bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Soil pH on the Biodegradation of Chlorpyrifos and Isolation of a Chlorpyrifos-Degrading Bacterium
Authors: Singh Brajesh K. , Walker Allan , Morgan J. Alun W. , Wright Denis J. 
Published: September 2003

ABSTRACT

We examined the role of microorganisms in the degradation of the organophosphate insecticide chlorpyrifos in soils from the United Kingdom and Australia. The kinetics of degradation in five United Kingdom soils varying in pH from 4.7 to 8.4 suggested that dissipation of chlorpyrifos was mediated by the cometabolic activities of the soil microorganisms. Repeated application of chlorpyrifos to these soils did not result in the development of a microbial population with an enhanced ability to degrade the pesticide. A robust bacterial population that utilized chlorpyrifos as a source of carbon was detected in an Australian soil. The enhanced ability to degrade chlorpyrifos in the Australian soil was successfully transferred to the five United Kingdom soils. Only soils with a pH of ≥6.7 were able to maintain this degrading ability 90 days after inoculation. Transfer and proliferation of degrading microorganisms from the Australian soil to the United Kingdom soils was monitored by molecular fingerprinting of bacterial 16S rRNA genes by PCR-denaturing gradient gel electrophoresis (DGGE). Two bands were found to be associated with enhanced degradation of chlorpyrifos. Band 1 had sequence similarity to enterics and their relatives, while band 2 had sequence similarity to strains of
Pseudomonas
. Liquid enrichment culture using the Australian soil as the source of the inoculum led to the isolation of a chlorpyrifos-degrading bacterium. This strain had a 16S rRNA gene with a sequence identical to that of band 1 in the DGGE profile of the Australian soil. DNA probing indicated that genes similar to known organophosphate-degrading (
opd
) genes were present in the United Kingdom soils. However, no DNA hybridization signal was detected for the Australian soil or the isolated degrader. This indicates that unrelated genes were present in both the Australian soil and the chlorpyrifos-degrading isolate. These results are consistent with our observations that degradation of chlorpyrifos in these systems was unusual, as it was growth linked and involved complete mineralization. As the 16S rRNA gene of the isolate matched a visible DGGE band from the Australian soil, the isolate is likely to be both prominent and involved in the degradation of chlorpyrifos in this soil.
Identification of
cry1I-
Type Genes from
Bacillus thuringiensis
Strains and Characterization of a Novel
cry1I-
Type Gene
Authors: Song Fuping , Zhang Jie , Gu Aixing , Wu Yue , Han Lanlan , He Kanglai , Chen Zhongyi , Yao Jiang , Hu Yuqin , Li Guoxun , Huang Dafang 
Published: September 2003

ABSTRACT

A PCR-restriction fragment length polymorphism method for identification of
cry1I
-type genes from
Bacillus thuringiensis
was established by designing a pair of universal primers based on the conserved regions of the genes to amplify 1,548-bp
cry1I-
type gene fragments. Amplification products were digested with the
Bsp
119I and
Ban
I enzymes, and four kinds of known
cry1I
-type genes were successfully identified. The results showed that
cry1I
-type genes appeared in 95 of 115
B. thuringiensis
isolates and 7 of 13 standard strains. A novel
cry1I
-type gene was found in one standard strain and six isolates. The novel
cry1I
gene was cloned from
B. thuringiensis
isolate Btc007 and subcloned into vector pET-21b. Then it was overexpressed in
Escherichia coli
BL21(DE3). The expressed product was shown to be toxic to the diamondback moth (
Plutella xylostella
), Asian corn borer (
Ostrinia furnacalis
), and soybean pod borer (
Leguminivora glycinivorella
). However, it was not toxic to the cotton bollworm (
Helicoverpa armigera
), beet armyworm (
Spodoptera exigua
), or elm leaf beetle (
Pyrrhalta aenescens
) in bioassays. Subsequently, the Cry protein encoded by this novel
cry
gene was designated Cry1Ie1 by the
B. thuringiensis
δ-endotoxin nomenclature committee.
Detection of Staphylococcal Enterotoxin B via Biomolecular Interaction Analysis Mass Spectrometry
Authors: Nedelkov Dobrin , Nelson Randall W. 
Published: September 2003

ABSTRACT

Detection of
Staphylococcus
enterotoxin B (SEB) by biomolecular interaction analysis mass spectrometry (BIA/MS) is presented in this work. The BIA/MS experiments were based on a surface plasmon resonance (SPR) MS immunoassay that detects affinity-captured SEB both via SPR and by means of exact and direct mass measurement by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Experiments were performed with standard samples and food samples to assess the BIA/MS limit of detection for SEB and to set the experimental parameters for proper quantitation. Single and double SPR referencing was performed to accurately estimate the amount of the bound toxin. Reproducible detection of 1 ng of SEB per ml, corresponding to affinity capture and MS analysis of ∼500 amol of SEB, was readily achieved from both the standard and mushroom samples. A certain amount of SEB degradation was indicated by the signals in the mass spectra. The combination of MS with SPR-based methods of detection creates a unique approach capable of quantifying and qualitatively analyzing protein toxins from pathogenic organisms.
Biotransformation of 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-Hexaazaisowurtzitane (CL-20) by Denitrifying
Pseudomonas
sp. Strain FA1
Authors: Bhushan Bharat , Paquet Louise , Spain Jim C. , Hawari Jalal 
Published: September 2003

ABSTRACT

The microbial and enzymatic degradation of a new energetic compound, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), is not well understood. Fundamental knowledge about the mechanism of microbial degradation of CL-20 is essential to allow the prediction of its fate in the environment. In the present study, a CL-20-degrading denitrifying strain capable of utilizing CL-20 as the sole nitrogen source,
Pseudomonas
sp. strain FA1, was isolated from a garden soil. Studies with intact cells showed that aerobic conditions were required for bacterial growth and that anaerobic conditions enhanced CL-20 biotransformation. An enzyme(s) involved in the initial biotransformation of CL-20 was shown to be membrane associated and NADH dependent, and its expression was up-regulated about 2.2-fold in CL-20-induced cells. The rates of CL-20 biotransformation by the resting cells and the membrane-enzyme preparation were 3.2 ± 0.1 nmol h
−1
mg of cell biomass
−1
and 11.5 ± 0.4 nmol h
−1
mg of protein
−1
, respectively, under anaerobic conditions. In the membrane-enzyme-catalyzed reactions, 2.3 nitrite ions (NO
2
−
), 1.5 molecules of nitrous oxide (N
2
O), and 1.7 molecules of formic acid (HCOOH) were produced per reacted CL-20 molecule. The membrane-enzyme preparation reduced nitrite to nitrous oxide under anaerobic conditions. A comparative study of native enzymes, deflavoenzymes, and a reconstituted enzyme(s) and their subsequent inhibition by diphenyliodonium revealed that biotransformation of CL-20 is catalyzed by a membrane-associated flavoenzyme. The latter catalyzed an oxygen-sensitive one-electron transfer reaction that caused initial N denitration of CL-20.
PAC1
, a pH-Regulatory Gene from
Fusarium verticillioides
Authors: Flaherty Joseph E. , Pirttilä Anna Maria , Bluhm Burton H. , Woloshuk Charles P. 
Published: September 2003

ABSTRACT

Fumonisins are a group of mycotoxins that contaminate maize and cause leukoencephalomalacia in equine, pulmonary edema in swine, and promote cancer in mice. Fumonisin biosynthesis in
Fusarium verticillioides
is repressed by nitrogen and alkaline pH. We cloned a
PACC
-like gene (
PAC1
) from
F. verticillioides
.
PACC
genes encode the major transcriptional regulators of several pH-responsive pathways in other filamentous fungi. In Northern blot analyses, a
PAC1
probe hybridized to a 2.2-kb transcript present in
F. verticillioides
grown at alkaline pH. A mutant of
F. verticillioides
with a disrupted
PAC1
gene had severely impaired growth at alkaline pH. The mutant produced more fumonisin than the wild type when grown on maize kernels and in a synthetic medium buffered at an acidic pH, 4.5. The mutant, but not the wild type, also produced fumonisin B
1
when mycelia were resuspended in medium buffered at an alkaline pH, 8.4. Transcription of
FUM1
, a gene involved in fumonisin biosynthesis, was correlated with fumonisin production. We conclude that
PAC1
is required for growth at alkaline pH and that
Pac1
may have a role as a repressor of fumonisin biosynthesis under alkaline conditions.
Expression Levels of the Yeast Alcohol Acetyltransferase GenesATF1,Lg-ATF1, andATF2Control the Formation of a Broad Range of Volatile Esters
Authors: Verstrepen Kevin J. , Van Laere Stijn D. M. , Vanderhaegen Bart M. P. , Derdelinckx Guy , Dufour Jean-Pierre , Pretorius Isak S. , Winderickx Joris , Thevelein Johan M. , Delvaux Freddy R. 
Published: September 2003

ABSTRACTVolatile aroma-active esters are responsible for the fruity character of fermented alcoholic beverages such as beer and wine. Esters are produced by fermenting yeast cells in an enzyme-catalyzed intracellular reaction. In order to investigate and compare the roles of the knownSaccharomyces cerevisiaealcohol acetyltransferases, Atf1p, Atf2p and Lg-Atf1p, in volatile ester production, the respective genes were either deleted or overexpressed in a laboratory strain and a commercial brewing strain. Subsequently, the ester formation of the transformants was monitored by headspace gas chromatography and gas chromatography combined with mass spectroscopy (GC-MS). Analysis of the fermentation products confirmed that the expression levels ofATF1andATF2greatly affect the production of ethyl acetate and isoamyl acetate. GC-MS analysis revealed that Atf1p and Atf2p are also responsible for the formation of a broad range of less volatile esters, such as propyl acetate, isobutyl acetate, pentyl acetate, hexyl acetate, heptyl acetate, octyl acetate, and phenyl ethyl acetate. With respect to the esters analyzed in this study, Atf2p seemed to play only a minor role compared to Atf1p. Theatf1Δatf2Δ double deletion strain did not form any isoamyl acetate, showing that together, Atf1p and Atf2p are responsible for the total cellular isoamyl alcohol acetyltransferase activity. However, the double deletion strain still produced considerable amounts of certain other esters, such as ethyl acetate (50% of the wild-type strain), propyl acetate (50%), and isobutyl acetate (40%), which provides evidence for the existence of additional, as-yet-unknown ester synthases in the yeast proteome. Interestingly, overexpression of different alleles ofATF1andATF2led to different ester production rates, indicating that differences in the aroma profiles of yeast strains may be partially due to mutations in theirATFgenes.
Enhanced Production of α-Galactosyl Epitopes by Metabolically Engineered
Pichia pastoris
Authors: Shao Jun , Hayashi Takahisa , Wang Peng George 
Published: September 2003

ABSTRACT

A metabolically engineered
Pichia pastori
s strain was constructed that harbored three heterologous enzymes: an S11E mutated sucrose synthase from
Vigna radiata
, a truncated UDP-glucose C4 epimerase from
Saccharomyces cerevisiae
, and a truncated bovine α-1,3-galactosyltransferase. Each gene has its own methanol-inducible alcohol oxidase 1 promoter and transcription terminator on the chromosomal DNA of
P. pastori
s strain GS115. The proteins were coexpressed intracellularly under the induction of methanol. After permeabilization, the whole
P. pastori
s cells were used to synthesize α-galactosyl (α-Gal) trisaccharide (Galα1,3Galβ1,4Glc) with in situ regeneration of UDP-galactose. Up to 28 mM α-Gal was accumulated in a 200-ml reaction. The
Pichia
system described here is simple and flexible. This work demonstrates that recombinant
P. pastori
s is an excellent alternative to
Escherichia coli
transformants in large-scale synthesis of oligosaccharides.
Prevalence of
Escherichia coli
O157 in Cattle Feeds in Midwestern Feedlots
Authors: Dodd Charles C. , Sanderson Michael W. , Sargeant Jan M. , Nagaraja T. G. , Oberst Richard D. , Smith Robert A. , Griffin D. Dee 
Published: September 2003

ABSTRACT

Comparisons of enrichment methods (with or without antibiotics and with or without a preenrichment step) using gram-negative (GN) broth or tryptic soy broth (TSB) were conducted with feeds inoculated with
Escherichia coli
O157:H7. TSB was more sensitive than GN broth, and TSB with a preenrichment step followed by TSB with antibiotics was more sensitive than plain TSB enrichment, in detecting
E. coli
O157 in inoculated feeds. Feed samples were collected from feed bunks from 54 feedlots to determine the prevalence of
E. coli
O157 in cattle feeds. TSB preenrichment followed by TSB with antibiotics and the standard GN broth enrichment were used for each feed sample. All samples underwent immunomagnetic separation and were plated onto sorbitol MacConkey agar with cefixime and potassium tellurite. Identification of
E. coli
O157 was based on indole production, positive latex agglutination for O157 antigen, API 20E test strip results, PCR for the
eaeA
gene, and the presence of at least one Shiga toxin.
E. coli
O157 was detected in 52 of 504 feed samples (10.3%) by using GN broth enrichment and in 46 of 504 feed samples (9.1%) by using TSB followed by TSB supplemented with cefixime and vancomycin.
E. coli
O157 was detected in 75 of 504 feed bunk samples (14.9%) by one or both methods. There was no correlation between
E. coli
O157 prevalence and generic coliform counts in feeds. The prevalence of
E. coli
O157 in cattle feed warrants further studies to increase our knowledge of the on-farm ecology of
E. coli
O157 in order to develop strategies to prevent food-borne disease in humans.
Isolation of Strains Belonging to the Cosmopolitan
Polynucleobacter necessarius
Cluster from Freshwater Habitats Located in Three Climatic Zones
Authors: Hahn Martin W. 
Published: September 2003

ABSTRACT

More than 40 bacterial strains belonging to the cosmopolitan
Polynucleobacter necessarius
cluster (
Betaproteobacteria
) were isolated from a broad spectrum of freshwater habitats located in three climatic zones. Sequences affiliated with the freshwater
P. necessarius
cluster are among the most frequently detected in studies on bacterial diversity in freshwater ecosystems. Despite this frequent detection with culture-independent techniques and the cosmopolitan occurrence of members affiliated with this cluster, no isolates have been reported thus far. The isolated strains have been obtained from lakes, ponds, and rivers in central Europe, the People's Republic of China, and East Africa by use of the filtration-acclimatization method. The 16S rRNA gene sequences of the isolates are 98.8 to 100% identical to reference sequences obtained by various authors by use of culture-independent methods. The isolates, aerobic heterotrophs, grew on a wide range of standard complex media and formed visible colonies on agar plates. Thus, the previous lack of isolates cannot be explained by a lack of appropriate media. Most of the isolates possess, under a wide range of culture conditions, very small cells (<0.1 μm
3
), even when grown in medium containing high concentrations of organic substances. Thus, these strains are obligate ultramicrobacteria. The obtained strains have a C-shaped cell morphology which is very similar to that of recently isolated ultramicrobacterial Luna cluster strains (
Actinobacteria
) and the SAR11 cluster strains (
Alphaproteobacteria
).
Nitrilotriacetate Stimulation of Anaerobic Fe(III) Respiration by Mobilization of Humic Materials in Soil
Authors: Luu Y. , Ramsay B. A. , Ramsay J. A. 
Published: September 2003

ABSTRACT
An enrichment culture capable of naphthalene mineralization reduced Fe(III) oxides without direct contact in anaerobic soil microcosms when the Fe(III) was placed in dialysis membranes or entrapped within alginate beads. Both techniques demonstrated that a component in soil, possibly humic materials, facilitated Fe(III) reduction when direct contact between cells and Fe(III) was not possible. The addition of the synthetic Fe(III) chelator, nitrilotriacetic acid (NTA), to soil enhanced Fe(III) reduction across the dialysis membrane and alginate beads, with the medium changing from clear to a dark brown color. An NTA-soil extract was more effective in Fe(III) reduction than the extracted soil itself. Characteristics of the NTA extract were consistent with that of humic substances. The results indicate that NTA improved Fe(III) reduction not by Fe(III) solubilization but by extraction of humic substances from soil into the aqueous medium. This is the first study in which stimulation of Fe(III) reduction through the addition of chemical chelators is shown to be due to the extraction of electron-shuttling compounds from the soil and not to solubilization of the Fe(III) and indicates that mobilization of humic materials could be an important component of anaerobic biostimulation.
Waterborne Outbreak of Gastroenteritis Associated with a Norovirus
Authors: Parshionikar Sandhya U. , Willian-True Sandra , Fout G. Shay , Robbins David E. , Seys Scott A. , Cassady Joslyn D. , Harris Richard 
Published: September 2003

ABSTRACT
The Wyoming Department of Health investigated an outbreak of acute gastroenteritis among persons who dined at a tourist saloon in central Wyoming during October 2001. Human caliciviruses (HuCVs) were suspected as the etiological agent of the outbreak based on the incubation period, duration of illness, and symptoms observed in ill patrons. A retrospective cohort study demonstrated that ill patrons were 4.5 times more likely to have exposure to drinking water and/or ice than nonill patrons. No food items were associated with illness. An environmental investigation gave evidence that the saloon's groundwater was contaminated with sewage. Water from the saloon's only well was processed for viruses. The processed water sample and stool samples collected from three ill patrons were analyzed by reverse transcription-PCR (RT-PCR) for the presence of HuCV. All positive RT-PCR results were confirmed by sequence and phylogenetic analyses of cloned RT-PCR products. A genogroup I, subtype 3, HuCV stain was found to be present in the well water sample and two stool samples. In addition, a genogroup II, subtype 6, strain was detected in one stool sample. The identification of the same HuCV strain in both the well water and stool samples strongly suggests a link between exposure to well water and the outbreak of gastroenteritis. The presence of a genogroup II, subtype 6, strain in one of the stool samples suggests that multiple HuCV strains may have been involved in this outbreak. The laboratory isolation of HuCV strains from outbreak-associated drinking water is relatively novel in the United States. This investigation outlines the procedure for virus isolation and illustrates the utility of RT-PCR for the identification of HuCV in large volumes of water and stool samples obtained during outbreaks of acute nonbacterial gastroenteritis.
Diversity of
Bacillus thuringiensis
Strains from Latin America with Insecticidal Activity against Different Mosquito Species
Authors: Ibarra Jorge E. , del Rincón M. Cristina , Ordúz Sergio , Noriega David , Benintende Graciela , Monnerat Rose , Regis Leda , de Oliveira Cláudia M. F. , Lanz Humberto , Rodriguez Mario H. , Sánchez Jorge , Peña Guadalupe , Bravo Alejandra 
Published: September 2003

ABSTRACT

The characterization of selected
Bacillus thuringiensis
strains isolated from different Latin America countries is presented. Characterization was based on their insecticidal activity against
Aedes aegypti
,
Culex quinquefasciatus
, and
Anopheles albimanus
larvae, scanning electron microscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and plasmid profiles as well as PCR analysis using novel general and specific primers for
cry
and
cyt
genes encoding proteins active against mosquitoes (
cyt1
,
cyt2
,
cry2
,
cry4A
,
cry4B
,
cry10
,
cry11
,
cry17
,
cry19
,
cry24
,
cry25
,
cry27
,
cry29
,
cry30
,
cry32
,
cry39
, and
cry40
). Strains LBIT315, LBIT348, and IB604 showed threefold higher mosquitocidal activity against
A
.
aegypti
and
C
.
quinquefasciatus
larvae than
B
.
thuringiensis
subsp.
israelensis
and displayed high similarities with the
B
.
thuringiensis
subsp.
israelensis
used in this study with regard to protein and plasmid profiles and the presence of
cry
genes. Strain 147-8906 has activity against
A
.
aegypti
similar to that of
B
.
thuringiensis
subsp.
israelensis
but has different protein and plasmid profiles. This strain, harboring
cry11
,
cry30
,
cyt1
, and
cyt2
genes, could be relevant for future resistance management interventions. Finally, the PCR screening strategy presented here led us to identify a putative novel
cry11B
gene.
Involvement of a Sialic Acid-Binding Lectin with Hemagglutination and Hydrophobicity of
Flavobacterium psychrophilum
Authors: Møller Jeannette Dan , Larsen Jens Laurits , Madsen Lone , Dalsgaard Inger 
Published: September 2003

ABSTRACT

Strains of
Flavobacterium psychrophilum
were studied for their ability to adhere and cause agglutination of erythrocytes and yeast cells. Strains of the serotype Th showed low or no hemagglutinating (HA) properties toward human, avian, bovine, and rainbow trout erythrocytes, whereas strains of serotype Fd and Fp
T
exhibited distinct HA properties. None of the strains was able to cause agglutination of yeast cells. Greater adherence specificity toward rainbow trout blood cells was seen for the HA-positive strains. Growth at 5°C, compared to that at 15°C, induced an increase in the hemagglutination of some strains. HA activities of
F. psychrophilum
were inhibited only by sialic acid (
N
-acetyl-neuraminic acid), heat treatment at 65°C, and proteinase K treatment and not by any of seven other carbohydrates, periodate oxidation, or treatment with trypsin. The supernatant from washed bacterial cells also showed some HA properties. All strains were shown to be highly hydrophobic by the hydrophobic interaction chromatography test, although some contradictions to the results of the salt aggregation test (showing some strains as less hydrophobic) were seen. These results indicate that the aggregation of
F. psychrophilum
and erythrocytes depend on a lectin present on the surface of HA-positive
F. psychrophilum
strains and absent on HA-negative strains. This lectin reacts specifically with sialic acid. The adhesion differences observed for
F. psychrophilum
strains do not appear to correlate with the virulence but still provide insights into the interaction of
F. psychrophilum
and rainbow trout.