bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Lansoprazole and Amoxicillin on Uptake of [
14
C]Clarithromycin into Gastric Tissue in Rats
Authors: Endo Hiromi , Yoshida Hideo , Ohmi Naoko , Higuchi Shohei
Published: July 2002

Triple therapy consisting of clarithromycin (CLR), lansoprazole (LPZ), and amoxicillin (AMZ) is effective as eradication therapy for patients with peptic ulcer disease and
Helicobacter pylori
infection. We evaluated the effects of LPZ and AMZ on the uptake of [
14
C]CLR into the gastric tissue of rats. After administration of [
14
C]CLR alone or in combination with LPZ and AMZ, the distributions of [
14
C]CLR in the main organs and gastrointestinal tissues were compared. LPZ and AMZ had no effect on the distribution of [
14
C]CLR in any tissue except gastric tissue. The concentration of radioactivity in gastric tissue was several times higher when [
14
C]CLR was administered orally together with LPZ than when it was administered alone. The gastric emptying of [
14
C]CLR became smaller in the case of the coadministration of LPZ. AMZ had no apparent influence on the disposition of [
14
C]CLR. After the intravenous administration of [
14
C]CLR, no effects of drug coadministration were evident. In vitro uptake of [
14
C]CLR into gastric tissue was enhanced in the case of a high-pH environment. The uptake was not influenced by the concurrent presence of LPZ and AMZ. These results suggest that the penetration of [
14
C]CLR possibly depends on elevated gastric pH, as gastric acid secretion was inhibited by LPZ, and this may be a primary factor in explaining why the concentration of [
14
C]CLR at the target site, gastric tissue, was enhanced by the coadministration of LPZ.
Dynamic and Heterogeneous Mutations to Fluconazole Resistance in
Cryptococcus neoformans
Authors: Xu Jianping , Onyewu Chiatogu , Yoell Heather J. , Ali Rabia Y. , Vilgalys Rytas J. , Mitchell Thomas G.
Published: July 2002

Infections with the human pathogenic basidiomycetous yeast
Cryptococcus neoformans
are often treated with fluconazole. Resistance to this antifungal agent has been reported. This study investigated the patterns of mutation to fluconazole resistance in
C. neoformans
in vitro. The MIC of fluconazole was measured for 21 strains of
C. neoformans
. The MICs for these 21 strains differed (0.25 to 4.0 μg/ml), but the strains were selected for this study because they exhibited no growth on plates of yeast morphology agar (YMA) containing 8 μg of fluconazole per ml. To determine their mutation rates, six independent cultures from a single original colony were established for each of the 21 strains. Each culture was then spread densely on a YMA plate with 8 μg of fluconazole per ml. A random set of putative mutants was subcultured, and the MIC of fluconazole was determined for each mutant. The 21 strains evinced significant heterogeneity in their mutation rates. The MICs of the putative mutants ranged widely, from their original MIC to 64 μg of fluconazole per ml. However, for this set of 21 strains, there was no significant correlation between the original MIC for a strain and the mutation rate of that strain; the MIC for the mutant could not be predicted from the original MIC. These results suggest that dynamic and heterogeneous mutational processes are involved in generating fluconazole resistance in
C. neoformans
.
Antibiotic Susceptibilities of Genetically Characterized
Streptococcus milleri
Group Strains
Authors: Tracy Michael , Wanahita Anna , Shuhatovich Yevgeny , Goldsmith Elizabeth A. , Clarridge Jill E. , Musher Daniel M.
Published: July 2002

Previous studies of the antibiotic susceptibility of
Streptococcus milleri
group organisms have distinguished among species by using phenotypic techniques. Using 44 isolates that were speciated by 16S rRNA gene sequencing, we studied the MICs and minimum bactericidal concentrations of penicillin, ampicillin, ceftriaxone, and clindamycin for
Streptococcus intermedius, Streptococcus constellatus,
and
Streptococcus anginosus
. None of the organisms was resistant to beta-lactam antibiotics, although a few isolates were intermediately resistant; one strain of
S. anginosus
was tolerant to ampicillin, and another was tolerant to ceftriaxone. Six isolates were resistant to clindamycin, with representation from each of the three species. Relatively small differences in antibiotic susceptibilities among species of the
S. milleri
group show that speciation is unlikely to be important in selecting an antibiotic to treat infection caused by one of these isolates.
CENTA as a Chromogenic Substrate for Studying β-Lactamases
Authors: Bebrone Carine , Moali Catherine , Mahy Florence , Rival Sandrine , Docquier Jean Denis , Rossolini Gian Maria , Fastrez Jacques , Pratt Rex F. , Frère Jean-Marie , Galleni Moreno
Published: July 2002

CENTA, a chromogenic cephalosporin, is readily hydrolyzed by β-lactamases of all classes except for the
Aeromonas hydrophila
metalloenzyme. Although it cannot practically be used for the detection of β-lactamase-producing strains on agar plates, it should be quite useful for kinetic studies and the detection of the enzymes in crude extracts and chromatographic fractions.
Potent In Vitro Antimalarial Activity of Metacycloprodigiosin Isolated fromStreptomycesspectabilisBCC 4785
Authors: Isaka Masahiko , Jaturapat Amonlaya , Kramyu Jarin , Tanticharoen Morakot , Thebtaranonth Yodhathai
Published: July 2002

Bioassay-guided fractionation of the extract from the fermentation broth ofStreptomycesspectabilisBCC 4785 led to the isolation of three principle antimalarial agents, metacycloprodigiosin, bafilomycin A1, and spectinabilin. Metacycloprodigiosin exhibited potent in vitro activity againstPlasmodiumfalciparumK1, with a 50% inhibitory concentration of 0.0050 ± 0.0010 μg/ml, while its cytotoxicity was much weaker.
Effects of Specific Antibodies against
Streptococcus pneumoniae
on Pharmacodynamic Parameters of β-Lactams in a Mouse Sepsis Model
Authors: Casal J. , Aguilar L. , Jado I. , Yuste J. , Giménez M. J. , Prieto J. , Fenoll A.
Published: July 2002

A dose-ranging study to investigate the in vivo effects of the presence of specific antibodies on the efficacy of β-lactam treatment of sepsis caused by
Streptococcus pneumoniae
(non-β-lactam-susceptible serotype 6B isolate) was performed with a BALB/c mouse model. Hyperimmune serum was obtained from mice immunized with the heat-inactivated strain. The rate of mortality was 100% in nontreated animals in the absence of specific antibodies. A single injection of a one-half or one-quarter dilution of hyperimmune serum produced 60 to 40% survival rates. In the absence of specific antibodies, the minimal effective doses of amoxicillin and cefotaxime that produced survival rates of 100 and 80% were 25 and 50 mg/kg of body weight (three times a day for up to six doses), respectively. These doses produced times that the levels in serum remained above the MIC (Δ
T
> MICs) ≈30% of the dosing interval. When specific antibodies were present (by administration of a one-half or one-quarter dilution of hyperimmune serum), the minimal effective doses of the antibiotics were 3.12 and 6.25 mg/kg (≈8 times lower), with the Δ
T
> MICs being approximately 3 and 5% of the dosing interval for amoxicillin and cefotaxime, respectively. This in vivo combined pharmacodynamic effect offers possibilities that can be used to address penicillin resistance.
Comparative Antifungal Activities and Plasma Pharmacokinetics of Micafungin (FK463) against Disseminated Candidiasis and Invasive Pulmonary Aspergillosis in Persistently Neutropenic Rabbits
Authors: Petraitis Vidmantas , Petraitiene Ruta , Groll Andreas H. , Roussillon Kristin , Hemmings Melissa , Lyman Caron A. , Sein Tin , Bacher John , Bekersky Ihor , Walsh Thomas J.
Published: July 2002

Micafungin (FK463) is an echinocandin that demonstrates potent in vitro antifungal activities against
Candida
and
Aspergillus
species. However, little is known about its comparative antifungal activities in persistently neutropenic hosts. We therefore investigated the plasma micafungin pharmacokinetics and antifungal activities of micafungin against experimental disseminated candidiasis and invasive pulmonary aspergillosis in persistently neutropenic rabbits. The groups with disseminated candidiasis studied consisted of untreated controls (UCs); rabbits treated with desoxycholate amphotericin B (DAMB) at 1 mg/kg of body weight/day; or rabbits treated with micafungin at 0.25, 0.5, 1, and 2 mg/kg/day intravenously. Compared with the UCs, rabbits treated with micafungin or DAMB showed significant dosage-dependent clearance of
Candida albicans
from the liver, spleen, kidney, brain, eye, lung, and vena cava. These in vivo findings correlated with the results of in vitro time-kill assays that demonstrated that micafungin has concentration-dependent fungicidal activity. The groups with invasive pulmonary aspergillosis studied consisted of UCs; rabbits treated with DAMB; rabbits treated with liposomal amphotericin B (LAMB) at 5 mg/kg/day; and rabbits treated with micafungin at 0.5, 1, and 2 mg/kg/day. In comparison to the significant micafungin dosage-dependent reduction of the residual burden (in log CFU per gram) of
C. albicans
in tissue, micafungin-treated rabbits with invasive pulmonary aspergillosis had no reduction in the concentration of
Aspergillus fumigatus
in tissue. DAMB and LAMB significantly reduced the burdens of
C. albicans
and
A. fumigatus
in tissues (
P
< 0.01). Persistent galactomannan antigenemia in micafungin-treated rabbits correlated with the presence of an elevated burden of
A. fumigatus
in pulmonary tissue. By comparison, DAMB- and LAMB-treated animals had significantly reduced circulating galactomannan antigen levels. Despite a lack of clearance of
A. fumigatus
from the lungs, there was a significant improvement in the rate of survival (
P
< 0.001) and a reduction in the level of pulmonary infarction (
P
< 0.05) in micafungin-treated rabbits. In summary, micafungin demonstrated concentration-dependent and dosage-dependent clearance of
C. albicans
from persistently neutropenic rabbits with disseminated candidiasis but not of
A. fumigatus
from persistently neutropenic rabbits with invasive pulmonary aspergillosis.
Lack of Pharmacokinetic Interaction between the Oral Anti-Influenza Prodrug Oseltamivir and Aspirin
Authors: Oo Charles , Barrett Joanne , Dorr Albert , Liu Baolian , Ward Penelope
Published: July 2002

Twelve volunteers completed a two-sequence, three-way crossover study of a single 900-mg aspirin dose and multiple doses of 75 mg of oseltamivir in the absence and presence of 900 mg of aspirin. The plasma and urine results demonstrated no pharmacokinetic interaction between oseltamivir and aspirin.
Attachment of
Escherichia coli
O157:H7 to the Surfaces and Internal Structures of Apples as Detected by Confocal Scanning Laser Microscopy
Authors: Burnett Scott L. , Chen Jinru , Beuchat Larry R.
Published: July 2002

Confocal scanning laser microscopy (CSLM) was used to demonstrate the attachment of
Escherichia coli
O157:H7 transformed with a plasmid encoding for green fluorescent protein (GFP) to the surface and within the internal structures of nonwaxed Red Delicious cv. apples. Apples at 2 or 25°C were inoculated with an
E. coli
O157:H7 cell suspension at 2 or 25°C. The effect of a negative temperature differential (cold inoculum, warm apple), a positive differential (warm inoculum, cold apple), and no differential (warm inoculum, warm apple), in combination with a pressure differential (atmospheric versus 10,130 Pa), on the attachment and infiltration of cells was determined. CSLM stereo images of external surfaces of apples subjected to all combinations of test parameters showed preferential cellular attachment to discontinuities in the waxy cuticle on the surface and to damaged tissue surrounding puncture wounds, where the pathogen was observed at depths up to 70 μm below the skin surface. Attachment to lenticels was sporadic but was occasionally observed at depths of up to 40 μm. Infiltration through the floral tube and attachment to seeds, cartilaginous pericarp, and internal trichomes were observed in all apples examined, regardless of temperature differential during inoculation. The pressure differential had no effect on infiltration or attachment of
E. coli
O157:H7. Image analysis to count cells at various depths within tissues was used to quantitatively compare the extent of infiltration into various apple structures as well as the effects of the temperature differential. Puncture wounds harbored greater numbers of the pathogen at greater depths than did other sites examined. Attachment or infiltration of cells was greater on the intact skin and in lenticels, russet areas, and the floral tube of apples inoculated under a negative temperature differential compared to those inoculated under no temperature differential. The results suggest that
E. coli
O157:H7 attached to internal core structures or within tissues of apples may evade decontamination treatments. Interventions designed to deliver disinfectants to these locations or to remove viable cells of
E. coli
O157:H7 and other pathogens from apples by other means need to be developed and validated.
Effects of Agronomic Treatments on Structure and Function of Ammonia-Oxidizing Communities
Authors: Phillips Carol J. , Harris Dave , Dollhopf Sherry L. , Gross Katherine L. , Prosser James I. , Paul Eldor A.
Published: July 2002

The aim of this study was to determine the effects of different agricultural treatments and plant communities on the diversity of ammonia oxidizer populations in soil. Denaturing gradient gel electrophoresis (DGGE), coupled with specific oligonucleotide probing, was used to analyze 16S rRNA genes of ammonia oxidizers belonging to the β subgroup of the division
Proteobacteria
by use of DNA extracted from cultivated, successional, and native deciduous forest soils. Community profiles of the different soil types were compared with nitrification rates and most-probable-number (MPN) counts. Despite significant variation in measured nitrification rates among communities, there were no differences in the DGGE banding profiles of DNAs extracted from these soils. DGGE profiles of DNA extracted from samples of MPN incubations, cultivated at a range of ammonia concentrations, showed the presence of bands not amplified from directly extracted DNA.
Nitrosomonas
-like bands were seen in the MPN DNA but were not detected in the DNA extracted directly from soils. These bands were detected in some samples taken from MPN incubations carried out with medium containing 1,000 μg of NH
4
+
-N ml
−1
, to the exclusion of bands detected in the native DNA. Cell concentrations of ammonia oxidizers determined by MPN counts were between 10- and 100-fold lower than those determined by competitive PCR (cPCR). Although no differences were seen in ammonia oxidizer MPN counts from the different soil treatments, cPCR revealed higher numbers in fertilized soils. The use of a combination of traditional and molecular methods to investigate the activities and compositions of ammonia oxidizers in soil demonstrates differences in fine-scale compositions among treatments that may be associated with changes in population size and function.
Molecular Characterization of Irish
Salmonella enterica
Serotype Typhimurium: Detection of Class I Integrons and Assessment of Genetic Relationships by DNA Amplification Fingerprinting
Authors: Daly M. , Buckley J. , Power E. , O'Hare C. , Cormican M. , Cryan B. , Wall P. G. , Fanning S.
Published: July 2002

Salmonella enterica
is among the principal etiological agents of food-borne illness in humans. Increasing antimicrobial resistance in
S. enterica
is a cause for worldwide concern. There is concern at present in relation to the increasing incidence of human infection with antimicrobial agent-resistant strains of
S. enterica
serotype Typhimurium, in particular of phage type DT104. Integrons appear to play an important role in the dissemination of antimicrobial resistance genes in many
Enterobacteriaceae
including
S. enterica
. In this study the antimicrobial susceptibilities and phage types of 74 randomly collected strains of
S. enterica
serotype Typhimurium from the Cork region of southern Ireland, obtained from human, animal (clinical), and food sources, were determined. Each strain was examined for integrons and typed by DNA amplification fingerprinting (DAF). Phage type DT104 predominated (
n
= 48). Phage types DT104b (
n
= 3), -193 (
n
= 9), -195 (
n
= 6), -208 (
n
= 3), -204a (
n
= 2), PT U302 (
n
= 1), and two nontypeable strains accounted for the remainder. All
S. enterica
serotype Typhimurium DT104 strains were resistant to ampicillin, chloramphenicol, streptomycin, Sulfonamide Duplex, and tetracycline, and one strain was additionally resistant to trimethoprim. All DT104 strains but one were of a uniform DAF type (designated DAF-I) and showed a uniform pattern of integrons (designated IP-I). The DT104b and PT U302 strains also exhibited the same resistance phenotype, and both had the DAF-I and IP-I patterns. The DAF-I pattern was also observed in a single DT193 strain in which no integrons were detectable. Greater diversity of antibiograms and DAF and IP patterns among non-DT104 phage types was observed. These data indicate a remarkable degree of homogeneity at a molecular level among contemporary isolates of
S. enterica
serotype Typhimurium DT104 from animal, human, and food sources in this region.
Characterization of Fungal Biofilms within a Municipal Water Distribution System
Authors: Doggett M. Steven
Published: July 2002

Biofilms of a municipal water distribution system were characterized to assess the occurrence of fungi within surface matrixes. Densities of filamentous fungi ranged from 4.0 to 25.2 CFU cm
−2
, whereas yeast densities ranged from 0 to 8.9 CFU cm
−2
. Observations by scanning electron microscopy further suggested that spores, not hyphae or vegetative cells, comprised the primary source of viable propagules.
Role of

tfdC
I
D
I
E
I
F
I

and

tfdD
II
C
II
E
II
F
II

Gene Modules in Catabolism of 3-Chlorobenzoate by
Ralstonia eutropha
JMP134(pJP4)
Authors: Pérez-Pantoja D. , Guzmán L. , Manzano M. , Pieper D. H. , González B.
Published: July 2002

The enzymes chlorocatechol-1,2-dioxygenase, chloromuconate cycloisomerase, dienelactone hydrolase, and maleylacetate reductase allow
Ralstonia eutropha
JMP134(pJP4) to degrade chlorocatechols formed during growth in 2,4-dichlorophenoxyacetate or 3-chlorobenzoate (3-CB). There are two gene modules located in plasmid pJP4,

tfdC
I
D
I
E
I
F
I

(module I) and

tfdD
II
C
II
E
II
F
II

(module II), putatively encoding these enzymes. To assess the role of both
tfd
modules in the degradation of chloroaromatics, each module was cloned into the medium-copy-number plasmid vector pBBR1MCS-2 under the control of the
tfd
R regulatory gene. These constructs were introduced into
R. eutropha
JMP222 (a JMP134 derivative lacking pJP4) and
Pseudomonas putida
KT2442, two strains able to transform 3-CB into chlorocatechols. Specific activities in cell extracts of chlorocatechol-1,2-dioxygenase (
tfdC
), chloromuconate cycloisomerase (
tfdD
), and dienelactone hydrolase (
tfdE
) were 2 to 50 times higher for microorganisms containing module I compared to those containing module II. In contrast, a significantly (50-fold) higher activity of maleylacetate reductase (
tfdF
) was observed in cell extracts of microorganisms containing module II compared to module I. The
R. eutropha
JMP222 derivative containing

tfdR-tfdC
I
D
I
E
I
F
I

grew four times faster in liquid cultures with 3-CB as a sole carbon and energy source than in cultures containing

tfdR-tfdD
II
C
II
E
II
F
II

. In the case of
P. putida
KT2442, only the derivative containing module I was able to grow in liquid cultures of 3-CB. These results indicate that efficient degradation of 3-CB by
R. eutropha
JMP134(pJP4) requires the two
tfd
modules such that TfdCDE is likely supplied primarily by module I, while TfdF is likely supplied by module II.
Development and Evaluation of a Model Predicting the Survival of
Escherichia coli
O157:H7 NCTC 12900 in Homemade Eggplant Salad at Various Temperatures, pHs, and Oregano Essential Oil Concentrations
Authors: Skandamis Panagiotis N. , Nychas George-John E.
Published: July 2002

Homemade eggplant salad, a traditional Greek appetizer, was inoculated with
Escherichia coli
O157:H7 NCTC 12900 supplemented with different concentrations of oregano essential oil (0.0, 0.7, 1.4, and 2.1% [vol/wt]) and stored at different temperatures (0, 5, 10, and 15°C). The product's pH was adjusted to 4.0, 4.5, or 5.0 with lemon juice. For each combination of the environmental factors, the bacterial counts were modeled, using the Baranyi model, as a function of time to estimate the kinetic parameters of the pathogen. A reduction of more than 1 log unit in
E. coli
O157:H7 counts was observed in all cases, and the death rate depended on the pH, the storage temperature, and the essential oil concentration. Separate quadratic models were developed with natural logarithms of the shoulder period and death rate as estimated by the growth model, as a function of temperature, pH, and oregano essential oil concentrations. These were further used to predict the population of
E. coli
O157:H7 NCTC 12900 from other inoculated eggplant salads at random conditions of temperature, pH, and oregano oil concentration. The predicted values were compared with viable-count measurements for validation.
Fecal Shedding ofCampylobacterandArcobacterspp. in Dairy Cattle
Authors: Wesley I. V. , Wells S. J. , Harmon K. M. , Green A. , Schroeder-Tucker L. , Glover M. , Siddique I.
Published: July 2002

Campylobacter jejuni,Campylobacter coli, andArcobacterspp. were detected in feces of healthy dairy cows by highly specific multiplex-PCR assays. ForC. jejuni, at this one-time sampling, cows from 80.6% of farm operations (n= 31) and 37.7% of individual dairy cattle fecal samples (n= 2,085) were positive. Farm management factors were correlated with prevalence in herds in which >25% of cows were positive forC. jejuni. Statistical significance was set at aPof 0.20. Using these criteria, application of manure with broadcast spreaders (P= 0.17), feeding of whole cottonseed or hulls (P= 0.17) or alfalfa (P= 0.15), and accessibility of feed to birds (P= 0.17) were identified as possible risk factors forC. jejuniinfection.C. coliwas detected in at least one animal in 19.4% of operations and 1.8% of individual cows (n= 2,085). At the herd level, use of broadcaster spreaders was not a risk factor forC. coliinfection. ForArcobacter, cows from 71% of dairy operations (n= 31) and 14.3% of individual dairy cattle fecal samples (n= 1,682) were positive. At the herd level, forArcobacterspp., feeding of alfalfa (P= 0.11) and use of individual waterers (P= 0.19) were protective. This is the first description ofArcobacterspp. in clinically healthy dairy cattle and the first attempt to correlate their presence withC. jejuni.
Isolation and Expression of Lactate Dehydrogenase Genes fromRhizopus oryzae
Authors: Skory Christopher D.
Published: July 2002

Rhizopus oryzaeis used for industrial production of lactic acid, yet little is known about the genetics of this fungus. In this study I cloned two genes,ldhAandldhB, which code for NAD+-dependentl-lactate dehydrogenases (LDH) (EC1.1.1.27), from a lactic acid-producing strain ofR. oryzae. These genes are similar to each other and exhibit more than 90% nucleotide sequence identity and they contain no introns. This is the first description ofldhgenes in a fungus, and sequence comparisons revealed that these genes are distinct from previously isolated prokaryotic and eukaryoticldhgenes. Protein sequencing of the LDH isolated fromR. oryzaeduring lactic acid production confirmed thatldhAcodes for a 36-kDa protein that converts pyruvate to lactate. Production of LdhA was greatest when glucose was the carbon source, followed by xylose and trehalose; all of these sugars could be fermented to lactic acid. Transcripts fromldhBwere not detected whenR. oryzaewas grown on any of these sugars but were present whenR. oryzaewas grown on glycerol, ethanol, and lactate. I hypothesize thatldhBencodes a second NAD+-dependent LDH that is capable of convertingl-lactate to pyruvate and is produced by cultures grown on these nonfermentable substrates. BothldhAandldhBrestored fermentative growth toEscherichia coli(ldhA pfl) mutants so that they grew anaerobically and produced lactic acid.
Characterization of Metabolites during Biodegradation of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine (RDX) with Municipal Anaerobic Sludge
Authors: Hawari Jalal , Halasz Annamaria , Sheremata Tamara , Beaudet Sylvie , Groom Carl , Paquet Louise , Rhofir Chakib , Ampleman Guy , Thiboutot Sonia
Published: July 2002

The biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in liquid cultures with municipal anaerobic sludge showed that at least two degradation routes were involved in the disappearance of the cyclic nitramine. In one route, RDX was reduced to give the familiar nitroso derivatives hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) and hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX). In the second route, two novel metabolites, methylenedinitramine [(O
2
NNH)
2
CH
2
] and bis(hydroxymethyl)nitramine [(HOCH
2
)
2
NNO
2
], formed and were presumed to be ring cleavage products produced by enzymatic hydrolysis of the inner C—N bonds of RDX. None of the above metabolites accumulated in the system, and they disappeared to produce nitrous oxide (N
2
O) as a nitrogen-containing end product and formaldehyde (HCHO), methanol (MeOH), and formic acid (HCOOH) that in turn disappeared to produce CH
4
and CO
2
as carbon-containing end products.
Fermentation of Fructooligosaccharides by Lactic Acid Bacteria and Bifidobacteria
Authors: Kaplan Handan , Hutkins Robert W.
Published: July 2002

Lactic acid bacteria and bifidobacteria were screened of their ability to ferment fructooligosaccharides (FOS) on MRS agar. Of 28 strains of lactic acid bacteria and bifidobacteria examined, 12 of 16
Lactobacillus
strains and 7 of 8
Bifidobacterium
strains fermented FOS. Only strains that gave a positive reaction by the agar method reached high cell densities in broth containing FOS.
Isolation and Characterization of Diverse Halobenzoate-Degrading Denitrifying Bacteria from Soils and Sediments
Authors: Song Bongkeun , Palleroni Norberto J. , Häggblom Max M.
Published: July 2002

Denitrifying bacteria capable of degrading halobenzoates were isolated from various geographical and ecological sites. The strains were isolated after initial enrichment on one of the monofluoro-, monochloro-, or monobromo-benzoate isomers with nitrate as an electron acceptor, yielding a total of 33 strains isolated from the different halobenzoate-utilizing enrichment cultures. Each isolate could grow on the selected halobenzoate with nitrate as the terminal electron acceptor. The isolates obtained on 2-fluorobenzoate could use 2-fluorobenzoate under both aerobic and denitrifying conditions, but did not degrade other halobenzoates. In contrast, the 4-fluorobenzoate isolates degraded 4-fluorobenzoate under denitrifying conditions only, but utilized 2-fluorobenzoate under both aerobic and denitrifying conditions. The strains isolated on either 3-chlorobenzoate or 3-bromobenzoate could use 3-chlorobenzoate, 3-bromobenzoate, and 2- and 4-fluorobenzoates under denitrifying conditions. The isolates were identified and classified on the basis of 16S rRNA gene sequence analysis and their cellular fatty acid profiles. They were placed in nine genera belonging to either the α-, β-, or γ-branch of theProteobacteria, namely,Acidovorax,Azoarcus,Bradyrhizobium,Ochrobactrum,Paracoccus,Pseudomonas,Mesorhizobium,Ensifer, andThauera. These results indicate that the ability to utilize different halobenzoates under denitrifying conditions is ubiquitously distributed in theProteobacteriaand that these bacteria are widely distributed in soils and sediments.
Development and Characterization of Diamondback Moth Resistance to Transgenic Broccoli Expressing High Levels of Cry1C
Authors: Zhao Jian-Zhou , Collins Hilda L. , Tang Juliet D. , Cao Jun , Earle Elizabeth D. , Roush Richard T. , Herrero Salvador , Escriche Baltasar , Ferré Juan , Shelton Anthony M.
Published: July 2002

A field-collected colony of the diamondback moth,
Plutella xylostella
, had 31-fold resistance to Cry1C protoxin of
Bacillus thuringiensis
. After 24 generations of selection with Cry1C protoxin and transgenic broccoli expressing a Cry1C protein, the resistance that developed was high enough that neonates of the resistant strain could complete their entire life cycle on transgenic broccoli expressing high levels of Cry1C. After 26 generations of selection, the resistance ratios of this strain to Cry1C protoxin were 12,400- and 63,100-fold, respectively, for the neonates and second instars by a leaf dip assay. The resistance remained stable until generation 38 (G38) under continuous selection but decreased to 235-fold at G38 when selection ceased at G28. The Cry1C resistance in this strain was seen to be inherited as an autosomal and incompletely recessive factor or factors when evaluated using a leaf dip assay and recessive when evaluated using Cry1C transgenic broccoli. Saturable binding of
125
I-Cry1C was found with brush border membrane vesicles (BBMV) from both susceptible and Cry1C-resistant strains. Significant differences in Cry1C binding to BBMV from the two strains were detected. BBMV from the resistant strain had about sevenfold-lower affinity for Cry1C and threefold-higher binding site concentration than BBMV from the susceptible strain. The overall Cry1C binding affinity was just 2.5-fold higher for BBMV from the susceptible strain than it was for BBMV from the resistant strain. These results suggest that reduced binding is not the major mechanism of resistance to Cry1C.
Biotransformation of the Antimelanoma Agent Betulinic Acid by
Bacillus megaterium
ATCC 13368
Authors: Chatterjee Parnali , Kouzi Samir A. , Pezzuto John M. , Hamann Mark T.
Published: July 2002

Microbial transformation of the antimelanoma agent betulinic acid was studied. The main objective of this study was to utilize microorganisms as in vitro models to predict and prepare potential mammalian metabolites of this compound. Preparative-scale biotransformation with resting-cell suspensions of
Bacillus megaterium
ATCC 13368 resulted in the production of four metabolites, which were identified as 3-oxo-lup-20(29)-en-28-oic acid, 3-oxo-11α-hydroxy-lup-20(29)-en-28-oic acid, 1β-hydroxy-3-oxo-lup-20(29)-en-28-oic acid, and 3β,7β,15α-trihydroxy-lup-20(29)-en-28-oic acid based on nuclear magnetic resonance and high-resolution mass spectral analyses. In addition, the antimelanoma activities of these metabolites were evaluated with two human melanoma cell lines, Mel-1 (lymph node) and Mel-2 (pleural fluid).
Phylogenetic Analysis of Bacterial Communities in Mesophilic and Thermophilic Bioreactors Treating Pharmaceutical Wastewater
Authors: LaPara Timothy M. , Nakatsu Cindy H. , Pantea Lisa , Alleman James E.
Published: July 2002

The phylogenetic diversity of the bacterial communities supported by a seven-stage, full-scale biological wastewater treatment plant was studied. These reactors were operated at both mesophilic (28 to 32°C) and thermophilic (50 to 58°C) temperatures. Community fingerprint analysis by denaturing gradient gel electrophoresis (DGGE) of the PCR-amplified V3 region of the 16S rRNA gene from the domain
Bacteria
revealed that these seven reactors supported three distinct microbial communities. A band-counting analysis of the PCR-DGGE results suggested that elevated reactor temperatures corresponded with reduced species richness. Cloning of nearly complete 16S rRNA genes also suggested a reduced species richness in the thermophilic reactors by comparing the number of clones with different nucleotide inserts versus the total number of clones screened. While these results imply that elevated temperature can reduce species richness, other factors also could have impacted the number of populations that were detected. Nearly complete 16S rDNA sequence analysis showed that the thermophilic reactors were dominated by members from the β subdivision of the division
Proteobacteria
(β-proteobacteria) in addition to anaerobic phylotypes from the low-G+C gram-positive and
Synergistes
divisions. The mesophilic reactors, however, included at least six bacterial divisions, including
Cytophaga-Flavobacterium-Bacteroides
,
Synergistes
,
Planctomycetes
, low-G+C gram-positives,
Holophaga-Acidobacterium
, and
Proteobacteria
(α-proteobacteria, β-proteobacteria, γ-proteobacteria and δ-proteobacteria subdivisions). The two PCR-based techniques detected the presence of similar bacterial populations but failed to coincide on the relative distribution of these phylotypes. This suggested that at least one of these methods is insufficiently quantitative to determine total community biodiversity—a function of both the total number of species present (richness) and their relative distribution (evenness).
Effect of Oxygen on Formation and Structure of
Azotobacter vinelandii
Alginate and Its Role in Protecting Nitrogenase
Authors: Sabra W. , Zeng A.-P. , Lünsdorf H. , Deckwer W.-D.
Published: July 2002

The activity of nitrogenase in the nitrogen-fixing bacterium
Azotobacter vinelandii
grown diazotrophically under aerobic conditions is generally considered to be protected against O
2
by a high respiration rate. In this work, we have shown that a high rate of respiration is not the prevailing mechanism for nitrogenase protection in
A. vinelandii
grown in phosphate-limited nitrogen-free chemostat culture. Instead, the formation of alginate appeared to play a decisive role in protecting the nitrogenase that is required for cell growth in this culture. Depending on the O
2
tension and cell growth rate, the formation rate and composition of alginate released into the culture broth varied significantly. Furthermore, transmission electron microscopic analysis of cell morphology and the cell surface revealed the existence of an alginate capsule on the surface of
A. vinelandii
. The composition, thickness, and compactness of this alginate capsule also varied significantly. In general, increasing O
2
tension led to the formation of alginate with a higher molecular weight and a greater
l
-guluronic acid content. The alginate capsule was accordingly thicker and more compact. In addition, the formation of the alginate capsule was found to be strongly affected by the shear rate in a bioreactor. Based on these experimental results, it is suggested that the production of alginate, especially the formation of an alginate capsule on the cell surface, forms an effective barrier for O
2
transfer into the cell. It is obviously the quality, not the quantity, of alginate that is decisive for the protection of nitrogenase.
Resuscitation by Ferrioxamine E of Stressed
Salmonella enterica
Serovar Typhimurium from Soil and Water Microcosms
Authors: Reissbrodt R. , Heier H. , Tschäpe H. , Kingsley R. A. , Williams P. H.
Published: July 2002

Storage of
Salmonella enterica
serovar Typhimurium strains in soil and water microcosms resulted in loss of culturability on standard plating media. Prior incubation in buffered peptone water supplemented with ferrioxamine E markedly extended the time that bacteria were recoverable by plating, except in the case of mutants deficient in ferrioxamine E uptake.
Inhibition of
Giardia intestinalis
by Extracellular Factors from Lactobacilli: an In Vitro Study
Authors: Pérez Pablo F. , Minnaard Jessica , Rouvet Martine , Knabenhans Christian , Brassart Dominique , De Antoni Graciela L. , Schiffrin Eduardo J.
Published: July 2002

The aim of the present work was to evaluate the effect of spent culture supernatants of different strains of lactobacilli on giardia trophozoites. The growth of
Giardia intestinalis
strain WB, as well as the attachment to the human intestinal epithelial cell line Caco-2, was evaluated by using proliferation and adhesion assays with radiolabeled parasites. In addition, scanning electron microscopy and flow cytometric analysis were performed. The effect of spent culture supernatants from lactobacilli was strain dependent.
Lactobacillus johnsonii
La1 significantly inhibited the proliferation of
G. intestinalis
trophozoites. Although the effect was strongly pH dependent, it was not simply due to lactic acid. According to flow cytometric analysis, trophozoites were arrested in G
1
phase but neither significant necrosis nor apoptosis could be detected. Bacterial cells or their spent culture supernatants were unable to modify trophozoite attachment to Caco-2 cells. However, trophozoites treated with spent culture supernatants had little, if any, proliferative capacity. These results suggest that La1 produces some substance(s) able to inhibit proliferation of
Giardia
trophozoites. Partial characterization of the factors involved in the antigiardiasic action showed that they have a low molecular mass and are inactivated by heating. On this basis, it seems worthwhile to explore how colonization of the proximal small bowel with these lactic acid bacteria could interfere with giardiasis in vivo.
High Genetic Variability for Resistance to
Bacillus thuringiensis
Toxins in a Single Population of Diamondback Moth
Authors: González-Cabrera Joel , Herrero Salvador , Ferré Juan
Published: July 2002

The long-term benefit of insecticidal products based on Cry toxins, either in sprays or as transgenic crops, is threatened by the development of resistance by target pests. The models used to predict evolution of resistance to Cry toxins most often are monogenic models in which two alleles are used. Moreover, the high-dose/refuge strategy recommended for implementation with transgenic crops relies on the assumption that the resistance allele is recessive. Using selection experiments, we demonstrated the occurrence in a laboratory colony of diamondback moth of two different genes (either allelic or nonallelic) that confer resistance to Cry1Ab. At the concentration tested, resistance was dominant in one selection line and partially recessive in the other. Resistant insects from the two selection lines also differed in their cross-resistance patterns. The diamondback moth colony was derived from a field population from the Philippines, which originally showed a different resistance phenotype. This is the first time that an insect population has been directly shown to carry more than one gene conferring resistance to the same Cry toxin.
Examination of Peak Power Dependence in the UV Inactivation of Bacterial Spores
Authors: Rice Jane K. , Ewell Michael
Published: July 2002

We examine whether the rate of delivery of photons from a UV radiation source has an effect on the inactivation of spores. We directly compare the output of a high-peak-power UV laser source at 248 nm to a low-power continuous lamp source (254 nm) in the inactivation of
Bacillus
subtilis
spores. The two UV sources differ by a factor of 10
8
in peak power. Contrary to previous reports, no clear differences in spore survival were observed.
Dissection of Central Carbon Metabolism of Hemoglobin-Expressing
Escherichia coli
by
13
C Nuclear Magnetic Resonance Flux Distribution Analysis in Microaerobic Bioprocesses
Authors: Frey Alexander D. , Fiaux Jocelyne , Szyperski Thomas , Wüthrich Kurt , Bailey James E. , Kallio Pauli T.
Published: July 2002

Escherichia coli
MG1655 cells expressing
Vitreoscilla
hemoglobin (VHb),
Alcaligenes eutrophus
flavohemoprotein (FHP), the N-terminal hemoglobin domain of FHP (FHPg), and a fusion protein which comprises VHb and the
A. eutrophus
C-terminal reductase domain (VHb-Red) were grown in a microaerobic bioreactor to study the effects of low oxygen concentrations on the central carbon metabolism, using fractional
13
C-labeling of the proteinogenic amino acids and two-dimensional [
13
C,
1
H]-correlation nuclear magnetic resonance (NMR) spectroscopy. The NMR data revealed differences in the intracellular carbon fluxes between
E. coli
cells expressing either VHb or VHb-Red and cells expressing
A. eutrophus
FHP or the truncated heme domain (FHPg).
E. coli
MG1655 cells expressing either VHb or VHb-Red were found to function with a branched tricarboxylic acid (TCA) cycle. Furthermore, cellular demands for ATP and reduction equivalents in VHb- and VHb-Red-expressing cells were met by an increased flux through glycolysis. In contrast, in
E. coli
cells expressing
A. eutrophus
hemeproteins, the TCA cycle is running cyclically, indicating a shift towards a more aerobic regulation. Consistently,
E. coli
cells displaying FHP and FHPg activity showed lower production of the typical anaerobic by-products formate, acetate, and
d
-lactate. The implications of these observations for biotechnological applications are discussed.
Genetic Diversity among 3-Chloroaniline- and Aniline-Degrading Strains of the
Comamonadaceae
Authors: Boon Nico , Goris Johan , De Vos Paul , Verstraete Willy , Top Eva M.
Published: July 2002

We examined the diversity of the plasmids and of the gene
tdnQ
, involved in the oxidative deamination of aniline, in five bacterial strains that are able to metabolize both aniline and 3-chloroaniline (3-CA). Three strains have been described and identified previously, i.e.,
Comamonas testosteroni
I2 and
Delftia acidovorans
CA28 and BN3.1. Strains LME1 and B8c were isolated in this study from linuron-treated soil and from a wastewater treatment plant, respectively, and were both identified as
D. acidovorans
. Both
Delftia
and
Comamonas
belong to the family
Comamonadaceae
. All five strains possess a large plasmid of ca. 100 kb, but the plasmids from only four strains could be transferred to a recipient strain by selection on aniline or 3-CA as a sole source of carbon and/or nitrogen. Plasmid transfer experiments and Southern hybridization revealed that the plasmid of strain I2 was responsible for total aniline but not 3-CA degradation, while the plasmids of strains LME1 and B8c were responsible only for the oxidative deamination of aniline. Several transconjugant clones that had received the plasmid from strain CA28 showed different degradative capacities: all transconjugants could use aniline as a nitrogen source, while only some of the transconjugants could deaminate 3-CA. For all four plasmids, the IS
1071
insertion sequence of Tn
5271
was found to be located on a 1.4-kb restriction fragment, which also hybridized with the
tdnQ
probe. This result suggests the involvement of this insertion sequence element in the dissemination of aniline degradation genes in the environment. By use of specific primers for the
tdnQ
gene from
Pseudomonas putida
UCC22, the diversity of the PCR-amplified fragments in the five strains was examined by denaturing gradient gel electrophoresis (DGGE). With DGGE, three different clusters of the
tdnQ
fragment could be distinguished. Sequencing data showed that the
tdnQ
sequences of I2, LME1, B8c, and CA28 were very closely related, while the
tdnQ
sequences of BN3.1 and
P. putida
UCC22 were only about 83% identical to the other sequences. Northern hybridization revealed that the
tdnQ
gene is transcribed only in the presence of aniline and not when only 3-CA is present.
Evidence for a Genetically Stable Strain of
Campylobacter jejuni
Authors: Manning G. , Duim B. , Wassenaar T. , Wagenaar J. A. , Ridley A. , Newell D. G.
Published: July 2002

The genetic stability of selected epidemiologically linked strains of
Campylobacter jejuni
during outbreak situations was investigated by using subtyping techniques. Strains isolated from geographically related chicken flock outbreaks in 1998 and from a human outbreak in 1981 were investigated. There was little similarity in the strains obtained from the different chicken flock outbreaks; however, the strains from each of three chicken outbreaks, including strains isolated from various environments, were identical as determined by
fla
typing, amplified fragment length polymorphism (AFLP) analysis, and pulsed-field gel electrophoresis, which confirmed the genetic stability of these strains during the short time courses of chicken flock outbreaks. The human outbreak samples were compared with strain 81116, which originated from the same outbreak but has since undergone innumerable laboratory passages. Two main AFLP profiles were recognized from this outbreak, which confirmed the serotyping results obtained at the time of the outbreak. The major type isolated from this outbreak (serotype P6:L6) was exemplified by strain 81116. Despite the long existence of strain 81116 as a laboratory strain, the AFLP profile of this strain was identical to the profiles of all the other historical P6:L6 strains from the outbreak, indicating that the genotype has remained stable for almost 20 years. Interestingly, the AFLP profiles of the P6:L6 group of strains from the human outbreak and the strains from one of the recent chicken outbreaks were also identical. This similarity suggests that some clones of
C. jejuni
remain genetically stable in completely different environments over long periods of time and considerable geographical distances.
Cytotoxicity Associated with Trichloroethylene Oxidation in
Burkholderia cepacia
G4
Authors: Yeager Chris M. , Bottomley Peter J. , Arp Daniel J.
Published: July 2002

The effects of trichloroethylene (TCE) oxidation on toluene 2-monooxygenase activity, general respiratory activity, and cell culturability were examined in the toluene-oxidizing bacterium
Burkholderia cepacia
G4. Nonspecific damage outpaced inactivation of toluene 2-monooxygenase in
B. cepacia
G4 cells. Cells that had degraded approximately 0.5 μmol of TCE (mg of cells
−1
) lost 95% of their acetate-dependent O
2
uptake activity (a measure of general respiratory activity), yet toluene-dependent O
2
uptake activity decreased only 35%. Cell culturability also decreased upon TCE oxidation; however, the extent of loss varied greatly (up to 3 orders of magnitude) with the method of assessment. Addition of catalase or sodium pyruvate to the surfaces of agar plates increased enumeration of TCE-injured cells by as much as 100-fold, indicating that the TCE-injured cells were ultrasensitive to oxidative stress. Cell suspensions that had oxidized TCE recovered the ability to grow in liquid minimal medium containing lactate or phenol, but recovery was delayed substantially when TCE degradation approached 0.5 μmol (mg of cells
−1
) or 66% of the cells' transformation capacity for TCE at the cell density utilized. Furthermore, among
B. cepacia
G4 cells isolated on Luria-Bertani agar plates from cultures that had degraded approximately 0.5 μmol of TCE (mg of cells
−1
), up to 90% were Tol
−
variants, no longer capable of TCE degradation. These results indicate that a toxicity threshold for TCE oxidation exists in
B. cepacia
G4 and that once a cell suspension has exceeded this toxicity threshold, the likelihood of reestablishing an active, TCE-degrading biomass from the cells will decrease significantly.
Kinetics of Methyl
t
-Butyl Ether Cometabolism at Low Concentrations by Pure Cultures of Butane-Degrading Bacteria
Authors: Liu Catherine Y. , Speitel Gerald E. , Georgiou George
Published: July 2002

Butane-oxidizing
Arthrobacter
(ATCC 27778) bacteria were shown to degrade low concentrations of methyl
t
-butyl ether (MTBE; range, 100 to 800 μg/liter) with an apparent half-saturation concentration (
K

s

) of 2.14 mg/liter and a maximum substrate utilization rate (k
c
) of 0.43 mg/mg of total suspended solids per day.
Arthrobacter
bacteria demonstrated MTBE degradation activity when grown on butane but not when grown on glucose, butanol, or tryptose phosphate broth. The presence of butane,
tert
-butyl alcohol, or acetylene had a negative impact on the MTBE degradation rate. Neither
Methylosinus trichosporium
OB3b nor
Streptomyces griseus
was able to cometabolize MTBE.