bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Growth Phase on Adhesion Kinetics of
Escherichia coli
D21g
Authors: Walker Sharon L. , Hill Jane E. , Redman Jeremy A. , Elimelech Menachem 
Published: June 2005

ABSTRACT

The influence of bacterial growth stage and the evolution of surface macromolecules on cell adhesion have been examined by using a mutant of
Escherichia coli
K-12. To better understand the adhesion kinetics of bacteria in the mid-exponential and stationary growth phases under flow conditions, deposition experiments were conducted in a well-controlled radial stagnation point flow (RSPF) system. Complementary cell characterization techniques were conducted in combination with the RSPF experiments to evaluate the hydrophobicity, electrophoretic mobility, size, and titratable surface charge of the cells in the two growth phases considered. It was observed that cells in stationary phase were notably more adhesive than those in mid-exponential phase. This behavior is attributed to the high degree of local charge heterogeneity on the outer membranes of stationary-phase cells, which results in decreased electrostatic repulsion between the cells and a quartz surface. The mid-exponential-phase cells, on the other hand, have a more uniform charge distribution on the outer membrane, resulting in greater electrostatic repulsion and, subsequently, less adhesion. Our results suggest that the macromolecules responsible for this phenomenon are outer membrane-bound proteins and lipopolysaccharide-associated functional groups.
Inactivation of Enteric Adenovirus and Feline Calicivirus by Chlorine Dioxide
Authors: Thurston-Enriquez Jeanette A. , Haas Charles N. , Jacangelo Joseph , Gerba Charles P. 
Published: June 2005

ABSTRACT

Chlorine dioxide (ClO
2
) inactivation experiments were conducted with adenovirus type 40 (AD40) and feline calicivirus (FCV). Experiments were carried out in buffered, disinfectant demand-free water under high- and low-pH and -temperature conditions.
Ct
values (the concentration of ClO
2
multiplied by contact time with the virus) were calculated directly from bench-scale experiments and from application of the efficiency factor Hom (EFH) model. AD40
Ct
ranges for 4-log inactivation (
Ct
99.99%
) at 5°C were >0.77 to <1.53 mg/liter × min and >0.80 to <1.59 mg/liter × min for pH 6 and 8, respectively. For 15°C AD40 experiments, >0.49 to <0.74 mg/liter × min and <0.12 mg/liter × min
Ct
99.99%
ranges were observed for pH 6 and 8, respectively. FCV
Ct
99.99%
ranges for 5°C experiments were >20.20 to <30.30 mg/liter × min and >0.68 mg/liter × min for pH 6 and 8, respectively. For 15°C FCV experiments,
Ct
99.99%
ranges were >4.20 to <6.72 and <0.18 mg/liter × min for pH 6 and 8, respectively. Viral inactivation was higher at pH 8 than at pH 6 and at 15°C than at 5°C. Comparison of
Ct
values and inactivation curves demonstrated that the EFH model described bench-scale experiment data very well. Observed bench-scale
Ct
99.99%
ranges and EFH model
Ct
99.99%
values demonstrated that FCV is more resistant to ClO
2
than AD40 for the conditions studied. U.S. Environmental Protection Agency guidance manual
Ct
99.99%
values are higher than
Ct
99.99%
values calculated from bench-scale experiments and from EFH model application.
Abundant Respirable Ergot Alkaloids from the Common Airborne Fungus
Aspergillus fumigatus
Authors: Panaccione Daniel G. , Coyle Christine M. 
Published: June 2005

ABSTRACT

Ergot alkaloids are mycotoxins that interact with several monoamine receptors, negatively affecting cardiovascular, nervous, reproductive, and immune systems of exposed humans and animals.
Aspergillus fumigatus
, a common airborne fungus and opportunistic human pathogen, can produce ergot alkaloids in broth culture. The objectives of this study were to determine if
A. fumigatus
accumulates ergot alkaloids in a respirable form in or on its conidia, to quantify ergot alkaloids associated with conidia produced on several different substrates, and to measure relevant physical properties of the conidia. We found at least four ergot alkaloids, fumigaclavine C, festuclavine, fumigaclavine A, and fumigaclavine B (in order of abundance), associated with conidia of
A. fumigatus
. Under environmentally relevant conditions, the total mass of ergot alkaloids often constituted >1% of the mass of the conidium. Ergot alkaloids were extracted from conidia produced on all media tested, and the greatest quantities were observed when the fungus was cultured on latex paint or cultured maize seedlings. The values for physical properties of conidia likely to affect their respirability (i.e., diameter, mass, and specific gravity) were significantly lower for
A. fumigatus
than for
Aspergillus nidulans
,
Aspergillus niger
, and
Stachybotrys chartarum
. The demonstration of relatively high concentrations of ergot alkaloids associated with conidia of
A. fumigatus
presents opportunities for investigations of potential contributions of the toxins to adverse health effects associated with the fungus and to aspects of the biology of the fungus that contribute to its success.
Abundance and Diversity of Viruses in Six Delaware Soils
Authors: Williamson Kurt E. , Radosevich Mark , Wommack K. Eric 
Published: June 2005

ABSTRACT

The importance of viruses in marine microbial ecology has been established over the past decade. Specifically, viruses influence bacterial abundance and community composition through lysis and alter bacterial genetic diversity through transduction and lysogenic conversion. By contrast, the abundance and distribution of viruses in soils are almost completely unknown. This study describes the abundance and diversity of autochthonous viruses in six Delaware soils: two agricultural soils, two coastal plain forest soils, and two piedmont forest soils. Viral abundance was measured using epifluorescence microscopy, while viral diversity was assessed from morphological data obtained through transmission electron microscopy. Extracted soil virus communities were dominated by bacteriophages that demonstrated a wide range of capsid diameters (20 nm to 160 nm) and morphologies, including filamentous forms and phages with elongated capsids. The reciprocal Simpson's index suggests that forest soils harbor more diverse assemblages of viruses, particularly in terms of morphological distribution. Repeated extractions of virus-like particles (VLPs) from soils indicated that the initial round of extraction removes approximately 70% of extractable viruses. Higher VLP abundances were observed in forest soils (1.31 × 10
9
to 4.17 × 10
9
g
−1
dry weight) than in agricultural soils (8.7 × 10
8
to 1.1 × 10
9
g
−1
dry weight). Soil VLP abundance was significantly correlated to moisture content (
r
= 0.988) but not to soil texture. Land use (agricultural or forested) was significantly correlated to both bacterial (
r
= 0.885) and viral (
r
= 0.812) abundances, as were soil organic matter and water content. Thus, land use is a significant factor influencing viral abundance and diversity in soils.
Genomic Islands in theCorynebacterium efficiensGenome
Authors: Zhang Ren , Zhang Chun-Ting 
Published: June 2005

ABSTRACTCorynebacterium efficiensis a gram-positive nonpathogenic bacterium which can grow and produce glutamate at 40°C or above. By using the cumulative GC profile method, we have identified four genomic islands which have many unifying genomic island-specific features in theC. efficiensgenome. The presence of the gene encoding an aspartate kinase in a genomic island helps explain the unexpected low thermal stability of this enzyme; i.e., the adaptive mutations have not occurred extensively due to the recent horizontal gene transfer.
Quantitative Real-Time PCR Assays for Detection of Human Adenoviruses and Identification of Serotypes 40 and 41
Authors: Jothikumar Narayanan , Cromeans Theresa L. , Hill Vincent R. , Lu Xiaoyan , Sobsey Mark D. , Erdman Dean D. 
Published: June 2005

ABSTRACT
A quantitative real-time TaqMan PCR assay for detection of human adenoviruses (HAdV) was developed using broadly reactive consensus primers and a TaqMan probe targeting a conserved region of the hexon gene. The TaqMan assay correctly identified 56 representative adenovirus prototype strains and field isolates from all six adenovirus species (A to F). Based on infectious units, the TaqMan assay was able to detect as few as 0.4 and 0.004 infectious units of adenovirus serotype 2 (AdV2) and AdV41, respectively, with results obtained in less than 90 min. Using genomic equivalents, the broadly reactive TaqMan assay was able to detect 5 copies of AdV40 (which had zero mismatches with the PCR primers and probe), 8 copies of AdV41, and 350 copies of AdV3 (which had the most mismatches [seven] of any adenovirus serotype tested). For specific detection and identification of F species serotypes AdV40 and AdV41, a second real-time PCR assay was developed using fluorescence resonance energy transfer (FRET) probes that target the adenovirus fiber gene. The FRET-based assay had a detection limit of 3 to 5 copies of AdV40 and AdV41 standard DNA and was able to distinguish between AdV40 and AdV41 based on melting curve analysis. Both the TaqMan and FRET PCR assays were quantitative over a wide range of virus titers. Application of these assays for detection of adenoviruses and type-specific identification of AdV40 and AdV41 will be useful for identifying these viruses in environmental and clinical samples.
Continuous-Flow Capillary Assay for Measuring Bacterial Chemotaxis
Authors: Law Aaron M. J. , Aitken Michael D. 
Published: June 2005

ABSTRACT

Bacterial chemotaxis may have a significant impact on the structure and function of bacterial communities. Quantification of chemotactic motion is necessary to identify chemoeffectors and to determine the bacterial transport parameters used in predictive models of chemotaxis. When the chemotactic bacteria consume the chemoeffector, the chemoeffector gradient to which the bacteria respond may be significantly perturbed by the consumption. Therefore, consumption of the chemoeffector can confound chemotaxis measurements if it is not accounted for. Current methods of quantifying chemotaxis use bacterial concentrations that are too high to preclude chemoeffector consumption or involve ill-defined conditions that make quantifying chemotaxis difficult. We developed a method of quantifying bacterial chemotaxis at low cell concentrations (∼10
5
CFU/ml), so metabolism of the chemoeffector is minimized. The method facilitates quantification of bacterial-transport parameters by providing well-defined boundary conditions and can be used with volatile and semivolatile chemoeffectors.
Amplified Intergenic Locus Polymorphism as a Basis for Bacterial Typing of
Listeria
spp. and
Escherichia
coli
Authors: Somer Lilach , Danin-Poleg Yael , Diamant Eran , Gur-Arie Riva , Palti Yniv , Kashi Yechezkel 
Published: June 2005

ABSTRACT

DNA-based methods are increasingly important for bacterial typing. The high number of polymorphic sites present among closely related bacterial genomes is the basis for the presented method. The method identifies multilocus genomic polymorphisms in intergenic regions termed AILP (amplified intergenic locus polymorphism). For each locus, a pair of unique PCR primers was designed to amplify an intergenic sequence from one open reading frame (ORF) to the adjacent ORF. Presence, absence, and size variation of the amplification products were identified and used as genetic markers for rapidly differentiating among strains. Polymorphism was evaluated using 18 AILP sites among 28 strains of
Listeria
monocytogenes
and 6 strains of
Listeria
spp. and 30 AILP markers among 27 strains of
Escherichia
coli
. Up to four alleles per locus were identified among
Listeria
strains, and up to six were identified among
E. coli
strains. In both species, more than half of the AILP sites revealed intraspecies polymorphism. The AILP data were applied to phylogenetic analysis among
Listeria
and
E. coli
strains. A clear distinction between
L. monocytogenes
and
Listeria
spp. was demonstrated. In addition, the method separated
L. monocytogenes
into the three known lineages and discriminated the most common virulent serotypic group, 4b. In
E. coli
, AILP analysis separated the known groups as well as the virulent O157:H7 isolates. These findings for both
Listeria
and
E. coli
are in agreement with other phylogenetic studies using molecular markers. The AILP method was found to be rapid, simple, reproducible, and a low-cost method for initial bacterial typing that could serve as a basis for epidemiological investigation.
First Detection and Genotyping of Human-Associated Microsporidia in Pigeons from Urban Parks
Authors: Haro M. , Izquierdo F. , Henriques-Gil N. , Andrés I. , Alonso F. , Fenoy S. , del Águila C. 
Published: June 2005

ABSTRACTMicrosporidia are ubiquitous opportunistic parasites in nature infecting all animal phyla, and the zoonotic potential of this parasitosis is under discussion. Fecal samples from 124 pigeons from seven parks of Murcia (Spain) were analyzed. Thirty-six of them (29.0%) showed structures compatible with microsporidia spores by staining methods. The DNA isolated from 26 fecal samples (20.9%) of microsporidia-positive pigeons was amplified with specific primers for the four most frequent human microsporidia. Twelve pigeons were positive for onlyEnterocytozoon bieneusi(9.7%), 5 forEncephalitozoon intestinalis(4%), and one forEncephalitozoon hellem(0.8%). Coinfections were detected in eight additional pigeons:E. bieneusiandE. hellemwere detected in six animals (4.8%);E. bieneusiwas associated withE. intestinalisin one case (0.8%); andE. hellemandE. intestinaliscoexisted in one pigeon. No positive samples forEncephalitozoon cuniculiwere detected. The internally transcribed spacer genotype could be completed for oneE. hellem-positive pigeon; the result was identical to the genotype A1 previously characterized in anE. hellemSpanish strain of human origin. To our knowledge, this is the first time that human-related microsporidia have been identified in urban park pigeons. Moreover, we can conclude that there is no barrier to microsporidia transmission between park pigeons and humans forE. intestinalisandE. hellem. This study is of environmental and sanitary interest, because children and elderly people constitute the main visitors of parks and they are populations at risk for microsporidiosis. It should also contribute to the better design of appropriate prophylactic measures for populations at risk for opportunistic infections.
Novel Putative Galactose Operon Involving Lacto-N-Biose Phosphorylase inBifidobacterium longum
Authors: Kitaoka Motomitsu , Tian Jiesheng , Nishimoto Mamoru 
Published: June 2005

ABSTRACTA lacto-N-biose phosphorylase (LNBP) was purified from the cell extract ofBifidobacterium bifidum. Its N-terminal and internal amino acid sequences were homologous with those of the hypothetical protein ofBifidobacterium longumNCC2705 encoded by the BL1641 gene. The homologous gene of the type strainB. longumJCM1217,lnpA, was expressed inEscherichia colito confirm that it encoded LNBP. No significant identity was found with any proteins with known function, indicating that LNBP should be classified in a new family. ThelnpAgene is located in a novel putative operon for galactose metabolism that does not contain a galactokinase gene. The operon seems to be involved in intestinal colonization by bifidobacteria mediated by metabolism of mucin sugars. In addition, it may also resolve the question of the nature of the bifidus factor in human milk as the lacto-N-biose structure found in milk oligosaccharides.
Validity of the Indicator Organism Paradigm for Pathogen Reduction in Reclaimed Water and Public Health Protection
Authors: Harwood Valerie J. , Levine Audrey D. , Scott Troy M. , Chivukula Vasanta , Lukasik Jerzy , Farrah Samuel R. , Rose Joan B. 
Published: June 2005

ABSTRACT

The validity of using indicator organisms (total and fecal coliforms, enterococci,
Clostridium perfringens
, and F-specific coliphages) to predict the presence or absence of pathogens (infectious enteric viruses,
Cryptosporidium
, and
Giardia
) was tested at six wastewater reclamation facilities. Multiple samplings conducted at each facility over a 1-year period. Larger sample volumes for indicators (0.2 to 0.4 liters) and pathogens (30 to 100 liters) resulted in more sensitive detection limits than are typical of routine monitoring. Microorganisms were detected in disinfected effluent samples at the following frequencies: total coliforms, 63%; fecal coliforms, 27%; enterococci, 27%;
C. perfringens
, 61%; F-specific coliphages, ∼40%; and enteric viruses, 31%.
Cryptosporidium
oocysts and
Giardia
cysts were detected in 70% and 80%, respectively, of reclaimed water samples. Viable
Cryptosporidium
, based on cell culture infectivity assays, was detected in 20% of the reclaimed water samples. No strong correlation was found for any indicator-pathogen combination. When data for all indicators were tested using discriminant analysis, the presence/absence patterns for
Giardia
cysts,
Cryptosporidium
oocysts, infectious
Cryptosporidium
, and infectious enteric viruses were predicted for over 71% of disinfected effluents. The failure of measurements of single indicator organism to correlate with pathogens suggests that public health is not adequately protected by simple monitoring schemes based on detection of a single indicator, particularly at the detection limits routinely employed. Monitoring a suite of indicator organisms in reclaimed effluent is more likely to be predictive of the presence of certain pathogens, and a need for additional pathogen monitoring in reclaimed water in order to protect public health is suggested by this study.
Movement and Fixation of Intestinal Microbiota after Administration of Human Feces to Germfree Mice
Authors: Kibe Ryoko , Sakamoto Mitsuo , Yokota Hiroshi , Ishikawa Hiroki , Aiba Yuji , Koga Yasuhiro , Benno Yoshimi 
Published: June 2005

ABSTRACT

Human flora-associated (HFA) mice have been considered a tool for studying the ecology and metabolism of intestinal bacteria in humans, although they have some limitations as a model. Shifts in dominant species of microbiota in HFA mice after the administration of human intestinal microbiota was revealed by 16S rRNA gene sequence and terminal restriction fragment length polymorphism (T-RFLP) analyses. Characteristic terminal restriction fragments (T-RFs) were quantified as the proportion of total peak area of all T-RFs. Only the proportion of the T-RF peak at bp 366, identified as the
Gammmaproteobacteria
group and the family
Coriobacteriaceae
, was reduced in this study. Increased T-RFs over time at bp 56, 184, and 196 were affiliated with the
Clostridium
group. However, most of the isolated bacteria with unique population shifts were phylotypes. The vertical transmission of the intestinal microbiota of the mouse offspring was also investigated by dendrogram analysis derived from the similarity of T-RFLP patterns among samples. As a result, the intestinal microbiota of HFA mice and their offspring reflected the composition of individual human intestinal bacteria with some modifications. Moreover, we revealed that human-derived lactobacilli (HDL), which have been considered difficult to colonize in the HFA mouse intestine in previous studies based on culture methods, could be detected in the HFA mouse intestine by using a lactic acid bacterium-specific primer and HDL-specific primers. Our results indicate that the intestinal microbiota of HFA mice represents a limited sample of bacteria from the human source and are selected by unknown interactions between the host and bacteria.
Microplate Subtractive Hybridization To Enrich for
Bacteroidales
Genetic Markers for Fecal Source Identification
Authors: Dick Linda K. , Simonich Michael T. , Field Katharine G. 
Published: June 2005

ABSTRACT

The ability to identify sources of fecal pollution plays a key role in the analysis of human health risk and the implementation of water resource management strategies. One approach to this problem involves the identification of bacterial lineages or gene sequences that are found exclusively in a particular host species or group. We used subtractive hybridization to enrich for target host-specific fecal
Bacteroidales
rRNA gene fragments that were different from those of very closely related reference (subtracter) host sources. Target host rRNA gene fragments were hybridized to subtracter rRNA gene fragments immobilized in a microplate well, and target sequences that did not hybridize were cloned and sequenced for PCR primer design. The use of microplates for DNA immobilization resulted in a one-step subtractive hybridization in which the products could be directly amplified with PCR. The new host-specific primers designed from subtracted target fragments differentiated among very closely related
Bacteroidales
rRNA gene sequences and distinguished between similar fecal sources, such as elk and cow or human and domestic pet (dog).
Characterization of
Wolbachia
Transfection Efficiency by Using Microinjection of Embryonic Cytoplasm and Embryo Homogenate
Authors: Xi Zhiyong , Dobson Stephen L. 
Published: June 2005

ABSTRACT

Wolbachia
spp. are intracellular alpha proteobacteria closely related to
Rickettsia
. The maternally inherited infections occur in a wide range of invertebrates, causing several reproductive abnormalities, including cytoplasmic incompatibility. The artificial transfer of
Wolbachia
between hosts (transfection) is used both for basic research examining the
Wolbachia
-host interaction and for applied strategies that use
Wolbachia
infections to affect harmful insect populations. Commonly employed transfection techniques use embryonic microinjection to transfer
Wolbachia
-infected embryo cytoplasm or embryo homogenate. Although microinjections of both embryonic cytoplasm and homogenate have been used successfully, their respective transfection efficiencies (rates of establishing stable germ line infections) have not been directly compared. Transfection efficiency may be affected by variation in
Wolbachia
quantity or quality within the donor embryos and/or the buffer types used in embryo homogenization. Here we have compared
Wolbachia
bacteria that originate from different embryonic regions for their competencies in establishing stable germ line infections. The following three buffers were compared for their abilities to maintain an appropriate in vitro environment for
Wolbachia
during homogenization and injection: phosphate-buffered saline,
Drosophila
Ringer's buffer, and a sucrose-phosphate-glutamate solution (SPG buffer). The results demonstrate that
Wolbachia
bacteria from both anterior and posterior embryo cytoplasms are competent for establishing infection, although differing survivorships of injected hosts were observed. Buffer comparison shows that embryos homogenized in SPG buffer yielded the highest transfection success. No difference was observed in transfection efficiencies when the posterior cytoplasm transfer and SPG-homogenized embryo techniques were compared. We discuss the results in relation to intra- and interspecific
Wolbachia
transfection and the future adaptation of the microinjection technique for additional insects.