bluuebunny/crossref_metadata_2025_split huggingface dataset:
Curvularia
Haloperoxidase: Antimicrobial Activity and Potential Application as a Surface Disinfectant
Authors: Hansen Eva H. , Albertsen Line , Schäfer Thomas , Johansen Charlotte , Frisvad Jens C. , Molin Søren , Gram Lone 
Published: August 2003

ABSTRACT

A presumed antimicrobial enzyme system, the
Curvularia
haloperoxidase system, was examined with the aim of evaluating its potential as a sanitizing agent. In the presence of hydrogen peroxide,
Curvularia
haloperoxidase facilitates the oxidation of halides, such as chloride, bromide, and iodide, to antimicrobial compounds. The
Curvularia
haloperoxidase system caused several-log-unit reductions in counts of bacteria (
Pseudomonas
spp.,
Escherichia coli
,
Serratia marcescens
,
Aeromonas salmonicida
,
Shewanella putrefaciens
,
Staphylococcus epidermidis
, and
Listeria monocytogenes
), yeasts (
Candida
sp. and
Rhodotorula
sp.), and filamentous fungi (
Aspergillus niger
,
Aspergillus tubigensis
,
Aspergillus versicolor
,
Fusarium oxysporum
,
Penicillium chrysogenum
, and
Penicillium paxilli
) cultured in suspension. Also, bacteria adhering to the surfaces of contact lenses were killed. The numbers of
S. marcescens
and
S. epidermidis
cells adhering to contact lenses were reduced from 4.0 and 4.9 log CFU to 1.2 and 2.7 log CFU, respectively, after treatment with the
Curvularia
haloperoxidase system. The killing effect of the
Curvularia
haloperoxidase system was rapid, and 10
6
CFU of
E. coli
cells/ml were eliminated within 10 min of treatment. Furthermore, the antimicrobial effect was short lived, causing no antibacterial effect against
E. coli
10 min after the system was mixed. Bovine serum albumin (1%) and alginate (1%) inhibited the antimicrobial activity of the
Curvularia
haloperoxidase system, whereas glucose and Tween 20 did not affect its activity. In conclusion, the
Curvularia
haloperoxidase system is an effective sanitizing system and has the potential for a vast range of applications, for instance, for disinfection of contact lenses or medical devices.
Characterization of the Corrinoid Iron-Sulfur ProteinTetrachloroethene Reductive Dehalogenase of
Dehalobacterrestrictus
Authors: Maillard Julien , Schumacher Wolfram , Vazquez Francisco , Regeard Christophe , Hagen Wilfred R. , Holliger Christof 
Published: August 2003

ABSTRACT

The
membrane-bound tetrachloroethene reductive dehalogenase (PCE-RDase)
(PceA; EC 1.97.1.8), the terminal component of the respiratory chain of
Dehalobacter restrictus
, was purified 25-fold to apparent
electrophoretic homogeneity. Sodium dodecyl sulfate-polyacrylamide gel
electrophoresis revealed a single band with an apparent molecular mass
of 60 ± 1 kDa, whereas the native molecular mass was 71±
8 kDa according to size exclusion chromatography in the
presence of the detergent octyl-β-
d
-glucopyranoside.
The monomeric enzyme contained (per mol of the 60-kDa subunit) 1.0±
0.1 mol of cobalamin, 0.6 ± 0.02 mol of cobalt, 7.1±
0.6 mol of iron, and 5.8 ± 0.5 mol of acid-labile
sulfur. Purified PceA catalyzed the reductive dechlorination of
tetrachloroethene and trichloroethene to
cis
-1,2-dichloroethene with a specific activity of
250 ± 12 nkat/mg of protein. In addition, several
chloroethanes and tetrachloromethane caused methyl viologen oxidation
in the presence of PceA. The

K
m

values for
tetrachloroethene, trichloroethene, and methyl viologen were 20.4±
3.2, 23.7 ± 5.2, and 47 ± 10 μM,
respectively. The PceA exhibited the highest activity at pH 8.1 and was
oxygen sensitive, with a half-life of activity of 280 min upon exposure
to air. Based on the almost identical N-terminal amino acid sequences
of PceA of
Dehalobacter restrictus
,
Desulfitobacterium
hafniense
strain TCE1 (formerly
Desulfitobacterium
frappieri
strain TCE1), and
Desulfitobacterium hafniense
strain PCE-S (formerly
Desulfitobacterium frappieri
strain
PCE-S), the
pceA
genes of the first two organisms were cloned
and sequenced. Together with the
pceA
genes of
Desulfitobacterium hafniense
strains PCE-S and Y51, the
pceA
genes of
Desulfitobacterium hafniense
strain TCE1 and
Dehalobacter restrictus
form a coherent group
of reductive dehalogenases with almost 100% sequence identity.
Also, the
pceB
genes, which may code for a membrane anchor
protein of PceA, and the intergenic regions of
Dehalobacter
restrictus
and the three desulfitobacteria had identical
sequences. Whereas the
cprB
(chlorophenol reductive
dehalogenase) genes of chlorophenol-dehalorespiring bacteria are always
located upstream of
cprA
, all
pceB
genes known so far
are located downstream of
pceA.
The possible consequences of
this feature for the annotation of putative reductive dehalogenase
genes are discussed, as are the sequence around the iron-sulfur cluster
binding motifs and the type of iron-sulfur clusters of the reductive
dehalogenases of
Dehalobacter restrictus
and
Desulfitobacterium dehalogenans
identified by electron
paramagnetic resonance
spectroscopy.
Genetic Diversity and Temporal Variation in the Cyanophage Community Infecting Marine
Synechococcus
Species in Rhode Island's Coastal Waters
Authors: Marston Marcia F. , Sallee Jennifer L. 
Published: August 2003

ABSTRACT

The cyanophage community in Rhode Island's coastal waters is genetically diverse and dynamic. Cyanophage abundance ranged from over 10
4
phage ml
−1
in the summer months to less then 10
2
phage ml
−1
during the winter months. Thirty-six distinct cyanomyovirus g20 genotypes were identified over a 3-year sampling period; however, only one to nine g20 genotypes were detected at any one sampling date. Phylogenetic analyses of g20 sequences revealed that the Rhode Island cyanomyoviral isolates fall into three main clades and are closely related to other known viral isolates of
Synechococcus
spp. Extinction dilution enrichment followed by host range tests and PCR restriction fragment length polymorphism analysis was used to detect changes in the relative abundance of cyanophage types in June, July, and August 2002. Temporal changes in both the overall composition of the cyanophage community and the relative abundance of specific cyanophage g20 genotypes were observed. In some seawater samples, the g20 gene from over 50% of isolated cyanophages could not be amplified by using the PCR primer pairs specific for cyanomyoviruses, which suggested that cyanophages in other viral families (e.g.,
Podoviridae
or
Siphoviridae
) may be important components of the Rhode Island cyanophage community.
Effect of Incubation Temperature on Isolation of
Campylobacter jejuni
Genotypes from Foodstuffs Enriched in Preston Broth
Authors: Scates Pam , Moran Lynn , Madden Robert H. 
Published: August 2003

ABSTRACT

Preston broth and agar incubated at either 37 or 42°C have been widely used to isolate campylobacters from foodstuffs. The consequences of using either incubation temperature were investigated. Retail packs of raw chicken (
n
= 24) and raw lamb liver (
n
= 30) were purchased. Samples were incubated in Preston broth at 37 and 42°C and then streaked onto Preston agar and incubated as before. Two
Campylobacter
isolates per treatment were characterized. Poultry isolates were genotyped by random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE), and flagellin PCR-restriction fragment length polymorphism, and lamb isolates were genotyped by RAPD only. In total, 96% of the poultry and 73% of the lamb samples yielded campylobacters. The lamb isolates were all
Campylobacter jejuni
, as were 96% of the poultry isolates, with the remainder being
Campylobacter lari
. The incubation temperature had no significant effect on the number of positive samples or on the species isolated. However, genotyping of the
C. jejuni
isolates revealed profound differences in the types obtained. Overall (from poultry and lamb), the use of a single incubation temperature, 37°C, gave 56% of the total number of RAPD
C. jejuni
genotypes, and hence, 44% remained undetected. The effect was especially marked in the poultry samples, where incubation at 37°C gave 47% of the PFGE genotypes but 53% were exclusively recovered after incubation at 42°C. Thus, the incubation temperature of Preston media selects for certain genotypes of
C. jejuni
, and to detect the widest range, samples should be incubated at both 37 and 42°C. Conversely, genotyping results arising from the use of a single incubation temperature should be interpreted with caution.
PCR-Restriction Fragment Length Polymorphism Method for Detection of
Cyclospora cayetanensis
in Environmental Waters without Microscopic Confirmation
Authors: Shields Joan M. , Olson Betty H. 
Published: August 2003

ABSTRACT

We developed an alternative nested-PCR-restriction fragment length polymorphism (RFLP) protocol for the detection of
Cyclospora cayetanensis
in environmental samples that obviates the need for microscopic examination. The RFLP method, with the restriction enzyme
Alu
I, differentiates the amplified target sequence from
C
.
cayetanensis
from those that may cross-react. This new protocol was used to reexamine a subset (121 of 180) of surface water samples. Samples previously positive when the CYCF3E and CYCR4B primers (33) and RFLP with
Mnl
I (20) were used were also PCR positive with the new primers; however, they were RFLP negative. We verified, by sequencing these amplicons, that while two were most likely other
Cyclospora
species, they were not
C
.
cayetanensis
. We can detect as few as one oocyst seeded into an autoclaved pellet flocculated from 10 liters of surface water. This new protocol should be of great use for environmental microbiologists and public health laboratories.
virF-PositiveYersinia pseudotuberculosisandYersinia enterocoliticaFound in Migratory Birds in Sweden
Authors: Niskanen Taina , Waldenström Jonas , Fredriksson-Ahomaa Maria , Olsen Björn , Korkeala Hannu 
Published: August 2003

ABSTRACTDuring spring and autumn migrations, 468 fecal samples from 57 different species of migratory birds were collected in Sweden. In total,Yersiniaspp. were isolated from 12.8% of collected samples. The most commonly found species wasYersinia enterocolitica, which was isolated from 5.6% of all collected samples, followed byY. intermedia(3.8%),Y. frederiksenii(3.0%),Y. kristensenii(0.9%),Y. pseudotuberculosis(0.6%), andY. rohdei(0.4%). The pathogenic,virF-positiveY. pseudotuberculosisstrains were recovered from three thrushes. These strains belonged to the same bioserotype, 1/O:2, but had two different profiles as determined by pulsed-field gel electrophoresis withNotI andSpeI enzymes. In addition, 10Y. enterocoliticastrains, all from barnacle geese, belonged to bioserotype 3/O:3, which is associated with human disease. Two of the strains were pathogenic, carrying thevirFgene on their plasmids. All pathogenicY. pseudotuberculosisandY. enterocoliticastrains were recovered during the spring, and as the birds were caught during active migration they likely became infected at an earlier stage of the migration, thus potentially transporting these bacterial pathogens over long geographical distances.
Alternative Splicing of Transcripts from
crtI
and
crtYB
Genes of
Xanthophyllomyces dendrorhous
Authors: Lodato P. , Alcaino J. , Barahona S. , Retamales P. , Cifuentes V. 
Published: August 2003

ABSTRACT

Xanthophyllomyces dendrorhous
is one of the relevant sources of the carotenoid astaxanthin. In this paper, we describe for the first time cloning of unexpected cDNAs obtained from the
crtI
and
crtYB
genes of
X. dendrorhous
strain UCD 67-385. The cDNA of the
crtI
gene conserves 80 bp of the first intron, while the cDNA of the
crtYB
gene conserves 55 bp of the first intron and lacks 111 bp of the second exon. The
crtI
and
crtYB
RNAs could be spliced in alternative splice sites, which produced alternative transcripts which could not be translated to active CRTI and CRTYB proteins since they had numerous stop codons in their sequences. The ratio of mature mRNA to alternative mRNA for the
crtI
gene decreased as a function of the age of the culture, while the cellular content of carotenoids increased. It is possible that splicing to mature or alternative transcripts could regulate the cellular concentrations of phytoene desaturase and phytoene synthase-lycopene cyclase proteins, depending on the physiological or environmental conditions.
Growth of
Rhodosporidium toruloides
Strain DBVPG 6662 on Dibenzothiophene Crystals and Orimulsion
Authors: Baldi Franco , Pepi Milva , Fava Fabio 
Published: August 2003

ABSTRACT

Strains DBVPG 6662 and DBVPG 6739 of
Rhodosporidium toruloides
, a basidiomycete yeast, grew on thiosulfate as a sulfur source and glucose (2 g liter
−1
or 10.75 mM) as a carbon source. DBVPG 6662 has a defective sulfate transport system, whereas DBVPG 6739 barely grew on sulfate. They were compared for the ability to use dibenzothiophene (DBT) and related organic sulfur compounds as sulfur sources. In the presence of glucose as a carbon source and DBT as a sulfur source, strain DBVPG 6662 grew better than DBVPG 6739. In the presence of thiosulfate as a sulfur source, the two yeast strains did not use DBT, DBT-sulfone, benzenesulfonic acid, biphenyl, and fluorene. When the two strains were grown in the presence of glucose, strain DBVPG 6662 transformed 27% of the DBT present (10 μM) at a rate of 0.023 μmol liter
−1
h
−1
in 36 h. Traces of 2,2′-dihydroxylated biphenyl were transiently accumulated under these conditions. When the same strain was grown on glucose in the presence of a higher concentration of DBT (0.5 g liter
−1
), mainly in an insoluble form, the whole surface of the DBT crystals was colonized by a thick mycelium. This adherent structure was imaged by confocal microscopy with fluorescent concanavalin A, a lectin that specifically binds glucose and mannose residues. When DBVPG 6662 was grown on glucose in the presence of a commercial emulsion of bitumen, i.e., orimulsion, 68% of the benzo- and dibenzothiophenes and DBTs was removed after 15 days of incubation. The fungus adhered by hyphae to orimulsion droplets. When cultivated in the presence of commercial emulsifier-free fuel oil containing alkylated benzothiophenes and DBTs and having a composition similar to that of orimulsion, strain DBVPG 6662 removed only 11% of the total organic sulfur that occurs in the medium and did not adhere to the oil droplets. These results indicate that strain DBVPG 6662 is able to utilize the organic sulfur of DBT and a large variety of thiophenic compounds that occur extensively in commercial fuel oils by physically adhering to the organic sulfur source.
Rapid Detection of Meat Spoilage by Measuring Volatile Organic Compounds by Using Proton Transfer Reaction Mass Spectrometry
Authors: Mayr D. , Margesin R. , Klingsbichel E. , Hartungen E. , Jenewein D. , Schinner F. , Märk T. D. 
Published: August 2003

ABSTRACT

The evolution of the microbial spoilage population for air- and vacuum-packaged meat (beef and pork) stored at 4°C was investigated over 11 days. We monitored the viable counts (mesophilic total aerobic bacteria,
Pseudomonas
spp.,
Enterobacteriaceae
, lactic acid bacteria, and
Enterococcus
spp.) by the microbiological standard technique and by measuring the emission of volatile organic compounds (VOCs) with the recently developed proton transfer reaction mass spectrometry system. Storage time, packaging type, and meat type had statistically significant (
P
< 0.05) effects on the development of the bacterial numbers. The concentrations of many of the measured VOCs, e.g., sulfur compounds, largely increased over the storage time. We also observed a large difference in the emissions between vacuum- and air-packaged meat. We found statistically significant strong correlations (up to 99%) between some of the VOCs and the bacterial contamination. The concentrations of these VOCs increased linearly with the bacterial numbers. This study is a first step toward replacing the time-consuming plate counting by fast headspace air measurements, where the bacterial spoilage can be determined within minutes instead of days.
Photobactin: a Catechol Siderophore Produced by
Photorhabdus luminescens
, an Entomopathogen Mutually Associated with
Heterorhabditis bacteriophora
NC1 Nematodes
Authors: Ciche Todd A. , Blackburn Michael , Carney John R. , Ensign Jerald C. 
Published: August 2003

ABSTRACT

The nematode
Heterorhabditis bacteriophora
transmits a monoculture of
Photorhabdus luminescens
bacteria to insect hosts, where it requires the bacteria for efficient insect pathogenicity and as a substrate for growth and reproduction. Siderophore production was implicated as being involved in the symbiosis because an
ngrA
mutant inadequate for supporting nematode growth and reproduction was also deficient in producing siderophore activity and
ngrA
is homologous to a siderophore biosynthetic gene,
entD
. The role of the siderophore in the symbiosis with the nematode was determined by isolating and characterizing a mini-Tn
5
-induced mutant, NS414, producing no detectable siderophore activity. This mutant, being defective for growth in iron-depleted medium, was normal in supporting nematode growth and reproduction, in transmission by the dauer juvenile nematode, and in insect pathogenicity. The mini-Tn
5
transposon was inserted into
phbH
; whose protein product is a putative peptidyl carrier protein homologous to the nonribosomal peptide synthetase VibF of
Vibrio cholerae
. Other putative siderophore biosynthetic and transport genes flanking
phbH
were characterized. The catecholate siderophore was purified, its structure was determined to be 2-(2,3-dihydroxyphenyl)-5-methyl-4,5-dihydro-oxazole-4-carboxylic acid [4-(2,3-dihydroxybenzoylamino)-butyl]-amide, and it was given the generic name photobactin. Antibiotic activity was detected with purified photobactin, indicating that the siderophore may contribute to antibiosis of the insect cadaver. These results eliminate the lack of siderophore activity as the cause for the inadequacy of the
ngrA
mutant in supporting nematode growth and reproduction.
Occurrence of
Escherichia coli
and Enterococci in
Cladophora
(Chlorophyta) in Nearshore Water and Beach Sand of Lake Michigan
Authors: Whitman Richard L. , Shively Dawn A. , Pawlik Heather , Nevers Meredith B. , Byappanahalli Muruleedhara N. 
Published: August 2003

ABSTRACT

Each summer, the nuisance green alga
Cladophora
(mostly
Cladophora glomerata
) amasses along Lake Michigan beaches, creating nearshore anoxia and unsightly, malodorous mats that can attract problem animals and detract from visitor enjoyment. Traditionally, elevated counts of
Escherichia coli
are presumed to indicate the presence of sewage, mostly derived from nearby point sources. The relationship between fecal indicator bacteria and
Cladophora
remains essentially unstudied. This investigation describes the local and regional density of
Escherichia coli
and enterococci in
Cladophora
mats along beaches in the four states (Wisconsin, Illinois, Indiana, and Michigan) bordering Lake Michigan. Samples of
Cladophora
strands collected from 10 beaches (
n
= 41) were assayed for concentrations of
E. coli
and enterococci during the summer of 2002. Both
E. coli
and enterococci were ubiquitous (up to 97% occurrence), with overall log mean densities (± standard errors) of 5.3 (± 4.8) and 4.8 (± 4.5) per g (dry weight).
E. coli
and enterococci were strongly correlated in southern Lake Michigan beaches (
P
< 0.001,
R
2
= 0.73,
n
= 17) but not in northern beaches (
P
= 0.892,
n
= 16). Both
E. coli
and enterococci survived for over 6 months in sun-dried
Cladophora
mats stored at 4°C; the residual bacteria in the dried alga readily grew upon rehydration. These findings suggest that
Cladophora
amassing along the beaches of Lake Michigan may be an important environmental source of indicator bacteria and call into question the reliability of
E. coli
and enterococci as indicators of water quality for freshwater recreational beaches.
Intraspecies Polymorphism of
Cryptosporidium parvum
Revealed by PCR-Restriction Fragment Length Polymorphism (RFLP) and RFLP-Single-Strand Conformational Polymorphism Analyses
Authors: Wu Zhiliang , Nagano Isao , Boonmars Thidarut , Nakada Takumi , Takahashi Yuzo 
Published: August 2003

ABSTRACT

A glycoprotein (Cpgp40/15)-encoding gene of
Cryptosporidium parvum
was analyzed to reveal intraspecies polymorphism within
C
.
parvum
isolates. Forty-one isolates were collected from different geographical origins (Japan, Italy, and Nepal) and hosts (humans, calves, and a goat). These isolates were characterized by means of DNA sequencing, PCR-restriction fragment length polymorphism (PCR-RFLP), and RFLP-single-strand conformational polymorphism (RFLP-SSCP) analyses of the gene for Cpgp40/15. The sequence analysis indicated that there was DNA polymorphism between genotype I and II, as well as within genotype I, isolates. The DNA and amino acid sequence identities between genotypes I and II differed, depending on the isolates, ranging from 73.3 to 82.9% and 62.4 to 80.1%, respectively. Those among genotype I isolates differed, depending on the isolates, ranging from 69.0 to 85.4% and 54.8 to 79.2%, respectively. Because of the high resolution generated by PCR-RFLP and RFLP-SSCP, the isolates of genotype I could be subtyped as genotypes Ia1, Ia2, Ib, and Ie. The isolates of genotype II could be subtyped as genotypes IIa, IIb, and IIc. The isolates from calves, a goat, and one Japanese human were identified as genotype II. Within genotype II, the isolates from Japan were identified as genotype IIa, those from calves in Italy were identified as genotype IIb, and the goat isolate was identified as genotype IIc. All of the genotype I isolates were from humans. The Japanese isolate (code no. HJ3) and all of the Nepalese isolates were identified as genotypes Ia1 and Ia2, respectively. The Italian isolates were identified as genotype Ib, and the Japanese isolate (code no. HJ2) was identified as genotype Ie. Thus, the PCR-RFLP-SSCP analysis of this glycoprotein Cpgp40/15 gene generated a high resolution that has not been achieved by previous methods of genotypic differentiation of
C
.
parvum
.
Metabolic Engineering of Ammonium Assimilation in Xylose-Fermenting
Saccharomyces cerevisiae
Improves Ethanol Production
Authors: Roca Christophe , Nielsen Jens , Olsson Lisbeth 
Published: August 2003

ABSTRACT

Cofactor imbalance impedes xylose assimilation in
Saccharomyces cerevisiae
that has been metabolically engineered for xylose utilization. To improve cofactor use, we modified ammonia assimilation in recombinant
S. cerevisiae
by deleting
GDH1
, which encodes an NADPH-dependent glutamate dehydrogenase, and by overexpressing either
GDH2
, which encodes an NADH-dependent glutamate dehydrogenase, or
GLT1
and
GLN1
, which encode the GS-GOGAT complex. Overexpression of
GDH2
increased ethanol yield from 0.43 to 0.51 mol of carbon (Cmol) Cmol
−1
, mainly by reducing xylitol excretion by 44%. Overexpression of the GS-GOGAT complex did not improve conversion of xylose to ethanol during batch cultivation, but it increased ethanol yield by 16% in carbon-limited continuous cultivation at a low dilution rate.