bluuebunny/crossref_metadata_2025 huggingface dataset:
Accumulation of
14
C-Streptomycin by Streptomycin-sensitive and Streptomycin-resistant Group H Streptococci
Authors: Perry Dennis
Published: January 2020

Three streptomycin-resistant mutants of group H streptococcus, strain Challis, were examined for ability to accumulate
14
C-streptomycin. Although the mutants exhibited different levels of transformation, only the streptomycin-sensitive parent Challis strain accumulated significant amounts of
14
C-streptomycin. It appears that impermeability to streptomycin does not necessarily result in reduction or loss of transformability. The amount of label accumulated by strain Challis was correlated with a loss of viability. In addition, accumulation of label was influenced by the concentration of
14
C-streptomycin, the time of exposure, and the type of medium employed.
Neurospora
Mutant Exhibiting Hyperproduction of Amylase and Invertase
Authors: Gratzner Howard , Sheehan D. N.
Published: January 2020

A mutant strain of
Neurospora crassa
has been isolated which is derepressed for amylase and β-fructofuranosidase (invertase). Large amounts of the two enzymes were secreted into the culture medium upon depletion of exogenous carbon source. The resulting increases of the two extracellular enzymes were prevented by actinomycin D, cycloheximide, and glycerol. The starving cells of the mutant strain produced amylase and invertase de novo, as evidenced by incorporation of radioactive amino acids into the enzymes. Preliminary genetic studies indicate that these elevated enzyme levels described are due to a single gene mutation.
Molecular Basis of Transient Repression of β-Galactosidase in
Escherichia coli
Authors: Tyler Bonnie , Magasanik Boris
Published: January 2020

The molecular basis of transient repression of β-galactosidase by glucose was examined. This repression acted only at the level of transcription. Apparently, it was not mediated by the
I
-gene product. Analysis of single cells in a culture subjected to transient repression showed that essentially all cells initially experienced repression and later became gradually resistant to repression.
Microbial Dissimilatory Sulfur Cycle in Acid Mine Water
Authors: Tuttle Jon H. , Dugan Patrick R. , Macmillan Carol B. , Randles Chester I.
Published: January 2020

Ferric, sulfate, and hydrogen ions are produced from pyritic minerals associated with coal as a result of autotrophic bacterial metabolism. Water carrying these ions accumulated behind a porous dam composed of wood dust originating at a log-cutting mill. As water seeped through the porous dam, it was enriched in organic nutrients which then supported growth and metabolism of heterotrophic bacteria in the water downstream from the dam. The heterotrophic microflora within and below the sawdust dam included dissimilatory sulfate-reducing anaerobic bacteria which reduce sulfate to sulfide. The sulfide produced caused the chemical reduction of ferric to ferrous ion, and black FeS precipitate was deposited on the pond bottom. A net increase in the
p
H of the lower pond water was observed when compared to the upper pond water. Microbial activity in the wood dust was demonstrated, and a sequence of cellulose degradation processes was inferred on the basis of sugar accumulation in mixed cultures in the laboratory, ultimately yielding fermentation products which serve as nutrients for sulfate-reducing bacteria. Some of the microorganisms were isolated and characterized. The biochemical and growth characteristics of pure culture isolates were generally consistent with observed reactions in the acidic environment, with the exception of sulfate-reducing bacteria. Mixed cultures which contained sulfate-reducing bacteria reduced sulfate at
p
H 3.0 in the laboratory with sawdust as the only nutrient. Pure cultures of sulfate-reducing bacteria isolated from the mixed cultures did not reduce sulfate below
p
H 5.5.
Serological Relationships of Type I Antigens of Group B Streptococci
Authors: Wilkinson Hazel W. , Moody Max D.
Published: January 2020

Some of the complex antigenic relationships of type I group B streptococci from various clinical sources were defined by means of immunodiffusion, absorption, and precipitin tests. Three predominant types are described: Ia, Ib, and Ii. Methods for preparing antisera for differentiating type I strains are presented.
Antistreptococcal Activity of Lactoperoxidase
Authors: Steele Wilbert F. , Morrison Martin
Published: January 2020

A study of the inhibition of the growth of
Streptococcus cremoris
972 by the enzyme lactoperoxidase has shown, in agreement with previous investigations, that the inhibition requires a source of both peroxide and thiocyanate. The thiocyanate may play more than one role. It stabilizes the very dilute solutions of lactoperoxidase employed in these studies, and its oxidation products may be involved in the inhibition. Binding of the enzyme by the microorganism is suggested by the fact that when the organism was preincubated with the enzyme and then in a medium free from the enzyme, but containing peroxide and thiocyanate, the growth of the organism was inhibited. This inhibition has all the properties of the enzyme-containing system. Although no dialyzable factor could be demonstrated to cause the inhibition, the inhibitory state involving peroxide, the enzyme, and thiocyanate survived for at least 60 min before cells were added to the medium. When catalase was present in the medium prior to the addition of the cells, the inhibition was completely reversed. It was only partially reversed if catalase was added a few moments after the addition of the cells. The data have been interpreted as indicating that the inhibition takes place rapidly and requires the formation of a quaternary complex of the cells, thiocyanate, peroxide, and the enzyme lactoperoxidase.
Effect of Infection with the Meningopneumonitis Agent on Deoxyribonucleic Acid and Protein Synthesis by Its L-Cell Host
Authors: Alexander Jennifer J.
Published: January 2020

Cycloheximide, which had already been shown to inhibit protein synthesis in Earle's L cells (mouse fibroblasts) without having any effect on the multiplication or protein synthesis inChlamydia psittaci(strain meningopneumonitis) infecting these host cells, also caused greater than 90% inhibition of deoxyribonucleic acid (DNA) synthesis in L cells after a 3-hr exposure to the drug. L cells infected with the meningopneumonitis agent and treated with cycloheximide were used to follow meningopneumonitis-specific DNA synthesis during intracellular growth of the parasite. The rate at which labeled precursors were incorporated into parasite DNA doubled every 2 hr. The effect of meningopneumonitis infection on L-cell DNA and protein synthesis was investigated in logarithmically growing and in stationary-phase (nondividing) populations of L cells. Host-specific DNA and protein synthesis appeared to be inhibited in infected L cells when compared with logarithmically growing control cells, whereas no inhibition was apparent when the comparison was made with stationary-phase control cells. The maximal amount of protein and DNA synthesis that occurred in meningopneumonitis-infected L cells was equal to the amount of DNA and protein synthesized in logarithmically growing, uninfected L cells. A possible explanation of these results is given.
Role of Erythrocytes and Serum in the Nutrition of
Rickettsia quintana
Authors: Myers William F. , Cutler Leonard D. , Wisseman Charles L.
Published: January 2020

Rickettsia quintana
grew readily on blood-agar base when the following conditions and supplements were supplied: (i) aerobic conditions; (ii) increased CO
2
tension; (iii) crystalline hemoglobin or hemin, but not protoporphyrin; and (iv) a colloidal “detoxifying agent,” such as starch or charcoal. Serum was not required nor did it enhance growth when all of the aforementioned components were supplied.
Effect of Specific Immune Mouse Serum on the Growth ofSalmonella enteritidisin Nonvaccinated Mice Challenged by Various Routes
Authors: Collins F. M.
Published: January 2020

Salmonella enteritidiswas injected intravenously, intraperitoneally, or subcutaneously into specific pathogen-free mice. The number of organisms in the blood, liver, spleen, peritoneal cavity, and draining inguinal lymph node was determined by daily enumeration. Opsonization of the organism with hyperimmune serum increased the rate of phagocytosis, resulting in rapid blood clearance together with an alteration in the relative numbers of organisms accumulating in the liver and spleen. Serum treatment also brought about a substantial increase in the number of bacteria killed during the first 60 min of the infection. However, the survivors of this initial period of inactivation then multiplied rapidly in the liver and spleen, ultimately resulting in the death of the animal from a generalized infection. Attempts to passively protect mice with hyperimmune serum were uniformly negative. The effects of treatment of the virulentS. enteritidiswith hyperimmune serum were consistent with the general thesis that cellular rather than humoral factors play the major role in the expression of an effective antibacterial immunity against salmonella infections.
Effect of Specific Immune Mouse Serum on the Growth ofSalmonella enteritidisin Mice Preimmunized With Living or Ethyl Alcohol-killed Vaccines
Authors: Collins F. M.
Published: January 2020

The effect of prior opsonization of virulentSalmonella enteritidison the growth of this organism in blood, liver, spleen, peritoneal cavity, and inguinal lymph node of specific pathogen-free mice prevaccinated with ethyl alcohol-killedS. enteritidisor livingS. gallinarumwas determined by daily enumeration. Both the vaccines and the challenge inocula were injected by the intravenous, intraperitoneal, or subcutaneous routes to determine the effect of variations in the vaccinating procedure on the level of immunity induced. The survival percentage observed in mice vaccinated with killed organisms varied extensively, depending on the route of challenge. However, simultaneous organ enumeration studies revealed that vaccination with killed organisms failed to prevent the growth of the challenge organism in vivo. On the other hand, virulentS. enteritidisinjected into mice vaccinated with livingS: gallinarumfailed to multiply and was subsequently eliminated. Immunity in these animals was so effective that a subcutaneously injected challenge did not spread beyond the regional node. Immunization with killed organisms slowed but was unable to prevent the spread of such a challenge beyond the draining node involved in the primary immune response. Neither the route of challenge nor the regimen used in the vaccination had any appreciable influence on the level of antibacterial immunity detected in the organs of the reticuloendothelial system at the time of challenge.
Phosphoenolpyruvate Carboxylation and Aspartate Synthesis in
Acetobacter suboxydans
Authors: Claus G. W. , Orcutt M. L. , Belly R. T.
Published: January 2020

Dialyzed extracts of
Acetobacter suboxydans
ATCC 621 catalyze
14
CO
2
assimilation in the presence of phosphoenolpyruvate and a divalent cation. The formation of
14
C-oxalacetate was demonstrated and found not to be dependent upon the presence of orthophosphate or diphosphonucleotides. Oxalacetate synthesis was stimulated by orthophosphate and inhibited by aspartate. All attempts to demonstrate a reversible carboxylation mechanism have failed.
14
C-aspartate was synthesized when phosphoenolpyruvate, H
14
Co
3
−
, pyridoxal phosphate, and glutamate were added to dialyzed extracts. Chromatographic and spectrophotometric analyses and chemical degradation further demonstrate the presence of a reversible aspartate aminotransferase. The function of oxalacetate synthesis in a bacterium that reportedly lacks an operative tricarboxylic acid cycle is discussed.
Product Induction in
Pseudomonas acidovorans
of a Permease System Which Transports
l
-Tryptophan
Authors: Rosenfeld Henry , Feigelson Philip
Published: January 2020

Growth of
Pseudomonas acidovorans
in the presence of
l
-tryptophan resulted in the appearance of a tryptophan transport system which was extremely sensitive to sodium azide or 2,4-dinitrophenol. Asparagine-grown cells possessed no detectable tryptophan “permease” activity. Substitution of
l
-kynurenine for
l
-tryptophan in the growth medium also induced the tryptophan permease activity, along with tryptophan oxygenase and kynurenine formamidase. This is the first reported example of the product induction of a permease activity. Irrespective of whether
Pseudomonas
cells are grown in the presence of
d
- or
l
-tryptophan, the resulting induced tryptophan permease activity is specific for the
l
-isomer. In addition, the radioactive compounds
l
-leucine,
l
-phenylalanine, or
dl
-5-hydroxytryptophan are not transported. When
dl
-5-fluorotryptophan is a component of the inducing medium (with
l
-tryptophan), induction of tryptophan permease activity, as well as tryptophan oxygenase, is inhibited. In the permease assay system, using normally induced cells, the fluoroanalogue inhibited strikingly tryptophan transport. Therefore, this analogue may inhibit induction by blocking inducer transport into the cell. When added to the
l
-tryptophan-inducing medium,
dl
-7-azatryptophan markedly enhanced induction of tryptophan oxygenase, but the level of tryptophan permease activity was not further elevated. The mechanism of this analogue is unclear at present. Invariant tryptophan permease activity levels are found in cells grown with 5 or 15 m
m
l
-tryptophan or 5 m
m
l
-kynurenine, whereas the respective tryptophan oxygenase levels are greatly different. Together with other results, these results indicate that the synthesis of tryptophan permease activity is not coordinate with that of tryptophan oxygenase. Tryptophan transport is strongly inhibited by
l
-formylkynurenine and by
l
-kynurenine. These two metabolites were prepared in radioactive form, and they are actively transported following bacterial growth on
l
-tryptophan or
l
-kynurenine. Preliminary results suggest the tryptophan permease activity may be distinct from the permease(s) activity for
l
-formylkynurenine and
l
-kynurenine. Kynurenine, then, is capable of inducing tryptophan permease and kynurenine permease activities.
Role of Exogenous Adenosine Triphosphate in Catabolic and Synthetic Activities of
Chlamydia psittaci
Authors: Weiss Emilio , Wilson Noralee N.
Published: January 2020

The synthetic activities of isolated cells of the meningopneumonitis strain (MN) of
Chlamydia psittaci
were investigated and further observations were made on their catabolic reactions. These observations included the demonstration of CO
2
production from aspartate in the presence of pyruvate and the formation of pyruvate from glucose-6-phosphate. Both reactions were enhanced by added adenosine triphosphate (ATP). Of a large number of compounds tested, only glucose-6-phosphate, pyruvate, aspartate, and isoleucine were shown to furnish carbons that were incorporated into molecules precipitated by trichloroacetic acid. The reactions with pyruvate, aspartate, and isoleucine were dependent entirely, or almost entirely, on added ATP, and the reaction with glucose-6-phosphate was enhanced by ATP. Except for CO
2
, which greatly stimulated the reactions, the addition of a number of other compounds or a combination of compounds, such as cofactors, amino acids, and purine and pyrimidine bases, did not greatly affect incorporation. About 95% of the activity of the trichloroacetic acid precipitates was recovered in the chloroform-methanol soluble fraction.
Cytochrome and Ubiquinone Patterns During Growth of
Azotobacter vinelandii
Authors: Knowles Christopher J. , Redfearn Eric R.
Published: January 2020

After synthesis during the early log phase, the concentrations of ubiquinone and cytochromes did not vary during the growth cycle of
Azotobacter vinelandii
, when grown with either high or low aeration on nitrogen-free or urea-containing media. The level of aeration had no effect on the concentrations of the electron carriers synthesized, but affected the growth rate. On urea-containing medium, the concentration of cytochrome
a
2
was low, but it was synthesized at a linear rate when the bacteria were transferred to nitrogen-free medium.
A. vinelandii
was shown to utilize sufficient medium urea to account for all of the cell nitrogen. Growth on urea-containing medium with an oxygen atmosphere resulted in low growth yields, and cytochromes
c
4
+
c
5
were not synthesized; the concentrations of ubiquinone and cytochromes
b
1
,
a
1
, and
a
2
were only 12 to 18% of the values for growth on nitrogen-free medium with high aeration.
Relationships Between Bactericidal Effect and Inhibition of Ribonucleic Acid Nucleotidyl-transferase by Rifampicin in
Escherichia coli
K-12
Authors: Lancini Giancarlo , Pallanza Rosa , Silvestri Luigi G.
Published: January 2020

The mechanism of action of rifampicin, an antibiotic which inhibits in vitro the polycondensation of ribonucleotides by ribonucleic acid (RNA) nucleotidyltransferase, was studied in vivo in
Escherichia coli
. It is argued that the inhibition of RNA nucleotidyltransferase represents the primary lesion and is responsible for the bactericidal effect. This conclusion is based on (i) the correlation between concentrations of the antibiotic which block in vivo incorporation of labeled uracil and the bactericidal concentrations, (ii) the evidence that the loss of viability of the cells immediately follows the block of RNA synthesis, and (iii) the observation that the reversal of the inhibition of RNA synthesis goes together with a reversal of the loss of viability.
Relationships Between the Regulation of the Lactose and Galactose Operons of
Escherichia coli
Authors: Williams Beverly , Paigen Kenneth
Published: January 2020

A group of structurally related compounds, including galactose, fucose, and a number of galactosides, are regulatory effectors for both the
lac
and
gal
operons of
Escherichia coli
. Although a common set of effectors exists, each operon appears to be regulated independently of the other. Experiments with various regulatory mutants have shown, first, that the presence of the proteins of one operon is without effect on the regulation of the other and, second, that the influence an effector has on one operon is independent of the presence or the functional state of the regulatory genes of the other operon. It is unlikely, therefore, that the two operons share a common regulatory macromolecule. Both
gal R
−
and
gal o
c
regulatory mutants are equally resistant to repression by glucose and galactosides. It has been possible to show, in the
gal
operon, that induction and repression are competitive processes. For this operon, the differential rate of enzyme synthesis is set by the relative intracellular concentrations of inducer (fucose) and repressor (isopropylthiogalactoside).
Biochemical Basis of Obligate Autotrophy in
Nitrosomonas europaea
Authors: Hooper Alan B.
Published: January 2020

The specific activities of isocitric dehydrogenase, α-ketoglutaric dehydrogenase, succinic dehydrogenase, malic dehydrogenase, and reduced nicotinamide adenine dinucleotide (NADH) oxidase were determined in extracts of
Nitrosomonas europaea
and compared with the corresponding values for
Anacystis nidulans
and autotrophically grown
Hydrogenomonas eutropha
. In common with other obligate autotrophs and in contrast to facultative autotrophs,
Nitrosomonas
extracts lacked α-ketoglutaric dehydrogenase and KCN-sensitive NADH oxidase activity and had low succinic dehydrogenase activity. The
Nitrosomonas
NADH oxidase appeared to be of the peroxidase type.
Sugar Transport in
Mycoplasma gallisepticum
Authors: Rottem Shlomo , Razin Shmuel
Published: January 2020

Mycoplasma gallisepticum
cells were found to contain two different sugar transport systems, one for
d
-glucose and α-methyl-
d
-glucoside (α-MG) and the other for
d
-mannose and
d
-fructose. Both systems were noninducible, stereospecific, dependent on temperature and
p
H, and sensitive to sulfhydryl-blocking reagents. The rate of sugar uptake depended on its external concentration, obeying Michaelis-Menten kinetics. The sugar accumulated in the cells against a concentration gradient, and an energy requirement for accumulation was demonstrated with α-MG. Both transport systems thus meet the criteria of active transport. The exit of α-MG from the cells, like its entry, depended on temperature and was accelerated by energy supplied by the oxidizable
d
-mannose.
d
-Glucose accelerated α-MG exit, apparently by an exchange reaction. A method for measuring the intercellular space and intracellular free-water volume of
Mycoplasma
was devised, and several of its applications are described.
Conversion of Glucose-1-Phosphate to 3-Keto-glucose-1-phosphate by Cells of
Agrobacterium tumefaciens
Authors: Fukui Sakuzo
Published: January 2020

Incubation of resting cells of
Agrobacterium tumefaciens
with glucose-1-phosphate resulted in the accumulation of a new sugar phosphate in the suspending medium. Approximately 80% of the glucose-1-phosphate consumed was converted to the new compound, which was identified as α-
d
-
ribo
-hexopyranosyl-3-ulose-1-phosphate (3-ketoglucose-1-phosphate). Both utilization of glucose-1-phosphate and accumulation of 3-ketoglucose-1-phosphate were inhibited by 2,4-dinitrophenol, polymyxin, and
d
-glucose, which are inhibitors of the glucoside transport system of this bacterium but are not inhibitors of
d
-glucoside-3-dehydrogenase, which is the 3-ketoglucose-1-phosphate-forming enzyme. Consequently, it was concluded that glucose-1-phosphate penetrates into intracellular space by means of an active transport system. The glucose-1-phosphate is converted to 3-ketoglucose-1-phosphate by
d
-glucoside-3-dehydrogenase, and the 3-ketoglucose-1-phosphate formed reaches the extracellular space by passing through the surface layer of the bacterium.
Transitional Forms of
Corynebacterium acnes
in Disease
Authors: Zierdt C. H. , Wertlake P. T.
Published: January 2020

A clear-cut triad of sequential
Corynebacterium acnes
transitional forms from disease has been discovered. This entity includes three major forms which are capable of stabilization in culture, the spherical, the intermediate, and the definitive
C. acnes
. During conversion or reversion among the three forms, a variety of forms with mixed characteristics was observed. The spherical form was gram-negative and osmotically fragile, but it possessed a vestigial cell wall and mesosomes which excluded it from the L forms. In lieu of the L-form designation, the term “transitional” was adopted for all forms leading up to the definitive
C. acnes
. Culture of the spherical form was successful only on
Mycoplasma
-type media. The intermediate form was gram-negative, had mixed spherical and filamentous morphology, and bore a striking resemblance to
Streptobacillus moniliformis
. Like the spherical form, it was nutritionally exacting. The definitive form of
C. acnes
was preceded by gram-positive transitional forms of
C. acnes
morphology. It lacked, however, the carbohydrases and proteinases of
C. acnes
and susceptibility to
C. acnes
bacteriophages. Reversion was often blocked at this stage. A series of blood cultures from a patient with endocarditis was studied. Postmortem stain sections of the heart-valve lesion included intracellular masses of gram-negative spherical organisms. Indirect fluorescent antibody staining of these masses was strongly positive with antiserum to the spherical form and weakly positive with antiserum to the intermediate form.
Effect of Respiratory Inhibitors on the Motility of
Pseudomonas fluorescens
Authors: Faust M. A. , Doetsch R. N.
Published: January 2020

The translational motility of
Pseudomonas fluorescens
was weakly inhibited by oligomycin, Dicumarol, 2,4-dinitrophenol, 2
n
-heptyl-4-hydroxyquinoline
N
-oxide, and potassium cyanide. Atabrine and antimycin A together with potassium cyanide immediately immobilized this bacterium, but antimycin A alone was without effect. Gramicidin D also immobilized
P. fluorescens
, but its action was inhibited by K
+
and NH
4
+
ions. In like manner, the effect of
p
-chloromercuribenzoate could be counteracted with cysteine, thereby suggesting the involvement of —SH groups in flagellar motility processes. It appears that the energy required for motility of
P. fluorescens
is generated by oxidative phosphorylation mediated by the cytochrome system.
Characteristics of Penicillinase Secretion by Growing Cells and Protoplasts of
Bacillus licheniformis
Authors: Sargent M. G. , Ghosh B. K. , Lampen J. O.
Published: January 2020

Cultures of the inducible penicillinase-producing strain 749 of
Bacillus licheniformis
, induced with small amounts of benzylpenicillin, synthesized penicillinase at a high rate for a short period, after which the rate of synthesis slowly declined. During the period of active synthesis, the rate of secretion, as a fraction of the level of cell-bound penicillinase (which is originally high), gradually decreased to a constant level. Chloramphenicol, at a concentration (40 μg/ml) which completely inhibited synthesis of penicillinase, partially inhibited secretion if added during the period of active synthesis. During the phase of reduced synthesis, chloramphenicol was without effect on secretion. Penicillinase secretion, by actively growing cultures of the constitutive penicillinase-producing mutant 749/C, was inhibited by 75% immediately after addition of chloramphenicol. The secretion of part of the penicillinase released during active growth is probably dependent on synthesis of penicillinase, but part of the secreted penicillinase can be released in the absence of synthesis. Protoplasts were obtained from which periplasmic penicillinase has been removed, and these protoplasts were capable of substantial growth and penicillinase synthesis without lysis. At
p
H 7.5, there was no net incorporation of penicillinase into the cell membrane; the enzyme released was almost entirely of the exo form and was roughly equivalent to the amount of new enzyme formed. At
p
H 6.0, there was some incorporation of penicillinase into the plasma membrane, and approximately half of the extracellular penicillinase was in the exo form; the remainder perhaps represented membrane fragments. In the presence of chloramphenicol, a small amount of penicillinase was released at
p
H 7.5 as the exo form; at
p
H 6.0, practically none was released. We suggest that, with the removal from protoplasts of the periplasmic penicillinase-containing particles, a restriction on secretion has been lifted.
Control of Fatty Acid Metabolism I. Induction of the Enzymes of Fatty Acid Oxidation in
Escherichia coli
Authors: Weeks Gerald , Shapiro Martin , Burns R. O. , Wakil Salih J.
Published: January 2020

Escherichia coli
grows on long-chain fatty acids after a distinct lag phase. Cells, preadapted to palmitate, grow immediately on fatty acids, indicating that fatty acid oxidation in this bacterium is an inducible system. This hypothesis is supported by the fact that cells grown on palmitate oxidize fatty acids at rates 7 times faster than cells grown on amino acids and 60 times faster than cells grown on a combined medium of glucose and amino acids. The inhibitory effect of glucose may be explained in terms of catabolite repression. The activities of the five key enzymes of β-oxidation [palmityl-coenzyme A (CoA) synthetase, acyl-CoA dehydrogenase, enoyl-CoA hydrase, β-hydroxyacyl-CoA dehydrogenase, and thiolase] all vary coordinately over a wide range of activity, indicating that they are all under unit control. The ability of a fatty acid to induce the enzymes of β-oxidation and support-growth is a function of its chain length. Fatty acids of carbon chain lengths of C
14
and longer induce the enzymes of fatty acid oxidation and readily support growth, whereas decanoate and laurate do not induce the enzymes of fatty acid oxidation and only support limited growth of palmitate-induced cells. Two mutants, D-1 and D-3, which grow on decanoate and laurate were isolated and were found to contain constitutive levels of the β-oxidation enzymes. Short-chain fatty acids (<C
8
) do not support growth of either the parent strain or the mutants D-1 and D-3. Evidence is also presented to show that decanoate is actively transported by the parent strain and by the mutants.
Chromosome Replication in
Salmonella typhimurium
Authors: Chan Hilary , Lark Karl G.
Published: January 2020

The replication of the
Salmonella typhimurium
chromosome was studied. As with
E. coli
15T
−
, replication was sequential. After amino acid starvation, replication proceeded from a unique and heritable region of the chromosome. 5-Bromouracil, when substituted for thymine, did not disturb the sequence of replication nor did it initiate extra replication cycles. By labeling the origin and the terminus of the chromosome with
3
H- and
14
C-thymine, respectively, it was possible to determine that the rate of chain elongation decreases as the growth rate decreases. No gap in the replication cycle could be observed.
Structural Changes in
Stigmatella aurantiaca
During Myxospore Induction
Authors: Reichenbach Hans , Voelz Herbert , Dworkin Martin
Published: January 2020

Suspension cultures of
Stigmatella aurantiaca
(
Chondromyces aurantiacus
) were induced to form myxospores by addition of glycerol to the growing culture. The cells were fixed at various stages during conversion, thin sections were prepared, and changes in fine structure were studied. Vegetative cells are quite similar in their ultrastructure to
Myxococcus xanthus
. During transformation into myxospores, three important cytological changes were observed. Granules of storage material, probably polysaccharide and polyphosphate, accumulated; a 200 to 300-μm thick capsule was laid down, and the outer triple layer of the cell wall became locally folded. These cell wall folds were often densely packed and lay in pockets formed by the cytoplasmic membrane. We have suggested the possibility that the cell may store in these folds wall material which has become superfluous by the decrease in surface area during conversion.
Preparation of Cell Walls and Protoplasm of
Neisseria
with the Ribi Cell Fractionator
Authors: Martin John E. , Peacock William L. , Reising Gilbert , Kellogg Douglas S. , Ribi Edgar , Thayer James D.
Published: January 2020

The varied pressures required for disruption of
Neisseria gonorrhoeae
and other species of
Neisseria
when the Sorvall-Ribi refrigerated cell fractionator is used in the preparation of cell walls and cellular protoplasm are reported. Optimal disruption pressure for the gonococcus was considerably less than that required for other members of the genus
Neisseria
. Pressures varied from 8,000 psi for
N. gonorrhoeae
F62, colony type 4, to 22,000 psi for the nonpathogenic
Neisseria—N. sicca, N. flava
, and
N. catarrhalis
. Representative electron photomicrographs are shown.
Properties of Purified Staphylococcal β-Hemolysin
Authors: Gow John A. , Robinson John
Published: January 2020

Purification of β-hemolysin was achieved by ammonium sulfate precipitation, Sephadex G-100 gel filtration, carboxymethyl cellulose column chromatography, and density gradient electrophoresis. Active fractions eluted from carboxymethyl cellulose contained at least one nonhemolytic protein, and omission of this step was not detrimental to the purification process. Density gradient electrophoresis yielded approximately 1.6 mg of highly active purified β-hemolysin per liter of culture supernatant liquid. Purified β-hemolysin gave a single line on gel double diffusion and immunoelectrophoresis. A single symmetrical peak formed in the analytical ultracentrifuge, and the sedimentation coefficient was calculated to be 1.7
S
. The purified β-hemolysin was stable at 4 C and could be lyophilized. Magnesium cations were required for full expression of β-hemolytic activity. β-Hemolysin was lethal for rabbits when injected intravenously in amounts between 40 and 160 μg. Crude β-hemolysin was more stable than purified β-hemolysin when heated at 60 C for 30 min. Purified β-hemolysin lost almost all of its activity on subsequent heating at 100 C for 10 min.
Cell Wall Composition of the Yeast and Mycelial Forms of
Paracoccidioides brasiliensis
Authors: Kanetsuna Fuminori , Carbonell Luis M. , Moreno Ramon E. , Rodriguez Joaquin
Published: January 2020

Isolation and chemical analyses of the cell walls of the yeast (Y form) and mycelial forms (M form) of
Paracoccidioides brasiliensis
and
Blastomyces dermatitidis
revealed that their chemical composition is similar and depends on the form. Lipids, chitin, glucans, and proteins are the main constituents of the cell walls of both forms of these fungi. There is no significant difference in the amount of lipids (5 to 10%) and glucans (36 to 47%) contained by the two forms. In both fungi, the Y form has a larger amount of chitin (37 to 48%) than the M form (7 to 18%), whereas the M form has a larger amount of proteins (24 to 41%) than the Y form (7 to 14%). Several properties of the glucan of
P. brasiliensis
were studied. Almost all of the glucan in the Y form was soluble in 1
n
NaOH, was weakly positive in the periodic acid-Schiff reaction, was not hydrolyzed by snail digestive juice, and had α-glycosidic linkage. Glucans of the M form were divided into alkali-soluble (60 to 65%) and alkali-insoluble (35 to 40%) types. The alkali-soluble glucan was similar to that of the Y form; the alkali-insoluble glucan was positive in the periodic acid-Schiff reaction and was hydrolyzed by snail digestive juice.
Alteration of Physical, Chemical, and Biological Properties of Endotoxin by Treatment with Mild Alkali
Authors: Niwa M. , Milner K. C. , Ribi E. , Rudbach J. A.
Published: January 2020

Treatment with alkali is one of several methods for removing fatty acids from bacterial endotoxins and, in the process, detoxifying the material. Saponification of fatty acid esters is the major detectable chemical change produced by alkali; however, kinetic studies of mild alkaline hydrolysis of endotoxin failed to correlate rates of detoxification with rates of loss of ketodeoxyoctonates, heptose, O-acetyl groups, or fatty acid esters. The alterations occurring during the critical stages of hydrolysis apparently changed the essential chemical conformation of endotoxic particles before cleavage of a significant amount of material took place. The rates of both saponification and detoxification were markedly increased by carrying out the reaction in media of ethyl alcohol or dimethylsulfoxide instead of water.
Serological Properties of Lipopolysaccharide from Oral Strains of
Bacteroides melaninogenicus
Authors: Hofstad Tor
Published: January 2020

Lipopolysaccharide (LPS) extracted with phenol-water from four oral strains of
Bacteroides melaninogenicus
was found to be serologically active in precipitation and complement fixation tests and sensitized sheep erythrocytes to agglutination. Except for the capacity to inhibit indirect hemagglutination, the serological activity was destroyed by oxidation with periodate. The isolated LPS was antigenic in rabbits, giving rise to low- and high-molecular-weight antibodies. Cross-reactivity experiments revealed the presence in LPS of both type-specific and group-reactive antigenic determinants.
Inhibition of the Peptide Bond Synthesizing Cycle by Chloramphenicol
Authors: Weber Michael J. , DeMoss J. A.
Published: January 2020

To study the mechanism by which chloramphenicol inhibits bacterial protein synthesis, we examined the kinetics of the puromycin-induced release of peptides from transfer ribonucleic acid (tRNA) in the presence and in the absence of chloramphenicol. Washed
Escherichia coli
ribosomes with nascent peptides which had been radioactively labeled in vivo were used for this study. When such ribosomes were incubated in the presence of 10 μg of puromycin per ml, approximately one-fourth of the radioactive peptide material was rapidly released from tRNA. This rapid, puromycin-dependent reaction is assumed to be equivalent to the peptidyl transferase reaction. Chloramphenicol inhibited the extent of the puromycin-induced release of peptides by only 50%, demonstrating that some of the peptide chains which are present on active ribosomes react with puromycin, even in the presence of chloramphenicol. The addition of the supernatant fraction and guanosine triphosphate (GTP) increased the extent of the puromycin-induced release; this additional release was completely inhibited by chloramphenicol. Peptidyl chains on washed ribosomes prepared from chloramphenicol-inhibited cells were not released by puromycin in the presence of chloramphenicol and reacted slowly with puromycin in the absence of chloramphenicol. The release of peptidyl groups from these ribosomes became largely insensitive to chloramphenicol after preincubation of the ribosomes with GTP and the supernatant fraction. We conclude that chloramphenicol does not inhibit the peptidyl transferase reaction as measured by the puromycin-induced release of peptides from tRNA, but rather inhibits some step in the peptide synthesis cycle prior to this reaction.
Interaction Between Analogue Resistance and Amino Acid Auxotrophy in
Neurospora
Authors: Kinsey John A. , Stadler David R.
Published: January 2020

A new
p
-fluorophenylalanine resistant mutant of
Neurospora
(
fpr-1
) was isolated. It is unaffected by the suppressor of a previously described resistance mutant,
mtr
. The
fpr-1
locus is on linkage group V, tightly linked to
act-2
. The expression of resistance to
p
-fluorophenylalanine by
fpr-1
can be suppressed by genes controlling a requirement for lysine or arginine. The suppression seems to involve an increased sensitivity of the lysine and arginine auxotrophs to
p
-fluorophenylalanine.
Role of Glycols and Tweens in the Production of Ergot Alkaloids by
Claviceps paspali
Authors: Mizrahi A. , Miller G.
Published: January 2020

Several glycols and Tweens markedly stimulated the production of ergot alkaloids in submerged cultures of
Claviceps paspali
. The role of these compounds was investigated in shake flasks and bench-scale fermentors. 2,3-Butanediol was not utilized by the fungus, and
1,2
-propanediol-
1
-
14
C
was not incorporated into the alkaloids. Glycols and Tweens lowered the surface tension of the basal medium and promoted the utilization of metabolites. In the presence of glycols and Tweens, an increased uptake of labeled sorbitol and succinic acid took place, whereas the specific radioactivity of the alkaloids was not affected. These results indicated that glycols and Tweens are not involved directly in the biosynthetic process; they apparently acted as surface-active agents, facilitating transport of metabolites into the cells.
Serine Transhydroxymethylase in Methionine Biosynthesis in
Saccharomyces cerevisiae
Authors: Botsford J. L. , Parks L. W.
Published: January 2020

Serine transhydroxymethylase appears to be the first enzyme in the synthesis of the methyl group of methionine. Properties of serine transhydroxymethylase activity as assayed by the production of formaldehyde were correlated with properties of cell-free extracts for the methylation of homocysteine deriving the methyl group from the β-carbon of serine. The reaction required pyridoxal phosphate and tetrahydrofolic acid, and was characterized in cell-free extracts with respect to Michaelis constant,
p
H optimum, incubation time, and optimal enzyme concentration. The activity was sensitive to inhibition by methionine, and to a much greater extent by
S
-adenosylmethionine. Serine transhydroxymethylase and the methylation of homocysteine reactions were not repressed by methionine and were stimulated by glycine. The activities of cell-free extracts for these reactions were significantly higher in cells in exponential than in stationary growth. When cells were grown in 10 m
m
glycine, the activities remained high throughout the culture cycle. The data indicated that glycine rather than methionine is involved in the control of the formation of the enzyme.
Glucose Catabolism in
Rhizobium japonicum
Authors: Keele Bernard B. , Hamilton Pat B. , Elkan Gerald H.
Published: January 2020

Glucose catabolism in
Rhizobium japonicum
ATCC 10324 was investigated by the radiorespirometric method and by assaying for key enzymes of the major energy-yielding pathways. Specifically labeled glucose gave the following results for resting cells, with values expressed as per cent
14
CO
2
evolution: C-1=59%, C-2=51%, C-3=45%, C-4=59%, and C-6=43%. These values indicate that glucose was degraded by the Entner-Doudoroff pathway alone. Cells which grew in glucose-yeast extract-salts medium gave essentially the same pattern except for retardation of the C-6 carbon. The rates were: C-1=54%, C-2=42%, C-3=51%, C-4=59%, and C-6=32%. Hexokinase, glucose-6-phosphate dehydrogenase, transketolase, and an enzyme system which produces pyruvate from 6-phosphogluconate were found to be present in these cells. No 6-phosphogluconate dehydrogenase was detected. Oxidation of specifically labeled pyruvate gave the following
14
CO
2
evolution pattern: C-1=78%, C-2=48%, and C-3=37%; the pattern from acetate was C-1=73%; and C-2=56%. Oxidation of glutamate showed the preferential rate of
14
CO
2
evolution to be C-1 > C-2=C-5 > C-3, 4, whereas a higher yield of
14
CO
2
was obtained from the C-1 and C-4 carbons of succinate than from the C-2 and C-3 carbons. These data are consistent with the operation of the Entner-Doudoroff pathway and tricarboxylic acid cycle as the catabolic pathways of glucose oxidation in
R. japonicum
.
Influence of Side-Chain Substituents on the Position of Cleavage of the Benzene Ring by
Pseudomonas fluorescens
Authors: Seidman M. M. , Toms Anne , Wood J. M.
Published: January 2020

Pseudomonas fluorescens
was grown on mineral salts media with phenol,
p
-hydroxybenzoic acid,
p
-hydroxy-phenylacetic acid, or
p
-hydroxy-
trans
-cinnamic acid as sole carbon and energy source. Each compound was first hydroxylated,
ortho
to the hydroxyl group on the benzene ring, to give catechol, protocatechuic acid (3,4-dihydroxy-benzoic acid), homoprotocatechuic acid (3,4-dihydroxy-phenylacetic acid), and caffeic acid (3,4-dihydroxy-
trans
-cinnamic acid), respectively, as the ultimate aromatic products before cleavage of the benzene nucleus. Protocatechuic acid and caffeic acid were shown to be cleaved by
ortho
fission, via a 3,4-oxygenase mechanism, to give β-substituted
cis, cis
-muconic acids as the initial aliphatic products. However, catechol and homoprotocatechuic acid were cleaved by
meta
fission, by 2,3-and 4,5-oxygenases, respectively, to give α-hydroxy-muconic semialdehyde and α-hydroxy-γ-carboxymethyl muconic semialdehyde as initial aliphatic intermediates. Caffeic acid: 3,4-oxygenase, a new oxygenase, consumes 1 mole of O
2
per mole of substrate and has an optimal
p
H of 7.0. The mechanism of cleavage of enzymes derepressed for substituted catechols by
P. fluorescens
apparently changes from
ortho
to
meta
with the increasing nephelauxetic (electron donor) effect of the side-chain substituent.
Staphylococcal Acid Phosphatase: Extensive Purification and Characterization of the Loosely Bound Enzyme
Authors: Malveaux F. J. , Clemente C. L. San
Published: January 2020

Acid phosphatase of
Staphylococcus aureus
PS55 was eluted from the surface of these cells with 1.0
m
KCl at
p
H 8.5 by gentle agitation at 25 C and was purified 44-fold (51% recovery) by two cycles of dialysis and gel filtration. The eluted enzyme which had a 280/260 (nm) absorbancy ratio of 0.71 required at least 0.5
m
salt solution for solubilization; however, most of the purified product which had a 280/260 (nm) absorbancy ratio of 1.72 was soluble in dilute buffer solution [0.01
m
tris(hydroxymethyl)aminomethane chloride,
p
H 8.5]. Purified acid phosphatase appeared homogeneous according to the criteria of gel filtration, starch-block electrophoresis, and analytical ultracentrifugation. In a starch block, migration was toward the cathode at
p
H 8.0. Maximal activity occurred at
p
H 5.2 to 5.3 and salt concentration had little effect on phosphatase activity up to 1.0
m
KCl or NaCl. Progressive loss of enzymatic acitivity occurred at higher salt concentrations. Molecular weight of purified acid phosphatase was estimated to be 58,000.
Isoleucine Biosynthesis from 2-Methylbutyric Acid by Anaerobic Bacteria from the Rumen
Authors: Robinson Isadore M. , Allison Milton J.
Published: January 2020

Microorganisms in ruminal ingesta and pure cultures of anaerobic ruminal bacteria of different physiological and morphological groups incorporated
14
C from labeled 2-methylbutyrate during growth. The radioactivity was incorporated mainly into lipid and protein. Isoleucine was the only labeled amino acid found in acid hydrolysates of protein from either pure or mixed cultures. Radioactivity in isoleucine synthesized from 2-methylbutyrate-
1
-
14
C
was entirely in carbon-2. Thus, the carboxylation of 2-methylbutyrate is a pathway for synthesis of isoleucine different from that operative in many aerobic and facultative microorganisms. The specific activity of isoleucine from 2-methylbutyrate by
Bacteroides rumminicola
23 increased with higher concentrations of 2-methylbutyrate (2.6 to 44 × 10
−5
m
) in the growth medium. At the highest concentration, the specific activity of isoleucine synthesized was 40% of the specific activity of the 2-methylbutyrate in the growth medium. The use of enzymatic casein hydrolysate, oxytocin, or vasopressin rather than ammonia as nitrogen source for growth of strain 23 depressed the incorporation of 2-methylbutyrate into isoleucine. Synthesis of isoleucine from 2-methylbutyrate appears to be an important reaction in the rumen.
Repression of the Histidine Operon: Effect of the First Enzyme on the Kinetics of Repression
Authors: Kovach John S. , Berberich M. A. , Venetianer Pál , Goldberger Robert F.
Published: January 2020

Kinetic studies on repression of the enzymes for histidine biosynthesis in
Salmonella typhimurium
showed that, upon addition of histidine to a derepressed culture, the enzymes became repressed in a temporal sequence which corresponds with the positional sequence of the genes in the histidine operon. This serial pattern of repression occurred under conditions in which the feedback site of the first enzyme for histidine biosynthesis is intact. When this site was rendered nonfunctional the pattern of repression was changed so that all of the enzymes became repressed concomitantly. These results suggest that the first enzyme for histidine biosynthesis plays a hitherto unrecognized role in control of the histidine system.
Nitrate Reductase Complex of
Escherichia coli
K-12: Isolation and Characterization of Mutants Unable to Reduce Nitrate
Authors: Ruiz-Herrera José , Showe Michael K. , DeMoss J. A.
Published: January 2020

Thirty-eight mutants unable to reduce nitrate were isolated from
Escherichia coli
and characterized biochemically and genetically. All of the mutants exhibited reduced or insignificant levels of formate dehydrogenase, nitrate reductase, or various combinations of these activities and cytochrome
b
1
under conditions which resulted in the production of high levels of these activities by the wild-type parental strains. Most of the mutants reverted readily to wild type, and all mapped within a restricted region on the chromosome linked to the tryptophan genes. It was proposed that nitrate reduction in
E. coli
was catalyzed exclusively by an organized complex containing formate dehydrogenase, cytochrome
b
1
, and nitrate reductase.