bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Biochemical and Immunological Study of Malic Enzyme from Two Species of Lactic Acid Bacteria: Evolutionary Implications
Authors: London Jack , Meyer Eleanor Y. , Kulczyk Sandra
Published: January 2020

Representatives of bothStreptococcus faecalisandLactobacillus caseiproduce isofunctional malic enzymes. All 10 strains ofS. faecalistested could be induced to synthesize malic enzyme and readily adapted to growth on malate. Although 17 of 21L. caseistrains could be induced to produce malic enzyme, only 9 of 14 strains tested grew at the expense of malate. A comparison of catalytic and regulatory properties suggested that the malic enzymes fromS. faecalisandL. caseiwere very similar. Immunological analyses showed that the numerous similarities in function actually reflected partial protein homologies; however, two distinct forms of the malic enzyme were detected among different strains ofL. caseiby immunochemical and serological procedures. The division ofL. caseiinto two subgroups based on the immunological type of malic enzyme synthesized corresponds to two subspecies currently recognized by microbial taxonomists.
Phenoloxidase Activity and Fruiting Body Formation in
Schizophyllum commune
Authors: Leonard Thomas J.
Published: January 2020

Studies of induced haploid fruiting in the Basidiomycete
Schizophyllum commune
suggested that polyphenoloxidase enzymes may participate in the formation of fruiting bodies. Reported inhibitors of phenoloxidases were found to affect both the activity of these enzymes and the fruiting response. Fertile mycelia were found to give a positive Bavendamm reaction in situ, and cell-free extracts from fertile mycelia exhibited polyphenoloxidase activity when studied spectrophotometrically. Sterile mycelia, on the other hand, were devoid of these activities. Various kinds of mutant homo- and dikaryotic mycelia were studied, and the results suggested a correlation between phenoloxidase activity and fruiting body formation in
S. commune
.
Genetic Heterogeneity in
Streptococcus mutans
Authors: Coykendall Alan L.
Published: January 2020

The genetic homogeneity among eight cariogenic strains of
Streptococcus mutans
was assessed by deoxyribonucleic acid (DNA)-DNA reassociation experiments. DNA species were extracted from strains GS5, Ingbritt, 10449, FAl, BHT, E49, SLl, and KlR. Labeled DNA (
14
C-DNA) was extracted from strains 10449, FAl, and SLl. Denatured
14
C-DNA fragments were allowed to reassociate, i.e., form hybrid duplexes, with denatured DNA immobilized on membrane filters incubated in 0.45
m
NaCl-0.045
m
sodium citrate at 67 or 75 C. At 67 C, 10449
14
C-DNA reassociated extensively only with GS5 and Ingbritt DNA. FAl
14
C-DNA hybridized extensively only with BHT DNA, and SLl
14
C-DNA reassociated with KlR and E49 DNA. DNA which hybridized extensively at 67 C also reassociated to a high degree at 75 C. Thermal elution of
14
C-FAl-BHT duplexes showed that the hybrid duplexes were thermostable. The results indicate that
S. mutans
is a genetically heterogeneous species. The strains studied can be divided into three (possibly four) genetic groups, and these groups closely parallel antigenic groups.
Maintenance and Exchange of the Aromatic Amino Acid Pool in
Escherichia coli
Authors: Brown K. D.
Published: January 2020

The pool of phenylalanine, tyrosine, and tryptophan is formed in
Escherichia coli
K-12 by a general aromatic transport system [Michaelis constant (
K
m
) for each amino acid approximately 5 × 10
−7
m
] and three further transport systems each specific for a single aromatic amino acid (
K
m
for each amino acid approximately 2 × 10
−6
m
, reference 3). When the external concentration of a particular aromatic amino acid is saturating for both classes of transport system, the free amino acid pool is supplied with external amino acid by both systems. Blocking the general transport system reduces the pool size by 80 to 90% but does not interfere with the supply of the amino acid to protein synthesis. If, however, the external concentration is too low to saturate specific transport, blocking general transport inhibits the incorporation of external amino acid into protein by about 75%. It is concluded that the amino acids transported by either class of transport system can be used for protein synthesis. Dilution of the external amino acid or deprivation of energy causes efflux of the aromatic pool. These results and rapid exchange observed between pool amino acid and external amino acids indicate that the aromatic pool circulates rapidly between the inside and the outside of the cell. Evidence is presented that this exchange is mediated by the aromatic transport systems. Mutation of
aroP
(a gene specifying general aromatic transport) inhibits exit and exchange of the small pool generated by specific transport. These findings are discussed and a simple physiological model of aromatic pool formation, and exchange, is proposed.
Induction Specificity and Catabolite Repression of the Early Enzymes in Camphor Degradation by
Pseudomonas putida
Authors: Hartline Richard A. , Gunsalus I. C.
Published: January 2020

The ability of bornane and substituted bornanes to induce the early enzymes for
d
(+)-camphor degradation and control of these enzymes by catabolite repression were studied in a strain of a
Pseudomonas putida
. Bornane and 20 substituted bornane compounds showed induction. Of these 21 compounds, bornane and 8 of the substituted bornanes provided induction without supporting growth. Oxygen, but not nitrogen, enhanced the inductive potency of the unsubstituted bornane ring. All bornanedione isomers caused induction, and those with substituents on each of the three consecutive carbon atoms, including the methyl group at the bridgehead carbon, showed induction without supporting growth. Although it was not possible to obtain experimental data for a case of absolute gratuitous induction by compounds not supporting growth, indirect evidence in support of gratuitous induction is presented. It is proposed that the ability of
P. putida
to tolerate the unusually high degree of possible gratuitous induction observed for camphor catabolism may be related to the infrequent occurrence of bicyclic ring structures in nature. Survival of an organism with a broad specificity for gratuitous induction is discussed. Glucose and succinate, but not glutamate, produced catabolite repression of the early camphor-degrading enzymes. Pathway enzymes differ in their degree of sensitivity to succinate-provoked catabolite repression. The ability of a compound to produce catabolite repression is not, however, directly related to the duration of the lag period (diauxic lag) between growth on camphor and growth on the repressing compound.
Dark Repair of Ultraviolet-Irradiated Deoxyribonucleic Acid by Bacteriophage T4: Purification and Characterization of a Dimer-Specific Phage-Induced Endonuclease
Authors: Friedberg Errol C. , King John J.
Published: January 2020

The purification and properties of an ultraviolet (UV) repair endonuclease are described. The enzyme is induced by infection of cells of
Escherichia coli
with phage T4 and is missing from extracts of cells infected with the UV-sensitive and excision-defective mutant T4V
1
. The enzyme attacks UV-irradiated deoxyribonucleic acid (DNA) containing either hydroxymethylcytosine or cytosine, but does not affect native DNA. The specific substrate in UV-irradiated DNA appears to be pyrimidine dimer sites. The purified enzyme alone does not excise pyrimidine dimers from UV-irradiated DNA. However, dimer excision does occur in the presence of the purified endonuclease plus crude extract of cells infected with the mutant T4V
1
.
Extracellular Transglucosylase and α-Amylase of
Streptococcus equinus
Authors: Boyer Ernest W. , Hartman Paul A.
Published: January 2020

Culture filtrates of
Streptococcus equinus
1091 contained α-amylase and transglucosylase. The effects of calcium carbonate, age of inoculum, concentration of maltose, and duration of the fermentation on α-amylase and transglucosylase production were determined. The extracellular α-amylase was purified 48-fold and was free of transglucosylase activity. The α-amylase (amylose substrate) required Cl
−
for maximum activity; ethylenediaminetetraacetic acid (EDTA) partially inhibited activity, but CaCl
2
prevented EDTA inhibition. The temperature optimum was 38 C at
p
H 7.0, and the
p
H optimum was 7.0 at 37 C in the presence of CaCl
2
. Predominant final products of amylose hydrolysis, in order of decreasing prevalence, were maltose, maltotriose, maltotetraose, and glucose. The α-amylase showed no evidence of multiple attack. The extracellular transglucosylase was purified 27-fold, but a small amount of α-amylase remained. Transglucosylase activity (amylose substrate) was not increased in the presence of CaCl
2
. The temperature optimum was 37 C at
p
H 6.5, and the
p
H optimum was 6.0 at 37 C. Carbohydrates that served as acceptors for the transglucosylase to degrade amylose were, in order of decreasing acceptor efficiency:
d
-glucose,
d
-mannose,
l
-sorbose, maltose, sucrose, and trehalose. The extracellular transglucosylase of
S. equinus
1091 synthesized higher maltodextrins in the medium when the cells were grown in the presence of maltose.
Purification and Properties of
l
-Asparaginase from
Serratia marcescens
Authors: Boyd John W. , Phillips Arthur W.
Published: January 2020

The purification and properties of a tumor inhibitory
l
-asparaginase from
Serratia marcescens
are described. The following properties of the enzyme were examined: kinetics of the enzyme reaction, catalytic activity as a function of
p
H, boundary sedimentation velocity, electrophoresis on polyacrylamide gel, immuno-electrophoresis against homologous and heterologous antisera, immunodiffusion, blood clearance rate in mice, and inhibition of the 6C3HED lymphoma in C3H mice. Complete regression of this tumor was obtained with a smaller dose of the enzyme from
S. marcescens
than with enzyme from
Escherichia coli
. The reason for this difference was not evident from a comparison of several properties of the two enzymes.
Morphological Changes and Antibiotic-Induced Thermal Resistance in Vegetative Cells of
Bacillus subtilis
Authors: Dul Michael J. , McDonald William C.
Published: January 2020

The morphology and thermal resistance of vegetative cells of
Bacillus subtilis
W168 were examined after growth at 37 and 53 C. Vegetative cells grown at 37 C exhibited a typical trilaminar morphology, whereas cells grown at 53 C exhibited a cell wall which was apparently thicker and more loosely organized and had a poorly defined periphery. A concurrent increase in thermal resistance to a heat shock of 60 C occurs with the change in cell wall morphology. The change to the aberrant cell wall form, or its reversal to the normal form, is always accompanied by the gain or the loss of thermal resistance, respectively. The inhibition of protein synthesis by chloramphenicol has little effect upon the acquisition of thermal resistance at 53 C. Addition of the disaccharide pentapeptide subunit to the cell wall peptidoglycan is apparently essential to growth at 53 C and the acquisition of thermal resistance, since both growth and thermal resistance are inhibited by bacitracin. Two antibiotics, penicillin and cycloserine, which inhibit the final cross-linking of the cell wall peptidoglycan at two separate points, do not affect the acquisition of thermal resistance at 53 C. These same antibiotics induce a high degree of thermal resistance at 37 C. It is proposed that a change in the cell wall structure is related to an increased thermal resistance.
Specificity of a Catabolic Pathway—a Lesson Learned from Indirect Assays
Authors: Ribbons D. W. , Ohta Y. , Higgins I. J.
Published: January 2020

Studies with purified orcinol hydroxylase suggest that, contrary to previous conclusions, the enzymes of the orcinol pathway cannot transform analogous compounds to common metabolites. The substrate analogues of orcinol uncouple electron flow from reduced nicotinamide adenine dinucleotide to oxygen from the hydroxylation reaction catalyzed by orcinol hydroxylase.
Preparation of Biologically Active Ribosomal Subunits from Fungal Spores
Authors: Van Etten James L.
Published: January 2020

Ribosomal subunits were prepared from fungal spore ribosomes and reassociated to yield biologically active ribosomes.
Elimination of the Acid Fastness but not the Gram Positivity of Leprosy Bacilli After Extraction with Pyridine
Authors: Fisher Clark A. , Barksdale Lane
Published: January 2020

Bacilli from a number of tissues excised from cases of lepromatous and borderline leprosy, unlike mycobacteria, were found to lose their acid-fastness after treatment with pyridine.
Alkane Oxidation by a Particulate Preparation from
Candida
Authors: Liu Chao-Min , Johnson Marvin J.
Published: January 2020

The oxidation of decane by a cell-free particulate preparation from
Candida intermedia
was studied. Decane is oxidized to decanoate via decanol and decanaldehyde. Oxidation of decane to decanol requires molecular oxygen. Decanol is oxidized to decanaldehyde by a nicotinamide adenine dinucleotide-linked dehydrogenase differing greatly in specificity from ordinary yeast alcohol dehydrogenase. Decanaldehyde is oxidized to decanoate by a nicotinamide adenine dinucleotide-linked dehydrogenase that oxidizes long-chain aldehydes but not short-chain aldehydes. The enzymes that oxidize decane, decanol, and decanaldehyde are all induced when decane is present in the medium. These enzymes are apparently located in the cell membrane.
Erythromycin-Inducible Resistance in
Staphylococcus aureus:
Requirements for Induction
Authors: Weisblum B. , Siddhikol C. , Lai C. J. , Demohn V.
Published: January 2020

At least two functionally different types of ribosomes are found in strains of
Staphylococcus aureus
which display “dissociated” resistance to erythromycin. One type of ribosome is found under conditions of growth in ordinary nutrient broth, and the second is formed during growth in the presence of erythromycin. In these strains, erythromycin acts as an inducer of resistance to three different classes of inhibitors of the 50
S
ribosomal subunit—the macrolides, lincosamides, and streptogramin B-type antibiotics. The optimal inducing concentration of erythromycin is between 10
−8
and 10
−7
m
. Concentrations as low as 10
−9
m
can produce a 10-fold increase in resistant cells over the uninduced, background level, whereas concentrations greater than 10
−7
m
block induction owing to inhibition of protein synthesis. Resistant cells begin to appear within 5 to 10 min after addition of erythromycin (to 10
−7
m
), and within 40 min (i.e., about one generation) more than 90% of the entire culture is resistant to erythromycin as well as to lincomycin and vernamycin B
α
. A resistant culture becomes sensitive if grown for 90 min in the absence of erythromycin. The process of induction is inhibited by chloramphenicol and streptovaricin, which inhibit protein and ribonucleic acid synthesis, respectively, but not by novobiocin, which inhibits deoxyribonucleic acid synthesis. Resistant cells produced in this manner fail to concentrate
14
C-erythromycin and
14
C-lincomycin, but not
14
C-chloramphenicol. Constitutively erythromycin-resistant strains which do not require the presence of erythromycin for expression of resistance can be selected on media containing antibiotics which belong to any one of the three classes. Two patterns of constitutive resistance have been found. These are (i) generalized constitutive resistance—which involves resistance in the absence of erythromycin to
all
members of each of the three cited classes of 50
S
subunit inhibitors which were tested, and (ii) partial constitutive resistance—which involves different degrees of resistance, in the absence of erythromycin, to various members of the three classes. Several different patterns of variable constitutivity are possible. 50
S
ribosomal subunits isolated from induced or constitutively resistant cells show decreased ability to bind erythromycin and lincomycin, and possible enzymatic inactivation of these antibiotics has been rigorously excluded. The induced change, therefore involves modification of ribosome structure rather than modification of the antibiotic.
Chemical Detection of Microbial Prey by Bacterial Predators
Authors: Chet Ilan , Fogel Sam , Mitchell Ralph
Published: January 2020

A motile, predacious bacterium which degraded
Pythium debaryanum
was strongly attracted to substances released into the medium by the fungus. A nonpredacious bacterium was not attracted to these substances. The predator bacterium was specifically attracted to cellulose and its oligomers which are known to be components of the cell wall of
Pythium
. Ethanol inhibited chemotaxis of the bacterium without affecting either its motility or its ability to degrade cellulose. A second predacious bacterium was isolated for the alga,
Skeletonema costatum
. The role of chemoreception in the detection of microbial prey by bacterial predators in natural habitats is discussed.
Occurrence of Pyruvic Acid in Capsular Polysaccharides from VariousKlebsiellaSpecies
Authors: Gormus B. J. , Wheat Robert W. , Porter John F.
Published: January 2020

Capsular polysaccharide materials from several different klebsiella serotypes were demonstrated to contain an α-keto acid characterized as pyruvic acid. Linkage to the capsular polysaccharides was shown to be acid labile and alkali stable, suggesting ketosidic rather than ester linkages.
Interactions of Alkaline Phosphatase and the Cell Wall of
Pseudomonas aeruginosa
Authors: Cheng K.-J. , Ingram J. M. , Costerton J. W.
Published: January 2020

Spheroplasts prepared by lysozyme treatment of cells of
Pseudomonas aeruginosa
, suspended in 20% sucrose or 0.2
m
MgCl
2
, were examined in detail. Preparation of spheroplasts in the presence of 0.2
m
Mg
2+
released periplasmic alkaline phosphatase, whereas preparation in the presence of 20% sucrose did not, even though untreated cells released phosphatase when suspended in sucrose in the absence of lysozyme. Biochemical characterizations of the sucrose-lysozyme preparations indicated that lysozyme mediated a reassociation of the released phosphatase with the spheroplasts. In addition, the enzyme released from whole cells suspended in 20% sucrose (which represents 20 to 40% of the cell-bound phosphatase) reassociates with the cells in the presence of lysozyme. Electron microscopic examinations of various preparations revealed that phosphatase released in sucrose reassociated with the external cell wall layers in the presence of lysozyme, that sucrose-lysozyme prepared spheroplasts did not dissociate phosphatase which remained in the periplasm of sucrose-washed cells, and that phosphatase was never observed to be associated with the cytoplasmic membrane. A model to account for the binding of
P. aeruginosa
alkaline phosphatase to the internal portion of the tripartite layer of the cell wall rather than to the cytoplasmic membrane or peptidoglycan layer is presented.
Petite Mutation in Yeast
Authors: Goldring Elizabeth S. , Grossman Lawrence I. , Marmur Julius
Published: January 2020

A series of petite mutants of
Saccharomyces cerevisiae
, generated after treatment for various times with ethidium bromide, was isolated, and the mitochondrial deoxyribonucleic acid size for each member was estimated. It was found that, as the treatment time with ethidium bromide was increased, the mitochondrial deoxyribonucleic acid isolated from the petite series was increasingly reduced in size.
Growth Rate of
Escherichia coli
at Elevated Temperatures: Limitation by Methionine
Authors: Ron Eliora Z. , Davis Bernard D.
Published: January 2020

When
Escherichia coli
growing in minimal medium is shifted from 37 C to any temperature in the range 40 to 45 C, the growth rate immediately assumes a new, lower value, characteristic of that temperature. The decrease is shown to be due, in several strains, to decreased activity of the first enzyme of the methionine pathway, homoserine trans-succinylase, which thus appears to be more heat-sensitive than any other essential enzyme in the cell. This sensitivity does not involve progressive denaturation of the enzyme; rather, the response to a shift of temperature, in either direction, is immediate and reversible.
Deoxyribonucleic Acid Transferred from Ultraviolet-Irradiated Excision-Defective Hfr Cells of
Escherichia coli
K-12
Authors: Wilkins B. M. , Hollom S. E. , Rupp W. D.
Published: January 2020

Deoxyribonucleic acid (DNA) transfer from
3
H-thymine-labeled Hfr cells has been measured by determining the amount of radioactivity remaining after selective lysis of the donor cells in the mating mixture. DNA transfer was less effectively reduced by ultraviolet irradiation of excision-defective Hfr cells than was the yield of recombinants. The buoyant density of DNA transferred from unirradiated and irradiated Hfr cells was equivalent to that of double-stranded DNA. Mating-dependent DNA synthesis in the recipient has been measured by mating Hfr cells deficient in thymidine kinase with irradiated thymine-requiring F
−
cells in the presence of
3
H-thymine. The extent of such DNA synthesis approximated the amount of DNA transferred from unirradiated donors. Neither DNA transfer nor mating-dependent DNA synthesis could be reliably measured when both parents were irradiated. It is proposed that transferred Hfr DNA is replicated in the recipient and that this replication still occurs when the Hfr DNA contains dimers.
Location of Three Genes Concerned with the Conversion of 2, 3-Dihydroxybenzoate into Enterochelin in
Escherichia coli
K-12
Authors: Luke R. K. J. , Gibson F.
Published: January 2020

Mutants of
Escherichia coli
K-12 unable to synthesize the iron-sequestering compound, enterochelin, from 2,3-dihydroxybenzoate have been isolated and divided into three classes on the basis of tests for enzymatic complementation. The genes affected (designated
entD, entE
, and
entF
) have been mapped by cotransduction and are located at about minute 14 on the
E. coli
genome. They were found to be closely linked to other genes (
entA, entB
, and
entC
) concerned with enterochelin biosynthesis and a gene (
fep
) concerned with the uptake of the iron-enterochelin complex. No detectable diffusible intermediate in the formation of enterochelin from 2,3-dihydroxybenzoate was formed by cell extracts of mutants carrying mutations in the
entD, entE
, or
entF
genes.
2-Keto-3-Deoxygluconate, an Intermediate in the Fermentation of Gluconate by Clostridia
Authors: Bender R. , Andreesen J. R. , Gottschalk G.
Published: January 2020

Five clostridial species were found to ferment gluconate via 2-keto-3-deoxygluconate which subsequently is phosphorylated to yield 2-keto-3-deoxy-6-phosphogluconate (KDPG). This compound is then cleaved by KDPG aldolase.
Bicarbonate Requirement for Elimination of the Lag Period of
Hydrogenomonas eutropha
Authors: Repaske Roy , Ambrose Carol A. , Repaske Anne C. , De Lacy Margaret L.
Published: January 2020

Carbon dioxide and oxygen concentrations have a profound effect on the lag period of chemoautotrophically grown
Hydrogenomonas eutropha
. Minimum lag periods and high growth rates were obtained in shaken flask cultures with a prepared gas mixture containing 70% H
2
, 20% O
2
, and 10% CO
2
. However, excessively long lag periods resulted when the same gas mixture was sparged through the culture. The lag period was shortened in sparged cultures by decreasing both the pO
2
and the pCO
2
, indicating that gas medium equilibration had not occurred in shaken cultures. The lag period was completely eliminated at certain concentrations of O
2
and CO
2
. The optimum pO
2
was 0.05 atm, but the optimum pCO
2
varied according to the
p
H of the medium and physiological age of the inoculum. At
p
H 6.4, the pCO
2
required to obtain immediate growth of exponential, postexponential, and stationary phase inocula at equal specific rates was 0.02, 0.05, and 0.16 atm, respectively. With each 0.3-unit increase in the
p
H of the medium, a 50% decrease in the CO
2
concentration was needed to permit growth to occur at the same rate. The pCO
2
changes required to compensate for the
p
H changes of the medium had the net effect of maintaining a constant bicarbonate ion concentration. Initial growth of
H. eutropha
was therefore indirectly related to pCO
2
and directly dependent upon a constant bicarbonate ion concentration.
Isoleucine Hydroxamate, an Isoleucine Antagonist
Authors: Kisumi Masahiko , Komatsubara Saburo , Sugiura Masaki , Chibata Ichiro
Published: January 2020

Isoleucine hydroxamate (Ile·Hdx) was found to inhibit the growth of
Serratia marcescens
and to antagonize isoleucine. At a low concentration of Ile·Hdx, at which the growth of the wild strain was completely inhibited, the growth of an isoleucine auxotroph was not inhibited in the medium containing a limiting amount of
d
-threonine as the isoleucine source. At a higher concentration, this antagonist exhibited a considerable inhibitory effect on the growth of the auxotroph. Ile·Hdx showed the same inhibitory effect as isoleucine on
l
-threonine dehydratase activity at the concentrations 10 times those of isoleucine. Ile·Hdx caused also derepression of isoleucine-valine biosynthetic enzymes and the derepression was overcome by isoleucine. These results indicate the Ile·Hdx causes growth inhibition by its effects on isoleucine metabolism.
Protease Activities During the Course of Sporulation in
Bacillus subtilis
Authors: Prestidge Louise , Gage Vivian , Spizizen John
Published: January 2020

Three proteolytic enzymes have been isolated from sporulating cultures of
Bacillus subtilis
. These activities were, respectively, a protease inhibited by ethylenediaminetetraacetic acid (EDTA) but not phenylmethylsulfonyl fluoride (PMSF), a protease active on both protein and ester substrates, and an ester-active enzyme with low activity on proteins. The latter two enzymes were inhibited by PMSF but not by EDTA. The specific activity of each was determined both intra- and extra-cellularly during growth and sporulation in a single-defined medium. All three enzymes were shown to exhibit a rapid increase in specific activity at a time coinciding with the appearance of refractile bodies in cells.
Lethal Synthesis of Methylglyoxal by
Escherichia coli
During Unregulated Glycerol Metabolism
Authors: Freedberg W. B. , Kistler W. S. , Lin E. C. C.
Published: January 2020

In
Escherichia coli
K-12, the conversion of glycerol to triose phosphate is regulated by two types of control mechanism: the rate of synthesis of glycerol kinase and the feedback inhibition of its activity by fructose-1,6-diphosphate. A strain which has lost both control mechanisms by successive mutations, resulting in the constitutive synthesis of a glycerol kinase no longer sensitive to feedback inhibition, can produce a bactericidal factor from glycerol. This toxic factor has been identified by chemical and enzymological tests as methylglyoxal. Methylglyoxal can be derived from dihydroxyacetone phosphate through the action of an enzyme which is present at high constitutive levels in the extracts of the mutant as well as that of the wild-type strain. Nine spontaneous mutants resistant to 1 m
m
exogenous methylglyoxal have been isolated. In all cases the resistance is associated with increased levels of a glutathione-dependent enzymatic activity for the removal of methylglyoxal. Methylglyoxal-resistant mutants derived from the glycerol-sensitive parental strain also became immune to glycerol.
Hyphal Wall Synthesis in
Aspergillus nidulans
: Effect of Protein Synthesis Inhibition and Osmotic Shock on Chitin Insertion and Morphogenesis
Authors: Katz Dvorah , Rosenberger R. F.
Published: January 2020

Pulse-labeling with
N
-[
acetyl
-
3
H
] glucosamine and radioautography were used to follow the sites of chitin incorporation in hyphae of an
Aspergillus nidulans
mutant blocked in amino sugar synthesis. Growing hyphae incorporated
N
-acetylglucosamine almost exclusively at the tip. Cycloheximide addition greatly increased the label in subapical regions of the hyphae and reduced that at the tip. This effect of cycloheximide was immediate, could be reversed by removing the inhibitor, and did not appear to be due to chitin turnover. A similar change from apical to subapical
N
-acetylglucosamine incorporation occurred after hyphae were subjected to an osmotic shock which did not inhibit protein synthesis. The two treatments induced morphogenetic changes in the hyphae which produced abnormally large numbers of branches and septa.
Neutral Lipids in the Study of Relationships of Members of the Family
Micrococcaceae
Authors: Morrison Susan J. , Tornabene T. G. , Kloos Wesley E.
Published: January 2020

The organisms studied were those of the family
Micrococcaceae
which cannot participate in genetic exchange with
Micrococcus luteus
and those whose biochemical and physiological characteristics appear to bridge the genera
Staphylococcus
and
Micrococcus
. The hydrocarbon compositions of
M. luteus
ATCC 4698 and
Micrococcus
sp. ATCC 398 were shown to be similar to those previously reported for many
M. luteus
strains, consisting of isomers of branched monoolefins in the range C25 to C31. However,
Micrococcus
sp. ATCC 398 differed somewhat by having almost all C29 isomers (approximately 88% of the hydrocarbon composition).
Micrococcus
spp. ATCC 401 and ATCC 146 and
M. roseus
strains ATCC 412, ATCC 416, and ATCC 516 contained the same type of hydrocarbon patterns, but the predominant hydrocarbons were within a lower distribution range (C23 to C27), similar to
Micrococcus
sp. ATCC 533 previously reported. The chromatographic profile and carbon range of the hydrocarbons of an atypical strain designated
M. candicans
ATCC 8456 differed significantly from the hydrocarbon pattern presented above. The hydrocarbons were identified as branched and normal olefins in the range C16 to C22. Studies of several different strains of staphylococci revealed that these organisms do not contain readily detectable amounts of aliphatic hydrocarbons. The members of the family
Micrococcaceae
have been divided into two major groups based on the presence or absence of hydrocarbons. With the exception of
M. candicans
ATCC 8456, this division corresponded to the separation of these organisms according to their deoxyribonucleic acid compositions.
Phenethyl Alcohol as a Suppressor of theEnvAPhenotype Associated with theenvAGene inEscherichia coliK-12
Authors: Normark Staffan
Published: January 2020

InEscherichia coliK-12 theenvAgene was previously shown to mediate chain formation and a decreased tolerance to several antibacterial agents. Phenethyl alcohol at low concentrations has now been found to increase the tolerance to actinomycin D, ampicillin, rifampin, and gentian violet in strains containingenvA. The increased tolerance to gentian violet was correlated to a decreased uptake of the dye. A phenotype suppression of chain formation and colony morphology inenvAmutants was also obtained. Except for an increase in palmitic acid, chemical analysis revealed no differences between anenvAand its wild-type strain in the lipopolysaccharide part of the envelope. However, a decrease in the amount of phosphatidylglycerol and a C18: 1 fatty acid was observed in the extractable lipids of a strain containingenvA. Growth in the presence of phenethyl alcohol reversed the changes in fatty acid and the phospholipid composition. Phenethyl alcohol was found to cause an immediate but transient inhibition of ribonucleic acid synthesis. It is suggested that this inhibition affects the penetrability barrier of the outer cell envelope layers in strains containingenvA.
Nystatin-Resistant Mutants of Yeast: Alterations in Sterol Content
Authors: Woods Robin A.
Published: January 2020

Mutants of the genes
nys1
and
nys3
differ from sensitive strains (
nys
+
) in their sterol content. Ultraviolet absorption spectra of the nonsaponifiable material extracted from cells of
nys
+
demonstrated the presence of ergosterol and 24(28)-dehydroergosterol. In
nys1
mutants, the spectrum suggests the presence of a new sterol. The absorption spectrum of extracts from
nys3
mutants indicates absence of both ergosterol and 24(28)-dehydroergosterol and presence of another new sterol. Conversion of
nys
+
and
nys3
to petite results in loss of 24(28)-dehydroergosterol in the former and the new sterol in the latter, whereas the new sterol in
nys1
is only reduced. The sterols in ethanol-grown cells of all genotypes are essentially the same as is found for growth on glucose. With the exception of
nys3
grown on ethanol, the mutants do not appear to be at a disadvantage compared to wild type.
Effect of 4-Azaleucine upon Leucine Metabolism in
Salmonella typhimurium
Authors: Stieglitz B. , Calvo J. M.
Published: January 2020

dl
-4-Azaleucine (5 × 3
−3
m
) added to exponentially growing cells of
Salmonella typhimurium
resulted in an abrupt cessation of growth lasting 4 to 8 hr followed by a resumption of division. The transitory nature of inhibition was not due to the instability or modification of the analogue or to a derepression of leucine-forming enzymes. Of many compounds tested, leucine served most efficiently to reverse 4-azaleucine-induced inhibition. Inhibition of growth can be explained by the fact that 4-azaleucine inhibits α-isopropylmalate synthase, the first enzyme unique to leucine biosynthesis. The analogue was a poor inhibitor of both the transamination of α-ketoisocaproate to leucine and the charging of leucine to transfer ribonucleic acid. With a leucine auxotroph starved for leucine, the analogue was incorporated into protein specifically in place of leucine. Such incorporation was accompanied by the death of almost all of the cells.
Phosphoglucomutase Mutants of
Escherichia coli
K-12
Authors: Adhya Sankar , Schwartz Maxime
Published: January 2020

Bacteria with strongly depressed phosphoglucomutase (EC 2.7.5.1) activity are found among the mutants of
Escherichia coli
which, when grown on maltose, accumulate sufficient amylose to be detectable by iodine staining. These
pgm
mutants grow poorly on galactose but also accumulate amylose on this carbon source. Growth on lactose does not produce high amylose but, instead, results in the induction of the enzymes of maltose metabolism, presumably by accumulation of maltose. These facts suggest that the catabolism of glucose-1-phosphate is strongly depressed in
pgm
mutants, although not completely abolished. Anabolism of glucose-1-phosphate is also strongly depressed, since amino acid- or glucose-grown
pgm
mutants are sensitive to phage C21, indicating a deficiency in the biosynthesis of uridine diphosphoglucose or uridine diphosphogalactose, or both. All
pgm
mutations isolated map at about 16 min on the genetic map, between
pur
E and the
gal
operon.
Extent of Host Deletions Associated with Bacteriophage P2-Mediated Education
Authors: Sunshine Melvin G. , Kelly Beatrice
Published: January 2020

A series of independentEscherichia coliK eductants has been isolated and tested to determine the extent of their deletions. The deletions cover the P2 prophage in location H, thehisoperon, a suppressor of therecBCphenotype (sbcB), the gene for gluconate-6-phosphate dehydrogenase (gnd), a locus involved in cell wall synthesis (rfb), and in some cases all or part of genes involved in methylgalactoside uptake (mglP). One end of the deletion, the P2 prophage end, appears to be the same for all eductants. The other end, however, can be located before, within, and after themglPlocus.
Fatty Acid Composition of
Cladosporium resinae
Grown on Glucose and on Hydrocarbons
Authors: Cooney J. J. , Proby C. M.
Published: January 2020

Cladosporium resinae
was grown in submerged cultures on glucose; on Jet-A commercial aviation fuel; and on a series of
n
-alkanes,
n
-decane through
n
-tetradecane. Cell yield was greatest on glucose and least on Jet-A;
n
-alkanes were intermediate. Among
n
-alkanes cell yield decreased as chain length increased, except for
n
-dodecane, which supported less growth than
n
-tridecane or
n
-tetradecane. The total fatty acids of stationary-phase cells were analyzed by gas-liquid chromatography. In all cases the predominant fatty acids were 16:0, 18:1, and 18:2. The fatty acid composition of glucose-grown cells was similar to that of hydrocarbon-grown cells. Cells grown on
n
-tridecane or
n
-tetradecane yielded small amounts of acids homologous to the carbon source, but a similar correlation was not noted for
n
-decane,
n
-undecane, or
n
-dodecane. Cells grown on
n
-undecane or
n
-tridecane contained more odd-carbon fatty acids than cells grown on the other substrates, and the effect was more pronounced in
n
-tridecane-grown cells. Thus, the fatty acids of this organism are derived chiefly from de novo synthesis rather than from direct incorporation of oxidized hydrocarbons. The extent of direct incorporation increases as the chain length of the hydrocarbon growth substrate is increased.
Fatty Acid Composition of
Bifidobacterium
and
Lactobacillus
Strains
Authors: Veerkamp J. H.
Published: January 2020

Normal C
14
, C
16
, and C
18
saturated acids and C
16
and C
18
monoenoic acids are the main fatty acids of nine strains of
Bifidobacterium
. Their lactobacillic acid content was less than 5%.
Lactobacillus
strains contained the same fatty acids as main compounds except for octadecanoic acid, which was present only in very low amounts. Eight of nine
Lactobacillus
strains contained in the stationary phase more than 15% lactobacillic acid. No correlation was observed between the fatty acid composition and other physiological characteristics used in the literature for classification of strains of one genus. Aging of the culture, which involved a decrease of the
p
H, caused a lengthening of the chain length of the fatty acids of
B. bifidum
var.
pennsylvanicus
but only a conversion of octadecenoic to lactobacillic acid in the lactobacilli. Lowering of the temperature of cultivation decreased the chain length of the fatty acids of
B. bifidum
var.
pennsylvanicus. L. lactis
did not show any influence of the temperature on the chain length of the fatty acids. The percentage of unsaturated acids was temperature independent in both organisms.
Growth of
Escherichia coli
on Short-Chain Fatty Acids: Nature of the Uptake System
Authors: Salanitro Joseph P. , Wegener Warner S.
Published: January 2020

Mutants of
Escherichia coli
K-12 which grow on butyrate and valerate were studied with respect to uptake of these substrates. To utilize short-chain and medium-chain fatty acids,
E. coli
must synthesize the β-oxidation enzymes constitutively. In addition, growth on the C
4
and C
5
acids requires a second mutation which permits entry of these substrates. At
p
H 5, both in the parent and mutant strains, butyrate and valerate penetrate as the undissociated acids but appear not to be activated and thus inhibit growth. At
p
H 7, the parent strain is not permeable to the anions, whereas the mutant concentrates these substrates. There appear to be two components of the uptake system, a nonspecific diffusion component and an energy-linked activating enzyme. Two mutant types which take up short-chain fatty acids are described. One synthesizes the uptake system constitutively and is inhibited by 4-pentenoate when cultured on acetate. In the other, the uptake system is inducible, and the strain is pentenoate-resistant when grown on acetate but pentenoate-sensitive when cultured on butyrate or valerate.
Role of Vitamin B6Biosynthetic Rate in the Study of Vitamin B6Synthesis inEscherichia coli
Authors: Dempsey Walter B.
Published: January 2020

Nutritional auxotrophs ofEscherichia colisynthesize vitamin B6compounds at a rate of 1 × 10−10to 2 × 10−10moles per hr per mg (dry weight) of cells when they are suspended in minimal medium lacking their required nutrients. A few auxotrophs have been found to stop or reduce vitamin B6synthesis during such an experiment. These include thiamineless, citrate synthaseless, and pyridoxineless mutants as well as mutants which require four carbon compounds for growth. Glycolaldehyde was found to restore vitamin B6synthesis in the last named of these mutants without restoring normal growth. A class of pyridoxineless mutants which responded with normal growth to 0.4 mmglycolaldehyde or 0.15 × 10−3mmpyridoxol was also found. The results suggest that a thiamine pyrophosphate-requiring step as well as glycolaldehyde may be involved in pyridoxal phosphate biosynthesis.
Catalytic Properties and Regulatory Diversity of Inorganic Pyrophosphatases from Photosynthetic Bacteria
Authors: Klemme Jobst-Heinrich , Klemme Brigitte , Gest Howard
Published: January 2020

Soluble inorganic pyrophosphatases of five species of nonsulfur purple bacteria were investigated in respect to reaction kinetics, regulatory behavior, and other characteristics. The enzymes appear to fall into two groups with correlated properties. The pyrophosphatases of
Rhodopseudomonas capsulata
and
R. spheroides
have molecular weights of ∼60,000, are stabilized by Co
2+
, and exhibit simple Michaelis-Menten reaction kinetics. On the other hand, the enzymes of
R. palustris, R. gelatinosa
, and
Rhodospirillum rubrum
are larger (molecular weight ∼100,000), require Zn
2+
for maintenance of catalytic activity, and show complex reaction kinetics; these pyrophosphatases are activated by free Mg
2+
ions and, in the absence of the latter, are inhibited by 2-phosphoglyceric acid. The results described indicate the existence of alternative control patterns for regulation of intracellular turnover of phosphate, which is in part mediated by pyrophosphatases.
Resistance to Penicillin in Mutants of a Penicillinase-Negative Organism,
Staphylococcus aureus
H
Authors: Park James T. , Griffith Mary E. , Stevenson Ian
Published: January 2020

Penicillin-resistant mutants of
Staphylococcus aureus
H were similar to the parent in their response to penicillin though proportionately more penicillin was required for a given effect. The mutants did not inactivate penicillin. Most of the penicillin-binding sites (presumed to be murein transpeptidase molecules) bound penicillin rapidly when exposed to a very low concentration of penicillin (0.1 μg/ml), and yet the mutants retained some functional murein transpeptidase even in the presence of 500 μg of penicillin per ml. An hypothesis based on (i) functional versus nonfunctional transpeptidase molecules and (ii) variations in accessibility to penicillin can explain these findings.
Evidence Suggestive of Compartmentalization of Deoxyribonucleic Acid-Synthesizing Systems in Freeze-Treated
Bacillus subtilis
Authors: Billen Daniel , Carreira Laura B. , Hadden Charles T. , Silverstein Saul J.
Published: January 2020

Freezing of
Bacillus subtilis
in liquid nitrogen results, upon thawing of the cells, in an enhanced deoxyribonucleoside triphosphate and reduced thymidine (Tdr) incorporation into cellular deoxyribonucleic acid (DNA). The DNA synthesized from thymidine triphosphate (TTP) was made by a “repair”-type system as determined by density transfer experiments. The mono- and diphosphate precursors were also incorporated by a “repair”-type synthesis. When Tdr was used as the radioactive precursor in the assay mixture, the product was only that expected from a semiconservative synthesis. Superlethal ultraviolet light exposure of the freeze-treated cells stimulated incorporation of phosphorylated precursors into DNA. Tdr uptake was greatly reduced by ultraviolet exposure, and only repair synthesis was observed. TTP and Tdr do not compete with one another in this system. The possibility that two DNA synthesizing systems exist in separate, non-mixing cellular compartments is considered.
Study of Adenine Aminohydrolase in the Yeast,
Schizosaccharomyces pombe
Authors: Abbondandolo Angelo , Weyer Anne , Heslot Henri , Lambert Micheline
Published: January 2020

Observation of the growth of some adenineless mutants of
Schizosaccharomyces pombe
on six substituted purine analogs leads to the hypothesis that an enzyme is present which catalyzes the conversion of these analogs into hypoxanthine. The enzyme adenase (adenine aminohydrolase, EC 3.5.4.2) has been found to be active in cell-free extracts of
S. pombe
. Results are reported which are in agreement with the hypothesis that this enzyme is responsible for the in vivo utilization of 6-chloropurine. This evidence comes mainly from a study of adenine aminohydrolase in two mutants selected for partial inability to grow on 6-chloropurine.
Novel Mutation Causing Derepression of Several Enzymes of Sulfur Metabolism in
Neurospora crassa
Authors: Burton Earl G. , Metzenberg Robert L.
Published: January 2020

A group of enzymes of sulfur metabolism (arylsulfatase, cholinesulfatase, and a number of others) are normally repressed in
Neurospora crassa
by an abundant supply of a “favored” sulfur source such as methionine or inorganic sulfate. A mutant called

scon
c

was isolated in which the formation of each of these enzymes is largely or completely nonrepressible. The structural genes for three of these enzymes have been mapped;

scon
c

is not linked to any of them. It is also not linked to
cys-3
, another gene which is involved in control of the same group of enzymes. Two alleles of the structural gene for arylsulfatase [
ars
+
and
ars
(
UFC-220
)] produce electrophoretically distinguishable forms of arylsulfatase. Heterokaryons with the constitution

scon
c
ars

+
+
scon
+
ars
(
UFC-220
) were prepared. These heterokaryons produce both forms of arylsulfatase under conditions of sulfur limitation, but produce only the wild-type (
ars
+
) form under conditions of sulfur abundance. When the alleles of
ars
and
scon
are in the opposite relationship, only the
ars
(
UFC-220
) form of arylsulfatase can be detected under conditions of sulfur abundance. Thus the effect of the

scon
c

mutation seems to be limited to its own nucleus. The implications of these findings are discussed.
Molecular Heterogeneity of the Bdellovibrios: Evidence of Two New Species
Authors: Seidler Ramon J. , Mandel M. , Baptist J. N.
Published: January 2020

A systematic examination of a variety of isolates of the bacterial endoparasite
Bdellovibrio
has revealed extensive molecular diversity. The quantity of deoxyribonucleic acid (DNA) polynucleotide homology ranges from more than 90% among the isolates with DNA containing 50 to 51% guanine plus cytosine (GC) to undetectable levels between the 43% GC and 51% GC isolates. The two isolates with low GC-containing DNA (H-I
Bdellovibrio
A3.12 and UKi2) have only 16% DNA homology. H-I
Bdellovibrio
A3.12 and 109 have barely detectable ribosomal ribonucleic acid (rRNA) homology, whereas the homology approaches 100% among all the high GC isolates tested. Cases of high DNA/DNA and DNA/rRNA homologies are reflected in low dissimilarities of enzyme migration patterns in starch gel electrophoresis. The dissimilarities exhibited among the high GC
Bdellovibrio
isolates are as low as those previously reported for different
Escherichia coli
strains. The zymograms of H-I
Bdellovibrio
A3.12 and UKi2 are completely different from each other as well as from all other bdellovibrios (100% dissimilarity). Genome sizes determined for the representative isolates demonstrate three size ranges which coincide with group differences based on the above measurements. Enzyme assays reveal that all isolates possess a tricarboxylic acid cycle and most contain an alanine and glutamic dehydrogenase. We conclude that the use of bacterial endoparasitism as a defining trait has resulted in a molecularly diverse collection of isolates. It is recommended that the specific epitaph
bacteriovorus
be used only for the type specimen (
Bdellovibrio
100 of Stolp and Starr, 1963) and for other related 50 to 51% GC isolates. The heterogeneity of the group warrants two new species. We designate
Bdellovibrio
A3.12 as the nomenclatural type of
B. starrii
sp. n. and
Bdellovibrio
UKi2 as the nomenclatural type of
B. stolpii
sp. n.