bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidation of Benzene to Phenol, Catechol, and 1,2,3-Trihydroxybenzene by Toluene 4-Monooxygenase of
Pseudomonas mendocina
KR1 and Toluene 3-Monooxygenase of
Ralstonia pickettii
PKO1
Authors: Tao Ying , Fishman Ayelet , Bentley William E. , Wood Thomas K. 
Published: July 2004

ABSTRACT

Aromatic hydroxylations are important bacterial metabolic processes but are difficult to perform using traditional chemical synthesis, so to use a biological catalyst to convert the priority pollutant benzene into industrially relevant intermediates, benzene oxidation was investigated. It was discovered that toluene 4-monooxygenase (T4MO) of
Pseudomonas mendocina
KR1, toluene 3-monooxygenase (T3MO) of
Ralstonia pickettii
PKO1, and toluene
ortho
-monooxygenase (TOM) of
Burkholderia cepacia
G4 convert benzene to phenol, catechol, and 1,2,3-trihydroxybenzene by successive hydroxylations. At a concentration of 165 μM and under the control of a constitutive
lac
promoter,
Escherichia coli
TG1/pBS(Kan)T4MO expressing T4MO formed phenol from benzene at 19 ± 1.6 nmol/min/mg of protein, catechol from phenol at 13.6 ± 0.3 nmol/min/mg of protein, and 1,2,3-trihydroxybenzene from catechol at 2.5 ± 0.5nmol/min/mg of protein. The catechol and 1,2,3-trihydroxybenzene products were identified by both high-pressure liquid chromatography and mass spectrometry. When analogous plasmid constructs were used,
E. coli
TG1/pBS(Kan)T3MO expressing T3MO formed phenol, catechol, and 1,2,3-trihydroxybenzene at rates of 3 ± 1, 3.1 ± 0.3, and 0.26 ± 0.09 nmol/min/mg of protein, respectively, and
E. coli
TG1/pBS(Kan)TOM expressing TOM formed 1,2,3-trihydroxybenzene at a rate of 1.7 ± 0.3 nmol/min/mg of protein (phenol and catechol formation rates were 0.89 ± 0.07 and 1.5 ± 0.3 nmol/min/mg of protein, respectively). Hence, the rates of synthesis of catechol by both T3MO and T4MO and the 1,2,3-trihydroxybenzene formation rate by TOM were found to be comparable to the rates of oxidation of the natural substrate toluene for these enzymes (10.0 ± 0.8, 4.0 ± 0.6, and 2.4 ± 0.3 nmol/min/mg of protein for T4MO, T3MO, and TOM, respectively, at a toluene concentration of 165 μM).
Impact of Heterologous Expression of
Escherichia coli
UDP-Glucose Pyrophosphorylase on Trehalose and Glycogen Synthesis in
Corynebacterium glutamicum
Authors: Padilla Leandro , Morbach Susanne , Krämer Reinhard , Agosin Eduardo 
Published: July 2004

ABSTRACT

Trehalose is a disaccharide with a wide range of applications in the food industry. We recently proposed a strategy for trehalose production based on improved strains of the gram-positive bacterium
Corynebacterium glutamicum
. This microorganism synthesizes trehalose through two major pathways, OtsBA and TreYZ, by using UDP-glucose and ADP-glucose, respectively, as the glucosyl donors. In this paper we describe improvement of the UDP-glucose supply through heterologous expression in
C. glutamicum
of the UDP-glucose pyrophosphorylase gene from
Escherichia coli
, either expressed alone or coexpressed with the
E. coli ots
genes (
galU otsBA
synthetic operon). The impact of such expression on trehalose accumulation and excretion, glycogen accumulation, and the growth pattern of new recombinant strains is described. Expression of the
galU otsBA
synthetic operon resulted in a sixfold increase in the accumulated and excreted trehalose relative to that in a wild-type strain. Surprisingly, single expression of
galU
also resulted in an increase in the accumulated trehalose. This increase in trehalose synthesis was abolished upon deletion of the TreYZ pathway. These results proved that UDP-glucose has an important role not only in the OtsBA pathway but also in the TreYZ pathway.
Longitudinal Study of
Campylobacter jejuni
Bacteriophages and Their Hosts from Broiler Chickens
Authors: Connerton P. L. , Loc Carrillo C. M. , Swift C. , Dillon E. , Scott A. , Rees C. E. D. , Dodd C. E. R. , Frost J. , Connerton I. F. 
Published: July 2004

ABSTRACT

A longitudinal study of bacteriophages and their hosts was carried out at a broiler house that had been identified as having a population of
Campylobacter
-specific bacteriophages. Cloacal and excreta samples were collected from three successive broiler flocks reared in the same barn.
Campylobacter jejuni
was isolated from each flock, whereas bacteriophages could be isolated from flocks 1 and 2 but were not isolated from flock 3. The bacteriophages isolated from flocks 1 and 2 were closely related to each other in terms of host range, morphology, genome size, and genetic content. All
Campylobacter
isolates from flock 1 were genotypically indistinguishable by pulsed-field gel electrophoresis (PFGE). PFGE and multilocus sequence typing indicated that this
C. jejuni
type was maintained from flock 1 to flock 2 but was largely superseded by three genetically distinct
C. jejuni
types insensitive to the resident bacteriophages. All isolates from the third batch of birds were insensitive to bacteriophages and genotypically distinct. These results are significant because this is the first study of an environmental population of
C. jejuni
bacteriophages and their influence on the
Campylobacter
populations of broiler house chickens. The role of developing bacteriophage resistance was investigated as this is a possible obstacle to the use of bacteriophage therapy to reduce the numbers of campylobacters in chickens. In this broiler house succession was largely due to incursion of new genotypes rather than to de novo development of resistance.
Comparison of
Euryarchaea
Strains in the Guts and Food-Soil of the Soil-Feeding Termite
Cubitermes fungifaber
across Different Soil Types
Authors: Donovan S. E. , Purdy K. J. , Kane M. D. , Eggleton P. 
Published: July 2004

ABSTRACT

Termites are an important component of tropical soil communities and have a significant effect on the structure and nutrient content of soil. Digestion in termites is related to gut structure, gut physicochemical conditions, and gut symbiotic microbiota. Here we describe the use of 16S rRNA gene sequencing and terminal-restriction fragment length polymorphism (T-RFLP) analysis to examine methanogenic archaea (MA) in the guts and food-soil of the soil-feeder
Cubitermes fungifaber
Sjostedt across a range of soil types. If these MA are strictly vertically inherited, then the MA in guts should be the same in all individuals even if the soils differ across sites. In contrast, gut MA should reflect what is present in soil if populations are merely a reflection of what is ingested as the insects forage. We show clear differences between the euryarchaeal communities in termite guts and in food-soils from five different sites. Analysis of 16S rRNA gene clones indicated little overlap between the gut and soil communities. Gut clones were related to a termite-derived
Methanomicrobiales
cluster, to
Methanobrevibacter
and, surprisingly, to the haloalkaliphile
Natronococcus
. Soil clones clustered with
Methanosarcina
,
Methanomicrococcus
, or rice cluster I. T-RFLP analysis indicated that the archaeal communities in the soil samples differed from site to site, whereas those in termite guts were similar between sites. There was some overlap between the gut and soil communities, but these may represent transient populations in either guts or soil. Our data do not support the hypothesis that termite gut MA are derived from their food-soil but also do not support a purely vertical transmission of gut microflora.
Isolation and Characterization of
Micromonospora
Phage ΦHAU8 and Development into a Phasmid
Authors: Li Xiaohua , Zhou Xiufen , Deng Zixin 
Published: July 2004

ABSTRACT

ΦHAU8, a temperate
Micromonospora
phage, which is capable of infecting
Micromonospora
sp. strains 40027 and A-M-01, was isolated. The ΦHAU8 virion has a polyhedral head and a flexible tail and has a small genome (ca. 42.5 kb) with double-stranded DNA and cohesive ends. ΦHAU8 was most stable at 4°C in Difco nutrient broth within a pH range of 6 to 12. ΦHAU8 plaque formation on
Micromonospora
sp. strain 40027 was optimal with 32 mM Ca
2+
and 30 mM Mg
2+
. A lysogen, LXH8, was isolated from turbid plaques, and a phasmid derivative that functions as a λ cosmid vector in
Escherichia coli
and as a phage in
Micromonospora
sp. strain 40027 was constructed. Pulsed-field gel electrophoresis of AseI-digested total DNA showed that ΦHAU8 DNA integrates into the 500-kb AseI fragment of
Micromonospora
sp. strain 40027.
Serotypes and Virulence Gene Profiles of Shiga Toxin-Producing
Escherichia coli
Strains Isolated from Feces of Pasture-Fed and Lot-Fed Sheep
Authors: Djordjevic Steven P. , Ramachandran Vidiya , Bettelheim Karl A. , Vanselow Barbara A. , Holst Peter , Bailey Graham , Hornitzky Michael A. 
Published: July 2004

ABSTRACT

Shiga toxin-producing
Escherichia coli
(STEC) strains possessing genes for enterohemolysin (
ehxA
) and/or intimin (
eae
), referred to here as complex STEC (cSTEC), are more commonly recovered from the feces of humans with hemolytic uremic syndrome and hemorrhagic colitis than STEC strains that do not possess these accessory virulence genes. Ruminants, particularly cattle and sheep, are recognized reservoirs of STEC populations that may contaminate foods destined for human consumption. We isolated cSTEC strains from the feces of longitudinally sampled pasture-fed sheep, lot-fed sheep maintained on diets comprising various combinations of silage and grain, and sheep simultaneously grazing pastures with cattle to explore the diversity of cSTEC serotypes capable of colonizing healthy sheep. A total of 67 cSTEC serotypes were isolated, of which 21 (31.3%), mainly isolated from lambs, have not been reported. Of the total isolations, 58 (86.6%) were different from cSTEC serotypes isolated from a recent study of longitudinally sampled healthy Australian cattle (M. Hornitzky, B. A. Vanselow, K. Walker, K. A. Bettelheim, B. Corney, P. Gill, G. Bailey, and S. P. Djordjevic, Appl. Environ. Microbiol.
68:
6439-6445, 2002). Our data suggest that cSTEC serotypes O5:H
−
, O75:H8, O91:H
−
, O123:H
−
, and O128:H2 are well adapted to colonizing the ovine gastrointestinal tract, since they were the most prevalent serotypes isolated from both pasture-fed and lot-fed sheep. Collectively, our data show that Australian sheep are colonized by diverse cSTEC serotypes that are rarely isolated from healthy Australian cattle.
Lipid Accumulation, Lipid Body Formation, and Acyl Coenzyme A Oxidases of the Yeast
Yarrowia lipolytica
Authors: Mlíčková Kateřina , Roux Emeline , Athenstaedt Karin , d'Andrea Sabine , Daum Günther , Chardot Thierry , Nicaud Jean-Marc 
Published: July 2004

ABSTRACT

Yarrowia lipolytica
contains five acyl-coenzyme A oxidases (Aox), encoded by the
POX1
to
POX5
genes, that catalyze the limiting step of peroxisomal β-oxidation. In this study, we analyzed morphological changes of
Y. lipolytica
growing in an oleic acid medium and the effect of
POX
deletions on lipid accumulation. Protrusions involved in the uptake of lipid droplets (LDs) from the medium were seen in electron micrographs of the surfaces of wild-type cells grown on oleic acid. The number of protrusions and surface-bound LDs increased during growth, but the sizes of the LDs decreased. The sizes of intracellular lipid bodies (LBs) and their composition depended on the
POX
genotype. Only a few, small, intracellular LBs were observed in the mutant expressing only Aox4p (Δ
pox2
Δ
pox3
Δ
pox5
), but strains expressing either Aox3p or both Aox3p and Aox4p had the same number of LBs as did the wild type. In contrast, strains expressing either Aox2p or both Aox2p and Aox4p formed fewer, but larger, LBs than did the wild type. The size of the LBs increased proportionately with the amount of triacylglycerols in the LBs of the mutants. In summary, Aox2p expression regulates the size of cellular triacylglycerol pools and the size and number of LBs in which these fatty acids accumulate.
Biodegradation of All Stereoisomers of the EDTA Substitute Iminodisuccinate by
Agrobacterium tumefaciens
BY6 Requires an Epimerase and a Stereoselective C-N Lyase
Authors: Cokesa Z̆eljko , Knackmuss Hans-Joachim , Rieger Paul-Gerhard 
Published: July 2004

ABSTRACT

Biodegradation tests according to Organization for Economic Cooperation and Development standard 301F (manometric respirometry test) with technical iminodisuccinate (IDS) revealed ready biodegradability for all stereoisomers of IDS. The IDS-degrading strain
Agrobacterium tumefaciens
BY6 was isolated from activated sludge. The strain was able to grow on each IDS isomer as well as on Fe
2+
-, Mg
2+
-, and Ca
2+
-IDS complexes as the sole carbon, nitrogen, and energy source. In contrast, biodegradation of and growth on Mn
2+
-IDS were rather scant and very slow on Cu
2+
-IDS. Growth and turnover experiments with
A. tumefaciens
BY6 indicated that the isomer R,S-IDS is the preferred substrate. The IDS-degrading enzyme system isolated from this organism consists of an IDS-epimerase and a C-N lyase. The C-N lyase is stereospecific for the cleavage of R,S-IDS, generating
d
-aspartic acid and fumaric acid. The decisive enzyme for S,S-IDS and R,R-IDS degradation is the epimerase. It transforms S,S-IDS and R,R-IDS into R,S-IDS. Both enzymes do not require any cofactors. The two enzymes were purified and characterized, and the N-termini were sequenced. The purified lyase and also the epimerase catalyzed the transformation of alkaline earth metal-IDS complexes, while heavy metal-IDS complexes were transformed rather slowly or not at all. The observed mechanism for the complete mineralization of all IDS isomers involving an epimerase offers an interesting possibility of funneling all stereoisomers into a catabolic pathway initiated by a stereoselective lyase.
Temporal and Spatial Profiles of Chitinase Expression by Norway Spruce in Response to Bark Colonization by
Heterobasidion annosum
Authors: Hietala Ari M. , Kvaalen Harald , Schmidt Axel , Jøhnk Nina , Solheim Halvor , Fossdal Carl G. 
Published: July 2004

ABSTRACT

Pathogen colonization and transcript levels of three host chitinases, putatively representing classes I, II, and IV, were monitored with real-time PCR after wounding and bark infection by
Heterobasidion annosum
in 32-year-old trees of Norway spruce (
Picea abies
) with low (clone 409) or high (clone 589) resistance to this pathogen. Three days after inoculation, comparable colonization levels were observed in both clones in the area immediately adjacent to inoculation. At 14 days after infection, pathogen colonization was restricted to the area immediately adjacent to the site of inoculation for clone 589 but had progressed further into the host tissue in clone 409. Transcript levels of the class II and IV chitinases increased after wounding or inoculation, but the transcript level of the class I chitinase declined after these treatments. Transcript levels of the class II and class IV chitinases were higher in areas immediately adjacent to the inoculation site in clone 589 than in similar sites in clone 409 3 days after inoculation. This difference was even more pronounced 2 to 6 mm away from the inoculation point, where no infection was yet established, and suggests that the clones differ in the rate of chitinase-related signal perception or transduction. At 14 days after inoculation, these transcript levels were higher in clone 409 than in clone 589, suggesting that the massive upregulation of class II and IV chitinases after the establishment of infection comes too late to reduce or prevent pathogen colonization.
Relationship between
gyrA
Mutations and Quinolone Resistance in
Flavobacterium psychrophilum
Isolates
Authors: Izumi Shotaro , Aranishi Futoshi 
Published: July 2004

ABSTRACT

Flavobacterium psychrophilum
is the causative agent of the fish diseases called bacterial cold-water disease and rainbow trout fry syndrome. It has been reported that some isolates of
F. psychrophilum
are resistant to quinolones; however, the mechanism of this quinolone resistance has been unexplained. In this study, we examined the quinolone susceptibility patterns of 27
F. psychrophilum
strains isolated in Japan and the United States. Out of 27 isolates, 14 were resistant to both nalidixic acid (NA) and oxolinic acid (OXA), and the others were susceptible to NA and OXA. When amino acid sequences deduced from
gyrA
nucleotide sequences of all isolates tested were analyzed, two amino acid substitutions (a threonine residue replaced by an alanine or isoleucine residue in position 83 of GyrA [
Escherichia coli
numbering] and an aspartic acid residue replaced by a tyrosine residue in position 87) were observed in the 14 quinolone-resistant isolates. These results strongly suggest that, as in other gram-negative bacteria, DNA gyrase is an important target for quinolones in
F. psychrophilum
.
Genetic Characterization and Transmission Cycles of
Cryptosporidium
Species Isolated from Humans in New Zealand
Authors: Learmonth James J. , Ionas George , Ebbett Kim A. , Kwan Errol S. 
Published: July 2004

ABSTRACT

Little is known about the genetic characteristics, distribution, and transmission cycles of
Cryptosporidium
species that cause human disease in New Zealand. To address these questions, 423 fecal specimens containing
Cryptosporidium
oocysts and obtained from different regions were examined by the PCR-restriction fragment length polymorphism technique. Indeterminant results were resolved by DNA sequence analysis. Two regions supplied the majority of isolates: one rural and one urban. Overall,
Cryptosporidium hominis
accounted for 47% of the isolates, with the remaining 53% being the
C. parvum
bovine genotype. A difference, however, was observed between the
Cryptosporidium
species from rural and urban isolates, with
C. hominis
dominant in the urban region, whereas the
C. parvum
bovine genotype was prevalent in rural New Zealand. A shift in transmission cycles was detected between seasons, with an anthroponotic cycle in autumn and a zoonotic cycle in spring. A novel
Cryptosporidium
sp., which on DNA sequence analysis showed a close relationship with
C. canis
, was detected in two unrelated children from different regions, illustrating the genetic diversity within this genus.
Toxic and Nontoxic
Microcystis
Colonies in Natural Populations Can Be Differentiated on the Basis of rRNA Gene Internal Transcribed Spacer Diversity
Authors: Janse Ingmar , Kardinaal W. Edwin A. , Meima Marion , Fastner Jutta , Visser Petra M. , Zwart Gabriel 
Published: July 2004

ABSTRACT

Assessing
and predicting bloom dynamics and toxin production by
Microcystis
requires analysis of toxic and nontoxic
Microcystis
genotypes in natural communities. We show that
genetic differentiation of
Microcystis
colonies based on rRNA
internal transcribed spacer (ITS) sequences provides an adequate basis
for recognition of microcystin producers. Consequently, ecological
studies of toxic and nontoxic cyanobacteria are now possible through
studies of rRNA ITS genotypic diversity in isolated cultures or
colonies and in natural communities. A total of 107
Microcystis
colonies were isolated from 15 lakes in Europe and
Morocco, the presence of microcystins in each colony was examined by
matrix-assisted laser desorption ionization-time of flight mass
spectrometry (MALDI-TOF MS), and they were grouped by rRNA ITS
denaturing gradient gel electrophoresis (DGGE) typing. Based on DGGE
analysis of amplified ITSa and ITSc fragments, yielding supplementary
resolution (I. Janse et al., Appl. Environ. Microbiol.
69:
6634-6643, 2003), the colonies could be differentiated into
59 classes. Microcystin-producing and non-microcystin-producing
colonies ended up in different classes. Sequences from the rRNA ITS of
representative strains were congruent with the classification based on
DGGE and confirmed the recognition of microcystin producers on the
basis of rRNA ITS. The rRNA ITS sequences also confirmed
inconsistencies reported for
Microcystis
identification based
on morphology. There was no indication for geographical restriction of
strains, since identical sequences originated from geographically
distant lakes. About 28% of the analyzed colonies gave rise to
multiple bands in DGGE profiles, indicating either aggregation of
different colonies, or the occurrence of sequence differences between
multiple operons. Cyanobacterial community profiles from two Dutch
lakes from which colonies had been isolated showed different relative
abundances of genotypes between bloom stages and between the water
column and surface scum. Although not all bands in the community
profiles could be matched with isolated colonies, the profiles suggest
a dominance of nontoxic colonies, mainly later in the season and in
scums.
Control of
Listeria monocytogenes
in a Biofilm by Competitive-Exclusion Microorganisms
Authors: Zhao Tong , Doyle Michael P. , Zhao Ping 
Published: July 2004

ABSTRACT

Biofilms from drains in food processing facilities with a recent history of no detectable
Listeria monocytogenes
in floor drains were cultured for microorganisms producing antilisterial metabolites. A total of 413 microbial isolates were obtained from 12 drain biofilm samples and were assayed at 15 and 37°C for activities that were bactericidal or inhibitory to
L. monocytogenes
, by two agar plate assays. Twenty-one of 257 bacterial isolates and 3 of 156 yeast isolates had antilisterial activity. All 24 isolates which produced metabolites inhibitory to
L. monocytogenes
were assayed for antilisterial activity in coinoculated broth cultures containing tryptic soy broth with yeast extract (TSB-YE). A five-strain mixture of 10
3
CFU of
L. monocytogenes
/ml and 10
5
CFU of the candidate competitive-exclusion microorganism/ml was combined in TSB-YE and incubated at 37°C for 24 h, 15°C for 14 days, 8°C for 21 days, and 4°C for 28 days. Substantial inhibition of
L. monocytogenes
growth (4 to 5 log CFU/ml) was observed for nine bacterial isolates at 37°C, two at 15 and 8°C, and three at 4°C. The inhibitory isolates were identified as
Enterococcus durans
(six isolates),
Lactococcus lactis
subsp.
lactis
(two isolates), and
Lactobacillus plantarum
(one isolate). The anti-
L. monocytogenes
activity of these isolates was evaluated in biofilms of
L. monocytogenes
on stainless steel coupons at 37, 15, 8, and 4°C. Results revealed that two isolates (
E. durans
strain 152 and
L. lactis
subsp.
lactis
strain C-1-92) were highly inhibitory to
L. monocytogenes
(growth inhibition of >5 log
10
CFU of
L. monocytogenes
/cm
2
). These two bacterial isolates appear to be excellent competitive-exclusion candidates to control
L. monocytogenes
in biofilms at environmental temperatures of 4 to 37°C.
Characterization of
Salmonella enterica
Serovar Typhimurium from Marine Environments in Coastal Waters of Galicia (Spain)
Authors: Martinez-Urtaza Jaime , Liebana Ernesto , Garcia-Migura Lourdes , Perez-Piñeiro Pelayo , Saco Montserrat 
Published: July 2004

ABSTRACT

Twenty-three
Salmonella enterica
serovar Typhimurium isolates from marine environments were characterized by phage typing, pulsed-field gel electrophoresis (PFGE) analysis, plasmid analysis, and antibiotic resistance, and the distribution of the different types in the coastal waters were subsequently analyzed. Five phage types were identified among the isolates (PT41, PT135, PT99, DT104, and DT193). PT135 isolates were exclusively detected during the winter months from 1998 to 2000, whereas DT104 and PT41 isolates were detected exclusively in the summer months from 2000 to 2002. XbaI PFGE analysis revealed 9 PFGE types, and plasmid profiling identified 8 plasmid types (with 1 to 6 plasmids) among the isolates. Only three isolates presented multidrug resistance to antibiotics. Two DT104 isolates were resistant to 8 and 7 antibiotics (profiles ACCeFNaSSuT and ACeFNeSSuT), whereas a PT193 isolate presented resistance to 6 antibiotics (profile ACFSSu). In addition, four PT41 isolates were resistant to a single antibiotic. The detection of multidrug-resistant phage types DT104 and DT193 in shellfish emphasizes the importance of monitoring the presence of
Salmonella
in routine surveillance of live bivalve molluscs.