bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microscopic Examination of Distribution and Phenotypic Properties of Phylogenetically Diverse
Chloroflexaceae
-Related Bacteria in Hot Spring Microbial Mats
Authors: Nübel Ulrich , Bateson Mary M. , Vandieken Verona , Wieland Andrea , Kühl Michael , Ward David M. 
Published: August 2002

ABSTRACT

We investigated the diversity, distribution, and phenotypes of uncultivated
Chloroflexaceae
-related bacteria in photosynthetic microbial mats of an alkaline hot spring (Mushroom Spring, Yellowstone National Park). By applying a directed PCR approach, molecular cloning, and sequence analysis of 16S rRNA genes, an unexpectedly large phylogenetic diversity among these bacteria was detected. Oligonucleotide probes were designed to target 16S rRNAs from organisms affiliated with the genus
Chloroflexus
or with the type C cluster, a group of previously discovered
Chloroflexaceae
relatives of this mat community. The application of peroxidase-labeled probes in conjunction with tyramide signal amplification enabled the identification of these organisms within the microbial mats by fluorescence in situ hybridization (FISH) and the investigation of their morphology, abundance, and small-scale distribution. FISH was combined with oxygen microelectrode measurements, microscope spectrometry, and microautoradiography to examine their microenvironment, pigmentation, and carbon source usage. Abundant type C-related, filamentous bacteria were found to flourish within the cyanobacterium-dominated, highly oxygenated top layers and to predominate numerically in deeper orange-colored zones of the investigated microbial mats, correlating with the distribution of bacteriochlorophyll
a. Chloroflexus
sp. filaments were rare at 60°C but were more abundant at 70°C, where they were confined to the upper millimeter of the mat. Both type C organisms and
Chloroflexus
spp. were observed to assimilate radiolabeled acetate under in situ conditions.
Construction and Characterization of a
proU
-
gfp
Transcriptional Fusion That Measures Water Availability in a Microbial Habitat
Authors: Axtell Catherine A. , Beattie Gwyn A. 
Published: August 2002

ABSTRACT

We constructed and characterized a transcriptional fusion that measures the availability of water to a bacterial cell. This fusion between the
proU
promoter from
Escherichia coli
and the reporter gene
gfp
was introduced into strains of
E. coli
,
Pantoea agglomerans
, and
Pseudomonas syringae
. The
proU
-
gfp
fusion in these bacterial biosensor strains responded in a quantitative manner to water deprivation caused by the presence of NaCl, Na
2
SO
4
, KCl, or polyethylene glycol (molecular weight, 8000). The fusion was induced to a detectable level by NaCl concentrations of as low as 10 mM in all three bacterial species. Water deprivation induced
proU
-
gfp
expression in both planktonic and surface-associated cells; however, it induced a higher level of expression in the surface-associated cells. Following the introduction of
P. agglomerans
biosensor cells onto bean leaves, the cells detected a significant decrease in water availability within only 5 min. After 30 min, the populations were exposed, on average, to a water potential equivalent to that imposed by approximately 55 mM NaCl. These results demonstrate the effectiveness of a
proU
-
gfp
-based biosensor for evaluating water availability on leaves. Furthermore, the inducibility of
proU
-
gfp
in multiple bacterial species illustrates the potential for tailoring
proU
-
gfp
-based biosensors to specific habitats.
Isolation of Tellurite- and Selenite-Resistant Bacteria from Hydrothermal Vents of the Juan de Fuca Ridge in the Pacific Ocean
Authors: Rathgeber Christopher , Yurkova Natalia , Stackebrandt Erko , Beatty J. Thomas , Yurkov Vladimir 
Published: August 2002

ABSTRACT

Deep-ocean hydrothermal-vent environments are rich in heavy metals and metalloids and present excellent sites for the isolation of metal-resistant microorganisms. Both metalloid-oxide-resistant and metalloid-oxide-reducing bacteria were found. Tellurite- and selenite-reducing strains were isolated in high numbers from ocean water near hydrothermal vents, bacterial films, and sulfide-rich rocks. Growth of these isolates in media containing K
2
TeO
3
or Na
2
SeO
3
resulted in the accumulation of metallic tellurium or selenium. The MIC of K
2
TeO
3
ranged from 1,500 to greater than 2,500 μg/ml, and the MIC of Na
2
SeO
3
ranged from 6,000 to greater than 7,000 μg/ml for 10 strains. Phylogenetic analysis of 4 of these 10 strains revealed that they form a branch closely related to members of the genus
Pseudoalteromonas
, within the γ-3 subclass of the
Proteobacteria
. All 10 strains were found to be salt tolerant, pH tolerant, and thermotolerant. The metalloid resistance and morphological, physiological, and phylogenetic characteristics of newly isolated strains are described.
Aquatic Insects as a Vector for
Mycobacterium ulcerans
Authors: Marsollier Laurent , Robert Raymond , Aubry Jacques , Saint André Jean-Paul , Kouakou Henri , Legras Pierre , Manceau Anne-Lise , Mahaza Chetaou , Carbonnelle Bernard 
Published: August 2002

ABSTRACT

Mycobacterium ulcerans
is an emerging environmental pathogen which causes chronic skin ulcers (i.e., Buruli ulcer) in otherwise healthy humans living in tropical countries, particularly those in Africa. In spite of epidemiological and PCR data linking
M. ulcerans
to water, the mode of transmission of this organism remains elusive. To determine the role of aquatic insects in the transmission of
M. ulcerans
, we have set up an experimental model with aquariums that mimic aquatic microenvironments. We report that
M. ulcerans
may be transmitted to laboratory mice by the bite of aquatic bugs (Naucoridae) that are infected with this organism. In addition,
M. ulcerans
appears to be localized exclusively within salivary glands of these insects, where it can both survive and multiply without causing any observable damage in the insect tissues. Subsequently, we isolated
M. ulcerans
from wild aquatic insects collected from a zone in the Daloa region of Ivory Coast where Buruli ulcer is endemic. Taken together, these results point to aquatic insects as a possible vector of
M. ulcerans
.
Abundance and Phylogenetic Affiliation of Iron Reducers in Activated Sludge as Assessed by Fluorescence In Situ Hybridization and Microautoradiography
Authors: Nielsen Jeppe Lund , Juretschko Stefan , Wagner Michael , Nielsen Per Halkjær 
Published: August 2002

ABSTRACT

Microautoradiography (MAR) was used to enumerate acetate-consuming bacteria under Fe(III)-reducing conditions in activated sludge. This population is believed to consist of dissimilatory iron-reducing bacteria, because the applied incubation conditions and the use of specific inhibitors excluded consumption of radiolabeled acetate by other physiological groups such as sulfate reducers. By use of this approach, dissimilatory iron reducers were found in a concentration of 1.1 × 10
8
cells per ml, corresponding to approximately 3% of the total cell count as determined by DAPI (4′,6′-diamino-2-phenylindoledihydrochloride-dilactate) staining. The MAR enumeration method was compared to the traditional most-probable-number (MPN) method (FeOOH-MPN) and a modified MPN method, which contains Ferrozine directly within the MPN dilutions to determine the production of small amounts of ferrous iron (Ferrozine-MPN). The Ferrozine-MPN method yielded values 6 to 10 times higher than those obtained by the FeOOH-MPN method. Nevertheless, the MAR approach yielded counts that were 100 to 1,000 times higher than those obtained by the Ferrozine-MPN method. Specific in situ Fe(III) reduction rates per cell (enumerated by the MAR method) were calculated and found to be comparable to the respective rates for pure cultures of dissimilatory iron-reducing bacteria, suggesting that the new MAR method is most reliable. A combination of MAR and fluorescence in situ hybridization was used for phylogenetic characterization of the putative iron-reducing bacteria. All activated-sludge cells able to consume acetate under iron-reducing conditions were targeted by the bacterial oligonucleotide probe EUB338. Around 20% were identified as gamma
Proteobacteria
, and 10% were assigned to the delta subclass of
Proteobacteria
.
Endosymbiotic Bacteria in the Esophageal Organ of Glossiphoniid Leeches
Authors: Kikuchi Yoshitomo , Fukatsu Takema 
Published: August 2002

ABSTRACT

We characterized the intracellular symbiotic bacteria of the hematophagous glossiphoniid leeches
Placobdelloides siamensis
and a
Parabdella
sp. These leeches have a specialized structure called an “esophageal organ,” the cells of which harbor bacterial symbionts. From the esophageal organ of each species, a 1.5-kb eubacterial 16S rRNA gene segment was amplified by PCR, cloned, and sequenced. Diagnostic PCR detected the symbiont in the esophageal organ and intestine. Phylogenetic analysis of the 16S rRNA gene(s) demonstrated that the symbionts from the leeches formed a monophyletic group in a well-defined clade containing endosymbiotic bacteria of plant sap-feeding insects in the γ-subdivision of the
Proteobacteria
. The nucleotide compositions of the 16S rRNA gene from the leech symbionts were highly AT biased (53.7%).
Effect of
Weissella confusa
Strain PL9001 on the Adherence and Growth of
Helicobacter pylori
Authors: Nam Hyeran , Ha Misun , Bae On , Lee Yeonhee 
Published: August 2002

ABSTRACT

Viable and nonviable
Weissella confusa
strain PL9001 inhibited the binding of
Helicobacter pylori
to human gastric-cell line MKN-45 cells by more than 90%. Spent culture supernatant of PL9001 rapidly decreased the viability of
H. pylori
, rupturing cell walls. The results suggest that PL9001 is a probiotic that can reduce the infectivity and persistence of
H. pylori
.
Infection of Mice with Aerosolized
Mycobacterium tuberculosis
: Use of a Nose-Only Apparatus for Delivery of Low Doses of Inocula and Design of an Ultrasafe Facility
Authors: Schwebach J. Reid , Chen Bing , Glatman-Freedman Aharona , Casadevall Arturo , McKinney John D. , Harb John L. , McGuire Patrick J. , Barkley W. Emmett , Bloom Barry R. , Jacobs William R. 
Published: August 2002

ABSTRACT

Aerosolized delivery of virulent or hypervirulent
Mycobacterium tuberculosis
requires careful consideration of methodology and safety. To maximize safety, we installed a nose-only aerosol apparatus that can reproducibly deliver a low dose (<100 CFU per mouse) of
M. tuberculosis
in a carefully designed biohazard facility.
Potential for Misidentification of a Spore-Forming
Paenibacillus polymyxa
Isolate as an Endophyte by Using Culture-Based Methods
Authors: Bent Elizabeth , Chanway Christopher P. 
Published: August 2002

ABSTRACT

While
Paenibacillus polymyxa
strain Pw-2 has been identified as an endophyte of lodgepole pine (M. Shishido, B. M. Loeb, and C. P. Chanway, Can. J. Microbiol. 41:707-713, 1995),
P. polymyxa
strain L6 has not, a distinction that could be explained by the differential abilities of these isolates to form spores, rather than the differential abilities to colonize the interior tissues of lodgepole pine. Chemical disinfection was used to destroy bacteria on the root exterior, but bacterial endospores are known for their ability to withstand chemical disinfection, and strain Pw-2 was found to produce 300 to 11,000 times more germinating endospores than strain L6 under the experimental conditions used by Shishido et al. (Can. J. Microbiol. 41:707-713, 1995). Attempts to identify strain Pw-2 within lodgepole pine root tissues by using confocal microscopy techniques failed. We discuss the possibility that spore-forming bacteria can be mistakenly identified as endophytes when culture-based methods alone are used.
Characterization of the Lipopolysaccharides and Capsules of
Shewanella
spp
Authors: Korenevsky Anton A. , Vinogradov Evgeny , Gorby Yuri , Beveridge Terry J. 
Published: August 2002

ABSTRACT

Electron microscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis with silver staining and
1
H,
13
C, and
31
P-nuclear magnetic resonance (NMR) were used to detect and characterize the lipopolysaccharides (LPSs) of several
Shewanella
species. Many expressed only rough LPS; however, approximately one-half produced smooth LPS (and/or capsular polysaccharides). Some LPSs were affected by growth temperature with increased chain length observed below 25°C. Maximum LPS heterogeneity was found at 15 to 20°C. Thin sections of freeze-substituted cells revealed that
Shewanella oneidensis
,
S. algae
,
S. frigidimarina
, and
Shewanella
sp. strain MR-4 possessed either O-side chains or capsular fringes ranging from 20 to 130 nm in thickness depending on the species. NMR detected unusual sugars in
S. putrefaciens
CN32 and
S. algae
BrY
DL
. It is possible that the ability of
Shewanella
to adhere to solid mineral phases (such as iron oxides) could be affected by the composition and length of surface polysaccharide polymers. These same polymers in
S. algae
may also contribute to this opportunistic pathogen's ability to promote infection.
Gene Disruption by Homologous Recombination in the
Xylella fastidiosa
Citrus Variegated Chlorosis Strain
Authors: Gaurivaud Patrice , Souza Leonardo C. A. , Virgílio Andrea C. D. , Mariano Anelise G. , Palma Renê R. , Monteiro Patrícia B. 
Published: August 2002

ABSTRACT

Mutagenesis by homologous recombination was evaluated in
Xylella fastidiosa
by using the
bga
gene, coding for β-galactosidase, as a model. Integration of replicative plasmids by homologous recombination between the cloned truncated copy of
bga
and the endogenous gene was produced by one or two crossover events leading to β-galactosidase mutants. A promoterless chloramphenicol acetyltransferase gene was used to monitor the expression of the target gene and to select a
cvaB
mutant.
Quorum Sensing and Production of Autoinducer-2 in
Campylobacter
spp.,
Escherichia coli
O157:H7, and
Salmonella enterica
Serovar Typhimurium in Foods
Authors: Cloak Orla M. , Solow Barbara T. , Briggs Connie E. , Chen Chin-Yi , Fratamico Pina M. 
Published: August 2002

ABSTRACT

Autoinducer molecules are utilized by gram-negative and gram-positive bacteria to regulate density-dependent gene expression by a mechanism known as quorum sensing. PCR and DNA sequencing results showed that
Campylobacter jejuni
and
Campylobacter coli
possessed
luxS
, which is responsible for autoinducer-2 (AI-2) production. Using a
Vibrio harveyi
luminescence assay, the production of AI-2 was observed in milk, chicken broth, and brucella broth by
C. coli
,
C. jejuni
,
Salmonella enterica
serovar Typhimurium, and
Escherichia coli
O157:H7 under different conditions.
Enzymatic Degradation of Chlorodiamino-
s
-Triazine
Authors: Seffernick Jennifer L. , Shapir Nir , Schoeb Michael , Johnson Gilbert , Sadowsky Michael J. , Wackett Lawrence P. 
Published: August 2002

ABSTRACT

2-Chloro-4,6-diamino-
s
-triazine (CAAT) is a metabolite of atrazine biodegradation in soils. Atrazine chlorohydrolase (AtzA) catalyzes the dechlorination of atrazine but is unreactive with CAAT. In this study, melamine deaminase (TriA), which is 98% identical to AtzA, catalyzed deamination of CAAT to produce 2-chloro-4-amino-6-hydroxy-
s
-triazine (CAOT). CAOT underwent dechlorination via hydroxyatrazine ethylaminohydrolase (AtzB) to yield ammelide. This represents a newly discovered dechlorination reaction for AtzB. Ammelide was subsequently hydrolyzed by
N
-isopropylammelide isopropylaminohydrolase to produce cyanuric acid, a compound metabolized by a variety of soil bacteria.
Escherichia coli
O157 and Non-O157 Isolates Are More Susceptible to
l
-Lactate than to
d
-Lactate
Authors: McWilliam Leitch E. C. , Stewart C. S. 
Published: August 2002

ABSTRACT

The antimicrobial effect of
l
-lactate was much greater than that of
d
-lactate over a range of concentrations for
Escherichia coli
O157 and non-O157 strains. Despite this, the intracellular pHs and membrane potentials of
l
-lactate- and
d
-lactate-treated cells were similar, suggesting that these factors are not involved in the antimicrobial action of
l
-lactate.
Comparison of Models Describing Light Dependence of N2Fixation in Heterocystous Cyanobacteria
Authors: Staal Marc , te Lintel Hekkert Sacco , Herman Peter , Stal Lucas J. 
Published: August 2002

ABSTRACTThe abilities of four models to describe nitrogenase light-response curves were compared, using the heterocystous cyanobacteriumNodularia spumigenaand a cyanobacterial bloom from the Baltic Sea as examples. All tested models gave a good fit of the data, and the rectangular hyperbola model is recommended for fitting nitrogenase-light response curves. This model describes an enzymatic process, while the others are empirical. It was possible to convert the process parameters between the four models and compare N2fixation with photosynthesis. The physiological meanings of the process parameters are discussed and compared to those of photosynthesis.
Enhanced Degradation of an Endocrine-Disrupting Chemical, Butyl Benzyl Phthalate, byFusarium oxysporumf. sp.pisiCutinase
Authors: Kim Yang-Hoon , Lee Jeewon , Ahn Ji-Young , Gu Man Bock , Moon Seung-Hyeon 
Published: August 2002

ABSTRACTCompared to yeast esterase, fungal cutinase degraded butyl benzyl phthalate (BBP) far more efficiently; i.e., almost 60% of the BBP disappeared within 7.5 h. Also, the final chemical composition significantly depended on the enzyme used. Toxicity monitoring using bioluminescent bacteria showed that butyl methyl phthalate, a major product of degradation by esterase, was an oxidative toxic hazard.
Cholesterol Assimilation by Lactic Acid Bacteria and Bifidobacteria Isolated from the Human Gut
Authors: Pereira Dora I. A. , Gibson Glenn R. 
Published: August 2002

ABSTRACT

The objective of this study was to evaluate the effect of human gut-derived lactic acid bacteria and bifidobacteria on cholesterol levels in vitro. Continuous cultures inoculated with fecal material from healthy human volunteers with media supplemented with cholesterol and bile acids were used to enrich for potential cholesterol assimilators among the indigenous bacterial populations. Seven potential probiotics were found:
Lactobacillus fermentum
strains F53 and KC5b,
Bifidobacterium infantis
ATCC 15697,
Streptococcus bovis
ATCC 43143,
Enterococcus durans
DSM 20633,
Enterococcus gallinarum
, and
Enterococcus faecalis
. A comparative evaluation regarding the in vitro cholesterol reduction abilities of these strains along with commercial probiotics was undertaken. The degree of acid and bile tolerance of strains was also evaluated. The human isolate
L. fermentum
KC5b was able to maintain viability for 2 h at pH 2 and to grow in a medium with 4,000 mg of bile acids per liter. This strain was also able to remove a maximum of 14.8 mg of cholesterol per g (dry weight) of cells from the culture medium and therefore was regarded as a candidate probiotic.
Diversity of
Sinorhizobium meliloti
from the Central Asian Alfalfa Gene Center
Authors: Roumiantseva Marina L. , Andronov Evgeny E. , Sharypova Larissa A. , Dammann-Kalinowski Tatjana , Keller Mathias , Young J. Peter W. , Simarov Boris V. 
Published: August 2002

ABSTRACT

Sinorhizobium meliloti
was isolated from nodules and soil from western Tajikistan, a center of diversity of the host plants (
Medicago
,
Melilotus
, and
Trigonella
species). There was evidence of recombination, but significant disequilibrium, between and within the chromosome and megaplasmids. The most frequent alleles matched those in the published genome sequence.
Comparison between the Skin Snip Test and Simple Dot Blot Assay as Potential Rapid Assessment Tools for Onchocerciasis in the Postcontrol Era in Ghana
Authors: Guzmán G. E. , Awadzi K. , Opoku N. , Narayanan R. B. , Akuffo H. O. 
Published: August 2002

ABSTRACTSuccessful control of onchocerciasis through mass distribution of ivermectin needs to be coupled with reliable, sensitive, specific, yet affordable diagnostic methods to monitor and ensure the efficacy of such measures. The effort put into the development of diagnostic methods for onchocerciasis that can substitute for or work in combination with the present “gold standard,” the skin snip test, has resulted in the discovery of a number of immunogenic proteins with potential use as diagnostic tools in the postcontrol era. Most of these proteins have now been produced through recombinant DNA techniques. However, when costs are not a trivial issue, none of them have yet found their way into the areas where the disease still exists. In the present study, we have evaluated the performance of a simple dot blot assay which uses a mixture of native proteins designated PakF as a serious contender in the quest for a less invasive and more sensitive method to detectOnchocerca volvulusinfection in areas with diverse endemicities. Our results indicate that the assay we propose is more sensitive than the skin snip test and shows high specificity, both characteristics required for a suitable tool for the monitoring of onchocerciasis in the postcontrol era.
Calcium Phosphate Nanoparticles Induce Mucosal Immunity and Protection against Herpes Simplex Virus Type 2
Authors: He Qing , Mitchell Alaina , Morcol Tulin , Bell Steve J. D. 
Published: August 2002

ABSTRACTPreviously we reported that calcium phosphate nanoparticles (CAP) represented a superior alternative to alum adjuvants in mice immunized with viral protein. Additionally, we showed that CAP was safe and elicited no detectable immunoglobulin E (IgE) response. In this study, we demonstrated that following mucosal delivery of herpes simplex virus type 2 (HSV-2) antigen with CAP, CAP adjuvant enhanced protective systemic and mucosal immunity versus live virus. Mice were immunized intravaginally and intranasally with HSV-2 protein plus CAP adjuvant (HSV-2+CAP), CAP alone, phosphate-buffered saline, or HSV-2 alone. HSV-2+CAP induced HSV-specific mucosal IgA and IgG and concurrently enhanced systemic IgG responses. Our results demonstrate the potency of CAP as a mucosal adjuvant. Furthermore, we show that systemic immunity could be induced via the mucosal route following inoculation with CAP-based vaccine. Moreover, neutralizing antibodies were found in the sera of mice immunized intranasally or intravaginally with HSV-2+CAP. Also, the results of our in vivo experiments indicated that mice vaccinated with HSV-2+CAP were protected against live HSV-2 infection. In conclusion, these preclinical data support the hypothesis that CAP may be an effective mucosal adjuvant that protects against viral infection.