bluuebunny/crossref_metadata_2025 huggingface dataset:
Physiological Studies of Methane- and Methanol-Oxidizing Bacteria: Immunological Comparison of a Primary Alcohol Dehydrogenase from
Methylococcus capsulatus
and
Pseudomonas
sp. M27
Authors: Patel R. N. , Mandy W. J. , Hoare D. S.
Published: January 2020

A primary alcohol dehydrogenase was purified from cell extracts of two apparently unrelated microorganisms, namely,
Pseudomonas
sp. M27 and
Methylococcus capsulatus
. Rabbit antiserum prepared against the purified enzyme from
M. capsulatus
revealed distinctive antigenic determinants by quantitative and gel precipitin reactions. Rabbit antiserum to M27 enzyme detected both distinctive and shared antigenic determinants. Certain methane- and methanol-oxidizing bacteria were grouped on the basis of serological cross-reacting enzyme specificities.
Temperature-Sensitive Divisionless Mutant of
Bacillus subtilis
Defective in the Initiation of Septation
Authors: Breakefield Xandra O. , Landman Otto E.
Published: January 2020

A temperature-sensitive divisionless mutant of
Bacillus subtilis
168,
tms-12
, is shown to be defective in an early step in septum formation at the restrictive temperature. The nature of this defect has been studied by comparing the growth and composition of mutant and wild-type (
tms-12
+
) cells at the restrictive (48 C) and permissive (34 C) temperatures. At 48 C,
tms-12
cells grow as nonseptate, multinucleate filaments. Filamentation does not appear to be a result of alterations in properties of the cell wall, since the ratio of mucopeptide to teichoic acid, the autolytic activity, and the ability of the walls to protect cells against osmotic shock are comparable in
tms-12
filaments and
tms-12
+
bacilli grown at 48 C. Synthesis of deoxyribonucleic acid and the segregation of nucleoids also proceed normally during filamentation. The synthesis of membrane, however, is delayed during filamentation of
tms-12
. No gross alterations were observed in the protein or lipid composition of membranes isolated from mutant filaments. Septum formation resumes when filaments are returned to 34 C and appears to be associated with an increased synthesis of membrane. The occurrence of septa was monitored both by microscopic observation of cross walls and by assays of the number of viable protoplasts released from bacillary filaments upon removal of the cell wall. Septation recovery can be blocked by inhibitors of ribonucleic acid and protein synthesis added during, but not after, the first 7 min of recovery at 34 C. By contrast, inhibition of deoxyribonucleic synthesis does not block recovery.
Sequential Metabolic Events During Encystment of
Azobacter vinelandii
Authors: Hitchins V. M. , Sadoff H. L.
Published: January 2020

Cells of
Azotobacter vinelandii
are specifically induced to encyst by β-hydroxybutyrate (BHB). The process of differentiation, which occurs over a period of 36 h, was characterized by an ordered sequence of biochemical events. Upon initiation of encystment, nitrogen fixation and glucose-6-phosphate dehydrogenase activities decreased immediately to very low levels. This was followed by an increase in the specific activities of BHB dehydrogenase, isocitrate dehydrogenase, isocitrate lyase, and malate synthase first at 3 h and then again at 21 h. The peak activity of fructose 1,6-diphosphate aldolase occurred at 6 h, and the enzyme activity then decreased gradually. Fructose 1,6-diphosphatase had peak activities at 9 and 27 h. Deoxyribonucleic acid synthesis ceased just prior to the final cell division at 4 to 6 h, but ribonucleic acid synthesis continued until the 12th h. From labeling studies and the appearance of new enzyme activities, it appeared that protein synthesis continued throughout encystment.
Tryptophan Biosynthetic Enzymes of
Staphylococcus aureus
Authors: Proctor Alan R. , Kloos Wesley E.
Published: January 2020

Tryptophan biosynthetic enzymes were assayed in various tryptophan mutants of
Staphylococcus aureus
strain 655 and the wild-type parent. All mutants, except
trpB
mutants, lacked only the activity corresponding to the particular biosynthetic block, as suggested previously by analysis of accumulated intermediates and auxonography. Tryptophan synthetase A was not detected in extracts of either
trpA
or
trpB
mutants but appeared normal in other mutants. Mutants in certain other classes exhibited partial loss of another particular tryptophan enzyme activity. Tryptophan synthetase B activity was not detected in cell extract preparations but was detected in whole cells. The original map order proposed for the
S. aureus
tryptophan gene cluster was clarified by the definition of
trpD
(phosphoribosyl transferase
−
) and
trpF
(phosphoribosyl anthranilate isomerase
−
) mutants. These mutants were previously unresolved and designated as
trp
(
DF
) mutants (anthranilate accumulators). Phosphoribosyl anthranilate isomerase and indole-3-glycerol phosphate synthetase enzymes were separable by molecular sieve chromatography, suggesting that these functions are coded by separate loci. Molecular sieve chromatography failed to reveal aggregates involving anthranilate synthetase, phosphoribosyl transferase, phosphoribosyl anthranilate isomerase, and indole-3-glycerol phosphate synthetase, and this procedure provided an estimate of the molecular weights of these enzymes. Tryptophan was shown to repress synthesis of all six tryptophan biosynthetic enzymes, and derepression of all six activities was incident upon tryptophan starvation. Tryptophan inhibited the activity of anthranilate synthetase, the first enzyme of the pathway.
Fatty Acid Activation by a Lipophilic Bacterium
Authors: Calmes Robert , Deal S. J.
Published: January 2020

Cell-free extracts ofNocardia asteroidesactivated saturated fatty acids from octanoate to octadecanoate, plus docosanoate; maximal activation occurred with dodecanoate. No activation of short-chain fatty acids was observed. The activating enzyme, characterized as an acyl-coenzyme A (Co A) synthetase (acid: Co A ligase [adenosine monophosphate]; EC 6.2.1.3), was localized in the cytoplasm of the cells and had absolute requirements for Co A, adenosine 5′-triphosphate, and Mg2+. Kinetic data suggested thatN. asteroidespossessed at least two synthetases: one specific for short-chain fatty acids, and the other specific for medium- and long-chain fatty acids.
Effects of Temperature Variation on the Fatty Acid Composition of a Psychrophilic
Candida
Species
Authors: McMurrough I. , Rose A. H.
Published: January 2020

During the batch cultivation of a psychrophilic
Candida
species, the proportions of oleic and linolenic acid esters in the cells underwent a cyclic variation regardless of the incubation temperature.
Acriflavine Uptake and Resistance in
Serratia marcescens
Cells and Spheroplasts
Authors: Woods D. R. , Schauder Valerie R. , Waddington Penelope B.
Published: January 2020

Acriflavine uptake and resistance were investigated in red, sensitive
Serratia marcescens
cells and in orange, resistant mutant cells and their respective spheroplasts. Acriflavine-sensitive cells bound more acriflavine than acriflavine-resistant cells. Spheroplasts from sensitive and resistant cells were both resistant to and bound similar amounts of acriflavine. Sensitive cells were resistant to acriflavine in medium supplemented with 0.01 M MgSO
4
and 0.5 M sucrose. In the presence of 0.01 M MgSO
4
and 0.5 M sucrose, acriflavine binding by sensitive cells was reduced to the level of binding by resistant cells. Inhibition of metabolism by carbon starvation, chloramphenicol, As
2
O
3
, nitrosoguanidine, and bromouracil did not affect the uptake of acriflavine by sensitive and resistant cells. Rapid temperature changes did not alter the acriflavine-binding capacity of the cells, and no temperature dependence of acriflavine uptake or release was observed at 0 and 30 C. Acriflavine uptake by both sensitive and resistant cells increased with increase in pH from 5.7 to 8.0. The logarithm of acriflavine uptake was a linear function of the logarithm of the acriflavine concentration in the binding medium.
Factors Affecting Cellulolysis by
Ruminococcus albus
Authors: Smith W. R. , Yu Ida , Hungate R. E.
Published: January 2020

The factors influencing the digestion of pebble-milled cellulose by enzymes were studied by using several strains of
Ruminococcus albus
including a mutant characterized by a more eccentric location of its colony in the clearing produced by digestion of the cellulose in the thin layer lining the wall of a culture tube. Most of the cellulase is extracellular. As much as 65% of the cellulose could be digested by the cell-free enzymes provided the quantity of cellulose was small. Fresh enzyme was repeatedly administered or the digestion experiment was arranged in a dialysis bag through which digestion products could diffuse. Cellobiose and, to a lesser extent, glucose inhibited digestion. Pebble-milled filter paper, moist crystalline cellulose from cotton, and dry crystalline cellulose (Sigmacel) were digested, but in decreasing rapidity, respectively. Carboxymethylcellulose was digested more rapidly than pebble-milled cellulose but to approximately the same final extent as judged by Cu reduction values. Cell walls from alfalfa were digested. The enzyme preparation was active over the pH range 6.0 to 6.8 and showed most rapid cellulose digestion at 45 C. Part of the cellulolytic activity was irreversibly destroyed by exposure to oxygen. Much of the enzyme was absorbed on cellulose. The absorption and desorption characteristics, as well as the partial inhibition by oxygen, indicate that multiple enzymes are involved.
Fermentation of Glucose, Fructose, and Xylose by
Clostridium thermoaceticum
: Effect of Metals on Growth Yield, Enzymes, and the Synthesis of Acetate from CO
2
Authors: Andreesen Jan R. , Schaupp Annabella , Neurauter Chris , Brown Ann , Ljungdahl Lars G.
Published: January 2020

Clostridium thermoaceticum
ferments xylose, fructose, and glucose with acetate as the only product. In fermentations with mixtures of the sugars, xylose is first fermented, then fructose, and last, glucose. Fructose inhibits the fermentation of glucose, and this inhibition appears to be due to a repression of the synthesis of an enzyme needed for glucose utilization. Addition of metals to the culture medium increases the cell yield drastically from about 7 to 18 g per liter, and Y(glucose) values between 40 and 50 are obtained. According to the postulated pathways of the fermentation of glucose and synthesis of acetate from CO
2
by
C. thermoaceticum
, 3 mol of ATP are available as energy for growth. Thus a Y(adenosine 5′-triphosphate) of 13 to 16 is obtained. Because the normal Y(ATP) value is 10.5, this could mean that an additional source of ATP is available by an unknown mechanism. The addition of metals also increases the nicotinamide adenine dinucleotide phosphate-dependent formate dehydrogenase activity, the overall reaction (
14
CO
2
→ acetate), and the incorporation of the methyl group of 5-methyltetrahydrofolate into acetate. These reactions are catalyzed very efficiently by cells harvested in early growth, whereas cells obtained at the end of a fermentation have very low formate dehydrogenase activity and capacity to incorporate CO
2
into acetate. The following enzymes involved in the synthesis of acetate from CO
2
and in the metabolism of pyruvate are present in extracts of
C. thermoaceticum
: 10-formyltetrahydrofolate synthetase, 5,10-methenyltetrahydrofolate cyclohydrolase, 5,10-methylenetetrahydrofolate dehydrogenase, 5,10-methylenetetrahydrofolate reductase, phosphate acetyltransferase, and acetate kinase. These enzymes are not or are very little affected by the addition of metals to the growth medium.

The amount of corrinoids in cells from early growth is low, whereas it is high in cells harvested late in growth. The opposite is found for the activity of δ-aminolevulinate dehydratase, which is high at the beginning of growth and low at the end.
Adenine Nucleotide Levels in
Neurospora
, as Influenced by Conditions of Growth and by Metabolic Inhibitors
Authors: Slayman Clifford L.
Published: January 2020

By a combination of luciferase and fluorescence methods adenine nucleotide pools in
Neurospora crassa
have been examined under various conditions of growth and metabolic inhibition. During sustained exponential growth (25 C, shaking liquid cultures), the intracellular adenosine 5′-triphosphate (ATP) concentration, [ATP]
i
, rises slowly from the conidial level near 1 mM (1 mmol/kg of cell water) to a maximum of 2.0 to 2.5 mM at 14 h, after which it slowly declines. The adenosine 5′-diphosphate and adenosine 5′-monophosphate (AMP) curves show two peaks, at 8 and 20 h, with a minimum at 16 h. The “energy charge” function varies around a mean of 0.72 throughout the period of exponential growth. Transferral of growing cells to buffer lacking a nitrogen source stabilizes the [ATP]
i
near 2.5 mM, apparently independent of the cell age, and most studies of metabolic inhibitors were carried out on cells grown 14 to 16 h and then shifted to N-free buffer. Under these conditions sudden respiratory blockade (cyanide) produces exponential decay of ATP with a time constant of about 5.7 s (half-time of 3.9 s), and at a rate which implies a minimal ATP turnover of 0.44 mM/min. This figure is about one-third the rate (1.17 mM/min) which would be calculated from steady-state respiration, a discrepancy which may partly be accounted for by transphosphorylation from appreciable amounts of non-adenine nucleoside di- and triphosphates present in
Neurospora
. For all three adenine nucleotides, the transients associated with sudden respiratory blockade include overshoots or undershoots of several minutes duration, which are consistent with feedback regulation of glycolysis by the AMP/ATP ratio.
Inhibition of Formation ofEscherichia coliMating Pairs by f1 and MS2 Bacteriophages as Determined with a Coulter Counter
Authors: Ou Jonathan T.
Published: January 2020

The effect of male-specific filamentous deoxyribonucleic acid (f1) and isometric ribonucleic acid (MS2) bacteriophages on the formation of mating pairs inEscherichia coliconjugation was examined directly in the Coulter counter. When a sufficient multiplicity of infection (MOI) was used, the f1 phage immediately and completely inhibited the formation of mating pairs. On the other hand, the MS2 phage at a relatively high MOI also inhibited the formation of mating pairs significantly although not completey. The inhibitory effect of MS2 phage was dependent on the time of addition and the MOI used. At relatively low MOI (<20), the MS2 phage showed some inhibitory effect when added to a male culture prior to mixing with females, whereas no effect was observed when phages were added after mating pair formation had already commenced. At a high MOI (>400) MS2 phage disrupted the mating pairs already formed. Some preformed mating pairs were resistant to the high MOI of MS2 phages, however, and the “sensitive” (to high MOI) mating pairs seem to mature into “resistant” mating pairs as a function of time. We conclude that the tip of an F pilus is the specific attachment site for mating. The following process of mating pair formation has been formulated by deduction. (i) The sides of F pili weakly contact female cells, (ii) then the tips of F pili attach to the specific receptor sites to form initial mating pairs, and (iii) those pairs mature into mating pairs that are resistant to the high MOI of MS2 phages. The high MOI of MS2 prevents the first step, whereas f1 phages affect the second step—the binding between the tips of F pili and the receptor sites.
Temperature-Sensitive Mutants for the Replication of Plasmids in
Escherichia coli
: Requirement for Deoxyribonucleic Acid Polymerase I in the Replication of the Plasmid ColE
1
Authors: Kingsbury David T. , Helinski Donald R.
Published: January 2020

An
Escherichia coli
mutant (
polA1
), defective in deoxyribonucleic acid (DNA) polymerase I, (EC 2.7.7.7) is unable to maintain colicinogenic factor E1 (ColE1), whereas several sex factor plasmids are maintained normally in this strain.
polA1
mutant strains containing these sex factor plasmids do not exhibit a readily detectable plasmid-induced polymerase activity. A series of
E. coli
mutants that are temperature sensitive for ColE1 maintenance, but able to maintain other plasmids, were isolated and shown to fall into two phenotypic groups. Mutants in one group are defective specifically in ColE1 maintenance at 43 C, but exhibit normal DNA polymerase I activity. Mutations in the second group map in the
polA
gene of
E. coli
, and bacteria carrying these mutations are sensitive to methylmethanesulfonate (MMS). Revertants that were selected either for MMS resistance or the ability to maintain ColE1 were normal for both properties. The DNA polymerase I enzyme of two of these mutants shows a pronounced temperature sensitivity when compared to the wild-type enzyme. An examination of the role of DNA polymerase I in ColE1 maintenance indicates that it is essential for normal replication of the plasmid. In addition, the presence of a functional DNA polymerase I in both the donor and recipient cell is required for the ColV-promoted conjugal transfer of ColE1 and establishment of the plasmid in the recipient cell.
Isolation and Characterization of Plasmid Deoxyribonucleic Acid from
Streptococcus mutans
Authors: Dunny G. M. , Birch N. , Hascall G. , Clewell D. B.
Published: January 2020

A small plasmid with a molecular weight of approximately 3.0 × 10
6
and present to the extent of about 16 copies per chromosomal genome equivalent was isolated from
Streptococcus mutans
strain LM-7.
Fatty Acids of
Myxococcus xanthus
Authors: Ware Judith C. , Dworkin Martin
Published: January 2020

Fatty acids were extracted from saponified vegetative cells and myxospores of
Myxococcus xanthus
and examined as the methyl esters by gas-liquid chromatography. The acids consisted mainly of C
14
to C
17
species. Branched acids predominated, and
iso
-pentadecanoic acid constituted half or more of the mixture. The other leading component (11–28%) was found to be 11-
n
-hexadecenoic acid. Among the unsaturated acids were two diunsaturated ones, an
n
-hexadecadienoic acid and an
iso
-heptadecadienoic acid. No significant differences between the fatty acid compositions of the vegetative cells and myxospores could be detected. The fatty acid composition of
M. xanthus
was found to be markedly similar to that of
Stigmatella aurantiaca
. It is suggested that a fatty acid pattern consisting of a large proportion of
iso
-branched C
15
and C
17
acids and a substantial amount of an
n
-16:1 acid is characteristic of myxobacteria.
Plasmid in
Bacillus pumilus
and the Enhanced Sporulation of Plasmid-Negative Variants
Authors: Lovett Paul S.
Published: January 2020

Approximately 3% of the deoxyribonucleic acid (DNA) of
Bacillus pumilus
NRS576 can be isolated as covalently closed, circular duplex molecules of homogeneous size. The mol wt of the 576 plasmid is approximately 30 million. NRS576 (plasmid
+
) is oligosporogenic; less than 1% of the cells form spores during incubation in liquid AK sporulation medium. Variants that form spores at a high frequency (greater than 50% spores in 24 h) occur spontaneously at a frequency of approximately 10
−5
. More than 25 such variants have been examined and all lack detectable plasmid DNA. A relationship appears to exist between the oligosporogenic properties of NRS576 and the presence of the 576 plasmid.
Genetic and Biochemical Investigation of the
Escherichia coli
Mutant
hfl-1
Which is Lysogenized at High Frequency by Bacteriophage Lambda
Authors: Belfort Marlene , Wulff Daniel L.
Published: January 2020

The
Escherichia coli
mutant
hfl-1
is lysogenized at very high frequency by bacteriophage lambda. The normal requirement for the λ
c
III gene product in the establishment of repression is not observed in
hfl-1
strains. These phenotypic characteristics are specified by a single locus at 82.5 min on the
E. coli
map in extremely close proximity to the
purA
gene, cotransduction frequencies ranging from 97 to 100% depending on the particular
purA
marker used. The lactose operon is shown to function normally in this strain, and there are also no demonstrable differences in ribonucleic acid polymerase activity or cyclic-adenosine monophosphate levels. Alterations in the cell envelope are indicated by a slight rifamycin resistance, which is reversible by pretreating the cells with ethylenediaminetetraacetic acid, and by a resistance to penicillin and a sensitivity to high concentrations of sodium dodecyl sulfate. It is not known whether this change in cell surface is the primary lesion, or a pleiotropic effect of some more basic metabolic shift.
Cell Division in Yeasts: Movement of Organelles Associated with Cell Plate Growth of
Schizosaccharomyces pombe
Authors: Johnson Byron F. , Yoo Bong Y. , Calleja G. B.
Published: January 2020

Electron microscopy of dividing fission yeast cells shows establishment of an annular rudiment (AR) of electron-transparent material under the old cell wall as the first sign of elaboration of the cell plate. The AR grows centripetally, finally closing at the mid-point of the cell. During the inward growth of the AR it is thickened by addition of denser material which becomes the scar plug after fission; the electron-transparent material is lost at fission. Lying always between the cytoplasmic membrane and the cell wall is a dark layer of variable thickness. This layer becomes markedly thickened into a fillet at the base of the centripetally growing cell plate. The fission process begins after the cell plate is completely elaborated. One striking feature of fission is the migration of dense material from the fillet at the base of the cell plate outwardly through the matrix of the cell wall to its final resting place as a dark ring, a “fuscannel,” adjacent to the fission scar. The inclusion of Golgi bodies in many sections suggests their involvement in cell plate elaboration, presumably through production of the dense bodies which are seen to fuse with the dark layer proximal to the growing cell plate.
Loss of Photosynthetic Activity in Two Blue-Green Algae as a Result of Osmotic Stress
Authors: Grodzinski B. , Colman Brian
Published: January 2020

A progressive loss of photosynthetic activity occurred when cells ofAnacystis nidulansandCoccochloris peniocystiswere incubated in increasing concentrations of osmotica from 0.2 to 0.7 M, and there was a release of pteridine from the cells proportional to the loss of photosynthetic activity.
Studies on Acetyl-Coenzyme A Synthetase of Yeast: Inhibition by Long-Chain Acyl-Coenzyme A Esters
Authors: Satyanarayana T. , Klein Harold P.
Published: January 2020

Long-chain acyl-coenzyme A (CoA) compounds (palmityl, stearyl, and oleyl) were found to be potent inhibitors of acetyl-CoA synthetase (ACS) of
Saccharomyces cerevisiae
strain LK2G12 from aerobic, but not from nonaerobic, cells. The effectiveness of the inhibitors of the aerobic enzyme was in the following order: palmityl-CoA < stearyl-CoA < oleyl-CoA. Short-chain acyl-CoA compounds (propionyl, butyryl, and valeryl) and long-chain fatty acids had no effect on ACS from either source. The inhibition by oleyl-CoA was found to be dependent on enzyme concentration, whereas the inhibition by palmityl- and stearyl-CoA was independent of ACS concentration. Inhibition by palmityl-CoA was noncompetitive with respect to both acetate and CoA, and with increasing concentration of inhibitor the pattern was sigmoidal, with a Hill value of 3.24. At maximally inhibitory concentrations of palmityl-CoA, a small amount of enzyme activity remained. This noninhibitable enzyme in aerobic cells was shown not to be of nonaerobic origin.
Interactions of Group H Resistance Factors with the F Factor
Authors: Smith H. R. , Grindley N. D. F. , Humphreys G. O. , Anderson E. S.
Published: January 2020

The four R factors described in this paper form a single compatibility group which has been previously designated group H. Recombination was demonstrated between any pair of the plasmids TP117, 123, and 124. In contrast, TP116 did not appear to recombine with any other members of the group. TP117, 123, and 124 usually displaced the F factor fromEscherichia coliK-12F+, while TP116 and F coexisted stably in that strain. Deoxyribonucleic acid reassociation experiments showed minimal homology between F and the four group H plasmids. The results indicate that there are limitations to using incompatibility alone for classification of bacterial plasmids.
Morphology of Bacteriophage-Like Particles from
Desulfovibrio vulgaris
Authors: Handley Joan , Adams Verna , Akagi J. M.
Published: January 2020

Phagelike particles obtained from a mitomycin C-induced lysate of
Desulfovibrio vulgaris
are described. Whether they can be classified as temperate bacteriophages or as bacteriocins has not been determined.
Genetics and Physiology of atolEMutant ofEscherichia coliK-12 and Phenotypic Suppression of Its Phenotype by Galactose
Authors: Eriksson-Greenberg Kerstin G. , Nordström Kurt
Published: January 2020

ThetolEmutation causes tolerance to colicins E2 and E3 as well as other effects on the phenotype ofEscherichia coliK-12. The lipopolysaccharide of the mutant shows a reduction in the content of galactose, glucose, and rhamnose. The phenotype of the mutant, including the composition of the lipopolysaccharide, is suppressed by galactose. The map position is shown by the gene ordertrp-purB-tolE-tolD-galKETO.
Pyrimidine Metabolism in
Acinetobacter calcoaceticus
Authors: Øvrebø Steinar , Kleppe Kjell
Published: January 2020

The metabolism of thymine, thymidine, uracil, and uridine has been investigated in five different strains of
Acinetobacter calcoaceticus
. Attempts to isolate thymine and thymidine auxotrophic mutants were not successful. Consistent with this finding was the observation that uptake of radioactive thymine or thymidine could not be demonstrated. Search for enzymes capable of transforming thymine via thymidine to thymidine-5′-monophosphate in crude extracts was performed, and the following enzymes were absent judging from enzyme assays: thymidine phosphorylase (EC 2.4.2.4), trans-
N
-deoxyribosylase (EC 2.4.2.6), and thymidine kinase (EC 2.7.1.21). The enzymes responsible for the phosphorylation of thymidine-5′-monophosphate to thymidine-5′-triphosphate were present in crude extracts. Radioactive uracil was readily incorporated into both ribonucleic acid and deoxyribonucleic acid, the ratio being 6:1, and radioactivity was found only in pyrimidine bases. No uptake of uridine could be demonstrated. Uridine-5′-monophosphate pyrophosphorylase (EC 2.4.2.9) activity was detected in crude extracts, suggesting that uracil is converted directly to uridine-5′-monophosphate which is then phosphorylated to uridine-5′-triphosphate or transformed to other ribo- and deoxypyrimidine nucleotides.
Translucent Colony Form of the Gram-Negative, Levan-Producing Bacterium,
Aerobacter levanicum
Authors: Takeshita Masaru
Published: January 2020

A spontaneously occurring variation of
Aerobacter levanicum
, affecting the appearance of colonies on sucrose agar (opaque to translucent colony form), has been observed and studied. This appears to be a mutation that is accompanied by a significant increase in levansucrase (EC 2.4.1.10) activity, in levan production, and by a change in some of the properties of levansucrase.
Ribonucleic Acid Polymerase in a Thermosensitive Sporulation Mutant (ts-4) of
Bacillus subtilis
Authors: Orrego C. , Kerjan P. , De Nadra M. C. Manca , Szulmajster J.
Published: January 2020

Partially synchronized cultures of a
Bacillus subtilis
thermosensitive sporulation mutant (ts-4) and the 168
try
−
try
−
(168tt) parental strain were infected with the virulent phage φe at various times during their growth cycle at 30 and 42 C (permissive and restrictive temperatures, respectively). It was shown that at the restrictive temperature the burst size in the parental strain was two- to threefold lower than in the ts-4 mutant. No such difference was observed at the permissive temperature. However, the time at which this difference was observed excludes a correlation between the burst size and initiation of the sporulation process. It was further found that the capacity to transcribe in vitro phage φe deoxyribonucleic acid by partially purified ribonucleic acid (RNA) polymerase from both strains decreased sharply if the source of enzyme was sporulating cells instead of vegetative ones. However, a similar decrease, although to a lesser extent, was observed with the RNA polymerase isolated from stationary-phase cells of the ts-4 mutant grown at the nonpermissive temperature, or with the enzyme derived from several other zero-stage sporulation mutants. At no time was a structural modification in the β subunits of the RNA polymerase observed during growth of the sporulating bacteria. We have also shown that, in addition to the relatively low specific activity of the RNA polymerase, the level of the intracellular protease activity is about 15-fold lower in the ts-4 mutant grown at the restrictive temperature than that of the parental strain grown at the same temperature. At the permissive temperature no such difference was observed between these two strains. However, the present data do not allow us to establish a correlation among the low content of intracellular protease, the weak specific activity of the RNA polymerase, and the loss of the sporulation capacity in the ts-4 mutant grown at the restrictive temperature.
Regulation of a Sulfur-Controlled Protease in
Neurospora crassa
Authors: Hanson Musetta A. , Marzluf George A.
Published: January 2020

Wild-type
Neurospora crassa
produces and secretes extracellular protease(s) when grown on a medium containing a protein as its principle sulfur source. Readily available sulfur sources, such as sulfate or methionine, repress the synthesis of the proteolytic activity. Preliminary characterization of the proteolytic enzyme shows it to have a molecular weight of about 31,000, a pH optimum of 6 to 9 with casein as substrate, and esterolytic activity against acetyl-tyrosine ethyl ester with a pH optimum of 8.5. The enzyme activity is completely inhibited by diisopropylfluorophosphate, partially inhibited by ethylenediaminetetraacetate, but unaffected by iodoacetate. The proteolytic activity is temperature labile and is reduced by 75% within 15 min at 60 C. Synthesis of the protease activity is induced by proteins, and to a lesser extent by large-molecular-weight polyamino acids, but not at all by small peptides or amino acid mixtures. During conidial out-growth, the protease(s) first appears at about 8 h and continues to increase while the cells are in an active growth phase. When a low concentration of sulfate is present, the protease(s) is not produced until about 18 h, suggesting that the sulfate must first be used by the cells before the protease is either synthesized or released.
Effect of the Prophage and Penicillinase Plasmid of the Recipient Strain Upon the Transduction and the Stability of Methicillin Resistance in
Staphylococcus aureus
Authors: Cohen Sidney , Sweeney Helen M.
Published: January 2020

Transduction of a methicillin-resistance determinant (
mec
) in
Staphylococcus aureus
RN450 was dependent on its prior lysogenization with an appropriate temperate phage. In addition, an appropriate transduced penicillinase plasmid was usually required. Some phage 80-resistant variants of RN450 or of its parental lysogenic strain, NCTC 8325, were also effective recipients for transduction of
mec
. Elimination of prophage from RN450 abrogated its effectiveness as a transductional recipient of
mec
. Elimination of prophage from a methicillin-resistant transductant of RN450 reduced resistance to undetectable levels in six of seven phage-eliminated strains. In four of these a variable number of clones again became phenotypically resistant after lysogenization alone or lysogenization combined with reintroduction of a penicillinase plasmid. In two prophage-eliminated strains, no evidence of residual
mec
could be adduced. The establishment, expression, or stability of the transduced
mec
in strain RN450 appeared to depend on some function determined by a prophage or a prophage and a penicillinase plasmid.
Physiological Studies on the Recovery of Salt Tolerance by
Staphylococcus aureus
After Sublethal Heating
Authors: Hurst A. , Hughes A. , Beare-Rogers Joyce L. , Collins-Thompson D. L.
Published: January 2020

Cultures of
S. aureus
in 100 mM potassium phosphate buffer heated at 52 C for 15 min lost their tolerance to 7.5% NaCl. After incubation in a complex growth medium or in a diluted dialyzed medium in which unheated cells were unable to grow, salt tolerance was regained. Heat injury caused 30% loss of lipid. During recovery, the concentration of C
15
and C
17
fatty acids returned to normal, and there appeared to be an oversynthesis of C
16
and C
18
unsaturated acids. Penicillin abolished the latter reaction without affecting recovery; chloramphenicol did not affect fatty acid oversynthesis but reduced recovery. The K/Na ratio was 12.6 in control cells and 3.4 in injured cells, where it remained during the recovery of salt tolerance. Aspartate uptake was about 10% of the control level after injury and about 35% at recovery. Control cells grew without a lag on subculture, but injured cells which had regained their salt tolerance needed about 2 more h of incubation. Cells recovering with penicillin needed 6 more h, and cells recovering with chloramphenicol did not grow without a prolonged lag. Cells of
S. aureus
, therefore, may recover their salt tolerance while various membrane functions are still damaged.
Glucolysis in
Pseudomonas putida
: Physiological Role of Alternative Routes from the Analysis of Defective Mutants
Authors: Vicente M. , Cánovas J. L.
Published: January 2020

A number of mutants in which glucolysis is impaired have been isolated from
Pseudomonas putida
. The study of their behavior shows that this organism possesses a single glucolytic pathway with physiological significance. The first step of the pathway consists in the oxidation of glucose into gluconate. Two proteins with glucose dehydrogenase activity appear to exist in
P. putida
but the reasons for this duplicity are not clear. The process continues with the formation of 2-ketogluconate which is in turn converted into gluconate-6-phosphate. This is proved by the fact that mutants unable to form gluconate-6-phosphate from 2-ketogluconate show extremely slow growth on glucose or gluconate (generation times are increased more than 100 times). Other possible routes for the conversion of glucose into gluconate-6-phosphate, the glucose-6-phosphate pathway, or the direct phosphorylation of the gluconate formed by glucose oxidation are only minor shunts in
P. putida
. The Entner-Doudoroff enzymes, which catalyze the conversion of gluconate-6-phosphate into pyruvate and triosephosphate, appear to be essential to grow on glucose and also on gluconate and 2-ketogluconate. A significative role of the pentose route in the catabolism of these substrates is not apparent from this study. In contrast,
P. putida
strains showing no activity of the Entner-Doudoroff enzymes grow readily on fructose, although there is evidence that this hexose is at least partially catabolized via gluconate-6-phosphate.
Sporulation Synchrony of
Saccharomyces cerevisiae
Grown in Various Carbon Sources
Authors: Fast Dale
Published: January 2020

Sporulation of several strains of
Saccharomyces cerevisiae
grown in a variety of carbon sources that do not repress the tricarboxylic acid cycle enzymes was more synchronous than the sporulation of cells grown in medium containing dextrose which does repress those enzymes. Dextrose-grown cells showed optimal sporulation synchrony when inoculated into sporulation medium from early stationary phase when the dextrose in the medium is exhausted. Logarithmic-phase cells grown in either non-fermentable carbon sources (acetate and glycerol) or a fermentable carbon source that does not repress tricarboxylic acid cycle enzymes (galactose) sporulated more synchronously than the early stationary-phase dextrose cells. Attempts were made to sporulate cells taken from both complex and semidefined media. The semidefined acetate medium failed to support the growth of a number of strains. However, cells grown in the complex acetate medium, as well as both complex and semidefined glycerol and galactose media, sporulated with better synchrony than did the dextrose-grown cells.
Role of Methionine in Biosynthesis of Prodigiosin bySerratia marcescens
Authors: Qadri S. M. Hussain , Williams Robert P.
Published: January 2020

Methionine alone did not allow biosynthesis of prodigiosin (2-methyl-3-amyl-6-methoxyprodigiosene) in nonproliferating cells (NPC) ofSerratia marcescensstrain Nima. However, when methionine was added to NPC synthesizing prodigiosin in the presence of other amino acids, the lag period for synthesis of prodigiosin was shortened, an increased amount of the pigment was formed, and the optimal concentrations of the other amino acids were reduced. Less prodigiosin was synthesized when addition of methionine was delayed beyond 4 h. The specific activity of prodigiosin synthesized by addition of14CH3-methionine was 40 to 50 times greater than that synthesized from methionine-2-14Cor14COOH-methionine. NPC of mutant OF ofS. marcescenssynthesized norprodigiosin (2-methyl-3-amyl-6-hydroxyprodigiosene), and the specific activity of this pigment synthesized in the presence of14CH3-methionine was only 5 to 13 times greater than that synthesized from methionine-2-14Cor14COOH-methionine. A particulate, cell-free extract of mutant WF ofS. marcescensmethylated norprodigiosin to form prodigiosin. When the extract was added to NPC of mutant OF synthesizing norprodigiosin in the presence of14CH3-methionine, the prodigiosin formed had 80% greater specific activity than the norprodigiosin synthesized in the absence of the extract. The C6 hydroxyl group of norprodigiosin was methylated in the presence of the extract and methionine. Biosynthesis of prodigiosin by NPC of strain Nima also was augmented by addition ofS-adenosylmethionine. Various analogues of methionine such as norleucine, norvaline, ethionine, and α-methylmethionine did not affect biosynthesis of prodigiosin by NPC either in the presence or absence of methionine.
Electron Microscopy of the Carboxysomes (Polyhedral Bodies) of
Thiobacillus neapolitanus
Authors: Shively J. M. , Ball Frances L. , Kline Betty W.
Published: January 2020

The carboxysomes of
Thiobacillus neapolitanus
are shown, by electron microscopy, to consist of a paracrystalline array of 10-nm particles surrounded by a “membrane.” The 10-nm particles have a center hole or depression and have been previously identified as ribulose diphosphate carboxylase. The membrane is a monolayer approximately 3.5-nm thick.
Stability of
Candida utilis
Cells and Spheroplasts Toward Gravitational Forces
Authors: Nakamura K. D. , Schlenk F.
Published: January 2020

Candida utilis
cells and spheroplasts containing uric acid crystals in their vacuoles were not damaged by the mechanical stress of centrifugation at 20,000 ×
g
for 10 min, as judged by plating, microscopy, and spectrophotometry.
Amino Acid Biosynthesis in the Spirochete
Leptospira
: Evidence for a Novel Pathway of Isoleucine Biosynthesis
Authors: Charon Nyles W. , Johnson Russell C. , Peterson David
Published: January 2020

Radioactive carbon dioxide was incubated with growing cells of
Leptospira interrogans
serotypes
semaranga
and
tarassovi
, and the specific activities and distribution of the label within the cellular amino acids were determined. The origins of the carbon skeletons of all the acid-stable amino acids except isoleucine were found to be consistent with known biosynthetic pathways for these amino acids. Experiments using radioactive carbon dioxide and other tracers indicated that most of the isoleucine was synthesized by a pathway not involving threonine. The origin of the carbon skeleton of isoleucine consisted of two residues of pyruvate (carbons 2 and 3) and acetate of acetyl-coenzyme A by this pathway. Isotope competition studies indicated that the pathway was regulated by isoleucine. The results are discussed in relation to two proposed pathways of isoleucine biosynthesis involving citramalate as an intermediate.
Genetic Analysis of the Leucine Region in
Escherichia coli
B/r: Gene-Enzyme Assignments
Authors: Yang Huey-Lang , Kessler Donald P.
Published: January 2020

Genetic mapping by transduction and conjugation using F
−
and F′ strains carrying either point mutations in the
l
-arabinose or leucine regions or
ara-leu
fusion-deletion mutations has resulted in a detailed genetic map of the arabinose-leucine region of
Escherichia coli
B/r. These studies have identified four genes in the leucine region having the same order as found in
Salmonella typhimurium: ara... leuDCBA
.
Conditional Mutator Gene in
Escherichia coli
: Isolation, Mapping, and Effector Studies
Authors: Degnen Gerald E. , Cox Edward C.
Published: January 2020

A mutator gene,
mutD5
, whose phenotype is conditional, has been identified in
Escherichia coli
. By P1 transduction it has been shown to lie at about 5.7 min on the chromosome, being co-transduced with
proA
and
argF
. In rich medium, streptomycin- and nalidixic acid-resistant mutation frequencies are 50 to 100 times higher than those in minimal medium. In minimal medium, the
mutD5
-induced mutation frequencies are still 50 to 100 times above co-isogenic wild-type (
mut
+
) levels. Similar results were obtained with all markers tested. Mutant frequencies can be raised by thymidine in the medium at concentrations as low as 0.04 μM, or by the endogenous generation of thymidine from thymine plus a deoxyribosyl donor. Deoxyadenosine, various ribonucleosides, thymine, and 2-deoxyribose do not stimulate mutation. None of these effects are related to growth rate, since growth rate and mutation rate can be decoupled completely.
Yeast Killer Mutants with Altered Double-Stranded Ribonucleic Acid
Authors: Vodkin Michael , Katterman Frank , Fink Gerald R.
Published: January 2020

Killer strains of
Saccharomyces cerevisiae
contain two species of double-stranded ribonucleic acid (
ds
RNA) with molecular weights estimated at 2.5 × 10
6
(
L
) and 1.4 × 10
6
(
M
). The
M
component appears to have a high adenine content. All mutants of killer which are defective for both the toxin and immunity functions lack the
M ds
RNA. One of these mutants has a novel
ds
RNA with a molecular weight of 5 × 10
5
. Another class of killer mutants contains strains which are defective for either the toxin or the immunity function. They include temperature-sensitive killers, superkillers, and immunity-minus strains. The
ds
RNA profile of temperature-sensitive killers resembles that of the standard killer. The superkiller has 2.5 times more of the
M ds
RNA (1.4 × 10
6
daltons) than does the standard killer. Immunity-minus killers have, in addition to the two
ds
RNAs species of standard killer, a novel
ds
RNA with a molecular weight of 2.5 × 10
5
. The data are consistent with the hypothesis that the
M
RNA controls toxin production. In addition, the two RNAs,
L
and
M
, seem to be regulated together. When the
M
RNA is missing, the amount of
L
is either greatly elevated or greatly reduced.
Phycobilisomes in Blue-Green Algae
Authors: Wildman Ruth B. , Bowen C. C.
Published: January 2020

Fifteen species of freshwater blue-green algae, including unicellular, filamentous, and colonial forms, were subjected to a variety of fixatives, fixation conditions, and stains for comparison of the preservation of phycobilisomes. Absorption spectra of the corresponding in vivo and released photosynthetic pigments, in 10 of the species that were maintained in culture, demonstrated the presence of phycocyanin in all 10 species and phycoerythrin in only 2 of them. Spectroscope and electron microscope evidence was obtained for localization of phycobiliproteins in phycobilisomes of
Nostoc muscorum
. Phycobilisomes were observed in all species examined in situ, strenghening the hypothesis that phycobilisomes are common to all phycobiliprotein-containing photosynthetic blue-green algae.
Role of Menaquinone in Nitrate Respiration in
Staphylococcus aureus
Authors: Sasarman A. , Purvis Peggy , Portelance V.
Published: January 2020

Two menaquinone-deficient and one aromatic-deficient mutants of
Staphylococcus aureus
were unable to reduce nitrate to nitrite. Reinitiation of menaquinone synthesis in the aromatic-deficient mutant by growing it with shikimic acid restored its nitrate respiratory activity. The results clearly demonstrate a role for menaquinone in nitrate respiration in
Staphylococcus aureus
.
Mutant ofAzotobacter vinelandiiThat Hyperproduces Nitrogenase Component II
Authors: Shah Vinod K. , Davis L. C. , Stieghorst M. , Brill Winston J.
Published: January 2020

A mutant strain ofAzotobacter vinelandiithat is unable to fix N2produces high levels of nitrogenase component II. Activities of revertants from this mutant strain indicate that a single genetic lesion is responsible for both hyperproduction of component II and the inability to produce component I.
Transport of Biosynthetic Intermediates: Homoserine and Threonine Uptake in
Escherichia coli
Authors: Templeton Bonnie A. , Savageau Michael A.
Published: January 2020

Although amino acid transport has been extensively studied in bacteria during the past decade, little is known concerning the transport of those amino acids that are biosynthetic intermediates or have multiple fates within the cell. We have studied homoserine and threonine as examples of this phenomenon. Homoserine is transported by a single system which it shares with alanine, cysteine, isoleucine, leucine, phenylalanine, threonine, tyrosine, and valine. The evidence for this being the sole system for homoserine transport is (i) a linear double-reciprocal plot showing a homoserine

K
m

of 9.6 × 10
−6
M, (ii) simultaneous reduction by 85% of homoserine and branched-chain amino acid uptake in a mutant selected for its inability to transport homoserine, and (iii) simultaneous reduction by 94% of the uptake of homoserine and the branched-chain amino acids by cells grown in millimolar leucine. Threonine, in addition to sharing the above system with homoserine, is transported by a second system shared with serine. The evidence for this second system consists of (i) incomplete inhibition of threonine uptake by any single amino acid, (ii) only 70% loss of threonine uptake in the mutant unable to transport homoserine, and (iii) only 40% reduction of threonine uptake when cells are grown in millimolar leucine. In this last case, the remaining threonine uptake can only be inhibited by serine and the inhibition is complete.