bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetics of Vegetative Incompatibility in
Cryphonectria parasitica
Authors: Cortesi Paolo , Milgroom Michael G. 
Published: December 2019

ABSTRACT

Vegetative incompatibility in the chestnut blight fungus,
Cryphonectria parasitica
, in Europe is controlled by six unlinked
vic
loci, each with two alleles. Four previously identified
vic
loci (
vic1
,
vic2
,
vic3
, and
vic4
) were polymorphic in European vegetative compatibility (vc) types. Two new loci,
vic6
and
vic7
, also were identified among European vc types. In one cross,
vic
genes segregated independently at five loci, and 194 progeny were assigned to 32 vc types; none of these loci were linked. A total of 64 vc types were identified from all crosses. All 64 genotypes possible from six
vic
loci, each with two alleles (2
6
= 64), were identified and assigned to vc types. Based on our model, vc types v-c 5 and v-c 10, which had been used in previous genetic studies, differ by only five
vic
genes. Future studies of vc types in
C. parasitica
can use knowledge of
vic
genotypes for analysis of population genetic structure based on
vic
allele frequencies and to determine the effect of each
vic
gene on virus transmission between vc types.
Oxidation of Trichloroethylene, 1,1-Dichloroethylene, and Chloroform by Toluene/
o
-Xylene Monooxygenase from
Pseudomonas stutzeri
OX1
Authors: Chauhan Sadhana , Barbieri Paola , Wood Thomas K. 
Published: December 2019

ABSTRACT

Toluene/
o
-xylene monooxygenase (ToMO) from
Pseudomonas stutzeri
OX1, which oxidizes toluene and
o
-xylene, was examined for its ability to degrade the environmental pollutants trichloroethylene (TCE), 1,1-dichloroethylene (1,1-DCE),
cis
-1,2-DCE,
trans
-1,2-DCE, chloroform, dichloromethane, phenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, 2,3,5,6-tetrachlorophenol, and 2,3,4,5,6-pentachlorophenol.
Escherichia coli
JM109 that expressed ToMO from genes on plasmid pBZ1260 under control of the
lac
promoter degraded TCE (3.3 μM), 1,1-DCE (1.25 μM), and chloroform (6.3 μM) at initial rates of 3.1, 3.6, and 1.6 nmol/(min · mg of protein), respectively. Stoichiometric amounts of chloride release were seen, indicating mineralization (2.6, 1.5, and 2.3 Cl
−
atoms per molecule of TCE, 1,1-DCE, and chloroform, respectively). Thus, the substrate range of ToMO is extended to include aliphatic chlorinated compounds.
Fungal Biotransformation of 6-Nitrochrysene
Authors: Pothuluri Jairaj V. , Sutherland John B. , Freeman James P. , Cerniglia Carl E. 
Published: December 2019

ABSTRACT

The fungus
Cunninghamella elegans
was used to biotransform 6-nitrochrysene, a mutagen that is a widespread environmental contaminant. After 6 days, 74% of the
3
H-labeled 6-nitrochrysene added had been metabolized to two isomeric sulfate conjugates. These conjugates were separated by high-performance liquid chromatography and identified by UV-visible,
1
H nuclear magnetic resonance, and mass spectral techniques as 6-nitrochrysene 1-sulfate and 6-nitrochrysene 2-sulfate.
Effect of Humic Fractions and Clay on Biodegradation of Phenanthrene by a
Pseudomonas fluorescens
Strain Isolated from Soil
Authors: Ortega-Calvo Jose-Julio , Saiz-Jimenez Cesareo 
Published: December 2019

ABSTRACT

The mineralization of phenanthrene in pure cultures of a
Pseudomonas fluorescens
strain, isolated from soil, was measured in the presence of soil humic fractions and montmorillonite. Humic acid and clay, either separately or in combination, shortened the acclimation phase. A higher mineralization rate was measured in treatments with humic acid at 100 μg/ml. Humic acid at 10 μg/ml stimulated the transformation only in the presence of 10 g of clay per liter. We suggest that sorption of phenanthrene to these soil components may result in a higher concentration of substrate in the vicinity of the bacterial cells and therefore may increase its bioavailability.
Signal Transduction in the Protozoan Host
Hartmannella vermiformis
upon Attachment and Invasion by
Legionella micdadei
Authors: Abu Kwaik Yousef , Venkataraman Chandrasekar , Harb Omar S. , Gao Liang-Yong 
Published: December 2019

ABSTRACT

The intracellular pathogens
Legionella micdadei
and
Legionella pneumophila
are the two most common
Legionella
species that cause Legionnaires’ disease. Intracellular replication within pulmonary cells is the hallmark of Legionnaires’ disease. In the environment, legionellae are parasites of protozoans, and intracellular bacterial replication within protozoans plays a major role in the transmission of Legionnaires’ disease. In this study, we characterized the initial host signal transduction mechanisms involved during attachment to and invasion of the protozoan host
Hartmannella vermiformis
by
L. micdadei
. Bacterial attachment prior to invasion of
H. vermiformis
by
L. micdadei
is associated with tyrosine dephosphorylation of multiple host cell proteins, including a 170-kDa protein. We have previously shown that this 170-kDa protein is the galactose
N
-acetylgalactosamine (Gal/GalNAc)-inhibitable lectin receptor that mediates attachment to and invasion of
H. vermiformis
by
L. pneumophila
. Subsequent bacterial entry targets
L. micdadei
into a phagosome that is not surrounded by the rough endoplasmic reticulum (RER). In contrast, uptake of
L. pneumophila
mediated by attachment to the Gal/GalNAc lectin is followed by targeting of the bacterium into an RER-surrounded phagosome. These results indicate that despite similarities in the
L. micdadei
and
L. pneumophila
attachment-mediated signal transduction mechanisms in
H. vermiformis
, the two bacterial species are targeted into morphologically distinct phagosomes in their natural protozoan host.
Cloning, Nucleotide Sequence, and Expression in
Escherichia coli
of Levansucrase Genes from the Plant Pathogens
Pseudomonas syringae
pv. glycinea and
P. syringae
pv. phaseolicola
Authors: Hettwer Ursula , Jaeckel Frank R. , Boch Jens , Meyer Manfred , Rudolph Klaus , Ullrich Matthias S. 
Published: December 2019

ABSTRACT

Plant-pathogenic bacteria produce various extracellular polysaccharides (EPSs) which may function as virulence factors in diseases caused by these bacteria. The EPS levan is synthesized by the extracellular enzyme levansucrase in
Pseudomonas syringae
,
Erwinia amylovora
, and other bacterial species. The
lsc
genes encoding levansucrase from
P. syringae
pv. glycinea PG4180 and
P. syringae
pv. phaseolicola NCPPB 1321 were cloned, and their nucleotide sequences were determined. Heterologous expression of the
lsc
gene in
Escherichia coli
was found in four and two genomic library clones of strains PG4180 and NCPPB 1321, respectively. A 3.0-kb
Pst
I fragment common to all six clones conferred levan synthesis on
E. coli
when further subcloned. Nucleotide sequence analysis revealed a 1,248-bp open reading frame (ORF) derived from PG4180 and a 1,296-bp ORF derived from NCPPB 1321, which were both designated
lsc
. Both ORFs showed high homology to the
E. amylovora
and
Zymomonas mobilis lsc
genes at the nucleic acid and deduced amino acid sequence levels. Levansucrase was not secreted into the supernatant but was located in the periplasmic fraction of
E. coli
harboring the
lsc
gene. Expression of
lsc
was found to be dependent on the vector-based P

lac

promoter, indicating that the native promoter of
lsc
was not functional in
E. coli
. Insertion of an antibiotic resistance cassette in the
lsc
gene abolished levan synthesis in
E. coli
. A PCR screening with primers derived from
lsc
of
P. syringae
pv. glycinea PG4180 allowed the detection of this gene in a number of related bacteria.
Characterization of the Bactericidal Effects of Sodium Nitroprusside and Other Pentacyanonitrosyl Complexes on the Food Spoilage BacteriumClostridium sporogenes
Authors: Joannou Christopher L. , Cui Xiao-Yuan , Rogers Nicola , Vielotte Natasha , Torres Martinez Claudia L. , Vugman Ney V. , Hughes Martin N. , Cammack Richard 
Published: December 2019

ABSTRACTThe potent bactericidal activity of sodium nitroprusside {SNP; Na2[Fe(CN)5(NO)]} towardsClostridium sporogeneshas been investigated. SNP inhibited cell growth in the concentration range of 10 to 40 μM. Concentrations above 80 μM caused irreversible loss of cell viability and cell lysis. Inhibition of cell growth was similar in complex and in defined media. SNP was found to be unreactive towards individual components of the defined medium, with the exception of cysteine. The chemical characteristics responsible for the potency of SNP were investigated by synthesizing analogs of SNP in which the Fe was replaced by different metals. The inhibitory potency of the pentacyanonitrosyl complexes decreased in the order Fe > Cr > V, which correlates with N-O stretching frequency (vNO). In contrast, the Ru complex which had avNO comparable to that of Fe was a poor inhibitor. Electron paramagnetic resonance spectroscopy showed that SNP was rapidly reduced to the paramagnetic Fe(I) compound [Fe(CN)4(NO)]2−on contact with cells. Analysis of fractions from SNP-treated cells showed 90% oxidation of thiols in the cell walls compared with those in control cells. The toxicity of SNP involves S-nitrosation and reduction, the lack of toxicity of the Ru analog being consistent with the fact that it has poor reactivity towards thiols. WhenC. sporogenescells were exposed to sublethal concentrations of SNP and viewed under the electron microscope, they showed blisters on the surface. These results point to the cell wall surface as a primary point of attack of the nitrosyl complex.
Contribution of Indole-3-Acetic Acid Production to the Epiphytic Fitness of
Erwinia herbicola
Authors: Brandl M. T. , Lindow S. E. 
Published: December 2019

ABSTRACT

Erwinia herbicola
299R produces large quantities of indole-3-acetic acid (IAA) in culture media supplemented with
l
-tryptophan. To assess the contribution of IAA production to epiphytic fitness, the population dynamics of the wild-type strain and an IAA-deficient mutant of this strain on leaves were studied. Strain 299XYLE, an isogenic IAA-deficient mutant of strain 299R, was constructed by insertional interruption of the indolepyruvate decarboxylase gene of strain 299R with the
xylE
gene, which encodes a 2,3-catechol dioxygenase from
Pseudomonas putida
mt-2. The
xylE
gene provided a useful marker for monitoring populations of the IAA-deficient mutant strain in mixed populations with the parental strain in ecological studies. A root bioassay for IAA, in which strain 299XYLE inhibited significantly less root elongation than strain 299R, provided evidence that
E. herbicola
produces IAA on plant surfaces in amounts sufficient to affect the physiology of its host and that IAA production in strain 299R is not solely an in vitro phenomenon. The epiphytic fitness of strains 299R and 299XYLE was evaluated in greenhouse and field studies by analysis of changes in the ratio of the population sizes of these two strains after inoculation as mixtures onto plants. Populations of the parental strain increased to approximately twice those of the IAA-deficient mutant strain after coinoculation in a proportion of 1:1 onto bean plants in the greenhouse and onto pear flowers in field studies. In all experiments, the ratio of the population sizes of strain 299R and 299XYLE increased during periods of active growth on plant tissue but not when population sizes were not increasing with time.
Conversion of Methionine to Thiols by Lactococci, Lactobacilli, and Brevibacteria
Authors: Dias Benjamin , Weimer Bart 
Published: December 2019

ABSTRACT

Methanethiol has been strongly associated with desirable Cheddar cheese flavor and can be formed from the degradation of methionine (Met) via a number of microbial enzymes. Methionine γ-lyase is thought to play a major role in the catabolism of Met and generation of methanethiol in several species of bacteria. Other enzymes that have been reported to be capable of producing methanethiol from Met in lactic acid bacteria include cystathionine β-lyase and cystathionine γ-lyase. The objective of this study was to determine the production, stability, and activities of the enzymes involved in methanethiol generation in bacteria associated with cheese making. Lactococci and lactobacilli were observed to contain high levels of enzymes that acted primarily on cystathionine. Enzyme activity was dependent on the concentration of sulfur amino acids in the growth medium. Met aminotransferase activity was detected in all of the lactic acid bacteria tested and α-ketoglutarate was used as the amino group acceptor. In
Lactococcus lactis
subsp.
cremoris
S2, Met aminotransferase was repressed with increasing concentrations of Met in the growth medium. While no Met aminotransferase activity was detected in
Brevibacterium linens
BL2, it possessed high levels of
l
-methionine γ-lyase that was induced by addition of Met to the growth medium. Met demethiolation activity at pH 5.2 with 4% NaCl was not detected in cell extracts but was detected in whole cells. These data suggest that Met degradation in Cheddar cheese will depend on the organism used in production, the amount of enzyme released during aging, and the amount of Met in the matrix.
Purification and Characterization of Three Thermostable Endochitinases of a Noble
Bacillus
Strain, MH-1, Isolated from Chitin-Containing Compost
Authors: Sakai Kenji , Yokota Akira , Kurokawa Hajime , Wakayama Mamoru , Moriguchi Mitsuaki 
Published: December 2019

ABSTRACT

A thermophilic and actinic bacterium strain, MH-1, which produced three different endochitinases in its culture fluid was isolated from chitin-containing compost. The microorganism did not grow in any of the usual media for actinomyces but only in colloidal chitin supplemented with yeast extract and (2,6-
O
-dimethyl)-β-cyclodextrin. Compost extract enhanced its growth. In spite of the formation of branched mycelia, other properties of the strain, such as the formation of endospores, the presence of meso-diaminopimelic acid in the cell wall, the percent G+C of DNA (55%), and the partial 16S ribosomal DNA sequence, indicated that strain MH-1 should belong to the genus
Bacillus
. Three isoforms of endochitinase (L, M, and S) were purified to homogeneity and characterized from
Bacillus
sp. strain MH-1. They had different molecular masses (71, 62, and 53 kDa), pIs (5.3, 4.8, and 4.7), and N-terminal amino acid sequences. Chitinases L, M, and S showed relatively high temperature optima (75, 65, and 75°C) and stabilities and showed pH optima in an acidic range (pH 6.5, 5.5, and 5.5, respectively). When reacted with acetylchitohexaose [(GlcNAc)
6
], chitinases L and S produced (GlcNAc)
2
at the highest rate while chitinase M produced (GlcNAc)
3
at the highest rate. None of the three chitinases hydrolyzed (GlcNAc)
2
. Chitinase L produced (GlcNAc)
2
and (GlcNAc)
3
in most abundance from 66 and 11% partially acetylated chitosan. The
p
-nitrophenol (pNP)-releasing activity of chitinase L was highest toward pNP-(GlcNAc)
2
, and those of chitinases M and S were highest toward pNP-(GlcNAc)
3
. All three enzymes were inert to pNP-GlcNAc. AgCl, HgCl
2
, and (GlcNAc)
2
inhibited the activities of all three enzymes, while MnCl
2
and CaCl
2
slightly activated all of the enzymes.
Effect of Nitrogen Source on Growth and Trichloroethylene Degradation by Methane-Oxidizing Bacteria
Authors: Chu Kung-Hui , Alvarez-Cohen Lisa 
Published: December 2019

ABSTRACT

The effect of nitrogen source on methane-oxidizing bacteria with respect to cellular growth and trichloroethylene (TCE) degradation ability were examined. One mixed chemostat culture and two pure type II methane-oxidizing strains,
Methylosinus trichosporium
OB3b and strain CAC-2, which was isolated from the chemostat culture, were used in this study. All cultures were able to grow with each of three different nitrogen sources: ammonia, nitrate, and molecular nitrogen. Both
M. trichosporium
OB3b and strain CAC-2 showed slightly lower net cellular growth rates and cell yields but exhibited higher methane uptake rates, levels of poly-β-hydroxybutyrate (PHB) production, and naphthalene oxidation rates when grown under nitrogen-fixing conditions. The TCE-degrading ability of each culture was measured in terms of initial TCE oxidation rates and TCE transformation capacities (mass of TCE degraded/biomass inactivated), measured both with and without external energy sources. Higher initial TCE oxidation rates and TCE transformation capacities were observed in nitrogen-fixing mixed,
M. trichosporium
OB3b, and CAC-2 cultures than in nitrate- or ammonia-supplied cells. TCE transformation capacities were found to correlate with cellular PHB content in all three cultures. The results of this study suggest that the nitrogen-fixing capabilities of methane-oxidizing bacteria can be used to select for high-activity TCE degraders for the enhancement of bioremediation in fixed-nitrogen-limited environments.
Cellular Events Involved in Survival of Individual Arbuscular Mycorrhizal Symbionts Growing in the Absence of the Host
Authors: Logi Cable , Sbrana Cristiana , Giovannetti Manuela 
Published: December 2019

ABSTRACT

A survival strategy operating in the absence of the host was shown in obligately biotrophic arbuscular mycorrhizal (AM) symbionts. When no host-derived signals from the surrounding environment were perceived by germinating spores, fungal hyphae underwent a programmed growth arrest and resource reallocation, allowing long-term maintenance of viability and host infection capability. The early stages of mycelial growth of AM fungi were studied by a combination of time-lapse and video-enhanced light microscopy, image analysis, and immunodetection, with the aim of acquiring knowledge of cell events leading to the arrest of mycelial growth. The time-course of growth arrest was resolved by precisely timing the growth rate and magnitude of the mycelium originating from individual spores of
Glomus caledonium
. Extensive mycelial growth was observed during the first 15 days; thereafter, fungal hyphae showed retraction of protoplasm from the tips, with formation of retraction septa separating viable from empty hyphal segments. This active process involved migration of nuclei and cellular organelles and appeared to be functional in the ability of the fungus to survive in the absence of a host. Immunodetection of cytoskeletal proteins, metabolic activity, and the retention of infectivity of germinated spores confirmed the developmental data. The highest amounts of tubulins were detected when hyphal growth had ceased but when retraction of protoplasm was most active. This was consistent with the role of the cytoskeleton during protoplasm retraction. Succinate dehydrogenase activity in hyphae proximal to the mother spore was still detectable in 6-month-old mycelium, which remained viable and able to form appressoria and produce symbiotic structures.
Composition and Susceptibility to Chlorhexidine of Multispecies Biofilms of Oral Bacteria
Authors: Pratten J. , Barnett P. , Wilson M. 
Published: December 2019

ABSTRACT
Using a constant-depth film fermentor, we have grown a six-membered biofilm community with a bacterial composition similar to that found in supragingival dental plaque. Cryosectioning revealed the distribution of bacteria throughout the biofilm. Exposure to 0.2% chlorhexidine for up to 5 min had little effect on biofilm viability.
Diversity of
Frankia
Strains in Root Nodules of Plants from the Families Elaeagnaceae and Rhamnaceae
Authors: Clawson Michael L. , Carú Margarita , Benson David R. 
Published: December 2019

ABSTRACT

Partial 16S ribosomal DNAs (rDNAs) were PCR amplified and sequenced from
Frankia
strains living in root nodules of plants belonging to the families Elaeagnaceae and Rhamnaceae, including
Colletia hystrix
,
Elaeagnus angustifolia
, an unidentified
Elaeagnus
sp.,
Talguenea quinquenervia
, and
Trevoa trinervis
. Nearly full-length 16S rDNAs were sequenced from strains of
Frankia
living in nodules of
Ceanothus americanus
,
C. hystrix
,
Coriaria arborea
, and
Trevoa trinervis
. Partial sequences also were obtained from
Frankia
strains isolated and cultured from the nodules of
C. hystrix
,
Discaria serratifolia
,
D. trinervis
,
Retanilla ephedra
,
T. quinquenervia
, and
T. trinervis
(Rhamnaceae). Comparison of these sequences and other published sequences of
Frankia
16S rDNA reveals that the microsymbionts and isolated strains from the two plant families form a distinct phylogenetic clade, except for those from
C. americanus
. All sequences in the clade have a common 2-base deletion compared with other
Frankia
strains. Sequences from
C. americanus
nodules lack the deletion and cluster with
Frankia
strains infecting plants of the family Rosaceae. Published plant phylogenies (based on chloroplast
rbcL
sequences) group the members of the families Elaeagnaceae and Rhamnaceae together in the same clade. Thus, with the exception of
C. americanus
, actinorhizal plants of these families and their
Frankia
microsymbionts share a common symbiotic origin.
Sequence Analysis, Overexpression, and Antisense Inhibition of a β-Xylosidase Gene,
xylA
, from
Aspergillus oryzae
KBN616
Authors: Kitamoto Noriyuki , Yoshino Shoko , Ohmiya Kunio , Tsukagoshi Norihiro 
Published: December 2019

ABSTRACT

β-Xylosidase secreted by the shoyu koji mold,
Aspergillus oryzae
, is the key enzyme responsible for browning of soy sauce. To investigate the role of β-xylosidase in the brown color formation, a major β-xylosidase, XylA, and its encoding gene were characterized. β-Xylosidase XylA was purified to homogeneity from culture filtrates of
A. oryzae
KBN616. The optimum pH and temperature of the enzyme were found to be 4.0 and 60°C, respectively, and the molecular mass was estimated to be 110 kDa based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The
xylA
gene comprises 2,397 bp with no introns and encodes a protein consisting of 798 amino acids (86,475 Da) with 14 potential N-glycosylation sites. The deduced amino acid sequence shows high similarity to
Aspergillus nidulans
XlnD (70%),
Aspergillus niger
XlnD (64%), and
Trichoderma reesei
BxII (63%). The
xylA
gene was overexpressed under control of the strong and constitutive
A. oryzae TEF1
promoter. One of the
A. oryzae
transformants produced approximately 13 times more of the enzyme than did the host strain. The partial-length antisense
xylA
gene expressed under control of the
A. oryzae TEF1
promoter decreased the β-xylosidase level in
A. oryzae
to about 20% of that of the host strain.