bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxygen Toxicity and the Superoxide Dismutase
Authors: Gregory Eugene M. , Fridovich Irwin
Published: January 2020

Oxygen caused an increase in the amount of superoxide dismutase in
Escherichia coli
B but not in
Bacillus subtilis. E. coli
B cells, induced by growth under 100% O
2
, were much more resistant to the lethal effects of 20 atm of O
2
than were cells which contained the low uninduced level of this enzyme. In contrast,
B. subtilis
, which could not respond to O
2
by increasing its content of superoxide dismutase, remained equally sensitive to hyperbaric O
2
whether grown under 100% O
2
or areobically. The catalase in these organisms exhibited a reciprocal response to oxygen. Thus, the catalase of
E. coli
B was not induced by O
2
, whereas that of
B. subtilis
was so induced. These results are consistent with the view that superoxide dismutase is an important component of the defenses of these organisms against the toxicity of oxygen, whereas their catalases are of secondary importance in this respect. The ability of streptonigrin to generate O
2
−
, by a cycle of reduction followed by spontaneous reoxidation, has been verified in vitro. It is further observed that
E. coli
B which contain the high induced level of superoxide dismutase were more resistant to the lethality of this antibiotic, in the presence of oxygen, than were
E. coli
B which contained the low uninduced level of this enzyme. This difference between induced and uninduced cells was eliminated by the removal of O
2
. These results are consistent with the proposal that the enhanced lethality of streptonigrin under aerobic conditions may relate to its in vivo generation of O
2
−
by a cycle of reduction and spontaneous reoxidation. In toto, these observations lend support to the hypothesis that O
2
−
is an important agent of oxygen toxicity and that superoxide dismutase functions to blunt the threat posed by this reactive radical.
Early Events in Development of Streptococcal Competence
Authors: Leonard C. Gomez
Published: January 2020

Appropriately timed use of trypsin, which inactivates competence factor (CF), and chloramphenicol made feasible a separation and characterization of early events in the development of competence in group H streptococci. Step 1 is production of CF, which is inseparable in time from the concomitant release of free CF into the medium. The producing cells, which are noncompetent at the time, also accumulate cell-bound CF (CB-CF) from the onset of CF synthesis. In step 2, the released CF is adsorbed or taken up in a trypsin-insensitive state by the producing cells and is not destroyed as previously suggested. This occurs rapidly in a transformation-supporting (complete) medium. The rapid decline in free CF is concomitant with the rise in CB-CF, and a maximal increase in the latter does not occur in cultures exposed to trypsin, which inactivates any trypsin-accessible CF. The rapid increase in CB-CF (above trypsin-treated levels) leads to step 3, the induction of competence. All of these steps probably require protein synthesis, because each is inhibited by chloramphenicol. The data also indicate that only free CF that is subsequently adsorbed, and which thus leads to maximal levels of trypsin-insensitive CB-CF, is the effective inducer of competence in either CF-producing (Challis) or CF-nonproducing (Wicky) cultures. The processes induced by the newly bound CF are not fully understood, but certain new properties, previously described by others as indicating competence, were measured during the several steps of competence development. Cell aggregation at pH 2 appears to be related to CB-CF and can be shown before this bound CF has induced competence. The ability of cultures to autolyze maximally can be diminished by trypsin treatment of precompetent cells without affecting subsequent competence development as measured by transformation.
Isolation of Outer Membranes with an Ordered Array of Surface Subunits from
Acinetobacter
Authors: Thornley Margaret J. , Glauert Audrey M. , Sleytr U. B.
Published: January 2020

A method has been developed for the isolation of outer membranes from
Acinetobacter
sp. strain MJT/F5/199A. Washed cells were broken in a French press and, after deoxyribonuclease and ribonuclease treatment, removal of intact cells, and four washes in 20 mosmol phosphate buffer, pH 7.4, with centrifugation at 25,000 ×
g
for 10 min, preparations of cell wall fragments from which almost all pieces of plasma membrane had been removed resulted. Treatment of the cell walls with lysozyme and further washing, in the presence of 20 mM MgCl
2
, yielded preparations of outer membranes. Electron microscopy of freeze-etched preparations shows that a regular pattern of subunits is present on the outer surfaces of intact cells. After negative staining, these subunits are visible on isolated walls and outer membranes; they can be removed by brief treatment with papain. In section, the cell wall structure is that typical of gram-negative bacteria, but the subunits are not detectable on the surface of the outer membrane. The outer membrane retains the appearance of a “unit membrane” in the cell wall, isolated outer membrane, and papain-treated outer membrane fractions. Both cell walls and outer membranes contain a high percentage of protein (76 and 84%, respectively) and not more than 5% carbohydrate, of which glucose and galactose are constitutents. The outer membranes of this
Acinetobacter
thus differ in structure and composition from those of bacteria in the
Enterobacteriaceae
.
Membranes of
Bacillus stearothermophilus
: Factors Affecting Protoplast Stability and Thermostability of Alkaline Phosphatase and Reduced Nicotinamide Adenine Dinucleotide Oxidase
Authors: Wisdom Charlene , Welker N. E.
Published: January 2020

Protoplasts of
Bacillus stearothermophilus
NCA 1503-4R are resistant to osmotic rupture and are not sensitive to mechanical manipulation. Protoplast stability is maintained by divalent cations. The thermostability of protoplasts is enhanced when the cells are grown at elevated temperatures. The membrane content of the cell and the protein-to-lipid ratio of the membrane increases as the growth temperature is increased. The membrane-bound nicotinamide adenine dinucleotide (reduced form) oxidase system from cultures grown at 70 C was more thermostable than the same enzyme system from cultures grown at 55 C. Alkaline phosphatase was resistant to thermal inactivation in the intact protoplast. The extent of this protection is dependent on protoplast stability.
Ammonium Regulation in
Aspergillus nidulans
Authors: Pateman J. A. , Kinghorn J. R. , Dunn Etta , Forbes E.
Published: January 2020

l
-Glutamate uptake, thiourea uptake, and methylammonium uptake and the intracellular ammonium concentration were measured in wild-type and mutant cells of
Aspergillus nidulans
held in various concentrations of ammonium and urea. The levels of
l
-glutamate uptake, thiourea uptake, nitrate reductase, and hypoxanthine dehydrogenase activity are determined by the extracellular ammonium concentration. The level of methylammonium uptake is determined by the intracellular ammonium concentration. The uptake and enzyme characteristics of the ammonium-derepressed mutants,
meaA8, meaB6
, DER3,
amrA1, xprD1
, and
gdhA1
, are described. The
gdhA
mutants lack normal nicotinamide adenine dinucleotide phosphate-glutamate dehydrogenase (NADP-GDH) activity and are derepressed with respect to both external and internal ammonium. The other mutant classes are derepressed only with respect to external ammonium. The mutants
meaA8
, DER3,
amrA1
, and
xprD1
have low levels of one or more of the
l
-glutamate, thiourea, and methylammonium uptake systems. A model for ammonium regulation in
A. nidulans
is put forward which suggests: (i) NADP-GDH located in the cell membrane complexes with extracellular ammonium. This first regulatory complex determines the level of
l
-glutamate uptake, thiourea uptake, nitrate reductase, and xanthine dehydrogenase by repression or inhibition, or both. (ii) NADP-GDH also complexes with intracellular ammonium. This second and different form of regulatory complex determines the level of methylammonium uptake by repression or inhibition, or both.
Transport of Tricarboxylic Acids in
Salmonella typhimurium
Authors: Imai Ko , Iijima Teiji , Hasegawa Takezi
Published: January 2020

Salmonella typhimurium
possesses at least three inducible transport systems for the tricarboxylic acids (citric, isocitric,
cis
-aconitic, and tricarballylic). The first system was induced by citrate, isocitrate, or
cis
-aconitate, and transported citric acid and isocitric acid. The second system was also induced by the same acids as in the first system and transported
cis
-aconitic acid. This system required Mg
2+
ions and was stable at pH 8.4 but unstable at pH 7.0. The metal ion was replaced with Sr
2+
or Ca
2+
ions but not with Ba
2+
ions. The third system was induced by tricarballylate and transported citric acid,
cis
-aconitic acid, and tricarballylic acid.
Protection of Nitrogenase in
Azotobacter vinelandii
Authors: Shah Vinod K. , Pate Jack L. , Brill Winston J.
Published: January 2020

The site or sites that protect nitrogenase from O
2
inactivation in vivo are sensitive to sodium azide or 2,4-dinitrophenol. Both components of nitrogenase can be synthesized when oxidative phosphorylation is disrupted.
Metabolism of the Pyridine Nucleotides Involved in Nicotinamide Adenine Dinucleotide Biosynthesis byClostridium butylicum
Authors: Kasârov Luka B. , Moat Albert G.
Published: January 2020

In order to elucidate the mechanism of the accumulation of considerable amounts of free nicotinic acid (NA) in the culture medium ofClostridium butylicum, this organism was investigated with regard to its ability to metabolize nicotinamide adenine dinucleotide (NAD) and its immediate biosynthetic precursors, nicotinic acid mononucleotide (NAMN) and nicotinic acid adenine dinucleotide (deamido-NAD). Cell-free extracts ofC. butylicumwere found to degrade NAMN and deamido-NAD to NA. NAMN, in the presence of adenosine triphosphate (ATP), was converted to deamido-NAD, but only at high concentrations of ATP (20 mM) was significant synthetic activity observed in competition with NAMN degradation. Degradation of both NAMN and deamido-NAD was activated by ATP at concentrations of 5 and 10 mm. Anaerobiosis markedly enhanced the degradation of the nucleotides. The data indicate that the synthesis of NAMN and deamido-NAD prevails over their degradation only in the presence of high concentrations of ATP. NAD was degraded to nicotinamide mononucleotide (NMN) by a pyrophosphatase. Phosphate markedly inhibited both the deamido-NAD and NAD pyrophosphatases. Under anaerobic conditions there was practically no further degradation of NMN to NA, whereas barely measurable amounts of NA were formed under aerobic conditions. All of these observations suggest that, under the given conditions of anaerobiosis and physiological phosphate concentrations, there is very little degradation of NAD to NMN and practically no degradation to NA byC. butylicum. Thus, NAD represents an insignificant source of the NA accumulated in the culture medium. The intermediates in the biosynthetic pathway (NAMN and deamido-NAD) have been shown to be the major source of the NA which is accumulated byC. butylicum.
Molecular Studies of R Factor Compatibility Groups
Authors: Grindley N. D. F. , Humphreys G. O. , Anderson E. S.
Published: January 2020

Molecular studies of R factors of six groups, F
II
, I
1
, I
2
, N, B, and H, defined on the basis of compatibility, support the conclusions drawn from genetic studies. In general, R factors of a given compatibility group are similar in size. Deoxyribonucleic acid (DNA) reassociation occurs freely between members of the same group but is minimal between heterologous groups. An exception to this was found in group H, of which one factor showed minimal homology with the remaining plasmids of the group. A further exception was found with groups I
1
and B, which, although genetically distinct, show between 18 and 28% of DNA homology. Groups I
1
and I
2
are molecularly distinct, despite the fact that they both stimulate the synthesis of I-fimbriae.
Host Cell Growth in the Presence of the Thermosensitive Drug Resistance Factor, Rts1
Authors: DiJoseph C. G. , Bayer M. E. , Kaji A.
Published: January 2020

We have confirmed and extended the observation of Terawaki et al. that the R factor, Rts1, alters the growth of its host at 42 C. In all media tested there was a period during which total cell numbers increased linearly, while viable counts remained constant. During this period the rate of precursor incorporation per cell particle into deoxyribonucleic acid, ribonucleic acid, and protein declined steadily. These patterns were a consequence of the accumulation of increasing numbers of cells which had lost colony-forming ability. A temperature shiftdown experiment showed that the colony formers could, after a lag, go on to divide normally, whereas most of the noncolony formers could not undergo even a limited number of divisions after shiftdown. The number of normal divisions which occurred after shiftup of Rts1 cells to 42 C was medium dependent. In rich medium there were, on the average, two or three doublings; in glucose medium, one; and in glycerol medium, only a fraction of a doubling. Even in glucose medium, however, no increase in viable counts was observed during growth at 42 C if the cells were first starved for glucose for 1 h at 42 C. A temperature shiftdown from 42 C to 27 C during glucose starvation reversed the effect of starvation at 42 C alone. These results are consistent with the hypothesis that the thermosensitive Rts1 component(s) responsible for the host effects is present at permissive temperature, but can undergo a reversible temperature-induced alteration which then interferes with some essential host function. The detrimental effects of this R factor on its host were also reflected in a heightened sensitivity to kanamycin and actinomycin D at 42 C. Electron microscope observations revealed changes in the appearance of the cell membrane. Membranous invaginations were noted at discrete sites in the cell.
Induction Kinetics of the
l
-Arabinose Operon of
Escherichia coli
Authors: Schleif Robert , Hess Winand , Finkelstein Solomon , Ellis D.
Published: January 2020

After addition of
l
-arabinose to growing
Escherichia coli
, the
l
-ribulokinase (EC 2.7.1.16) and
l
-arabinose isomerase (EC 5.3.1.4) first appear at about 0.7 and 1.4 min, respectively. These times are consistent with the distances of the genes from the ribonucleic acid polymerase initiation site in the operon. The kinetics of appearance of these enzymes as well as those of β-galactosidase (EC 3.2.1.23) in the same strain are consistent with a peptide elongation rate of no less than 14 amino acids per second. A measurement of the average peptide elongation rate made by measuring the kinetics of radioactive amino acid appearance in completed polypeptides yielded a rate of about 12 amino acids per s. Convenient assays of the arabinose isomerase and ribulokinase are also given.
Suppression of Ultraviolet Sensitivity in
Escherichia coli uvr502
by the
su58
Missense Suppressor
Authors: Smirnov G. B. , Skavronskaya A. G.
Published: January 2020

Introduction of the
su58
missense suppressor into the chromosome of the
uvr502
mutant, either by mutation or by transduction, results in a marked increase of ultraviolet resistance of the
uvr502
mutant. In the
uvr
+
genetic background, the
su58
suppressor causes some decrease of ultraviolet resistance and marked increase in the spontaneous mutation frequency. The presence of the
su58
suppressor did not decrease the high frequency of spontaneous mutants in the population of the
uvr502
strain. However, the significant increase in spontaneous mutant frequency in the
uvr
+
su58
strain makes the difference between the
uvr502 su58
and the
uvr
+
su58
strains 18 times lower than that between the
uvr502
and the
uvr
+
suppressor-free strains. Since the missense suppressors act at the level of translation, the results suggest that the product of the
uvr
(
502
) gene is a protein.
Effect of Zn
2+
on Bacterial Conjugation: Increase in Ability of F
−
Cells to Form Mating Pairs
Authors: Ou Jonathan T.
Published: January 2020

Incubation of F
−
cells at 37 C with 10
−3
M Zn
2+
before mating was found to increase the ability of F
−
cells to form mating pairs when mated. This increased pair-forming ability is persistent, at least for the duration of mating. The F
−
cells with increased pair-forming ability obtained by the 10
−3
M Zn
2+
treatment can form mating pairs efficiently with males from which F pili were removed or inactivated with 10
−3
M Zn
2+
.
Ultrastructural Studies of Sporulation in a Conditionally Temperature-Sensitive Ribonucleic Acid Polymerase Mutant of
Bacillus subtilis
Authors: Santo Leatrice , Leighton Terrance J. , Doi Roy H.
Published: January 2020

Morphological studies of a conditionally temperature-sensitive ribonucleic acid polymerase mutant of
Bacillus subtilis
have revealed that sporulation is inhibited at stage II when the cells are grown at 47.5 C. Growth and sporulation occur normally at 30 C with the mutant. The mutant grows normally at 47.5 C but is prevented from sporulating at the nonpermissive temperature by an abnormal septation during forespore membrane formation which prevents the subsequent engulfment process (stage III). The mutation affects the normal functioning of ribonucleic acid polymerase at the nonpermissive temperature resulting in abortive sporulation.
Thymineless Death in
polA
+
and
polA
−
Strains of
Escherichia coli
Authors: Berg Claire M. , O'Neill John M.
Published: January 2020

The extreme sensitivity of
polA
−
cells to thymineless death is due, primarily, to the absence of an extended lag prior to the commencement of death. Once thymineless death has commenced, the rate in
polA
−
cells is only slightly faster than in
polA
+
cells.
Phenotypes of Pleiotropic-Negative Sporulation Mutants of
Bacillus subtilis
Authors: Brehm Sylvia P. , Staal Stephen P. , Hoch James A.
Published: January 2020

The phenotypic properties of representatives of the five genetic classes of pleiotropic-negative sporulation mutants have been investigated. Protease production, alkaline and neutral proteases, was curtailed in
spoA
mutants, but the remainder of mutant classes produced both proteases, albeit at reduced levels. The
spoA
and
spoB
mutants plaqued φ2 and φ15 at high efficiency, but the efficiency of plating of these phages on
spoE, spoF
, and
spoH
mutants was drastically reduced. Antibiotic was produced by the
spoH
mutants and to a degree by some
spoF
mutants, but the other classes did not produce detectable activity. The
spoA
mutants were less responsive to catabolite repression of histidase synthesis by glucose than was the wild type. Severe catabolite repression could be induced in
spoA
mutants by amino acid limitation, suggesting that the relaxation of catabolite repression observed is not due to a defect in the mechanism of catabolite repression. Although others have shown a perturbation in cytochrome regulation in
spoA
and
spoB
mutants, the primary dehydrogenases, succinate dehydrogenase and reduced nicotinamide adenine dinucleotide dehydrogenase, leading to these cytochromes are unimpaired in all mutant classes. A comparison of the structural components of cell walls and membranes of
spoA
and the wild type is made. The pleiotropic phenotypes of these mutants are discussed.
Ethidium Bromide-Resistant Mutant of
Bacillus subtilis
Authors: Bishop Paul E. , Brown Lyle R.
Published: January 2020

An ethidium bromide-resistant mutant (EB8) derived from a Marburg strain of
Bacillus subtilis
was found to be conditionally resistant to 10 μg of ethidium bromide per ml. Expression of resistance is complete only during vegetative growth at incubation temperatures above 30 C in complex medium or minimal medium supplemented with Casamino Acids. Strain EB8 is cross-resistant to acriflavine and proflavine. The ethidium bromide resistance marker is co-transduced with
hisA1
at a frequency of 6% and is located to the right of
hisA1
on the
B. subtilis
chromosome as it is usually represented on the map. Incorporation of [
5
-
3
H
] uridine by strain EB8 showed that ribonucleic acid synthesis in both whole cells and protoplasts is ethidium bromide-resistant.
Release and Recovery of Forespores from
Bacillus cereus
Authors: Andreoli Anthony J. , Suehiro Seishi , Sakiyama Donald , Takemoto Jon , Vivanco Edgar , Lara J. C. , Klute Mary C.
Published: January 2020

A method is described which makes possible the release of immature forespores from sporulating cells at specific stages of development, from the completion of stage III through to mature spore formation. With the aid of zonal density gradient centrifugation, the method makes possible the recovery of quantities of forespores ample for biochemical and physical studies. With the capability to examine forespores and some mother cell components independently, we have established that several enzymes associated with the sporulation process are localized in the newly developed forespores. Studies showed that aspartate aminotransferase and alanine aminotransferase are associated with the forespores, whereas
l
-alanine dehydrogenase is found only in the mother cell cytoplasm.
Exosporium and Spore Coat Formation in
Bacillus cereus
T
Authors: Ohye D. F. , Murrell W. G.
Published: January 2020

The exosporium of
Bacillus cereus
T was first observed as a small lamella in the cytoplasm in proximity to the outer forespore membrane (OFSM) near the middle of the sporangium. Serial sections, various staining methods, and enzyme treatments failed to show any connections between the small lamella and the OFSM. The advancing edge of the exosporium moved toward the polar end of the cell until the spore was completely enveloped. The middle coat was formed between the exosporium and the OFSM from a three-layered single plate or “belt,” consisting of two electron-dense layers separated by an electron-transparent layer. This “belt,” usually first observed toward the center of the sporangium, developed without changing thickness or appearance over the surface of the forespore. Between the middle coat and the OFSM, a layer of cytoplasm about 50-nm thick was enclosed by the developing coat; this became the inner coat. Electron-dense material was deposited on the outer surface of the middle coat to form the outer coat.
Reversible Inactivation of Thiaminase I ofBacillus thiaminolyticusby Its Primary Substrate, Thiamine
Authors: Agee C. Coe , Airth R. L.
Published: January 2020

Thiaminase I ofBacillus thiaminolyticusis reversibly inactivated when it is incubated with its primary substrate, thiamine, or with one of several structural analogues of thiamine in the absence of an acceptor base. The inactivation reaction is pH and temperature dependent and is stochiometric with respect to thiamine and thiaminase I concentrations. One molecule of thiamine is cleaved for each molecule of enzyme inactivated. Inactivation is prevented or reversed by sulfhydryl-reducing agents. Active or reactivated thiaminase I migrate as a single band in polyacrylamide electrophoresis gels. Inactive thiaminase I appears to migrate as two separate bands. Active, inactive, and reactivated thiaminase I are immunologically similar. A possible mechanism for the inactivation of thiaminase I by its substrate is discussed.
Kinetic Analysis of the Products of Donor Deoxyribonucleate in Transformed Cells of
Bacillus subtilis
Authors: Davidoff-Abelson R. , Dubnau D.
Published: January 2020

This paper describes the major transmutations of donor deoxyribonucleic acid (DNA) after uptake by competent
Bacillus subtilis
cells. Kinetic experiments confirm that after exposure to competent cells, donor DNA is converted to double-stranded fragments (DSF) which can be isolated as early as 30 s from the beginning of the reaction. At this time, DSF represent the only identifiable product of donor origin. After 1 to 2 min, DSF are converted to deoxyribonuclease-resistant forms, identified as single-stranded DNA fragments (SSF). SSF are intermediates in the transformation process leading to the formation of donor-recipient complex. This component makes its appearance between 2 to 4 min from the beginning of the transformation process. All the donor-recipient complexes found at the end of the reaction can be accounted for quantitatively by the DSF and the SSF found in the initial stages of transformation. A quantitative discussion of the transformation process is included.
Plasmids of
Shigella dysenteriae
Y6R: a Defective Col Factor
Authors: Porter Bruce W. , Kolodner Richard , Warner Robert C.
Published: January 2020

The six plasmids of
Shigella dysenteriae
Y6R were separated by sucrose gradients into five fractions containing deoxyribonucleic acid (DNA), having contour lengths (expressed in units equal to the fraction of the length of the replicative form of φX174), respectively, of 0.29, 0.35, 0.74, 1.08, and a mixture of 5.7 and 7.2. DNA-DNA hybridization on nitrocellulose filters between each of the plasmids and between plasmid-free
S. dysenteriae
Y6R host DNA and plasmids was investigated. There was a high degree of homology between the 0.29- and 0.35-unit plasmids. No significant homology was found between any of the other pairs of plasmids. Homologous DNA to the extent of 2.4 copies of the 1.08-unit plasmid was found in the host genome. Homology between the other plasmids and the host genome is very slight, but appears to be significant. About 0.7 of the 1.08-unit plasmid is homologous to the ColE1 façtor of
Escherichia coli
JC411 (ColE1). This plasmid may be defective ColE1 factor with the immunity function intact, but with a defect in the gene leading to the production of active colicin. Electron microscope examination of heteroduplexes formed between the two smallest plasmids and between the 1.08-unit plasmid and the ColE1 factor yielded independent determinations of the extent of homology in agreement with the values determined by hybridization. In the latter case, two nonhomologous regions of substitution of DNA were detected.
Effects of External Osmolarity on Phospholipid Metabolism in
Escherichia coli
B
Authors: Munro George F. , Bell Carol A.
Published: January 2020

The turnover of total [
32
P]phospholipids in
Escherichia coli
B is shown to be inversely related to the osmolarity of the medium and a reflection of the rates of turnover of the major phospholipid classes, phosphatidylglycerol and phosphatidylethanolamine. External osmolarity also affects the phosphatidylglycerol content of the culture. These results suggest that alterations in the metabolism of membrane phospholipids may be part of the process of adaptation to the external osmotic environment.
Induction of β-Glucosidases in
Neurospora crassa
Authors: Eberhart Bruce M. , Beck Reta S.
Published: January 2020

The induction of β-glucosidases (EC 3.2.1.21) was studied in
Neurospora crassa
. Cellobiase was induced by cellobiose, but other inducers had little effect on this enzyme. Cellobiase activity was very low in all stages of the vegetative life cycle in the absence of di-β-glucoside inducer. Aryl-β-glucosidase was semiconstitutive at late stages of culture growth prior to conidiation. At early stages, aryl-β-glucosidase was induced by cellobiose, laminaribiose, and gentiobiose, and weakly induced by galactose, amino sugars, and aryl-β-glucosides. The induction properties of the β-glucosidases are compared with those of the other disaccharidases of
Neurospora
. The induction of β-glucosidases was inhibited by glucose, 2-deoxy-
d
-glucose, and sodium acetate. Sodium phosphate concentrations between 0.01 and 0.1 M stimulated induction of both enzymes, while concentrations above 0.1 M were inhibitory. The optimal condition for induction of both β-glucosidases was pH 6.0. Cellobiase induction was relatively more inhibited than aryl-β-glucosidase in the range of pH 6.0 to 8.0.
Lethal and Inhibitory Effects of Sodium Chloride on Thermally Stressed
Staphylococcus aureus
Authors: Erwin Daniel G. , Haight Roger D.
Published: January 2020

Iandolo and Ordal used a double-medium technique for the study of thermal injury in
Staphylococcus aureus
. In their system sodium chloride (salt) was used to distinguish the salt-sensitive from the salt-insensitive portions of the viable population remaining after thermal stressing. The data reported here show that nutrient medium containing salt was lethal for cells immediately postinjury and that nutrient medium containing salt was only inhibitory to injured cells if those cells had been incubated for 30 min in nutrient medium, buffered salt, or buffer alone prior to subjection to nutrient medium containing salt. Sodium ion was implicated as the active agent since nutrient media containing potassium chloride or glycerol (osmotic equivalence) produced neither inhibition nor the lethal effect. The inhibitory effect was interpreted as defining an early stage in the thermal injury recovery process.
Reduced Nicotinamide Adenine Dinucleotide Oxidase Activity and H
2
O
2
Formation of
Mycoplasma pneumoniae
Authors: Low Iolanda E. , Zimkus Saundra M.
Published: January 2020

Cell-free extracts of
Mycoplasma pneumoniae
showed two distinct reduced nicotinamide adenine dinucleotide (NADH
2
) oxidase activities in the supernatant fraction. By ammonium sulfate fractionation and polyacrylamide gel electrophoresis, one activity not requiring flavine co-factors was precipitated by 50 to 70% ammonium sulfate concentration and identified with a slower-moving band on acrylamide gel electrophoresis; a second NADH
2
oxidase activity was flavine mononucleotide (FMN) dependent and associated with a more rapidly moving band; it could only be partially precipitated by ammonium sulfate concentrations ranging from 50 to 100%. Studies with alternate electron acceptors indicated the presence of a menadione, a 2,6-dichlorophenol indophenol and a very weak ferricyanide oxido-reductase activity, but no cytochrome
c
oxido-reductase, in the cell-free preparations. The NADH
2
oxidase activities of all fractions were relatively cyanide insensitive and were only minimally inhibited by flavoprotein and other respiratory chain inhibitors. H
2
O
2
formation was negligible unless FMN, but not flavine adenine dinucleotide (FAD), was added to the crude NADH
2
oxidase system; upon fractionation and electrophoresis, the H
2
O
2
formation was associated with the FMN-dependent, more rapidly moving NADH
2
oxidase band. This FMN-dependent NADH
2
oxidase-H
2
O
2
generating system may be a mechanism for the H
2
O
2
formation observed during glucose oxidation in the intact organism.
Utilization of Octopine and Nopaline by
Agrobacterium
Authors: Lippincott James A. , Beiderbeck Rolf , Lippincott Barbara B.
Published: January 2020

Tests for utilization of
d
-octopine and nopaline in defined media containing a carbon and nitrogen source were made on 60 strains of
Agrobacterium
representing four species and on a representative of each of five species of
Rhizobium
. Among 46 virulent strains of
Agrobacterium
, only two strains were found which utilized neither compound, while three strains were found which could utilize both. Of the remaining virulent strains, 27 utilized octopine and 14 utilized nopaline. Each of six strains of
A. rhizogenes
tested utilized only octopine but at a slower rate relative to growth than most
A. tumefaciens
. All eight of the
A. radiobacter
strains failed to utilize either compound, as did four of six nonvirulent strains of
A. tumefaciens
. The rhizobia did not utilize octopine or, with the possible exception of
R. japonicum
, nopaline. Virulence in the genus
Agrobacterium
is concluded to be highly correlated with the ability to utilize one or both of these compounds.
Chemical Analysis of the Outer Membrane and Other Layers of the Cell Envelope of
Acinetobacter
sp
Authors: Thorne Kareen J. I. , Thornley Margaret J. , Glauert Audrey M.
Published: January 2020

Chemical analysis of fractions of the cell envelope of
Acinetobacter
sp. strain MJT/F5/199A, prepared by breakage in the French press and removal of plasma membranes, followed by sequential treatment with lysozyme and with papain, confirmed the existence of layers previously identified by electron microscopy. Outside the plasma membrane and periplasmic space, the envelope is composed of (i) a peptidoglycan-containing dense layer, (ii) an intermediate layer, (iii) a lipopolysaccharide-containing outer membrane, and (iv) an ordered array of protein subunits. A small amount of carbohydrate (3%) is found associated with protein in the fraction containing both the surface subunits and the intermediate layer. The papain-treated outer membranes contain 67% protein, 24% lipid, together with 11% lipopolysaccharide, and about 6% of non-lipopolysaccharide hexosamine. Lipid is located only in the papain-treated outer-membrane and is mainly phospholipid: 29% phosphatidyl glycerol, 30% phosphatidyl ethanolamine, and 40% cardiolipin. The principal fatty acid is C
18:1
. Significant amounts of alcohols
16:1
and alcohols
18:1
, which are found in
Acinetobacter
waxes, were recovered from the outer membrane.
Isolation and Characterization of Cell Wall-Defective Variants of
Bacillus subtilis
and
Bacillus licheniformis
Authors: Wyrick Priscilla B. , Rogers Howard J.
Published: January 2020

Quantitative mass conversion of intact bacterial cells of
Bacillus subtilis
and
B. licheniformis
to L-phase variants has been effected after lysozyme treatment. After subculture of the unstable L-phase variants for several months in the presence of methicillin, stable L-phase variants were obtained which grew in the absence of the antibiotic and were then unable to revert to the classical bacterial phase under conditions which gave rise to mass reversion of the protoplasts and unstable L-variants. These stable L-phase variants, which retained many of the physiological properties of the bacterium from which they were derived, were capable of growing exponentially and multiplying in liquid medium. Their morphology and apparent modes of reproduction were consistent with that described for other L-phase variants. The morphological events, as monitored by the electron microscope, of the reversion to the intact bacterial phase of an unstable L-phase variant of
B. licheniformis
are described.
Evidence for Proteolytic Degradation of Histidinol Phosphate Phosphatase Specified by Nonsense Mutants of the
hisB
Gene of
Salmonella typhimurium
Authors: Houston L. L.
Published: January 2020

The gene products from
hisB
nonsense mutants having histidinol phosphate phosphatase activity were isolated from
Salmonella typhimurium
. The enzyme from strain TR691 (
hisB278 hisT1529 aroD5
) was isolated in the presence of diisopropylfluorophosphate. Three electrophoretically separable forms were demonstrated, and all were shown to have a mol wt of approximately 38,000 and to consist of a single polypeptide chain. Previously, two forms of the phosphatase enzyme from this strain were isolated without diisopropylfluorophosphate and shown to have a different subunit composition. Strain TA387 (
hisB2133 his 01242
) was shown to have two electrophoretically separable phosphatases with a mol wt of about 52,000 and consisted of 17,000- to 19,000-mol wt polypeptide chains as evidenced by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The results could be explained by proteolytic cleavage of the primary gene product which can partially be prevented by the protease inhibitor. Strain TA387 phosphatase lost all activity in 8 M urea but could be renatured by dialysis. Gel filtration showed that it also regained its original molecular weight. The values of

K
m

of histidinol phosphate and the competition inhibition constant for histidinol were determined. The addition of MnCl
2
to the assay was shown to shift the optimal pH value to a lower pH value.
Effect of Isoleucine, Valine, or Leucine Starvation on the Potential for Formation of the Branched-Chain Amino Acid Biosynthetic Enzymes
Authors: Wasmuth John J. , Umbarger H. E.
Published: January 2020

The derepression of the isoleucine and valine biosynthetic enzymes in
Escherichia coli
and
Salmonella typhimurium
was examined under conditions of restriction of isoleucine, valine, or leucine (the three amino acids needed for multivalent repression of these enzymes). A procedure was used that allowed the measurement of enzyme-forming potential that accumulated during the starvation period, but could not be expressed unless the missing amino acid was supplied. The threonine deaminase (the product of the
ilvA
gene)-forming potential that accumulated under such conditions was found to be unstable and decayed with a half-life of about 2.5 min (at 37 C). Evidence was obtained that indicates the threonine deaminase-forming potential that accumulates under conditions of isoleucine starvation is in the form of initiated (rifampin-resistant), but uncompleted (actinomycin D-sensitive), messenger ribonucleic acid chains. Furthermore, it appears that a large portion of the threonine deaminase- and dehydrase (the product of the
ilvD
gene)-forming potential, under such conditions, is in the form of initiated polypeptide chains. Based on these results and results obtained with SuA
−
strains, a model is presented that explains how the second gene (
D
) in the
ilvADE
operon can be partially transcribed and translated under conditions in which there are no completed messenger ribonucleic acids for the gene (
A
) transcribed before it.
Protein and Fatty Acid Composition of Mesosomal Vesicles and Plasma Membranes of
Staphylococcus aureus
Authors: Theodore T. S. , Panos C.
Published: January 2020

Qualitatively, the protein and fatty acid composition of purified mesosomal vesicles and the plasma membrane isolated from
Staphylococcus aureus
ATCC 6538P are identical, the major difference between these two cellular components being only quantitative in nature. Mesosomal vesicles and plasma membranes, when subjected to acidic or neutral disk gel electrophoresis, exhibited more than 22 bands of protein. With urea-acetic acid gels, the plasma membrane had a higher concentration of “slower-migrating proteins” whereas “faster-migrating proteins” predominated in the mesosomal vesicles. With neutral disk gel electrophoresis, mesosomal vesicles exhibited one prominent protein band with an approximate molecular weight of 35,000 and which was four times greater than that found in the corresponding region on gels of the plasma membrane. Finally, fatty acid analyses by capillary column gas chromatography showed that although the fatty acid composition is the same, the fatty acid content in mesosomal vesicles is 48% greater than that of the plasma membrane. The dominant fatty acids in both of these cellular components are the iso and anteiso branched methyl C15, C17, and C19 fatty acids and comprise at least 85% of the total fatty acids extracted. These results show that distinct chemical differences exist between the mesosomal vesicles and the plasma membrane of
Staphylococcus aureus
.
Purification and Properties of Cytoplasmic and Mitochondrial Malate Dehydrogenases of
Physarum polycephalum
Authors: Teague W. Martin , Henney Henry R.
Published: January 2020

Two isoenzymes of malate dehydrogenase (MDH) were demonstrated in plasmodia of
Physarum polycephalum
by polyacrylamide-gel electrophoresis. The more “cathodal” form was uniquely associated with mitochondria (M-MDH) and the other form was found in the soluble cytoplasm (S-MDH). The isoenzymes were separated by acetone fractionation of soluble plasmodial homogenates acidified to pH 5.0. The M-MDH was purified 201-fold by cetylpyridinium chloride treatment, fractionation with ammonium sulfate, gradient elution from sulfoethyl cellulose at pH 6.0, and Sephadex G-100 chromatography. The S-MDH was purified 155-fold by ammonium sulfate fractionation, diethylaminoethyl cellulose chromatography, gradient elution from sulfoethyl cellulose at pH 5.5, and Sephadex G-100 chromatography. The optimal
cis
-oxalacetate concentrations were 0.35 mM for M-MDH and 0.25 mM for S-MDH, and the optimal pH for both isoenzymes was 7.6 for oxalacetate reduction. The optimal
l
-malate concentrations were 5 mM for S-MDH and 6 mM for M-MDH, and both isoenzymes exhibited an optimal pH of 10.0 for L-malate oxidation. The Michaelis constants of S-MDH and M-MDH served to discriminate between the isoenzymes. The S-MDH was more heat-stable than the M-MDH. High concentrations of oxalacetate and malate inhibited S-MDH more than M-MDH. The isoenzymes were further distinguished by their utilization of analogues of nicotinamide adenine dinucleotide. Many properties of the
Physarum
isoenzymes were similar to those of more complex organisms, especially vertebrates.
Camphor Plasmid-Mediated Chromosomal Transfer in
Pseudomonas putida
Authors: Shaham M. , Chakrabarty A. M. , Gunsalus I. C.
Published: January 2020

Camphor-utilizing strains of
Pseudomonas putida
have been shown to carry the genetic information required for camphor degradation on a plasmid. The plasmid-carrying strains can serve as donors of both plasmid-borne and chromosomal genes. As recipients, plasmid-deleted strains are much superior to those carrying the camphor pathway genes. The transfer frequency of chromosomal, but not plasmid-borne, genes is markedly enhanced if the donor cells are irradiated with ultraviolet light followed by 3-h of growth on a rich medium in the dark. Recombinants selected for prototrophy are stable and most acquire the camphor (CAM) plasmid concomitantly; only a few of the Cam
+
recombinants inherit the donor's ability to transfer chromosomal genes at a high frequency. Transfer-defective mutations occur on the CAM plasmid, affecting both CAM and chromosomal gene transfer.
Mutants of
Escherichia coli
K-12 “Cryptic,” or Deficient in 5′-Nucleotidase (Uridine Diphosphate-Sugar Hydrolase) and 3′-Nucleotidase (Cyclic Phosphodiesterase) Activity
Authors: Beacham I. R. , Kahana R. , Levy L. , Yagil E.
Published: January 2020

Mutants of
Escherichia coli
have been selected for the absence of 5′-nucleotidase (uridine diphosphate-sugar hydrolase) and 3′-nucleotidase (2′,3′-cyclic phophodiesterase). Mutants selected for the absence of 5′-nucleotidase are of two kinds: those that lack detectable activity for the enzyme (Ush
−
), and those that possess activity when cell extracts are assayed, but not when intact cells are assayed (cryptic; Crp
−
). The latter class is probably identical to a type of mutant previously reported by Ward and Glaser. When mutants are selected for the absence of 3′-nucleotidase, Crp
−
mutants are also obtained. Thus far, however, mutants totally lacking this enzyme have not been found. The location on the genetic map of one
ush
mutation is at position 11 min and that of one
crp
mutation at approximately 67 min. In the
crp
mutant, 5′-nucleotidase and 3′-nucleotidase remain located in the periplasm. This mutant is also cryptic for alkaline phosphatase but not for acid hexose phosphatase. Treatment of cells with ethylenediamine-tetraacetate substantially alleviated crypticity. These data are discussed in terms of the organization of periplasmic enzymes and of the outer membrane as a permeability barrier.
Conjugal Deoxyribonucleic Acid Replication by
Escherichia coli
K-12: Stimulation in
dnaB
(ts) Donors by Minicells
Authors: Fenwick R. G. , Curtiss Roy
Published: January 2020

R64-11
+
donor cells that are thermosensitive for vegetative DNA replication will synthesize DNA at the restrictive temperature when recipient minicells are present. This is conjugal DNA replication because it is R64-11 DNA that is being synthesized and there is no DNA synthesis if minicells that cannot be recipients of R64-11 DNA are used. The plasmid DNA present in the donor cells before mating is transferred to recipient minicells within the first 20 min of mating, but additional copies of plasmid DNA synthesized during the mating continue to be transferred for at least 90 min. However, the transfer of R64-11 DNA to minicells is not continuous because the plasmid DNA in minicells is the size of one R64-11 molecule or smaller, and there are delays between the rounds of plasmid transfer. DNA is synthesized in minicells during conjugation, but this DNA has a molecular weight much smaller than that of R64-11. Thus, recipient minicells are defective and are not able to complete the synthesis of a DNA strand complementary to the single-stranded R64-11 DNA received from the donor cell.
Determination of the Length of the V Colicinogenic Factor and a Derivative Fertility Factor
Authors: Kahn Phyllis L.
Published: January 2020

Plasmid deoxyribonucleic acid from
Escherichia coli
harboring either the V colicinogenic factor (Col V) or the derivative fertility factor (Fv), (a non-colicin-producing fertility factor derived from Col V) were separated by cesium chloride-ethidium bromide centrifugation and examined by electron microscopy. Results indicate a deletion of 11 μm of deoxyribonucleic acid in the transition from Col V to Fv.
Oxygen Metabolism in
Lactobacillus plantarum
Authors: Gregory Eugene M. , Fridovich Irwin
Published: January 2020

Lactobacillus plantarum
, although able to grow in the presence of oxygen, was found to retain a completely anaerobic metabolism. Thus,
L. plantarum
did not consume detectable amounts of oxygen and did not contain measureable amounts of those enzyme activities which serve to protect anaerobic cells against the lethality of O
2
−
and of H
2
O
2
. Superoxide dismutase, catalase, and peroxidase appeared to be absent from these cells.
L. plantarum
was unusually resistant towards hyperbaric oxygen, indicating that it did not reduce oxygen even when exposed to high concentrations of this gas. A photochemical reaction mixture, known to generate O
2
−
, did kill
L. plantarum
. The lethality was diminished by superoxide dismutase, catalase, or mannitol and was augmented by H
2
O
2
. This suggests that the lethal agent generated in the photochemical system was primarily OH., generated from the reaction of O
2
−
with H
2
O
2
.
Gene Order and Co-Transduction in the
leu-ara-fol-pyrA
Region of the
Salmonella typhimurium
Linkage Map
Authors: Kemper Jost
Published: January 2020

The gene order and orientation in the
leu-pyrA
region of the
Salmonella typhimurium
linkage map was established by phage P22-mediated transductions. The gene order, in counterclockwise orientation, is
leuO-leuA-leuB-leuC-leuD-ara-fol-pyrA
. The
fol
locus is co-transducible with either the
ara
and
leu
loci or the
pyrA
locus, whereas no co-transduction for the
ara
and
pyrA
loci can be found.