bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlation of Ultrastructure in
Azotobacter vinelandii
with Nitrogen Source for Growth
Authors: Oppenheim Joel , Marcus Leon
Published: January 2020

Azotobacter
synthesizes an extensive internal membranous nework when grown with air (N
2
), i.e., under conditions when these bacteria fix nitrogen. Very slight quantities of internal membrane, concentrated mainly about the cell periphery, are formed when
Azotobacter
grows with fixed nitrogen, i.e., ammonia and amino acids. Compared to cells growing with ammonia, cells utilizing atmospheric nitrogen as the sole nitrogen source are smaller in size and volume, grow one-third slower, and lack detectable poly-β-hydroxybutyrate.
Properties of a Soluble Nitrogenase in
Azotobacter
Authors: Oppenheim Joel , Fisher Robert J. , Wilson P. W. , Marcus Leon
Published: January 2020

A nitrogenase system that remains in the supernatant fluid after centrifuging for 3 hr at 180,000 ×
g
can be extracted from
Azotobacter vinelandii
by osmotic lysis of the bacteria. This nitrogenase preparation is oxygen-labile and appears to be similar, though not identical, to that obtained from
Clostridium pasteurianum
. The particulate characteristic and oxygen stability of previously described preparations are likely due to the method of cell disruption, e.g., in the French pressure cell. The data support a nitrogenase model system in the intact cell in which oxygen-labile enzymes are protected from oxygen by the extensive internal membranous system which
Azotobacter
synthesize only when they fix nitrogen.
Amino Sugar Sensitivity in
Escherichia coli
Mutants Unable to Grow on
N
-Acetylglucosamine
Authors: Bernheim Naomi J. , Dobrogosz Walter J.
Published: January 2020

Studies were conducted on two mutants of
Escherichia coli
that lack either glucosamine-6-phosphate deaminase or
N
-acetylglucosamine-6-phosphate deacetylase and which accumulate glucosamine-6-phosphate or
N
-acetylglucosamine-6-phosphate, respectively, when grown in the presence of
N
-acetylglucosamine. The addition of 10
−4
to 10
−5
m
N
-acetylglucosamine to these mutant strains caused a rapid and complete inhibition of growth on substrates that enter the catabolic pathways at or below the level of fructose-6-phosphate. Growth on glucose was inhibited to a lesser degree, whereas only minor inhibition occurred when the pentoses were used as substrates. Growth on gluconate was found to be totally unaffected by these levels of
N
-acetylglucosamine. The objective of this investigation was to determine the nature of this “amino sugar sensitivity” phenomenon and the conditions under which it could be overcome. It was found that this amino sugar sensitivity was abolished when an exogenous source of pentose such as uridine was included in the culture medium. Experiments are described indicating that the accumulated amino sugar phosphate metabolites interfere with an early step in hexose metabolism of both mutants, resulting in a pentose deficiency and consequent inhibition of growth on certain substrates.
Compartmentation in the Induction of the Hexose-6-Phosphate Transport System of
Escherichia coli
Authors: Winkler Herbert H.
Published: January 2020

The induction of the hexose-6-phosphate transport system was investigated. Glucose-6-phosphate (G6P) at concentrations as low as 10
−4
m
was able to induce this system in wild-type cells, as well as in mutants lacking phosphoglucose isomerase or G6P dehydrogenase. Growth in the presence of fructose-6-phosphate (F6P) induced the system only if the cells contained phosphoglucose isomerase. Furthermore, glucose and F6P were found to induce the system only if the extracellular concentration of G6P became appreciable in the medium as a consequence of the leakage of intracellular G6P formed from the glucose or F6P. Intracellular G6P was not an inducer even at high concentrations. The metabolism of glucose inhibited the induction of the hexose-6-phosphate transport system. Hypotheses for this compartmentalization of inducer and membrane-associated induction are presented.
Nucleic Acid Homologies Among Oxidase-Negative
Moraxella
Species
Authors: Johnson John L. , Anderson Robert S. , Ordal Erling J.
Published: January 2020

The deoxyribonucleic acid (DNA) base composition and DNA homologies of more than 40 strains of oxidase-negative
Moraxella
species were determined. These bacteria have also been identified as belonging to the
Mima-Herellea-Acinetobacter
group and the
Bacterium anitratum
group, as well as to several other genera including
Achromobacter
and
Alcaligenes
. The DNA base content of these strains ranged from 40 to 46% guanine plus cytosine. DNA–DNA competition experiments distinguished five groups whose members were determined by showing 50% or more homology to one of the reference strains:
B. anitratum
type B5W,
Achromobacter haemolyticus
var.
haemolyticus, Alcaligenes haemolysans, Achromobacter metalcaligenes
, and
Moraxella lwoffi
. A sixth group comprised those strains showing less than 50% homology to any of the reference strains. Negligible homology was found between strains of oxidase-negative and oxidase-positive
Moraxella
species in DNA–DNA competition experiments. However, evidence of a distant relationship between the two groups was obtained in competition experiments by using ribosomal ribonucleic acid.
Glycolate Uptake by Mutant Strains of
Escherichia coli
K-12
Authors: Ornston L. N. , Ornston M. K.
Published: January 2020

Mutant strains of
Escherichia coli
K-12 were shown to be impaired in their ability to assimilate glycolate-
2
-
14
C
. One strain (Glc-103) has lost the ability to oxidize glycolate; another strain (Glc-102) was relatively impermeable to the compound. A third strain (Glc-104) had undergone a similar loss in permeability, and, in addition, was deranged in the synthesis of either glyoxylate reductase or malate synthase G.
Inducible γ-Butyrobetaine-Degrading Enzymes in
Pseudomonas
Species AK 1
Authors: Lindstedt G. , Lindstedt S. , Midtvedt T. , Tofft M.
Published: January 2020

Activities of γ-butyrobetaine hydroxylase and carnitine dehydrogenase were low in cells of
Pseudomonas
sp. AK 1 grown in the absence of their respective substrates.
Resistance of
Escherichia coli
to Penicillins VIII. Physiology of a Class II Ampicillin-Resistant Mutant
Authors: Nordström Kurt , Burman Lars G. , Eriksson-Grennberg Kerstin G.
Published: January 2020

Class II ampicillin-resistant mutants of
Escherichia coli
are defined as having a twofold increase in penicillinase-mediated ampicillin resistance when determined by colony formation tests on plates. In this paper, one class II mutant has been compared to its parent strain. In liquid medium, the mutant was less resistant than the parent strain both in the absence and in the presence of R1 and R-factor mediating penicillinase activity. The penicillinase activity was found to be almost completely bound to the cells in the parent strain, whereas it was excreted to a great extent in the class II mutant strain. In liquid medium, resistance was well correlated to the cell-bound penicillinase activity, whereas the excreted penicillinases were also of great importance for survival on ampicillin plates. The mutant also had a changed resistance to a great number of other antibacterial drugs. The mutant was found to be more sensitive than the parent strain to osmotic shock, especially when treated with ethylenediaminetetraacetic acid or washed with sodium ions. However, the osmotic stability was restored by the presence of 1 m
m
Mg
2+
ions. The class II mutant was more sensitive than the parent strain to sodium cholate, and it adsorbed the phages T4 and T3-1 at a slower rate than did the parent strain. The two strains adsorbed T6 at the same rate. The class II phenotype could be gradually reversed by increasing concentrations of divalent cations. The pleiotropic changes in the phenotype are apparently unrelated to the specific targets for the antibacterial agents tested. They are secondary consequences of a cell envelope mutation. The findings indicate that the class II mutation mediates a structural change in the lipopolysaccharide of the cell envelope.
Inhibitor of Transfer Ribonucleic Acid Methylases in the Differentiating Slime Mold
Dictyostelium discoideum
Authors: Sharma Opendra K. , Borek Ernest
Published: January 2020

Eight hours after the onset of morphogenesis, an inhibitor of transfer ribonucleic acid methylases appears in differentiating
Dictyostelium discoideum
. The inhibitor is also present in spores. Fifty per cent of the inhibiting activity is lost upon heating at 100 C for 5 min; it is nondialyzable and sensitive to trypsin.
Comparative Allostery of 3-Deoxy-
d
-
Arabino
-Heptulosonate-7-Phosphate Synthetase as a Molecular Basis for Classification
Authors: Jensen Roy A. , Stenmark Sherry L.
Published: January 2020

The allosteric pattern of control for 3-deoxy-
d
-
arabino
-heptulosonate 7-phosphate (DAHP) synthetase has previously been shown to be strongly conserved among the member species of a given genus in bacteria. The implications of this finding as a procedural tool of bacterial phylogeny were pursued by a study of two organisms,
Sporosarcina ureae
and
Aeromonas formicans
, the taxonomic positions of which have been historically controversial.
S. ureae
has characteristics of both
Bacillaceae
and
Micrococcaceae
, and
A. formicans
has characteristics of both
Enterobacteriaceae
and pseudomonads. Since the patterns of control for DAHP synthetase in all four of these microbial groups are different from one another but internally homogeneous within each group, the results obtained from the two test organisms were unambiguous. It was concluded that
S. ureae
is properly classified within
Bacillaceae
, probably deserving generic rank, and that
A. formicans
belongs with the family
Enterobacteriaceae
.
Involvement of the Protocatechuate Pathway in the Metabolism of Mandelic Acid by
Aspergillus niger
Authors: Jamaluddin M. , Rao P. V. Subba , Vaidyanathan C. S.
Published: January 2020

Cell-free extracts of
Aspergillus niger
UBC 814 grown in the presence of
dl
-mandelate oxidized both
d
(−)- and
l
(+)-mandelate via benzoylformate and benzaldehyde to benzoate.
dl
-
p
-Hydroxymandelate was oxidized, presumably through a parallel pathway, to
p
-hydroxybenzoate. A particulate
d
(−)-mandelate dehydrogenase and a supernatant fraction
l
(+)-mandelate dehydrogenase converted their respective substrates to benzoylformate. Both flavine adenine dinucleotide and flavine mononucleotide showed a stimulatory effect on the activity of the
l
(+)-mandelate dehydrogenase. Benzoylformate was decarboxylated to benzaldehyde by an enzyme requiring thiamine pyrophosphate for maximal activity. Two benzaldehyde dehydrogenases dependent on nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), respectively, for their activity dehydrogenated benzaldehyde to benzoate. In the presence of reduced NADP (NADPH), benzoate was oxidized via
p
-hydroxybenzoate and protocatechuate. Reduced NAD could not replace NADPH. Sensitive methods of assay for
d
(−)-mandelate dehydrogenase and benzoylformate decarboxylase are described. The fungal pathway is compared with these systems in bacteria.
Correlation of Bacterial Lipid Composition with Antibiotic Resistance
Authors: Dunnick June K. , O'Leary William M.
Published: January 2020

The correlation of bacterial lipid composition with antibiotic resistance was investigated with particular emphasis on those organisms in which resistance may be related to membrane or envelope structure or function, as in resistance to tetracyclines and polymyxin. Chloroform-methanol-extractable lipids, phosphatidyl ethanolamine fractions, and both fatty acids of these lipid fractions and total fatty acids were studied by using thin-layer chromatography, gas chromatography, and infrared spectroscopy. Consistent quantitative differences were found between the fatty acid compositions of sensitive and resistant strains. Most notable was the fact that, in gram-negative organisms, resistant strains showed decreases in cyclopropane acids as compared with sensitive strains. These changes were found to be inherent in the strains and not due to growth stage or culture age. No significant qualitative differences were noted. In contrast, no such variation in fatty acid content was observed in penicillin-sensitive and resistant strains of gram-positive cocci. As significant alterations of fatty acid composition were noted in gram-negative strains resistant to antibiotics, we suggest that resistance is correlated to membrane or envelope lipid composition.
Accumulation of a Protein Required for Division During the Cell Cycle of
Escherichia coli
Authors: Smith Helene S. , Pardee Arthur B.
Published: January 2020

A heat-labile protein required for division accumulates during the duplication cycle of
Escherichia coli
. Its formation appears to commence shortly after the cell divides, and it reaches a maximal amount shortly before the next division. A plausible mechanism for timing cell division depends on building up the critical amount of this protein. Completion of deoxyribonucleic acid (DNA) replication is also necessary for division to occur, but it does not uniquely initiate division. The evidence for these conclusions comes from heat-shock experiments; heating to 45 C for 15 min delays division increasingly with the age of a cell. A heat shock given near the end of a cycle delays division for about 30 min, whereas at the beginning of the cycle it hardly affects division. The net result is synchronization of cell division. The effect of heat is increased in bacteria which have incorporated
p
-fluoro-phenylalanine into their proteins. When the incorporation is early and the heat shock is late in the cycle, division is delayed by about 30 min, indicating that the division protein is synthesized early even though its sensitivity is not observed until later. At any time in the cell cycle, heat shock simply delays total protein and DNA synthesis (
3
H-thymidine uptake) for approximately 14 min. DNA replication and cell division are thus discoordinated, since DNA replication is not synchronized by the treatment.
Behavior of Coliphage Lambda in Hybrids BetweenEscherichia coliandSalmonella
Authors: Baron L. S. , Penido Elisa , Ryman I. R. , Falkow Stanley
Published: January 2020

Salmonella typhosahybrids able to adsorb lambda were obtained by matingS. typhosarecipients withEscherichia coliK-12 donors. After adsorption of wild-type λ to theseS. typhosahybrids, no plaques or infective centers could be detected.E. coliK-12gal+genes carried by the defective phage λdgwere transduced toS. typhosahybrids with HFT lysates derived fromE. coliheterogenotes. The lysogenic state which resulted in theS. typhosahybrids aftergal+transduction differed from that ofE. coli. Ability to produce λ, initially present, was permanently segregated by transductants of theS. typhosahybrid.S. typhosalysogens did not lyse upon treatment for phage induction with mitomycin C, ultraviolet light, or heat in the case of thermoinducible λ. A further difference in the behavior of λ inSalmonellahybrids was the absence of zygotic induction of the prophage when transferred fromE. coliK-12 donors toS. typhosa. A new λ mutant class, capable of forming plaques onS. typhosahybrids refractory to wild-type λ, was isolated at low frequency by plating λ onS. typhosahybrid WR4254. Such mutants have been designated as λsx, and a mutant allele of λsxwas located between the P and Q genes of the λ chromosome. Plaques were formed also on theS. typhosahybrid host with a series of λi21hybrid phages which contain the N gene of phage 21. The significance of these results in terms ofSalmonellaspecies as hosts for λ is discussed.
Facilitation of the Transfer of R Factor by the Resident R Factor
Authors: Yoshikawa Masanosuke , Sakai Katsuko
Published: January 2020

Transfer of some R factors were shown to be facilitated by resident R factors. The sex factor itself may be responsible for this phenomenon.
Lack of Murein in a Formamide-Insoluble Fraction from the Stable L-Form ofStreptococcus faecium
Authors: King James R. , Prescott Benjamin , Caldes George
Published: January 2020

Formamide-insoluble material was isolated from the L-form ofStreptococcus faeciumstrain F24, but this material was not murein.
Derepression of β-Lactamase (Penicillinase) in
Bacillus cereus
by Peptidoglycans
Authors: Ozer Joy Hochstadt , Lowery Dolores L. , Saz Arthur K.
Published: January 2020

In
Bacillus cereus
569 a cellular inducer of β-lactamase was isolated which has the same constituents and basic structure as the soluble peptidoglycan found in sporulation, extracts from spores, and germination extracts, and which was previously called “spore-peptide.” The material has been extensively purified and characterized. Two acid-soluble, high-molecular-weight peptidoglycan fractions containing muramic acid, glucosamine, diaminopimelic acid,
d
-aspartate, and
d
- and
l
-alanine, -lysine, -glycine, and -glutamate, distinguishable on the basis of size and different amino acid to amino sugar ratios, have been found to be responsible for the observed induction. Both fractions are capable of inducing high levels of β-lactamase in concentrations lower than those of benzyl penicillin required for optimal induction. Several experiments also suggest that it is the accumulation of such soluble peptidoglycan in penicillin-treated cells which leads to induction of β-lactamase and not the penicillin itself. The “spore-peptide” inducer becomes available during sporulation, and endogenous derepression of β-lactamase activity occurs simultaneously. Such derepression also occurs in a strain of
B. cereus
very sensitive to penicillin and in which both uninduced as well as “spore-peptide”-induced β-lactamase is a small fraction of that produced by the typical penicillinase producer. These results suggest that β-lactamase in
B. cereus
functions in cell wall metabolism during sporulation.
Mapping of the
nadB
Locus Adjacent to a Previously Undescribed Purine Locus in
Escherichia coli
K-12
Authors: Tritz Gerald J. , Matney Thomas S. , Gholson Robert K.
Published: January 2020

It is proposed that all mutants blocked in the de novo pathway of nicotinamide adenine dinucleotide biosynthesis be designated
nad
rather than
nic
. It is further suggested that mutants blocked in the pyridine nucleotide cycle be designated
pnc
. The
nadB
locus and a previously unidentified
pur
locus are cotransducible. These two loci have been mapped near minute 49 on the standard genetic map of
Escherichia coli
. The order of genes in that region is
purC-guaB-purG-glyA-pur-nadB-tyrA-pheA
.
Dark-Recovery Processes in
Escherichia coli
Irradiated with Ultraviolet Light III. Effect of
rec
Mutations on Recovery of Excision-Deficient Mutants of
Escherichia coli
K-12
Authors: Ganesan Ann K. , Smith Kendric C.
Published: January 2020

Mutants of
Escherichia coli
K-12 unable to excise pyrimidine dimers from their deoxyribonucleic acid (DNA) because of a
uvr
mutation show a higher survival when plated on a minimal salts medium after exposure to ultraviolet radiation than when plated on a complex medium such as nutrient agar containing yeast extract. This response has been called minimal medium recovery (MMR). Recovery of
uvr
mutants can take place in liquid as well as on solid medium, but not in buffer or under conditions of amino acid starvation that do not permit cell growth and normal DNA replication. MMR can thus be distinguished from the recovery of recombination-deficient (
rec
−
uvr
+
) derivatives of K-12 which can occur under conditions where growth is not possible. Because MMR is characteristic of excision-defective mutants, it evidently reflects a type of repair independent of excision. We have obtained genetic evidence that MMR is determined by the
rec
genes, which also control recombination in K-12. Cells carrying a
uvr
mutation together with
recA13, recA56, recB21
, or
recC22
failed to show MMR and were more sensitive to ultraviolet radiation than either their
rec
+
uvr
−
or
rec
−
uvr
+
parents. The
rec
+
uvr
−
derivatives obtained from
recA uvr
−
strains by transduction or by reversion regained the capacity for MMR. Our results indicate that inactivation of any one of the three genes,
recA, recB
, or
recC
, prevents cells from showing MMR.
Physiological Advantage of the Mechanism of the Tryptophan Synthetase Reaction
Authors: Manney Thomas R.
Published: January 2020

Indole-accumulating and indole-utilizing tryptophan synthetase mutants of
Saccharomyces cerevisiae
were found to form complementing diploids with unusual growth properties. These strains grew at nearly the wild-type exponential rate, but only after an abnormally prolonged lag period of a duration that depended on the initial cell density. The exaggerated lag was reduced by adding low concentrations of indole in the medium. The growth properties were interpreted to be a consequence of the inability of these strains to synthesize tryptophan by the normal mechanism.
Relation of Lipopolysaccharide and Fatty Acid Ester Release to the Ethylenediaminetetraacetic Acid Alteration of Permeability in
Enterobacteriaceae
Authors: Winshell E. B. , Neu H. C.
Published: January 2020

Escherichia coli
subjected to cold osmotic shock released 30 to 40% of their fatty acid esters and 42% of their cellular hexosamine. In contrast,
Enterobacter
, although they released 40% of fatty acid esters, release only 25% of hexosamine.
Proteus
released less than 15% of either fatty acid esters or hexosamine. These differences are taken to explain the differences among the
Enterobacteriaceae
in releasing surface enzymes after osmotic shock. It is felt that the release of additional lipopolysaccharide after osmotic shock is necessary for the release of surface enzymes that are not freed by ethylenediaminetetraacetic acid-tris(hydroxymethyl)aminomethane exposure.
Transduction in
Bacillus cereus
by Each of Two Bacteriophages
Authors: Yelton David B. , Thorne Curtis B.
Published: January 2020

The ability of phage CP-51 to mediate transduction both homologously and heterologously in some of its hosts was investigated. CP-51 was shown to transduce
Bacillus cereus
strains 6464, 9139, and T in addition to 569 which was reported earlier from this laboratory. Furthermore, CP-51 grown on
B. thuringiensis
was shown to transduce some mutants of
B. cereus
. During this investigation, a second transducing phage for
B. cereus
569 was isolated from lysates of phage CP-51 grown on
B. cereus
6464. This phage, designated CP-53, is carried by wild-type strain 6464 possibly as prophage. All auxotrophic mutants of
B. cereus
569 tested, those requiring tryptophan, histidine, methionine, and leucine, were transduced to prototrophy by CP-53. Electron micrographs of the two phages revealed that CP-51 has a tail core surrounded by a contractile sheath and CP-53 has a long flexible tail without a contractile sheath. CP-53 is stable in the cold, whereas CP-51 is rapidly inactivated at 4 C.
Genetic and Physiological Aspects of Resistance to 5-Fluoropyrimidines in
Saccharomyces cerevisiae
Authors: Jund Richard , Lacroute François
Published: January 2020

Mutants resistant to 5-fluorouracil, 5-fluorocytosine, and 5-fluorouridine were selected in yeast, and the mechanisms of their resistance were investigated. The investigated mutations map in seven different loci. (i) A mutation at the locus FUI 1 gives specifically resistance to 5-fluorouridine. (ii) Two loci are involved in a specific 5-fluorocytosine resistance: a mutation at locus FCY 1 produces a loss of cytosine deaminase activity; a mutation at locus FCY 2 results in the loss of the activity of a cytosine-specific permease. (iii) A mutation at the locus FUR 4 gives a simultaneous resistance to 5-fluorouracil and to 5-fluorouridine by loss in the activity of the uracil-specific permease. (iv) We found three types of mutants in the locus FUR 1. One is dominant and weakly resistant to 5-fluorouracil, 5-fluorocytosine, and 5-fluorouridine. The two others are recessive and are unable to catalyze one of the steps involved in uracil transformation into uridine 5′-monophosphate; this block-age explains their strong resistance to 5-fluorouracil and 5-fluorocytosine. Of these two mutants, one is resistant to 5-fluorouridine and the other is not. (v) Mutations at locus FUR 2 give resistance to 5-fluorouracil, 5-fluorocytosine, and 5-fluorouridine. These mutations are dominant and lead to a loss in the feedback regulation of the aspartic transcarbamylase activity by uridine triphosphate. (vi) The mutants FUR 3 are resistant to 5-fluorocytosine and 5-fluorouridine. They are dominant and physiologically related to the mutants of the locus FUR 1 but their mechanism of resistance is not understood.
Nature of the Inactivation of the Isocitrate Dehydrogenase from an Obligate Halophile
Authors: Hubbard Jerry S. , Miller Alan B.
Published: January 2020

The nicotinamide adenine dinucleotide phosphate-specific isocitrate dehydrogenase (ICDH) of
Halobacterium cutirubrum
is rapidly inactivated at low NaCl levels. From sucrose gradient analysis, it was estimated that the active ICDH has an
S
20,w
of 5.3 and a molecular weight of 75,000. The inactivation by removal of NaCl causes an unfolding of the protein yielding a less-compact conformer with an
S
20,w
of 2.0. This inactivation apparently causes internal sulfhydryl groups to be exposed. Over 90% of the initial activity can be restored by dialyzing the inactivated ICDH against 4
m
NaCl, provided that the exposed sulfhydryl groups are protected with dithiothreitol. The ICDH is permanently inactivated when the sulfhydryl groups are oxidized or alkylated. The alkylation of the inactive ICDH was demonstrated by treatment with
14
C-
N
-ethyl maleimide. Sucrose gradient analysis showed that
14
C was bound to a protein with sedimentation properties identical to that of reversibly inactivated ICDH, i.e., an
S
20,w
of 2.0. Much less
14
C was bound when active ICDH was treated with
14
C-
N
-ethyl maleimide. The
H. cutirubrum
ICDH resembles other bacterial isocitrate dehydrogenases in being susceptible to concerted feedback inhibition by oxalacetate and glyoxalate.
Mechanism of Action of Nalidixic Acid on Conjugating Bacteria
Authors: Bouck Noel , Adelberg Edward A.
Published: January 2020

When nalidixic acid, a specific and effective inhibitor of cellular deoxyribonucleic acid synthesis, is added to conjugating bacteria at any time during mating, it stops genetic transfer provided the donor bacterium is sensitive to the drug. When this inhibition is released by the removal of the nalidixic acid, transfer does not resume at the point on the chromosome where it was stopped, but begins again at the transfer origin. Curves relating the effects of various low doses of nalidixic acid to the frequency of recombination reveal that several “hits” are necessary to inhibit recombination for early markers. The number of required “hits” decreases as the distance of the marker from the transfer origin increases. Transfer between drug-resistant cells may also be inhibited by nalidixic acid. The effect of high drug doses on matings between resistant cells is similar to that of low drug doses on matings with a sensitive male.
Regulation of Ribonucleic Acid Synthesis in
Escherichia coli
During Diauxie Lag: Accumulation of Heterogeneous Ribonucleic Acid
Authors: Jacobson Lewis A.
Published: January 2020

The synthesis of ribonucleic acid (RNA) and of protein in
Escherichia coli
during glucose-lactose diauxie lag have been examined. The rate of RNA synthesis is about 7%, of the corresponding rate during exponential growth and the rate of protein synthesis 10 to 15%. Inhibition of RNA synthesis occurs to the same extent in both
rel
and
rel
+
strains. The RNA which accumulates during 20 min in diauxie lag is composed of about 50% ribosomal and transfer RNA species and about 50% of a fraction which resembles messenger RNA (mRNA) in its heterogeneous sedimentation properties. Decay of the heterogeneous fraction occurs in the presence of glucose and actinomycin D with a half-life of 3 min, the same as that of pulse-labeled mRNA; however, during the diauxie lag, the half-life of this RNA is about 25 min. Accumulation of the heterogeneous RNA is further increased when protein synthesis is blocked by chloramphenicol. The data suggest that the disproportionate accumulation of mRNA during diauxie lag and energy source shift-down may be attributed at least in part to increased stability of mRNA, but do not rule out a preferential synthesis of mRNA.
Ultrastructural Features of
Mycoplasma pneumoniae
Authors: Biberfeld Gunnel , Biberfeld Peter
Published: January 2020

The ultrastructure of
Mycoplasma pneumoniae
cultivated in broth on glass and plastic surfaces was studied by scanning and transmission electron microscopy. The organisms grew as filaments, which by over-crossing eventually formed a dense network on the surface and in colonies composed mainly of rounded and elongated forms. The filaments were usually thinner at the ends and terminated with a knob-like structure. Some filaments possessed short ramifications which also ended with a knob, and others showed constrictions. Sectioned organisms were seen to contain ribosome-like structures. Many organisms had a specialized structure at their thinner end, which consisted of a dense rod surrounded by electron-lucent cytoplasm and ending with a platelike thickening.
Characterization of the Lipids of
Butyrivibrio fibrisolvens
Authors: Kunsman Joseph E.
Published: January 2020

Butyrivibrio fibrisolvens
strain D-1 was grown on a lipid-free chemically defined medium. The lipids were extracted with chloroform-methanol and separated into nonpolar and polar fractions by silicic acid column chromatography. Further separations were made by preparative thin-layer chromatography. The lipid fractions were identified by specific staining reactions and

R
F

values, by phosphorus and nitrogen determinations, by chromatography of hydrolysis products, and by the use of infrared spectroscopy. The major nonpolar lipid was free fatty acid. Four major polar lipids were identified: phosphatidylethanolamine, phosphatidyl glycerol, lipoaminoacid, and glycolipid. The lipoaminoacid contained alanine, leucine, and isoleucine. The glycolipid contained galactose. The major fatty acids identified were C16:0 and C18:1. The significance of the presence of lipoaminoacid is discussed.
Amino Acid Transport by the Filamentous Fungus
Arthrobotrys conoides
Authors: Gupta Rishab K. , Pramer David
Published: January 2020

Uptake of
l
-valine by germinated spores of
Arthrobotrys conoides
has all the characteristics of a system of transport that requires an expenditure of energy by the cells. It is dependent on temperature and has an energy of activation of 16,000 cal/mole. Uptake is optimal at
p
H 5 to 6.
l
-Valine accumulated against a concentration gradient and is not lost from the cells by leakage or exchange. The process requires energy supplied by the metabolic reactions that are inhibited by catalytic amounts of 2,4-dinitrophenol and azide. The kinetics of the system are consistent with a mechanism of transport that depends on a limited number of sites on the cell surface, and the Michaelis constant for the system is 1.5 × 10
−5
to 7.5 × 10
−5
m
. Modification of the amino or carboxyl group abolishes
l
-valine uptake. The process is competitively inhibited by
d
-valine, glycine, and other neutral amino acids (
K
i
= 1.5 × 10
−5
to 4.0 × 10
−5
m
), indicating a lack of stereospecificity, and also indicating that aliphatic side chain is not required for binding with the carrier. The transport system has less affinity for acidic amino acids (glutamic and aspartic acids) than neutral amino acids, and a greater affinity for basic amino acids (histidine, lysine, and arginine). The range of affinity is in the order of 100, as measured in terms of
K
i
values for various compounds. The data presented provide suggestive evidence that the uptake by
A. conoides
of all amino acids except proline is mediated by a single carrier system that possesses an overall negative charge.
Pseudouridylate Synthetase of
Escherichia coli
: Correlation of Its Activity with Utilization of Pseudouridine for Growth
Authors: Breitman T. R.
Published: January 2020

A direct correlation exists between the pseudouridylate synthetase activity and the ability of pyrimidine auxotrophs of
Escherichia coli
to grow on pseudouridine.
Amino Acid Sequence of the Murein of
Planococcus
and Other
Micrococcaceae
Authors: Schleifer K. H. , Kandler O.
Published: January 2020

The amino acid composition and amino acid sequence of the murein (peptidoglycan) of 10 strains of planococci were studied. It is shown that the peptide subunit consists of muramyl-
l
-alanyl-γ-
d
-glutamyl-
l
-lysyl-
d
-alanine. The cross-linking of two adjacent peptide subunits is mediated by
d
-glutamic acid which is bound to the ε-amino group of lysine by its γ-carboxyl group and to the carboxyl group of
d
-alanine of an adjacent peptide subunit by its amino group. About 20 to 25% of the peptide subunits are not cross-linked. The murein structure of the different species and strains of
Micrococcus, Staphylococcus
, and
Sarcina
are compared. It is evident that the murein structure is a very good criterion for grouping the micrococci. In addition, some of these groups are fairly well defined by physiological properties as well as by their guanine + cytosine content of the deoxyribonucleic acid e.g.,
Micrococcus, Staphylococcus, Planococcus, Sarcina ureae
. Other groups, represented by a single or a few strains only, such as
M. varians
NTCC 7281,
M. radiodurans, M. freudenreichii
ATCC 407, and
M. luteus
ATCC 398, need further investigation.
Relationship of Nuclear Segregation and Macroconidial Germination in
Microsporum gypseum
Authors: Leighton T. J. , Stock J. J.
Published: January 2020

Microsporum gypseum
macroconidia germinated at 37 C possessed from one to eight nuclei per germinated spore compartment. The distribution of nuclei per spore compartment was the result of a random packaging of nuclei from the available nuclear population. Partial inhibition of germination by incubation at 25 C or at 37 C in the presence of 10
−4
m
phenyl methyl sulfonyl-fluoride resulted in an enrichment of germinated spores containing high numbers of nuclei per compartment. The selection for higher nuclear numbers was statistically significant. Compartments possessing high numbers of nuclei appeared to be precommitted to spore germination since they were not sensitive to germination inhibition. The effect of incubation temperature variation on spore germination is discussed with respect to the organism's natural environment.
Factors Affecting Deoxycholate Inactivation and Mg
++
Reactivation of
Bacillus megaterium
KM Membrane Nicotinamide Adenine Dinucleotide (Reduced Form) Oxidase
Authors: Yu L. , Wolin M. J.
Published: January 2020

Decay of the reduced nicotinamide adenine dinucleotide oxidase of
Bacillus megaterium
KM membranes was prevented by storage in 10% (v/v) glycerol or 0.4% bovine serum albumin. Differential rates of solubilization of components of the oxidase system by 0.4% deoxycholate was demonstrable at 4 C. The amount of Mg
++
necessary for maximal oxidase reactivation increased with increasing amounts of deoxycholate-inactivated oxidase. Mg
++
activation of deoxycholate-inactivated oxidase was partially temperature-dependent. Maximal activation was observed at 37 C, but only partial activation took place at 4 C. A small amount of deoxycholate was required for Mg
++
activation of deoxycholate-inactivated oxidase. Two
p
H optima were found for Mg
++
activation of deoxycholate-inactivated oxidase,
p
H 5.3 and 7.3. Significant amounts of activation of the inactive oxidase occurred in the absence of Mg
++
with an optimum at
p
H 5.0, with essentially no Mg
++
-independent activation demonstrable at
p
H 7.0.
Biosynthesis of Ergothioneine and Hercynine by Fungi and
Actinomycetales
Authors: Genghof Dorothy S.
Published: January 2020

Unlike other bacteria, aerobic members of the order
Actinomycetales
show a close biochemical relationship to the fungi by their capacity to synthesize hercynine and ergothioneine. The myxomycete
Physarum polycephalum
, possessing the same synthetic ability, also shows this relationship. Contrariwise, the unusual position of yeasts as fungi is indicated by the inability of all yeastlike
Ascomycetes
and all except a few false yeasts to synthesize these two betaines.
Intracellular Substrates for Endogenous Metabolism During Long-Term Starvation of Rod and Spherical Cells ofArthrobacter crystallopoietes
Authors: Boylen Charles W. , Ensign Jerald C.
Published: January 2020

Cells ofArthrobacter crystallopoietes, harvested during growth as spheres and as rods, were starved by shaking at 30 C in phosphate buffer for 30 days, during which time they maintained 100% viability. Changes in cellular components and the activity of specific enzyme pathways were monitored. A glycogen-like polysaccharide comprised 40% of the dry weight of growing spherical cells and 10% of the dry weight of rod cells. This material was utilized at approximately the same rate, on a percentage basis, during starvation of both cell forms. The rods degraded intracellular protein at approximately twice the rate of the spheres. At the end of 30 days, the rods had degraded 40% and the spheres 20% of their initial content of protein. Ribonucleic acid (RNA) was degraded significantly more rapidly in the rods. After 30 days starvation, 85 and 32% of the initial RNA of rods and spheres, respectively, had been depleted. Magnesium ion followed this same general pattern; the rods lost 65% and the spheres 45% of their initial content during 28 days of starvation. Deoxyribonucleic acid increased by 20% during the first few hours of starvation of both cell forms and then remained constant. The ability of glucose-, succinate-, and 2-hydroxypyridine (2-HP)-grown cells to oxidize glucose remained constant during 14 days of starvation. The ability of succinate-grown cells to oxidize succinate decreased rapidly during the first few hours of starvation to a rate which remained constant for 14 days. Cells adapted to growth on 2-HP completely lost their ability to oxidize this substrate after 3 days starvation.
Role of Thiosulfate in Bisulfite Reduction as Catalyzed byDesulfovibrio vulgaris
Authors: Findley John E. , Akagi J. M.
Published: January 2020

Studies with35S-labeled substrates were conducted to investigate the pathway involved in the reduction of sulfite to sulfide by cell-free extracts of the sulfate-reducing organismDesulfovibrio vulgaris. The results showed that accumulation of thiosulfate occurred when crude extracts were incubated under appropriate conditions with sulfite as substrate. With labeled sulfite as substrate, thiosulfate with equal distribution of radioactivity in both sulfur atoms was formed. When the rates of formation of35S2−from inner- and outer-labeled thiosulfate were compared, the rate of formation from outer-labeled thiosulfate was greater. Time studies with S-35SO32−showed an increase of35S2−with time and an increasing ratio of doubly labeled to inner labeled thiosulfate remaining in the reaction mixture. From these studies it is concluded that thiosulfate is a stable intermediate formed from sulfite during the reduction of sulfate byD. vulgaris. Both sulfur atoms are derived from sulfite; during the utilization of thiosulfate, the outer sulfur is reduced to sulfide and the inner sulfur recycles through a sulfite pool.
Evidence for Genetic Interaction Between Plasmid and Chromosomal Penicillinase Linkage Groups in
Staphylococcus aureus
Authors: Vernon Edith G. , Sweeney Helen M. , Cohen Sidney
Published: January 2020

Spontaneous reciprocal recombination was detected between the regulator genes of penicillinase plasmids and chromosomal penicillinase linkage groups of
Staphylococcus aureus
. The frequency of recombination varied with different penicillinase linkage groups.
Mechanism of Action of the Antifugal Agent Polyoxin D
Authors: Endo Akira , Kakiki Kazuo , Misato Tomomasa
Published: January 2020

The antibiotic polyoxin D was shown to inhibit the incorporation of
14
C-glucosamine into cell wall chitin in
Neurospora crassa
at levels which were comparable with those required for inhibition of fungal growth. At the same time, the antibiotic increased the accumulation of a nucleotide, which was identified as uridine diphosphate (UDP)-
N
-acetylglucosamine, indicating inhibition of chitin synthesis. Chitin synthetase (UDP-
N
-acetylglucosamine: chitin
N
-acetylglucosaminyl transferase, EC 2.4.1.16) of
N. crassa
was found to be strongly inhibited by polyoxin D, as determined by the transfer of
14
C-
N
-acetylglucosamine from
14
C-UDP-
N
-acetylglucosamine to the particulate fraction. The inhibition was competitive with respect to UDP-
N
-acetylglucosamine and specific for chitin synthetase. The
K
i
for polyoxin D in the reaction was 1.40 × 10
−6
m
, and the
K
m
for UDP-
N
-acetylglucosamine was 1.43 × 10
−3
m
. The formation of osmotically sensitive, protoplast-like structures, when the fungus
Cochliobolus miyabeanus
was grown in the presence of polyoxin D, also suggested that the primary site of action of polyoxin D was in the formation of cell wall structures.
Mutant Analysis and Enzyme Subunit Complementation in Bacterial Bioluminescence in
Photobacterium fischeri
Authors: Nealson Kenneth H. , Markovitz Alvin
Published: January 2020

Chemical mutagens were used to obtain mutants deficient in bioluminescence in the marine bacterium
Photobacterium fischeri
strain MAV. Acridine dyes were effective in the production of dark mutants but not in the production of auxotrophs. These dark mutants were all of one type and appeared to contain lesions blocking the synthesis of luciferase. ICR-191 was especially effective in the production of aldehyde mutants, i.e., dark strains that luminesce when a long-chain aldehyde such as
n
-decanal is added to them. However, other mutant types were isolated after treatment with ICR-191.
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine induced many bioluminescence-deficient types with respect to both the site of the lesion and the quantitative effect on the luminescent system. We characterized the dark and dim mutants with respect to their response to exogenous decanal, levels of in vivo and in vitro luminescence, and their rates of reversion to wild type. In addition, the luciferases of the mutant strains were examined by subunit complementation. On the basis of these analyses, we identified mutants which synthesize altered luciferase, strains which are deficient in synthesis of luciferase, and aldehyde mutants. The results of analysis of luciferase from the aldehyde mutants and the complementation studies indicate that the lesions in these strains are in the luciferase itself. Results obtained with wild-type cells grown in minimal medium, and aldehyde mutant cells grown either in complete or minimal medium, indicate that a “natural aldehyde factor” is involved in in vivo light emission. These same studies showed that the long-chain aldehyde(s) could only partially substitute for the natural “aldehyde factor.” The possibility that the in vivo aldehyde factor is not a long-chain aldehyde is discussed.
Studies on Resistance Transfer Factor Deoxyribonucleic Acid in
Escherichia coli
Authors: Silver Richard P. , Falkow Stanley
Published: January 2020

A variant of the derepressed R factor, R1, which does not contain any of the drug resistance markers, and represents, in large part, the resistance transfer factor (RTF) was studied in
Escherichia coli
. RTF deoxyribonucleic acid (DNA) was specifically labeled in a female cell after conjugation. Physical characterization of the molecule showed that RTF possessed an average molecular weight of 50 × 10
6
daltons and a buoyant density of 1.709 g/cm
3
. By comparison to R1, we calculate that the region of DNA carrying the drug resistance genes is therefore about 20% of the R1 molecule and has a buoyant density of approximately 1.716 g/cm
3
. These results support the hypothesis that the single species of R-factor DNA observed in
E. coli
represents a composite of the 1.709 and 1.716 g/cm
3
replicons seen in
Proteus
.
Recombination-Deficient Mutants of Colicinogenic
Salmonella typhimurium
Detected by Their Failure to Produce Colicin
Authors: MacPhee Donald G.
Published: January 2020

Survivors of nitrosoguanidine-treated cultures of a colicinogenic strain of
Salmonella typhimurium
were tested for spontaneous production of colicin E1. Of about 1,000 colonies tested, 13 produced no (or very narrow) colicin zones. Four of these isolates proved to be more sensitive to ultraviolet (UV) light, X rays, and methyl methane sulfonate than the parent strain and did not show enhanced production of colicin when treated with mitomycin C (which acts as an inducer on wild-type cells). Further studies showed that these isolates were of two classes. Three mutants were extremely sensitive to UV, failed to show spontaneous release of two temperate phages, and were infertile as recipients in transduction or in an Hfr cross although they accepted an F′ factor normally. These independently isolated mutants were inferred to be recombination-deficient; one of them had the additional property of increased spontaneous mutability at two loci. The other colicin-nonreleasing isolate was only moderately sensitive to UV, showed enhanced spontaneous release of two temperate phages, and was of approximately normal fertility as a recipient in transduction or conjugation.
Degradation of Enteric Bacterial Deoxyribonucleic Acid by the
Escherichia coli
B Restriction Endonuclease
Authors: Ford Eric , Boyer Herbert W.
Published: January 2020

The deoxyribonucleic acid of five different genera of enteric microorganisms was shown to be degraded by the
Escherichia coli
B restriction endonuclease.
Competence Factor Production in Chemically Defined Media by Noncompetent Cells of Group H
Streptococcus
Strain Challis
Authors: Leonard C. Gomez , Ranhand Jon M. , Cole Roger M.
Published: January 2020

Chemically defined media for competence factor (CF) production by group H
Streptococcus
strain Challis-6 are described. CF is produced by noncompetent cells in a glutamate-free medium in which the cells cannot attain competence and by cells prior to their competence development in a glutamate-containing medium. Glutamate was required for competence development, but was not necessary for growth or CF production. Exacting cultural conditions required for the consistent production of relatively high amounts of CF in defined medium and for its recovery are detailed. The most important requirements include the selection of isolates (like Challis-6) which grew well in another defined medium, early harvest of CF because of its demonstrated instability on continued incubation in defined medium, incubation at 37 C, and the addition of glucose. The CF production was more rapid with increasing inocula and with reduced aeration. Aspartate, cystine, and NaCl were not required. Under the conditions described, large amounts of CF were consistently obtained in the culture filtrates of Challis-6 as measured by the induction of competence in strain Wicky cells and their subsequent transformation at frequencies of 6% or greater.