bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth Rates of
Sulfolobus acidocaldarius
in Nature
Authors: Mosser J. L. , Bohlool B. B. , Brock T. D.
Published: January 2020

Turnover times for water passing through several
Sulfolobus acidocaldarius
-containing springs were determined by measuring the dilution rates of small amounts of sodium chloride that were added to the springs. Chloride was diluted out exponentially, while concentrations of the bacteria remained constant. Additionally, temperature, pH, and chemical composition of the springs also remained constant during the time that the chloride was being diluted. The springs are thus steady-state systems, and since the rates of bacterial growth must be at least equal to the chloride dilution rates, minimal doubling times for the bacterial populations can be calculated. Half-times for chloride dilution, equivalent to bacterial doubling times, were on the order of 10 to 20 h for springs ranging in volume from about 20 to 2,000 liters, but approximately 30 days for two larger springs of about 1 million liters. Formaldehyde-fixed cells of a serologically distinguishable strain of
S. acidocaldarius
were also added as markers to four of the smaller springs, and the dilution rates of these bacteria were compared with the chloride dilution rates. The rates agreed reasonably well, thus verifying the growth rates obtained from the chloride dilution rates. In three springs, exponential growth was studied by draining the springs and allowing them to refill with bacteria-free water. Exponential doubling times were on the order of a few hours, much more rapid than steady-state doubling times. The methods used in this work may have wider utility in aquatic environments.
Phenotypic Suppression of Phosphofructokinase Mutations in
Escherichia coli
by Constitutive Expression of the Glyoxylate Shunt
Authors: Vinopal R. T. , Fraenkel D. G.
Published: January 2020

Fructose-6-phosphate kinase (
pfkA
) mutants have impaired growth on carbon sources which enter glycolysis at or above the level of fructose-6-phosphate, but the degree of impairment depends on the carbon source (e.g., growth on glucose is very much slower than growth on glucose-6-phosphate). The present report contains considerable data on this complicated growth phenotype and derives mainly from the finding of a class of partial revertants which grow as fast on glucose as on glucose-6-phosphate; the reversion mutation is shown to be constitutivity of the glyoxylate shunt (

iclR
c

).

iclR
c

does not increase the fructose-6-phosphate kinase level in the mutants, and the exact mechanism of the partial phenotypic suppression is not understood. However,

iclR
c

was already known to suppress some mutations which affected phosphoenolpyruvate levels, and H. L. Kornberg and J. Smith have suggested (1970) that the growth phenotype of
pfkA
mutants might be related to pathways of phosphoenolpyruvate formation. Surprisingly, the hexose-monophosphate shunt is not necessary for the suppression, which therefore must act to restore metabolism via the residual phosphofructokinase activity present in all
pfkA
mutants. A mutant totally lacking phosphofructokinase activity was not suppressed.
Proline Excretion and Indirect Suppression in
Escherichia coli
and
Salmonella typhimurium
Authors: Berg Claire M. , Rossi John J.
Published: January 2020

The last step in proline biosynthesis in
Escherichia coli
K-12,
Salmonella typhimurium
LT7, and a number of other enterobacterial isolates is regulated so that no proline is excreted, even if excess Δ
1
-pyrroline-5-carboxylate, the immediate precursor of proline, is added to a culture. In proline auxotrophs blocked at an early step in proline biosynthesis (
proA
or
proB
), reversion to prototrophy is often due to a mutation in the arginine pathway which diverts
N
-acetyl glutamate γ-semialdehyde to proline synthesis, thus bypassing the
proA
or
proB
block. In such double mutants (
proAB, argD
), the last step in proline synthesis appears to be unregulated, since proline is excreted. Feedback inhibition and repression of the arginine pathway overcomes indirect suppression (restoring the Pro
−
phenotype), but proline regulation is not restored; double mutants still excrete proline when fed Δ
1
-pyrroline-5-carboxylate exogeneously. A new class of proline analogue-resistant mutant, due to mutation at
argD
, is also described.
Evidence for a Composite State of an F′
his,gnd
Element and a Cryptic Plasmid in a Derivative of
Salmonella typhimurium
LT2
Authors: Oliver Daphna R. , Manis Jack J. , Whitfield Harvey J.
Published: January 2020

A method designed to select mutants constitutive for expression of the histidine operon has been applied to a
Salmonella typhimurium
LT2 strain containing an F′
his,gnd
element and a cryptic plasmid. One of the mutants isolated, strain AA0019, has not only increased levels of histidinol phosphate phosphatase (
hisB
), but also increased levels of gluconate-6-phosphate dehydrogenase (
gnd
). Ultracentrifugation studies of extrachromosomal deoxyribonucleic acid (DNA) isolated from strain AA0019 revealed the presence of a single species of covalently closed circular (CCC) DNA that sedimented more rapidly through neutral and alkaline sucrose gradients than any of its possible plasmid precursors. From neutral sucrose gradients, sedimentation coefficients of 130, 100, and 86
S
were derived, corresponding to the CCC DNA of the large plasmid in strain AA0019, the F′
his,gnd
element and the cryptic LT2 plasmid, respectively. An
Escherichia coli
plasmid-free strain that upon mating had received the large 130S plasmid also contained 86
S
and 100
S
CCC DNA components. A histidine-requiring derivative of strain AA0019 obtained after acridine orange treatment retained the cryptic plasmid DNA. Apparently, the large plasmid in strain AA0019 consists of the F′
his,gnd
element and the cryptic LT2 plasmid of the parental strain.
Nitrogenase Activity and Photosynthesis in
Plectonema boryanum
Authors: Weare N. M. , Benemann John R.
Published: January 2020

Nitrogen-starved
Plectonema boryanum
594 cultures flushed with N
2
/CO
2
or A/CO
2
(99.7%/0.3%, vol/vol) exhibited nitrogenase activity when assayed either by acetylene reduction or hydrogen evolution. Oxygen evolution activities and phycocyanin pigments decreased sharply before and during the development of nitrogenase activity, but recovered in the N
2
/CO
2
cultures after a period of active nitrogen fixation. Under high illumination, the onset of nitrogenase activity was delayed; however, the presence of 3-(3, 4-dichlorophenyl)-1, 1-dimethylurea (DCMU) eliminated this lag. Oxygen was a strong and irreversible inhibitor of nitrogenase activity at low (>0.5%) concentrations. In the dark, low oxygen tensions (0.5%) stimulated nitrogenase activity (up to 60% of that in the light), suggesting a limited but significant respiratory protection of nitrogenase at low oxygen tensions. DCMU was not a strong inhibitor of nitrogenase activity. A decrease in nitrogenase activity after a period of active nitrogen fixation was observed in the N
2
/CO

2
−

, but not in the A/CO

2
−

, flushed cultures. We suggest that this decrease in nitrogenase activity is due to exhaustion of stored substrate reserves as well as inhibition by the renewed oxygen evolution of the cultures. Repeated peaks of alternating nitrogenase activity and oxygen evolution were observed in some experiments. Our results indicate a temporal separation of these basically incompatible reactions in
P. boryanum
.
Biosynthetic Dihydroorotate Dehydrogenase from
Lactobacillus bulgaricus
: Partial Characterization of the Enzyme
Authors: Taylor W. Herman , Taylor Craig D. , Taylor Mary L.
Published: January 2020

Some of the catalytic properties of the biosynthetic dihydroorotate dehydrogenase purified from an anaerobic bacterium,
Lactobacillus bulgaricus
, are described. Studies with
p
-hydroxymercuribenzoate,
N
-ethylmaleimide, and mercuric chloride showed that sulfhydryl groups are necessary for transfer of electrons from dihydroorotate to a variety of electron acceptors. Protection studies with substrates for the enzyme indicated that free sulfhydryl groups at or near the active center are required for catalytic activity. Evidence is presented for the production of superoxide free radicals during reaction of the enzyme with molecular oxygen. Inhibitor studies with Tiron indicated that reduction of cytochrome
c
by the enzyme may involve the superoxide free radical as an intermediate. Orotate, one of the substrates for the enzyme, has been found to be a competitive inhibitor for the dihydroorotate site. The

K
i

for orotate as estimated by several techniques is 0.1 mM. The

K
m

for dihydroorotate with ferricyanide as the electron acceptor is estimated to be 0.5 mM.
Halophilic Nuclease from a Moderately Halophilic
Micrococcus varians
Authors: Kamekura Masahiro , Onishi Hiroshi
Published: January 2020

The moderately halophilic bacterium
Micrococcus varians
, isolated from soy sauce mash, produced extracellular nuclease when cultivated aerobically in media containing 1 to 4 M NaCl or KCl. The enzyme, purified to an electrophoretically homogeneous state, had both ribonuclease and deoxyribonuclease activities. The nuclease had maximal activity in the presence of 2.9 M NaCl or 2.1 M KCl at 40 C. The enzymatic activity was lost by dialysis against low-salt buffer, whereas when the inactivated enzyme was dialyzed against 3.4 M NaCl buffer as much as 77% of the initial activity could be restored.
Heterogeneity in Lipid Composition of the Outer Membrane and Cytoplasmic Membrane of
Pseudomonas
BAL-31
Authors: Diedrich D. L. , Cota-Robles E. H.
Published: January 2020

The outer membranes and cytoplasmic membranes of the marine bacterium
Pseudomonas
BAL-31 were separated by washing the cells three times in 0.5 M NaCl and twice in 0.5 M sucrose. Electron microscopy during the removal of membranes revealed that the outer membranes fragmented in a regular manner to give rise to fairly uniform vesicles measuring approximately 140 nm in diameter. Isolated outer membranes had a buoyant density in sucrose of 1.230 g per cm
3
, whereas the cytoplasmic membranes had a density of 1.194 g per cm
3
. The removal of the outer membrane during the application of this procedure was monitored by measuring the release of 2-keto-3-deoxyoctulosonic acid and phospholipid. The cells lost 85.5% of their 2-keto-3-deoxyoctulosonic acid and 47.3% of their phospholipid during this treatment. Complete recovery of outer membrane material could be achieved. The removal of 25.5% of the 2-keto-3-deoxyoctulosonic acid and 0.9% of the phospholipid rendered the cells sensitive to lysis with Triton X-100. The phospholipid composition of the outer membrane was calculated to be 78.9% phosphatidylethanolamine and 16.1% phosphatidylglycerol. The phospholipid composition of the cytoplasmic membrane proved to be 71.5% phosphatidylethanolamine and 23.5% phosphatidylglycerol. The fatty acid composition was also found to be quantitatively heterogeneous between the two membranes.
Transformation of
Salmonella typhimurium
by Plasmid Deoxyribonucleic Acid
Authors: Lederberg Esther M. , Cohen Stanley N.
Published: January 2020

A modified transformation procedure that is effective for the introduction of plasmid deoxyribonucleic acid at high frequency into
Salmonella typhimurium
, as well as into
Escherichia coli
, is described. Transformed bacteria acquire a circular deoxyribonucleic acid species having the genetic and molecular characteristics of the transforming plasmid.
Bacterial Metabolism of
para
- and
meta
-Xylene: Oxidation of a Methyl Substituent
Authors: Davey John F. , Gibson David T.
Published: January 2020

Pseudomonas
Pxy was isolated on
p
-xylene as sole source of carbon and energy. Substrates that supported growth were toluene,
p
-methylbenzyl alcohol,
p
-tolualdehyde,
p
-toluic acid, and the analogous
m
-methyl derivatives, including
m
-xylene. Cell extracts prepared from
Pseudomonas
Pxy after growth with either
p
-xylene or
m
-xylene oxidized the
p
- and
m
-isomers of tolualdehyde as well as
p
-methylbenzyl alcohol. The same cell extracts also catalyzed a “meta” fission of both 3- and 4-methylcatechol. Treatment of
Pseudomonas
Pxy with
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine led to the isolation of two mutant strains.
Pseudomonas
Pxy-40, when grown on succinate in the presence of
p
-xylene, accumulated
p
-toluic acid in the culture medium. Under the same conditions
Pseudomonas
Pxy-82 accumulated
p
-toluic acid and also 4-methylcatechol. When
Pseudomonas
Pxy-82 was grown on succinate in the presence of
m
-xylene, 3-methylcatechol and 3-methylsalicylic acid were excreted into the culture medium. A pathway is proposed for the initial reactions utilized by
Pseudomonas
Pxy to oxidize
p
- and
m
-xylene.
Bacterial Degradation of 4-Hydroxyphenylacetic Acid and Homoprotocatechuic Acid
Authors: Sparnins Velta L. , Chapman Peter J. , Dagley Stanley
Published: January 2020

A species of
Acinetobacter
and two strains of
Pseudomonas putida
when grown with 4-hydroxyphenylacetic acid gave cell extracts that converted 3,4-dihydroxyphenylacetic acid (homoprotocatechuic acid) into carbon dioxide, pyruvate, and succinate. The sequence of enzyme-catalyzed steps was as follows: ring-fission by a 2,3-dioxygenase, nicotinamide adenine dinucleotide-dependent dehydrogenation, decarboxylation, hydration, aldol fission, and oxidation of succinic semialdehyde. Two new metabolites, 5-carboxymethyl-2-hydroxymuconic acid and 2-hydroxyhepta-2,4-diene-1,7-dioic acid, were isolated from reaction mixtures and a third, 4-hydroxy-2-ketopimelic acid, was shown to be cleaved by extracts to give pyruvate and succinic semialdehyde. Enzymes of this metabolic pathway were present in
Acinetobacter
grown with 4-hydroxyphenylacetic acid but were effectively absent when 3-hydroxyphenylacetic acid or phenylacetic acid served as sources of carbon.
Induction of Sporulation During Synchronized Chromosome Replication in
Bacillus subtilis
Authors: Mandelstam J. , Higgs Sonia A.
Published: January 2020

Synchronous chromosome replication was obtained in a culture of
Bacillus subtilis
temperature-sensitive mutants growing in a rich medium. At intervals during this replication, samples of cells were transferred to a poor medium to induce sporulation. The results show that the capacity of
B. subtilis
for induced sporulation reaches a peak about 15 min after chromosome replication has begun. This capacity then declines rapidly, but can be restored by initiating a new round of deoxyribonucleic acid replication. The possibility is discussed that sporulation can be induced only when the chromosome replication fork is passing through a stage 0 operon and that this may be located in the
cysA-sul
R
region of the chromosome.
Preliminary Characterization Studies on the
Neisseria catarrhalis
Respiratory Electron Transport Chain
Authors: Jurtshuk Peter , Milligan T. W.
Published: January 2020

The
Neisseria catarrhalis
respiratory electron transport system was examined in a sonic type particulate membrane fraction and shown to have a moderately active succinate as well as nonpyridine nucleotide-dependent
dl
-lactate oxidoreductase and a very active tetramethyl-
p
-phenylenediamine oxidase.
l
-Malate and
l
-glutamate oxidation were found to be dependent on pyridine nucleotides and exclusively associated with a soluble (or nonmembranous) fraction. The primary cytochrome components in the electron transport system appear to be
c
-type in nature (555 nm and 550 nm) as well as cytochrome
a
1
(600 nm) and cytochrome
o
.
Biodegradative
l
-Threonine Deaminase of
Salmonella typhimurium
Authors: Luginbuhl Geraldine H. , Hofler John G. , Decedue Charles J. , Burns R. O.
Published: January 2020

The threonine deaminase formed under anaerobic conditions by
Salmonella typhimurium
is induced by
l
-serine and
l
-threonine, is catabolite repressible, requires cyclic adenosine 3′,5′-monophosphate for its synthesis and adenylic acid for optimal activity, and is immunologically different from biosynthetic threonine deaminase.
Inducibility of β-Glucuronidase in Wild-Type and Hexuronate-Negative Mutants of
Escherichia coli
K-12
Authors: Novel G. , Didier-Fichet M. L. , Stoeber F.
Published: January 2020

In strain K-12 of
Escherichia coli
, β-glucuronidase synthesis was induced only by β-glucuronides: all intermediates of the hexuronate pathway able to enter the cells failed to induce the enzyme significantly. The induction pattern of β-glucuronidase clearly differentiates the mode of regulation of its synthesis from those of the subsequent enzymes of the pathway, which are induced by fructuronate and/or tagaturonate. In mutant strains blocked in glucuronate metabolism after the isomerase step, β-glucuronidase synthesis was still induced by a β-glucuronide. Glucuronate and fructuronate, which are accumulated and mutually interconverted within the cells, become good inducers of β-glucuronidase: they induce up to a level one-half that obtained in the wild-type strain in the presence of β-glucuronide alone. In an isomerase-negative strain where fructuronate is not produced, β-glucuronidase was no longer induced by β-glucuronide unless supplemented with fructuronate. In this strain, glucuronate alone or fructuronate alone exhibited greater inducing ability than in the wild-type strain. Moreover, fructuronate could also enhance glucuronate-induced synthesis of β-glucuronidase. Glucuronate was not able to activate β-glucuronideinduced synthesis of β-glucuronidase. Therefore, the induction of β-glucuronidase synthesis depends upon two factors which, when acting separately, are both poor inducers but can act cooperatively; one factor is β-glucuronide or glucuronate and the second is fructuronate. The specific inducing capacity of each of these three compounds as well as the hypothetical mechanism(s) of the action of fructuronate are discussed.
Methylation of Ribosomal Proteins in
Escherichia coli
Authors: Chang F. N. , Chang C. N. , Paik Woon Ki
Published: January 2020

Escherichia coli
was grown in a medium containing [1-
14
C]methionine and [
methyl
-
3
H]methionine, and the
3
H/
14
C ratio was determined for each of the ribosomal proteins derived from the 70
S
ribosome. Evidence indicates that six proteins from the 50
S
subunit were methylated: L7, L9, L11, L12, L18, and L33. Methylation of several other 50
S
proteins (such as L1, L3, L5, etc.) may also occur. The methylated amino acids in protein L11 have been characterized further and found to be predominately ε-trimethyllysine. A small amount of a compound tentatively identified as

N
G
, N′
G

-dimethylarginine was also detected.
Activation of Inactive Nitrogenase by Acid-Treated Component I
Authors: Nagatani H. H. , Shah Vinod K. , Brill Winston J.
Published: January 2020

When
Azotobacter vinelandii
was derepressed for nitrogenase synthesis in a N-free medium containing tungstate instead of molybdate, an inactive component I was synthesized. Although this inactive component I could be activated in vivo upon addition of molybdate to the medium, it could not be activated in vitro when molybdate was added to the extracts. Activation occurred, however, when an acid-treated component I was added to extracts of cells derepressed in medium containing tungstate. Acid treatment completely abolished component I activity. Mutant strains UW45 and UW10 were unable to fix N
2
. Both strains synthesized normal levels of component II but produced inactive component I. Acid-treated component I activated inactive component I in extracts of mutant strain UW45 but not mutant strain UW10. This activating factor could be obtained from N
2
-fixing
Klebsiella pneumoniae, Clostridium pasteurianum
, and
Rhodospirillum rubrum
.
Expression of Cryptic β-Fructofuranosidase in
Saccharomyces rouxii
Authors: Arnold Wilfred N.
Published: January 2020

Raffinose hydrolysis was studied in
Saccharomyces rouxii
. The responsible enzyme was identified as a β-fructofuranosidase (EC 3.2.1.26), which has a pH optimum of 5.5 and a

K
m

of 83 mM for raffinose. This enzyme was cryptic in cells from a 3-day culture. A 2-min treatment with 0.1 volume of ethyl acetate in sodium acetate buffer (pH 6) gave complete expression of the enzyme, which was still retained by the cell. Ghosts were prepared by modifying membrane structure with small basic proteins in distilled water, and after washing they showed the full complement of enzymatic activity. The enzyme remained cryptic in osmotically protected spheroplasts; however, after lysis (by dilution) release, as well as expression, was effected. Mechanical disruption of fresh cells revealed and released all of the enzyme. Cells in early stationary phase had all of their β-fructofuranosidase in a cryptic state. Aging yielded fractional expression of activity; initially this was proportional to cell death, but later the degree of expression exceeded the death rate. Media from aged cultures or cell-free extracts of aged cells were not effective in revealing the cryptic enzyme of younger cells.
S. rouxii
β-fructofuranosidase has a different autolytic-release pattern from its counterpart in
S. cerevisiae
. Also, high concentrations of glucose do not repress the
S. rouxii
enzyme. The β-fructofuranosidase in young cells of
S. rouxii
must be enclosed by the protoplasmic membrane or a special vesicular structure. This system was compared with other
Saccharomyces
species in connection with the translocation of enzymes across the protoplasmic membrane.
Unimportance of Counterflux in the Energetics of “Downhill” Transport
Authors: Koch Arthur L.
Published: January 2020

Adam Kepes suggested that the cellular transport and hydrolysis of orthonitrophenyl-β-
d
-galactopyranoside is powered by the counterflux of the
d
-galactose resulting from β-galactosidase action within the cell. His explanation would rationalize the unique insensitivity of this galactoside transport to energy poisons such as azide. But contrary to the predictions of this hypothesis, (i) there is no initial large inhibition that progressively lessens as galactose is produced. This was shown with a double wavelength stopped-flow spectrophotometer developed to eliminate interference from turbidity transients. (ii) The azide sensitivity does not increase with an external concentration of galactose sufficient to reverse the thermodynamic gradient. (iii) Mutation in galactose utilization or growth on highly catabolite-repressing regimens did not increase the azide sensitivity, and induction of galactose transport and metabolism did not decrease azide sensitivity. It was found that Kepes measurements must have contained two artifacts. One is that the control rate of hydrolysis decreases with time as the dense cell suspension becomes anaerobic. The other is that azide causes turbidity changes for some time after its introduction. If the former is avoided by magnetic stirring and the latter by double wavelength spectrophotometry or controls without substrate, the inhibition is constant from the earliest time that can be measured. It is therefore concluded that energy-unstarved cells, exposed to azide, still have adequate energy reserves to couple to the downhill transport, although their potential is not adequate to drive accumulation against a concentration gradient.
Isolation and Composition of Oligosaccharide Cores from Endotoxins of Two
Serratia marcescens
Strains
Authors: Wang C. S. , Burns R. K. , Alaupovic P.
Published: January 2020

The oligosaccharide cores isolated from the acetic acid hydrolysates of endotoxins from
Serratia marcescens
08 and
Serratia marcescens
Bizio were analyzed for their sugar composition. The intact oligosaccharide core from
S. marcescens
08 consisted of 2-keto-3-deoxyoctonate,
d
-glycero-
d
-mannoheptose,
l
-glycero-
d
-mannoheptose,
d
-glucose,
d
-galactose, and
d
-glucosamine in a molar ratio of 2:1:5:3:1:3 and that from
S. marcescens
Bizio consisted of the same sugar components in a molar ratio of 2:1:5:5:1:2. This result indicates that endotoxins from
S. marcescens
genus may contain more than one structural type of oligosaccharide core. Both oligosaccharide cores also differ in their chemical compositions from cores of other
Enterobacteriaceae
.
Carotenoid Biosynthesis in
Rhodotorula glutinis
Authors: Hayman Ernest P. , Yokoyama Henry , Chichester Clinton O. , Simpson Kenneth L.
Published: January 2020

It was determined that lycopene could be cyclized directly by
Rhodotorula glutinis
. It was also shown the the temperature effect (i.e., increased β-carotene synthesis in response to lower incubation temperatures) in
R. glutinis
was controlled by changes in enzyme concentration.
Metabolic function and properties of 4-hydroxyphenylacetic acid 1-hydroxylase from Pseudomonas acidovorans
Authors: Hareland W A , Crawford R L , Chapman P J , Dagley S
Published: January 2020

The enzyme 4-hydroxyphenylacetate, NAD(P)H:oxygen oxidoreductase (1-hydroxylating) (EC 1.14.13 ...; 4-hydroxyphenylacetate 1-monooxygenase; referred to here as 4-HPA 1-hydroxylase) was induced in Pseudomonas acidovorans when 4-hydroxyphenylacetate (4-PHA) was utilized as carbon source for growth; homogentisate and maleylacetoacetate were intermediates in the degradation of 4-HPA. A preparation of the hydroxylase that was free from homogentisate dioxygenase and could be stored at 4 C in the presence of dithioerythritol with little loss of activity was obtained by ultracentrifuging cell extracts; but when purified 18-fold by affinity chromatography the enzyme became unstable. Flavin adenine dinucleotide and Mg2+ ions were required for full activity. 4-HPA 1-hydrocylase was inhibited by KCl, which was uncompetitive with 4-HPA. Values of Ki determined for inhibitors competitive with 4-HPA were 17 muM dl-4-hydroxymandelic acid, 43 muM 3,4-dihydroxyphenylacetic acid, 87 muM 4-hydroxy-3-methylphenylacetic acid, and 440 muM 4-hydroxyphenylpropionic acid. Apparent Km values for substrates of 4-HPA 1-hydroxylase were 31 muM 4-HPA, 67 muM oxygen, 95 muM reduced nicotinamide adenine dinucleotide (NADH); AND 250 muM reduced nicotinamide adenine dinucleotide phosphate (NADPH). The same maximum velocity was given by NADH and NADPH. A chemical synthesis is described for 2-deutero-4-hydroxyphenylacetic acid. This compound was enzymatically hydroxylated with retention of half the deuterium in the homogentisic acid formed. Activity as substrate or inhibitor of 4-HPA 1-hydroxylase was shown only by those analogues of 4-HPA that possessed a hydroxyl group substituent at C-4 of the benze nucleus. A mechanism is suggested that accounts for this structural requirement and also for the observation that when 4-hydroxyphenoxyacetic acid was attacked by the enzyme, hydroquinone was formed by release of the side chain, probably as glycolic acid. Only one enantiometer of racemic 4-hydroxyhydratropic acid was attacked by 4-HPA 1-hydroxylase; the product, alpha-methylhomogentisic acid (2-(2,5-dihydroxyphenyl)-propionic acid), exhibited optical activity. This observation suggests that, during its shift from C-1 to C-2 of the nucleus, the side chain of the substrate remains bound to a site on the enzyme while a conformational change of the protein permits the necessary movement of the benzene ring.
Ultrastructure of Chlamydomonas eugametos palmelloids induced by chloroplatinic acid treatment
Authors: Nakamura K , Bray D F , Wagenaar E B
Published: January 2020

Palmelloids induced in the unicellular green alga Chlamydomonas eugametos by chloroplatinic acid treatment have been studied electron microscopically. Thin-sectioned specimens revealed the multilayer nature of the cell walls after second division within the palmelloid. Although synchrony in cell division is lost, to a certain degree, within the palmelloid, the cells themselves appeared normal, and the presence of normal flagellar structure was confirmed. The presence of the eyespot was observed at the optical level as well as in the freeze-etched specimens. The above results support the hypothesis that the palmelloid condition of Chlamydomonas eugametos induced by chloroplatinic acid is due to an abnormality in cell wall formation rather than flagellar malfunction or loss.
Energetics of Bacillus stearothermophilus growth: molar growth yield and temperature effects on growth efficiency
Authors: Coultate T P , Sundaram T K
Published: January 2020

The major growth yield of a prototrophic strain of Bacillus stearothermophilus under aerobic conditions on salts medium containing ammonium nitrate as the nitrogen source and glucose or succinate as the carbon source was maximal at the lowest growth temperature employed and decreased steadily as the temperature was raised. The temperature optima for growth yield and for growth rate were thus different. The molar growth yield values of the thermophile, especially at the lower growth temperatures, were similar to those reported for aerobically grown mesophilic bacteria, both on glucose and on succinate. At the higher growth temperatures, a lower proportion of glucose carbon was incorporated into cells and a correspondingly greater proportion was left incompletely utilized in the medium, mostly as acetate. This suggests a greater inefficiency in the coordination of the nonoxidative and oxidative phases of glucose metabolism at the gigher temperatures. Another factor causing a decreased cell yield at higher temperatures was possibly an uncoupling of energy production from respiration. The rates of respiration by intact cells of the thermophile on glucose and on succinate followed the Arrhenius relationship from 55 C to 20 C, which is some 20 C below the minimal growth temperature of the organism. The Arrhenius constant was 17.1 kcal/mol for glucose oxidation and 13.5 kcal/mol for succinate oxidation. These results are comparable to those reported for some mesophiles, and they suggest that the inability of the thermophile to grow at temperatures below about 41 C is not due to an abnormally high temperature coefficient for the uptake and oxidation of the carbon source.
Properties of Bacillus subtilis mutants temperature sensitive in germination
Authors: Galizzi A , Siccardi A G , Albertini A M , Amileni A R , Meneguzzi G , Polsinelli M
Published: January 2020

A new mutant of Bacillus subtilis defective in the outgrowth phase of spore germination has been isolated. When incubated at 46 C, the spores of the mutant gave rise to abnormally large swollen cells. Genetic crosses show that the mutant is different from the three previously described. The genetic analysis indicates two regions of the B. subtilis chromosome involved in the control of the spore outgrowth.
Comparison of Two Ferredoxins from
Rhodospirillum rubrum
as Electron Carriers for the Native Nitrogenase
Authors: Yoch Duane C. , Arnon Daniel I.
Published: January 2020

In coupling the reducing power of illuminated chloroplasts to the nitrogenase from photosynthetically grown
Rhodospirillum rubrum
cells, one of the native ferredoxins. FdI, was found to be three times more effective than FdII.
Anaerobic cytochrome b1 in Escherichia coli: association with and regulation of nitrate reductase
Authors: MacGregor C H
Published: January 2020

Nitrate reductase solubilized from the membrane of Escherichia coli by alkaline heat treatment was purified to homogeneity and used to prepare specific antibody. Nitrate reductase, precipitated by this antibody from Triton extracts of the membrane, contained a third subunit, not present in the purified enzyme used to prepare the antibody. This third subunit was identified as the cytochrome b1 apoprotein. This cytochrome is bound to nitrate reductase from wild-type E. coli in a ratio of 2 mol of cytochrome per mol of enzyme complex. In mutants unable to synthesize heme, this cytochrome b1 apoprotein is not bound to nitrate reductase. In these same mutants, the enzyme is overproduced and accumulates in the cytoplasm. The absence of cytochrome also affects the stability of the membrane-bound form of the enzyme.
Effects of methotrexate on intraperiplasmic and axenic growth of Bdellovibrio bacteriovorus
Authors: Pritchard M A , Langley D , Rittenberg S
Published: January 2020

The intraperiplasmic growth rate and cell yield of wild-type Bdellovibrio bacteriovorus 109J, growing on Escherichia coli of normal composition as the substrate, were not markedly inhibited by 10-3 M methotrexate (4-amino-N10-methylpteroylglutamic acid). In contrast, the growth rate and cell yield of the mutant 109Ja, growing axenically in 0.5% yeast extract +0.15% peptone, were strongly inhibited by 10-4 and 10-3 M methotrexate. Thymine, thymidine, and thymidine-5'-monophosphate, in increasing order of effectiveness, partially or completely reversed the inhibition. E. coli depleted of tetrahydrofolate and having an abnormally high protein/deoxyribonucleic acid (DNA) ratio was obtained by growing it in the presence of methotrexate. B. bacteriovourus grew at a normal rate on these depleted E. coli cells but with somewhat reduced cell yield. Mexthotrexate (10-3 M) inhibited intraperiplasmic growth of bdellovibrio on the depleted E. coli somewhat more than it inhibited growth on normal E. coli, but the effects were small compared with inhibition of axenic growth of the mutant. Total bdellovibrio DNA after growth on the depleted E. coli in the presence or absence of methotrexate exceeded the initial quanity of E. coli DNA present. Thymidine-5'-monophosphate (10-3 M) largely reversed the inhibition and increased the amount of net synthesis of DNA. The data are consistent with the prediction that intraperiplasmic growth of B. bacteriovorus should be insensitive to all metabolic inhibitors that act by specifically preventing synthesis of essential monomers. The data also indicate that B. bacteriovorus possesses thymidylate synthetase, thymidine phosphorylase, and thymidine kinase, and has the potential to carry out de novo DNA synthesis from non-DNA precursors during intraperiplasmic growth. The results also suggest that methionyl tRNAfMet is not required for initiation of protein synthesis by B. bacteriovorus.
Energy efficiency of intraperiplasmic growth of Bdellovibrio bacteriovorus
Authors: Rittenberg S C , Hespell R B
Published: January 2020

The Y-ATP (energy efficiency) of intraperiplasmic growth of Bdellovibrio bacteriovorus was determined from the distribution of radioactivity of the substrate organism ([U-14C]Escherichia coli) btween CO2 and bdellovibrio cells at the end of growth. A "best" Y-ATP value of 18.5 was obtained from single growth cycle experiments and an average value of 25.9 from multicycle experiments. Both values are much higher than the usual value of 10.5 for bacteria growing in rich media. The bases for the unusual energy efficiency for growth of B. bacteriovorus are discussed.
Degradative acetolactate synthase of Bacillus subtilis: purification and properties
Authors: Holtzclaw W D , Chapman L F
Published: January 2020

A degradative acetolactate synthase (acetolactate pyruvate-lyase [carboxylating], EC 4.1.3.18) from Bacillus subtilis has been partially purified and characterized. The synthesis of the enzyme was induced by growth of cells in minimal medium plus isobutyrate or acetate. The enzyme was partially purified by ammonium sulfate fractionation, gel filtration, and hydroxyapatite chromatography. The pH optimum of the purified enzyme was 7.0 in phosphate buffer. When assayed in phosphate buffer (pH 7.0), activity was stimulated by acetate and inhibited by sulfate. When assayed in acetate buffer (pH 5.8), activity was inhibited both by sulfate and phosphate. Michaelis-Menten kinetics was observed when the enzyme was assayed in phosphate buffer (pH 6.0 or 7.0), and inhibition by sulfate was competitive and activation by acetate was noncompetitive. When assayed in acetate buffer (pH 5.8), nonlinear Lineweaver-Burk plots were obtained; inhibition by phosphate appeared to be competitive and that by sulfate was of the mixed type. The approximate molecular weight of the purified enzyme was 250,000 as determined by gel filtration.
Bacteriophage resistance in Escherichia coli K-12: general pattern of resistance
Authors: Hancock R E , Reeves P
Published: January 2020

Resistant mutants were isolated to 42 virulent bacteriophages in one strain of Escherichia coli K-12 and tested for resistance or sensitivity to a set of 56 bacteriophages. Most of the mutants fell into 11 groups with respect to their resistance patterns. It was possible to classify the bacteriophages broadly, according to the variety of mutants that were resistant to them.
Sexal reproductive cycle of Monascus in submerged shaken culture
Authors: Carels M , Shepherd D
Published: January 2020

A strain of Monascus was grown in submerged, shaken culture using a glucose-salts mediumn. The formation of ascospores was studied by microscopic examination of samples taken at regular intervals for 6 days. All the stages of sexual reproduction previously described for Monascus were observed. The unusual feature of the strain studied was that it produced sexual structures and cliestothecia of greatly varying sizes.
Myxospore induction in a nondispersed growing mutant of Myxococcus xanthus
Authors: Burchard R P
Published: January 2020

Myxococcus xanthus RB5, a rough-colony-forming, nondispersed growing mutant of strain FBt, forms macroscopic, multicellular masses of radially oriented cells in shake cultures. The cells appear to be held together by slime fibrils. Physical and enzymatic methods to disrupt the spheres were unsuccessful as were attempts to isolate dispersed growing mutants. During incubation of the spheres in starvation medium, the cells within convert to myxospores, indistinguishable from those formed in fruiting bodies. Myxospores were also induced in artifically constructed, dense masses of cells of a nonmotile strain.
Characterization of transmissible genetic elements from sucrose-fermenting Salmonella strains
Authors: Wohlhieter J A , Lazere J R , Snellings N J , Johnson E M , Synenki R M , Baron L S
Published: January 2020

Two of seven sucrose-fermenting Salmonella strains obtained from clinical sources were found capable of conjugal transfer of the sucrose fermentation (Scr+) property to the Escherichia coli K-12 strain WR3026. The genetic elements conferring this Scr+ property, designated scr-53 and scr-94, were then conjugally transmissible from Escherichia coli WR3026 Scr+ exconjugants to other strains of Escherichia coli at frequences of 5 times 10- minus 6 to 5 times 10- minus 3 for the scr-53 element and 10- minus 6 to 10- minus 5 for the scr-94 element. In Escherichia coli hosts, both of these elements were compatible with F-lac and with each of six previously characterized transmissible lac elements. No antibiotic resistance characteristics or colicin production were discovered to be associated with either scr-53 or scr-94. Neither scr element generated a male host response to the female-specific phage phiII, but the scr-53 element rendered its Escherichia coli host sensitive to the male-specific phage R-17. Escherichia coli hosts containing scr-53 were susceptible to lysis by P1vir, and transduction of the scr-53 element was accomplished with this phage. The scr-53 element was isolated from Escherichia coli WR3026, Scr+ transductants, and Escherichia coli WR2036 Scr+ exconjugants as a covalently closed circular deoxyribonucleic acid molecule with a molecular weight (determined by electron microscopy) of approximately 52 times 10-6. Receipt of the scr-94 element rendered Escherichia coli hosts of this element unsusceptible to lysis by P1vir, although adsorption of the phage by an Escherichia coli WR3026 exconjugant containing scr-94 occurred as efficiently as it did on WR3026 itself. Repeated examination of Escherichia coli strains harboring scr-94, as well as of the Salmonella strain which initially contained it, did not reveal the presence of circular deoxyribonucleic acid. The synthesis of the sucrose cleaving enzyme was inducible in Escherichia coli exconjugants containing either scr-53 or scr-94.
Photosynthetic sulfide oxidation by Chloroflexus aurantiacus, a filamentous, photosynthetic, gliding bacterium
Authors: Madigan M T , Brock T D
Published: January 2020

Chloroflexus, a newly described genus of filamentous, photosynthetic, gliding bacteria, oxidizes sulfide anaerobically under photoautotrophic or photoheterotrophic growh conditions and deposits elemental sulfur outside the cell. The formation of sulfur granules outside the cell supports the idea that this organism is related to the green sulfur bacteria (Chlorobiaceae).
Nature of the Suppressor of
Bacillus subtilis
HA101B
Authors: Shub David A.
Published: January 2020

The suppressor of
Bacillus subtilis
HA101B is shown to act by suppression of polypeptide chain termination. The efficiency of suppression is 25 to 30%.
Effect of Lysozyme on Ionic Forms of Spores of
Clostridium perfringens
Type A
Authors: Ando Yoshiaki
Published: January 2020

H spores of
Clostridium perfringens
type A (two strains) were more sensitive to germination by lysozyme than native spores. Resistance to lysozyme of H spores was restored by calcium loading.
A Third Kasugamycin Resistance Locus,
ksgC
, Affecting Ribosomal Protein S2 in
Escherichia coli
K-12
Authors: Yoshikawa Masanosuke , Okuyama Akira , Tanaka Nobuo
Published: January 2020

A third kasugamycin-resistant mutant affecting ribosomal protein S2 has been isolated from
Escherichia coli
K-12. Mating and transduction revealed that this newly recognized kasugamycin resistance locus, designated as
ksgC
, is located at 0.1 to 0.2 min from
purE
.
Specialized peptide transport system in Escherichia coli
Authors: Barak Z , Gilbarg C
Published: January 2020

Trileucine is utilized as a source of leucine for growth of strains of Escherichia coli K-12 that are deficient in the oligopeptide transport system (Opp). Trithreonine is toxic to E. coli K-12. Opp- mutants of E. coli K-12 retain complete sensitivity to this tripeptide. Moreover, E. coli W, which is resistant to trithreonine, can utlize this tripeptide as a threonine source and this capability is fully maintained in E. coli W (Opp-). A spontaneous trithreonine-resistant mutant of E. coli K-12 (Opp-) has been isolated that has an impaired growth response to trileucine and is resistant to trithreonine. Trileucine competes with the uptake of trithreonine as measured by its ability to relieve trithreonine toxicity in E. coli K-12. It is concluded that trileucine as well as trithreonine are transported into E. coli K-12 or W by a common uptake system that is distinct from the Opp system. Trimethionine can act as a competitor of trileucine or trithreonine-supported growth and as an antagonist of trithreonine toxicity in Opp- mutants. It is concluded that trimethionine is recognized by the trileucine-trithreonine transport system. Trithreonine, trimethionine, and trileucine are also transported by the Opp system, as they all relieve triornithine toxicity towards E. coli W and compete with tetralysine utilization as lysine source for growth of a lysine auxotroph of this strain.
Multiplicity of oligopeptide transport systems in Escherichia coli
Authors: Naider F , Becker J M
Published: January 2020

The ability of Escherichia coli K-12 4212 to utilize a variety of oligopeptides as sources of required amino acids was examined. Triornithine-resistant mutants of this strain were oligopeptide permease deficient (Opp-) as judged by their inability to utilize (Lys)3 and (Lys)4 as sources of lysine and their resistance to the toxic tripeptide (Val)3. These same mutants were able to grow when Met-Met-Met, Met-Gly-Met, Met-Gly-Gly, Gly-Met-Gly, Gly-Gly-Met, Gly-Met-Met, Met-Met-Gly, or Leu-Leu-Leu were supplied in place of the requisite amino acid. The system mediating the uptake of these peptides, herein designated Opr I, was not able to transport N-alpha-acetylated peptides, nor the tetrapeptides Met-Gly-Met-Met, Met-Met-Gly-Met, or Met-Met-Met-Gly. Competition experiments indicated that trimethionine and trileucine enter E. coli K-12 via either Opp or Opr I. Analogous results were found using the methionine, leucine-requiring auxotroph E. coli B163. It appears that more than one oligopeptide transport system exists in E. coli and that the system mediating peptide uptake is complex.
Facilitated transport of calcium by cells and subcellular membranes of Bacillus subtilis and Escherichia coli
Authors: Silver S , Toth K , Scribner H
Published: January 2020

The level of calcium in growing cells is lower than that in the growth medium. Non-energy-dependent uptake of 45-Ca by log-phase cells of Bacillus subtilis occurs under two conditions: at 0 C or in the presence of m-chlorophenyl carbonylcyanide hydrazone. Similar uptake, but quantitatively less, occurs with Escherichia coli cells under the same conditions. Membrane vesicles prepared from B. subtilis or E. coli accumulate 45-Ca by a process that does not depend on added energy sources and is not inhibited by the respiratory poison cyanide. The properties of calcium transport in all cases is consistent with carrier-mediated, facilitated transport with specificity Ca-2+ greater than Sr-2+ greater than Mn-2+ greater than Mg-2+. Upon transfer of cells from 0 C to 20 C, pre-accumulated 45-Ca is released. Heat-killed cells do not accumulate 45-Ca and calcium is released by cells upon addition of toluene (under conditions that do not cause visible lysis). These results suggest that the facilitated uptake of calcium may be utilizing a transport system that normally is responsible for the energy-dependent excretion of calcium from the cells.
Genetics of resistance to colicins in Escherichia coli K-12: cross-resistance among colicins of group A
Authors: Davies J K , Reeves P
Published: January 2020

By using each of the available colicins, we have isolated a large number of colicin-resistant mutants. They included both receptor and tolerant mutants and each was screened for cross-resistance to all other colicins. On the basis of the cross-resistance of these mutants it was possible to place known colicins into two mutually exclusive groups, group A and group B. Mutants selected as resistant to colicins of group A may or may not be cross-resistant to other colicins of group A, BUT Are never resistant to colicins of group B. The reverse also applies. The mutants isolated as resistant to colicins of group A (A, E1, E2, E3, K, L, N, S4, and X) have been divided into 21 phenotypic classes on the basis of their colicin resistance patterns. These include most of the tolerant and receptor mutants previously isolated, some of which were previously shown to also have an increased sensitivity to certain antibiotics and detergents. Type strains from each of the phenotypic classes were therefore tested for sensitivity to a range of antibiotics, detergents, and surfactants that included all those previously used. With these new data, it has been possible to speculate informatively on the mode of action of the different colicins. We have confirmed the position of previously isolated mutations on the Escherichia coli K-12 genetic map, and located approximately the loci conferring colicin resistance in some of the newly isolated mutants.