bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of Tryptophan Pyrrolase Activity in
Xanthomonas pruni
Authors: Wagner Conrad , Brown Albert T.
Published: January 2020

Tryptophan pyrrolase was studied in partially purified extracts of
Xanthomonas pruni
. The dialyzed enzyme required both heme and ascorbate for maximal activity. Other reducing agents were able to substitute for ascorbate. Protoporphyrin competed with heme for the enzyme, suggesting that the native enzyme is a hemoprotein. The enzyme exhibited sigmoid saturation kinetics. Reduced nicotinamide adenine dinucleotide (NADH), reduced nicotinamide adenine dinucleotide phosphate (NADPH), nicotinic acid mononucleotide, and anthranilic acid enhanced the sigmoid kinetics and presumably bound to allosteric sites on the enzyme. The sigmoid kinetics were diminished in the presence of α-methyltryptophan. NAD, NADP, nicotinic acid, nicotinamide, nicotinamide mononucleotide, and several other related compounds were without effect on the activity of the enzyme. These data indicate that the activity of the enzyme is under feedback regulation by the ultimate end products of the pathway leading to NAD biosynthesis, as well as by certain intermediates of this pathway.
Deoxyribonucleic Acid Base Composition of
Rothia dentocariosa
as Determined by Thermal Denaturation
Authors: Hammond B. F.
Published: January 2020

The moles per cent guanine plus cytosine (GC) of 10 filamentous strains of
Rothia dentocariosa
ranged from 65.4 to 69.7. Major differences were not observed in the base composition of a filamentous form (69.7 moles% GC) and its coccal variant (68.0 moles% GC).
Iron Transport in
Salmonella typhimurium:
Mutants Blocked in the Biosynthesis of Enterobactin
Authors: Pollack J. R. , Ames Bruce N. , Neilands J. B.
Published: January 2020

A number of mutants of
Salmonella typhimurium
were isolated which are blocked in the biosynthesis of enterobactin, an iron chelator that is secreted by the wild-type bacteria when they are grown on low iron media. One class of these
enb
mutants accumulates the enterobactin precursor 2,3-dihydroxybenzoic acid, and another class does not accumulate any detectable catechol precursor. The
enb
mutants grow very well on a glucose-mineral salts medium. Addition of citrate, itself an iron chelator, to the medium drastically inhibits growth unless the medium is supplemented with enterobactin or iron salts. Citrate inhibits iron uptake from the medium by
enb
mutants; enterobactin counteracts this inhibition and also, by itself, increases iron uptake. Thus, the apparent function of enterobactin is to promote the absorption of iron from the medium by the bacteria. Transduction experiments showed that the genes for enterobactin biosynthesis are closely linked on the
S. typhimurium
chromosome. It is suggested that they form an operon which is repressed by the presence of iron.
S. typhimurium
can utilize the iron chelate ferrichrome. (Deferriferrichrome is a cyclic hexapeptide that is produced by some fungi but not by
S. typhimurium
.) The
enb
mutants use ferrichrome as an effective growth factor.
Calorific Content of Certain Bacteria and Fungi
Authors: Prochazka G. J. , Payne W. J. , Mayberry W. R.
Published: January 2020

Calorific contents of dried cells of several representative species of bacteria (gram-negative rods and gram-positive rods and cocci), two species of yeasts, and a filamentous fungus were determined by bomb calorimetry. The grand mean was 5,383 cal per g of ash-free dry weight. This value was then used to determine quantity of energy assimilated (
E
a
) during growth. Subsequently,
E
a
was employed in the equation:
Y
kcal
= Y/(
E
a
+
E
d
), where
Y
kcal
is the yield of cells per kilocalorie of energy taken from a culture medium,
Y
is the yield per mole of substrate utilized,
E
a
is
Y
times caloric content of the cells, and
E
d
is the energy expended by oxidative dissimilation. An estimate of
E
d
was obtained for a number of experiments by multiplying the moles of oxygen consumed per mole of substrate utilized during growth by the average quantity of energy utilized to reduce a mole of oxygen with electrons from organic compounds (106 kcal). From previous studies in our laboratories, a value for
Y
kcal
of 0.118 g/kcal was predicted. The mean value for data from five studies of aerobic growth of prototrophic heterotrophs was found to be 0.111.
Effect of Type of Carbohydrate on Amino Acid Accumulation and Utilization by
Tetrahymena
Authors: Reynolds Howard
Published: January 2020

Both concentration and pattern of free amino acids in
Tetrahymena pyriformis
, as well as utilization, synthesis, and excretion of amino acids, were affected by type of carbohydrate in growth media. With glucose, cell pool concentrations were higher than with dextrin, and alanine and glycine together accounted for an average of 45% of the total pool. These two amino acids accumulated in similar proportions when their synthesis from essential amino acids was a prerequisite, as when they were provided by growth media, but they constituted only 15 to 18% of the free amino acids in cells from media with dextrin. Alanine, glycine, and glutamic acid were excreted into the medium regardless of whether they were provided by starting media; hence, they appear to be end products of the required metabolism of some of the essential amino acids. Both accumulation and excretion of the above non-essential amino acids were nearly twice as extensive in media providing glucose as the only carbohydrate as when the carbohydrate supplied was dextrin or dextrin plus glucose. Thus, the observed differences are not attributable to differences in osmolarity of monosaccharide and polysaccharide media. Free amino acid differences do not appear to be the immediate cause of the different growth-stimulating properties of such carbohydrates.
Release of Alkaline Phosphatase from Cells of
Pseudomonas aeruginosa
by Manipulation of Cation Concentration and of
p
H
Authors: Cheng K.-J. , Ingram J. M. , Costerton J. W.
Published: January 2020

Pseudomonas aeruginosa
ATCC 9027 contains an inducible alkaline phosphatase. The enzyme is readily removed from 14-hr cells by washes in 0.2
m
MgCl
2
,
p
H 8.4. Similar washes in tris(hydroxymethyl)aminomethane buffer, 20% sucrose, monovalent ions, or water partially release enzyme from the cells. The release of alkaline phosphatase is correlated with an increased release of protein and retention of internal enzymes. The effect of 0.2
m
MgCl
2
washing upon the cells is minimal since both viability and growth rates remain unchanged as compared to water washing. Although cells are plasmolyzed in both 0.2
m
MgCl
2
and 20% sucrose, it is evident that plasmolysis alone is unable to account for total enzyme release and that a divalent metal, i.e. Mg
2+
, augments the release pattern. Growing cells in the presence of increasing concentrations of MgCl
2
or at increased
p
H values results in an almost total secretion of the enzyme to the culture filtrate. The findings suggest that
P. aeruginosa
alkaline phosphatase is linked to the exocytoplasmic region through divalent metal ion, presumably Mg
2+
, bridges.
Response of an
Escherichia coli
-Bound Fluorescent Probe to Colicin E1
Authors: Cramer W. A. , Phillips S. K.
Published: January 2020

The fluorescent probe, 8-anilino-1-napthalenesulfonate (ANS) binds to
Escherichia coli
, showing an enhanced fluorescence. The interaction of colicin E1 with sensitive cells causes an increase of about 100% in the fluorescence of the bound ANS, and this change at equilibrium has an apparent “all-or-none” nature as a function of E1 multiplicity. Approximately 6 to 8% of the ANS is bound to the cells at equilibrium. The colicin E1-induced fluorescence increase can be attributed partly to an increase in ANS binding and partly to an increase in the fluorescence yield of the bound ANS. The kinetics of the E1-induced fluorescence increase in sensitive cells are very similar to those of the adenosine triphosphate decrease. The phosphorylation uncoupler
p
-trifluoromethoxy-carbonylcyanidephenylhydrazone also causes a large change in the fluorescence of bound ANS. Colicin E2 or E3 does not cause any fluorescence change, nor does colicin E1 cause fluorescence change with a colicinogenic strain. ANS appears to be a probe of structural or conformational change in the cell envelope that is closely associated with the colicin E1-induced adenosine triphosphate decrease.
Mechanism of Chloramphenicol Resistance in
Staphylococcus epidermidis
Authors: Shaw W. V. , Bentley D. W. , Sands L.
Published: January 2020

The mechanism of chloramphenicol resistance in several multiple-resistant
Staphylococcus epidermidis
strains has been studied and shown to be due to the presence of the enzyme, chloramphenicol acetyltransferase. As with
S. aureus
, the inactivating enzyme in
S. epidermidis
appears to be the product of a structural gene on the chloramphenicol plasmid because resistance and enzyme activity are concurcurrently lost after growth in acridine orange or at elevated temperatures. The synthesis of chloramphenicol acetyltransferase in
S. epidermidis
has been compared with the function of a similar enzyme in chloramphenicol-resistant
S. aureus
with the conclusion that the kinetics of induction, products of the reaction, and general properties of the enzymes are identical. The chloramphenicol acetylating enzyme from
S. epidermidis
has been purified to a state of homogeneity and compared with the analogous purified
S. aureus
enzyme. Both purified preparations consist of native enzymes with molecular weights of 80,000, and evidence is presented that is consistent with their being made up of four identical subunits of 20,000 each. The two staphylococcal enzymes are identical with respect to
p
H optimum, apparent affinity (
K
m
) for chloramphenicol, heat denaturation, and immunological reactivity, but they differ in electrophoretic mobility, chromatographic behavior, substrate specificity, and sensitivity to inhibition by mercuric ion.
Fusions of the
lac
and
trp
Regions of the
Escherichia coli
Chromosome
Authors: Miller Jeffrey H. , Reznikoff William S. , Silverstone Allan E. , Ippen Karin , Signer Ethan R. , Beckwith Jonathan R.
Published: January 2020

Two classes of strains were studied in which the
lac
operon is transposed to a chromosomal site close to the
tonB
and
trp
loci. The two classes differ in the orientation of the
lac
region on the chromosome. In both types of strains,
tonB
mutants were selected in which deletions removing the
tonB
locus also caused a fusion of the
lac
and
trp
regions. The study of the properties of such fusion strains provides information on the control of both the
lac
and
trp
operons.
Periodic Density Fluctuation During the Yeast Cell Cycle and the Selection of Synchronous Cultures
Authors: Hartwell Leland H.
Published: January 2020

Yeast cells undergo periodic fluctuations in density during the cell division cycle such that a minimum in density occurs at the time of cell separation whereas a maximum occurs between the time of deoxyribonucleic acid replication and nuclear division. Synchronous cultures can be selected from asynchronously growing cell cultures by withdrawing the cells of least or greatest density after banding in Renografin-sucrose density gradients. This technique is rapid, reproducible, and almost unlimited in capacity.
Penicillin-Lysozyme Conversion of
Clostridium botulinum
Types A and E into Protoplasts and Their Stabilization as L-Form Cultures
Authors: Brown George W. , King Gretchen , Sugiyama H.
Published: January 2020

When logarithmically growing cultures of
Clostridium botulinum
types A and E are treated with penicillin in a liquid medium containing 8% polyethylene glycol, protoplast-like spherical bodies are formed. The penicillin effect shows a dose-response relationship; the largest yield of converted forms is obtained with 10,000 units/ml, but the treatment leaves many intact bacilli. Lower antibiotic concentrations produce smaller numbers of spherical bodies, but lysis of bacilli results in suspensions that are relatively free of rods. Cells grown under the same conditions and treated with 250 μg of lysozyme/ml do not form spherical bodies. However, a combination of 1,250 to 2,500 units of penicillin and 100 μg of lysozyme/ml yields suspensions which have sphere counts in excess of 1.0 × 10
8
/ml and only a few intact rods. The state of the culture at the time of addition of the antibiotic and enzyme is critical. Suspensions of these protoplasts can be adapted to grow as stable L-form cultures producing the same toxin type as the parent cultures.
Staphylococcus aureus
Protoplasting Induced by
d
-Cycloserine
Authors: Virgilio R. , Gonzalez C. , Muñoz Nubia , Cabezon Teresa , Mendoza Silvia
Published: January 2020

Addition of sublethal doses of
d
-cycloserine to growing cells of
Staphylococcus aureus
induces the rupture of the cell wall along an equatorial ring, thus allowing the liberation of protoplasts.
Gene Dosage for 5
S
Ribosomal Ribonucleic Acid in
Escherichia coli
and
Bacillus megaterium
Authors: Pace B. , Pace N. R.
Published: January 2020

The number of gene copies for 5
S
ribosomal ribonucleic acid (rRNA), relative to that for 16 and 23
S
rRNA, has been determined by deoxyribonucleic acid (DNA)-RNA hybridization for
Escherichia coli
and
Bacillus megaterium
. In both cases, the number of 5
S
rRNA genes equals the number of 16 or 23
S
rRNA genes. Rapid procedures for preparing extremely highly purified DNA suitable for DNA-RNA hybridization experiments and chemically pure 5
S
rRNA are described.
Methylation of the Flagellin of
Salmonella typhimurium
Authors: Tronick Steven R. , Martinez Rafael J.
Published: January 2020

The methylation of endogenous proteins by
Salmonella typhimurium
SL 870 was investigated in cell-free extracts by using
S
-adenosylmethionine as methyl donor. Several lines of evidence are presented which suggest that one of the methylated products is the protein flagellin. Mutant strains of SL 870 (
nml
−
fla
+
and
nml
+
fla
−
) were also found to synthesize epsilon-
N
-methyl-lysine. It is proposed that
S. typhimurium
possesses at least two genes specifying different methylating enzymes. One gene product is a flagellin-specific methylating enzyme, whereas the other gene(s) codes for enzymes that methylate one or more other cell proteins.
Utilization of Glucose by
Clostridium thermocellum:
Presence of Glucokinase and Other Glycolytic Enzymes in Cell Extracts
Authors: Patni N. J. , Alexander James K.
Published: January 2020

Clostridium thermocellum
was shown to ferment glucose in a medium containing salts and 0.5% yeast extract. An active glucokinase was obtained with improved conditions for growth, assay, and preparation of cell extracts. Cell extracts appear to contain a glucokinase inhibitor that interferes with the assays at high protein concentrations. Glucokinase activity is stimulated about 60% by pretreatment with dithiothreitol. Little or no fructokinase or mannokinase activity was detected in cell extracts. The absence of glucokinase in mannitol-grown cells, the increase in glucokinase activity upon incubation of cell suspensions with glucose, and the lack of increase in activity when chloramphenical is added are evidence that glucokinase is an inducible enzyme. The following enzymes were detected in cell extracts (the enzyme activities are shown in parentheses are micromoles per minute per milligram or protein at 27 C): glucokinase (0.48), phosphoglucose isomerase (0.73), fructose 6-phosphate kinase (0.24), fructose diphosphate aldolase (0.59), glyceraldehyde 3-phosphate dehydrogenase (0.53), triose phosphate isomerase (0.13), phosphoglycerate kinase (0.20), phosphoglycerate mutase (0.20), enolase (0.28), pyruvic kinase (0.13), and lactic dehydrogenase (0.13). Glucose 6-phosphate dehydrogenase activity was absent or very low (0.0002) and 6-phosphogluconate dehydrogenase activity also was relatively low (0.015). From these data, it is proposed that carbohydrate metabolism in
C. thermocellum
proceeds by the Embden-Meyerhof pathway.
Purification of Intact Flagella from
Escherichia coli
and
Bacillus subtilis
Authors: DePamphilis M. L. , Adler Julius
Published: January 2020

A procedure is described for the purification of bacterial flagella in the form of a filament-hook-basal body complex (intact flagella) free from detectable cell wall, membrane, or cytoplasmic material. Spheroplasts produced with lysozyme and ethylenediaminetetraacetic acid were lysed with Triton X-100, and the flagella were purified by (NH
4
)
2
SO
4
precipitation, differential centrifugation, and CsCl gradient centrifugation. As much as 40% of the flagella were recovered, and they contained about one basal body per 4 to 6 μm of flagella. The same procedure developed for
Escherichia coli
was also successful for purifying intact flagella from
Bacillus subtilis
.
Ultrastructural Explanation for Snapping Postfission Movements in
Arthrobacter crystallopoietes
Authors: Krulwich Terry A. , Pate Jack L.
Published: January 2020

The ultrastructure of dividing rod-stage cells of
Arthrobacter crystallopoietes
was examined by electron microscopy. The cell walls consist of two layers. During cell division, the inner layer invaginates to form the septum. The outer layer does not participate in septum formation. After septum formation is completed, the two daughter cells remain attached by the outer layer of the cell wall. It appears that localized rupture of the outer layer during further wall growth is responsible for the phenomenon known as “snapping division” or “snapping postfission movement.”
Isolation and Characterization of a Glucosamine-Requiring Mutant of
Escherichia coli
K-12 Defective in Glucosamine-6-Phosphate Synthetase
Authors: Wu H. C. , Wu T. C.
Published: January 2020

A mutant was isolated from
Escherichia coli
K-12 which requires glucosamine or
N
-acetylglucosamine for growth. Depriving the mutant of glucosamine resulted in a rapid loss of viability of the cells, followed by a decrease in the turbidity of the culture. When the mutant cells were resuspended in broth media containing 10% sucrose, the rod-shaped cells became spheroplasts. However, the presence of sucrose in the media did not prevent the cells from losing their viability. This mutant was shown to be deficient in the activity of
l
-glutamine:
d
-fructose-6-phosphate aminotransferase (EC 2.6.1.16). The activity of the deaminating enzyme, 2-amino-2-deoxy-
d
-glucose-6-phosphate ketol-isomerase (EC 5.3.1.10), appeared to be normal in this mutant. The position of the mutation has been determined to be at the 74th min of the Taylor and Trotter map, as shown by cotransduction with
phoS
(90%) and
ilv
(25%) by using bacteriophage P1.
Deoxycytidine Triphosphate Deaminase: Identification and Function in
Salmonella typhimurium
Authors: Neuhard J. , Thomassen E.
Published: January 2020

The biosynthesis of 2′-deoxyuridine monophosphate (dUMP) has been studied in a cytidine- and uracil-requiring mutant of
Salmonella typhimurium
(DP-55). The dUMP pool and the thymidine monophosphate (dTMP) pool of DP-55, grown in the presence of
3
H-uracil and unlabeled cytidine, are found to have the same specific activities. However, only 30% of the dUMP and the dTMP is synthesized from a uridine nucleotide. Seventy per cent is derived directly from a cytosine compound. The identification and partial purification of a Mg
2+
-dependent 2′-deoxycytidine triphosphate (dCTP) deaminase from
S. typhimurium
suggests that the combined action of dCTP deaminase and 2′-deoxyuridine triphosphate pyrophosphatase accounts for 70% of the dUMP, and therefore the dTMP, synthesized in vivo. The introduction of a thymine requirement (i.e., a block in thymidylate synthetase) into DP-55 results in a 100-fold increase in the size of the dUMP pool. However, the relative contribution of the uridine and cytidine pathways to dUMP synthesis is unaltered. The high dUMP pool is accompanied by extensive catabolism of dUMP to uracil. Partial thymine starvation of the cells results in a significant increase in the dUMP and dCTP pools. Moreover, an increase in the contribution of the dCTP pathway to dUMP synthesis is observed. As a result of these changes the catabolism of dUMP to uracil is augmented.
Effects of Molybdate and Selenite on Formate and Nitrate Metabolism in
Escherichia coli
Authors: Lester Robert L. , DeMoss J. A.
Published: January 2020

The effects of adding molybdate and selenite to a glucose-minimal salts medium on the formation of enzymes involved in the anaerobic metabolism of formate and nitrate in
Escherichia coli
have been studied. When cells were grown anaerobically in the presence of nitrate, molybdate stimulated the formation of nitrate reductase and a
b
-type cytochrome, resulting in cells that had the capacity for active nitrate reduction in the absence of formate dehydrogenase. Under the same conditions, selenite in addition to molybdate was required for forming the enzyme system which permits formate to serve as an effective electron donor for nitrate reduction. When cells were grown anaerobically on a glucose-minimal salts medium without nitrate, active hydrogen production from formate as well as formate dehydrogenase activity depended on the presence of both selenite and molybdate. The effects of these metals on the formation of formate dehydrogenase was blocked by chloramphenicol, suggesting that protein synthesis is required for the increases observed. It is proposed that the same formate dehydrogenase is involved in nitrate reduction, hydrogen production, and in aerobic formate oxidation.
Biosynthetic Dihydroorotate Dehydrogenase from
Lactobacillus bulgaricus
Authors: Taylor Mary L. , Taylor W. Herman , Eames Donald F. , Taylor Craig D.
Published: January 2020

This paper describes the first detailed study on a dihydroorotate dehydrogenase involved in pyrimidine biosynthesis. In most organisms the enzyme is membrane-bound; however, a soluble dihydroorotate dehydrogenase was produced in relatively high levels when the anaerobe,
Lactobacillus bulgaricus
, was released from repression. The enzyme was purified 213-fold over derepressed levels with a 39% recovery of enzyme units. The enzyme showed only one minor protein contaminant when analyzed by polyacrylamide electrophoresis. It was characterized as a flavoprotein containing only flavine mononucleotide as the prosthetic group. Molecular weight estimations by gel filtration gave a value of approximately 55,000, which is one-half that of the degradative enzyme described by others. During aerobic oxidation of dihydroorotate, the rates of oxygen consumption, orotate formation, and hydrogen peroxide formation were equal, as would be expected in a flavoprotein-catalyzed reaction. The enzymatic activity with ferricyanide as acceptor was optimum around
p
H 7.7. The stimulation of enzymatic activity over a wide
p
H range by ammonium sulfate was attributed to an effect on the maximum velocity of the reaction. As analyzed by polyacrylamide electrophoresis, inactivation of the enzyme by visible light resulted in the appearance of a second protein band with lowered specific activity. The purified enzyme used redox dyes, oxygen, or cytochrome
c
as electron acceptors but was not active with pyridine nucleotides. Flavine adenine dinucleotide has been implicated at the active site for pyridine nucleotide reduction in the degradative enzyme. The biosynthetic enzyme lacks this flavine and the associated activity.
Biochemical Studies of Melibiose Metabolism in Wild Type and
mel
Mutant Strains of
Salmonella typhimurium
Authors: Levinthal Mark
Published: January 2020

I identified two enzyme activities, α-galactosidase and a galactoside permease, required for melibiose metabolism by
Salmonella typhimurium
. These activities are very low under normal growth conditions, but their production can be induced by melibiose and gratuitously by melibiitol. Melibiose induction is severely inhibited by glucose, but the glucose effect can be countered by 3′, 5′ cyclic adenosine monophosphate. I isolated two phenotypic classes of mutants not able to utilize melibiose as a carbon source. One class, Car
−
, is deficient in the phosphotransferase system. The other, Mel, lacks either α-galactosidase, galactoside permease, or both functions.
Balanced Macromolecular Biosynthesis in “Protoplasts” of
Streptococcus faecalis
Authors: Roth George S. , Shockman Gerald D. , Daneo-Moore Lolita
Published: January 2020

Osmotically fragile forms of
Streptococcus faecalis
9790 were grown in 0.5
m
sucrose- or 0.5
m
NH
4
Cl-stabilized medium. The “protoplast” cultures exhibit an average growth rate constant of 0.66 to 0.94 mass doublings/hr. In a variety of experiments, turbidity and the net content of protein, ribonucleic acid (RNA) and deoxyribonucleic acid increase at the same rate, indicating balanced macromolecular biosynthesis. A total of two to three mass doublings was obtained, with no evidence of cell division. After osmotic shock, “protoplast” cultures released 93 to 94% of their RNA content in a form not sedimentable at 12,800 ×
g
for 15 min, in contrast to streptococci, which released 7% of their RNA content after the same treatment.
Mannitol Uptake by
Saccharomyces cerevisiae
Authors: Maxwell W. A. , Spoerl Edward
Published: January 2020

The uptake of mannitol, a nonmetabolized hexitol, by
Saccharomyces cerevisiae
was measured. Various characteristics examined include: effects of temperature on uptake, inhibition of uptake by uranyl nitrate, competition for uptake by glucose, counterflow of mannitol by glucose, and the affinity of mannitol for a carrier system as measured by a Michaelis constant. That energy is required for uptake was shown by a decreased uptake in the presence of energy inhibitors, by an increased uptake upon addition of energy sources, and by the absence of uptake under anaerobic conditions with no fermentable energy sources available. That mannitol is bound to some cellular constituent after it enters the cell was shown by its attachment to non-dialyzable cell fragments and by the lack of an osmotic response, both of which are consistent with a minimal efflux.
Nitrogenase Activity in Cell-Free Extracts of the Blue-Green Alga,
Anabaena cylindrica
Authors: Smith R. V. , Evans M. C. W.
Published: January 2020

Cell-free extracts with high nitrogenase activity were prepared by sonic oscillation and French press treatment from the blue-gree alga
Anabaena cylindrica
. Extracts were prepared from cells grown on a 95% N
2
–5% CO
2
gas mixture followed by a period of nitrogen starvation under an atmosphere of 95% argon–5% CO
2
. No increase in the specific activity of extracts was achieved by breaking heterocysts. Activity (assayed by acetylene reduction) was found to be dependent on adenosine triphosphate (ATP), an ATP-generating system, and a low-potential reductant. Na
2
S
2
O
2
employed as reductant supports higher rates of nitrogenase activity than reduced ferredoxin. The activity is associated with a small-particle fraction that can be sedimented by ultracentrifugation. In contrast to the particulate nitrogenase of
Azotobacter
, which is stable in air, the
A. cylindrica
nitrogenase is an oxygen sensitive as nitrogenase prepared from anaerobic bacteria.
Ultracentrifugal Analysis of Staphylococcal Alpha Toxin
Authors: Forlani L. , Bernheimer A. W. , Chiancone E.
Published: January 2020

Ultracentrifugal examination of staphylococcal alpha toxin at different stages of purification showed the presence of a major component having a sedimentation coefficient of 2.8
S
, present to the extent of more than 90% of the sample, and identifiable with active toxin. Several minor components having
S
20,w
values of 11.5
S
, 8.5
S
, and 2.0
S
were detected. The 11.5
S
component presumably is identical with a toxin aggregate studied earlier and designated 12
S
; the 8.5
S
component appears to be delta toxin. A sedimentation equilibrium study of more highly purified material gave 32,700 as the best estimate of molecular weight of alpha toxin. Lowering the
p
H of the partially purified alpha toxin from 10.2 to 5.3 resulted in a small increase in
S
20,w
of the 11.5
S
component and in the disappearance of the 8.5
S
component, whereas the
S
20,w
, molecular weight, and hemolytic activity of the toxin remained constant. Exposure of toxin to
p
H 3.5 irreversibly reduced the
S
20,w
to 2.0
S
, the molecular weight to about 16,000, and caused irreversible inactivation. Raising the
p
H of acid-inactivated toxin and adding sodium dodecyl sulfate to 1% increased the
S
20,w
to near its normal value (2.7
S
) but did not restore activity.
Osmotic Regulation of Invertase Formation and Secretion by Protoplasts of
Saccharomyces
Authors: Kuo S.-C. , Lampen J. O.
Published: January 2020

Osmotic regulation of invertase formation and secretion by protoplasts of
Saccharomyces
was examined using sorbitol, KCl, NaCl, or magnesium sulfate as the osmotic support. The synthesis and secretion of the enzyme is remarkably sensitive to the osmolarity of the supporting medium irrespective of the particular support employed. Invertase formation was inhibited at high osmolarity and was maximal at 0.65 to 0.75 osmolal, even though some leakage of the intracellular enzyme α-glucosidase and of ultraviolet (UV)-absorbing materials occurred under these conditions. The reduction of invertase formation and secretion due to high osmolarity was eliminated promptly when protoplasts were transferred into a medium of lower osmolarity. The rate of fructose uptake and of threonine incorporation into protein was decreased by high osmolarity; also reduction of invertase formation could be partially reversed by increasing the level of sugar supplied as energy source. Thus changes in the permeability of the plasma membrane (and presumably also in its structure) are important factors in the response of protoplasts to high osmolarity, though certainly not the complete explanation. Protoplasts suspended in 0.8
m
sorbitol, with 10m
m
fructose as the energy source, increased their invertase level 5- to 10-fold during a 2-hr incubation without substantial release of α-glucosidase or UV-absorbing materials. Both the large and small forms of invertase were present in the protoplasts, but only the large form was released into the medium when enzyme was being actively synthesized. Formation and secretion of newly formed invertase and the release of enzyme initially present were inhibited by cycloheximide.
Two Mutations in the First Gene of the Histidine Operon of
Salmonella typhimurium
Affecting Control
Authors: Rothman-Denes Lucia , Martin Robert G.
Published: January 2020

Two strains with mutations in the first structural gene of the histidine operon of
Salmonella typhimurium
were characterized. (The first structural gene specifies the first enzyme of histidine biosynthesis, phosphoribosyltransferase, which is sensitive to feedback inhibition by histidine.) One mutation,
hisG3934
, results in a phosphoribosyltransferase which is no longer sensitive to feedback inhibition by histidine but is instead subject to inhibition by aspartic acid. The other mutation,
hisG3935
, allows the histidine operon to be partially repressed by several amino acids, including aspartic acid. Analysis of
hisG3935
is consistent with the hypothesis that phosphoribosyltransferase is directly involved in the regulation of the histidine operon.
Aspects of the Mechanism of Action of Some Cephalosporins
Authors: Russell A. D. , Fountain R. H.
Published: January 2020

Cephaloridine and cephalexin had no effect on ribonucleic acid (RNA), deoxyribonucleic acid (DNA), or protein synthesis in
Escherichia coli
. However, cephalosporin 7/30 [7-(
S
-benzylthioacetamido)-cephem-3-ylmethyl-
N
-dimethyldithiocarbamate-4-carboxylic acid] and dimethyldithiocarbamate (DMDT), which occupies the side chain at position 3 in the 7/30 molecule, inhibited protein synthesis (and, to a lesser extent, RNA and DNA syntheses) in
E. coli
and had an inhibitory effect on the growth of
Saccharomyces carlsbergensis
. A bioautograph technique showed that two inhibitory spots were obtained with 7/30 but only one such spot with cephaloridine. Release of DMDT onto or in the bacterial cell may be responsible for “unusual” mode of action of cephalosporin 7/30.
Physiological Studies of Biosynthetic Indole Excretion in
Bacillus alvei
Authors: Roth C. W. , Hoch J. A. , DeMoss R. D.
Published: January 2020

Bacillus alvei
excretes indole during early exponential growth in acid-hydrolyzed casein medium.
l
-Threonine is the amino acid responsible for “early” indole excretion, and the amount of indole excreted is directly related to the amount of
l
-threonine in the medium. “Early-indole” excretion can be prevented by the continuous addition of serine (3.1 μmoles per ml per hr) or by substituting a mutant with an impaired ability to degrade serine. The addition of serine to a culture during the period of indole excretion halts the excretion and stimulates indole utilization. Threonine is a competitive inhibitor of serine (
K
i
= 0.6
m
) in the tryptophan synthetase B reaction. The internal tryptophan concentration increases during the period of indole excretion, suggesting that threonine acts by increasing the activity of the tryptophan pathway. This view is supported by experiments demonstrating that anthranilic acid and indoleacrylic acid also stimulate indole excretion. A metabolic explanation is offered and discussed.
Mutation Preventing Capsular Polysaccharide Synthesis in
Escherichia coli
K-12 and Its Effect on Bacteriophage Resistance
Authors: Radke Kathryn L. , Siegel Eli C.
Published: January 2020

A mutant strain of
Escherichia coli
K-12 was found in which spontaneous mutation to phage T7 resistance occurred at a very low frequency. T7 resistance in the parental strain from which this mutant was derived resulted from a mutation to excess capsular polysaccharide synthesis. The mutation preventing T7 resistance,
non-9
, inhibited capsule formation when transduced into capsulated strains. The
non-9
mutation was cotransducible with
his
, the gene order in this region being
non-9 his Su-1
.
Non-Mendelian Mutation Allowing Ureidosuccinic Acid Uptake in Yeast
Authors: Lacroute Francois
Published: January 2020

Mutants of
Saccharomyces cerevisiae
capable of growth on a minimal medium supplemented with ureidosuccinic and glutamic acids have been isolated from a pyrimidineless strain. One of these mutants consistently yielded a non-Mendelian meiotic segregation. Moreover, the mitotic transmission of the mutation was very high. It is suggested that the mutation is nonchromosomal and could be mitochondrial. However, this mutation behaves very differently from other mitochondrial mutations.
Agrobacterium tumefaciens
Ribonucleic Acid Synthesis in Tomato Cells and Crown Gall Induction
Authors: Stroun M. , Anker P. , Gahan P. , Rossier A. , Greppin H.
Published: January 2020

Purified
Agrobacterium tumefaciens
deoxyribonucleic acid (DNA) does not produce crown gall tumors in growing plants, conditioned by wounding, as the living bacteria do. Purified bacterial DNA migrates in the plant and replicates, but it is not transcribed in our experimental conditions. On the contrary, when DNA is released naturally from bacteria into plant cells, a bacterial ribonucleic acid (RNA) can be found in these cells. There seems to be a direct relation between the appearance of
A. tumefaciens
RNA in the plant cells and the induction of the tumor.
Linkage Groups in
Bacillus pumilus
Determined by Bacteriophage PBS1-Mediated Transduction
Authors: Lovett Paul S. , Young Frank E.
Published: January 2020

Two linkage groups were established in
Bacillus pumilus
NRRL B-3275 by bacteriophage PBS1 transduction. Group L contains the auxotrophic markers
gly, his
, and
met
. Group M contains the markers
argO, met, ura
, and
cys
.
Regulation of Extracellular Protease Production in
Bacillus cereus
T: Characterization of Mutants Producing Altered Amounts of Protease
Authors: Aronson A. I. , Angelo N. , Holt S. C.
Published: January 2020

Twenty-nine mutants of
Bacillus cereus
T were selected on casein agar for their inability to produce large amounts of extracellular protease. They all formed spores, and 27 were also auxotrophs for purines or pyrimidines. Upon reversion to prototrophy, a large fraction regained the capacity to produce protease. Conversely, reversion to normal protease production resulted in loss of the purine or pyrimidine requirement in a large fraction of the revertants. One spontaneous low-protease-producing pyrimidine auxotroph studied in detail grew as well as the wild type and produced spores which were identical to those produced by the wild type on the basis of heat resistance, dipicolinic acid content, density, and appearance in the electron microscope. The rate of protein turnover in the mutant was the same as the wild type. The mutant did grow poorly, however, when casein was the principal carbon source. A mutant excreting 5 to 10 times as much protease as the wild type was isolated as a secondary mutation from the hypoproducer discussed above. Loss of the pyrimidine requirement in this case did not alter the regulation of protease production. Although the secondary mutant grew somewhat faster in most media than the wild type, the final cell yield was lower. The spores of this mutant appeared to have excess coat on the basis of both electron microscopic and chemical studies. There appear to be closely related but distinct catabolic controls for both extracellular protease and spore formation. These controls can be dissociated as for the hypoproducers but can also appear integrated as for the hyperprotease producer.
Variability of Photodynamic Killing in
Escherichia coli
and Avoidance of Variability with Agar
Authors: O'Bryan Corliss , Harrison Arthur P.
Published: January 2020

Photodynamic killing of
Escherichia coli
in acridine orange is influenced by the composition of the containing vessel, and after high kill the variance between replicate suspensions is greater than attributable solely to sampling and plating. Addition of agar minimizes both phenomena, but a higher illumination dose is required to produce the same degree of killing.
Temperature Sensitivity of Maltose Utilization and Lambda Resistance in
Escherichia coli
B
Authors: Ronen A. , Raanan-Ashkenazi Orina
Published: January 2020

Escherichia coli
B strains that have acquired the
malB
region from
E. coli
K-12 are able to utilize maltose and to adsorb phage lambda when grown at 30 C, but when grown at 40 C they do not absorb phage lambda and are devoid of amylomaltase activity. These Mal
ts
Lam
ts
cells can be mutated or transduced to become able to grow on maltose at 40 C, but they still have no detectable amylomaltase activity nor functional lambda receptors at that temperature. This Mal
40
phenotype is governed by a gene located near or at
malA
. It is suggested that the temperature sensitivity of both characters results from a defect in
malT
. However, transduction of
malA
from
E. coli
B to
E. coli
K-12 results in a wild-type phenotype, whereas
E. coli
B cells that have acquired
malA
from
E. coli
K-12 donors are still temperature sensitive for both amylomaltase and lambda-receptor production.
Minor Threonine Dehydratase Encoded Within the Threonine Synthetic Region of
Bacillus subtilis
Authors: Vapnek Daniel , Greer Sheldon
Published: January 2020

Challenging auxotrophs on metabolites that are precursors of a biosynthetic step involving a mutated enzyme has revealed a new class of suppressor mutations which act by derepressing a minor enzyme activity not normally detected in the wild-type strain. These indirect, partial suppressor mutations which allow isoleucine auxotrophs to grow on homoserine or threonine have been analyzed to determine their effect on enzymes involved in the biosynthesis of these amino acids. It has been found that one class of these suppressor mutations (
sprA
) leads to the derepression of homoserine kinase, homoserine dehydrogenase, and a minor threonine dehydratase that is not sufficiently active to be detected in the wild-type strain. The gene encoding this second threonine dehydratase activity has been found to be located between the structural genes for homoserine kinase and homoserine dehydrogenase. The results of these experiments indicate that plating of auxotrophs on precursors of a biosynthetic step involving mutated enzymes could prove to be a valuable method for the detection of regulatory mutants as well as a possible tool in studying the evolution of biochemical pathways.
Cell Division and Prophage Induction in
Escherichia coli
: Studies of Nucleotide Levels
Authors: Ruff W. , Kirby E. P. , Goldthwait D. A.
Published: January 2020

Cell division and prophage repression in the
Escherichia coli
mutant, T-44, are very sensitive to the levels of certain purine and pyrimidine derivatives in the media. The hypothesis that a change in the level of an adenine derivative in the small molecule pool of this strain was responsible for prophage induction and filament formation was tested. The nucleoside triphosphate pools in T-44 and C-600 nonlysogenic and lysogenic strains were labeled in experiments with
32
P and
33
P. Cultures were mixed, and the nucleotides were isolated. When adenine was present, the level of adenosine triphosphate (ATP) in T-44 compared to C-600 (as indicated by the isotope ratio) was increased up to twofold. Most of the other nucleotides increased but not to the same degree. In the lysogenic strain guanosine triphosphate and deoxycytidine triphosphate showed increases comparable to ATP, whereas increases noted in the deoxynucleotides in T-44 ± λ with adenine present were less. In experiments where T-44 and C-600 were incubated with
3
H- and
14
C-adenine, the levels of several compounds, including ATP, were slightly elevated in T-44. The combined data suggest that cultures of T-44 ± λ, grown in the presence of adenine, show a preferential increase in the level of ATP when compared to C-600 ± λ, but the increase in relation to the other nucleotides is less than twofold. In the experiment with
3
H- and
14
C-adenine, the level of inosine was found to be increased in T-44 relative to C-600. Cyclic AMP, when added to cultures of T-44 under various conditions, had no effect on prophage induction. Intracellular and extracellular levels of cyclic AMP in T-44 compared to C-600, incubated with had-acidin, guanosine, and cytidine (HGC) or with HGC plus adenine, were not significantly different. No compelling evidence for altered nucleotide metabolism in T-44 ± λ as a cause of prophage induction or filament formation was obtained.
Regulation of the Pathway for the Degradation of Anthranilate in
Aspergillus niger
Authors: Rao P. V. Subba , Sreeleela N. S. , Premakumar R. , Vaidyanathan C. S.
Published: January 2020

Studies were carried out to determine the factors governing the induction of anthranilate hydroxylase and other enzymes in the pathway for the dissimilation of anthranilate by
Aspergillus niger
(UBC 814). The enzyme was induced by growth in the presence of tryptophan, kynurenine, anthranilate, and, surprisingly, by 3-hydroxyanthranilate, which was not an intermediate in the conversion of anthranilate to 2,3-dihydroxybenzoate. There was an initial lag in the synthesis of anthranilate hydroxylase when induced by tryptophan, anthranilate, and 3-hydroxyanthranilate. Cycloheximide inhibited the enzyme induction. Comparative studies on anthranilate hydroxylase, 2,3-dihydroxybenzoate carboxy-lyase, and catechol 1:2-oxygenase revealed that these enzymes were not coordinately induced by either anthranilate or 3-hydroxyanthranilate. Structural requirements for the induction of anthranilate hydroxylase were determined by using various analogues of anthranilate. The activity of the constitutive catechol oxygenase was increased threefold by exposure to anthranilate, 2,3-dihydroxybenzoate, or catechol. 3-Hydroxyanthranilate did not enhance the levels of catechol oxygenase activity.
Lipid Composition of Some Species of
Arthrobacter
Authors: Shaw N. , Stead D.
Published: January 2020

The lipids from
Arthrobacter crystallopoietes, A. pascens
, and
A. globiformis
were investigated. Each strain contained three glycolipids, a monogalactosyl diglyceride, a digalactosyl diglyceride, and a dimannosyl diglyceride, and traces of triand tetraglycosyl diglycerides. The phospholipids in all three strains consisted of bisphosphatidylglycerol, phosphatidylglycerol, and phosphatidyl
myo
inositol. No evidence could be obtained for the occurrence of mannophosphoinositides. Analysis of the fatty acids by gas-liquid chromatography showed that they are predominantly C
15:0
anteiso
and C
17:0
anteiso
compounds. No significant differences were observed in the composition of lipids extracted from homogeneous cell preparations of the rod and sphere forms of
A. crystallopoietes
.
Taxonomy of Marine Bacteria: the Genus
Beneckea
Authors: Baumann Paul , Baumann Linda , Mandel M.
Published: January 2020

One-hundred-and-forty-five isolates of marine origin were submitted to an extensive physiological, nutritional, and morphological characterization. All strains were gram-negative, facultatively anaerobic, straight or curved rods which were motile by means of flagella. Glucose was fermented with the production of acid but no gas. Sodium but no organic growth factors were required. None of the strains were able to denitrify or fix molecular nitrogen. The results of nutritional and physiological tests were submitted to a numerical analysis. On the basis of phenotypic similarity, nine groups were established. These groups could be distinguished from one another by multiple, unrelated, phenotypic traits. Six groups which had deoxyribonucleic acid (DNA) containing 45 to 48 moles per cent guanine plus cytosine (GC) were assigned to a redefined genus
Beneckea
. All of the strains in this genus, when grown in liquid medium, had a single, polar flagellum. When grown on a solid medium, many strains had peritrichous flagella. Two groups were similar to previously described species and were designated
B. alginolytica
and
B. natriegens
. The remaining four groups were designated
B. campbellii, B. neptuna, B. nereida
, and
B. pelagia
. An additional group of phenotypically similar strains having the properties of the genus
Beneckea
was not included in the numerical analysis. These strains were readily separable from species of this genus and were designated
B. parahaemolytica
. Of the remaining groups, one was identified as
Photobacterium fischeri
. The other group (B-2) which had about 41 moles% GC content in its DNA could not be placed into existing genera.
Stability of Penicillinase Plasmids in
Staphylococcus aureus
Authors: Johnston L. H. , Dyke K. G. H.
Published: January 2020

The isolation of mutants of
Staphylococcus aureus
that are affected in the stability of penicillinase plasmids is described. One mutation is plasmid borne and results in nonreplication of the plasmid at 42 C. A second type of mutation is host-borne and gives rise to instability of both
mcr
I
and
mcr
II
penicillinase plasmids but not a tetracycline-resistant plasmid.
Regulation of Tyrosine Biosynthesis in
Escherichia coli
K-12: Isolation and Characterization of Operator Mutants
Authors: Mattern Ina E. , Pittard J.
Published: January 2020

Mutant strains of
Escherichia coli
have been isolated in which the synthesis of two of the enzymes involved in tyrosine biosynthesis, 3-deoxy-
d
-arabinoheptulosonic acid-7 phosphate synthetase (tyr) and chorismate mutase T-prephenate dehydrogenase, is partially constitutive. The mutations involved are closely linked to
aroF
and
tyrA
, the structural genes of these enzymes. The gene in which the mutations occur has been designated
aroK
, and the gene sequence is
aroK, aroF, tyrA
. In
aroK
+
/
aroK
diploids, the
aroK
allele only affects the structural genes in the cis position. The mutant allele
aroK
is not recessive to
aroK
+
and
aroK/aroK
+
strains exhibit the
aroK
phenotype of resistance to 4-aminophenylalanine. It is proposed that
aroK
is an operator locus for an
aroF tyrA
operon.