketoadipate pathway. The first enzyme,
l
(+)-mandelate dehydrogenase, is induced by its substrate. The second and third enzymes, benzoylformate decarboxylase and benzaldehyde dehydrogenase, are both induced by benzoylformate. The same benzaldehyde dehydrogenase, or one very similar to it, is also induced by β-ketoadipate, an intermediate in the subsequent metabolism of benzoate. This dehydrogenase may also be induced by adipate or a metabolite of adipate. These conclusions have been drawn from the physiological and genetic properties of wild-type
P. aeruginosa
strains and from the study of mutants lacking the second and third enzyme activities.
Bacterial Cell Division Regulation: Physiological Effects of Crystal Violet on
Escherichia coli lon
+
and
lon
−
Strains
Authors: Walker James R. , Shafiq Nawal A. , Allen Robert G.
Published: January 2020

The
Escherichia coli lon
−
mutants apparently are defective in the ability to recommence cell division after temporary periods of deoxyribonucleic acid (DNA) synthesis inhibition. They are also more susceptible to cell division inhibition by the basic dye, crystal violet (CV), than are
lon
+
strains. In enriched broth, the
lon
+
strain continued to grow and divide in the presence of CV, but
lon
−
cell division was inhibited and filamentous growth resulted. In a supplemented minimal medium containing CV,
lon
−
cell division was only temporarily inhibited. There was no detectable specific effect on DNA synthesis, although CV slowed the rate of mass increase in both media. Trichloroacetic acid-insoluble lipid synthesis was preferentially inhibited in both
lon
+
and
lon
−
strains. In CV-containing enriched broth, diaminopimelic acid incorporation into trichloroacetic acid-insoluble compounds occurred at a rate greater than the rate of mass increase in both
lon
+
and
lon
−
strains. In a CV-containing supplemented minimal medium, diaminopimelic acid was incorporated to a greater extent by
lon
−
cells than by
lon
+
cells.
Polysaccharides of Type 6Klebsiella
Authors: Gormus B. J. , Wheat R. W.
Published: January 2020

Water-extractable type 6Klebsiellaantigens were separated into a type 6-specific acidic polysaccharide and a neutral polysaccharide. The neutral polymer was devoid of type 6 activity although it was serologically active. The type 6-specific polymer contained fucose, glucose, and mannose, and pyruvic, galacturonic, and possibly glucuronic acids. The neutral polymer contained glucose, galactose, and mannose.
Tumor Induction by
Agrobacterium tumefaciens
: Specific Transfer of Bacterial Deoxyribonucleic Acid to Plant Tissue
Authors: Yajko David M. , Hegeman George D.
Published: January 2020

When
Agrobacterium tumefaciens
cells grown in the presence of tritiated thymidine to label specifically the bacterial deoxyribonucleic acid (DNA) are incubated with carrot root tissue for short periods of time, an appreciable fraction of the label becomes firmly associated with the root tissue. Such association is not observed in identical experiments when
A. tumefaciens
cell ribonucleic acid or protein are labeled. The extent of the retention of thymidine-derived label from bacterial cells by the root tissue in experiments with
A. radiobacter
and poorly tumorigenic strains of
A. tumefaciens
is significantly less than that afforded by tumorigenic strains of
A. tumefaciens
but greater than the level afforded by
Escherichia coli
. Transfer of DNA-specific label from
A. tumefaciens
to carrot root discs is not enhanced by treatments designed to provoke lysis of the bacterial cells, nor is it decreased by addition of deoxyribonuclease or excess unlabeled thymidine to the incubation medium. Bacterial cell-to-plant cell contact is necessary for transfer. Unlabeled
A. radiobacter
cells decrease in a competitive manner transfer of label when mixed with labeled
A. tumefaciens
cells. These findings suggest that transfer of DNA from
A. tumefaciens
to plant tissue after binding of the bacterial cells to specific plant tissue site(s) is a necessary feature of the mechanism by which
A. tumefaciens
provokes tumors in plants and provides an experimental technique of potentially great value in study of the early steps in the process of tumor induction by
A. tumefaciens
.
Incorporation of Radioactive Macromolecular Precursors into Intact Cells and Osmotically Stabilized “Protoplasts” of
Streptococcus faecalis
Authors: Roth George S. , Daneo-Moore Lolita
Published: January 2020

Growing “protoplasts” of
Streptococcus faecalis
were shown to incorporate newly administered radioactive precursors in the same manner as growing intact streptococci. No observable differences could be found between the size of the leucine precursor pools of the two cultures. The extent of turnover of protein and ribonucleic acid in both “protoplast” and streptococcal cultures appeared to be identical. Finally, the absolute rate of macromolecular biosynthesis was found to be equivalent whether determined on the basis of “new” or “old” label incorporation.
New Type of R Factors Incapable of Inactivating Chloramphenicol
Authors: Nagai Yutaka , Mitsuhashi Susumu
Published: January 2020

Four R factors conferring chloramphenicol (CM) resistance were isolated from
Escherichia coli
strains of clinical origin. Strains carrying the factors were found to be incapable of inactivating the drug in the presence of acetyl coenzyme A.
E. coli
W3630 carrying R
70
, one of these factors, became sensitive to CM after treatment with glycine, indicating that the spheroplasts of W3630 R
70
+
were sensitive to the drug and suggesting that the cell membrane is important for CM resistance. The observation that cell-free protein synthesis in W3630 R
70
+
was inhibited by CM is also compatible with a decrease in permeability. CM resistance in W3630 R
70
+
appeared to be inducible, because (i) preincubation with subinhibitory concentrations of CM prevented the prolonged lag noted for growth in the presence of 25 μg of CM per ml, and (ii) the preincubation effect was lost after overnight growth in CM-free medium. By contrast,
E. coli
W3630
cml
+
, in which the resistance determinant is integrated into the chromosome, was capable of rapid inactivation of CM.
E. coli
W3630
cml
+
R
70
+
, which contains the proposed permeability determinant (episomal) as well as levels of the inactivating enzyme (chromosomal) that are comparable with W3630
cml
+
, was capable of brief inactivation of CM when inoculated into drug-containing medium. The absence of continued inactivation on more prolonged incubation favors the hypothesis that the R
70
factor inhibited further penetration of CM and that this property possesses the characteristics of induction.
Induction and Regulation of a Nicotinamide Adenine Dinucleotide-Specific 6-Phosphogluconate Dehydrogenase in
Streptococcus faecalis
Authors: Brown Albert T. , Wittenberger Charles L.
Published: January 2020

Streptococcus faecalis
grown with glucose as the primary energy source contains a single, nicotinamide adenine dinucleotide phosphate (NADP)-specific 6-phosphogluconate dehydrogenase. Extracts of gluconate-adapted cells, however, exhibited 6-phosphogluconate dehydrogenase activity with either NADP or nicotinamide adenine dinucleotide (NAD). This was shown to be due to the presence of separate enzymes in gluconate-adapted cells. Although both enzymes catalyzed the oxidative decarboxylation of 6-phosphogluconate, they differed from one another with respect to their coenzyme specificity, molecular weight,
p
H optimum,

K
m

values for substrate and coenzyme, and electrophoretic mobility in starch gels. The two enzymes also differed in their response to certain effector ligands. The NADP-linked enzyme was specifically inhibited by fructose-1,6-diphosphate, but was insensitive to adenosine triphosphate (ATP) and certain other nucleotides. The NAD-specific enzyme, in contrast, was insensitive to fructose-1,6-diphosphate, but was inhibited by ATP. The available data suggest that the NAD enzyme is involved primarily in the catabolism of gluconate, whereas the NADP enzyme appears to function in the production of reducing equivalents (NADPH) for use in various reductive biosynthetic reactions.
Loss of the Penicillinase Plasmid After Treatment of
Staphylococcus aureus
with Sodium Dodecyl Sulfate
Authors: Sonstein Stephen A. , Baldwin J. N.
Published: January 2020

Two strains of
Staphylococcus aureus
(PC1 and 196E), when grown in medium containing 0.002% sodium dodecyl sulfate (SDS), showed from 96.1 to 100% loss of the ability to produce penicillinase. Resistance to cadmium and zinc was lost concomitantly with the ability to produce penicillinase. A comparison of the rate of curing by SDS with the curing effects exerted by elevated temperature and ethidium bromide suggested that SDS is a more effective plasmid curing agent for susceptible strains of
S. aureus
than methods in use at present.
Genetic and Physiological Control of Serine and Glycine Biosynthesis in
Saccharomyces
Authors: Ulane Rodney , Ogur Maurice
Published: January 2020

Two of the three known metabolic pathways to serine and glycine have been shown to be present in prototrophic yeast strains, i.e., the phosphorylated pathway from glycolytic intermediates and the glyoxylate pathway from tricarboxylic acid cycle intermediates. Two serine-glycine auxotrophs (
ser1
and
ser2
) were found to be blocked in the phosphoglycerate pathway. The
ser1
gene controls
l
-glutamate:phosphohydroxypyruvate transaminase biosynthesis, and the
ser2
gene controls phosphoserine phosphatase biosynthesis. The
other
pathway to glycine, from isocitrate, is repressed by growth in glucose media, specifically, at isocitrate lyase and at the alanine:glyoxylate transaminase. This pathway is derepressed by growth to stationary phase in glucose media yielding high activity of these enzymes. The phosphorylated pathway appears to be the principal biosynthetic pathway to serine and glycine during growth on sugar media. Strains which are serine-glycine dependent in glucose media became capable of serine-glycine independent growth on acetate media. These results describe a method of physiological control of a secondary metabolic pathway allowing a single lesion in the principal biosynthetic pathway to produce auxotrophy. This may be termed conditional auxotrophy.
Purification and Characterization of Phosphoenolpyruvate Carboxylase from
Plasmodium berghei
Authors: McDaniel Huey G. , Siu Patrick M. L.
Published: January 2020

Phosphoenolpyruvate (PEP) carboxylase was purified over 400-fold from
Plasmodium berghei
. The purified enzyme was stable in 0.4
m
potassium phosphate buffer (
p
H 7.4) containing 0.5
m
glucose, 1 m
m
ethylenediaminetetraacetic acid (EDTA), and 1 m
m
MgCl
2
. It had a molecular weight of 280,000 determined by sucrose density gradient centrifugation in this buffer, but it aggregated and was unstable in the presence of different salts or a more dilute solution of potassium phosphate. The
K
m
for PEP was 2.6 m
m
and that for Mg
2+
was 1.3 m
m
. The
K
m
for bicarbonate was 2 m
m
. Citrate, nucleotides, and EDTA inhibited the PEP carboxylase of
P. berghei
by decreasing the concentration of free magnesium ions, but acetyl-coenzyme A, fructose-1,6-diphosphate, and aspartate did not influence its activity. A chloroquine concentration of 1.8 × 10
−4
m
inhibited the enzyme 50%.
Effect of Membrane Lipid Composition on the Allosteric Inhibition by Sodium of the (Ca
2+
)-Adenosine Triphosphatase from
Escherichia coli
Authors: Farias Ricardo N. , Londero Leonor , Trucco Raúl E.
Published: January 2020

The allosteric inhibition by sodium of the (Ca
2+
)-adenosine triphosphatase (EC 3.6.1.3) from
Escherichia coli
was found to be dependent on the lipid composition of the cell membrane.
Studies on the Diversity of Inositol-Containing Yeast Phospholipids: Incorporation of 2-Deoxyglucose into Lipid
Authors: Steiner S. , Lester Robert L.
Published: January 2020

Seven inositol-containing phospholipids in
Saccharomyces cerevisiae
can be resolved by two-dimensional chromatography on silicic acid-impregnated paper. Four of these lipids are stable to mild alkaline methanolysis; one of these has already been characterized as a mannosyl di(inositolphosphoryl) ceramide. Addition of labeled 2-deoxy-
d
-glucose to a growing culture results in label appearing in five lipids, some of which are alkali-stable and have the same

R
F

values as the alkali-stable inositol-containing phospholipids. These lipids are labeled rapidly. The deoxyglucose is incorporated intact, probably in a glycosidic link, since the deoxyglucose is released by mild acid treatment.
Biochemistry and Genetics of Galactose Metabolism in Group H
Streptococcus
Strain Challis
Authors: Luginbuhl Geraldine H. , Gooder Harry
Published: January 2020

Galactose-negative mutants of the group H
Streptococcus
strain Challis were obtained by treatment with nitrosoguanidine. Enzyme assays of extracts of these mutants revealed that 12 of the mutants were lacking one of the enzymes of the Leloir pathway. Thus, the Leloir pathway is the major means of galactose metabolism in strain Challis. In addition, uridyl diphosphate galactose pyrophosphorylase, a permease function, and at least one other function are required for the utilization of galactose. The enzymes of the Leloir pathway are induced by galactose and fucose; no compounds which act as repressors of these enzymes have been found, although the system appears to be sensitive to catabolite repression. Transformation was used to map the mutants. The genes for galactose-1-phosphate uridyl transferase and glucose-4-epimerase appear to be closely linked. Within the transferase gene, six mutations have been mapped. The permease function and the undetermined functions are not linked to the Leloir pathway.
Leakage of Periplasmic Enzymes by Mutants of
Escherichia coli
and
Salmonella typhimurium:
Isolation of “Periplasmic Leaky” Mutants
Authors: Lopes J. , Gottfried S. , Rothfield L.
Published: January 2020

Mutants of
Escherichia coli
and
Salmonella typhimurium
were selected on the basis of their spontaneous leakage of ribonuclease I. The mutants also leaked several other periplasmic enzymes into the medium during active growth but did not leak the intracellular enzymes glucose-6-phosphate dehydrogenase or phosphoglucose isomerase.
Occurrence of Taurine:α-Ketoglutarate Aminotransferase in Bacterial Extracts
Authors: Toyama Seizen , Soda Kenji
Published: January 2020

High activity of taurine:α-ketoglutarate aminotransferase was found exclusively in cell-free extracts of
Achromobacter superficialis
and
A. polymorph
. The former was chosen for characterization of the enzymatic reaction. The enzyme activity was enhanced by addition of β-alanine to the growth medium. The product from α-ketoglutarate was identified as
l
-glutamate. Another product has been isolated, purified, and identified as sulfoacetaldehyde (2-oxoethanesulfonate), a deamination product from taurine, by comparison between the 2,4-dinitrophenylhydrazones of the synthetic and enzymatic products on the basis of studies by paper chromatography, by visible, infrared, and nuclear magnetic resonance spectrophotometries, and by elemental analysis. This enzymatic transamination was found to proceed stoichiometrically and reversibly as follows: NH
2
·CH
2
·CH
2
·SO
3
H + HOOC·CH
2
·CH
2
·CO·COOH ⇌ OHC·CH
2
·SO
3
H + HOOC·CH
2
·CH
2
·CH(NH
2
)·COOH.
Regulation of Secondary Metabolite Biosynthesis: Catabolite Repression of Phenoxazinone Synthase and Actinomycin Formation by Glucose
Authors: Gallo Maria , Katz Edward
Published: January 2020

Synthesis of the secondary metabolite, actinomycin, and the enzyme, phenoxazinone synthase, involved in the biosynthesis of the antibiotic, were shown to be under severe catabolite repression by glucose. Of a variety of hexoses and carbon compounds examined, glucose, and to a lesser extent, mannose, proved to be the most repressive for enzyme synthesis. The repression by glucose was most evident before production of the antibiotic. In a chemically defined medium suitable for actinomycin production, synthesis of phenoxazinone synthase began at the time the glucose (0.1%) supply was depleted. Soon after, antibiotic synthesis was initiated. Galactose, the major carbon source for growth and antibiotic synthesis, was not utilized until the glucose was consumed. Generally, carbon compounds which supported a rapid rate of growth were most effective in producing catabolite repression.
Biosynthesis of Cardiolipin from Phosphatidylglycerol in
Staphylococcus aureus
Authors: Short Steven A. , White David C.
Published: January 2020

Cardiolipin (CL) synthetase from
Staphylococcus aureus
catalyzes the complete conversion of two molecules of phosphatidylglycerol (PG) to one molecule of CL and one molecule of glycerol. The fatty acids and phosphates of the two PG molecules can be quantitatively recovered in the CL. The enzyme is membrane-bound, shows a linear relationship with the product formed between 10 and 125 μg of membrane protein, has a
p
H optimum at 4.4, a temperature optimum between 37 and 45 C, a
K
m
for PG of 2.1 × 10
−4
m
, a
V
max
of 200 nmoles of CL per min per mg of membrane protein, and does not require monovalent or divalent metals for activity. The enzyme has no nucleotide requirement and is not affected by prolonged dialysis, and treatment of the enzyme with charcoal has no effect on its activity. The enzyme has no phosphomonoesterase or phosphodiesterase activity, does not act on CL, is specific for PG, and CL and glycerol are the sole products of its activity. Other lipids do not stimulate or inhibit its activity. The enzyme is inhibited by organic solvents and some detergents. There is sufficient CL synthetase activity to account for CL synthesis during exponential growth. Inhibition of CL hydrolysis during growth results in an increase in CL that is balanced by a loss of PG. The activity of CL synthetase is not affected by cytidine diphosphate diglyceride but is inhibited competitively by the product, CL.
Uninducible Mutants in the
gal i
Locus of
Saccharomyces cerevisiae
Authors: Douglas H. C. , Hawthorne D. C.
Published: January 2020

Uninducible galactose nonfermenter mutants of
Saccharomyces cerevisiae
have been isolated and mapped in the
gal i
locus. They appear to be analogous to the
i
s
mutations found in the regulatory genes of the
Escherichia coli
lactose and galactose systems. The susceptibility to suppression by an ochre suppressor of an
i
allele in an
i
s
i
−
double mutant suggests that the
i
locus in
S. cerevisiae
codes for a protein.
Synthesis of Trachoma Agent Proteins in Emetine-Treated Cells
Authors: Becker Yechiel , Asher Yael
Published: January 2020

Trachoma agent develops in emetine-treated cells in the absence of host cell protein synthesis. The time course of protein synthesis throughout the trachoma developmental cycle and the effect of antibiotics on this process were investigated.
The pi-Histidine Factor of
Salmonella typhimurium:
a Demonstration that pi-Histidine Factor Integrates into the Chromosome
Authors: Levinthal Mark , Yeh Jen
Published: January 2020

The
Salmonella typhimurium
pi-histidine episome was identified by Ames et al. (2) in an unstable partial revertant of a deletion mutation-containing strain,
hisG203. HisG203
lacks the histidine operator, promoter, and part of the first structural gene. In this paper, we study some properties of pi factor and demonstrate a low frequency of pi integration into the chromosome at or near the histidine region.
Production byAeromonasof Common Enterobacterial Antigen and Its Possible Taxonomic Significance
Authors: Whang H. Y. , Heller M. E. , Neter E.
Published: January 2020

In a study of production of the common enterobacterial antigen (CA) by members of theAeromonasgroup, ten strains ofA. shigelloides, nine strains ofA. hydrophila, and nine strains ofA. salmonicidawere used. Passive hemagglutination and hemolysis tests as well as the hemagglutination-inhibition procedure revealed that all strains ofA. shigelloides, in contrast to the strains of the other two species, produce this antigenic determinant. The antigen ofA. shigelloideswas demonstrated even when the supernatant fluids of agar-grown cultures were used in a dilution of 1:1,000, whereas 10-times concentrated supernatant fluids obtained from the other two species were negative. Supernatant liquids of cultures ofA. shigelloidesfailed to induce a significant CA immune response in rabbits; nonetheless, the animals were primed immunologically and responded with prompt production of CA antibodies in significant titers to a booster injection of a subeffective dose of CA obtained fromSalmonella typhimurium. Strains ofA. hydrophilaandA. salmonicidaneither induced CA antibody formation nor primed the animals. It is concluded that of the three species of theAeromonasgroup onlyA. shigelloides, which may produce O antigen cross-reacting withShigella sonneiand which has been isolated from patients with dysentery or gastroenteritis, produces CA. Production of this antigen, therefore, may help to characterize microorganisms belonging or related to the familyEnterobacteriaceae.
Control of the Pathway of γ-Aminobutyrate Breakdown in
Escherichia coli
K-12
Authors: Dover Shabtay , Halpern Yeheskel S.
Published: January 2020

Mutants of
Escherichia coli
K-12 isolated for their ability to utilize γ-aminobutyrate (GABA) as the sole source of nitrogen exhibit a concomitant several-fold increase in the activities of γ-aminobutyrate-α-ketoglutarate transaminase (GSST, EC 2.6.1.19) and succinic semialdehyde dehydrogenase (SSDH, EC 1.2.1.16). The increase in rate of enzymatic activity is not accompanied by any changes in the affinities of the mutant enzymes for their respective substrates. The synthesis of the two enzymes is highly coordinate under a great variety of conditions, in spite of the wide range of activities observed. In cultures grown in minimal media with ammonium salts as the source of nitrogen, both GSST and SSDH are severely repressed by glucose. Substitution of ammonia with GABA, glutamate, or aspartate greatly reduces the effect of glucose on the synthesis of the GABA utilization enzymes. This escape from catabolite repression is specific for GSST and SSDH and does not involve other enzymes sensitive to catabolite repression (e.g., β-galactosidase, EC 3.2.1.23, and aspartase, EC 4.3.1.1).
Chromosomal Localization of the Structural Genes of the Polypeptide Chain Elongation Factors
Authors: Gordon Julian , Baron L. S. , Schweiger Manfred
Published: January 2020

A survey of the polypeptide chain elongation factors in potentially sexually compatible genera was carried out. Factors from
Escherichia coli
and
Proteus mirabilis
were found to be clearly distinguishable by immunochemical and electrophoretic techniques. Mapping of the structural genes of these factors was undertaken by a study of the gene products in genetically defined
E. coli-P. mirabilis
hybrid diploid strains. It was found that the EF G factor mapped within 5 min of the streptomycin resistance locus, but the EF Ts factor did not map in this region.
Effects of Acridine Orange on the Growth of
Escherichia coli
Authors: Southwick Frederick S. , Carr Howard S. , Carden George A. , D'Alisa Rose M. , Rosenkranz Herbert S.
Published: January 2020

Exposure of
Escherichia coli
to critical acridine orange (AO) concentrations did not result in loss of viability. However, the deoxyribonucleic acid (DNA) of cells exposed to such agents was rapidly degraded and repolymerized. On the other hand, a bacterium deficient in DNA repair (
pol A
1
−
, lacking DNA polymerase) was sensitive to the action of AO. The DNA of such cells was also degraded but it was not repaired.
Ribosome Degradation and the Degradation Products in Starved
Escherichia coli
Authors: Maruyama Hiromi B. , Okamura Shoji
Published: January 2020

The properties of the abnormal ribonucleoprotein particles produced by
Escherichia coli
Q-13 starved for glucose were studied. Smaller species of these partially deproteinized particles separable to six distinct sizes contained partially degraded ribonucleic acids. The mode of ribosome degradation under this condition is discussed in terms of differential appearance of these intermediate particles.
Aggregation of Deoxyribonucleic Acid and the Helping Effect in Transformation
Authors: Metzer Esther , Ravin Arnold W.
Published: January 2020

Deoxyribonucleic acid aggregates in the presence of a component of Neopeptone at low ionic strength and thereby loses its ability to bind to competent bacteria. The reversible and concentration-dependent nature of this aggregation is the basis of the helping effect in transformation.
Degree of Participation of Exogenous Thymidine in the Overall Deoxyribonucleic Acid Synthesis in
Escherichia coli
Authors: Rosenbaum-Oliver Daphna , Zamenhof Stephen
Published: January 2020

Utilization of labeled exogenous deoxythymidine (TdR) for deoxyribonucleic acid (DNA) synthesis is widely used as a measure of DNA synthesis itself, on the assumption that the degree of participation (DP) of TdR in the overall synthesis of deoxythymidine monophosphate in DNA is constant under a variety of conditions. It is now found that in
Escherichia coli
DP (ratio of exogenous TdR incorporated into DNA to total TdR content of DNA) depends on many factors. In basal medium, DP is 38% in wild-type strain K-12SH and 48% in strain K-12SH28 mutated in the TdR phosphorylase gene. In thymine-requiring (T
−
) mutants having a functional TdR phosphorylase, DP is less than 100%. Shortening the doubling time of the cells by supplementing basal medium with all amino acids increases DP of K-12SH and K-12SH28 by 25%, and T
−
strains do reach 100%. Slowing cell growth by lowering the temperature to 30 C results in a decrease of DP by 15%. In the logarithmic phase, DP is higher than in the beginning of the stationary phase. It appears that exogenous TdR is more convenient for DNA synthesis during faster cell growth.
Comparison of Deoxyribonucleic Acid Uptake and Marker Integration in Bacilli and Protoplasts of
Bacillus subtilis
Authors: Miller Irving L. , Palmer C. Dwayne , Landman Otto E.
Published: January 2020

trp
+
his
−
donor deoxyribonucleic acid (DNA) was added to highly competent
trp
−
his
+
recipient bacilli and to protoplasts prepared from these bacilli, and the cell-DNA complexes were incubated for 30 min. The complexes were then washed and lysed, and their DNA was analyzed on a
trp
−
his
−
strain for the donor marker
trp
+
, the resident marker
his
+
, and for the recombinant
trp
+
his
+
combination. The extracts of the bacillary complexes contained a normal percentage of donor markers (0.1-0.2%), and the number of
trp
+
his
+
doubles (20% of all
trp
+
transformants) indicated that the donor DNA had become integrated into the resident genomes. The protoplast complexes contained 10 to 1,000 times fewer donor markers and almost no recombinants. This indicated that, in protoplasts, marker uptake was minimal and recombination was absent. Uptake was also measured with
3
H-labeled DNA. On the average, protoplasts took up one-fiftieth as much DNA as bacilli. It was concluded that, probably, protoplasts took up no DNA at all, that there were no DNA affinity sites on the surface of the protoplasts, and that the residual marker and radioactivity uptake was due to imperfections in the experimental system. The data and conclusions differed sharply from earlier ones of Hirokawa and Ikeda despite the fact that the techniques of these authors were followed in repeat experiments.
Demonstration of Two Cryptic Plasmids in
Salmonella pullorum
MS53
Authors: Olsen William L. , Schoenhard D. E.
Published: January 2020

Two cryptic plasmids designated PO-1 and PO-2 that had molecular weights of 1.5 × 10
6
and 45 × 10
6
daltons, respectively, were isolated from
Salmonella pullorum
MS53. A 150 to 1 ratio of PO-1 to PO-2 plasmids was estimated to occur.
Gene Transfer in
Pasteurella pestis
Harboring the F′
Cm
Plasmid of
Escherichia coli
Authors: Lawton William D. , Stull Harold B.
Published: January 2020

A strain of
Pasteurella pestis
, harboring the F′
Cm
plasmid from
Escherichia coli
, was able to donate its chromosome to auxotrophic recipient strains of
P. pestis
. The frequency of gene transfer in
P. pestis
was approximately 10
−6
per donor cell, 100 times less efficient than gene transfer in
Pasteurella pseudotuberculosis
, but efficient enough to determine entry times for the markers histidine, threonine, and tryptophan and to show linkage to the markers arginine and pigmentation. An attempt to extend the conjugation system to different serotypes of
P. pseudotuberculosis
and to
Yersinia enterocolitica
did not succeed.
Conditional Mutants of
Staphylococcus aureus
Defective in Cell Wall Precursor Synthesis
Authors: Good C. M. , Tipper D. J.
Published: January 2020

Temperature-sensitive (ts) mutants of
Staphylococcus aureus
with defective cell wall biosynthesis have been differentiated from other ts mutants by their ability to grow at the restrictive temperature (43 C) in the presence of 1
m
NaCl. Under all conditions they possess normal colonial and cellular morphology at the level of resolution of the light microscope and are, therefore, not protoplasts. However, differences between mutant and wild-type cells can be seen by scanning electron microscopy. Many of the mutants contained concentrations of nucleotide precursors of peptidoglycan synthesis in excess of those present in wild-type cells, at both 30 and 43 C. The types of peptidoglycan precursors accumulated by six of the mutants have been determined, and specific enzymatic defects in three of these have been identified.
Use of Neomycin in the Isolation of Mutants Blocked in Energy Conservation in
Escherichia coli
Authors: Kanner Baruch I. , Gutnick David L.
Published: January 2020

A neomycin-resistant mutant of
Escherichia coli
K-12 unable to grow on Krebs cycle intermediates has been isolated. The mutant retained its respiratory capacity, but lacked membrane Mg
2+
-Ca
2+
-stimulated adenosine triphosphatase activity (EC 3.6.1.3).
Kinetics of Deoxyribonucleic Acid Destruction and Synthesis During Growth ofBdellovibrio bacteriovorusStrain 109D onPseudomonas putidaandEscherichia coli
Authors: Matin Abdul , Rittenberg Sydney C.
Published: January 2020

During the growth ofBdellovibrio bacteriovorusonPseudomonas putidaorEscherichia coliin either 10−3mtris(hydroxymethyl)aminomethane or in dilute nutrient broth, the host deoxyribonucleic acid (DNA) was rapidly degraded, and by 30 to 60 min after the initiation of the bdellovibrio development cycle essentially all host DNA became nonbandable in CsCl gradients. At this stage the host DNA degradation products were nondiffusable, and there was no appreciable pool of low-molecular-weight (cold acid soluble) DNA fragments in the cells or in the suspending medium. Bdellovibrio DNA synthesis occurred only after degradation of host DNA to a nonbandable form was complete. The synthesis occurred in a continuous fashion withP. putidaas the host and in two separate periods withE. colias host. By usingE. colicontaining a3H-thymidine label, it was shown that 73%, on the average, of the thymine residues of host DNA were incorporated into bdellovibrio DNA whenE. coliwas the only source of nutrient. In the presence of dilute nutrient broth, the host cells still served as the major source of precursors for bdellovibrio DNA synthesis, with only 20% of the precursors arising from the exogenous nutrients. The data indicate an efficient and controlled utilization of host DNA by the bdellovibrio. The host DNA is apparently degraded early in the developmental cycle to oligonucleotides of intermediate molecular weight from which the biosynthetic monomers are generated only as they become needed for bdellovibrio DNA synthesis.
Identification of Two
Saccharomyces cerevisiae
Cell Wall Mannan Chemotypes
Authors: Cawley T. N. , Ballou Clinton E.
Published: January 2020

We have obtained evidence for two structurally and antigenically different
Saccharomyces cerevisiae
cell wall mannans. One, which occurs widely and is found in
S. cerevisiae
strain 238C, is already known to be a neutral mannan which yields mannose, mannobiose, mannotriose, and mannotetraose on acetolysis of the (1 → 6)-linked backbone. The other, which was found in
S. cerevisiae
brewer's strains, is a phosphomannan with a structure very similar to that of
Kloeckera brevis
mannan.
S. cerevisiae
(brewer's yeast strain) was agglutinated by antiserum prepared against
Kloeckera brevis
cells. The mannan, isolated from a proteolytic digest of the cell wall of the former, did not react with
S. cerevisiae
238C antiserum, whereas it cross-reacted strongly with
K. brevis
antiserum. Controlled acetolysis cleaved the (1 → 6)-linkages in the polysaccharide backbone and released mannose, mannobiose, mannotriose, and mannotriose phosphate. Mild acid treatment of the phosphomannan hydrolyzed the phosphodiester linkage, yielding phosphomonoester mannan and mannose. The resulting phosphomonoester mannan reacted with antiserum prepared against
K. brevis
possessing monoester phosphate groups on the cell surface. α-
d
-Mannose-1-phosphate completely inhibited the precipitin reaction between brewer's yeast mannan and the homologous antiserum. Flocculent and nonflocculent strains of this yeast were shown to have similar structural and immunological properties.
Isoleucine Auxotrophy Due to Feedback Hypersensitivity of Biosynthetic Threonine Deaminase
Authors: Springer W. , Grimminger H. , Lingens F.
Published: January 2020

Isoleucine-deficient mutants of
Salmonella typhimurium
were isolated. Three groups of mutants can be discerned by their nutritional requirements and enzyme patterns. (i) Mutants which grow with isoleucine alone are devoid of biosynthetic threonine deaminase (TD). (ii) Mutants growing with isoleucine and valine are devoid of transaminase B. (iii) Mutants growing with either isoleucine or threonine have normal levels of TD. However, the sensitivity of this enzyme to feedback inhibition by isoleucine is greatly enhanced. The inhibitory effect of isoleucine can be counterbalanced by high concentrations of threonine. These results indicate that the production of isoleucine in the mutants is restricted to a low level not sufficient to support the growth of the cells. This hypothesis is confirmed by studies with revertants of an isoleucine-threonine mutant. In nine revertants, wild-type properties of TD have been restored. In four revertants, the hypersensitivity of TD is unchanged, but the strains produce a greatly enhanced quantity of threonine, which is excreted into the culture medium. It follows, that hypersensitivity of TD to inhibition by isoleucine is the cause of the nutritional requirement of isoleucine-threonine mutants.
Comparative Electrophoretic and Amino Acid Analyses of Isolated Membranes from
Streptococcus pyogenes
and Stabilized L-Form
Authors: Panos C. , Fagan G. , Zarkadas C. G.
Published: January 2020

Major quantitative, but not qualitative, differences in the various species of proteins in purified membranes from
Streptococcus pyogenes
and its stabilized L-form have been demonstrated by acidic and alkaline disc gel electrophoresis with and without urea. The fact that no significant differences in the amino acid content or composition between these two membranes could be demonstrated emphasizes that these results are probably due to changes in the relative amounts of the various species of proteins in this subcellular component. The possibility of these protein changes in the L-form membrane being related to its inability to synthesize a rigid cell wall is discussed. Finally, phage-associated lysin, routinely used for removal of the group A streptococcal cell wall, does not appear to affect the protein profile or amino acid composition of the membrane either metabolically or nonmetabolically.
Cystathionine Synthesis in Yeast: an Alternative Pathway for Homocysteine Biosynthesis
Authors: Savin Michael A. , Flavin Martin
Published: January 2020

Cystathionine synthesis from
O
-acetylhomoserine and cysteine has been demonstrated in yeast extracts for the first time. The activity is less than that of
O
-acetylhomoserine sulfhydrylase, but it is higher than that reported for homoserine
O
-transacetylase and therefore should not be growth limiting. Cystathionine synthase seems to share the regulatory properties of the sulfhydrylase, and both activities are missing from the methionine auxotroph
Saccharomyces cerevisiae
EY9, suggesting that both reactions are catalyzed by the same enzyme. However, cystathionine synthase activity was lost during purification of the sulfhydrylase, suggesting that the two reactions may be catalyzed by separate enzymes. Since previous studies have shown that yeast extracts can catalyze the cleavage of cystathionine to homocysteine, our results show the existence of two complete alternate pathways for homocysteine biosynthesis in yeast. Which of these is the major physiological pathway remains to be determined.
Isolation and Characterization of Mutants of
Escherichia coli
with Cellular Division Selectively Affected by Growth on Fatty Acids
Authors: Samuel D. , Paris S. , Ailhaud G.
Published: January 2020

Isolation and characterization of mutants of
Escherichia coli
that beta-oxidize fatty acids at normal rates, but which divide very slowly when grown on fatty acids, are described. These mutants grow normally on other carbon sources. By growth on oleate, experiments with radioactive precursors showed that the rates of incorporation into ribonucleic acid, protein, and cell wall were comparable to those observed with the parent, whereas the rate of incorporation into phospholipids was slightly decreased. Under these conditions the rate of incorporation of
32
P-orthophosphate into deoxyribonucleic acid was low. On the other hand, by growth on oleate, neither gross mass increase in the different macromolecules nor loss of viability was observed, whereas in the presence of inducer the derepression of the
lac
operon enzymes occurred. Therefore, extensive turnover of the macromolecules is involved when these mutants are grown on fatty acids. Studies of the crypticity and of the binding of 1-anilino-8-naphthalene sulfonate show differences in membrane structure between the mutants and the constitutive parent. Properties of these mutants, which are affected in the process of cellular division, are discussed.
Metabolism of Propane,
n
-Propylamine, and Propionate by Hydrocarbon-Utilizing Bacteria
Authors: Blevins W. T. , Perry J. J.
Published: January 2020

Studies were conducted on the oxidation and assimilation of various three-carbon compounds by a gram-positive rod isolated from soil and designated strain R-22. This organism can utilize propane, propionate, or
n
-propylamine as sole source of carbon and energy. Respiration rates, enzyme assays, and
14
CO
2
incorporation experiments suggest that propane is metabolized via methyl ketone formation; propionate and
n
-propylamine are metabolized via the methylmalonyl-succinate pathway. Isocitrate lyase activity was found in cells grown on acetate and was not present in cells grown on propionate or
n
-propylamine.
14
CO
2
was incorporated into pyruvate when propionate and
n
-propylamine were oxidized in the presence of NaAsO
2
, but insignificant radioactivity was found in pyruvate produced during the oxidation of propane and acetone. The
n
-propylamine dissimilatory mechanism was inducible in strain R-22, and amine dehydrogenase activity was detected in cells grown on
n
-propylamine. Radiorespirometer and
14
CO
2
incorporation studies with several propane-utilizing organisms indicate that the methylmalonyl-succinate pathway is the predominant one for the metabolism of propionate.
Isolation, Identification, and Characterization of a Lipoate-Degrading Pseudomonad and of a Lipoate Catabolite
Authors: Shih Jason C. H. , Wright Lemuel D. , McCormick Donald B.
Published: January 2020

A strain of bacteria that can degrade lipoic acid was isolated from soil. The bacterium, adapted to use 0.4%
dl
-lipoate as the sole organic substrate to supply carbon, sulfur, and energy, was identified morphologically and physiologically as a strain of
Pseudomonas putida
. Degradation of
1,6
-
14
C
-lipoic acid, synthesized from
1,6
-
14
C
-adipic acid, was evidenced by: (i) loss of approximately 50% of the total radioactivity from the medium after bacterial growth; (ii) appearance of
14
C-degradation products upon paper and thin-layer chromatography of the culture medium; and (iii) oxygraphically measured utilization of O
2
by cells in the presence of lipoate or other oxidizable substrates. Analyses of the benzene extract of culture medium by infrared, nuclear magnetic resonance, and mass spectrometry, and by gas-liquid chromatography after desulfuration, have characterized bisnorlipoic acid, or 4,6-dithiohexanoic acid, as the major catabolite present in the medium. β-Oxidation of the side chain is thus proven to be a pathway employed by the pseudomonad to degrade lipoic acid.