bluuebunny/crossref_metadata_2025 huggingface dataset:
Mutant Strains of
Escherichia coli
K-12 Unable to Form Ubiquinone
Authors: Cox G. B. , Gibson F. , Pittard James
Published: January 2020

A strain of
Escherichia coli
was isolated which was unable to form ubiquinone. This mutant was obtained by selecting strains unable to grow on malate as sole source of carbon. Such strains were further screened by examination of the quinone content of cells grown on a glucose medium. A mutant unable to form vitamin K was also isolated by this procedure. A genetic analysis of the ubiquinoneless strain showed that it possessed two mutations affecting ubiquinone biosynthesis.
Cytochromes of Aquatic Fungi
Authors: Gleason Frank H. , Unestam Torgny
Published: January 2020

The cytochrome systems of two classes of aquatic fungi, the
Oomycetes
and
Chytridiomycetes
, were studied by means of reduced-minus-oxidized difference spectra at room and at low temperature. At room temperature, all of these fungi have a
c
-type cytochrome with an absorption maximum at 551 mμ and a
b
-type cytochrome at 564 mμ. The
Oomycetes
have
a
-type cytochromes at 605 mμ, and the
Chytridiomycetes
have
a
-type cytochromes at 606 mμ (
Blastocladiales
) or at 609 mμ (
Monoblepharidales
). Additional
b
-type cytochromes are found at 557 mμ in the
Oomycetes
and at approximately 560 mμ in the
Chytridiomycetes
. The data obtained from spectra at low temperature are consistent with these conclusions. Thus, the difference spectra reveal variation between the cytochrome systems of these two classes of aquatic fungi.
Effects of Three Bacterial Infections on Serum Lipids of Rabbits
Authors: Farshtchi Davood , Lewis Vester J.
Published: January 2020

Alteration of the rabbit serum lipids as a result of three bacterial infections was studied by quantitative thin-layer and gas-liquid chromatography. Anthrax infection slightly changed the serum lipid. Cholesterol did not change, though free fatty acids, triglycerides, and cholesteryl esters doubled, and lecithin increased threefold. Tularemia infection produced drastic changes in the serum lipid content of rabbits, increasing levels of cholesterol over 4-fold, free fatty acids 17-fold, triglycerides 11-fold, cholesteryl esters 2.5-fold, and lecithin almost 3-fold. Pneumococcus infection increased cholesterol 2.5 times, free fatty acids were more than doubled, triglycerides were increased 9.5 times, and lecithin was increased almost 4 times. Gas-liquid chromatographic analysis of the methyl esters of free fatty acids showed only quantitative changes in these acids due to infection. Some possible mechanisms of alteration of serum lipid content are discussed.
Chromosome Mapping in
Staphylococcus aureus
Authors: Altenbern Robert A.
Published: January 2020

The genome of
Staphylococcus aureus
was mapped by enumerating mutants induced by nitrosoguanidine during synchronous chromosomal replication following release from phenethanol inhibition. Both chromosomal replication time and cell division time were 120 min for this strain of
S. aureus
. Duplication of genes occurred within a 10-min period of the 120 min required for chromosomal replication. A high-resolution method was devised to determine the gene order of four genes that duplicated in the same 10-min interval of replication of the chromosome. A genomic map locating the positions of 10 genes was derived.
Sensitivity of Rough Gram-negative Bacteria to the Bactericidal Action of Serum
Authors: Rowley D.
Published: January 2020

Three
Salmonella minnesota
rough mutants were found to be more sensitive to the bactericidal action of antibody and complement than was the parent smooth strain. The antibodies involved were shown to be against components which are all present in the smooth parent strain and are not identical with the lipopolysaccharides isolated by the phenol-water extraction procedure. The lipopolysaccharide of the smooth strain was shown to confer resistance by blocking access of antibody to the sensitive antigens.
Nitrite Formation from Hydroxylamine and Oximes by
Pseudomonas aeruginosa
Authors: Amarger Noelle , Alexander M.
Published: January 2020

Nitrite was formed from hydroxylamine and several oximes by intact cells and extracts of
Pseudomonas aeruginosa
. The activity was induced by the presence of oximes in the culture medium. Nitroalkanes were not intermediates in the conversion of acetaldoxime, acetone oxime, or butanone oxime to nitrite, since nitromethane inhibited the formation of nitrite from the nitro compounds but not from the corresponding oximes. The oxime apparently functions as a constant source of hydroxylamine during growth of the bacterium. Hydroxylamine at low concentration was converted stoichiometrically to nitrite by extracts of the bacterium; high concentrations were inhibitory. Nicotinamide adenine dinucleotide phosphate, oxygen, and other unidentified cofactors were necessary for the reaction. Actively nitrifying extracts possessed no hydroxylamine-cytochrome
c
reductase activity. Hyponitrite, nitrous oxide, and nitric oxide were not metabolized.
Isoleucine and Valine Metabolism of
Escherichia coli
XV. Biochemical Properties of Mutants Resistant to Thiaisoleucine
Authors: Szentirmai A. , Szentirmai M. , Umbarger H. E.
Published: January 2020

Thiaisoleucine-resistant mutants of
Escherichia coli
strain K-12 which exhibited reduced isoleucyl soluble ribonucleic acid synthetase activity were isolated. Resistance was apparently achieved by the selection of a synthetase with a 10-fold decrease in apparent affinity for thiaisoleucine. This mutation also resulted in a 2.5-fold decrease in apparent affinity for the natural substrate,
l
-isoleucine, and less activity than found in wild type. The mutants grew more slowly than wild type and were derepressed for three of the five enzymes in the pathways to isoleucine and valine.
Isoleucine and Valine Metabolism of
Escherichia coli
XVI. Pattern of Multivalent Repression in Strain K-12
Authors: Dwyer Susan B. , Umbarger H. E.
Published: January 2020

The levels of the five enzymes required for isoleucine and valine synthesis were examined under several growth conditions in strain K-12 of
Escherichia coli
and mutants derived from it. In strains with wild type repressibility, the same pattern of derepression was found on limiting isoleucine as is found to be constitutive in strain Tir-8, which has an altered isoleucine-activating enzyme. Homoserine dehydrogenase, which is essential for the biosynthesis of threonine and is normally derepressed on limiting isoleucine or threonine, is also derepressed in strain Tir-8. Threonine deaminase and homoserine dehydrogenase were partially repressed in strain Tir-8 by very high levels of isoleucine, but were not further derepressed over levels in minimal medium by limiting isoleucine.
Amino Acid Transport in
Mycoplasma
Authors: Razin S. , Gottfried Lily , Rottem S.
Published: January 2020

The uptake of
l
-histidine by
Mycoplasma fermentans
and
l
-methionine by
M. hominis
was found to be dependent on temperature and
p
H and to follow saturation kinetics. Several metabolic inhibitors inhibited this uptake. The transport system for
l
-methionine was highly specific. The
l
-histidine transport system was less specific, and the uptake was competitively inhibited by
l
-arginine and
l
-lysine.
l
-Histidine accumulated in the intracellular pool of
M. fermentans
at a concentration about 200 times that found in the medium. Efflux of accumulated
l
-histidine was demonstrated at 37 C, but not at 0 C. The rate of efflux was greatly accelerated by addition of
l
-histidine to the medium. The findings indicate that the
Mycoplasma
cell membrane contains specific transport systems resembling the permease systems of other microorganisms.
Galactose Transport in
Saccharomyces cerevisiae
I. Nonmetabolized Sugars as Substrates and Inducers of the Galactose Transport System
Authors: Cirillo Vincent P.
Published: January 2020

The inducible galactose transport system in bakers' yeast carries out the facilitated diffusion of the nonmetabolized galactose analogues
d
-fucose and
l
-arabinose. This capacity depends on the activity of the Ga 2 gene. In some strains,
d
-fucose and
l
-arabinose are also gratuitous inducers. Mutants in which the inducibility of the galactose pathway enzymes is altered show a parallel alteration of the inducibility of the galactose transport system.
Viability in Fertile Stocks of
Pseudomonas aeruginosa
Authors: Herman Alberta I. , Griffin Patricia S.
Published: January 2020

Diluent composition, time consumed in experimental manipulations, and the presence of pyocine-like lethal agents affected the viability of sexual fertility factor-positive and fertility factor-negative auxotrophic stocks of
Pseudomonas aeruginosa
. In the same cultures, recovery of prototrophic revertants increased as the number of viable cells dispensed per plate was reduced. As a result, the number of revertants recovered was indirectly determined by the combined activities of the three conditions affecting viability. Possible modifications by these conditions affecting viability on the expression and interpretation of the fertility factor-positive sex factor-mediated system of genetic recombination are presented.
Drug Resistance of Staphylococci VII. Genetic Determinants Responsible for the Resistance to Tetracycline, Streptomycin, Sulfanilamide, and Penicillin
Authors: Kasuga Tokuhiko , Hashimoto Hajime , Mitsuhashi Susumu
Published: January 2020

A genetic analysis of resistance to tetracycline (TC), streptomycin (SM), sulfanilamide (SA), and penicillin G was carried out through transduction with phage lysates obtained from a multiply resistant strain of
Staphylococcus aureus
by ultraviolet irradiation. All transductants acquired resistance to both TC and SA, even when singly selected for either SA or TC resistance. The locus responsible for TC resistance could not be separated genetically from that for SA resistance. On the other hand, in transduction of SM resistance, about 30% of the transductants jointly acquired resistance to both TC and SA. These observations suggest that the loci governing resistance to TC, SA, and SM exist close together on a single genetic unit, this probably being the chromosome.
Anti-Pasteurella pestisFactor III. Effects of Fatty Acids onPasteurella pestis
Authors: Eisler D. M. , von Metz E. K.
Published: January 2020

The bactericidal activity and the chemical and physical characteristics of lipid fractions of extracts from organs of normal mice and guinea pigs have been described previously. The present study describes the effects of commercially prepared fatty acids which are representative of those found in the extracts. Saturated fatty acids with 12, 14, and 16 carbon atoms and unsaturated fatty acids with more than one double bond were the most effective in killingPasteurella pestis. Tweens 20 and 80, Spans 40 and 80, and some of the methyl esters of the fatty acids did not strongly inhibitP. pestis. It was concluded, therefore, that both the length of the carbon chain and the presence of the carboxyl group of the free fatty acids were important in their effects onP. pestis. Neither the very active lauric acid nor the relatively inactive oleic acid appeared to severely alter the morphology ofP. pestis. Supernatant fluids from incubated mixtures of sodium laurate or sodium oleate and cells did not contain significantly greater concentrations of proteins or nucleic acids than did the controls. These observations do not preclude an alteration of the permeability of the cell walls.
Identification of Propionate as an Endogenous CO
2
Acceptor in
Rhodospirillum rubrum
and Properties of Purified Propionyl-Coenzyme A Carboxylase
Authors: Olsen I. , Merrick J. M.
Published: January 2020

A heat-stable endogenous CO
2
acceptor has been found in extracts of
Rhodospirillum rubrum
grown photoheterotrophically on acetate. Evidence is presented which suggests that this factor is propionic acid. Thus, paper and gas chromatographic analyses have indicated that propionic acid is present in boiled extracts prepared from
R. rubrum
cells. The products of
14
CO
2
fixation obtained with either the boiled extract or propionic acid as the CO
2
acceptor were identical and were identified as methylmalonic acid and succinic acid by paper chromatography. The enzyme which catalyzes the carboxylation of propionyl-coenzyme A (propionyl-CoA carboxylase) was purified from
R. rubrum
cells grown on acetate and its properties were studied. The enzyme is similar to propionyl-CoA carboxylases isolated from mammalian sources.
Cytochrome
c
Oxidation by the Electron Transport Fraction of
Azotobacter vinelandii
Authors: Jurtshuk Peter , Old Lynn
Published: January 2020

The spectrophotometric oxidation of horse heart ferrocytochrome
c
was examined by use of the particulate electron transport fraction (R
3
) of
Azotobacter vinelandii
strain O. Unlike cytochrome
c
, purified preparations of native
Azotobacter
cytochromes
c
4
+
c
5
were oxidized only slowly by the electron transport fraction. The oxidation of mammalian cytochrome
c
proceeded at an appreciable rate and displayed “apparent” first-order kinetics at a
p
H optimum of 9.0 with tris(hydroxymethyl)aminomethane-chloride buffer. The calculated
V
max
value was 0.22 μmole of cytochrome
c
oxidized per min per mg of protein (25 C) and a
K
m
value for cytochrome
c
of 2.3 × 10
−5
m
was obtained. Ferricytochrome
c
was a “strict” competitive inhibitor for this oxidation. Cytochrome
c
oxidation by the
Azotobacter
electron transport system was markedly sensitive to cyanide, azide, and hydroxylamine, although carbon monoxide inhibition could not be demonstrated. It was sensitive also to high concentrations of phosphate, ethylenediaminetetraacetate, and some metal cations. “Aging” or prolonged storage of the
Azotobacter
R
3
fraction, at 4 C for 10 days, resulted in a threefold increase in specific activity. The cytochrome
c
peroxidase type of reaction did not occur with the R
3
electron transport fraction.
Peptidoglycan of a Chemolithotrophic Bacterium,
Ferrobacillus ferrooxidans
Authors: Wang W. S. , Lundgren D. G.
Published: January 2020

The rigid layer (peptidoglycan) of the wall of the chemolithotroph
Ferrobacillus ferrooxidans
was isolated after various chemical treatments. The removal of specific components was followed by noting in an electron microscope changes in the appearance of the cell surface. The final peptidoglycan was virtually free from proteins and was sensitive to the action of lysozyme. Results of chemical analyses of acidhydrolyzed peptidoglycan revealed three major amino acids and two amino sugars: glutamic acid, α,ε-diaminopimelic acid, alanine, glucosamine, and muramic acid in a ratio of 1:1:2.33:062:088.
Alterations in the Morphology ofBacillus subtilisAfter Exposure to β-Lysin and Ultraviolet Light
Authors: Matheson Audria , Donaldson David M.
Published: January 2020

Viable counts, turbidities, and electron micrographs ofBacillus subtilisexposed to β-lysin and ultraviolet light (UV), singly or in combination, were compared in an attempt to relate death with changes in morphology. The decreases in survival of both the β-lysin- and UV-treated cells were rapid and preceded decreases in turbidity, as well as the changes in morphology. No significant differences were observed in turbidity reduction or morphological alterations of control cells from those of cells exposed to UV light. These cells developed prominent subcell wall spaces during incubation in the hypertonic stabilizing medium. No observable damage in either the cell wall or the cell membrane had taken place during 4 hr, but by 20 hr extensive damage of these two structures was apparent. The control and UV-treated cells exposed to β-lysin did not develop prominent subcell wall spaces. Within 2 hr, lesions were observable in their cell walls, and the cytoplasmic membranes were permeable to phosphotungstic acid. The damage to these structures became more extensive with time. Although the visible changes of control and UV-treated cells were evident much later than those induced by β-lysin, the morphological alterations in all cells were similar. It appeared that β-lysin caused an accelerated release of an autolytic enzyme which digested the cell walls.
Prosthecomicrobium
and
Ancalomicrobium
: New Prosthecate Freshwater Bacteria
Authors: Staley James T.
Published: January 2020

Direct microscopic examination of natural freshwater samples reveals a variety of small microorganisms having elaborate cellular appendages. Several strains have been isolated from crude cultures containing low concentrations of organic nutrients. All of the isolates are procaryotic. They are aerobic chemoorganotrophs that require vitamins for growth. Because they cannot be assigned to any of the existing bacterial genera, two new genera are proposed:
Ancalomicrobium
for organisms which have several long appendages and which reproduce by budding;
Prosthecomicrobium
for organisms which have many short appendages tapering toward a blunt tip and which reproduce by binary fission. Gas vacuoles have been found in strains of each genus. The term
prostheca
is proposed for the rigid appendages of procaryotic cells bounded by the cell wall, and is defined to include the structures on these new bacteria, as well as the stalks of the caulobacters and the hyphae of the hyphomicrobia.
Fluorescent-Antibody Approach to Study of Rhizobia in Soil
Authors: Schmidt E. L. , Bankole R. O. , Bohlool B. B.
Published: January 2020

Application of fluorescent-antibody (FA) techniques to the study of rhizobia as free-living soil bacteria was explored. Antiserum to a particular strain of
Rhizobium japonicum
proved specific in both agglutination and FA tests. Within the
R. japonicum
group, 2 of 12 strains were stained by the conjugate and these fluoresced brightly; all others were entirely negative. FA tests were negative for 7 strains of
R. meliloti
, 9 strains of
R. leguminosarum
, 9 strains of
R. trifolii
, 6 strains of
R. phaseoli
, and 65 unidentified bacteria isolated from 12 soils.
R. japonicum
grew in autoclaved soil and was readily detectable by FA examination of contact slides. The FA technique also detected antibody-reacting bacteria in a field soil whose rhizobial content was unknown. Fluorescent cells were probably
R. japonicum
, since nodules developed on soybean plants grown in the same soil sample and FA preparations of the crushed nodules proved positive. Autofluorescence was not a problem, but nonspecific adsorption of conjugate restricted observations to microscopic fields free from soil particles. Nonspecific adsorption was substantial, irrespective of the soil used.
Carbohydrate Composition of the Phenol-soluble Lipopolysaccharides of
Citrobacter freundii
Authors: Raff Rudolf A. , Wheat R. W.
Published: January 2020

Phenol-soluble lipopolysaccharides were obtained from the interphase and phenol phase fractions of 44% aqueous phenol-extracted
Citrobacter
species. Upon detailed investigation of
C. freundii
8090, the two lipopolysaccharide fractions were found to contain different amounts of lipid A, although qualitative composition was similar. Both contained lipid A, 2-keto-deoxyoctonic acid, heptose, phosphate,
d
-glucose, galactose, rhamnose, 2-acetamido-2 deoxy-
d
-glucose, 3-acetamido-3,6-dideoxy-
d
-glucose,
O
-acetyl, and trace amino acids. Partially purified phenol-phase lipopolysaccharide partitioned into the phenol-soluble phase when refractionated with 44% aqueous phenol, and was further found to be soluble in 88% phenol, 95% ethyl alcohol, and chloroform-methanol (2:1).
Oxidation of Phenolic Compounds by
Mycobacterium leprae
and Inhibition of Phenolase by Substrate Analogues and Copper Chelators
Authors: Prabhakaran Kochukunju , Kirchheimer Waldemar F. , Harris Eugene B.
Published: January 2020

Experiments were conducted on the substrate specificity of phenoloxidase in
Mycobacterium leprae
, by using various phenolic compounds. Comparative studies were carried out with the enzyme from mammalian and plant sources. The phenolase of
M. leprae
was found to be similar to the enzyme of plant origin in oxidizing a variety of substrates; it was different from the mammalian enzyme, which has a limited substrate specificity. The findings confirmed that phenoloxidase is a specific property of
M. leprae
and is not a result of adsorption of host-tissue enzymes. The method used in separation of bacilli from infected tissues was evaluated for its effect on the viability of the organisms. This was tested by using
M. lepraemurium
as a model. The preparative procedure was found to have no adverse effect on the ability of the organisms to multiply in the mouse foot-pad. Several inhibitors of phenoloxidase have been tested—both substrate analogues and compounds which bind copper in the enzyme. Substances binding copper were found to be more effective. Since phenolase has been found to be a characteristic metabolic activity in
M. leprae
, nontoxic inhibitors of the enzyme offer possibilities of developing a rational chemotherapy of leprosy.
Experimental Infection with Parent and L-Phase Variants of
Neisseria meningitidis
Authors: Bohnhoff Marjorie , Page Malcolm I.
Published: January 2020

Thirty-six strains of
Neisseria meningitidis
, including groups A, B, and C, produced L forms in vitro in the presence of an osmotic stabilizer and high concentrations of horse serum using penicillin as the transforming agent. Transformation to L growth occurred most readily among strains recently isolated from patients, and an unusually high rate of transformation was observed in 7 of the 36 strains. Revertant L strains developed diplococcal colonies on blood-agar and L colonies on sucrose-serum-penicillin-agar—always in a ratio of approximately 10 to 100 diplococcal colonies to 1 L colony. Using mucin as a host depressant, comparison was made between parent and revertant L strains of their initial pathogenicity and development of virulence by serial mouse passage. In general, revertant L strains showed the same pathogenic characteristics as the parent. Heart blood cultures from mice dying of infection with revertant L strains retained their ability to grow as L forms on penicillin media. Three stable L strains were completely avirulent for mice, although persistence of L forms could be demonstrated in peritoneal exudate for 6 days after inoculation.
Methylation of the Cellular Lipid of Methionine-requiringAgrobacterium tumefaciens
Authors: Kaneshiro Tsuneo
Published: January 2020

Mutants ofAgrobacterium tumefaciensrequiring methionine for growth on a solid basal medium were induced by the use ofN-methyl-N′-nitro-N-nitrosoguanidine. In addition to the difference of mutant strains, the extent of methionine dependency differed in a liquid basal medium and in the presence of aspartate or fumarate. When (14C-methyl)-methionine was added to strain WM-11 growing in a prescribed basal medium, incorporation of14C into the cellular “residue” fraction and polar “N-methylated” lipid fraction depended strictly on cellular growth and on external methionine concentration. However, a net synthesis of the “cyclopropane” fatty acid fraction occurred even during the maximal stationary phase if excess methionine was present.
Biosynthesis of Diacetyl in Bacteria and Yeast
Authors: Chuang Linda F. , Collins E. B.
Published: January 2020

Both diacetyl and acetoin were produced by cell-free extracts and cultures of
Pseudomonas fluorescens, Aerobacter aerogenes, Lactobacillus brevis
, and
Saccharomyces cerevisiae
299, whereas only acetoin was produced by cell-free extracts and cultures of
Streptococcus lactis, Serratia marcescens, Escherichia coli
, and
S. cerevisiae
strains 513 and 522. Cell-free extracts that produced diacetyl did not produce it from acetoin; they produced it from pyruvate, but only if acetyl-coenzyme A was was added to the reaction mixtures. Production of diacetyl by
S. cerevisiae
299 was prevented by valine, inhibited by sodium arsenite, and stimulated by pantothenic acid. Valine did not prevent the production of acetoin.
E. coli
and the three strains of
S. cerevisiae
did not decarboxylate α-acetolactate but did use acetaldehyde in the production of acetoin from pyruvate. The other organisms produced acetoin from pyruvate via α-acetolactate.
Water Vapor, Aqueous Ethyl Alcohol, and Heat Activation of
Bacillus megaterium
Spore Germination
Authors: Hyatt Mildred T. , Levinson Hillel S.
Published: January 2020

Dormant spores of
Bacillus megaterium
were activated for germination on glucose by heating them in aqueous suspension (but not if heated dry), by treating them with aqueous ethyl alcohol at 30 C, or by exposing them to water vapor at room temperature. The degree of water vapor activation depended upon the relative humidity, the time, and the temperature of exposure. Activation increased the extent and rate of glucose-induced germination and decreased the average microlag. Extended water vapor treatment also activated spores for germination induced by KI and by
l
-alanine. Spores activated by any of the three treatments were deactivated by treatment at 66 C, either for 18 hr in 100% ethyl alcohol or for 40 hr over P
2
O
5
. Deactivated spores were reactivated by heat, by 5
m
ethyl alcohol, or by water vapor. It is postulated that heating and ethyl alcohol may change the structure of liquid water, so that it is more like water vapor and can more readily penetrate to and hydrate a critical (enzymatic?) spore site, leading to activation.
Microbial Assimilation of Hydrocarbons II. Fatty Acids Derived from 1-Alkenes
Authors: Makula R. , Finnerty W. R.
Published: January 2020

The utilization of 1-alkenes by
Micrococcus cerificans
was investigated with respect to characteristic fatty acid profiles resulting from growth at the expense of these substrates. Saturated fatty acids containing even numbers of carbon atoms were produced from 1-dodecene and 1-tetradecene. Unsaturated fatty acids related to the parent alkene were not detected. The fatty acid profile from 1-pentadecene utilization resulted in the identification of 14-pentadecenoic acid, indicating preferential methyl-group attack. Studies with 1-hexadecene and 1-octadecene indicated simultaneous methyl-group and double-bond attack. Ω-Unsaturated fatty acids related to carbon number of parent alkene and odd-carbon fatty acids one carbon less than the substrate molecule were identified. A mechanism involving double bond epoxidation and oxidative cleavage was supported by measuring the release of formaldehyde. It appears that a dichotomous mechanism is functional in the assimilation of higher carbon number alkenes.
Temperature-sensitive Chloramphenicol Acetyltransferase from
Escherichia coli
Carrying Mutant R Factors
Authors: Mise Katsutoshi , Suzuki Yoshiaki
Published: January 2020

Bacteria carrying temperature-sensitive mutant R factors for chloramphenicol resistance were isolated. In the presence of chloramphenicol, these bacteria grew at 34 C but not at 43 C. The mutations in the chloramphenicol resistance gene of the R factors affected neither the resistance of the bacteria to dihydrostreptomycin and tetracycline nor the stability of the R factors at 43 C. The chloramphenicol acetyltransferase obtained from
Escherichia coli
K-12 carrying the mutant R factors was heat-labile as compared with that from a strain carrying the wild-type R factor. We could not find chloramphenicol acetyltransferase activity in 17 chloramphenicol-sensitive and 5 -resistant strains (selected in vitro) of
E. coli
examined. The results strongly suggest that the chloramphenicol resistance gene of the R factors is the structural gene of the chloramphenicol acetyltransferase rather than the genome controlling the expression of a chromosomal determinant for the enzyme. Furthermore, the studies confirm that the existence of the chloramphenicol acetyltransferase is the primary cause of chloramphenicol resistance of bacteria carrying the R factor. Both the enzyme activity producing the monoacetyl derivative from chloramphenicol and the subsequent formation of the diacetate from the monoacetyl product were heat-labile to the same degree. The results suggest that only one enzyme participates in two steps of chloramphenicol acetylation.
Actinomycin Analogues Containing Pipecolic Acid: Relationship of Structure to Biological Activity
Authors: Formica Joseph V. , Shatkin Aaron J. , Katz Edward
Published: January 2020

Streptomyces antibioticus
synthesizes a mixture of actinomycins which differ at the “imino acid” site of the peptide chains. In the presence of exogenous pipecolic acid, several new actinomycins were synthesized and 70% of the proline in the antibiotic mixture was replaced by the analogue. Three new antibiotics (designated Pip 1α, Pip 1β, and Pip 2) were isolated from culture filtrates, purified, and crystallized. The molar ratio of pipecolic acid to proline was: Pip 1α, 1:0; Pip 1β, 1:1; Pip 2, 2:0. These compounds inhibited the growth and cell division of gram-positive, but not gram-negative, bacteria. The relative inhibitory activity against bacteria,
Escherichia coli
deoxyribonucleic acid (DNA)-dependent ribonucleic acid (RNA) polymerase in vitro, and RNA synthesis in
Bacillus subtilis
and mouse L-929 cells was: actinomycin IV = Pip 1β > Pip 2 > Pip 1α. Protein synthesis in
B. subtilis
was less affected, and DNA synthesis was inhibited only at higher concentrations of antibiotic tested. In L cells, DNA formation was reduced less than RNA synthesis, whereas protein synthesis was not blocked under the experimental conditions employed. Kinetic studies with
B. subtilis
revealed that RNA synthesis was inhibited rapidly followed by an inhibition of protein synthesis. All four antibiotics markedly inhibited the replication of vaccinia virus and reovirus in tissue culture cells, but the production of poliovirus was resistant to the antibiotics. These actinomycins bind to DNA, resulting in an elevation of its T
m
and a decrease in the peak extinction of the actinomycins. The mode of action, as well as the structure-activity relationships among the actinomycins, are discussed relative to a previously proposed model of binding.
Cellular Immunity of Mice Infected with
Listeria monocytogenes
in Diffusion Chambers
Authors: Osebold John W. , DiCapua Richard A.
Published: January 2020

The importance of bringing live bacteria into intimate contact with macrophages as a prerequisite for establishing cellular immunity was investigated. The bacterium
Listeria monocytogenes
was shown to replicate and survive in diffusion chambers implanted in the peritoneal cavities of mice. Humoral substances accruing from host responses to diffusing soluble antigens of the microorganism were unable to inactivate the bacteria. The resistance of mice immunized by subcutaneous inoculation of the live organism always exceeded the resistance of mice with
Listeria
diffusion chamber implants. Animals with sham diffusion chambers were more resistant to a challenge by
L. monocytogenes
than were normal mice. Host resistance was not significantly different between
Listeria
diffusion chamber implant groups and sham diffusion chamber implant groups. The results suggested that direct involvement of macrophages with the parasite is necessary to achieve cellular immunity.
Immunogenicity of Irradiated
Salmonella typhimurium
Cells and Endotoxin
Authors: Previte Joseph J.
Published: January 2020

The effects of high doses of radiation (1, 5, or 20 Mrad) on the toxicity, pyrogenicity, and immunogenicity of
Salmonella typhimurium
cells and endotoxin were studied. Toxicity decreased progressively after exposure to 1, 5, or 20 Mrad. The lethal effect of 1-Mrad exposed cells was greater than that of heat-, acetone-, or alcohol-killed preparations. An amount of 5 Mrad is about a 50% end point in terms of inactivation of the lethal lipopolysaccharide or cell-associated determinants. The fever response to radiation-killed salmonellae decreased between 1- and 20-Mrad exposure. The immunogenicity of 1-Mrad-treated cells usually exceeded that of nonirradiated preparations in mouse-protection tests. With increasing radiation doses, there was a dramatic decrease in, but not an abolition of, immunogenicity. Preparations exposed to 20 Mrad which were nonlethal afforded significant protection. The results are interpreted as a reflection of a dissociation of the primary and secondary toxic determinants of endotoxin after irradiation. The data indicate the potential value of radiation sterilization as a means of production of
Salmonella
vaccine.
Phospholipids of the Thiobacilli
Authors: Barridge Judith K. , Shively J. M.
Published: January 2020

Phosphatidyl glycerol, disphosphatidyl glycerol, and phosphatidyl ethanolamine were found in all of the
Thiobacillus
species studied.
T. thioparus
possessed only these phospholipids.
T. intermedius, T. neapolitanus
, and
T. thiooxidans
contained phosphatidyl-
N
-monomethylethanolamine, and
T. novellus
lipids contained phosphatidyl-
N
-monomethylethanolamine, phosphatidyl-
N-N
-dimethylethanolamine, and phosphatidyl choline, in addition to the three phospholipids common to all of the thiobacilli. Methionine was found to act as a methyl donor in the biosynthesis of the methylated forms of phosphatidyl ethanolamine. Phosphatidyl inositol was not detected in any of the organisms. Changing the nutrient medium did not result in a qualitative change in the phospholipid spectrum of the cultures.
Thermal Stability of
Escherichia coli–Salmonella typhimurium
Deoxyribonucleic Acid Duplexes
Authors: Brenner Don J. , Cowie Dean B.
Published: January 2020

Single-stranded, labeled deoxyribonucleic acid (DNA) fragments from
Escherichia coli
were incubated at 60 and 66 C with a large excess of single-stranded, unlabeled DNA fragments from
E. coli
and
Salmonella typhimurium
. The resulting reassociated DNA was adsorbed to hydroxylapatite and eluted in a series of washes at increasing temperatures. The thermal stability of the reassociated DNA was determined by means of this procedure. Neither the extent of reassociation nor stability of the reassociated
E. coli
DNA was affected by increasing the incubation temperature from 60 to 66 C. The double-stranded molecules resulting from the reassociation of
E. coli
DNA with
S. typhimurium
DNA had a markedly lower thermal stability than reassociated
E. coli
DNA. More reassociation occurred between
E. coli
and
S. typhimurium
at 60 C than at 66 C. In addition, the product of interspecies reassociation occurring at 66 C had a higher thermal stability than that occurring at 60 C. Preliminary results indicate that the decreased thermal stability of the interspecies duplex is in part the result of unpaired bases.
Evidence for an Altered Operator Specificity: Catabolite Repression Control of the Leucine Operon in
Salmonella typhimurium
Authors: Friedman Stephen B. , Margolin Paul
Published: January 2020

A mutation,
GD-1
, in the leucine operon imposed unusual growth characteristics upon a leucine auxotrophic strain bearing the leucine operator mutation,
leu-500
. The strain with the
GD-1
mutation was able to grow on a minimal salts medium when citrate was the sole carbon source, but required leucine when glucose was present. Tests with a large number of carbohydrates suggest that in the strain bearing the
GD-1
mutation the leucine biosynthetic enzymes are under catabolite repressor control. Recombination studies indicate that the
GD-1
mutation is a secondary alteration of the leucine operator at or very close to the site of the
leu-500
mutation. Mutations at the
supX
locus (previously termed
su leu 500
and located on the chromosome between the cysteine B and tryptophan gene clusters) result in elimination of the catabolite repression effect. The data are interpreted as an indication that the
GD-1
and
leu-500
mutations alter the leucine operator with respect to its specificity of response to repressors.
Metabolism of Lactose by
Staphylococcus aureus
and Its Genetic Basis
Authors: Morse M. L. , Hill Katherine L. , Egan J. Barry , Hengstenberg Wolfgang
Published: January 2020

The metabolism of lactose was found to be controlled by three genes: a gene for the synthesis of a β-galactosidase attacking only phosphorylated galactosides; a gene for a protein permitting concentration of phosphorylated galactosides which probably acts by transferring phosphates to them; and a gene regulating the first two structural genes. The three genes are closely linked and may have the same order as in
Escherichia coli
. Galactose-6-phosphate was found to be a better inducer of lactose utilization than is galactose or any other inducer. The inhibition of induction by isopropylthiogalactoside was found to occur at the level of the protein permitting the concentration of galactoside phosphates.
Encystment and Polymer Production by
Azotobacter vinelandii
in the Presence of β-Hydroxybutyrate
Authors: Lin L. P. , Sadoff H. L.
Published: January 2020

Cells of
Azotobacter vinelandii
encysted in Burk's nitrogen-free liquid media which had been supplemented with
n
-butyl alcohol, β-hydroxybutyrate, or crotonate. Butyraldehyde and butyrate did not influence the extent of encystment. In the absence of glucose, β-hydroxybutyrate enhanced the rate and extent of encystment. In the presence of glucose, it promoted abortive encystment, which was manifested by the disorganization of the exine and the release of a highly viscous material into the medium. The soluble, viscous polymer was separated from the medium by a series of ethyl alcohol precipitations and identified as a mucopeptide. It was cleaved by treatment with lysozyme and lysostaphin with a concomitant increase in reducing power. It contained 13.9% N; 56% amino acids, as alanine (alanine, lysine, and glutamic acids); and 42% hexosamines. The polymer appeared to be similar to a noncross-linked peptidoglycan.
Composition and Ultrastructure of
Streptomyces venezuelae
Authors: Bradley S. G. , Ritzi Donna
Published: January 2020

Streptomyces venezuelae
is a filamentous bacterium with branching vegetative hyphae embedded in the substrate and aerial hyphae bearing spores. The exterior of the spore is inlaid with myriads of tiny rods which can be removed with xylene. The spore wall is approximately 30 nanometers thick. Occasionally, it can be seen that the plasma membrane and the membranous bodies within a spore are connected. The spore's germ plasm is not separated from the cytoplasm by a nuclear envelope. The cell walls of the vegetative hyphae, which are about 15 nanometers thick, are structurally and chemically similar to those of gram-positive bacteria. The numerous internal membranous bodies, some of which arise from the plasma membrane of the vegetative hypha, may be vesicular, whirled, or convoluted. Membranous bodies are usually prominent at the hyphal apices and are associated with septum formation. The germ plasm is an elongate, contorted, centrally placed area of lower electron density than the hyphal cytoplasm. The spores differ from the vegetative hyphae, not only in fine structure, but also in the arginine and leucine contents of their total cellular proteins.
Ultrastructural Details in Germinating Sporangiospores ofRhizopus stoloniferandRhizopus arrhizus
Authors: Buckley Patricia M. , Sommer N. F. , Matsumoto T. T.
Published: January 2020

Electron microscope examination of sporangiospore sections fromRhizopus stolonifer(Ehrenb. ex Fr.) Lind. andR. arrhizusFischer revealed details on intracellular organization not previously reported. Aldehyde fixation followed by chromeosmium postfixation permitted clear depiction of ribosomes hitherto unrevealed in these cells. Mitochondria were diversiform. Spore wall structures in the two species were generally similar, but outer contours differed sufficiently to permit easy species identification in examination of sections. The spores of both species abounded in cytosomes, corresponding in size, shape, and heavy-metal “stain” affinities to spherosomes in cells of higher plants. The osmiophilic response of these spherosome-like inclusions was intensified by treatment of sections with thiocarbohydrazide solution and subsequent application of aqueous osmium tetroxide, which strengthens an assumption that they are lipid-rich. The margins of the spherosome-like inclusions in lead citrate-stained sections included dense particles, about 60 A across, whose crystalline-like arrangements suggested that protein as well as lipid was present. Frequent and close associations between the spherosome-like inclusions and various cell membranes suggested that such bodies participate in membrane elaboration during germination.
Fine Structure of
Ectothiorhodospira mobilis
Pelsh
Authors: Remsen C. C. , Watson S. W. , Waterbury J. B. , Trüper H. G.
Published: January 2020

The cell wall structure, arrangement of photosynthetic membranes, and the attachment of flagella of
Ectothiorhodospira mobilis
strain 8112 were examined by using freeze-etching and conventional electron microscopic techniques. The outer coat of the multilayered cell wall is comprised of 50 A repeating subunits, arranged in a regular array. The photosynthetic membranes, which originate from and are attached to the plasma membrane, are arranged in a more complex pattern than previously seen in other bacteria. The tuft of flagella in
E. mobilis
is inserted into a polar organelle. The relationship of this organelle to the polar membrane and the mechanism of attachment of the flagella to the polar organelle is discussed.
Structural and Immunological Studies on the Protoplast Membrane of the Yeast
Candida utilis
Authors: Mendoza C. Garcia , Lopez M. D. Garcia , Uruburu F. , Villanueva J. R.
Published: January 2020

Cell membranes of the yeast
Candida utilis
isolated by lysis of protoplasts have been shown to be lipoprotein in nature. Electron microscopy shows that Mg
++
is responsible for maintaining the integrity of the membrane. A close serological relationship was found between membranes and cell walls isolated from the yeast. This relationship was exhibited not only by membranes obtained by strepzyme treatment but also by those obtained from the action of helicase enzyme. No such relationship existed between membranes and whole cells. Related data have been obtained by treatment of yeasts with different digestive enzymes. All of the results suggest that the protoplast membrane possesses traces of structural cell wall material. This material is detectable by serological tests, but not by electron microscopy.
Partial Purification and Properties of a Trehalase from
Streptomyces hygroscopicus
Authors: Hey Ann E. , Elbein A. D.
Published: January 2020

The enzyme α,α′-glucoside 1-glucohydrolase, which catalyzes the hydrolysis of trehalose, was isolated from
Streptomyces hygroscopicus
and was purified approximately 80-fold. The enzyme was completely specific for trehalose as substrate. None of the other naturally occurring glucose disaccharides exhibited any significant activity. The
p
H optimum for enzymatic activity was found to be 6.5 and the
K
m
was estimated to be approximately 1.8 × 10
−2
m
. The product of the reaction was identified as
d
-glucose by chemical, chromatographic, and enzymatic methods. The presence of this enzyme was demonstrated in several species of
Streptomyces
and related organisms.
Ribonucleic Acid Synthesis in T2-infected
Escherichia coli
During “Stringent” Control
Authors: Sharp Karen , Green Melvin H.
Published: January 2020

The leucine auxotroph
Escherichia coli
2961 exhibited stringent control of net ribonucleic acid (RNA) synthesis during amino acid starvation. After leucine was exhausted from the medium, the rate of uracil incorporation into RNA rapidly decreased to 2 to 4% of the prestarvation value. Infection of the starved cells with T2 phage stimulated uracil incorporation to a level equivalent to that of unstarved, T2-infected cells. The RNA synthesized during leucine starvation of the T2-infected cells consisted of T2 and
E. coli
messenger RNA, but stable ribosomal RNA (23
S
and 16
S
) did not appear to be synthesized. It is concluded that one or more T2-specific proteins are required to shut off host messenger RNA synthesis. Furthermore, transcription of
E. coli
and T2 deoxyribonucleic acid is not necessarily coupled to the translation of messenger RNA during stringent control of net RNA synthesis.
Molar Growth Yields of Certain Lactic Acid Bacteria as Influenced by Autolysis
Authors: Moustafa Hassan H. , Collins E. B.
Published: January 2020

Molar growth yields determined from batch cultures of
Streptococcus diacetilactis
and
S. faecalis
were appreciably greater at the peaks of maximal growth than after continued incubation and considerable autolysis. The higher molar growth yields were about equal to those determined in a continuous culture. Autolysis during logarithmic growth was minimal. The average Y value for adenosine triphosphate (ATP), determined by using limiting concentrations of glucose, galactose, lactose, and maltose for growing
S. diacetilactis
and limiting concentrations of glucose for growing
S. lactis, S. cremoris
, and
S. faecalis
, was 17.0. This is close to the Y (arginine) value of 17.8 determined with
S. faecalis
, but 62% greater than the generally accepted value of 10.5. Data are presented indicating that the often-used Y (ATP) value of 10.5 is erroneously low.
Serological Activity of Protein A ofStaphylococcus aureus:the Precipitinogen as an Antigen for Determining Antibodies by the Passive Hemagglutination Test
Authors: Live I. , Ranu Rajinder S.
Published: January 2020

Tanned sheep erythrocytes have been considered incapable of sensitization with the precipitinogen of protein A ofStaphylococcus aureus, so that the activity of this antigen in serological reactions has so far been studied by means of the agar diffusion test (ADT) only. The precipitinogen of the protein A in this study was found to become attached to the tanned erythrocytes and to sensitize them for the passive hemagglutination test (PHT). It was determined that, in contrast to nonspecific reactivity between normal human serum and the precipitinogen in the ADT, the reaction in the PHT was of specific nature. Of seven species studied, all normal human, dog, and hog sera tested were positive in the PHT. However, the hemagglutinin titers of the sera of the two animal species by far exceeded those of the human sera. The data emphasized the usefulness of the highly sensitive PHT for assaying antibodies to protein A.
Nonsense Suppression in a Multiauxotrophic Derivative of
Escherichia coli
15T
−
: Identification and Consequences of an Amber Triplet in the Deoxyribomutase Gene
Authors: Bockrath R. C. , Osborn Mary , Person Stanley
Published: January 2020

Previously, arginine revertants of
Escherichia coli
WWU, a derivative of
E. coli
15T
−
, have been subdivided by two independent methods: (i) the streak morphology on nutrient agar, and (ii) the pattern of phage growth using amber and ochre mutants of bacteriophage T4. In the first assay, revertants were subdivided into two classes according to the appearance of streaks after incubation on nutrient agar, a thick, even line of growth defining
normal
revertants and a thin, irregular line defining
aberrant
revertants. In the second assay, revertants were classified by the suppressors they contained. The present work demonstrates that revertants containing an amber suppressor show the aberrant morphology and are also able to catabolize thymidine for energy and carbon. This is in contrast to the parent WWU containing no suppressor, which shows a normal morphology and cannot utilize thymidine as an energy source. Revertants containing no suppressor, isolated specifically for their ability to catabolize thymidine, show an aberrant morphology. Together, these results indicate that the aberrant morphology results from suppression of an amber triplet in a gene of the thymidine catabolic pathway. Enzyme assays show the amber triplet to be in the gene specifying deoxyribomutase. It is suggested that the aberrant arginine revertants are analogous to high thymine-requiring mutants and that, in general, high and low thymine-requiring mutants differ from one another in their ability to catabolize deoxyribose-1-phosphate.