bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calicivirus Inactivation by Nonionizing (253.7-Nanometer-Wavelength [UV]) and Ionizing (Gamma) Radiation
Authors: de Roda Husman Ana Maria , Bijkerk Paul , Lodder Willemijn , van den Berg Harold , Pribil Walter , Cabaj Alexander , Gehringer Peter , Sommer Regina , Duizer Erwin 
Published: September 2004

ABSTRACT

Noroviruses (previously Norwalk-like viruses) are the most common viral agents associated with food- and waterborne outbreaks of gastroenteritis. In the absence of culture methods for noroviruses, animal caliciviruses were used as model viruses to study inactivation by nonionizing (253.7-nm-wavelength [UV]) and ionizing (gamma) radiation. Here, we studied the respiratory feline calicivirus (FeCV) and the presumed enteric canine calicivirus (CaCV) and compared them with the well-studied bacteriophage MS2. When UV irradiation was used, a 3-log
10
reduction was observed at a fluence of 120 J/m
2
in the FeCV suspension and at a fluence of 200 J/m
2
for CaCV; for the more resistant phage MS2 there was a 3-log
10
reduction at a fluence of 650 J/m
2
. Few or no differences were observed between levels of UV inactivation in high- and low-protein-content virus stocks. In contrast, ionizing radiation could readily inactivate MS2 in water, and there was a 3-log
10
reduction at a dose of 100 Gy, although this did not occur when the phage was diluted in high-protein-content stocks of CaCV or FeCV. The low-protein-content stocks showed 3-log
10
reductions at a dose of 500 Gy for FeCV and at a dose of 300 for CaCV. The inactivation rates for both caliciviruses with ionizing and nonionizing radiation were comparable but different from the inactivation rates for MS2. Although most FeCV and CaCV characteristics, such as overall particle and genome size and structure, are similar, the capsid sequences differ significantly, making it difficult to predict human norovirus inactivation. Adequate management of UV and gamma radiation processes for virus inactivation should limit public health risks.
The
gnyRDBHAL
Cluster Is Involved in Acyclic Isoprenoid Degradation in
Pseudomonas aeruginosa
Authors: Díaz-Pérez A. L. , Zavala-Hernández A. N. , Cervantes C. , Campos-García J. 
Published: September 2004

ABSTRACT

Pseudomonas aeruginosa
PAO1 mutants affected in the ability to degrade acyclic isoprenoids were isolated with transposon mutagenesis. The
gny
cluster (for geranoyl), which encodes the enzymes involved in the lower pathway of acyclic isoprenoid degradation, was identified. The
gny
cluster is constituted by five probable structural genes,
gnyDBHAL
, and a possible regulatory gene,
gnyR
. Mutations in the
gnyD
,
gnyB
,
gnyA
, or
gnyL
gene caused inability to assimilate acyclic isoprenoids of the citronellol family of compounds. Transcriptional analysis showed that expression of the
gnyB
gene was induced by citronellol and repressed by glucose, whereas expression of the
gnyR
gene had the opposite behavior. Western blot analysis of citronellol-grown cultures showed induction of biotinylated proteins of 70 and 73 kDa, which probably correspond to 3-methylcrotonoyl-coenzyme A (CoA) carboxylase and geranoyl-CoA carboxylase (GCCase) alpha subunits, respectively. The 73-kDa biotinylated protein, identified as the α-GCCase subunit, is encoded by
gnyA
. Intermediary metabolites of the isoprenoid pathway, citronellic and geranic acids, were shown to accumulate in
gnyB
and
gnyA
mutants. Our data suggest that the protein products encoded in the
gny
cluster are the β and α subunits of geranoyl-CoA carboxylase (GnyB and GnyA), the citronelloyl-CoA dehydrogenase (GnyD), the γ-carboxygeranoyl-CoA hydratase (GnyH), and the 3-hydroxy-γ-carboxygeranoyl-CoA lyase (GnyL). We conclude that the
gnyRDBHAL
cluster is involved in isoprenoid catabolism.
Comparison of ATPase-Encoding Type III Secretion SystemhrcNGenes in Biocontrol Fluorescent Pseudomonads and in Phytopathogenic Proteobacteria
Authors: Rezzonico Fabio , Défago Geneviève , Moënne-Loccoz Yvan 
Published: September 2004

ABSTRACTType III protein secretion systems play a key role in the virulence of many pathogenic proteobacteria, but they also occur in nonpathogenic, plant-associated bacteria. Certain type III protein secretion genes (e.g.,hrcC) have been found inPseudomonassp. strain SBW25 (and other biocontrol pseudomonads), but other type III protein secretion genes, such as the ATPase-encoding genehrcN, have not been found. Using both colony hybridization and a PCR approach, we show here thathrcNis nevertheless present in many biocontrol fluorescent pseudomonads. The phylogeny of biocontrolPseudomonasstrains based on partialhrcNsequences was largely congruent with the phylogenies derived from analyses ofrrs(encoding 16S rRNA) and, to a lesser extent, biocontrol genes, such asphlD(for 2,4-diacetylphloroglucinol production) andhcnBC(for HCN production). Most biocontrol pseudomonads clustered separately from phytopathogenic proteobacteria, including pathogenic pseudomonads, in thehrcNtree. The exception was strain KD, which clustered with phytopathogenic pseudomonads, such asPseudomonas syringae, suggesting thathrcNwas acquired from the latter species. Indeed, strain KD (unlike strain SBW25) displayed the same organization of thehrpJoperon, which containshrcN, asP. syringae. These results indicate that the occurrence ofhrcNin most biocontrol pseudomonads is not the result of recent horizontal gene transfer from phytopathogenic bacteria, although such transfer might have occurred for a minority of biocontrol strains.
Clonality and Diversity of the Fish Pathogen
Lactococcus garvieae
in Mediterranean Countries
Authors: Eyngor Marina , Zlotkin Amir , Ghittino Claudio , Prearo Marino , Douet Diane-Gaëlle , Chilmonczyk Stefan , Eldar Avi 
Published: September 2004

ABSTRACT

Infection with
Lactococcus garvieae
is considered the most important risk factor for the European trout industry, and the losses are approximately 50% of the total production. To improve our understanding of the genetic links among strains originating from different countries, we examined the population structure of
L. garvieae
by comparing 81 strains isolated from different sources and ecosystems (41 farms in six countries) in which the bacterium is commonly found. Genetic similarities (as assessed with molecular tools, including restriction fragment length polymorphism ribotyping with two endonucleases) were compared with serological data. The combined results reveal that in endemic sites the bacterial population displays a clonal structure, whereas bacterial diversity characterizes sites where the infection is sporadic.
Modulation of
Aspergillus awamori
Thaumatin Secretion by Modification of
bipA
Gene Expression
Authors: Lombraña Marta , Moralejo Francisco J. , Pinto Rosa , Martín Juan F. 
Published: September 2004

ABSTRACT

Two different strains,
Aspergillus awamori
TGDTh-4 and
A. awamori
TGP-3 overexpressing a synthetic gene encoding the plant sweet protein thaumatin, showed an unfolded protein response. To facilitate protein secretion, the chaperone BiPA gene was expressed in
A. awamori
under control of the strong constitutive promoter of the
gpdA
gene. A good correlation was observed between the level of the
bipA
transcript in different strains and the amount of thaumatin secreted. Thaumatin secretion was increased 2- to 2.5-fold in transformants overexpressing the
bipA
gene compared with the parental strain. Secretion of the homologous proteins α-amylase and glucoamylase was not affected by the
bipA
gene overexpression. The requirement for BiPA for secretion of thaumatin was confirmed by attenuation of the endogenous
bipA
gene expression with an antisense RNA cassette. The decrease in
bipA
expression reduced the amount of secreted thaumatin up to 80% without affecting the secretion of the homologous α-amylase and glucoamylase proteins. The BiPA protein is, therefore, very important for secretion of some heterologous proteins, such as thaumatin in
A. awamori
.
Genotyping and Toxigenic Potential ofBacillus subtilisandBacillus pumilusStrains Occurring in Industrial and Artisanal Cured Sausages
Authors: Matarante Alessandra , Baruzzi Federico , Cocconcelli Pier Sandro , Morea Maria 
Published: September 2004

ABSTRACTArtisanal and industrial sausages were analyzed for their aerobic, heat-resistant microflora to assess whether new emerging pathogens could be present amongBacillusstrains naturally contaminating cured meat products. Sixty-four isolates were characterized by randomly amplified polymorphic DNA (RAPD)-PCR and fluorescent amplified fragment length polymorphism (fAFLP). The biotypes, identified by partial 16S rRNA gene sequence analysis, belonged toBacillus subtilis,Bacillus pumilus, andBacillus amyloliquefaciensspecies. Both RAPD-PCR and fAFLP analyses demonstrated that a high genetic heterogeneity is present in theB. subtilisgroup even in strains harvested from the same source, making it possible to isolate 56 different biotypes. Moreover, fAFLP analysis made it possible to distinguishB. subtilisfromB. pumilusstrains. The strains were characterized for their toxigenic potential by molecular, physiological, and immunological techniques. Specific PCR analyses revealed the absence of DNA sequences related to HBL, BcET, NHE, and entFMBacillus cereusenterotoxins and the enzymes sphingomyelinase Sph and phospholipase PI-PLC in all strains; also, the immunological analyses showed thatBacillusstrains did not react with NHE- and HBL-specific antibodies. However, some isolates were found to be positive for hemolytic and lecithinase activity. The absence of toxigenic potential inBacillusstrains from the sausages analyzed indicates that these products can be considered safe under the processing conditions they were produced; however, great care should be taken when the ripening time is shortened, particularly in the case of traditional sausages, which could contain high amounts ofBacillusstrains and possibly someB. cereuscells.
Identification of Specific In Vivo-Induced (ivi) Genes inYersinia ruckeriand Analysis of Ruckerbactin, a Catecholate Siderophore Iron Acquisition System
Authors: Fernández L. , Márquez I. , Guijarro J. A. 
Published: September 2004

ABSTRACTThis work reports the utilization of an in vivo expression technology system to identify in vivo-induced (ivi) genes inYersinia ruckeriafter determination of the conditions needed for its selection in fish. Fourteen clones were selected, and the cloned DNA fragments were analyzed after partial sequencing. In addition to sequences with no significant similarity, homology with genes encoding proteins putatively involved in two-component and type IV secretion systems, adherence, specific metabolic functions, and others were found. Among these sequences, four were involved in iron acquisition through a catechol siderophore (ruckerbactin). Thus, unlike other pathogenic yersiniae producing yersiniabactin,Y. ruckerimight be able to produce and utilize only this phenolate. The genetic organization of the ruckerbactin biosynthetic and uptake loci was similar to that of theEscherichia colienterobactin gene cluster. GenesrucCandrupG, putative counterparts ofE. coli entCandfepG, respectively, involved in the biosynthesis and transport of the iron siderophore complex, respectively, were analyzed further. Thus, regulation of expression by iron and temperature and their presence in otherY. ruckerisiderophore-producing strains were confirmed for these two loci. Moreover, 50% lethal dose values 100-fold higher than those of the wild-type strain were obtained with therucCisogenic mutant, showing the importance of ruckerbactin in the pathogenesis caused by this microorganism.
In Situ Monitoring of Streptothricin Production byStreptomyces rocheiF20 in Soil and Rhizosphere
Authors: Anukool Usanee , Gaze William H. , Wellington Elizabeth M. H. 
Published: September 2004

ABSTRACTThe onset of streptothricin (ST) biosynthesis inStreptomyces rocheiF20 was studied by using reverse transcription-PCR (RT-PCR) to detect transcripts of ST genes during growth in liquid medium, soil, and the rhizosphere. In situ results correlated with those obtained in vitro, illustrating the growth phase-dependent manner of ST production by F20. Maximal transcription of ST resistance (sttR) and biosynthesis (sttA) genes occurred during the transition between the exponential and stationary phases of growth, when the specific growth rate (μ) started to decline. A higher level of gene expression ofsttRversussttAwas observed in all experiments. In liquid culture, maximal transcript accumulation of thesttAgene was only ca. 40% that of thesttRgene.sttAandsttRmRNAs were detected in soil containing approximately 106CFU of growing cells g of soil−1.sttRmRNA was detected in sterile and nonsterile rhizosphere colonized with growing mycelium of F20 at 1.2 × 106and 4.0 × 105CFU g of soil−1, respectively. However, neithersttRnorsttAtranscripts were detected by RT-PCR in the rhizoplane, which supported a lower population density of F20 than the rhizosphere.
Anaerobic Growth of
Bacillus mojavensis
and
Bacillus subtilis
Requires Deoxyribonucleosides or DNA
Authors: Folmsbee Martha J. , McInerney Michael J. , Nagle David P. 
Published: September 2004

ABSTRACT

Bacillus mojavensis
strains JF-2 (ATCC 39307), ROB2, and ABO21191
T
and
Bacillus subtilis
strains 168 (ATCC 23857) and ATCC 12332 required four deoxyribonucleosides or DNA for growth under strict anaerobic conditions.
Bacillus licheniformis
strains L89-11 and L87-11,
Bacillus sonorensis
strain TG8-8, and
Bacillus cereus
(ATCC 14579) did not require DNA for anaerobic growth. The requirement for the deoxyribonucleosides or DNA did not occur under aerobic growth conditions. The addition of a mixture of five nucleic acid bases, four ribonucleotides, or four ribonucleosides to the basal medium did not replace the requirement of
B. mojavensis
JF-2 for the four deoxyribonucleosides. However, the addition of salmon sperm DNA, herring sperm DNA,
Escherichia coli
DNA, or synthetic DNA (single or double stranded) to the basal medium supported anaerobic growth. The addition of four deoxyribonucleosides to the basal medium allowed aerobic growth of
B. mojavensis
JF-2 in the presence of hydroxyurea.
B. mojavensis
did not grow in DNA-supplemented basal medium that lacked sucrose as the energy source. These data provide strong evidence that externally supplied deoxyribonucleosides can be used to maintain a balanced deoxyribonucleotide pool for DNA synthesis and suggest that ribonucleotide reductases may not be essential to the bacterial cell cycle nor are they necessarily part of a minimal bacterial genome.
Degradation of Estrogens by
Rhodococcus zopfii
and
Rhodococcus equi
Isolates from Activated Sludge in Wastewater Treatment Plants
Authors: Yoshimoto Takeshi , Nagai Fumiko , Fujimoto Junji , Watanabe Koichi , Mizukoshi Harumi , Makino Takashi , Kimura Kazumasa , Saino Hideyuki , Sawada Haruji , Omura Hiroshi 
Published: September 2004

ABSTRACT

We have isolated four strains of
Rhodococcus
which specifically degrade estrogens by using enrichment culture of activated sludge from wastewater treatment plants. Strain Y 50158, identified as
Rhodococcus zopfii
, completely and rapidly degraded 100 mg of 17β-estradiol, estrone, estriol, and ethinyl estradiol/liter, as demonstrated by thin-layer chromatography and gas chromatography-mass spectrometry analyses. Strains Y 50155, Y 50156, and Y 50157, identified as
Rhodococcus equi
, showed degradation activities comparable with that of Y 50158. Using the random amplified polymorphism DNA fingerprinting test, these three strains were confirmed to have been derived from different sources.
R. zopfii
Y 50158, which showed the highest activity among these four strains, revealed that the strain selectively degraded 17β-estradiol during jar fermentation, even when glucose was used as a readily utilizable carbon source in the culture medium. Measurement of estrogenic activities with human breast cancer-derived MVLN cells showed that these four strains each degraded 100 mg of 17β-estradiol/liter to 1/100 of the specific activity level after 24 h. It is thus suggested that these strains degrade 17β-estradiol into substances without estrogenic activity.
Transmission and Infectious Dose ofEscherichia coliO157:H7 in Swine
Authors: Cornick N. A. , Helgerson A. F. 
Published: September 2004

ABSTRACTEscherichia coliO157:H7 is only occasionally isolated from healthy swine, but some experimentally infected animals will shed the organism in their feces for at least 2 months. Potential explanations for the paucity of naturally occurring infections in swine, as compared to cattle, include a lack of animal-to-animal transmission so that the organism cannot be maintained within a herd, a high infectious dose, or herd management practices that prevent the maintenance of the organism in the gastrointestinal tract. We hypothesized that donor pigs infected withE. coliO157:H7 would transmit the organism to naïve pigs. We also determined the infectious dose and whether housing pigs individually on grated floors would decrease the magnitude or duration of fecal shedding. Infected donor pigs shedding <104CFU ofE. coliO157:H7 per g transmitted the organism to 6 of 12 naïve pigs exposed to them. The infectious dose ofE. coliO157:H7 for 3-month-old pigs was approximately 6 × 103CFU. There was no difference in the magnitude and duration of fecal shedding by pigs housed individually on grates compared to those housed two per pen on cement floors. These results suggest that swine do not have an innate resistance to colonization byE. coliO157:H7 and that they could serve as a reservoir host under suitable conditions.
Effect of Forage or Grain Diets with or without Monensin on Ruminal Persistence and Fecal
Escherichia coli
O157:H7 in Cattle
Authors: Van Baale M. J. , Sargeant J. M. , Gnad D. P. , DeBey B. M. , Lechtenberg K. F. , Nagaraja T. G. 
Published: September 2004

ABSTRACT

Twelve ruminally cannulated cattle, adapted to forage or grain diet with or without monensin, were used to investigate the effects of diet and monensin on concentration and duration of ruminal persistence and fecal shedding of
E. coli
O157:H7. Cattle were ruminally inoculated with a strain of
E. coli
O157:H7 (10
10
CFU/animal) made resistant to nalidixic acid (Nal
r
). Ruminal and fecal samples were collected for 11 weeks, and then cattle were euthanized and necropsied and digesta from different gut locations were collected. Samples were cultured for detection and enumeration of Nal
r
E. coli
O157:H7. Cattle fed forage diets were culture positive for
E. coli
O157:H7 in the feces for longer duration (
P
< 0.05) than cattle fed a grain diet. In forage-fed cattle, the duration they remained culture positive for
E. coli
O157:H7 was shorter (
P
< 0.05) when the diet included monensin. Generally, ruminal persistence of Nal
r
E. coli
O157:H7 was not affected by diet or monensin. At necropsy,
E. coli
O157:H7 was detected in cecal and colonic digesta but not from the rumen. Our study showed that cattle fed a forage diet were culture positive longer and with higher numbers than cattle on a grain diet. Monensin supplementation decreased the duration of shedding with forage diet, and the cecum and colon were culture positive for
E. coli
O157:H7 more often than the rumen of cattle.
RsbT and RsbV Contribute to σB-Dependent Survival under Environmental, Energy, and Intracellular Stress Conditions inListeria monocytogenes
Authors: Chaturongakul Soraya , Boor Kathryn J. 
Published: September 2004

ABSTRACTSigma B (σB) is a stress-responsive alternative sigma factor that has been identified in various gram-positive bacteria. Seven different regulators of sigma B (Rsbs) are located in thesigBoperons of bothBacillus subtilisandListeria monocytogenes. InB. subtilis, these proteins contribute to regulation of σBactivity by conveying environmental and energy stress signals through two well-established branches of a signal transduction pathway. RsbT contributes to regulation of σBactivity in response to environmental stresses, while RsbV contributes to σBactivation under both environmental and energy stresses inB. subtilis. To probeL. monocytogenesRsb roles in σB-mediated responses to various stresses, in-frame deletions were created inrsbTandrsbV. Phenotypic characterization of theL. monocytogenes rsbTandrsbVnull mutants revealed that both mutants were similar to the ΔsigBstrain in their abilities to survive under environmental stress conditions (exposure to synthetic gastric fluid, pH 2.5, acidified brain heart infusion broth [BHI], or oxidative stress [13 mM cumene hydroperoxide]). Under energy stress conditions (carbon starvation in defined media, entry into stationary phase, or reduced intracellular ATP), both ΔrsbTand ΔrsbVshowed survival reductions similar to that of the ΔsigBstrain. These observations suggest that the pathways for Rsb-dependent regulation of σBactivity differ betweenL. monocytogenesandB. subtilis. As σBalso activates transcription of theL. monocytogenes prfAP2 promoter, we evaluated virulence-associated characteristics of ΔprfAP1rsbTand ΔprfAP1rsbVdouble mutants in hemolysis and tissue culture assays. Both double mutants showed identical phenotypes to ΔprfAP1P2 and ΔprfAP1sigBdouble mutants, i.e., reduced hemolysis activity and reduced plaque size in mouse fibroblast cells. These findings indicate that RsbT and RsbV both contribute to σBactivation inL. monocytogenesduring exposure to environmental and energy stresses as well as during tissue culture infection.
Epiphytic Cyanobacteria onChara vulgarisAre the Main Contributors to N2Fixation in Rice Fields
Authors: Ariosa Yoanna , Quesada Antonio , Aburto Juan , Carrasco David , Carreres Ramón , Leganés Francisco , Fernández Valiente Eduardo 
Published: September 2004

ABSTRACTThe distribution of nitrogenase activity in the rice-soil system and the possible contribution of epiphytic cyanobacteria on rice plants and other macrophytes to this activity were studied in two locations in the rice fields of Valencia, Spain, in two consecutive crop seasons. The largest proportion of photodependent N2fixation was associated with the macrophyteChara vulgarisin both years and at both locations. The nitrogen fixation rate associated withCharaalways represented more than 45% of the global nitrogenase activity measured in the rice field. The estimated average N2fixation rate associated withCharawas 27.53 kg of N ha−1crop−1. The mean estimated N2fixation rates for the other parts of the system for all sampling periods were as follows: soil, 4.07 kg of N ha−1crop−1; submerged parts of rice plants, 3.93 kg of N ha−1crop−1; and roots, 0.28 kg of N ha−1crop−1. Micrographic studies revealed the presence of epiphytic cyanobacteria on the surface ofChara. Three-dimensional reconstructions by confocal scanning laser microscopy revealed no cyanobacterial cells inside theCharastructures. Quantification of epiphytic cyanobacteria by image analysis revealed that cyanobacteria were more abundant in nodes than in internodes (on average, cyanobacteria covered 8.4% ± 4.4% and 6.2% ± 5.0% of the surface area in the nodes and internodes, respectively). Epiphytic cyanobacteria were also quantified by using a fluorometer. This made it possible to discriminate which algal groups were the source of chlorophylla. Chlorophyllameasurements confirmed that cyanobacteria were more abundant in nodes than in internodes (on average, the chlorophyllaconcentrations were 17.2 ± 28.0 and 4.0 ± 3.8 μg mg [dry weight] ofChara−1in the nodes and internodes, respectively). These results indicate that this macrophyte, which is usually considered a weed in the context of rice cultivation, may help maintain soil N fertility in the rice field ecosystem.