bluuebunny/crossref_metadata_2025 huggingface dataset:
Murein Synthesis and Identification of Cell Wall Precursors of Temperature-Sensitive Lysis Mutants of
Escherichia coli
Authors: Lugtenberg E. J. J. , de Haas-Menger Liesbeth , Ruyters W. H. M.
Published: January 2020

A group of temperature-sensitive lysis mutants of
Escherichia coli
K-12 was studied. Mutants impaired in the synthesis of uridine diphosphate-
N
-acetylmuramyl (UDP-MurNAc)-pentapeptide or in the synthesis of murein amino acids were found. Their rate of murein synthesis at the restrictive temperature was decreased. A large number of mutants did not differ from the parent strain with respect to the rate of murein synthesis and the precursor pattern. The behavior of these mutants is discussed. It was impossible to accumulate UDP-MurNAc-pentapeptide in
E. coli
by the antibiotics penicillin and vancomycin. The hypothesis is put forward that the amount of this murein precursor is regulated by feedback inhibition.
Naturally Occurring R Factor, Derepressed for Pilus Synthesis, Belonging to the Same Compatibility Group as the Sex Factor F of
Escherichia coli
K-12
Authors: Dennison Sheena
Published: January 2020

A naturally occurring R factor with constitutive pilus synthesis is described which resembles the sex factor F in compatibility and in restricting coliphage T7. Unlike F, it is not cured during growth with acridine orange. Results suggest that the R factor produces repressor of pilus synthesis, to which the operator is insensitive (
i
+
o
c
). In this respect it differs from both the F factor (
i
−
o
+
) and wild-type F-like R factors (
i
+
o
+
).
Effect of Temperature on the Fatty Acid Composition of the Extreme Thermophiles,Bacillus caldolyticusandBacillus caldotenax
Authors: Weerkamp A. , Heinen W.
Published: January 2020

Gas chromatographic analysis of extracts fromBacillus caldolyticusandBacillus caldotenaxgrown at 60, 70, or 80 C showed that both contain branched-chain fatty acids as major constituents at all temperatures tested. With increasing temperature, a decrease of i-C15 and an increase of i-C17 fatty acids were observed in both strains, as well as a decrease of i-C16 fatty acids corresponding to an increase of n-C16 fatty acids. The most obvious difference was that the shifts observed withB. caldolyticusoccurred mainly upon raising the temperature to 10 C above, and inB. caldotenaxupon lowering the temperature to 20 C below, the optimal growth temperature.
Regulation of the Methionine Feedback-Sensitive Enzyme in Mutants of
Salmonella typhimurium
Authors: Lawrence David A.
Published: January 2020

Assay of the first enzyme unique to methionine biosynthesis, homoserine-
O
-transsuccinylase, in
metJ
and
metK
regulatory mutants of
Salmonella typhimurium
showed that synthesis of the enzyme was derepressed seven- and fourfold, respectively. The possibility of noncoordinate regulation of the methionine enzymes is discussed. In
metA
feedback-resistant mutants, the enzyme activity can be inhibited in vitro by 10 m
m
S
-adenosylmethionine but not by 10 m
m l
-methionine; hence, the synergistic inhibition found for the wild-type enzyme is not effective in these latter mutants.
Glucose Degradation, Molar Growth Yields, and Evidence for Oxidative Phosphorylation in
Streptococcus agalactiae
Authors: Mickelson M. N.
Published: January 2020

In a complex medium with the energy source as the limiting nutrient factor and under anaerobic growth conditions,
Streptococcus agalactiae
fermented 75% of the glucose to lactic acid and the remainder to acetic and formic acids and ethanol. By using the adenosine triphosphate (ATP) yield constant of 10.5, the molar growth yield suggested 2 moles of ATP per mole of glucose from substrate level phosphorylation. Under similar growth conditions, pyruvate was fermented 25% to lactic acid, and the remainder was fermented to acetic and formic acids. The molar growth yield suggested 0.75 mole of ATP per mole of pyruvate from substrate level phosphorylation. Under aerobic growth conditions about 1 mole of oxygen was consumed per mole of glucose; about one-third of the glucose was converted to lactic acid and the remainder to acetic acid, acetoin, and carbon dioxide. Molar growth yields indicated 5 moles of ATP per mole of glucose. Estimates based on products of glucose degradation suggested that about one-half of the ATP was derived from substrate level phosphorylation and one-half from oxidative phosphorylation. Addition of 0.5
m
2,4-dinitrophenol reduced the growth yield to that occurring in the absence of oxygen. Aerobic pyruvate degradation resulted in 30% of the substrate becoming reduced to lactic acid and the remainder being converted to acetic acid and carbon dioxide, with small amounts of formic acid and acetoin. The molar growth yields and products found suggested that 0.70 mole of ATP per mole of pyruvate resulted from substrate level phosphorylation and 0.4 mole per mole of pyruvate resulted from oxidative phosphorylation.
Isolation of Temperature-Sensitive Mutants of
Schizosaccharomyces pombe
Authors: Bonatti Stefania , Simili Marcella , Abbondandolo Angelo
Published: January 2020

Seventy-one mutants of the yeast
Schizosaccharomyces pombe
that were able to grow on complete medium at 25 C but not at 37 C were isolated. Strains selected for further study showed: (i) single gene mutation and (ii) cell lengthening at the restrictive temperature. Preliminary characterization of 13 mutants is reported. Seven of them have a less pronounced synthesis of deoxyribonucleic acid at the restrictive temperature, and four of them seem to be affected in cell division.
Fermentation of Fructose and Synthesis of Acetate from Carbon Dioxide by
Clostridium formicoaceticum
Authors: O'Brien W. E. , Ljungdahl Lars G.
Published: January 2020

Clostridium formicoaceticum
ferments fructose labeled with
14
C in carbon 1, 4, 5, or 6 via the Embden Meyerhof pathway. In fermentations of fructose in the presence of
14
CO
2
, acetate is formed labeled equally in both carbons. Extracts convert the methyl groups of 5-methyltetrahydrofolate and methyl-B
12
to the methyl group of acetate in the presence of pyruvate. Formate dehydrogenase, 10-formyltetrahydrofolate synthetase, 5,10-methenyltetrahydrofolate cyclohydrolase, 5,10-methylenetetrahydrofolate dehydrogenase, and 5,10-methylenetetrahydrofolate reductase are present in extracts of
C. formicoaceticum
. These enzymes are needed for the conversion of CO
2
to 5-methyltetrahydrofolate. It is proposed that acetate is totally synthesized from CO
2
via the reactions catalyzed by the enzymes listed above and that 5-methyltetra-hydrofolate and a methylcorrinoid are intermediates in this synthesis.
Utilization of γ-Aminobutyric Acid as the Sole Carbon and Nitrogen Source by
Escherichia coli
K-12 Mutants
Authors: Dover Shabtay , Halpern Yeheskel S.
Published: January 2020

Wild-type strains of
Escherichia coli
K-12 cannot grow in media with γ-aminobutyrate (GABA) as the sole source of carbon or nitrogen. Mutants were isolated which could utilize GABA as the sole source of nitrogen. These mutants were found to have six- to ninefold higher activities of γ-aminobutyrate-α-ketoglutarate transaminase (EC 2.6.1.19) and succinate semialdehyde dehydrogenase (EC 1.2.1.16) than those of the wild-type parent strains. Secondary mutants derived from these GABA-nitrogen-utilizing strains were able to grow on GABA as the sole source of carbon and nitrogen. They also grew faster on a variety of other carbon and nitrogen sources, and their growth was more strongly inhibited by different metabolic inhibitors than was that of the parent strains. The nature of the two mutations and the possible genes involved are discussed. A scheme of the pathway for GABA breakdown in
E. coli
K-12 is presented.
Chromosome Replication and Cell Division in
Escherichia coli
at Various Temperatures of Growth
Authors: Pierucci O.
Published: January 2020

The effect of temperature on the growth rate and the pattern of chromosome replication during the division cycle of
Escherichia coli
B/r growing in various media was investigated. The time between divisions, the time for a round of replication (C), and the time between completion of a round and cell division (D) were threefold longer at 21 C than at 37 C. At all temperatures and in all media, D equalled one-half C, suggesting that a common mechanism controls chromosome replication and the progression of the cell toward division after completion of a round of replication.
Morphogenesis of Ascospores in
Saccharomyces cerevisiae
Authors: Guth E. , Hashimoto T. , Conti S. F.
Published: January 2020

Ultrastructural changes associated with ascospore formation in
Saccharomyces cerevisiae
were investigated by using freeze-etching and thin-sectioning techniques. The first nuclear division (meiosis I) is indicated by the appearance of spindle fibers within the nucleus. The nucleus subsequently elongates and eventually assumes a barbell shape; the second nuclear division (meiosis II) occurs before nuclear separation. The spindle fibers involved in meiosis II appear to be oriented perpendicular to those observed in meiosis I. A discrete bilaminar structure (forespore wall) progressively delineates each ascospore nucleus and encloses cytoplasmic material including mitochondria and endoplasmic reticulum. The forespores then elongate, close off, and become separated from the ascus cytoplasm by membranes. The ascospores assume a spherical shape as spore coat material is laid down; the latter stages of ascospore formation are characterized by thickening of the ascospore wall and disintegration of the ascus cytoplasm. No structures which could be identified as chromosomes were observed.
Transport Alterations in a Phosphatidylethanolamine-Deficient Mutant of
Bacillus subtilis
Authors: Beebe James L.
Published: January 2020

A mutant of
Bacillus subtilis
ATCC 6051, demonstrated to be deficient in phosphatidylethanolamine, was found to differ from the parent strain in the rate of uptake of a variety of metabolites.
Polynucleotide Sequence Divergence Among Strains ofEscherichia coliand Closely Related Organisms
Authors: Brenner Don J. , Fanning G. R. , Skerman F. J. , Falkow Stanley
Published: January 2020

Polynucleotide sequence similarity tests were carried out to determine the extent of divergence present in a number ofEscherichia colistrains, obtained from diverse human, animal, and laboratory sources, and closely related strains ofShigella, Salmonella, and the Alkalescens-Dispar group. At 60 C, relative reassociation of deoxyribonucleic acid (DNA) from the various strains withE. coliK-12 DNA ranged from 100 to 36%, with the highest level of reassociation found for three strains derived from K-12, and the lowest levels for two “atypical”E. colistrains andS. typhimurium. The change in thermal elution midpoint, which indicates the stability of DNA duplexes, ranged from 0.1 to 14.5 C, with thermal stability closely following the reassociation data. Reassociation experiments performed at 75 C, at which temperature only the more closely related DNA species form stable duplexes, gave similar indications of relatedness. At both temperatures, Alkalescens-Dispar strains showed close relatedness toE. coli, supporting the idea that they should be included in the genusEscherichia. Reciprocal binding experiments withE. coliBB, 02A, and K-12 yielded different reassociation values, suggesting that the genomes of these strains are of different size. The BB genome was calculated to be 9% larger than that of K-12, and that of 02A 9% larger than that of BB. Calculation of genome size for a series ofE. colistrains yielded values ranging from 2.29 × 109to 2.97 × 109daltons.E. colistrains and closely related organisms were compared by Adansonian analysis for their relatedness to a hypothetical median strain.E. coli0128a was the most closely related to this median organism. In general, these data compared well with the data from reassociation experiments amongE. colistrains. However, anomalous results were obtained in the cases ofShigella flexneri, S. typhimurium, and “atypical”E. colistrains.
Deoxyribonucleic Acid Homologies Among SomePseudomonasSpecies
Authors: Palleroni N. J. , Ballard R. W. , Ralston Ericka , Doudoroff M.
Published: January 2020

Phylogenetic relationships among a number of strains belonging to the genusPseudomonaswere explored by the use of in vitro deoxyribonucleic acid (DNA) hybridization. The fluorescent nomenspecies (P. fluorescens, P. putida, P. aeruginosa, P. cichorii, P. syringae, and related species), as well as the nonfluorescent speciesP. stutzeri, P. mendocina, P. alcaligenes, andP. pseudoalcaligenes, were shown to belong to a single DNA homology complex which is isolated from otherPseudomonasspecies that have been studied [P. cepacia(=P. multivorans),P. caryophylli, P. marginata(=P. alliicola),P. pseudomallei, P. acidovorans, P. testosteroni, P. solanacearum, P. diminuta, P. facilis, P. delafieldii, P. saccharophila, P. palleronii]. A limited numerical analysis of the phenotypic properties of the examined strains supported, with some exceptions, their previous allocation to nomenspecies and biotypes. The internal structure and nomenclature of the “P. fluorescenshomology complex” are discussed.
Effect of Ammonia on the Synthesis and Function of the N
2
-Fixing Enzyme System in
Clostridium pasteurianum
Authors: Daesch Geraldine , Mortenson Leonard E.
Published: January 2020

The N
2
-fixing system of
Clostridium pasteurianum
operates under regulatory controls; no activity is found in cultures growing on excess NH
3
. The conditions which are necessary for the synthesis and function of this system were studied in whole cells by using acetylene reduction as a sensitive assay for the presence of the N
2
-fixing system. Nitrogenase of N
2
-fixing cultures normally can fix twice as much N
2
as is needed to maintain the growth rate. When cultures that have grown for four or more generations on NH
3
exhaust NH
3
from the medium, a diauxic lag of about 90 min ensues before growth is resumed on N
2
. Neither N
2
-fixing nor acetylene reduction activity can be detected before growth is resumed on N
2
. N
2
is not a necessary requirement for this synthesis since under argon that contains less than 10
−8
m
N
2
, the N
2
-fixing system is made. If NH
3
is added to N
2
-dependent cultures, synthesis of the enzyme system is abruptly stopped, but the enzyme already present remains stable and functional for at least 6 hr (over three generations). Cultures grown under argon in a chemostat controlled by limiting ammonia have derepressed nitrogenase synthesis. If the argon is removed and replaced by N
2
, partial repression of nitrogenase occurs.
Inhibition of Tryptophan Synthetase by Indoleacrylic Acid
Authors: Matchett William H.
Published: January 2020

Indoleacrylic acid (5 × 10
−4

m

in the growth medium) inhibits the growth of mycelia of
Neurospora crassa
and causes the cells to accumulate indoleglycerol phosphate. Measurement of kinetic parameters of partially purified tryptophan synthetase in the presence of indoleacrylic acid showed the following patterns of inhibition: in Reaction 1, the physiological reaction, indoleglycerol phosphate + serine [Formula: see text] tryptophan + glyceraldehyde-3-phosphate (unusual with respect to indoleglycerol phosphate, partially competitive with respect to serine); in Reaction 2, indole + serine [Formula: see text] tryptophan (unusual with respect to indole, partially competitive with respect to serine); in Reaction 3, indoleglycerol phosphate [Formula: see text] indole + glyceraldehyde-3-phosphate (no inhibition observed). The effects of indoleacrylic acid on whole cells were completely reversed by equimolar concentrations of tryptophan but not by indole. The addition of a 10-fold molar excess of serine to the medium completely reversed the effects. The accumulation of indoleglycerol phosphate appears to be the result of the partial blockage of tryptophan synthetase, the resulting deprivation of tryptophan, and the consequent release of its physiological feedback control on anthranilate synthetase.
Biochemical and Genetic Studies on Ubiquinone Biosynthesis in
Escherichia coli
K-12: 4-Hydroxybenzoate Octaprenyltransferase
Authors: Young I. G. , Leppik R. A. , Hamilton J. A. , Gibson F.
Published: January 2020

Three ubiquinone-deficient mutants of
Escherichia coli
unable to convert 4-hydroxybenzoate into 3-octaprenyl-4-hydroxybenzoate were isolated and examined. The results of genetic analysis suggest that each of the mutants carries a mutation in a gene designated
ubiA
which can be represented at minute 79 on the
E. coli
chromosome map. The conversion of 4-hydroxybenzoate into 3-octaprenyl-4-hydroxybenzoate, catalyzed by 4-hydroxybenzoate octaprenyltransferase, was studied with a strain of
E. coli
that is blocked in the common pathway of aromatic biosynthesis and consequently accumulates the precursor of the side chain of ubiquinone. Both the side-chain precursor and 4-hydroxybenzoate octaprenyltransferase were shown to be membrane-bound. The enzyme required Mg
2+
for optimal activity. The
ubiA
−
mutants were found to lack 4-hydroxybenozate octaprenyltransferase activity, which suggested that the
ubiA
gene is the structural gene coding for this enzyme.
Temperature-Sensitive Mutants of
Escherichia coli
K-12 with Low Activity of the Diaminopimelic Acid Adding Enzyme
Authors: Lugtenberg E. J. J. , Van Schijndel-van Dam Arna
Published: January 2020

Five temperature-sensitive lysis mutants were found to possess very low diaminopimelic acid (Dpm) adding enzyme activity in vitro. Murein synthesis at 42 C was impaired, and uridine-5′-diphosphate-
N
-acetyl-muramyl-
l
-Ala-
d
-Glu (UDP-MurNAc-dipeptide) was accumulated. In the presence of NaCl, the mutants could grow at 42 C. NaCl had no influence on the Dpm adding enzyme activity in vitro. The growth rate of most temperature-resistant revertants was decreased, but their Dpm adding enzyme activity remained very low. Two revertants had a rather normal growth rate. Their Dpm adding enzyme activity was significantly increased, but much lower than in the wild type. The influence of growth rate on the viability of the mutants is discussed.
Glutamate Dehydrogenase from
Mycoplasma laidlawii
Authors: Yarrison Gerald , Young Diane W. , Choules G. L.
Published: January 2020

Mycoplasma laidlawii
possesses a single glutamate dehydrogenase (GDH) with dual coenzyme specificity [specificity for nicotinamide adenine dinucleotide (H) and nicotinamide adenine dinucleotide phosphate (H)]. A purification procedure is reported which results in an enzyme preparation with a specific activity of 79.5 units/mg and which displays only one significant protein band after gel electrophoresis. This one band was determined, by activity staining, to have all of the GDH nucleotide specificities. The molecular weight of the enzyme is 250,000 ± 10%, and it has a subunit size of about 48,000. The enzyme exhibits measurable activity with aspartate and pyruvate but is inactive with eight other possible substrates. Purine nucleotides do not affect the activity. The
K
m
for reduced nicotinamide adenine dinucleotide was 1.8 × 10
−4
m
. The optimal substrate concentrations and
p
H optimum for each of the respective GDH activities are also reported.
Effects of Chloramphenicol Isomers and Erythromycin on Enzyme and Lipid Synthesis Induced by Oxygen in Wild-Type and Petite Yeast
Authors: Gordon P. A. , Lowdon M. J. , Stewart P. R.
Published: January 2020

The synthesis of mitochondrial enzymes induced by exposure of anaerobically grown, lipid-depleted
Saccharomyces cerevisiae
to oxygen is inhibited by
d
(−)-
threo
-chloramphenicol and erythromycin. The concentration of these antibiotics required to cause 50% inhibition of this synthesis is less than 1 m
m
; this is also approximately the concentration required to inhibit by the same amount mitochondrial protein synthesis in situ. The synthesis of unsaturated fatty acids, ergosterol, and phospholipid induced by aeration is inhibited by
d
(−)-
threo
-chloramphenicol at high concentrations (12 m
m
) but is unaffected by erythromycin.
l
(+)-
threo
-Chloramphenicol affects neither enzyme nor lipid synthesis and is without effect on mitochondrial protein synthesis in situ. All three compounds inhibit the oxidative activity of isolated mitochondria; the chloramphenicol isomers also inhibit phosphorylation. In a euflavine-derived petite mutant, lacking mitochondrial protein synthesis and respiration, aeration results in the normal development of lipid in the cells, but no synthesis of mitochondrial enzymes.
d
(−)-
threo
-Chloramphenicol does not inhibit lipid synthesis in these cells. Thus inhibition of mitochondrial protein synthesis with erythromycin or genetic deletion of mitochondrial protein synthesis results in loss of the capacity to synthesize enzymes during aeration.
d
(−)-
threo
-Chloramphenicol, as well as inhibiting induced enzyme formation, inhibits lipid synthesis induced by oxygen. It is unlikely that the latter effect of chloramphenicol is due to inhibition of energy production and transformation, to direct effects on lipid synthesis, or to an inhibition of mitochondrial protein synthesis. It is, however, an effect not shared with the
l
isomer.
Nonchromosomal Antibiotic Resistance in Bacteria V. Isolation and Characterization of R Factor Mutants Exhibiting Temperature-Sensitive Repression of Fertility
Authors: Silver Richard P. , Cohen Stanley N.
Published: January 2020

Several distinct types of derepressed R factor mutants have been isolated and identified following nitrosoguanidine mutagenesis. One class of mutants appears to synthesize a temperature-sensitive repressor substance, as shown by the effects of temperature on R factor transfer, on male-specific phage sensitivity, and on F factor and Hfr transfer. In addition, two classes of repressor-in-sensitive derepressed R factor mutants have been identified: although both inhibit F factor transfer at 42 and 32 C, one mutant (R6-5
drd
50) represses its own fertility at only the low temperature. These results imply the existance of a plasmid-specific component of the R factor repression system, in addition to a component which acts on both R and F factor fertility.
Mechanism of Nitrification by
Arthrobacter
sp
Authors: Verstraete W. , Alexander M.
Published: January 2020

Resting cells of
Arthrobacter
sp. excrete as much as 60 μg of hydroxylamine-nitrogen per ml when supplied with ammonium. An organic carbon source in abundant supply is necessary for the oxidation. Resting cells oxidize hydroxylamine to nitrite and 1-nitrosoethanol, the former accumulating only when an exogenous carbon source is available. Cell-free extracts contain an enzyme catalyzing the formation of hydroxylamine from acetohydroxamic acid, a hydroxylamine-nitrite oxido-reductase, and an enzyme producing nitrite and nitrate from various primary nitro compounds. Nitrite is not produced from hydroxylamine by the extracts, but 1-nitrosoethanol is formed from hydroxylamine in the presence of acetate. 1-Nitrosoethanol is also produced from acetohydroxamic acid by these preparations. Nitrite was formed from hydroxylamine, however, by extracellular enzymes excreted by the bacterium.
Effect of Zn
2+
on Bacterial Conjugation: Inhibition of Mating Pair Formation
Authors: Ou Jonathan T. , Anderson Thomas F.
Published: January 2020

Zn
2+
at 10
−3
m
has been found to block the formation of mating pairs between Hfr and F
−
strains of
Escherichia coli
as observed both by light microscopy and by Coulter counter measurements. Kinetic studies show that Zn
2+
reduces the fertility of the male and that its effect disappears within 2 min after Zn
2+
has been removed from the medium. Short treatments of female cells with Zn
2+
have no detectable effect on their ability to form mating pairs. Later steps in the mating process such as mobilization of the male chromosome, transfer of the chromosome to the female, or its integration into the female chromosome seem not to be affected by 10
−3
m
Zn
2+
.
Levels of Nicotinamide Adenine Dinucleotide and Reduced Nicotinamide Adenine Dinucleotide in Facultative Bacteria and the Effect of Oxygen
Authors: Wimpenny Julian W. T. , Firth Anne
Published: January 2020

Nicotinamide adenine dinucleotide (NAD) and reduced NAD (NADH) levels have been measured in bacterial cultures. The cofactors were assayed by using the very sensitive cycling assay described previously by Cartier. Control experiments showed that the level of total NAD(H) falls during harvesting, and so samples were taken quickly from growing cultures and extracted immediately without separating the cells from the medium. Total NAD(H) ranged from 4.0 to 11.7 μmoles/g of dry cells for three facultative organisms,
Klebsiella aerogenes, Escherichia coli
, and
Staphylococcus albus
. NADH was remarkably constant in these bacteria; only one out of ten series of determinations was outside the range 1.4 to 1.9 μmoles/g of dry cells. NAD
+
showed much greater variation. An anaerobe (
Clostridium welchii
) had significantly more total NAD(H) whereas an aerobe
Pseudomonas aeruginosa
had about as much NAD(H) as the facultative organisms. NAD and NADH were measured during growth: once more NADH was much more constant than NAD. During change-over between aerobiosis and anaerobiosis, NADH showed a temporary increase but then returned to a constant level, whereas NAD changed from high aerobically to low anaerobically. These results are discussed in terms of the control mechanisms that may be involved.
Location of Polysaccharide onChlamydia psittaciby Silver-Methenamine Staining and Electron Microscopy
Authors: Dhir Sanittar P. , Boatman Edwin S.
Published: January 2020

Previous serological studies have indicated that the group antigen of chlamydial organisms is composed of an acidic polysaccharide and a lipid component. The present study was undertaken in an effort to locate this polysaccharide complex by use of electron microscopy and a silver-methenamine marker. The meningopneumonitis strain ofChlamydia psittaciwas propagated in HeLa-M cell culture. Organisms were purified by differential centrifugation, treatment with Genetron, and by gel filtration. After fixation and embedding, sections were obtained for electron microscopy. Sections were stained for carbohydrates with silver-methenamine. A double layer of regularly spaced silver grains of uniform size was observed at the periphery of the sectioned organisms tracing the contours of the surface membrane (cell wall). This intensity of staining was observed only when sections were oxidized with periodate prior to silver-methenamine staining. Prior treatment with 1% sodium deoxycholate resulted in a significant reduction in staining. It is considered probable that the periodate-sensitive polysaccharide found at the periphery of the organisms represents, or is a component of, the group antigen of these organisms.
Nature of the Receptor Substance of
Mycobacterium smegmatis
for D4 Bacteriophage Adsorption
Authors: Furuchi Atsuko , Tokunaga Tohru
Published: January 2020

The acetone-soluble fraction extracted from lyophilized cells of
Mycobacterium smegmatis
ATCC 607 inhibited D4, a species-specific phage active against
M. smegmatis
. Evidence is presented indicating that the D4 inhibition was caused by the phage receptor substance(s) contained in this fraction. A fraction eluted from silicic acid with chloroform-methanol (95:5, v/v) showed the strongest inhibition of D4 phage. This fraction contained sugars and amino acids, and its infrared absorption spectrum was practically identical with those of the mycoside C isolated from the other species of mycobacteria. Further fractionation revealed that the active material was a mixture of several closely related peptidoglycolipids all of which showed, more or less, the phage inhibition. One of the compounds was purified and partially characterized; it contains three different amino acids,
allo
-threonine, alanine, and phenylalanine, at a molar ratio of 1:1:1, and also three different deoxyhexoses, probably 6-deoxytalose, 3,4-di-
o
-methylrhamnose, and 2,3,4-tri-
o
-methylrhamnose. A tentative name of “mycoside C
sm
” is proposed for this substance which possesses a slightly different structure from the known types of mycoside C and is probably specific for the species of
M. smegmatis
. A fraction extracted from the D4-resistant mutant of
M. smegmatis
ATCC 607 by acetone and then by chloroform-methanol (95:5, v/v) showed no phage inhibition and had no sugar component. In addition, this fraction contained lysine, serine, and a small amount of both glycine and an unidentified amino acid.
Response of the Intracellular Adenosine Triphosphate Pool of
Saccharomyces cerevisiae
to Growth Inhibition Induced by Excess
l
-Methionine
Authors: Bailey R. B. , Parks L. W.
Published: January 2020

Yeast cells accumulate
S
-adenosyl-
l
-methionine (S-AM) when cultivated in the presence of
l
-methionine. Cell growth is inhibited by the addition of high concentrations of
l
-methionine. A number of investigators have attributed this to the depletion of adenosine triphosphate (ATP) as a consequence of the utilization of that mucleotide for S-AM formation. The cellular ATP pool of
Saccharomyces cerevisiae
was measured during growth inhibition caused by addition of excess
l
-methionine. Polyethylenimine thin-layer chromatography and subsequent autoradiography were used to quantitate the extracted ATP. Addition of
l
-methionine to a level of 5 mg/ml in a culture during exponential growth caused an increase in the doubling time of 40 to 50%. During this period, the cellular ATP level continued increasing normally and, as the cells entered stationary growth, receded to a level characteristic of an uninhibited stationary culture growth. After the addition of methionine, there was never an observed depletion of the ATP pool other than the normal fluctuation which occurs in an uninhibited culture. We have concluded that growth inhibition by excessive methionine does not result from limiting availability of ATP.
Minimal Requirements for Commitment to Sporulation in
Bacillus megaterium
Authors: Greene Richard A. , Slepecky Ralph A.
Published: January 2020

Commitment to sporulation was examined by means of both endotrophic sporulation and rejuvenation experiments. In both cases, a point of commitment to the completion of sporulation occurred at stage II. With 2 × 10
8
cells/ml, the process by which commitment occurred required 0.5 m
m
Mg
2+
, 10.0 m
m
phosphate, and an energy source (minimum of 5.0 m
m
acetate). For completion of sporulation and formation of normal, heat-resistant refractile spores, 0.3 m
m
Ca
2+
was required. Except for this Ca
2+
requirement, the completion of sporulation after commitment was independent of the nature of the surrounding medium. Some aspects of the utilization of these required substances were examined.
Iron Uptake in
Salmonella typhimurium
: Utilization of Exogenous Siderochromes as Iron Carriers
Authors: Luckey Mary , Pollack Jay R. , Wayne Rush , Ames Bruce N. , Neilands J. B.
Published: January 2020

Aerobic microorganisms have evolved a variety of siderochromes, special ligands which can dissolve insoluble ferric iron and facilitate its transport into the cell. We have found that
enb
mutants of
Salmonella typhimurium
blocked in the biosynthesis of enterobactin (its natural iron carrier) are able to utilize siderochromes of different types made by other microorganisms as iron carriers. The antibiotic albomycin δ
2
was used to select mutants defective in ferrichrome-mediated iron uptake. Twelve classes of albomycin-resistant mutants, named
sid
, were defined on the basis of their growth responses to other siderochromes. Most of these classes have genetic lesions in loci that are cotransduced with
panC
(represented at 9 min on the genetic map). The locus designated
sidJ
is cotransduced with
enb
, whereas
sidK
and
sidL
are linked with neither
panC
nor
enb
. Genetic and physiological data indicate that
S. typhimurium
has several transport systems of high specificity for a variety of siderochromes produced by other microorganisms.
Nonidentity of the Aspartate and the Aromatic Aminotransferase Components of Transaminase A in
Escherichia coli
Authors: Collier R. H. , Kohlhaw G.
Published: January 2020

Tyrosine, added to the growth medium of a strain of
Escherichia coli
K-12 lacking transaminase B, repressed the tyrosine, phenylalanine, and tryptophan aminotransferase activities while leaving the aspartate aminotransferase activity unchanged. This suggested that the aspartate and the aromatic aminotransferase activities, previously believed to reside in the same protein, viz. transaminase A, are actually nonidentical. Further experiments showed that, upon incubation at 55 C, the aspartate aminotransferase of crude extracts was almost completely stable, whereas the tyrosine and phenylalanine activities were rapidly inactivated. Apoenzyme formation was faster, and apoenzyme degradation proceeded more slowly with aspartate aminotransferase than with tyrosine aminotransferase. Electrophoresis in polyacrylamide gels separated the aminotransferases. A more rapidly moving band contained tyrosine, phenylalanine, and tryptophan aminotransferases, and a slower band contained aspartate aminotransferase. A mutant of E. coli K-12 with low levels of aspartate aminotransferase exhibited unchanged levels of tyrosine aminotransferase. Thus, transaminase A appears to be made up of at least two proteins: one of broad specificity whose synthesis is repressed by tyrosine and another, specific for aspartate, which is not subject to repression by amino acids. The apparent molecular weights of both the aspartate and the aromatic aminotransferases, determined by gel filtration, were about 100,000.
Inositol Phosphate Phosphatases of Microbiological Origin: the Inositol Pentaphosphate Products of
Aspergillus ficuum
Phytases
Authors: Irving G. C. J. , Cosgrove D. J.
Published: January 2020

The fungus
Aspergillus ficuum
NRRL 3135 is known to produce an extracellular nonspecific orthophosphoric monoester phosphohydrolase (EC 3.1.3.2) with a
p
H optimum of 2.0, as well as an extracellular
myo
-inositol hexaphosphate phosphohydrolase (EC 3.1.3.8; phytase) with
p
H optima of 2.0 and 5.5. Both these enzymes are also known to hydrolyze
myo
-inositol hexaphosphate. The pentaphosphates liberated in the first step of this hydrolysis have been isolated and identified by ion-exchange chromatography and optical rotation. The nonspecific orthophosphoric monoester phosphohydrolase produces a single pentaphosphate,
d
-
myo
-inositol-1,2,4,5,6-pentaphosphate, whereas the phytase, at both
p
H 2.0 and 5.5, produces a mixture of two pentaphosphates. The major component of this mixture is
d
-
myo
-inositol-1,2,4,5,6-pentaphosphate and the other is
d
-
myo
-inositol-1,2,3,4,5-pentaphosphate. Thus the pathways of dephosphorylation of
myo
-inositol hexaphosphate by these two enzymes differ from that of wheat-bran phytase which forms
l
-
myo
-inositol-1,2,3,4,5-pentaphosphate.
Reversion of Ribosomal Helix Formation in
Escherichia coli
Authors: Silverman David J. , Voelz Herbert
Published: January 2020

After transfer into fresh medium,
Escherichia coli
cells containing ribosomal helices resume growth without a lag period. The helices disappear within 15 min after transfer, the number of 70
S
ribosomes decreases, and a steady-state ribosomal profile appears within one cell generation time. Subunits isolated from the helices support in vitro protein synthesis, but efficiency is optimal only when supplemented with an undetermined factor that is contained in the S-100 fraction of log-phase cells. The data suggest a possible role of helices as ribosomal reserve units.
Initiation of Deoxyribonucleic Acid Replication in
Escherichia coli
B/r: Chronology of Events and Transcriptional Control of Initiation
Authors: Messer Walter
Published: January 2020

Three processes necessary for the initiation of deoxyribonucleic acid replication have been separated in time in synchronously growing
Escherichia coli
B/r. One can be inhibited with 2 μg of chloramphenicol per ml and occurs about 20 min prior to initiation. A second step, occurring 5 to 10 min prior to initiation, is sensitive to 4 to 30 μg of chloramphenicol per ml. A third process occurs at the time of initiation and can be inhibited with rifampin. The experiments suggest that transcription itself, or the synthesis of a relatively small ribonucleic acid, is required for initiation of replication.
Interspecies Transformation of
Acinetobacter
: Genetic Evidence for a Ubiquitous Genus
Authors: Juni Elliot
Published: January 2020

The availability of a strain of
Acinetobacter
competent for transformation has made it possible to demonstrate the genetic relatedness of a large variety of gram-negative, oxidase-negative, nonmotile, and aerobic coccobacilli originally classified into eleven different genera. Deoxyribonucleic acid (DNA) species from 265 such strains are capable of transforming stable auxotrophs of the competent
Acinetobacter
to prototrophy. The compositions of these DNA species vary from 40 to 46.8% guanine plus cytosine. Strains with widely differing phenotypic properties are also included in this collection of acinetobacters. DNA species from all oxidase-positive strains of
Moraxella
and from a variety of common bacteria are unable to transform the competent
Acinetobacter
. Although acinetobacters are usually considered to be unable to reduce nitrate to nitrite, six strains known to carry out this reduction have been shown to be authentic acinetobacters since their DNA species readily transform the competent
Acinetobacter
auxotrophs to prototrophy. In contrast to previous findings that acinetobacters rarely grow with glucose as a sole carbon source, the results of the present study show that 17 of the 265 strains grow readily in a glucosemineral medium, and 48 other strains can mutate spontaneously to grow in such a medium. A second competent strain of
Acinetobacter
, originally unable to use glucose,
d
-xylose, or
d
-ribose as carbon sources, has been transformed for ability to dissimilate these compounds using DNA species from strains that normally grow on these sugars. Although most of the 265
Acinetobacter
strains studied were originally grown on complex media when isolated from human sources, only nine of these strains require growth factors in order to grow in a mineral medium containing a single carbon and energy source. A simple transformation assay has been devised for rapid examination of large numbers of strains to determine whether or not they are acinetobacters. This assay, which is suitable for routine diagnostic work, includes a procedure for preparation of crude transforming DNA from a small quantity of bacterial paste. Samples of DNA prepared from
Acinetobacter
cultures that had died on slants and plates were still able to effect transformation of the competent auxotrophs to prototrophy.
Isolation of the
rec
Mutants in
Staphylococcus aureus
Authors: Inoue Matsuhisa , Oshima Hiroshi , Okubo Toyoji , Mitsuhashi Susumu
Published: January 2020

A histidine auxotroph (
his
−) of
Staphylococcus aureus
MS3937 and mutants sensitive to ultraviolet (UV) irradiation were obtained. The UV-sensitive mutants were found also to be sensitive to
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine and mitomycin C, and their sensitivity was accounted for by a defect in deoxyribonucleic acid repair. Transduction of either chromosomal or plasmid markers to UV-sensitive mutants showed that these staphylococcus mutants are of the
recA
(reckless) type mutants as reported in
Escherichia coli
and
Salmonella typhimurium;
therefore the UV-sensitive mutants (
uvr
−) were renamed recombination-deficient mutants (
rec
−). The biochemical and genetic properties of these mutants are described, and their usefulness for studies of staphylococcal plasmids is discussed.
Isolation of the Lipid Intermediate in Peptidoglycan Biosynthesis from
Escherichia coli
Authors: Umbreit Jay N. , Strominger Jack L.
Published: January 2020

The lipid intermediate in peptidoglycan biosynthesis was isolated from
Escherichia coli
strain W and characterized as C
55
-isoprenyl-pyrophosphoryl
N
-acetylmuramyl(-pentapeptide)-
N
-acetyl-glucosamine.
Studies on Sex Pili: Mutants of the Sex Factor F in
Escherichia coli
Defective in Bacteriophage-Adsorbing Function of F Pili
Authors: Tomoeda Munemitsu , Shuta Akemi , Inuzuka Manabu
Published: January 2020

Ultraviolet irradiation or nitrosoguanidine treatment of
Escherichia coli
K-12 strain JE3100 (F′
8
/
fla pil
) led to the isolation of six mutants defective in F pili function. The defects were shown to be caused by mutations in the F factor. The mutants retained conjugal fertility, although they were less efficient than parental F′
8
strain, and continued to synthesize F pili. Three of the mutants (strains KE196, 198, and 200) had lost sensitivity to male-specific MS2 phage, and the other three (strains KE161, 163, and 164) were insensitive to Qβ and f1 as well as MS2 phages. F pili on strains KE196, 198, and 200 cells continued to adsorb MS2 phage, whereas those of strains KE161, 163, and 164 did not adsorb MS2 phage. The correlation of the mutant phenotypes with those of other F mutants reported in the literature is discussed.
Murein and the Outer Penetration Barrier of
Escherichia coli
K-12,
Proteus mirabilis
, and
Pseudomonas aeruginosa
Authors: Burman Lars G. , Nordström Kurt , Bloom Gunnar D.
Published: January 2020

A penetration barrier operating outside the periplasmic enzyme penicillinase was studied in an ampicillin-resistant mutant of
Escherichia coli
K-12. Growth in the presence of lysozyme and sublethal concentrations of ampicillin partially opened the barrier. This could be recorded as an increased penetration of penicillin G, sodium cholate, and rifampin to their respective targets. Brief treatments with tris(hydroxymethyl)aminomethane-ethylenediaminetetraacetic acid and sodium cholate effectively impaired the barrier against penicillin and also caused leakage of penicillinase. Wild-type
E. coli
K-12,
Proteus mirabilis
, and
Pseudomonas aeruginosa
also showed an increased sensitivity to cholate after treatment with penicillins. Electron micrographs showed that lysis by cholate was due to a distortion of the cytoplasmic membrane causing a leakage of protein and RNA from the cells to the medium. Physiological data indicated that the increased sensitivity to cholate induced by growth in the presence of ampicillin or lysozyme was due to effects upon the murein. This was supported by measurement of the incorporation of
3
H-diaminopimelic acid. These results indicate that the murein sacculus either is a part of the penetration barrier or is responsible for holding the structure of the outer membrane together.
Comutation in
Streptomyces
Authors: Randazzo Rosalba , Sermonti Giuseppe , Carere Angelo , Bignami Margherita
Published: January 2020

Up to 6% of
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine-induced back mutations in the
hisA
locus of
Streptomyces coelicolor
were forward mutations (comutations) in another closely linked
his
locus.
Accumulation of Guanosine Tetraphosphate in T7 Bacteriophage-Infected
Escherichia coli
Authors: Friesen J. D. , Fiil N.
Published: January 2020

Accumulation of guanosine tetraphosphate (ppGpp) in
Escherichia coli
strain AS19
valS
, carrying a temperature-sensitive valyl-transfer ribonucleic acid synthetase and infected with bacteriophage T7, was studied. Valine starvation was achieved by culturing this strain at 42 C. Addition of rifampin to an uninfected culture at the nonpermissive temperature resulted in loss of accumulated ppGpp; however, cultures infected with phage T7, treated with rifampin, and then shifted to the nonpermissive temperature maintained the ability to accumulate ppGpp. Moreover, treatment of the T7-infected culture with rubidomycin, an antibiotic which inhibits transcription, did not reduce the amount of ppGpp accumulated following shift to the nonpermissive temperature. Measurements of the instantaneous rate of T7 transcription showed that it is not under stringent control of amino acids. ppGpp synthesized in T7-infected
E. coli
appears to be more stable than its counterpart in an uninfected culture. These results are interpreted to mean that ppGpp production is not directly dependent on transcription and arises instead from inhibition of another reaction, most likely some aspect of translation.
Germination of
Azotobacter vinelandii
Cysts: Sequence of Macromolecular Synthesis and Nitrogen Fixation
Authors: Loperfido Bonnie , Sadoff H. L.
Published: January 2020

Azotobacter vinelandii
cysts undergo conversion to vegetative cells in Burk's nitrogen-free medium utilizing glucose, sucrose, or acetate. In 1% glucose, this overall process was complete in 8 hr and consisted of a germination and an outgrowth phase. Respiration, ribonucleic acid, and protein synthesis began soon after the addition of the germinant, and these processes proceeded at rates characteristic of the germination. The rates of respiration and synthesis increased sharply between 4 and 5 hr, the beginning of the outgrowth, at which time deoxyribonucleic acid synthesis and nitrogen fixation began. Respiration, macromolecular synthesis and nitrogen fixation continued at high rates until the emergence of vegetative cells from the cyst coats.
Levels of Glycogen and Trehalose in
Mycobacterium smegmatis
and the Purification and Properties of the Glycogen Synthetase
Authors: Elbein Alan D. , Mitchell Mike
Published: January 2020

The levels of glycogen, free trehalose, and lipid-bound trehalose were compared in
Mycobacterium smegmatis
grown under various conditions of nitrogen limitation. In a mineral salts medium supplemented with yeast extract and containing fructose as the carbon source, the accumulation of glycogen increased dramatically as the NH
4
Cl content of the medium was lowered. However, levels of free trehalose remained relatively constant. Cells were grown in low nitrogen medium and were then shifted to medium containing high nitrogen. Under these conditions, there was a rapid accumulation of glycogen in low nitrogen, and this glycogen was rapidly depleted when cells were placed in high nitrogen medium. Again the concentration of free trehalose remained fairly constant. However, when cells were grown in low nitrogen medium with [
14
C]fructose and then transferred to high nitrogen medium with unlabeled fructose, the specific radioactivity (counts per minute per micromole) of the free trehalose fell immediately, indicating that it was being synthesized and turned over continually. On the other hand, the specific radioactivity of the glycogen and bound trehalose declined much more slowly, suggesting that these two compounds were not turning over as rapidly or were being synthesized at a much slower rate. Experiments on the incorporation of [
14
C]fructose into glycogen and trehalose indicated that cells in high nitrogen medium synthesized much less glycogen than those in low nitrogen. However, synthesis of both free trehalose and bound trehalose was the same in both cases. The specific enzymatic activities of the glycogen synthetase and the trehalose phosphate synthetase varied somewhat from one growth condition to another, but there was no correlation between enzymatic activity and the amount of glycogen or trehalose, suggesting that changes in glycogen levels were not due to increased synthetic capacity. The glycogen synthetase was purified about 35-fold and its properties were examined. This enzyme was specific for adenosine diphosphate glucose as the glucosyl donor.
Isolation and Characterization of Mutations Affecting the Transport of Hexose Phosphates in
Escherichia coli
Authors: Kadner Robert J. , Winkler Herbert H.
Published: January 2020

Mutants of
Escherichia coli
defective in the hexose phosphate transport system were isolated. Negative selection by penicillin treatment or positive selection with phosphonomycin was employed. These mutants grew normally on all carbon sources other than hexose phosphates. The map location of the mutations in 18 independently isolated mutant strains was investigated by transduction crosses. All of the mutations were found to lie in the same region of the chromosome, in the region represented by min 72 on the Taylor map. The order of the genes in this region was found to be
mtl-cysE-pyrE-uhp-bgl-ilv
. Revertants of some of the mutants exhibited altered regulatory control of this transport system.