bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnesium Starvation of
Aerobacter aerogenes
II. Rates of Nucleic Acid Synthesis and Methods for Their Measurement
Authors: Kennell David , Kotoulas Angeliki
Published: January 2020

The rates of synthesis of
Aerobacter aerogenes
nucleic acids were estimated during incubation of the bacteria in a Mg
++
-free medium. Deoxyribonucleic acid (DNA) synthesized during Mg
++
starvation, or in the preceding exponential growth, remained acid-precipitable for 2.5 hr before breaking down to acid-soluble products during a period of many hours. Rates of DNA synthesis were calculated by correcting the net amounts of DNA per milliliter to values that would have appeared had there been no decay. After the first few hours, this rate was constant, the amount of DNA present at the start of Mg
++
starvation being synthesized every 130 min. Rates of synthesis of total ribonucleic acid (RNA) were established in two ways: (i) by measurements of the incorporation of exogeneous uracil and glucose carbon into RNA, and (ii) by the accumulation of transfer RNA (tRNA), since this component is stable during Mg
++
starvation. After the first few hours, this rate was constant, the amount of RNA present at the start of Mg
++
starvation being synthesized about every 120 min. Fractionation by gradient centrifugation revealed that at all times of starvation the ratio of newly synthesized tRNA-rRNA was the same as it was during exponential growth. Furthermore, newly synthesized ribosomal RNA (rRNA) became a part of polysomal structures. Thus, in the absence of Mg
++
, DNA, tRNA, and rRNA were synthesized in the same relative proportions as during exponential growth, at rates close to one-half the instantaneous rates of synthesis in the bacteria growing exponentially at the start of starvation.
F Pilus as f+Antigen
Authors: Ishibashi Masahide
Published: January 2020

Specific aggregate formation of F pili was observed, by electron microscopy, in a mixture of maleEscherichia coli(or of isolated F pili) and anti-f+serum. Cellular appendages other than F pili never showed such aggregation when mixed with anti-f+serum. The f+agglutinability of male cells, as well as F piliation, was sensitive to mechanical agitation. The f+agglutination was inhibited when appropriate numbers of phage M12, capable of attaching to F pili, were mixed with the male culture before the addition of anti-f+serum. Correlation between f+agglutinability and the extent of F piliation was observed. It was concluded that the F pilus is the structure of the f+antigen and is responsible for f+agglutination.
Fine Structure of
Sarcina maxima
and
Sarcina ventriculi
Authors: Holt Stanley C. , Canale-Parola E.
Published: January 2020

The fine structure of
Sarcina maxima
and
S. ventriculi
was studied by electron and phase-contrast microscopy. The two organisms differ mainly with respect to their cell surface. A thick cellulose layer present on the cell wall of
S. ventriculi
was not observed on the surface of
S. maxima
. Carbon replication indicated that the outer surface of
S. ventriculi
is rough in contour, probably as the result of the fibrillar nature of the accumulated cellulose. The cytoplasm of both sarcinae contains inclusions similar to polysaccharide and polymetaphosphate granules. Mesosomes were observed in cells of
S. maxima
. Packets of
S. ventriculi
generally comprise a larger number of cells and are more irregularly constructed than those of
S. maxima
. Cells in large packets of
S. ventriculi
assume flattened or otherwise irregular shapes, whereas cells of
S. maxima
maintain a more uniform appearance.
Production and Ultrastructure of Lysozyme and Ethylenediaminetetraacetate-Lysozyme Spheroplasts of
Escherichia coli
Authors: Birdsell D. C. , Cota-Robles E. H.
Published: January 2020

Spheroplast production by lysozyme and ethylenediaminetetraacetate (EDTA) was examined as a means of obtaining osmotically sensitive cells for studies of enzyme localization. Physiologically young cells plasmolyzed with 0.5
m
sucrose in 0.01
m
tris(hydroxymethyl)aminomethane (Tris) buffer (
p
H 7, 8, or 9) were quantitatively converted to plasmolyzed osmotically sensitive rods after lysozyme treatment. Although such cells were osmotically sensitive, a 1:1 dilution in Tris buffer was necessary for conversion of rods into spheroplasts. Addition of EDTA resulted in a rapid conversion of the plasmolyzed spheroplasts into spherical structures devoid of a plasmolysis vacuole. These structures, which we call EDTA-lysozyme spheroplasts, contained a number of attached membranes. We believe that this conversion results from a weakening of the outer trilaminar component of the cell wall by EDTA, resulting in the collapse of the plasmolysis vacuole. Dilution of sucrose below 0.15
m
also resulted in the collapse of the plasmolysis vacuole. Both the lysozyme spheroplasts and the EDTA-lysozyme spheroplasts were osmotically sensitive. Thin sections of the EDTA-lysozyme spheroplasts demonstrated that the outer trilaminar component of the cell wall was broken, exposing large areas of the cytoplasmic membrane to the environment.
Group A Streptococcal L Forms I. Persistence Among Inoculated Mice
Authors: Schmitt-Slomska J. , Sacquet E. , Caravano R.
Published: January 2020

L forms induced from two strains of group A
Streptococcus
were inoculated intraperitoneally and intravenously into conventional and germ-free mice. After intravenous injection, streptococcal L forms disappeared very quickly from the blood, whereas, after intraperitoneal injection, it was possible to isolate them as long as 25 days after inoculation. Observations suggest that a certain degree of reversion to a bacterial form may occur spontaneously in animals.
Function of Growth Factors for Rumen Microorganisms I. Nutritional Characteristics of
Selenomonas ruminantium
Authors: Kanegasaki Shiro , Takahashi Hajime
Published: January 2020

Nutritional characteristics of
Selenomonas ruminantium
var.
lactilytica
isolated from a sheep rumen were studied. The organism required for growth the addition of a clarified rumen fluid to a Trypticase-yeast extract medium with either lactate or glucose as an energy source. The requirement for rumen fluid was found to be satisfied by volatile fatty acids in glucose media and by biotin in lactate media. Straight-chain saturated fatty acids with C
3
to C
10
carbon skeleton had been found to be effective. Among them,
n
-valerate was most effective at the lowest concentration. An abnormal morphology was observed with
n
-valerate-deficient glucose media.
n
-Valerate was essential in glucose media, and it was stimulatory in lactate media. Fermentation products from glucose were lactate, propionate, and acetate, and fermentation products from lactate were propionate and acetate. When cells were grown in a glucose medium containing
n
-valerate-
C
14
, the label was present in cell fractions. Almost all of the activity was found in lipid materials.
Toxic Properties of the Cell Wall of Gram-Positive Bacteria
Authors: Schuster George S. , Hayashi James A. , Bahn Arthur N.
Published: January 2020

The biological activity of
Odontomyces viscosus
, which has been reported to cause periodontal disease in hamsters, was examined. The microorganism was cultured anaerobically in Brain Heart Infusion broth, and the cells were harvested. The washed cells were injected intradermally into the abdomen of rabbits. After 72 hr, a well-defined, firm, raised nodule (about 1.0 by 1.5 cm) with an erythematous border was seen at the injection site. Suspensions of cell wall and cytoplasmic material were injected intradermally, and the lesions appeared only at the site of cell wall injection. The cell walls, which were then treated with trypsin, pepsin, and ribonuclease, again produced the characteristic lesion. These nodular dermal lesions persisted for a minimal time of 10 days. The enzymatically treated cell walls were then hydrolyzed with 1
n
HCl, and such hydrolysis up to 1 hr failed to alter the toxic activity of the cell walls. Similar dermal nodular lesions were obtained by injection of enzymatically treated cell walls of strains of
Staphylococcus aureus, Streptococcus
groups B, C, E, F, K,
Lactobacillus casei
, and
Actinomyces israelii
. Treatment with hot and cold trichloroacetic acid solutions and proteolytic enzymes, or with formamide, yielded insoluble fractions which produced the characteristic nodular lesions. The size of the lesion resulting from injection of these fractions was proportional to the amount of the injected material. The active fraction, which does not appear susceptible to hydrolysis by lysozyme, is thought to be cell wall mucopeptide. Histological studies showed skin abscesses due to the toxic reaction; however, in addition to the acute inflammatory reaction, there was local eosinophilia.
Antimicrobial Activity of Aflatoxins
Authors: Arai Tadashi , Ito Tatsuya , Koyama Yasumasa
Published: January 2020

Antimicrobial activity of a crude aflatoxin preparation and of aflatoxin B
1
was studied. They were found inactive against common gram-positive and gram-negative bacteria at a concentration of 100 μg/ml. Both samples of aflatoxin did, however, exhibit antimicrobial activity, though narrow and limited, against various strains of
Streptomyces
and
Nocardia
. The antibiotic action of aflatoxin B
1
was confirmed by bioautogram after thin-layer chromatography. Among seven strains of microorganisms, including aflatoxin-sensitive and -resistant strains,
N. asteroides
IFM 8 was found to reduce aflatoxin B
1
, in addition to other minor fluorescent components in the crude preparation.
Mode of Action of Antibiotic U-20,661
Authors: Reusser Fritz
Published: January 2020

Antibiotic U-20,661 was shown to inhibit predominantly deoxyribonucleic acid (DNA)-directed ribonucleic acid (RNA) synthesis by binding to the double-stranded DNA template. Specific binding to DNA was verified by difference spectroscopy, reversal of the RNA polymerase inhibitory effect by increasing concentrations of DNA template, and by moderately increasing the melting temperature of double-stranded DNA in the presence of the antibiotic. The RNA polymerase reaction primed with synthetic poly dAT was inhibited considerably, but not completely even with high concentrations of antibiotic. Thus, the agent might bind to adenine or thymidine or both bases in the double-stranded DNA helix.
Identification of Staphylococcal Hemolysins by an Electrophoretic Localization Technique
Authors: Haque Riaz-Ul
Published: January 2020

A technique for identifying and characterizing staphylococcal hemolysins by first separating them electrophoretically in barbital-buffered agar gel (
p
H 8.4) at 5 ma/cm for 2 hr and then determining their hemolytic activities by exposing them to human, horse, rabbit, and sheep erythrocytes is described. The α-hemolysin produced by a White variant of the Wood 46 strain of
Staphylococcus aureus
migrated 18 mm towards the cathode, and it lysed horse, rabbit, and sheep erythrocytes, whereas a Clear variant of the Wood 46 strain of
S. aureus
produced a lysin which migrated similarly to the α-hemolysin but lysed only rabbit cells. This latter lysin was tentatively named α
1
-lysin. This strain of
S. aureus
also produced β-hemolysin which migrated 36 mm towards the cathode and lysed sheep cells. β-Hemolysin produced by some strains of
S. aureus
showed considerable tailing during electrophoresis, whereas β-hemolysin produced by other strains of
S. aureus
migrated as a well-defined peak. A lysin migrating 11 mm towards the anode was probably δ-lysin. It was, however, not produced in sufficient concentration when the cultures were grown in semisolid medium.
Pathway of Glucose Fermentation in Relation to the Taxonomy of Bifidobacteria
Authors: de Vries Wytske , Stouthamer A. H.
Published: January 2020

Cell-free extracts of 17 strains of
Bifidobacterium bifidum
(
Lactobacillus bifidus
) were examined for the presence of aldolase, glucose-6-phosphate dehydrogenase, and fructose-6-phosphate phosphoketolase. All strains turned out to lack aldolase, an enzyme unique to glycolysis, and glucose-6-phosphate dehydrogenase, characteristic of the hexosemonophosphate pathway. In all strains, fructose-6-phosphate phosphoketolase could be demonstrated. It can be concluded that bifidobacteria ferment glucose via a pathway which is different from those found in members of the genus
Lactobacillus
. The results strengthen the previous suggestions that classification of the bifidobacteria in the genus
Lactobacillus
is not justified.
Kinetics of Growth of Individual Cells ofEscherichia coliandAzotobacter agilis
Authors: Harvey R. J. , Marr Allen G. , Painter P. R.
Published: January 2020

Escherichia coliandAzotobacter agiliswere grown in minimal media until a steady state was established. The distribution of cell size was determined electronically. From the equation of Collins and Richmond, the growth rate of individual cells was computed as a function of size. The main features of the growth of individualE. coliandA. agiliscells revealed by this work were: the specific growth rate decreased at the time of division, and both the absolute and specific growth rates increased between divisions. The frequency function of interdivision times was computed and was found to be positively skewed with a coefficient of variation of approximately 0.3. The results supported the hypothesis of Koch and Schaechter that the size of an individual cell at division is highly regulated.
Synthesis of Saturated Long Chain Fatty Acids from Sodium Acetate-
1-C
14
by
Mycoplasma
Authors: Pollack J. D. , Tourtellotte M. E.
Published: January 2020

Three strains of
Mycoplasma, M. laidlawii
A and B, and
Mycoplasma
sp. A60549, were grown in broth containing sodium acetate-
1-C
14
. The methyl esters of the phospholipid fatty acids of harvested radioactive cells were prepared and identified by comparison of their mobilities to known radioactive fatty acid methyl esters by use of a modified reversed-phase partition-thin layer chromatographic technique. No radioactive methyl oleate or methyl linoleate was detected. Compounds migrating as radioactive methyl myristate, stearate, palmitate, and, with less certainty, laurate and octanoate were detected. The qualitative findings for all three organisms appeared similar.
M. laidlawii
B synthesized a radioactive substance, presumably a saturated fatty acid detected as the methyl ester derivative, which migrated in a position intermediate to methyl myristate-
1-C
14
and methyl palmitate-
1-C
14
. This work indicates that
M. laidlawii
A and B and
Mycoplasma
sp. A60549 are capable, in a complex medium containing fatty acids, of synthesizing saturated but not unsaturated fatty acids entirely or in part from acetate.
Initiation of Infection by Deoxyribonucleic Acid From Bacteriophage λ
Authors: Elseth Gerald D. , Simmons John R.
Published: January 2020

Kinetic studies conducted on the early stages of infection of
Escherichia coli
K-12 by deoxyribonucleic acid (DNA) isolated from bacteriophage λ indicate a rapid adsorption of the phage DNA to receptor sites at the bacterial surface prior to deoxyribonuclease-insensitive incorporation. A direct relationship found between the number of DNA molecules adsorbed per bacterium and the multiplicity of helper phage infection indicates a requirement for helper function during the attachment process. An apparent lack of attachment specificity with regard to the source of the DNA preparation, to the size of the inhibiting fragment, to the base ratio of the inhibiting DNA molecule, and to “cohesive” ends suggests a nonspecific interaction between the infectious DNA and the sites of helper phage attachment.
Effect of the Hemolysin of
Pseudomonas aeruginosa
on Phosphatides and on Phospholipase c Activity
Authors: Kurioka Susumu , Liu Pinghui V.
Published: January 2020

The hemolysin of
Pseudomonas aeruginosa
was found to function as a detergent in solubilizing various phosphatides. Incorporation of the hemolysin into reaction mixtures containing phosphatides and phospholipase c significantly increased the rates of enzyme activities. Stimulation of enzyme activity was most likely due to improved dispersion of the substrates.
Effects of Mitomycin C on Macromolecular Synthesis in
Escherichia coli
Authors: Suzuki Hiromi , Kilgore Wendell W.
Published: January 2020

When cells of
Escherichia coli
B growing in a glucose-synthetic medium were treated with mitomycin C, the effects produced by the antibiotic varied, depending on the concentration. When the concentration was reduced to less than 0.1 μg/ml, the action of the antibiotic was bacteriostatic; cell elongation resulted, but no effect on the synthesis of cellular macromolecules was apparent. At higher levels (more than 5 μg/ml), mitomycin C was highly bactericidal and inhibited deoxyribonucleic acid synthesis almost completely. The exposure of growing cells to a bactericidal level of mitomycin C resulted also in a delayed inhibition of the synthesis of ribonucleic acid (RNA) and protein. The capacity of the treated cells to synthesize β-galactosidase inducibly in a medium free from a carbon source remained constant for the first 30 min and then was destroyed progressively with time. Prolonged incubation with the bactericidal level of mitomycin C caused a degradation of cellular nucleic acids, particularly RNA. The degraded nucleic acid components were eventually released into the medium.
Episome-carried Surface Antigen K88 of
Escherichia coli
II. Isolation and Chemical Analysis
Authors: Stirm Stephan , Ørskov Frits , Ørskov Ida , Mansa Bendt
Published: January 2020

The K88 antigen was carried by episomal transfer to D282, a nonmotile
Escherichia coli
strain without K antigen. D520, obtained by this episomal transfer, was used for the extraction of K88 antigen. It was shown by the agar gel precipitation technique that some K88 antigen was released from D520 into suspending aqueous medium. The amount of liberated material was increased by gentle heating (60 C) or treatment in a Waring Blendor. The antigen was obtained from the extracts in a purified form by making use of its insolubility between
p
H 3.5 and 5.5 and of its high sedimentation rate (
S
0
20,w
= 36.7
S
). The homogeneity of the material was demonstrated by agar gel precipitation with D520 antiserum, by analytical ultracentrifugation, and by moving-boundary electrophoresis. Chemical analysis revealed that K88 is a pure protein containing all the common amino acids with the exception of cysteine-cystine. Purified K88 selectively precipitated the K88 antibodies from D520 antiserum and was shown to be immunogenic in rabbits.
Changes in Spores of
Bacillus megaterium
Treated with Thioglycolate at a Low
p
H and Restoration of Germinability and Heat Resistance by Cations
Authors: Rowley Durwood B. , Levinson Hillel S.
Published: January 2020

Spores of
Bacillus megaterium
QM B1551 treated with thioglycolate (0.4
m
,
p
H 2.6) at 50 C for 30 min remained refractile, but they became stainable, lysozymesensitive, and nonviable, and they lost dipicolinic acid (DPA). The loss of DPA and of viability were functions of the time and temperature of exposure to thioglycolate. Spores treated with thioglycolate at a lower temperature and for a shorter time (30 C, 5 min) retained DPA, viability, and nonstainability. Although these spores also retained their resistance to γ radiation and to lysozyme, they lost thermo-resistance. Their percentage of germination over a 2-hr period in glucose was markedly reduced. Germinability and heat resistance were restored by exogenous cations, suggesting that the thioglycolate treatment (30 C, 5 min) resulted in the loss of spore ions essential for normal germination in glucose and for heat resistance.
Nature of the Repair of Methyl Methanesulfonate-Induced Damage in
Bacillus subtilis
Authors: Reiter H. , Strauss B. , Robbins M. , Marone R.
Published: January 2020

A nuclease present in extracts of
Bacillus subtilis
inserts breaks in deoxyribonucleic acid (DNA) treated with the monofunctional alkylating agent, methyl methanesulfonate (MMS), but the nature of the sites within the alkylated macromolecule at which these breaks occur is not known. DNA extracted from
B. subtilis
cells that have recovered from MMS damage has lost its susceptibility to enzyme action. The recovery process is accompanied by some DNA breakdown and by the incorporation of thymidine. Some recovery from ultraviolet irradiation (UV) and MMS occurred in organisms starved for thymine or adenine, but UV recovery was stimulated by their addition. It is possible that MMS recovery proceeds by a process of excision and repair similar to, but not identical with, UV repair.
Response of Cell Walls ofEscherichia colito a Sudden Reduction of the Environmental Osmotic Pressure
Authors: Bayer M. E.
Published: January 2020

The rate of survival after osmotic shocks was found to be dependent on the state of growth. When growing logarithmically,Escherichia coliwas about 20 to 100 times more sensitive to an abrupt decrease of the environmental osmotic pressure than when it was in the stationary phase. Subjecting rapidly growing cells to such a treatment caused fingerlike extrusions to emerge from the bacterial wall. Our results suggest that underneath these extrusions the rigid layer of the wall contains weak areas which appear as discontinuities or gaps when viewed in an electron microscope. After exposure to osmotic shock, the gaps became wider. We concluded that the gaps represent sites of mucopolymer synthesis where the rigid structure has temporarily been opened by hydrolytic enzymes to allow for the insertion of new wall material into the older portions of the wall.
Influence of the Intestinal Flora on the Development of Immune Reactions in Infants
Authors: Lodinova R. , Jouja V. , Lanc A.
Published: January 2020

Breast-fed and artifically fed infants are in contact with the O antigen of
Escherichia coli
from the first days after birth. From the mother, the infant obtains antibodies against nonpathogenic
E. coli
strains in low titer, and the infant begins to form its own antibodies during the 2nd month of life. The transition is known to be continuous even though the transferred antibodies could not be differentiated from the infant's own antibodies. Contact with endotoxin caused sensitization which was detected by the skin test at about 2.5 months, and thereafter the skin test data correlated with the presence of serum antibodies against endotoxin. The newborn infant can be colonized with a different
E. coli
serotype; such an antigenic stimulus evokes the formation of antibodies sooner and at a significantly higher titer than (i) the level of maternal antibodies transferred or (ii) the infant's antibodies normally formed later on against other random
E. coli
serotypes.
Recovery of Donor Deoxyribonucleic Acid Marker Activity from Eclipse in Pneumococcal Transformation
Authors: Ghei Om K. , Lacks S. A.
Published: January 2020

After the uptake of deoxyribonucleic acid (DNA), donor marker-transforming activity is temporarily lost. Restoration of the activity by annealing in vitro supports the idea that donor DNA is single-stranded at this stage. Kinetics of in vivo recovery from eclipse were examined for various markers at three temperatures. Sigmoidal recovery curves at lower temperatures indicate that the process consists of several steps. Rate of recovery was found to depend on the nature of the donor marker. Single-site markers recover much more rapidly than multisite markers corresponding to recipient deletions. Single-site markers vary somewhat in recovery rate, with rapidity of recovery inversely related to integration efficiency. Appearance of a recombinant-transforming activity lags only slightly behind recovery of its constituent donor marker.
Factors Affecting the Pathways of Glucose Catabolism and the Tricarboxylic Acid Cycle in
Pseudomonas natriegens
Authors: Cho H. W. , Eagon R. G.
Published: January 2020

Less than 50% of theoretical oxygen uptake was observed when glucose was dissimilated by resting cells of
Pseudomonas natriegens
. Low oxygen uptakes were also observed when a variety of other substrates were dissimilated. When uniformly labeled glucose-
14
C
was used as substrate, 56% of the label was shown to accumulate in these resting cells. This material consisted, in part, of a polysaccharide which, although it did not give typical glycogen reactions, yielded glucose after its hydrolysis. Resting cells previously cultivated on media containing glucose completely catabolized glucose and formed a large amount of pyruvate within 30 min. Resting cells cultivated in the absence of glucose catabolized glucose more slowly and produced little pyruvate. Pyruvate disappeared after further incubation. In this latter case, experimental results suggested (i) that pyruvate was converted to other acidic products (e.g., acetate and lactate) and (ii) that pyruvate was further catabolized via the tricarboxylic acid cycle. Growth on glucose repressed the level of key enzymes of the tricarboxylic acid cycle and of lactic dehydrogenase. Growth on glycerol stimulated the level of these enzymes. A low level of isocitratase, but not malate synthetase, was noted in extracts of glucose-grown cells. Isocitric dehydrogenase was shown to require nicotinamide adenine dinucleotide phosphate (NADP) as cofactor. Previous experiments have shown that reduced NADP (NADPH
2
) cannot be readily oxidized and that pyridine nucleotide transhydrogenase could not be detected in extracts. It was concluded that acetate, lactate, and pyruvate accumulate under growing conditions when
P. natriegens
is cultivated on glucose (i) because of a rapid initial catabolism of glucose via an aerobic glycolytic pathway and (ii) because of a sluggishly functioning tricarboxylic acid cycle due to the accumulation of NADPH
2
and to repressed levels of key enzymes.
Purification and Properties of
Streptococcus lactis
β-Galactosidase
Authors: McFeters G. A. , Sandine W. E. , Elliker P. R.
Published: January 2020

β-Galactosidase of
Streptococcus lactis
7962 was partially purified, and its properties were studied. Enzyme from only this strain of numerous lactic streptococci tested was stable in cell exudates prepared by various means. Cell-free extracts of the 7962 strain were prepared by sonic treatment of washed cells previously grown in presence of lactose to fully induce enzyme synthesis. Protamine sulfate precipitation of the nucleic acids and ammonium sulfate precipitation of protein were used for partial purification of the enzyme. The resulting enzyme, when resuspended in cold (5 C) phosphate buffer, was extremely labile. However, ammonium sulfate in high concentrations (0.85
m
) stabilized and stimulated β-galactosidase activity. Sephadex G-200 gel filtration was used to achieve further purification and to monitor homogeneity of the enzyme. Separation of the β-galactosidase in buffer at 5 C yielded an enzyme elution pattern showing two peaks of activity. However, addition of the enzyme solution in 0.85
m
ammonium sulfate to the column equilibrated with the same salt concentration yielded only one peak of enzyme activity. The data suggested that the native enzyme was dissociating into active subunits which were stabilized in the presence of the ammonium sulfate.
Structural Transitions in Ribonucleic Acid During Ribosome Development
Authors: Sypherd Paul S. , Fansler Bradford S.
Published: January 2020

Amino acid deprivation of a “relaxed” auxotroph of
Escherichia coli
results in the accumulation of protein-deficient, immature ribosomes (“relaxed particles”). The ribonucleic acid (RNA) of these particles was shown to differ from mature ribosomal RNA in both sedimentation characteristics and in elution from columns of methylated albumin-keiselguhr. When relaxed particles were allowed to become converted to mature ribosomes, the unique properties of the RNA were lost, and this RNA became indistinguishable from mature RNA. The conversion of relaxed particles to ribosomes did not involve degradation and resynthesis of RNA. It is concluded that ribosomal RNA undergoes a configurational transition during ribosome development, and that this transition is not the result of changes in the primary structure of the RNA.
Use of Analogues and the Substrate-Sensitivity of Mutants in Analysis of Purine Uptake and Breakdown in
Aspergillus nidulans
Authors: Darlington A. J. , Scazzocchio C.
Published: January 2020

Aspergillus
mutants resistant to various purine analogues (purine, 8-azaguanine, 2-thioxanthine, and 2-thiouric acid) are defective in at least one step of purine uptake or breakdown. The properties of these mutants show that there are two uptake systems for purines, one which mediates the uptake of hypoxanthine, guanine, and adenine, and the other, xanthine and uric acid. Allantoinase-less strains are sensitive to the toxic effects of allantoin accumulation. They are severely inhibited when grown in the presence of naturally occurring purines. Mutant strains derived from these, resistant to naturally occurring purines, may be isolated. These are either wild-type revertants, or carry a second metabolic block in the uptake or breakdown of purines. The properties of these double mutants confirm the interpretation of the nature of the analogue-resistant mutants.
Gluconate Metabolism in
Escherichia coli
Authors: Eisenberg Robert C. , Dobrogosz Walter J.
Published: January 2020

On the basis of information available in the literature, gluconate dissimilation in
Escherichia coli
is thought to occur via the hexose monophosphate pathway. Evidence is presented in this study that gluconate is catabolized in this organism via an inducible Entner-Doudoroff pathway. This evidence is based on chromatographic examination of end products produced from
14
C-labeled gluconate or glucose, distribution of
14
C in the carbon atoms of pyruvate formed from specifically labeled
14
C
-glucose and
14
C
-gluconate, and the ability of cell-free extracts to produce pyruvate from 6-phosphogluconate. Degradation of gluconate by an Entner-Doudoroff pathway occurred simultaneously with a glycolytic cleavage of glucose. A relationship between gluconate-induced, Entner-Doudoroff pathway activity and catabolism of glucose in
Escherichia coli
and other bacterial species is discussed.
Metabolic Injury to Bacteria II. Metabolic Injury Induced by Distilled Water or Cu
++
in the Plating Diluent
Authors: MacLeod Robert A. , Kuo S. C. , Gelinas Roger
Published: January 2020

When distilled water from a tin-lined still served as the plating diluent, cells of
Aerobacter aerogenes
developed symptoms of metabolic injury as evidenced by increased counts on supplemented, as compared with minimal, plating medium. Cysteine was as effective as yeast extract as a supplement to the minimal medium in increasing the viable count. Mg
++
and, to a lesser extent, phosphate buffer at the concentrations tested protected unfrozen cells, but not cells which had been frozen and stored, against the loss of capacity to grow on minimal medium. When the plating diluent consisted of distilled water redistilled in an all-glass still, the symptoms of metabolic injury did not appear. Spectrographic analysis revealed the presence of 10
−7
m
Cu
++
in the distilled water, and Cu
++
added to redistilled water serving as the plating diluent reproduced the metabolic injury effects induced by distilled water. It was concluded that freezing and storage damaged the cell membrane, rendering it more penetrable by toxic elements which were thereby enabled to act at sites in the cell where Mg
++
and other solutes in the plating diluent could not serve as effective antagonists. Increased recovery of cells on supplemented medium could be ascribed to the capacity of the supplements to remove toxic elements which had become bound to the cells during suspension in the plating diluent.
Mode of Filamentous Growth of
Leucothrix mucor
in Pure Culture and in Nature, as Studied by Tritiated Thymidine Autoradiography
Authors: Brock Thomas D.
Published: January 2020

Mode of growth of
Leucothrix mucor
filaments was measured by autoradiography with tritiated thymidine. Studies were performed on
L. mucor
in pure cultures in free suspension, as an epiphyte of pure cultures of the red alga
Antithamnion sarniense
, and as an epiphyte of red algae in the sea. Statistical analyses of the distribution of growing cells was done by use of the nonparametric One-Sample Runs Test and a Cluster analysis adapted from quadrat analyses of plant ecologists. No evidence of preferential growth at base or tip of
L. mucor
filaments was obtained in any of these studies. However, in nature, but not in the laboratory, there were regions of
L. mucor
filaments which were nongrowing or dormant. Such nongrowing regions could incorporate tritiated glucose.
Immunofluorescence Identification ofMycoplasmaon Agar by Use of Incident Illumination
Authors: Del Giudice Richard A. , Robillard Norman F. , Carski Theodore R.
Published: January 2020

The fluorescent-antibody method has been employed for the rapid identification ofMycoplasmacolonies growing on agar plates. The method was found to be effective for detection of mixtures ofMycoplasmaserotypes growing on primary isolation plates. The technique also helped to define the presence of mycoplasmas which did not produce typical colonies. It was also possible to identifyMycoplasmacolonies overgrown by bacterial or fungal contaminants. Conjugates directed against 10 distinctMycoplasmaserotypes have been successfully employed in this system. One of the serotypes is a human oral isolate which has not been previously characterized.
Relation Between Iron Uptake,
p
H of Growth Medium, and Penicillinase Formation in
Staphylococcus aureus
Authors: Cohen Sidney , Sweeney Helen M. , Leitner Felix
Published: January 2020

The uptake of iron and the formation of penicillinase was examined in cultures of wild-type
Staphylococcus aureus
. Uptake of iron was about twice as great at
p
H 4.7 as at
p
H 7.4 At
p
H 4.7, increase in iron uptake in the range of 1.0 to 4.0 μg per mg of bacterial protein was associated with a progressive increase in the rate of penicillinase formation, but a direct correlation between cellular iron content and rate of enzyme formation was not demonstrated. Addition of iron to deferrated medium enhanced penicillinase formation at
p
H 6.5 to 7.4 two- to fourfold in cultures induced with benzylpenicillin and in uninduced cultures. To demonstrate an effect on the uninduced cells, it was necessary to increase iron uptake by preliminary incubation of cells with iron in buffer. Calcium and certain other ions depressed iron uptake at acidic and at neutral
p
H, and, presumably as a result of this action, depressed the formation of penicillinase. Iron did not enhance penicillinase formation at
p
H 4.7 by two penicillinase constitutive mutants nor by wild-type cells undergoing induction at
p
H 6.5 by cephalosporin C or methicillin. After removal of cephalosporin C or methicillin during an early phase of induction, residual synthesis of enzyme was increased by prior uptake of iron. The results are considered compatible with the concept that uptake of iron, especially at acidic
p
H, interferes with the formation or function of penicillinase repressor.
Drug Resistance of Enteric Bacteria IX. Distribution of R Factors in Gram-negative Bacteria from Clinical Sources
Authors: Mitsuhashi Susumu , Hashimoto Hajime , Egawa Ryuki , Tanaka Tokumitsu , Nagai Yutaka
Published: January 2020

Many isolates belonging to the
Enterobacteriaceae
were collected in 1965 from the inpatients at geographically scattered hospitals in Japan. Among 2,650
Shigella
strains examined, 58.4% were found to be drug-resistant; 95.0% of these resistant strains were multiply resistant. Among 434 resistant strains examined, 81% carried R factors that were transferable by cell-to-cell contact. Of 160 isolates of other enteric bacteria, drug-resistant strains included 84.2% of the
Escherichia coli
, 93.0% of the
Klebsiella
, and 90.0% of the
Proteus
cultures. Among these resistant strains, 70.3% of the
E. coli
, 66.7% of the
Klebsiella
, and 52.0% of the
Proteus
were multiply resistant. Of these resistant strains, 84.0% of the
E. coli
, 88.0% of the
Klebsiella
, and 50.0% of the
Proteus
strains carried R factors. These results indicate that R factors are widespread among gram-negative bacteria of clinical significance.
Detection of Clostridial Hemolysin Formed In Vivo
Authors: Noyes Howard E. , Easterling Ronald
Published: January 2020

Experimental clostridial myonecrosis closely resembling gas gangrene was produced in goats by the intramuscular injection of washed clostridia suspended in adrenalin. The preparation provides a model for the study of clostridial myonecrosis that is relatively isolated from preceding trauma. A new test for the demonstration of clostridial exotoxins, the hemolysin indicator plate test, was described. This test gave reliable results within 6 hr, and only minute quantities of test material were required. Application of this test to would exudates of goats with experimental clostridial myonecrosis demonstrated the presence of the γ toxin of
Clostridium novyi
, α toxin of
C. septicum
, and the α toxin of
C. perfringens
in exudates from animals injected with washed
Clostridium
bacilli suspended in adrenalin. Exudates from goats injected with
C. perfringens
were lethal for mice and produced necrosis of guinea pig skin typical of
C. perfringens
. The convincing demonstration of clostridial exotoxins formed in vivo in this experimental model could be the basis for definition of clostridial exotoxin actions which have evaded study in the past.
Biosynthesis of Phenylalanine from Phenylacetate by
Chromatium
and
Rhodospirillum rubrum
Authors: Allison Milton J. , Robinson Isadore M.
Published: January 2020

Cultures of
Chromatium
strain D and
Rhodospirillum rubrum
incorporated
14
C from phenylacetate-
1
-
14
C
during anaerobic growth. The radioactivity in the protein fraction of cells was mainly in phenylalanine. Phenylalanine from
Chromatium
cells grown in phenylacetate-
1
-
14
C
was labeled at carbon 2. Incorporation of phenylacetate by
Chromatium
was decreased in the presence of exogenous phenylalanine, and de novo synthesis of phenylalanine from bicarbonate was less in medium containing either phenylalanine or phenylacetate. These organisms, and also certain anaerobic rumen bacteria, apparently carboxylate phenylacetate to synthesize the phenylalanine carbon skeleton. The mechanism of the carboxylation is unknown; however, it appears to be dependent upon anaerobic conditions, since
R. rubrum
did not synthesize phenylalanine from phenylacetate during aerobic growth in the dark.
Melanins and Resistance of Fungi to Lysis
Authors: Bloomfield B. J. , Alexander M.
Published: January 2020

Hyphal walls of
Aspergillus phoenicis
and
Sclerotium rolfsii
are composed of large amounts of glucose- and
N
-acetylhexosamine-containing polysaccharides, and the walls are extensively digested by streptomycete culture filtrates or by a mixture of purified chitinase and β-(1 → 3) glucanase preparations with the release of the monomeric units.
A. phoenicis
conidial walls also contain polymers of glucose and
N
-acetylhexosamine, but these walls are resistant to digestion by microorganisms or the enzyme combination active on the hyphae. When the melanin-containing spicules were removed from the spore surface, however, the chitinase and glucanase partially digested the underlying structural components. Microorganisms decomposing hyphal walls of
S. rolfsii
did not attack the melanin-covered sclerotia produced by this fungus. No microorganism capable of lysing two fungi,
Rhizoctonia solani
and
Cladosporium
sp., producing hyphae containing abundant melanin was found. The ecological significance of these findings and possible mechanisms for the protective influence associated with melanins are discussed.
Mechanisms of Regulation of Urease Biosynthesis in
Proteus rettgeri
Authors: Magaña-Plaza I. , Ruiz-Herrera J.
Published: January 2020

Urease of
Proteus rettgeri
is an inducible enzyme synthesized specifically in the presence of urea; urea analogues did not act as inducers. Once initiated, the biosynthesis of the enzyme proceeded as a constant fraction of the total protein formed. The rate of urease formation was affected by the carbon source used. In comparison with glycerol, glucose inhibited enzyme synthesis. The addition of ammonium ions to the inducing medium also decreased the rate of urease biosynthesis, and when ammonium ions were present urease activity and urea transport across the cell membrane were inhibited. A kinetic analysis of urease inhibition by ammonium ions, by use of a partially purified preparation of urease, showed that it was a competitive inhibition.
Effect of Oxygen on Viability and Substrate Utilization in
Chromatium
Authors: Hurlbert R. E.
Published: January 2020

Chromatium
D can be exposed to oxygen for prolonged periods without any loss in motility or viability. Oxygen did not affect the rate of thiosulfate disappearance from the media, the oxidation of the inner sulfur atom of thiosulfate to sulfate, or the conversion of the outer sulfur atom of thiosulfate to intracellular sulfur, but it did inhibit the oxidation of intracellular sulfur to sulfate. Oxygen partially inhibited the uptake of pyruvate from the medium, but had little effect on the uptake of acetate. The distribution of label from pyruvate-
2
-
14
C
into various cell fractions under aerobic conditions differed only slightly from that obtained under anaerobic conditions. Cells utilizing acetate-
2
-
14
C
aerobically converted the majority of the metabolized acetate into a cell fraction with the solubility characteristics of poly-β-hydroxybutyric acid, whereas under anaerobic conditions the acetate was distributed throughout the other cell fractions. Oxygen completely prevented the synthesis of bacteriochlorophyll.
Effect of Ethylenediaminetetraacetic Acid-Tris(hydroxymethyl)aminomethane on Release of the Acid-soluble Nucleotide Pool and on Breakdown of Ribosomal Ribonucleic Acid in
Escherichia coli
Authors: Neu Harold C. , Ashman Donald F. , Price T. Duane
Published: January 2020

Brief treatment of
Escherichia coli
with 2 × 10
−4
m
ethylenediaminetetraacetic acid (EDTA)-0.12
m
tris(hydroxymethyl)aminomethane (Tris),
p
H 8.0, or 0.12
m
Tris alone resulted in the release of the acid-soluble nucleotide pool at 3 or 23 C. Exposure to EDTA-Tris for up to 90 min at 3 C did not result in the release of increasing amounts of 260-mμ-absorbing material. At 23 and 37 C, EDTA-Tris resulted in a steady increase in acid-soluble 260-mμ-absorbing material. Previous growth environment did not alter the release. There appeared to be degradation of 23
S
ribonucleic acid (RNA) after 10 min of exposure at 23 C. In addition, there was degradation of nucleotides to nucleosides and bases. This occured either within the cells with altered permeability or in the periplasmic space. This occurred in the presence of EDTA and Tris but was not seen with EDTA-phosphate. The mechanism of this degradation is unclear, since it occurs in ribonuclease I-deficient strains. Exposure to Tris buffer for long periods of time at 23 C resulted in release of the nucleotide pool and in degradation of RNA and nucleotides. These studies point out that the EDTA-Tris effect on
E. coli
must be divided into two parts, an early (4 to 5 min) change in permeability and a later phase of actual RNA breakdown and nucleotide degradation. Studies utilizing EDTA and Tris as agents altering permeability must thus be viewed with caution. Although the cells are viable, they have lost their acid-soluble nucleotide pool and have undergone degradation of some ribosomal RNA.
Inhibition ofShigella flexneriby the Normal Intestinal Flora I. Mechanisms of Inhibition byKlebsiella
Authors: Hentges David J.
Published: January 2020

Growth curves were plotted forShigella flexneriandKlebsiella(Aerobacter aerogenes) multiplying in pure and mixed culture. In mixed culture,KlebsiellainhibitedShigella. Exponential growth was interrupted andShigellaentered into a logarithmic death phase. An analysis of cultures at the time inhibition occurred revealed that formic and acetic acids produced byKlebsiellawere responsible for the inhibition ofShigella.Klebsiellastrongly reduced the culture medium. The volatile fatty acids, operating under reduced conditions, exerted a bactericidal effect onShigella. Results are discussed with reference to the possible role of volatile fatty acids as factors responsible forShigellainhibition in vivo.
Growth Inhibition Test for Identification ofMycoplasmaSpecies Utilizing Dried Antiserum-Impregnated Paper Discs
Authors: Stanbridge Eric , Hayflick Leonard
Published: January 2020

The growth inhibition test for identifyingMycoplasmaspecies has been modified by drying antibody-impregnated paper discs at 5 C. When stored at −20 C, these discs have been found to retain their inhibitory activity for longer than 7 months. Since these discs can be stored for long period of time, significant advantages over present methods result. When, for example, discs are arranged on a ring, a single test can be used for the identification of an unknown human species. Valuable antisera can be distributed to other laboratories on paper discs in much less volume than can fluid antiserum. Considerable savings of time result from prior preparation of many discs that can then be stored and used over a long period of time. The growth-inhibiting antibody is stable, and the activity is not enhanced by a heat-labile accessory factor from fresh guinea pig serum which increases the antibody titer in the metabolic inhibition test.
Flagellated Actinomycetes
Authors: Higgins M. L. , Lechevalier Mary P. , Lechevalier H. A.
Published: January 2020

Shadowed motile elements from actinomycetes were observed with an electron microscope. Included were three strains of
Actinoplanes
, two of
Ampullariella
, two of
Dermatophilus
, two of
Spirillospora
, and four of “
Nocardia
”
turbata
. In addition, three types of previously undescribed actionmycetes were represented: (i) the C
4
group (four strains) forming substrate mycelium breaking into motile rods; (ii) strain 9-41, forming
Microellobosporia
-like sporangia with motile spores; and (iii) strain P
2
, forming aerial hyphae releasing motile cocci when put in water. All the known chemical cell wall types of actinomycetes except the
Nocardia asteroides
type and the
Actinomyces israeli
type were represented in this array of motile actinomycetes. Motile elements were, depending on the genus, cocci, rods (often curved), or pyriform. Flagella were always in tufts (or single), never peritrichous. A relationship seems to exist between the location of the tuft and the cell wall composition. The spores of one strain of
Actinoplanes
were herniated, thus resembling plasmoptysis forms of bacteria.
Chemical Composition of the Cell Walls of
Bacillus stearothermophilus
Authors: Sutow Allan B. , Welker N. E.
Published: January 2020

Cell walls were isolated by mechanical disruption of mid-log phase cells of
Bacillus stearothermophilus
NCA 1503-4R grown in Trypticase-yeast extract-fructose medium at 55 C. The cell walls were purified by treatment with sodium dodecyl sulfate (SDS) and incubation with deoxyribonuclease and trypsin. The cell wall peptidoglycan contained glucosamine, muramic acid, α, ε-diaminopimelic acid, and glutamic acid. Low amounts of glycine, galactosamine, serine, aspartic acid, lysine, and valine were also present. The relative mole ratios of glutamic acid–α, ε-diaminopimelic acid–glycine–alanine were 1.00:1.26:0.08:1.55. The cell walls were free from ribonucleic acid and deoxyribonucleic acid and contained less than 0.2% chloroform-methanol extractable lipid and 0.09 μmole of phosphorus per mg of cell wall. Teichoic acid was not detected in the cell walls of this organism. Cell walls isolated without treatment with SDS contained 7.5% chloroform-methanol extractable lipid, 0.24 μmole of phosphorus per mg of cell wall, and relatively high concentrations of all amino acids. These results suggest that the extracted lipid is not a cell wall component per se, but a contaminant from the lipoprotein cell membrane.