bluuebunny/crossref_metadata_2025 huggingface dataset:
Deoxyribonucleic Acid-Deoxyribonucleic Acid Hybridization Assay for Replication Origin Deoxyribonucleic Acid of
Escherichia coli
Authors: Kuempel Peter L.
Published: January 2020

Deoxyribonucleic acid (DNA)-DNA hybridization on nitrocellulose filters can be used to assay for replication origin DNA from
Escherichia coli
if the DNA attached to the filters is enriched for the replication origin sequences. Such DNA can be readily isolated from very rapidly growing cells. When low amounts of this DNA were attached to filters, radioactively labeled DNA from the replication origin hybridized 1.7 times as well as radioactive replication terminus DNA. Under identical conditions, radioactively labeled DNA from exponentially growing cells hybridized only 1.3 times as well as radioactive replication terminus DNA. The replication origin, replication terminus, and randomly labeled DNA hybridized with similar efficiencies to filters containing DNA isolated from cells incubated in the absence of required amino acids. This DNA appeared to have all sequences present at equal frequencies. The hybridization assay was used to demonstrate that the DNA synthesized shortly after the addition of amino acids to cells previously deprived of required amino acids was primarily from the replication origin and then rapidly became similar to DNA synthesized by exponentially growing cells.
Development of a Membrane-Bound Respiratory System Prior to and During Sporulation inBacillus cereusand Its Relationship to Membrane Structure
Authors: Lang Dennis R. , Felix J. , Lundgren D. G.
Published: January 2020

Bulk membrane fragments were prepared from cells ofBacillus cereusATCC 4342 harvested at different stages of growth and sporulation and examined for enzymes involved in electron transport functions. The presence of succinate: DCPIP oxidoreductase (EC 1.3.99.1), succinate: cytochromecoxidoreductase (EC 1.3.2.1), NADH:DCPIP oxidoreductase (EC 1.6.99.1), NADH:cytochromecoxidoreductase (EC 1.6.2.1), succinate oxidase [succinate: (O2) oxidoreductase, EC 1.3.3.1], and NADH oxidase [NADH:(O2) oxidoreductase, EC 1.6.3.1] were demonstrated in membrane fragments from vegetative cells, early and late stationary-phase cells, and in cells undergoing sporulation. During the transition from a vegetative cell to a spore, there was a significant increase in the levels of enzymes associated with energy production via the electron transport system. Cytochromes of thea, b, andctype were detected in all membrane preparations; however, there was a marked increase in the level of cytochromes by the end of vegetative growth which remained throughout sporulation; there were no qualitative changes in the cytochromes throughout growth and sporulation. Sporulation was inhibited by cyanide, stressing the significance of the electron transport system. Enzyme activities were partially masked in washed membrane fragments; however, unmasking (stimulation) was achieved by sodium deoxycholate, sodium dodecyl sulfate, or Triton X-100. The degree of enzyme masking was less in vegetative cell membrane fragments than in membranes prepared from stationary-phase or sporulating cells. Results indicate the development of a membrane-bound electron transport system inB. cereusby the end of growth and prior to sporulation, which results in an increased masking of a number of enzymes associated with the terminal respiratory system of the cell.
Relatedness Among
Rhizobium
and
Agrobacterium
Species Determined by Three Methods of Nucleic Acid Hybridization
Authors: Gibbins Ann M. , Gregory K. F.
Published: January 2020

Deoxyribonucleic acid (DNA) was isolated from 20 strains of
Rhizobium
and
Agrobacterium
and from one strain of
Serratia marcescens
; the guanine plus cytosine content of each DNA sample was determined by thermal denaturation. Radioactive DNA was isolated from three reference strains following the uptake of [2-
14
C
]thymidine in the presence of deoxyadenosine. Ribonucleic acid (RNA) polymerase was used to synthesize radioactive RNA on DNA templates from the three reference strains. Radioactive DNA and RNA from the three reference strains were each hybridized with filter-bound DNA from all of the 21 test strains in 6 × SSC (standard saline citrate) and 50% formamide at 43 C for 40 hr. DNA/DNA relatedness was also determined by spectrophotometric measurement of the rates of association of single-stranded DNA. The order of relatedness between strains was similar by each method. Overall standard deviations for the DNA/DNA and DNA/RNA membrane filter techniques were ±0.87 and ±1.03%, respectively; that for the spectrophotometric technique was ±4.11%. The DNA/DNA membrane technique gave higher absolute values of hybridization than did the DNA/RNA technique.
R. leguminosarum
and
R. trifolii
could not be distinguished from each other by these techniques. These results also indicated close relationships between
R. lupini
and
R. japonicum
, and (with less certainty) between
R. meliloti
and
R. phaseoli
. Of all the rhizobia tested against the
A. tumefaciens
371 reference strain, the
R. japonicum
strains were the most unrelated. The three
Agrobacterium
strains used were as related to the
R. lupini
and
R. leguminosarum
references as were several rhizobium strains.
Accumulation of 70
S
Monoribosomes in
Escherichia coli
After Energy Source Shift-Down
Authors: Ruscetti Francis W. , Jacobson Lewis A.
Published: January 2020

When
Escherichia coli
is shifted from glucose-minimal to succinate-minimal medium, a transient inhibition of protein synthesis and a time-dependent redistribution of ribosomes from polysomes to 70
S
monosomes occurs. These processes are reversed by a shift-up with glucose. In a lysate made from a mixture of log-phase and down-shifted cells, the 70
S
monosomes are derived solely from the down-shifted cells and are therefore not produced by polysome breakage during preparation. This conclusion is supported by the absence of nascent proteins from the 70
S
peak. The monosomes are not dissociated by NaCl or by a crude ribosome dissociation factor, so they behave as “complexed” rather than “free” particles. When down-shifted cells are incubated with rifampin to block ribonucleic acid (RNA) synthesis, the 70
S
monosomes disappear with a half-life of 15 min. When glucose is also added this half-life decreases to 3 min. The 70
S
particles are stable in the presence of rifampin when chloramphenicol is added to block protein synthesis. We interpret these data to mean that the existence of the 70
S
monosomes depends on the continued synthesis of messenger RNA and their conversion to free ribosomes (which dissociate under our conditions) is a result of their participation in protein synthesis. Finally, a significant fraction of the RNA labeled during a brief pulse of
3
H-uracil is found associated with the 70
S
peak. These results are consistent with the hypothesis that the 70
S
monosomes are initiation complexes of single ribosomes and messenger RNA, which do not initiate polypeptide synthesis during a shift-down.
Ultrastructural Analysis of Sporulation in a Conditional Serine Protease Mutant of
Bacillus subtilis
Authors: Santo Leatrice , Leighton Terrance J. , Doi Roy H.
Published: January 2020

The morphological characteristics of wild-type
Bacillus subtilis
and a temperature-sensitive serine protease derivative have been observed during vegetative and sporulation time periods. At 30 C wild-type and mutant cells grow and sporulate identically. At 47.5 C wild-type and mutant cells grow identically, but the mutant cells are blocked at stage 0 or I in the sporulation sequence. Wild-type cells sporulate normally at 47.5 C.
Morphology and Ultrastructure of Human T-Mycoplasmas
Authors: Black F. T. , Birch-Andersen A. , Freundt E. A.
Published: January 2020

Four serologically distinct human T-mycoplasmas grown in liquid medium were studied in the electron microscope after ultrathin sectioning and negative staining. The morphology and ultrastructure of these strains was found to be essentially identical to that of other mycoplasmas; i.e., mainly spherical or ovoid cells were observed, but also short rod-shaped cells and filamentous, partly branched forms were noted. The cells were found to be enveloped by a triple-layered membrane, on the outer surface of which an electron-dense layer consisting of radiating hairlike structures was consistently present. In addition to ribosomes, now and then arranged in a regular geometric pattern, the ultrathin sections reveal vacuole-like structures in the interior of the cells.
Regulation of
myo
-Inositol Catabolism in
Aerobacter aerogenes
Authors: Sundaram T. K.
Published: January 2020

A mutant of
Aerobacter aerogenes
produces constitutively the series of enzymes that mediates the degradation of
myo
-inositol and which in the wildtype strain is inducible. When grown on
l
-histidine, the mutant forms the enzymes at a level approximately three times as high as that seen in the induced wild type. The enzymes appear to be coordinately regulated and are sensitive to catabolite repression. Unless repressed, the synthesis of these enzymes markedly retards the growth of the mutant.
Mannitol Sensitivity
Authors: Jensen Pamela , Parkes Charlotte , Berkowitz David
Published: January 2020

The addition of mannitol to cultures of
Salmonella typhimurium
mutants missing mannitol-1-phosphate dehydrogenase causes stasis or lysis. Mannitol-1-phosphate accumulates intracellularly to concentrations of 20 m
m
. The incorporation of acetate into lipid is inhibited before cell wall, protein, or nucleic acid synthesis.
Spore Pool Glutamic Acid as a Metabolite in Germination
Authors: Foerster Harold F.
Published: January 2020

Spore glutamic acid pools were examined in dormant and germinating spores using colorimetric and
14
C analytical procedures. Germination of spores of
Bacillus megaterium
(parent strain), initiated by
d
-glucose, was accompanied by a rapid drop in the level of spore pool glutamate, from 12.0 μg/mg of dry spores to 7.7 μg/mg of dry spores after 30 sec of germination. Similar decreases in extractable spore pool glutamate were observed with
l
-alanine-initiated germination of
B. licheniformis
spores. On the other hand, glutamate pools of mutant spores of
B. megaterium
, with a requirement of γ-aminobutyric acid for spore germination, remained unchanged for 9 min of germination, at which time more than 50% of the spore population had germinated. Evidence for conversion of spore pool glutamate to γ-aminobutyric acid during germination of spores of
B. megaterium
(parent strain) was obtained.
Similarity in the Size and Number of Ribosomal Proteins from Different Prokaryotes
Authors: Sun Tung-Tien , Bickle Thomas A. , Traut Robert R.
Published: January 2020

The ribosomal proteins from nine species of prokaryotes have been compared by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The stained gels were scanned spectrophotometrically, the weight and number average molecular weights were calculated, and the detailed distribution of the proteins as a function of molecular weight was determined. By all of these criteria, the ribosomal proteins from all the species closely resembled each other, despite differences in the pattern of protein bands by conventional disc-gel electrophoresis. Therefore, it is suggested that the structural requirements for the assembly of ribosomal subunits have imposed limitations on the evolution of the ribosomal proteins and that their size has been highly conserved.
Isolation and Some Properties of Cell Envelope Altered Mutants of
Escherichia coli
Authors: Lazdunski Claude , Shapiro Bennett M.
Published: January 2020

Mutants of
Escherichia coli
which have a defect in their permeability barrier were selected. The technique used was to employ a strain of
E. coli
having a deletion in the gene for lactose permease and to select for mutants which can grow on lactose at 40 C. Twenty such mutants were isolated and six of these were found to be more sensitive to actinomycin D, sodium deoxycholate, and sodium dodecyl sulfate than was the parental strain. They were also more sensitive to the antibiotics vancomycin and bacitracin, which inhibit peptidoglycan biosynthesis. These mutants were no more sensitive to several different colicins or phages than was the wild-type strain. One of the mutants selected by this technique has an abnormal morphology when grown on certain carbon sources in minimal medium, and this mutant is more extensively studied in the accompanying paper.
Mutations Affecting the Dissimilation of Mannitol by
Escherichia coli
K-12
Authors: Solomon E. , Lin E. C. C.
Published: January 2020

Mutants of
Escherichia coli
K-12 defective in the mannitol-specific enzyme II complex of the phosphoenolpyruvate phosphotransferase system (PTS) or lacking mannitol-1-phosphate dehydrogenase have been isolated. These mutants fail only to grow on mannitol. Growth of the dehydrogenase-negative mutant on casein hydrolysate can be abruptly inhibited by exposure to mannitol. A mutant with constitutive expression of both of these enzymes has also been isolated. All three mutations are clustered in a region represented at min 71 of the Taylor map. In a mutant with less than 5% of the activity of enzyme I of the PTS, both the enzyme II complex and the dehydrogenase remain inducible by mannitol. In the mutant defective in the enzyme II complex, mannitol is able to induce the dehydrogenase. Thus, mannitol, rather than its phosphorylated product, seems to be the inducer.
A Second Transport System for
l
-Arabinose in
Escherichia coli
B/r Controlled by the
araC
Gene
Authors: Brown Candice E. , Hogg Robert W.
Published: January 2020

Escherichia coli
B/r possesses two active transport systems for
l
-arabinose, both of which are regulated by
araC
, the regulatory gene for the
l
-arabinose operon. The system with the higher affinity for
l
-arabinose has a
K
m
for initial uptake of
l
-arabinose of 8.3 × 10
−6
m
; the system of lower affinity has a
K
m
of 1.0 × 10
−4
m
. The two systems can also be distinguished by differences in their response to analogues that act as competitive inhibitors of initial uptake.
d
-Galactose strongly inhibits
l
-arabinose uptake by the high affinity system but only weakly inhibits such uptake by the low affinity system.
d
-Fucose,
d
-xylose, and β-methyl-
l
-arabinoside competitively inhibit the uptake of
l
-arabinose by both systems to approximately the same extent.
d
-Glucose and
l
-lyxose do not inhibit either system. On the basis of kinetic evidence and the properties of mutants lacking one or the other of the two systems, it has been concluded that the high affinity uptake system involves the
l
-arabinose binding protein. Kinetic studies have shown that the
K
m
for
l
-arabinose uptake by the high affinity system resembles the
K
m
for binding of
l
-arabinose by the binding protein, and both have similar
K
i
values for the inhibitory substrates tested. A consideration of
l
-arabinose transport-deficient mutants has demonstrated that the previously described
araE
mutants lack the low affinity system but retain the high affinity system and have normal levels of the
l
-arabinose binding protein. Mutants described in this communication which lack only the high affinity system either contain no detectable
l
-arabinose binding protein or possess an immunologically cross-reacting material that is reduced in its ability to bind
l
-arabinose. These observations support a role for the binding protein in
l
-arabinose uptake.
Interference-Contrast and Phase-Contrast Microscopy of Sporulation inClostridium thermosaccharolyticumGrown Under Strict Anaerobiosis
Authors: Eller Charles , Ordal Z. John
Published: January 2020

Cells ofClostridium thermosaccharolyticumgrown under strict anaerobiosis (modified Hungate technique) were examined during growth and sporulation by employing Nomarski interference-contrast and Zernike phase-contrast optics to delineate the sequence of morphological changes leading to the formation of free, mature spores. A 0.5%l-arabinose, liquid, complex medium was used to obtain a yield of 30 to 40% free, refractile spores (ca. 108/ml) by 48 hr of incubation. The mean doubling time for the glucose culture (vegetative cells) was found to be 80 min, and that for thel-arabinose culture (sporulating cells), 498 min. By 8 hr of incubation, beginning spore formation became evident in the arabinose culture by the development of a distinct arrowhead-shaped terminal swelling. By 32 hr of incubation or shortly thereafter, Nomarski optics showed the mature spore to be uniformly spherical, whereas the enlarged terminal swelling containing it was not. The use of phase-contrast and interference-contrast optics permitted the characterization of the distinctive morphological changes occurring during sporulation ofC. thermosaccharolyticum.
Selective Inhibition of Deoxyribonucleic Acid Synthesis by 2-Deoxyadenosine in the Blue-Green Bacterium
Agmenellum quadruplicatum
Authors: Ingram L. O. , Fisher W. D.
Published: January 2020

Concentrations of deoxyadenosine which have little effect on net ribonucleic acid (RNA) synthesis or on increase in cell mass selectively inhibit deoxyribonucleic acid (DNA) synthesis in
Agmenellum quadruplicatum
. Exogenously supplied deoxyadenosine, at concentrations above 10 μg/ml, stimulates DNA degradation. These results are correlated with a rapid loss in viability. Over a narrow concentration range (6–15 μg/ml), deoxyadenosine impairs the division process and induces the formation of elongated cells. Low exogenous concentrations of deoxyadenosine are readily incorporated into both DNA and RNA, with the major portion as DNA.
Effect of Deoxyribonucleic Acid Ligands on Deoxyribonucleases and Deoxyribonucleic Acid Polymerase I of
Escherichia coli
K-12
Authors: Eberhard Carolyn , Herrmann Robert L.
Published: January 2020

Endonuclease I, exonuclease I, and exonuclease II-deoxyribonucleic acid (DNA) polymerase I activities are not vital functions in
Escherichia coli
, although the latter two enzymes have been indirectly shown to be involved in DNA repair processes. Acridines such as acridine orange and proflavine interfere with repair in vivo, and we find that such compounds inhibit the in vitro activity of exonuclease I and DNA polymerase I but stimulate endonuclease I activity and hydrolysis of
p
-nitrophenyl thymidine-5′-phosphate by exonuclease II. Another acridine, 10-methylacridinium chloride, binds strongly to DNA but is relatively inert both in vivo and in vitro. These experiments suggest that acridines affect enzyme activity by interacting with the enzyme directly as well as with DNA. Resulting conformational changes in the DNA-dependent enzymes might explain why similar acridines which form similar DNA complexes have such a wide range of physiological effects. Differential sensitivity of exonuclease I and DNA polymerase I to acridine inhibition relative to other DNA-dependent enzymes may contribute to the acridine sensitivity of DNA repair.
Regulation of the Tryptophan Synthetic Enzymes in
Clostridium butyricum
Authors: Baskerville E. N. , Twarog Robert
Published: January 2020

Experiments concerned with the regulation of the tryptophan synthetic enzymes in anaerobes were carried out with a strain of
Clostridium butyricum
. Enzyme activities for four of the five synthetic reactions were readily detected in wild-type cells grown in minimal medium. The enzymes mediating reactions 3, 4, and 5 were derepressed 4- to 20-fold, and the data suggest that these enzymes are coordinately controlled in this anaerobe. The first enzyme of the pathway, anthranilate synthetase, could be derepressed approximately 90-fold under these conditions, suggesting that this enzyme is semicoordinately controlled. Mutants resistant to 5-methyl tryptophan were isolated, and two of these were selected for further analysis. Both mutants retained high constitutive levels of the tryptophan synthetic enzymes even in the presence of repressing concentrations of tryptophan. The anthranilate synthetase from one mutant was more sensitive to feedback inhibition by tryptophan than the enzyme from wild-type cells. The enzyme from the second mutant was comparatively resistant to feedback inhibition by tryptophan. Neither strain excreted tryptophan into the culture fluid. Tryptophan inhibits anthranilate synthetase from wild-type cells noncompetitively with respect to chorismate and uncompetitively with respect to glutamine. The Michaelis constants calculated for chorismate and glutamine are 7.6 × 10
−5
m
and 6.7 × 10
−5
m
, respectively. The molecular weights of the enzymes estimated by zonal centrifugation in sucrose and by gel filtration ranged from 24,000 to 89,000. With the possible exception of a tryptophan synthetase complex, there was no evidence for the existence of other enzyme aggregates. The data indicate that tryptophan synthesis is regulated by repression control of the relevant enzymes and by feedback inhibition of anthranilate synthetase. That this enzyme system more closely resembles that found in
Bacillus
than that found in enteric bacteria is discussed.
Influence of Macromolecular Biosynthesis on Cellular Autolysis in
Streptococcus faecalis
Authors: Sayare Mitchel , Daneo-Moore Lolita , Shockman Gerald D.
Published: January 2020

The addition of several different antibiotics to growing cultures of
Streptococcus faecalis
, ATCC 9790, was found to inhibit autolysis of cells in sodium phosphate buffer. When added to exponential-phase cultures, mitomycin C (0.4 μg/ml) or phenethyl alcohol (3 mg/ml) inhibited deoxyribonucleic acid synthesis, but did not appreciably affect the rate of cellular autolysis. Addition of chloramphenicol (10 μg/ml), tetracycline (0.5 μg/ml), puromycin (25 μg/ml), or 5-azacytidine (5 μg/ml) to exponential-phase cultures inhibited protein synthesis and profoundly decreased the rate of cellular autolysis. Actinomycin D (0.075 μg/ml) and rifampin (0.01 μg/ml), both inhibitors of ribonucleic acid (RNA) synthesis, also reduced the rate of cellular autolysis. However, the inhibitory effect of actinomycin D and rifampin on cellular autolysis was more closely correlated with their concomitant secondary inhibition of protein synthesis than with the more severe inhibition of RNA synthesis. The dose-dependent inhibition of protein synthesis by 5-azacytidine was quickly diluted out of a growing culture. Reversal of inhibition was accompanied by a disproportionately rapid increase in the ability of cells to autolyze. Thus, inhibition of the ability of cells to autolyze can be most closely related to inhibition of protein synthesis. Furthermore, the rapidity of the response of cellular autolysis to inhibitors of protein synthesis suggests that regulation is exerted at the level of autolytic enzyme activity and not enzyme synthesis.
CO
2
-Fixing Enzymes in a Marine Psychrophile
Authors: Vidal María C. , Cazzulo Juan J.
Published: January 2020

A psychrophilic marine
Pseudomonas
was found to contain phosphoenolpyruvate (PEP) carboxylase and an adenosine triphosphate-linked PEP carboxykinase. Some properties of these CO
2
-fixing enzymes were compared with those homologous enzymes from the terrestrial mesophile
Enterobacter cloacae
. The PEP carboxylases from both organisms were activated by acetyl-coenzyme A (CoA) and inhibited by
l
-aspartate. The enzyme from
Pseudomonas
was less dependent on the presence of the activator, but maximal activation was attained at acetyl-CoA concentrations much lower (50 μ
m
) than those required to saturate the enzyme from
E. cloacae
. In both cases the main effect of acetyl-CoA was to decrease the
K
m
value for PEP. The activity of PEP carboxylase from
Pseudomonas
was only slightly inhibited by NaCl, KCl, or NH
4
Cl up to 100 m
m
, whereas the enzyme from
E. cloacae
was inhibited by about 70% under similar experimental conditions. Both PEP carboxylase and PEP carboxykinase from
Pseudomonas
showed considerably lower thermal stability than their counterparts from
E. cloacae
. Our results suggest that the CO
2
-fixing enzymes from a marine
Pseudomonas
and
E. cloacae
are similar in nature and regulation, but they differ in properties related to the peculiar conditions of the marine environment.
Phosphotransacetylase from
Clostridium acidiurici
Authors: Robinson James R. , Sagers Richard D.
Published: January 2020

The phosphotransacetylase from
Clostridium acidiurici
has two properties not observed for this enzyme in other bacteria: (i) it requires a divalent metal for activity, and (ii) it is not subject to uncoupling by arsenate. The enzyme has been obtained in highly purified form, with a specific activity 500-fold higher than crude extracts. Ferrous or manganous ions are required for maximal activity, with Mn
2+
being 50 to 75% as effective as Fe
2+
. The acetyl group can be transferred from acetyl phosphate to coenzyme A in 20 m
m
arsenate without a net decrease in high-energy acyl linkages. Likewise, H
32
PO
4
2−
will exchange with acetyl-PO
4
2−
in the presence of arsenate without loss of acetyl phosphate. This suggests that the active site on the enzyme is capable of discriminating between phosphate and arsenate while permitting the reversible transfer of acyl groups between CoA and phosphate.
Partial Purification and Characterization of
S
-Adenosylhomocysteine Hydrolase Isolated from
Saccharomyces cerevisiae
Authors: Knudsen Richard C. , Yall Irving
Published: January 2020

S
-Adenosylhomocysteine (SAH) hydrolase was purified 25-fold from bakers' yeast by chemical methods and column chromatography. The purified enzyme could readily synthesize SAH from adenosine and homocysteine, but could hydrolyze only negligible amounts of SAH. The purified enzyme showed no activity towards
S
-adenosylmethionine, methylthioadenosine, or adenosine. Several nucleotides, sulfhydryl compounds, and ribose could not replace adenosine or homocysteine in the reaction mixture. SAH could be hydrolyzed by SAH hydrolase if commercial adenosine deaminase was included in the reaction mixture. Under these conditions
l
-homocysteine could act as a product inhibitor. A number of compounds structurally similar to adenosine and homocysteine were found to inhibit synthesis of SAH from adenosine and homocysteine. The strongest inhibitors were adenine, adenosine-3′-monophosphate, adenosine-2′-monophosphate, adenosine diphosphate, adenosine triphosphate, and adenosine-5′-monophosphate. The biosynthetic and hydrolytic activity of SAH hydrolase in yeast cell ghosts was similar to the activity of the enzyme in vitro.
Transfer Among
Erwinia
spp. and Other Enterobacteria of Antibiotic Resistance Carried on R Factors
Authors: Chatterjee Arun K. , Starr Mortimer P.
Published: January 2020

Antibiotic resistance carried on R factors was transferred by conjugation from
Escherichia coli
B/r and
Shigella flexneri
1a to
Erwinia
spp. Tetracycline resistance (TetR) carried on R factor R100
drd-56
was transferred from
E. coli
B/r to strains of
Erwinia amylovora, E. aroideae, E. atroseptica, E. chrysanthemi, E. cytolytica, E. dissolvens, E. herbicola, E. nigrifluens
, and
E. nimipressuralis
, but not to strains of
Erwinia carotovora, E. carnegieana, E. dieffenbachiae, E. oleraceae
, and
E. quercina
. Multiple antibiotic resistance (chloramphenicol, streptomycin, tetracycline; ChlR-StrR-TetR) carried on R factor SR1 was transferred from a clinical isolate of
S. flexneri
1a to strains of
E. aroideae, E. chrysanthemi, E. herbicola
, and
E. nigrifluens
, but not to strains of other
Erwinia
spp. The frequency of this transfer was low with receptive cultures of
Erwinia
spp. and
E. coli
(F
−
strain). Antibiotic resistance in the exconjugants showed varying degrees of stability in the presence or absence of acridine orange, depending on the strain tested. The frequencies of segregation to drug susceptibility in the presence of acridine orange, though low, suggest that the elements exist as plasmids in the majority of the
Erwinia
exconjugants. Multiple antibiotic resistance (ChlR-StrR-TetR) was found to segregate into various resistance classes (ChlR-StrR, StrR-TetR, TetR, StrR, and none) in these exconjugants. The exconjugants of
E. amylovora, E. herbicola
, and
E. nigrifluens
, to which R100
drd-56
was transferred from
E. coli
B/r, were sensitive to the male (F)-specific phage M13. There was a positive correlation between the susceptibility of exconjugants to the F-specific phage M13 and their ability to transfer R100
drd-56
to the recipient cultures of
Escherichia coli, Erwinia herbicola, Salmonella typhimurium
, and
Shigella dysenteriae
. Exceptions were, however, noted with
Erwinia dissolvens
and
E. nimipressuralis
exconjugants harboring R100
drd-56
; these exconjugants, although not susceptible to M13, transferred R100
drd-56
to the recipient cultures. The frequency of transfer of R100
drd-56
and the levels of resistance to tetracycline in
Erwinia
exconjugants were found to differ markedly depending upon the strain employed. Transfer of multiple antibiotic resistance (ChlR-StrR-TetR) from
Erwinia
exconjugants was not obtained in preliminary trials with an
E. coli
F
−
strain as the recipient culture.
Changes in Esters of Fatty Acids of
Rhizopus arrhizus
During Germination and Growth
Authors: Hess S. L. , Weber D. J. , Gunasekaran M.
Published: January 2020

Natural esters of fatty acids of
Rhizopus arrhizus
Fischer increased during the first 48 hr of growth. During the 48- to 72-hr period, there was a shift in concentration from the methyl esters to the ethyl esters of fatty acids.
Difference Between Manganese Ion Requirements of Pediococci and Enterococci
Authors: Efthymiou Constantine J. , Joseph Sam W.
Published: January 2020

For maximal turbidity and dissimilatory activity, three strains of pediococci required the addition of Mn
2+
to Rogosa basal medium. Twenty-two strains of enterococci proved indifferent to this supplement.
Fatty Acid Composition of
Spirochaeta stenostrepta
Authors: Joseph Ronald
Published: January 2020

The fatty acid composition of
Spirochaeta stenostrepta
consists primarily of saturated, branch-chained fatty acids. Iso-C
15
, anteiso-C
15
, iso-C
17
, and anteiso-C
17
represent 66% of the total fatty acids.
Spore Germination of
Bacillus megaterium
QM B1551 Mutants
Authors: Vary J. C.
Published: January 2020

Auxotrophic or antibiotic-resistant mutants of
Bacillus megaterium
QM B1551 are capable of initiation of germination similar to the parental (QM B1551) prototrophic strain.
Toxicity of Irradiated Medium for Repair-Deficient Strains of
Escherichia coli
Authors: Webb Robert B. , Lorenz John R.
Published: January 2020

Nutrient agar medium is made highly toxic to certain repair-deficient strains of
Escherichia coli
by exposure of the uninoculated plates to radiation from cool-white fluorescent lamps or black-light fluorescent lamps. This sensitivity is associated with the genetic deficiencies,
fil, phr
, and
recA
. Repair-sufficient and
uvr
strains are only slightly affected by the irradiated media. The poor growth and reduced plating efficiency frequently associated with BPhr and
recA
strains are very likely caused by inadvertent exposure of the medium to fluorescent light.
Effect of Cultural Conditions on the Fatty Acid Composition of
Thiobacillus novellus
Authors: Levin Richard A.
Published: January 2020

The fatty acid content of
Thiobacillus novellus
was determined under various cultural conditions. Four fatty acids, C
16:0
, C
18:0
, C
18:1
, and a C
19
cyclopropane acid (C
19:cyc
), generally accounted for 90 to 99% of the total acids. Phosphate concentration, temperature, culture agitation, and the presence of branch-chain precursors had no significant effect on cellular fatty acids. Autotrophically grown cells contained more saturated C
16
and C
18
acids than did heterotrophic ones, and the sum of the percentages of the C
18:1
and the C
19:cyc
acids was consistently higher in the heterotrophs. When the inorganic medium was supplemented with biotin, autotrophic cells produced more C
19:cyc
and much less C
18:1
than did autotrophs in unsupplemented medium. Heterotrophic cells grown with biotin also showed a marked reduction of the unsaturated acid and an increase in the cyclopropane acid, except when glutamatecitrate medium was employed, in which case the opposite effect was noted. Two different biotin-supplemented media yielded cells with 75 to 77% of the total fatty acids being the C
19
cyclopropane acid, one of the highest reported values for this class of acid.
Mutant of
Escherichia coli
with Thermosensitive Protein in the Process of Cellular Division
Authors: Nagai Kazuo , Tamura Gakuzo
Published: January 2020

A new thermosensitive mutant of
Escherichia coli
deficient in cell division was isolated by means of membrane filtration after nitrosoguanidine mutagenesis. The mutant cells grow normally at 30 C but stop dividing immediately after shift to 42 C, resulting in multinucleated filaments lacking septa. The number of colony-forming units does not decrease for at least 6 hr at 42 C. The maximum length of the filaments is 10 to 16 times that of normal cells. Addition of a high concentration of NaCl fails to stimulate cell division at 42 C. The filaments formed at 42 C divide abruptly 30 min after shift to 30 C, and synchronous increase of cell number is shown for 3 hr. The macromolecular synthesis of protein and nucleic acids at 42 C is normal on the whole. The cell division shown after the shift from 42 to 30 C is observed in the absence of thymine, but not in the presence of chloramphenicol or in a medium deficient in amino acids. However, the filament can divide to some extent in the presence of chloramphenicol if some protein synthesis is allowed to proceed at 30 C before the addition of the antibiotic. The elongated cells divide at 42 C provided that they are exposed to 30 C before being shifted to high temperature.
Spontaneous Auxotrophic and Pigmented Mutants Occurring at High Frequency in
Bacillus pumilus
NRRL B-3275
Authors: Lovett Paul S.
Published: January 2020

Broth cultures of
Bacillus pumilus
NRRL B-3275 (BpB1) grown at 25, 30, or 37 C contain 1 to 2% spontaneous auxotrophic mutants in both the exponential and stationary phases of growth. Of 70 such mutants isolated from cultures grown at 37 C, approximately two-thirds reverted at such a high frequency as to preclude their study. Of the remaining 22 mutants, 18 required a single amino acid, 1 required adenine, and 1 required uracil. Two of the auxotrophs each required two unrelated amino acids resulting from two independent mutations. All of the mutations reverted spontaneously. Enhanced reversion of approximately one-third of the mutations was obtained with nitrosoguanidine, ethyl methane sulfonate, or diethyl sulfate, or with more than one of these mutagens. The reversion of one mutation was enhanced by 2-aminopurine. The reversion of the remaining mutations was not enhanced by the above mutagens, nor by mutagens known to induce (and revert) frameshift mutations in other bacterial systems. Nine of 10 mutants examined did not show a selective growth advantage over the parents. All but three of the mutations could be linked by PBS1 transduction to one of the previously described auxotrophic markers in strain BpB1. No evidence was obtained for clustering of the mutations on the BpB1 genome. Six of the mutations conferred a requirement for serine. One linked by transduction to
trp-2
, three linked to
argA1
, and two (
ser-2, -3
) linked to
argO1
. Pigmented mutants (containing a carotenoid-like pigment), which occur spontaneously in BpB1 cultures at a frequency on the order of 1 to 5 mutants per 10
4
cells, link by transduction to
ser-2, -3
. Spontaneous mutants of strain BpB1 resistant to rifampin, streptomycin, erythromycin, 5-fluorouracil, or 5-methyltryptophan occur at a frequency similar to that of strains of
B. pumilus
which do not exhibit a high rate of spontaneous mutation to auxotrophy. It is suggested that certain sites or regions of the BpB1 genome exhibit a high rate of spontaneous mutation.
Flagellar Assembly Mutants inEscherichia coli
Authors: Silverman Michael R. , Simon Melvin I.
Published: January 2020

Genetic and biochemical analysis of mutants defective in the synthesis of flagella inEscherichia colirevealed an unusual class of mutants. These mutants were found to produce short, curly, flagella-like filaments with low amplitude (∼0.06 μm). The filaments were connected to characteristic flagellar basal caps and extended for 1 to 2 μm from the bacterial surface. The mutations in these strains were all members of one complementation group, group E, which is located betweenhisanduvrC. The structural, serological, and chemical properties of the filament derived from the mutants closely resemble those of the flagellar hook structure. On the basis of these properties, it is suggested that these filaments are “polyhooks”, i.e., repeated end-to-end polymers of the hook portion of the flagellum. Polyhooks are presumed to be the result of a defective cistron which normally functions to control the length of the hook region of the flagellum.
Temperature-Sensitive Mutation in Regulation of Ribonucleic Acid Synthesis in
Escherichia coli
Authors: Kuwano Michihiko , Endo Hideya , Yamamoto Mikio
Published: January 2020

An
Escherichia coli
mutant dependent on exogenous transfer ribonucleic acid (RNA) for bulk RNA formation at 42 C has been isolated, starting from a parental strain permeable to RNA. In the absence of added transfer RNA at the high temperature, protein synthesis stopped, and the strain formed little if any ribosomal RNA.
Effect of Elevated Temperatures on Protein Synthesis in
Escherichia coli
Authors: Patterson David , Gillespie David
Published: January 2020

Upon a temperature shift from 30 C to 42 to 44 C,
Escherichia coli
experiences a transient slowdown in rate of optical density increase, uridine incorporation, and amino acid incorporation. The data show that the primary target for thermal inactivation is a molecule(s) required for the initiation of protein synthesis. The effect on ribonucleic acid synthesis is a secondary effect.
Localization of Phosphoglucose Isomerase in
Escherichia coli
and Its Relation to the Induction of the Hexose Phosphate Transport System
Authors: Friedberg Ilan
Published: January 2020

The localization of phosphoglucose isomerase (PGI) was studied in relation to the induction of hexose phosphate uptake in
Escherichia coli
. The uptake system is induced only by extracellular glucose-6-phosphate (G6P); there is no induction by intracellular G6P. Fructose-6-phosphate (F6P) is an indirect inducer, and isomerization of F6P to G6P must occur before induction. PGI has been considered to be an internal enzyme; therefore, uptake of F6P by noninduced cells and leakage of the G6P formed would be required for induction. In this study, it was concluded that part of the PGI activity is located in the cell surface because: (i) uninduced, intact cells are able to convert F6P to G6P, whereas the activity of G6P dehydrogenase is not detectable; (ii) when cells are subjected to osmotic shock, about 10% of the PGI activity is found in the shock fluid; and (iii) sorbitol-6-phosphate (S6P) inhibits both PGI activity of whole cells and the induction of hexose phosphate transport system by F6P. S6P was not taken by intact cells. The data indicate that the isomerization of F6P to G6P can take place on the cell surface, and this explains the indirect induction of hexose phosphate transport by F6P.
Growth, Cell Division, and Fragmentation in a Species of
Flexibacter
Authors: Poos Jocelyn C. , Turner F. Rudolf , White David , Simon Gary D. , Bacon Karen , Russell Carl T.
Published: January 2020

Flexibacter
FS-1, a gram-negative gliding bacterium was grown in liquid culture as long (over 100-μm) filaments. The filaments possessed a triple-track wall which resembled that found in other gram-negative bacteria. Although phase-contrast microscopy indicated that the long filaments were nonseptate, electron microscopy revealed three or four septa along the length of each filament. The septa contained lysozyme-sensitive, electron-opaque material, presumed to be peptidoglycan, sandwiched between cell membranes. The outer triple track wall was not part of the septum. Mesosomes were seen in various areas of the cell and frequently were observed attached to septa in different stages of completion. Studies of the organism in slide culture revealed that individual filaments grew in an exponential fashion and divided in the middle despite the long length and multiseptate condition. When the temperature of a liquid culture growing exponentially with a generation time of 90 minutes was shifted from 30 to 35 C, the filaments fragmented into three or four shorter cells within 120 min. The short cells continued to grow exponentially at 35 C at approximately the same rate as at 30 C. When the culture was shifted back to 30 C, the cells immediately stopped dividing and began to elongate. After a period of 2 to 3 hr, cell division resumed. It is suggested that the shift-up in temperature induced the completion of the cross wall (centripetal growth of the triple-track wall) and cell separation at the sites of previously formed septa, whereas the shift-down in temperature caused a transient inhibition of cross-wall formation but not of growth. Fragmentation was inhibited by sodium azide but took place despite the inhibition of protein synthesis by chloramphenicol or the inhibition of deoxyribonucleic acid synthesis by mitomycin C.
Relation Between Protein Synthesis and Phospholipid Synthesis and Turnover in
Escherichia coli
Authors: Crowfoot Peter D. , Esfahani Mojtaba , Wakil Salih J.
Published: January 2020

Turnover of phospholipids occurred continuously in a fatty acid auxotroph of
Escherichia coli
, but in the wild-type parent strain significant turnover occurred only under conditions where protein synthesis was inhibited but lipid synthesis continued. Both strains gave a stringent response of ribonucleic acid accumulation to amino acid starvation, but only in the wild type was lipid synthesis also inhibited. A revertant strain of the auxotroph resembled the wild type in this respect. The phospholipid that accumulates in the culture medium as a result of the lipid turnover appears to be part of a loosely bound low-density complex arising from the cell envelope.
Deoxyribonucleic Acid Replication and Cell Division in
Escherichia coli
at 33 C
Authors: Marunouchi Tohru , Messer Walter
Published: January 2020

At 33 C (60-min generation time) the time required to replicate the chromosome is C = 60 min. The time between the end of a round of replication and cell division is D = 20 min, as at 37 C. Nalidixic acid and a temperature shift in a
dnaB
mutant give identical results for the determination of the end of a round of replication.
Genetic Analysis of Flagellar Mutants inEscherichia coli
Authors: Silverman M. , Simon M.
Published: January 2020

Flagellar mutants inEscherichia coliwere obtained by selection for resistance to the flagellotropic phage χ. F elements covering various regions of theE. coligenome were then constructed, and, on the basis of the ability of these elements to restore flagellar function, the mutations were assigned to three regions of theE. colichromosome. Region I is betweentrpandgal;region II is betweenuvrCandaroD;and region III is betweenhisanduvrC. F elements carrying flagellar mutations were constructed. Stable merodiploid strains with a flagellar defect on the exogenote and another on the endogenote were then prepared. These merodiploids yielded information on the complementation behavior of mutations in a given region. Region III was shown to include at least six cistrons,A, B, C, D, E, andF. Region II was shown to include at least four cistrons,G, H, I, andJ. Examination of the phenotypes of the mutants revealed that those with lesions in cistronEof region III produce “polyhooks” and lesions in cistronFof region III result in loss of ability to produce flagellin. Mutants with lesions in cistronJof region II were entirely paralyzed (mot) mutants. Genetic analysis of flagellar mutations in region III suggested that the mutations located in cistronsA, B, C, andEare closely linked and mutations in cistronsDandFare closely linked.
Betaine-Homocysteine Transmethylase in
Pseudomonas denitrificans
, a Vitamin B
12
Overproducer
Authors: White Raymond F. , Kaplan Louis , Birnbaum Jerome
Published: January 2020

A pantothenate-methionine auxotroph (J741) of
Pseudomonas denitrificans
was isolated whose growth requirement for methionine could not be satisfied by known precursors of the amino acid, including homocysteine. However, some “methyl rich” compounds such as betaine and dimethylacetothetin (DMT) could satisfy the requirement.
S
-Methyl-methionine and
S
-adenosylmethionine were ineffective. Extracts were found to contain an enzyme, betaine-homocysteine transmethylase (BHTase), that uses betaine or DMT as a methyl donor and homocysteine as an acceptor to produce methionine. Growth of J741 in methionine leads to a total repression of the BHTase, whereas the use of DMT leads to a three- to sixfold stimulation of enzyme synthesis compared to betaine-grown cells. The pantothenate requirement is unrelated to the methionine auxotrophy, since the growth of other single auxotrophic mutants as well as revertants of J741 still have their methionine requirement satisfied by betaine or DMT. Another methionine auxotroph that could not use betaine for growth was devoid of BHTase activity.
Thymineless Death and Ultraviolet Sensitivity in
Micrococcus radiodurans
Authors: Little J. G. , Hanawalt P. C.
Published: January 2020

Thymine-requiring mutants of
Micrococcus radiodurans
have been isolated by selection on solid medium containing trimethoprim. Strains requiring either high concentrations of thymine (50 μg/ml) or low concentrations (2 μg/ml) for normal growth were obtained. The Thy
−
mutant requiring low thymine concentrations has been characterized. It was shown to retain the high ultraviolet light (UV) resistance typical of wild-type
M. radiodurans
, but it was not resistant to thymineless death. Preliminary exposure of the cells to thymineless conditions resulted in enhanced UV sensitivity, and this interaction occurred under conditions where “unbalanced growth” was inhibited by the addition of chloramphenicol. Upon addition of thymine to deprived cells, UV resistance was gradually restored, and this recovery took place in the absence of protein synthesis. A model is proposed to account for the similarity of thymineless death in bacteria whose deoxyribonucleic acid repair efficiencies differ widely.
Growth and Macromolecular Composition of a Mutant of
Escherichia coli
During Polyamine Limitation
Authors: Morris David R. , Jorstad Caroline M.
Published: January 2020

A mutant of
Escherichia coli
with reduced levels of biosynthetic arginine decarboxylase was isolated which required putrescine or spermidine for optimal growth. The stimulation of growth by putrescine was 1.5- to 3-fold depending upon the culture medium. Specificity studies supported the concept that the requirement was for spermidine or closely related polyamines, or for diamines which could be converted enzymatically to these compounds. The behavior of the macromolecular composition of the polyamine-starved cells appeared abnormal. The ribonucleic acid to protein and deoxyribonucleic acid to cell ratios in the starved cells were both higher than expected on the basis of their growth rate. The stable ribonucleic acid in the polyamine-limited cells appeared to be normal as judged from size distribution and degree of methylation. The relationship of these results to mechanisms for regulation of nucleic acid and protein synthesis in
E. coli
is discussed.
Partial Purification and Some Properties of the Uridine Diphospho-
N
-Acetylglucosamine-Enolpyruvate Reductase from
Staphylococcus epidermidis
Authors: Wickus Gary G. , Rubenstein Peter A. , Warth Alan D. , Strominger Jack L.
Published: January 2020

A method for the partial purification of the uridine diphospho-
N
-acetylglucosamine-enolpyruvate reductase from
Staphylococcus epidermidis
is presented. Some properties of the enzyme, including its dependence on monovalent cation and flavine adenine dinucleotide, are discussed.