bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence that a New Antibiotic Flavone Glycoside Chemically Defends the Sea Grass
Thalassia testudinum
against Zoosporic Fungi
Authors: Jensen P. R. , Jenkins K. M. , Porter D. , Fenical W. 
Published: December 2019

ABSTRACT

Significantly fewer thraustochytrid protists (zoosporic fungi) were observed in association with healthy leaf tissue of the marine angiosperm
Thalassia testudinum
than in association with sterilized samples that were returned to the collection site for 48 h. In support of the hypothesis that sea grass secondary metabolites were responsible for these differences, extracts of healthy
T. testudinum
leaf tissues inhibited the growth of the co-occurring thraustochytrid
Schizochytrium aggregatum
and deterred the attachment of
S. aggregatum
motile zoospores to an extract-impregnated substrate. By using
S. aggregatum
for bioassay-guided chemical fractionation, a new flavone glycoside was isolated and structurally characterized as luteolin 7-
O
-β-
d
-glucopyranosyl-2"-sulfate. Whole-leaf tissue concentrations of this metabolite (4 mg/ml of wet leaf tissue) inhibited
S. aggregatum
attachment, and a significantly lower concentration (270 μg/ml) reduced thraustochytrid growth by 50%, suggesting that natural concentrations are at least 15 times greater than that needed for significant microbiological effects. These results offer the first complete chemical characterization of a sea grass sulfated flavone glycoside and provide evidence that a secondary metabolite chemically defends
T. testudinum
against fouling microorganisms.
Anaerobic Oxidation of [1,2-
14
C]Dichloroethene under Mn(IV)-Reducing Conditions
Authors: Bradley Paul M. , Landmeyer James E. , Dinicola Richard S. 
Published: December 2019

ABSTRACT

Anaerobic oxidation of [1,2-
14
C]dichloroethene to
14
CO
2
under Mn(IV)-reducing conditions was demonstrated. The results indicate that oxidative degradation of partially chlorinated solvents like dichloroethene can be significant even under anoxic conditions and demonstrate the potential importance of Mn(IV) reduction for remediation of chlorinated groundwater contaminants.
Mechanism of the Citrate Transporters in Carbohydrate and Citrate Cometabolism in
Lactococcus
and
Leuconostoc
Species
Authors: Bandell M. , Lhotte M. E. , Marty-Teysset C. , Veyrat A. , Prévost H. , Dartois V. , Diviès C. , Konings W. N. , Lolkema J. S. 
Published: December 2019

ABSTRACT

Citrate metabolism in the lactic acid bacterium
Leuconostoc mesenteroides
generates an electrochemical proton gradient across the membrane by a secondary mechanism (C. Marty-Teysset, C. Posthuma, J. S. Lolkema, P. Schmitt, C. Divies, and W. N. Konings, J. Bacteriol. 178:2178–2185, 1996). Reports on the energetics of citrate metabolism in the related organism
Lactococcus lactis
are contradictory, and this study was performed to clarify this issue. Cloning of the membrane potential-generating citrate transporter (CitP) of
Leuconostoc mesenteroides
revealed an amino acid sequence that is almost identical to the known sequence of the CitP of
Lactococcus lactis
. The cloned gene was expressed in a
Lactococcus lactis
Cit
−
strain, and the gene product was functionally characterized in membrane vesicles. Uptake of citrate was counteracted by the membrane potential, and the transporter efficiently catalyzed heterologous citrate-lactate exchange. These properties are essential for generation of a membrane potential under physiological conditions and show that the
Leuconostoc
CitP retains its properties when it is embedded in the cytoplasmic membrane of
Lactococcus lactis
. Furthermore, using the same criteria and experimental approach, we demonstrated that the endogenous CitP of
Lactococcus lactis
has the same properties, showing that the few differences in the amino acid sequences of the CitPs of members of the two genera do not result in different catalytic mechanisms. The results strongly suggest that the energetics of citrate degradation in
Lactococcus lactis
and
Leuconostoc mesenteroides
are the same; i.e., citrate metabolism in
Lactococcus lactis
is a proton motive force-generating process.
Identification and Analysis of Genes Involved in Anaerobic Toluene Metabolism by Strain T1: Putative Role of a Glycine Free Radical
Authors: Coschigano Peter W. , Wehrman Thomas S. , Young L. Y. 
Published: December 2019

ABSTRACT

The denitrifying strain T1 is able to grow with toluene serving as its sole carbon source. Two mutants which have defects in this toluene utilization pathway have been characterized. A clone has been isolated, and subclones which contain
tutD
and
tutE
, two genes in the T1 toluene metabolic pathway, have been generated. The
tutD
gene codes for an 864-amino-acid protein with a calculated molecular mass of 97,600 Da. The
tutE
gene codes for a 375-amino-acid protein with a calculated molecular mass of 41,300 Da. Two additional small open reading frames have been identified, but their role is not known. The TutE protein has homology to pyruvate formate-lyase activating enzymes. The TutD protein has homology to pyruvate formate-lyase enzymes, including a conserved cysteine residue at the active site and a conserved glycine residue that is activated to a free radical in this enzyme. Site-directed mutagenesis of these two conserved amino acids shows that they are also essential for the function of TutD.
Antibiotic Production by
Erwinia herbicola
Eh1087: Its Role in Inhibition of
Erwinia amylovora
and Partial Characterization of Antibiotic Biosynthesis Genes
Authors: Kearns L. P. , Mahanty H. K. 
Published: December 2019

ABSTRACT

Mutants of
Erwinia herbicola
Eh1087 (Ant
−
), which did not produce antibiotic activity against
Erwinia amylovora
, the fire blight pathogen, were selected after Tn
phoA
mutagenesis. In immature pear fruit Ant
−
mutants grew at the same rate as wild-type strain Eh1087 but did not suppress development of the disease caused by
E. amylovora
. These results indicated that antibiosis plays an important role in the suppression of disease by strain Eh1087. All of the Ant
−
mutations obtained were located in a 2.2-kb region on a 200-kb indigenous plasmid. Sequence analysis of the mutated DNA region resulted in identification of six open reading frames, designated ORF1 through ORF6, four of which were essential to antibiotic expression. One gene was identified as a gene which encodes a translocase protein which is probably involved in antibiotic secretion. A sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of plasmid proteins produced in
Escherichia coli
minicells confirmed the presence of proteins whose sizes corresponded to the sizes of the predicted open reading frame products.
New
Bradyrhizobium japonicum
Strains That Possess High Copy Numbers of the Repeated Sequence RSα
Authors: Minamisawa Kiwamu , Isawa Tsuyoshi , Nakatsuka Yoko , Ichikawa Norikazu 
Published: December 2019

ABSTRACT

In a survey of DNA fingerprints of indigenous
Bradyrhizobium japonicum
with the species-specific repeated sequences RSα and RSβ, 21 isolates from three field sites showed numerous RS-specific hybridization bands. The isolates were designated highly reiterated sequence-possessing (HRS) isolates, and their DNA hybridization profiles were easily distinguished from the normal patterns. Some HRS isolates from two field sites possessed extremely high numbers of RSα copies, ranging from 86 to 175 (average, 128), and showed shifts and duplications of
nif
- and
hup
-specific hybridization bands. The HRS isolates exhibited slower growth than normal isolates, although no difference in symbiotic properties was detected between the HRS and normal isolates. Nucleotide sequence analysis of 16S rRNA genes showed that HRS isolates were strains of
B. japonicum
. There was no difference in the spectra of serological and hydrogenase groupings of normal and HRS isolates. Some HRS isolates possessed a tandem repeat RSα dimer that is similar to the structure of (IS
30
)
2
, which was shown to cause a burst of transpositional rearrangements in
Escherichia coli
. The results suggest that HRS isolates are derived from normal isolates in individual fields by genome rearrangements that may be mediated by insertion sequences such as RSα.
Improved Dechlorinating Performance of Upflow Anaerobic Sludge Blanket Reactors by Incorporation of
Dehalospirillum multivorans
into Granular Sludge
Authors: Hörber Christine , Christiansen Nina , Arvin Erik , Ahring Birgitte K. 
Published: December 2019

ABSTRACT

Dechlorination of tetrachloroethene, also known as perchloroethylene (PCE), was investigated in an upflow anaerobic sludge blanket (UASB) reactor after incorporation of the strictly anaerobic, reductively dechlorinating bacterium
Dehalospirillum multivorans
into granular sludge. This reactor was compared to the reference 1 (R1) reactor, where the granules were autoclaved to remove all dechlorinating abilities before inoculation, and to the reference 2 (R2) reactor, containing only living granular sludge. All three reactors were fed mineral medium containing 3 to 57 μM PCE, 2 mM formate, and 0.5 mM acetate and were operated under sterile conditions. In the test reactor, an average of 93% (mole/mole) of the effluent chloroethenes was dichloroethene (DCE), compared to 99% (mole/mole) in the R1 reactor. The R2 reactor, with no inoculation, produced only trichloroethene (TCE), averaging 43% (mole/mole) of the effluent chloroethenes. No dechlorination of PCE was observed in an abiotic control consisting of sterile granules without inoculum. During continuous operation with stepwise-reduced hydraulic retention times (HRTs), both the test reactor and the R1 reactor showed conversion of PCE to DCE, even at HRTs much lower than the reciprocal maximum specific growth rate of
D. multivorans
, indicating that this bacterium was immobilized in the living and autoclaved granular sludge. In contrast, the R2 reactor, with no inoculation of
D. multivorans
, only converted PCE to TCE under the same conditions. Immobilization could be confirmed by using fluorescein-labeled antibody probes raised against
D. multivorans
. In granules obtained from the R1 reactor,
D. multivorans
grew mainly in microcolonies located in the centers of the granules, while in the test reactor, the bacterium mainly covered the surfaces of granules.
arfI
and
arfII
, Two Genes Encoding α-
l
-Arabinofuranosidases in
Cytophaga xylanolytica
Authors: Kim Kwi S. , Lilburn Timothy G. , Renner Michael J. , Breznak John A. 
Published: December 2019

ABSTRACT

arfI
encoded the 57.7-kDa subunit of
Cytophaga xylanolytica
arabinofuranosidase I (ArfI).
arfII
encoded a 59.2-kDa subunit of ArfII. Products of both cloned genes liberated arabinose from arabinan and arabinoxylan. The deduced amino acid sequences of ArfI and ArfII revealed numerous regions that were identical to each other and to regions of homologous proteins from
Bacteroides ovatus
,
Bacillus subtilis
, and
Clostridium stercorarium.
Cloning of the Ribosomal Protein L41 Gene of
Phaffia rhodozyma
and Its Use as a Drug Resistance Marker for Transformation
Authors: Kim I.-G. , Nam S.-K. , Sohn J.-H. , Rhee S.-K. , An G.-H. , Lee S.-H. , Choi E.-S. 
Published: December 2019

ABSTRACT

The ribosomal protein L41 gene of
Phaffia rhodozyma
was cloned and used as a dominant selectable marker for cycloheximide resistance in the transformation of
P. rhodozyma
. Electrotransformation with a plasmid containing a ribosomal DNA fragment as a targeting signal typically yielded 800 to 1,200 transformants/μg of DNA with an integrated copy number of about seven per haploid genome.
Differentiation of
Cryptosporidium parvum
Isolates by a Simplified Randomly Amplified Polymorphic DNA Technique
Authors: Deng Ming Qi , Cliver Dean O. 
Published: December 2019

ABSTRACT

Genomic DNA was isolated from
Cryptosporidium parvum
oocysts by a specific immunomagnetic separation-in vitro excystation procedure and subjected to randomly amplified polymorphic DNA analysis using sequence-independent primers. An estuary
C. parvum
isolate was easily differentiated from several bovine isolates, while five bovine isolates of the same origin were indistinguishable from each other.
Small, Acid-Soluble Spore Proteins of the α/β Type Do Not Protect the DNA in
Bacillus subtilis
Spores against Base Alkylation
Authors: Setlow Barbara , Tautvydas Kes J. , Setlow Peter 
Published: December 2019

ABSTRACT

Ethyl methanesulfonate (EMS) killed wild-type
Bacillus subtilis
spores as rapidly as spores lacking small, acid-soluble proteins (SASP) of the α/β type (α
−
β
−
spores), and 20% of the survivors had obvious mutations. A
recA
mutation increased the EMS sensitivity of wild-type and α
−
β
−
spores similarly but reduced their mutagenesis; EMS treatment of dormant spores also resulted in the induction of RecA synthesis during spore germination. EMS generated similar levels of alkylated bases in wild-type and α
−
β
−
spore DNAs, in purified DNA, or in DNA saturated with α/β-type SASP. Ethylene oxide (EtO) also generated similar levels of base alkylation in wild-type and α
−
β
−
spore DNAs. These data indicate that EMS and EtO kill spores at least in part by DNA damage but that α/β-type SASP, which protect DNA against many types of damage, do not protect spore DNA from base alkylation.
Regulation of Lipid Synthesis in
Bradyrhizobium japonicum
: Low Oxygen Concentrations Trigger Phosphatidylinositol Biosynthesis
Authors: Tang Yin , Hollingsworth Rawle I. 
Published: December 2019

ABSTRACT

Lowering oxygen tension in free-living
Bradyrhizobium japonicum
resulted in a dramatic switch of membrane chemistry in which phosphatidylcholine, the predominant lipid in aerated cultures, was no longer synthesized and phosphatidylethanolamine became the major lipid. Besides this change, phosphatidylinositol, a typical plant lipid rarely found in bacteria, was also synthesized.
Endopolygalacturonase PG1 in Different Formae Speciales of
Fusarium oxysporum
Authors: Di Pietro Antonio , García-Maceira Fe I. , Huertas-González M. Dolores , Ruíz-Roldan M. Carmen , Caracuel Zaira , Barbieri Andrea S. , Roncero M. Isabel G. 
Published: December 2019

ABSTRACT

PG1, the major endopolygalacturonase of the vascular wilt pathogen
Fusarium oxysporum
, was secreted during growth on pectin by 10 of 12 isolates belonging to seven formae speciales, as determined with isoelectric focusing zymograms and sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels. A Southern analysis of genomic DNA and PCR performed with gene-specific primers revealed that the
pg1
locus was highly conserved structurally in most isolates. Two PG1-deficient isolates were identified; one lacked the encoding gene, and the other carried a
pg1
allele disrupted by a 3.2-kb insertion with sequence homology to
hAT
transposases. The virulence for muskmelon of different
F. oxysporum
f. sp.
melonis
isolates was not correlated with PG1 production in vitro. We concluded that PG1 is widely distributed in
F. oxysporum
and that it is not essential for pathogenicity.
Bsn-t
Alleles from French Field Strains of
Agaricus bisporus
Authors: Callac Philippe , Hocquart Sophie , Imbernon Micheline , Desmerger Christophe , Olivier Jean-Marc 
Published: December 2019

ABSTRACT

In the
Agaricus bisporus
desert population in California, the dominant
Bsn-t
allele determines the production of tetrasporic basidia and homokaryotic spores (
n
) that characterize a heterothallic life cycle. Strains belonging to a French population have the
Bsn-b/b
genotype that results in bisporic basidia that produce heterokaryotic spores (
n + n
) which characterize a pseudohomothallic life cycle. More recombination occurs in the tetrasporic population than in the bisporic population. In France, tetrasporic strains are rare. For two such isolates, Bs 261 and Bs 423, we determined the life cycle, the heritability of the tetrasporic trait, the amount of variation in the recombination rate, and the haploid fruiting ability. We found that (i) Bs 261 was heterothallic, (ii) Bs 423 was homokaryotic and homothallic, (iii) Bs 261 was
Bsn-t/b
, (iv) recombination on a segment of chromosome
I
depended on the genotype at
BSN
, (v) some of the homokaryotic offspring of Bs 261 and all of the progeny of Bs 423 were able to fruit, (vi) Bs 261 and Bs 423 were closely related, and (vii) Bs 423 was partially intersterile with other strains of the species.
Enzymological Characteristics of the Hyperthermostable NAD-Dependent Glutamate Dehydrogenase from the Archaeon
Pyrobaculum islandicum
and Effects of Denaturants and Organic Solvents
Authors: Kujo Chizu , Ohshima Toshihisa 
Published: December 2019

ABSTRACT

NAD-dependent glutamate dehydrogenase (
l
-glutamate:NAD oxidoreductase, deaminating; EC
1.4.1.2
) was purified to homogeneity from a crude extract of the continental hyperthermophilic archaeon
Pyrobaculum islandicum
by two successive Red Sepharose CL-4B affinity chromatographies. The enzyme is the most thermostable NAD-dependent dehydrogenase found to date; the activity was not lost after incubation at 100°C for 2 h. The enzyme activity increased linearly with temperature, and the maximum was observed at ca. 90°C. The enzyme has a molecular mass of about 220 kDa and consists of six subunits with identical molecular masses of 36 kDa. The enzyme required NAD as a coenzyme for
l
-glutamate deamination and was different from the NADP-dependent glutamate dehydrogenase from other hyperthermophiles. The

K
m

values for NAD,
l
-glutamate, NADH, 2-oxoglutarate, and ammonia were 0.025, 0.17, 0.0050, 0.066, and 9.7 mM, respectively. The enzyme activity was significantly increased by the addition of denaturants such as guanidine hydrochloride and some water-miscible organic solvents such as acetonitrile and tetrahydrofuran. When fluorescence of the enzyme was measured in the presence of guanidine hydrochloride, a significant emission spectrum change and a shift in the maximum were observed but not in the presence of urea. These results indicate that this hyperthermophilic enzyme may have great potential in applications to biosensor and bioreactor processes.
Structure of a Microbial Community in Soil after Prolonged Addition of Low Levels of Simulated Acid Rain
Authors: Pennanen Taina , Fritze Hannu , Vanhala Pekka , Kiikkilä Oili , Neuvonen Seppo , Bååth Erland 
Published: December 2019

ABSTRACT

Humus samples were collected 12 growing seasons after the start of a simulated acid rain experiment situated in the subarctic environment. The acid rain was simulated with H
2
SO
4
, a combination of H
2
SO
4
and HNO
3
, and HNO
3
at two levels of moderate acidic loads close to the natural anthropogenic pollution levels of southern Scandinavia. The higher levels of acid applications resulted in acidification, as defined by humus chemistry. The concentrations of base cations decreased, while the concentrations of exchangeable H
+
, Al, and Fe increased. Humus pH decreased from 3.83 to 3.65. Basal respiration decreased with decreasing humus pH, and total microbial biomass, measured by substrate-induced respiration and total amount of phospholipid fatty acids (PLFA), decreased slightly. An altered PLFA pattern indicated a change in the microbial community structure at the higher levels of acid applications. In general, branched fatty acids, typical of gram-positive bacteria, increased in the acid plots. PLFA analysis performed on the bacterial community growing on agar plates also showed that the relative amount of PLFA specific for gram-positive bacteria increased due to the acidification. The changed bacterial community was adapted to the more acidic environment in the acid-treated plots, even though bacterial growth rates, estimated by thymidine and leucine incorporation, decreased with pH. Fungal activity (measured as acetate incorporation into ergosterol) was not affected. This result indicates that bacteria were more affected than fungi by the acidification. The capacity of the bacterial community to utilize 95 different carbon sources was variable and only showed weak correlations to pH. Differences in the toxicities of H
2
SO
4
and HNO
3
for the microbial community were not found.
Rapid and Reliable Identification of Food-Borne Yeasts by Fourier-Transform Infrared Spectroscopy
Authors: Kümmerle Michael , Scherer Siegfried , Seiler Herbert 
Published: December 2019

ABSTRACT
Computer-based Fourier-transform infrared spectroscopy (FT-IR) was used to identify food-borne, predominantly fermentative yeasts. Dried yeast suspensions provided the films suitable for FT-IR measurement. Informative windows in the spectrum were selected and combined to achieve optimal results. A reference spectrum library was assembled, based on 332 defined yeast strains from international yeast collections and our own isolates. All strains were identified with conventional methods using physiological and morphological characteristics. In order to assess identification quality, another 722 unknown yeast isolates not included in the reference spectrum library were identified both by classical methods and by comparison of their FT-IR spectra with those of the reference spectrum library. Ninety-seven and one-half percent of these isolates were identified correctly by FT-IR. Easy handling, rapid identification within 24 h when starting from a single colony, and a high differentiation capacity thus render FT-IR technology clearly superior to other routine methods for the identification of yeasts.
Isolation and Characterization of a Dibenzofuran-Degrading Yeast: Identification of Oxidation and Ring Cleavage Products
Authors: Hammer Elke , Krowas Dirk , Schäfer Annett , Specht Michael , Francke Wittko , Schauer Frieder 
Published: December 2019

ABSTRACT

We characterized the ability of a yeast to cleave the aromatic structure of the dioxin-like compound dibenzofuran. The yeast strain was isolated from a dioxin-contaminated soil sample and identified as
Trichosporon mucoides
. During incubation of glucose-pregrown cells with dibenzofuran, six major metabolites were detected by high-performance liquid chromatography. The formation of four different monohydroxylated dibenzofurans was proven by comparison of analytical data (gas chromatography-mass spectrometry) with that for authentic standards. Further oxidation produced 2,3-dihydroxydibenzofuran and its ring cleavage product 2-(1-carboxy methylidene)-2,3-dihydrobenzo[
b
]furanylidene glycolic acid, which were characterized by mass spectrometry and
1
H nuclear magnetic resonance spectroscopy. These two metabolites are derived from 2-hydroxydibenzofuran and 3-hydroxydibenzofuran, as shown by incubation experiments using these monohydroxylated dibenzofurans as substrates.
Myoglobin as an Inhibitor of Exopeptidases from
Lactobacillus sake
Authors: Sanz Yolanda , Toldrá Fidel 
Published: December 2019

ABSTRACT

The effects of myoglobin on exopeptidases of
Lactobacillus sake
were determined. Inhibition of the aminopeptidases increased as the myoglobin concentration increased; aminopeptidase 3 was the most affected (90% inhibition). Aminopeptidases 1, 2, and 4 showed similar inhibition levels (around 60%). Myoglobin did not affect tripeptidase activity. Thus, myoglobin could limit amino acid generation in meat systems.
Isolation of a Bacterial Strain with the Ability To Utilize the Sulfonated Azo Compound 4-Carboxy-4′-Sulfoazobenzene as the Sole Source of Carbon and Energy
Authors: Blümel Silke , Contzen Matthias , Lutz Martina , Stolz Andreas , Knackmuss Hans-Joachim 
Published: December 2019

ABSTRACT

A bacterial strain (strain S5) which grows aerobically with the sulfonated azo compound 4-carboxy-4′-sulfoazobenzene as the sole source of carbon and energy was isolated. This strain was obtained by continuous adaptation of “
Hydrogenophaga palleronii
” S1, which has the ability to grow aerobically with 4-aminobenzenesulfonate. Strain S5 probably cleaves 4-carboxy-4′-sulfoazobenzene reductively under aerobic conditions to 4-aminobenzoate and 4-aminobenzene-sulfonate, which are mineralized by previously established degradation pathways.