bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Enterocoliticin, a Phage Tail-Like Bacteriocin, and Its Effect on Pathogenic
Yersinia enterocolitica
Strains
Authors: Strauch Eckhard , Kaspar Heike , Schaudinn Christoph , Dersch Petra , Madela Kazimierz , Gewinner Christina , Hertwig Stefan , Wecke Jörg , Appel Bernd 
Published: July 2002

ABSTRACT

Yersinia enterocolitica
29930 (biogroup 1A; serogroup O:7,8) produces a bacteriocin, designated enterocoliticin, that shows inhibitory activity against enteropathogenic strains of
Y. enterocolitica
belonging to serogroups O:3, O:5,27 and O:9. Enterocoliticin was purified, and electron micrographs of enterocoliticin preparations revealed the presence of phage tail-like particles. The particles did not contain nucleic acids and showed contraction upon contact with susceptible bacteria. Enterocoliticin addition to logarithmic-phase cultures of susceptible bacterial strains led to a rapid dose-dependent reduction in CFU. Calorimetric measurements of the heat output of cultures of sensitive bacteria showed a complete loss of cellular metabolic activity immediately upon addition of enterocoliticin. Furthermore, a dose-dependent efflux of K
+
ions into the medium was determined, indicating that enterocoliticin has channel-forming activity.
Reductive, Coenzyme A-Mediated Pathway for 3-Chlorobenzoate Degradation in the Phototrophic Bacterium
Rhodopseudomonas palustris
Authors: Egland Paul G. , Gibson Jane , Harwood Caroline S. 
Published: July 2002

ABSTRACT

We isolated a strain of
Rhodopseudomonas palustris
(RCB100) by selective enrichment in light on 3-chlorobenzoate to investigate the steps that it uses to accomplish anaerobic dechlorination. Analyses of metabolite pools as well as enzyme assays suggest that
R. palustris
grows on 3-chlorobenzoate by (i) converting it to 3-chlorobenzoyl coenzyme A (3-chlorobenzoyl–CoA), (ii) reductively dehalogenating 3-chlorobenzoyl–CoA to benzoyl-CoA, and (iii) degrading benzoyl-CoA to acetyl-CoA and carbon dioxide.
R. palustris
uses 3-chlorobenzoate only as a carbon source and thus incorporates the acetyl-CoA that is produced into cell material. The reductive dechlorination route used by
R. palustris
for 3-chlorobenzoate degradation differs from those previously described in that a CoA thioester, rather than an unmodified aromatic acid, is the substrate for complete dehalogenation.
Novel α-Amylase That Is Highly Resistant to Chelating Reagents and Chemical Oxidants from the Alkaliphilic
Bacillus
Isolate KSM-K38
Authors: Hagihara Hiroshi , Igarashi Kazuaki , Hayashi Yasuhiro , Endo Keiji , Ikawa-Kitayama Kaori , Ozaki Katsuya , Kawai Shuji , Ito Susumu 
Published: July 2002

ABSTRACT

A novel α-amylase (AmyK38) was found in cultures of an alkaliphilic
Bacillus
isolate designated KSM-K38. Based on the morphological and physiological characteristics and phylogenetic position as determined by 16S ribosomal DNA gene sequencing and DNA-DNA reassociation analysis, it was suggested that the isolate was a new species of the genus
Bacillus
. The enzyme had an optimal pH of 8.0 to 9.5 and displayed maximum catalytic activity at 55 to 60°C. The apparent molecular mass was approximately 55 kDa, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the isoelectric point was around pH 4.2. This enzyme efficiently hydrolyzed various carbohydrates to yield maltotriose, maltohexaose, maltoheptaose, and, in addition, maltose as major end products after completion of the reaction. The activity was not prevented at all by EDTA and EGTA at concentrations as high as 100 mM. Moreover, AmyK38 was highly resistant to chemical oxidation and maintained more than 80% of its original activity even after incubation for 1 h in the presence of excess H
2
O
2
(1.8 M).
Impact of Biocontrol
Pseudomonas fluorescens
CHA0 and a Genetically Modified Derivative on the Diversity of Culturable Fungi in the Cucumber Rhizosphere
Authors: Girlanda M. , Perotto S. , Moenne-Loccoz Y. , Bergero R. , Lazzari A. , Defago G. , Bonfante P. , Luppi A. M. 
Published: July 2002

ABSTRACT

Little is known about the effects of
Pseudomonas
biocontrol inoculants on nontarget rhizosphere fungi. This issue was addressed using the biocontrol agent
Pseudomonas fluorescens
CHA0-Rif, which produces the antimicrobial polyketides 2,4-diacetylphloroglucinol (Phl) and pyoluteorin (Plt) and protects cucumber from several fungal pathogens, including
Pythium
spp., as well as the genetically modified derivative CHA0-Rif(pME3424). Strain CHA0-Rif(pME3424) overproduces Phl and Plt and displays improved biocontrol efficacy compared with CHA0-Rif. Cucumber was grown repeatedly in the same soil, which was left uninoculated, was inoculated with CHA0-Rif or CHA0-Rif(pME3424), or was treated with the fungicide metalaxyl (Ridomil). Treatments were applied to soil at the start of each 32-day-long cucumber growth cycle, and their effects on the diversity of the rhizosphere populations of culturable fungi were assessed at the end of the first and fifth cycles. Over 11,000 colonies were studied and assigned to 105 fungal species (plus several sterile morphotypes). The most frequently isolated fungal species (mainly belonging to the genera
Paecilomyces, Phialocephala, Fusarium, Gliocladium, Penicillium, Mortierella, Verticillium, Trichoderma, Staphylotrichum, Coniothyrium, Cylindrocarpon, Myrothecium
, and
Monocillium
) were common in the four treatments, and no fungal species was totally suppressed or found exclusively following one particular treatment. However, in each of the two growth cycles studied, significant differences were found between treatments (e.g., between the control and the other treatments and/or between the two inoculation treatments) using discriminant analysis. Despite these differences in the composition and/or relative abundance of species in the fungal community, treatments had no effect on species diversity indices, and species abundance distributions fit the truncated lognormal function in most cases. In addition, the impact of treatments at the 32-day mark of either growth cycle was smaller than the effect of growing cucumber repeatedly in the same soil.
Combined Use of 16S Ribosomal DNA and 16S rRNA To Study the Bacterial Community of Polychlorinated Biphenyl-Polluted Soil
Authors: Nogales Balbina , Moore Edward R. B. , Llobet-Brossa Enrique , Rossello-Mora Ramon , Amann Rudolf , Timmis Kenneth N. 
Published: July 2002

ABSTRACT

The bacterial diversity assessed from clone libraries prepared from rRNA (two libraries) and ribosomal DNA (rDNA) (one library) from polychlorinated biphenyl (PCB)-polluted soil has been analyzed. A good correspondence of the community composition found in the two types of library was observed. Nearly 29% of the cloned sequences in the rDNA library were identical to sequences in the rRNA libraries. More than 60% of the total cloned sequence types analyzed were grouped in phylogenetic groups (a clone group with sequence similarity higher than 97% [98% for
Burkholderia
and
Pseudomonas
-type clones]) represented in both types of libraries. Some of those phylogenetic groups, mostly represented by a single (or pair) of cloned sequence type(s), were observed in only one of the types of library. An important difference between the libraries was the lack of clones representative of the
Actinobacteria
in the rDNA library. The PCB-polluted soil exhibited a high bacterial diversity which included representatives of two novel lineages. The apparent abundance of bacteria affiliated to the beta-subclass of the
Proteobacteria
, and to the genus
Burkholderia
in particular, was confirmed by fluorescence in situ hybridization analysis. The possible influence on apparent diversity of low template concentrations was assessed by dilution of the RNA template prior to amplification by reverse transcription-PCR. Although differences in the composition of the two rRNA libraries obtained from high and low RNA concentrations were observed, the main components of the bacterial community were represented in both libraries, and therefore their detection was not compromised by the lower concentrations of template used in this study.
Enhanced Detection of Surface-Associated Bacteria in Indoor Environments by Quantitative PCR
Authors: Buttner Mark P. , Cruz-Perez Patricia , Stetzenbach Linda D. 
Published: July 2002

ABSTRACT

Methods for detecting microorganisms on surfaces are needed to locate biocontamination sources and to relate surface and airborne concentrations. Research was conducted in an experimental room to evaluate surface sampling methods and quantitative PCR (QPCR) for enhanced detection of a target biocontaminant present on flooring materials. QPCR and culture analyses were used to quantitate
Bacillus subtilis
(
Bacillus globigii
) endospores on vinyl tile, commercial carpet, and new and soiled residential carpet with samples obtained by four surface sampling methods: a swab kit, a sponge swipe, a cotton swab, and a bulk method. The initial data showed that greater overall sensitivity was obtained with the QPCR than with culture analysis; however, the QPCR results for bulk samples from residential carpet were negative. The swab kit and the sponge swipe methods were then tested with two levels of background biological contamination consisting of
Penicillium chrysogenum
spores. The
B. subtilis
values obtained by the QPCR method were greater than those obtained by culture analysis. The differences between the QPCR and culture data were significant for the samples obtained with the swab kit for all flooring materials except soiled residential carpet and with the sponge swipe for commercial carpet. The QPCR data showed that there were no significant differences between the swab kit and sponge swipe sampling methods for any of the flooring materials. Inhibition of QPCR due solely to biological contamination of flooring materials was not evident. However, some degree of inhibition was observed with the soiled residential carpet, which may have been caused by the presence of abiotic contaminants, alone or in combination with biological contaminants. The results of this research demonstrate the ability of QPCR to enhance detection and enumeration of biocontaminants on surface materials and provide information concerning the comparability of currently available surface sampling methods.
Reductive Precipitation of Gold by Dissimilatory Fe(III)-Reducing
Bacteria
and
Archaea
Authors: Kashefi Kazem , Tor Jason M. , Nevin Kelly P. , Lovley Derek R. 
Published: July 2002

ABSTRACT

Studies with a diversity of hyperthermophilic and mesophilic dissimilatory Fe(III)-reducing
Bacteria
and
Archaea
demonstrated that some of these organisms are capable of precipitating gold by reducing Au(III) to Au(0) with hydrogen as the electron donor. These studies suggest that models for the formation of gold deposits in both hydrothermal and cooler environments should consider the possibility that dissimilatory metal-reducing microorganisms can reductively precipitate gold from solution.
Sequence Analysis and Molecular Characterization of the
Lactococcus lactis
Temperate Bacteriophage BK5-T
Authors: Mahanivong Chitladda , Boyce John D. , Davidson Barrie E. , Hillier Alan J. 
Published: July 2002

ABSTRACT

The
Lactococcus lactis
temperate bacteriophage BK5-T is one of twelve type phages that define
L. lactis
phage species. This paper describes the nucleotide sequence and analysis of a 21-kbp region of the BK5-T genome and completes the nucleotide sequence of the genome of this phage. The 40,003-nucleotide linear genome encodes 63 open reading frames. Sequence runoff experiments showed that the cohesive ends of the BK5-T genome contained a 12-bp 3′ single-stranded overhang with the sequence 5′-CACACACATAGG-3′. Two major BK5-T structural proteins, of approximately 30 and 20 kDa, were identified, and N-terminal sequence analysis determined that they were encoded by
orf7
and
orf12
, respectively. A 169-bp fragment containing a 37-bp direct repeat and several smaller repeat sequences conferred resistance to BK5-T infection when introduced in
trans
to the host cell and is likely a part of the BK5-T origin of replication (
ori
).
Elucidation of the Flavonoid Catabolism Pathway in
Pseudomonas putida
PML2 by Comparative Metabolic Profiling
Authors: Pillai Bhinu V. S. , Swarup Sanjay 
Published: July 2002

ABSTRACT

Flavonoids are 15-carbon plant secondary metabolites exuded in the rhizosphere that hosts several flavonoid-degrading bacteria. We studied flavonoid catabolism in a plant growth-promoting rhizobacterial strain of
Pseudomonas
by using a combination of biochemical and genetic approaches. Transposants carrying mini-Tn
5gfp
insertions were screened for flavonoid auxotrophy, and these mutant strains were found to be unable to grow in the flavonols naringenin and quercetin, while their growth in glycerol was comparable to that of the parental strain. In order to understand flavonoid catabolism, culture supernatants, whole-cell fractions, cell lysate, and cell debris of the wild-type and mutant strains were analyzed. Intermediates that accumulated intracellularly and those secreted in the medium were identified by a combination of reversed-phase high-pressure liquid chromatography and electrospray ionization-mass spectrometry. Structures of four key intermediates were confirmed by one-dimensional nuclear magnetic resonance spectroscopy. Comparative metabolic profiling of the compounds in the wild-type and mutant strains allowed us to understand the degradation events and to identify six metabolic intermediates. The first step in the pathway involves 3,3′-didehydroxylation, followed by hydrolysis and cleavage of the C-ring, leading via subsequent oxidations to the formation of protocatechuate. This is the first report on quercetin dehydroxylation in aerobic conditions leading to naringenin accumulation.
Flux through Citrate Synthase Limits the Growth of EthanologenicEscherichia coliKO11 during Xylose Fermentation
Authors: Underwood S. A. , Buszko M. L. , Shanmugam K. T. , Ingram L. O. 
Published: July 2002

ABSTRACTPrevious studies have shown that high levels of complex nutrients (Luria broth or 5% corn steep liquor) were necessary for rapid ethanol production by the ethanologenic strainEscherichia coliKO11. Although this strain is prototrophic, cell density and ethanol production remained low in mineral salts media (10% xylose) unless complex nutrients were added. The basis for this nutrient requirement was identified as a regulatory problem created by metabolic engineering of an ethanol pathway. Cells must partition pyruvate between competing needs for biosynthesis and regeneration of NAD+. Expression of low-KmZymomonas mobilis pdc(pyruvate decarboxylase) in KO11 reduced the flow of pyruvate carbon into native fermentation pathways as desired, but it also restricted the flow of carbon skeletons into the 2-ketoglutarate arm of the tricarboxylic acid pathway (biosynthesis). In mineral salts medium containing 1% corn steep liquor and 10% xylose, the detrimental effect of metabolic engineering was substantially reduced by addition of pyruvate. A similar benefit was also observed when acetaldehyde, 2-ketoglutarate, or glutamate was added. InE. coli, citrate synthase links the cellular abundance of NADH to the supply of 2-ketoglutarate for glutamate biosynthesis. This enzyme is allosterically regulated and inhibited by high NADH concentrations. In addition, citrate synthase catalyzes the first committed step in 2-ketoglutarate synthesis. Oxidation of NADH by added acetaldehyde (or pyruvate) would be expected to increase the activity ofE. colicitrate synthase and direct more carbon into 2-ketoglutarate, and this may explain the stimulation of growth. This hypothesis was tested, in part, by cloning theBacillus subtilis citZgene encoding an NADH-insensitive citrate synthase. Expression of recombinantcitZin KO11 was accompanied by increases in cell growth and ethanol production, which substantially reduced the need for complex nutrients.
Cloning of
Escherichia coli lacZ
and
lacY
Genes and Their Expression in
Gluconobacter oxydans
and
Acetobacter liquefaciens
Authors: Mostafa Hesham E. , Heller Knut J. , Geis Arnold 
Published: July 2002

ABSTRACT

An efficient transformation protocol for
Gluconobacter oxydans
and
Acetobacter liquefaciens
strains was developed by preparation of electrocompetent cells grown on yeast extract-ethanol medium. Plasmid pBBR122 was used as broad-host-range vector to clone the
Escherichia coli lacZY
genes in
G. oxydans
and
A. liquefaciens.
Although both
lac
genes were functionally expressed in both acetic acid bacteria
,
only a few transformants were able to grow on lactose. However, this ability strictly depended on the presence of a plasmid expressing both
lac
genes. Mutations in the plasmids and/or in the chromosome were excluded as the cause of growth ability on lactose.
Identification of OpuC as a Chill-Activated and Osmotically Activated Carnitine Transporter in
Listeria monocytogenes
Authors: Angelidis Apostolos S. , Smith Linda Tombras , Hoffman Les M. , Smith Gary M. 
Published: July 2002

ABSTRACT

The food-borne pathogen
Listeria monocytogenes
is notable for its ability to grow under osmotic stress and at low temperatures. It is known to accumulate the compatible solutes glycine betaine and carnitine from the medium in response to osmotic or chill stress, and this accumulation confers tolerance to these stresses. Two permeases that transport glycine betaine have been identified, both of which are activated by hyperosmotic stress and one of which is activated by low temperature. An osmotically activated transporter for carnitine, OpuC, has also been identified. We have isolated a Tn
917
-LTV3 insertional mutant that could not be rescued from hyperosmotic stress by exogenous carnitine. The mutant, LTS4a, grew indistinguishably from a control strain (DP-L1044) in the absence of stress or in the absence of carnitine, but DP-L1044 grew substantially faster under osmotic or chill stress in the presence of carnitine. LTS4a was found to be strongly impaired in KCl-activated as well as chill-activated carnitine transport.
13
C nuclear magnetic resonance spectroscopy of perchloric acid extracts showed that accumulation of carnitine by LTS4a was negligible under all conditions tested. Direct sequencing of LTS4a genomic DNA with a primer based on Tn
917
-LTV3 yielded a 487-bp sequence, which allowed us to determine that the
opuC
operon had been interrupted by the transposon. It can be concluded that
opuC
encodes a carnitine transporter that can be activated by either hyperosmotic stress or chill and that the transport system plays a significant role in the tolerance of
L. monocytogenes
to both forms of environmental stress.
CD4+Lymphocyte-Mediated Suppression of Cytomegalovirus Expression in Human Astrocytes
Authors: Cheeran Maxim C.-J. , Gekker Genya , Hu Shuxian , Yager Stephanie L. , Peterson Phillip K. , Lokensgard James R. 
Published: July 2002

ABSTRACTCytomegalovirus-stimulated CD4+lymphocytes from seropositive but not seronegative donors suppressed viral gene expression in primary human astrocytes. This suppressive activity was mediated through soluble factors. These findings suggest that CD4+lymphocytes play a role in defense of the brain against cytomegalovirus.
Immunization of BALB/c Mice with KilledNeospora caninumTachyzoite Antigen Induces a Type 2 Immune Response and Exacerbates Encephalitis and Neurological Disease
Authors: Baszler Timothy V. , McElwain Terry F. , Mathison Bruce A. 
Published: July 2002

ABSTRACTBALB/c mice were immunized subcutaneously with solubleNeospora caninumtachyzoite antigen (NSO) entrapped in nonionic surfactant vesicles (NISVs) or administered with Freund's complete adjuvant (FCA). Following virulent parasite challenge, groups of mice immunized with NSO and either NISVs or FCA had clinical neurological disease and increased numbers of brain lesions compared to groups of mice inoculated with FCA, NISVs, or phosphate-buffered saline (PBS) alone. Increased numbers of brain lesions were statistically significant only between mice immunized with NISV-NSO and NISV- or PBS-treated mice. Following parasite challenge, brain inflammatory infiltrates in all experimental and control groups of mice were relatively similar and consisted of compact infiltrates of macrophages admixed with various numbers of lymphoid cells. Increased brain lesions in NSO-immunized mice were associated with increased antigen-specific interleukin 4 (IL-4) secretion and increased IL-4:gamma interferon secretion ratios from splenocytes in vitro and increased antigen-specific immunoglobulin G1 (IgG1):IgG2a ratios in vivo. Thus, immunization with whole killedN. caninumantigen and either liposoidal or Freund's adjuvant induced a type 2 immune response that was associated with worsened disease. The present studies emphasize the need to identify specificN. caninumantigens or other delivery systems that will elicit protective immune responses to neosporosis.
In Vitro Hydroxyurea Decreases Th1 Cell-Mediated Immunity
Authors: Weinberg Adriana 
Published: July 2002

ABSTRACT
Hydroxyurea (HU) is used in the treatment of hematologic disorders and is sometimes added to antiretroviral combination therapy to potentiate human immunodeficiency virus (HIV) suppression. However, HU has toxic effects on rapidly dividing cells, including the effectors of the immune response. To determine whether HU affects specific T-cell responses, we measured lymphocyte proliferation and cytokine production in response to microbial antigen and mitogen stimulation in the presence of added HU (10 to 1,000 μM). HU treatment of peripheral blood mononuclear cells obtained from HIV-infected patients and uninfected controls decreased lymphocyte proliferation and gamma interferon production compared with untreated cells. Interleukin-2 (IL-2) and IL-10 production was not affected by HU. The HU-mediated decrease of lymphocyte proliferation was similar in peripheral blood mononuclear cells from HIV-infected patients and from uninfected controls. The inhibitory effect of HU required continuous exposure to the drug and could be reverted by washing the drug out of the culture environment. These findings suggest that HU-containing therapeutic regimens might decrease Th1-cell-mediated immune responses in vivo.