bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rhizosphere Communities of Genetically Modified Zeaxanthin-Accumulating Potato Plants and Their Parent Cultivar Differ Less than Those of Different Potato Cultivars
Authors: Weinert Nicole , Meincke Remo , Gottwald Christine , Heuer Holger , Gomes Newton C. M. , Schloter Michael , Berg Gabriele , Smalla Kornelia 
Published: April 2009

ABSTRACT

The effects of genetically modified (GM), zeaxanthin-accumulating potato plants on microbial communities in the rhizosphere were compared to the effects of different potato cultivars. Two GM lines and their parental cultivar, as well as four other potato cultivars, were grown in randomized field plots at two sites and in different years. Rhizosphere samples were taken at three developmental stages during plant growth and analyzed using denaturing gradient gel electrophoresis (DGGE) fingerprints of
Bacteria
,
Actinobacteria
,
Alpha
- and
Betaproteobacteria
,
Bacillus
,
Streptomycetaceae
,
Pseudomonas
,
gacA
,
Fungi
, and
Ascomycetes
. In the bacterial DGGE gels analyzed, significant differences between the parental cultivar and the two GM lines were detected mainly for
Actinobacteria
but also for
Betaproteobacteria
and
Streptomycetaceae
, yet these differences occurred only at one site and in one year. Significant differences occurred more frequently for
Fungi
, especially
Ascomycetes
, than for bacteria. When all seven plant genotypes were compared, DGGE analysis revealed that different cultivars had a greater effect on both bacterial and fungal communities than genetic modification. The effects of genetic modification were detected mostly at the senescence developmental stage of the plants. The site was the overriding factor affecting microbial community structure compared to the plant genotype. In general, the fingerprints of the two GM lines were more similar to that of the parental cultivar, and the differences observed did not exceed natural cultivar-dependent variability.
Susceptibility of
Diabrotica virgifera virgifera
(Coleoptera: Chrysomelidae) to the Entomopathogenic Fungus
Metarhizium anisopliae
when Feeding on
Bacillus thuringiensis
Cry3Bb1-Expressing Maize
Authors: Meissle Michael , Pilz Christina , Romeis Jörg 
Published: April 2009

ABSTRACT

Genetically engineered maize producing the insecticidal protein Cry3Bb1 from
Bacillus thuringiensis
(Bt maize) is protected against corn rootworms (
Diabrotica
spp.), which are serious maize pests in North America and Europe. The aim of the present study was to investigate the interaction of Bt maize (event MON88017) and the entomopathogenic fungus
Metarhizium anisopliae
for controlling the western corn rootworm,
Diabrotica virgifera virgifera
. Exposure to Cry3Bb1 expressed in Bt maize seedlings resulted in decreased weight gain in
D. v. virgifera
larvae but did not influence susceptibility to
M. anisopliae
. Adult beetles were not affected by Cry3Bb1 in their food, but mortality when feeding on maize leaves was higher than when feeding on silk. Adults were more susceptible to the fungus than larvae. The results indicate that the effects of Bt maize and
M. anisopliae
on
D. v. virgifera
are additive and that Bt maize does not interfere with the biological control provided by entomopathogenic fungi.
Ferricrocin, a Siderophore Involved in Intra- and Transcellular Iron Distribution in
Aspergillus fumigatus
Authors: Wallner Anja , Blatzer Michael , Schrettl Markus , Sarg Bettina , Lindner Herbert , Haas Hubertus 
Published: April 2009

ABSTRACT

Iron is an essential metal for virtually all organisms. Iron acquisition is well characterized for various organisms, whereas intracellular iron distribution is poorly understood. In contrast to bacteria, plants, and animals, most fungi lack ferritin-mediated iron storage but possess an intracellular siderophore shown to be involved in iron storage. Here we demonstrate that deficiency in the intracellular siderophore ferricrocin causes iron starvation in conidia of
Aspergillus fumigatus
, demonstrating that ferricrocin is also involved in intra- and transcellular iron distribution. Thus, ferricrocin represents the first intracellular iron transporter identified in any organism.
Phenol Degradation in the Strictly Anaerobic Iron-Reducing Bacterium
Geobacter metallireducens
GS-15
Authors: Schleinitz Kathleen M. , Schmeling Sirko , Jehmlich Nico , von Bergen Martin , Harms Hauke , Kleinsteuber Sabine , Vogt Carsten , Fuchs Georg 
Published: April 2009

ABSTRACT

Information on anaerobic phenol metabolism by physiological groups of bacteria other than nitrate reducers is scarce. We investigated phenol degradation in the strictly anaerobic iron-reducing deltaproteobacterium
Geobacter metallireducens
GS-15 using metabolite, transcriptome, proteome, and enzyme analyses. The results showed that the initial steps of phenol degradation are accomplished by phenylphosphate synthase (encoded by
pps
genes) and phenylphosphate carboxylase (encoded by
ppc
genes) as known from
Thauera aromatica
, but they also revealed some distinct differences. The
pps
-
ppc
gene cluster identified in the genome is functional, as shown by transcription analysis. In contrast to
T. aromatica
, transcription of the
pps-
and
ppc
-like genes was induced not only during growth on phenol, but also during growth on benzoate. In contrast, proteins were detected only during growth on phenol, suggesting the existence of a posttranscriptional regulation mechanism for these initial steps. Phenylphosphate synthase and phenylphosphate carboxylase activities were detected in cell extracts. The carboxylase does not catalyze an isotope exchange reaction between
14
CO
2
and 4-hydroxybenzoate, which is characteristic of the
T. aromatica
enzyme. Whereas the enzyme of
T. aromatica
is encoded by
ppcABCD
, the
pps
-
ppc
gene cluster of
G. metallireducens
contains only a
ppcB
homologue. Nearby, but oriented in the opposite direction, is a
ppcD
homologue that is transcribed during growth on phenol. Genome analysis did not reveal obvious homologues of
ppcA
and
ppcC
, leaving open the question of whether these genes are dispensable for phenylphosphate carboxylase activity in
G. metallireducens
or are quite different from the
Thauera
counterparts and located elsewhere in the genome.
Bacterial Communities from Shoreline Environments (Costa da Morte, Northwestern Spain) Affected by the
Prestige
Oil Spill
Authors: Alonso-Gutiérrez Jorge , Figueras Antonio , Albaigés Joan , Jiménez Núria , Viñas Marc , Solanas Anna M. , Novoa Beatriz 
Published: April 2009

ABSTRACT

The bacterial communities in two different shoreline matrices, rocks and sand, from the Costa da Morte, northwestern Spain, were investigated 12 months after being affected by the
Prestige
oil spill. Culture-based and culture-independent approaches were used to compare the bacterial diversity present in these environments with that at a nonoiled site. A long-term effect of fuel on the microbial communities in the oiled sand and rock was suggested by the higher proportion of alkane and polyaromatic hydrocarbon (PAH) degraders and the differences in denaturing gradient gel electrophoresis patterns compared with those of the reference site. Members of the classes
Alphaproteobacteria
and
Actinobacteria
were the prevailing groups of bacteria detected in both matrices, although the sand bacterial community exhibited higher species richness than the rock bacterial community did. Culture-dependent and -independent approaches suggested that the genus
Rhodococcus
could play a key role in the in situ degradation of the alkane fraction of the
Prestige
fuel together with other members of the suborder
Corynebacterineae
. Moreover, other members of this suborder, such as
Mycobacterium
spp., together with
Sphingomonadaceae
bacteria (mainly
Lutibacterium anuloederans
), were related as well to the degradation of the aromatic fraction of the
Prestige
fuel. The multiapproach methodology applied in the present study allowed us to assess the complexity of autochthonous microbial communities related to the degradation of heavy fuel from the
Prestige
and to isolate some of their components for a further physiological study. Since several
Corynebacterineae
members related to the degradation of alkanes and PAHs were frequently detected in this and other supralittoral environments affected by the
Prestige
oil spill along the northwestern Spanish coast, the addition of mycolic acids to bioremediation amendments is proposed to favor the presence of these degraders in long-term fuel pollution-affected areas with similar characteristics.
Induction of Extracellular Hydroxyl Radical Production by White-Rot Fungi through Quinone Redox Cycling
Authors: Gómez-Toribio Víctor , García-Martín Ana B. , Martínez María J. , Martínez Ángel T. , Guillén Francisco 
Published: April 2009

ABSTRACT

A simple strategy for the induction of extracellular hydroxyl radical (OH) production by white-rot fungi is presented. It involves the incubation of mycelium with quinones and Fe
3+
-EDTA. Succinctly, it is based on the establishment of a quinone redox cycle catalyzed by cell-bound dehydrogenase activities and the ligninolytic enzymes (laccase and peroxidases). The semiquinone intermediate produced by the ligninolytic enzymes drives OH production by a Fenton reaction (H
2
O
2
+ Fe
2+
→ OH + OH
−
+ Fe
3+
). H
2
O
2
production, Fe
3+
reduction, and OH generation were initially demonstrated with two
Pleurotus eryngii
mycelia (one producing laccase and versatile peroxidase and the other producing just laccase) and four quinones, 1,4-benzoquinone (BQ), 2-methoxy-1,4-benzoquinone (MBQ), 2,6-dimethoxy-1,4-benzoquinone (DBQ), and 2-methyl-1,4-naphthoquinone (menadione [MD]). In all cases, OH radicals were linearly produced, with the highest rate obtained with MD, followed by DBQ, MBQ, and BQ. These rates correlated with both H
2
O
2
levels and Fe
3+
reduction rates observed with the four quinones. Between the two
P. eryngii
mycelia used, the best results were obtained with the one producing only laccase, showing higher OH production rates with added purified enzyme. The strategy was then validated in
Bjerkandera adusta
,
Phanerochaete chrysosporium
,
Phlebia radiata
,
Pycnoporus cinnabarinus
, and
Trametes versicolor
, also showing good correlation between OH production rates and the kinds and levels of the ligninolytic enzymes expressed by these fungi. We propose this strategy as a useful tool to study the effects of OH radicals on lignin and organopollutant degradation, as well as to improve the bioremediation potential of white-rot fungi.
Enhancing the Production of Hydroxyl Radicals byPleurotus eryngiivia Quinone Redox Cycling for Pollutant Removal
Authors: Gómez-Toribio Víctor , García-Martín Ana B. , Martínez María J. , Martínez Ángel T. , Guillén Francisco 
Published: April 2009

ABSTRACTThe induction of hydroxyl radical (OH) production via quinone redox cycling in white-rot fungi was investigated to improve pollutant degradation. In particular, we examined the influence of 4-methoxybenzaldehyde (anisaldehyde), Mn2+, and oxalate onPleurotus eryngiiOH generation. Our standard quinone redox cycling conditions combined mycelium from laccase-producing cultures with 2,6-dimethoxy-1,4-benzoquinone (DBQ) and Fe3+-EDTA. The main reactions involved in OH production under these conditions have been shown to be (i) DBQ reduction to hydroquinone (DBQH2) by cell-bound dehydrogenase activities; (ii) DBQH2oxidation to semiquinone (DBQ−) by laccase; (iii) DBQ−autoxidation, catalyzed by Fe3+-EDTA, producing superoxide (O2−) and Fe2+-EDTA; (iv) O2−dismutation, generating H2O2; and (v) the Fenton reaction. Compared to standard quinone redox cycling conditions, OH production was increased 1.2- and 3.0-fold by the presence of anisaldehyde and Mn2+, respectively, and 3.1-fold by substituting Fe3+-EDTA with Fe3+-oxalate. A 6.3-fold increase was obtained by combining Mn2+and Fe3+-oxalate. These increases were due to enhanced production of H2O2via anisaldehyde redox cycling and O2−reduction by Mn2+. They were also caused by the acceleration of the DBQ redox cycle as a consequence of DBQH2oxidation by both Fe3+-oxalate and the Mn3+generated during O2−reduction. Finally, induction of OH production through quinone redox cycling enabledP. eryngiito oxidize phenol and the dye reactive black 5, obtaining a high correlation between the rates of OH production and pollutant oxidation.
Carbazole-Degradative IncP-7 Plasmid pCAR1.2 Is Structurally Unstable in
Pseudomonas fluorescens
Pf0-1, Which Accumulates Catechol, the Intermediate of the Carbazole Degradation Pathway
Authors: Takahashi Yurika , Shintani Masaki , Li Li , Yamane Hisakazu , Nojiri Hideaki 
Published: April 2009

ABSTRACT

We determined the effect of the host on the function and structure of the nearly identical IncP-7 carbazole-degradative plasmids pCAR1.1 and pCAR1.2. We constructed
Pseudomonas aeruginosa
PAO1(pCAR1.2) and
P. fluorescens
Pf0-1Km(pCAR1.2) and compared their growth on carbazole- and succinate-containing media with that of
P. putida
KT2440(pCAR1.1). We also assessed the stability of the genetic structures of the plasmids in each of the three hosts. Pf0-1Km(pCAR1.2) showed dramatically delayed growth when carbazole was supplied as the sole carbon source, while the three strains grew at nearly the same rate on succinate. Among the carbazole-grown Pf0-1Km(pCAR1.2) cells, two types of deficient strains appeared and dominated the population; such dominance was not observed in the other two strains or for succinate-grown Pf0-1Km(pCAR1.2). Genetic analysis showed that the two deficient strains possessed pCAR1.2 derivatives in which the carbazole-degradative
car
operon was deleted or its regulatory gene,
antR
, was deleted by homologous recombination between insertion sequences. From genomic information and quantitative reverse transcription-PCR analyses of the genes involved in carbazole mineralization by Pf0-1Km(pCAR1.2), we found that the
cat
genes on the chromosome of Pf0-1Km, which are necessary for the degradation of catechol (a toxic intermediate in the carbazole catabolic pathway), were not induced in the presence of carbazole. The resulting accumulation of catechol may have enabled the strain that lost its carbazole-degrading ability to have overall higher fitness than the wild-type strain. These results suggest that the functions of the chromosomal genes contributed to the selection of plasmid derivatives with altered structures.
Role of Ceftiofur in Selection and Dissemination of
bla
CMY-2
-Mediated Cephalosporin Resistance in
Salmonella enterica
and Commensal
Escherichia coli
Isolates from Cattle
Authors: Daniels Joshua B. , Call Douglas R. , Hancock Dale , Sischo William M. , Baker Katherine , Besser Thomas E. 
Published: April 2009

ABSTRACT

Third-generation cephalosporin resistance of
Salmonella
and commensal
Escherichia coli
isolates from cattle in the United States is predominantly conferred by the cephamycinase CMY-2, which inactivates β-lactam antimicrobial drugs used to treat a wide variety of infections, including pediatric salmonellosis. The emergence and dissemination of
bla
CMY-2
-
-bearing plasmids followed and may in part be the result of selection pressure imposed by the widespread utilization of ceftiofur, a third-generation veterinary cephalosporin. This study assessed the potential effects of ceftiofur on
bla
CMY-2
transfer and dissemination by (i) an in vivo experimental study in which calves were inoculated with competent
bla
CMY-2
-bearing plasmid donors and susceptible recipients and then subjected to ceftiofur selection and (ii) an observational study to determine whether ceftiofur use in dairy herds is associated with the occurrence and frequency of cephalosporin resistance in
Salmonella
and commensal
E. coli
. The first study revealed
bla
CMY-2
plasmid transfer in both ceftiofur-treated and untreated calves but detected no enhancement of plasmid transfer associated with ceftiofur treatment. The second study detected no association (
P
= 0.22) between ceftiofur use and either the occurrence of ceftiofur-resistant salmonellosis or the frequency of cephalosporin resistance in commensal
E. coli
. However, herds with a history of salmonellosis (including both ceftiofur-resistant and ceftiofur-susceptible
Salmonella
isolates) used more ceftiofur than herds with no history of salmonellosis (
P
= 0.03) These findings fail to support a major role for ceftiofur use in the maintenance and dissemination of
bla
CMY-2
-bearing plasmid mediated cephalosporin resistance in commensal
E. coli
and in pathogenic
Salmonella
in these dairy cattle populations.
Effect of Amino Acid Availability on Vitamin B
12
Production in
Lactobacillus reuteri
Authors: Santos Filipe , Teusink Bas , Molenaar Douwe , van Heck Maurice , Wels Michiel , Sieuwerts Sander , de Vos Willem M. , Hugenholtz Jeroen 
Published: April 2009

ABSTRACT

Recent functional genomics and genome-scale modeling approaches indicated that B
12
production in
Lactobacillus reuteri
could be improved by optimization of the medium. Here we show that a series of systematic single-amino-acid omissions could significantly modulate the production of B
12
from nearly undetectable levels (with omission of isoleucine) to levels 20-fold higher than the levels previously reported (with omission of cysteine). Using cDNA microarray experiments, we analyzed the transcriptional response of
L. reuteri
to medium lacking cysteine. The results supported the observed high level of B
12
production and provided new avenues for future improvement of production of vitamin B
12
.
Characterization of P450 FcpC, the Enzyme Responsible for Bioconversion of Diosgenone to Isonuatigenone in
Streptomyces virginiae
IBL-14
Authors: Wang Wei , Wang Feng-Qing , Wei Dong-Zhi 
Published: April 2009

ABSTRACT

A new cytochrome P450 monooxygenase, FcpC, from
Streptomyces virginiae
IBL-14 has been identified. This enzyme is found to be responsible for the bioconversion of a pyrano-spiro steroid (diosgenone) to a rare nuatigenin-type spiro steroid (isonuatigenone), which is a novel C-25-hydroxylated diosgenone derivative. A whole-cell P450 system was developed for the production of isonuatigenone via the expression of the complete three-component electron transfer chain in an
Escherichia coli
strain.
CpxRA Contributes to
Xenorhabdus nematophila
Virulence through Regulation of
lrhA
and Modulation of Insect Immunity
Authors: Herbert Tran Erin E. , Goodrich-Blair Heidi 
Published: April 2009

ABSTRACT

The gammaproteobacterium
Xenorhabdus nematophila
is a blood pathogen of insects that requires the CpxRA signal transduction system for full virulence (E. E. Herbert et al., Appl. Environ. Microbiol. 73:7826-7836, 2007). We show here that the Δ
cpxR1
mutant has altered localization, growth, and immune suppressive activities relative to its wild-type parent during infection of
Manduca sexta
insects. In contrast to wild-type
X. nematophila
, which were recovered throughout infection, Δ
cpxR1
cells did not accumulate in hemolymph until after insect death. In vivo imaging of fluorescently labeled bacteria within live insects showed that Δ
cpxR1
displayed delayed accumulation and also occasionally were present in isolated nodes rather than systemically throughout the insect as was wild-type
X. nematophila
. In addition, in contrast to its wild-type parent, the Δ
cpxR1
mutant elicited transcription of an insect antimicrobial peptide, cecropin. Relative to phosphate-buffered saline-injected insects, cecropin transcript was induced 21-fold more in insects injected with Δ
cpxR1
and 2-fold more in insects injected with wild-type
X. nematophila
. These data suggest that the Δ
cpxR1
mutant has a defect in immune suppression or has an increased propensity to activate
M. sexta
immunity. CpxR regulates, directly or indirectly, genes known or predicted to be involved in virulence (E. E. Herbert et al., Appl. Environ. Microbiol. 73:7826-7836, 2007), including
lrhA
, encoding a transcription factor necessary for
X. nematophila
virulence, motility, and lipase production (G. R. Richards et al., J. Bacteriol. 190:4870-4879, 2008). CpxR positively regulates
lrhA
transcript, and we have shown that altered regulation of
lrhA
in the Δ
cpxR1
mutant causes this strain's virulence defect. The Δ
cpxR1
mutant expressing
lrhA
from a constitutive
lac
promoter showed wild-type virulence in
M. sexta
. These data suggest that CpxR contributes to
X. nematophila
virulence through the regulation of
lrhA
, immune suppression, and growth in
Insecta
.
Multiple-Locus Variable-Number Tandem-Repeat Analysis for Clonal Identification of
Vibrio parahaemolyticus
Isolates by Using Capillary Electrophoresis
Authors: Harth-Chu Erika , Espejo Romilio T. , Christen Richard , Guzmán Carlos A. , Höfle Manfred G. 
Published: April 2009

ABSTRACT

Epidemics of
Vibrio parahaemolyticus
in Chile have occurred since 1998. Direct genome restriction enzyme analysis (DGREA) using conventional gel electrophoresis permitted discrimination of different
V. parahaemolyticus
isolates obtained from these outbreaks and showed that this species consists of a highly diverse population. A multiple-locus variable-number tandem-repeat (VNTR) analysis (MLVA) approach was developed and applied to 22 clinical and 91 environmental
V. parahaemolyticus
isolates from Chile to understand their clonal structures. To this end, an advanced molecular technique was developed by applying multiplex PCR, fluorescent primers, and capillary electrophoresis, resulting in a high-resolution and high-throughput (HRHT) genotyping method. The genomic basis of this HRHT method was eight VNTR loci described previously by Kimura et al. (J. Microbiol. Methods 72:313-320, 2008) and two new loci which were identified by a detailed molecular study of 24 potential VNTR loci on both chromosomes. The isolates of
V. parahaemolyticus
belonging to the same DGREA pattern were distinguishable by the size variations in the indicative 10 VNTRs. This assay showed that these 10 VNTR loci were useful for distinguishing isolates of
V. parahaemolyticus
that had different DGREA patterns and also isolates that belong to the same group. Isolates that differed in their DGREA patterns showed polymorphism in their VNTR profiles. A total of 81 isolates was associated with 59 MLVA groups, providing fine-scale differentiation, even among very closely related isolates. The developed approach enables rapid and high-resolution analysis of
V. parahaemolyticus
with pandemic potential and provides a new surveillance tool for food-borne pathogens.