bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dibenzyl Sulfide Metabolism by White Rot Fungi
Authors: Van Hamme Jonathan D. , Wong Eddie T. , Dettman Heather , Gray Murray R. , Pickard Michael A. 
Published: February 2003

ABSTRACT

Microbial metabolism of organosulfur compounds is of interest in the petroleum industry for in-field viscosity reduction and desulfurization. Here, dibenzyl sulfide (DBS) metabolism in white rot fungi was studied.
Trametes trogii
UAMH 8156,
Trametes hirsuta
UAMH 8165,
Phanerochaete chrysosporium
ATCC 24725,
Trametes versicolor
IFO 30340 (formerly
Coriolus
sp.), and
Tyromyces palustris
IFO 30339 all oxidized DBS to dibenzyl sulfoxide prior to oxidation to dibenzyl sulfone. The cytochrome P-450 inhibitor 1-aminobenzotriazole eliminated dibenzyl sulfoxide oxidation. Laccase activity (0.15 U/ml) was detected in the
Trametes
cultures, and concentrated culture supernatant and pure laccase catalyzed DBS oxidation to dibenzyl sulfoxide more efficiently in the presence of 2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) than in its absence. These data suggest that the first oxidation step is catalyzed by extracellular enzymes but that subsequent metabolism is cytochrome P-450 mediated.
Chlorine Inactivation of Spores of
Encephalitozoon
spp
Authors: Johnson C. H. , Marshall M. M. , DeMaria L. A. , Moffet J. M. , Korich D. G. 
Published: February 2003

ABSTRACT

This report is an extension of a preliminary investigation on the use of chlorine to inactivate spores of
Encephalitozoon
intestinalis
and to investigate the effect of chlorine on two other species,
E
cuniculi
and
E
.
hellem
, associated with human infection. The 50% tissue culture infective doses of these three species were also determined. On the basis of the results obtained, it appears that chlorination of water is an effective means of controlling spores of these organisms in the aquatic environment.
UV Resistance of
Bacillus anthracis
Spores Revisited: Validation of
Bacillus subtilis
Spores as UV Surrogates for Spores of
B. anthracis
Sterne
Authors: Nicholson Wayne L. , Galeano Belinda 
Published: February 2003

ABSTRACT

Recent bioterrorism concerns have prompted renewed efforts towards understanding the biology of bacterial spore resistance to radiation with a special emphasis on the spores of
Bacillus anthracis.
A review of the literature revealed that
B. anthracis
Sterne spores may be three to four times more resistant to 254-nm-wavelength UV than are spores of commonly used indicator strains of
Bacillus subtilis
. To test this notion,
B. anthracis
Sterne spores were purified and their UV inactivation kinetics were determined in parallel with those of the spores of two indicator strains of
B. subtilis
, strains WN624 and ATCC 6633. When prepared and assayed under identical conditions, the spores of all three strains exhibited essentially identical UV inactivation kinetics. The data indicate that standard UV treatments that are effective against
B. subtilis
spores are likely also sufficient to inactivate
B. anthracis
spores and that the spores of standard
B. subtilis
strains could reliably be used as a biodosimetry model for the UV inactivation of
B. anthracis
spores.
Recombinant Strain of
Bacillus thuringiensis
Producing Cyt1A, Cry11B, and the
Bacillus sphaericus
Binary Toxin
Authors: Park Hyun-Woo , Bideshi Dennis K. , Federici Brian A. 
Published: February 2003

ABSTRACT

A novel recombinant
Bacillus thuringiensis
subsp.
israelensis
strain that produces the
B. sphaericus
binary toxin, Cyt1Aa, and Cry11Ba is described. The toxicity of this strain (50% lethal concentration [LC
50
] = 1.7 ng/ml) against fourth-instar
Culex quinquefasciatus
was higher than that of
B. thuringiensis
subsp.
israelensis
IPS-82 (LC
50
= 7.9 ng/ml) or
B. sphaericus
2362 (LC
50
= 12.6 ng/ml).
Molecular Analysis of a
Saccharomyces cerevisiae
Mutant with Improved Ability To Utilize Xylose Shows Enhanced Expression of Proteins Involved in Transport, Initial Xylose Metabolism, and the Pentose Phosphate Pathway
Authors: Wahlbom C. Fredrik , Cordero Otero Ricardo R. , van Zyl Willem H. , Hahn-Hägerdal Bärbel , Jönsson Leif J. 
Published: February 2003

ABSTRACT

Differences between the recombinant xylose-utilizing
Saccharomyces cerevisiae
strain TMB 3399 and the mutant strain TMB 3400, derived from TMB 3399 and displaying improved ability to utilize xylose, were investigated by using genome-wide expression analysis, physiological characterization, and biochemical assays. Samples for analysis were withdrawn from chemostat cultures. The characteristics of
S. cerevisiae
TMB 3399 and TMB 3400 grown on glucose and on a mixture of glucose and xylose, as well as of
S. cerevisiae
TMB 3400 grown on only xylose, were investigated. The strains were cultivated under chemostat conditions at a dilution rate of 0.1 h
−1
, with feeds consisting of a defined mineral medium supplemented with 10 g of glucose liter
−1
, 10 g of glucose plus 10 g of xylose liter
−1
or, for
S. cerevisiae
TMB 3400, 20 g of xylose liter
−1
.
S. cerevisiae
TMB 3400 consumed 31% more xylose of a feed containing both glucose and xylose than
S. cerevisiae
TMB 3399. The biomass yields for
S. cerevisiae
TMB 3400 were 0.46 g of biomass g of consumed carbohydrate
−1
on glucose and 0.43 g of biomass g of consumed carbohydrate
−1
on xylose. A

K
s

value of 33 mM for xylose was obtained for
S. cerevisiae
TMB 3400. In general, the percentage error was <20% between duplicate microarray experiments originating from independent fermentation experiments. Microarray analysis showed higher expression in
S. cerevisiae
TMB 3400 than in
S. cerevisiae
TMB 3399 for (i)
HXT5
, encoding a hexose transporter; (ii)
XKS1
, encoding xylulokinase, an enzyme involved in one of the initial steps of xylose utilization; and (iii)
SOL3
,
GND1
,
TAL1
, and
TKL1
, encoding enzymes in the pentose phosphate pathway. In addition, the transcriptional regulators encoded by YCR020C, YBR083W, and YPR199C were expressed differently in the two strains. Xylose utilization was, however, not affected in strains in which YCR020C was overexpressed or deleted. The higher expression of
XKS1
in
S. cerevisiae
TMB 3400 than in TMB 3399 correlated with higher specific xylulokinase activity in the cell extracts. The specific activity of xylose reductase and xylitol dehydrogenase was also higher for
S. cerevisiae
TMB 3400 than for TMB 3399, both on glucose and on the mixture of glucose and xylose.
Anaerobic Degradation of Ethylbenzene by a New Type of Marine Sulfate-Reducing Bacterium
Authors: Kniemeyer Olaf , Fischer Thomas , Wilkes Heinz , Glöckner Frank Oliver , Widdel Friedrich 
Published: February 2003

ABSTRACTAnaerobic degradation of the aromatic hydrocarbon ethylbenzene was studied with sulfate as the electron acceptor. Enrichment cultures prepared with marine sediment samples from different locations showed ethylbenzene-dependent reduction of sulfate to sulfide and always contained a characteristic cell type that formed gas vesicles towards the end of growth. A pure culture of this cell type, strain EbS7, was isolated from sediment from Guaymas Basin (Gulf of California). Complete mineralization of ethylbenzene coupled to sulfate reduction was demonstrated in growth experiments with strain EbS7. Sequence analysis of the 16S rRNA gene revealed a close relationship between strain EbS7 and the previously described marine sulfate-reducing strains NaphS2 and mXyS1 (similarity values, 97.6 and 96.2%, respectively), which grow anaerobically with naphthalene andm-xylene, respectively. However, strain EbS7 did not oxidize naphthalene,m-xylene, or toluene. Other compounds utilized by strain EbS7 were phenylacetate, 3-phenylpropionate, formate,n-hexanoate, lactate, and pyruvate. 1-Phenylethanol and acetophenone, the characteristic intermediates in anaerobic ethylbenzene degradation by denitrifying bacteria, neither served as growth substrates nor were detectable as metabolites by gas chromatography-mass spectrometry in ethylbenzene-grown cultures of strain EbS7. Rather, (1-phenylethyl)succinate and 4-phenylpentanoate were detected as specific metabolites in such cultures. Formation of these intermediates can be explained by a reaction sequence involving addition of the benzyl carbon atom of ethylbenzene to fumarate, carbon skeleton rearrangement of the succinate moiety (as a thioester), and loss of one carboxyl group. Such reactions are analogous to those suggested for anaerobicn-alkane degradation and thus differ from the initial reactions in anaerobic ethylbenzene degradation by denitrifying bacteria which employ dehydrogenations.
The Abundance of Microcystin-Producing Genotypes Correlates Positively with Colony Size inMicrocystissp. and Determines Its Microcystin Net Production in Lake Wannsee
Authors: Kurmayer Rainer , Christiansen Guntram , Chorus Ingrid 
Published: February 2003

ABSTRACTThe working hypotheses tested on a natural population ofMicrocystissp. in Lake Wannsee (Berlin, Germany) were that (i) the varying abundance of microcystin-producing genotypes versus non-microcystin-producing genotypes is a key factor for microcystin net production and (ii) the occurrence of a gene for microcystin net production is related to colony morphology, particularly colony size. To test these hypotheses, samples were fractionated by colony size with a sieving procedure during the summer of 2000. Each colony size class was analyzed for cell numbers, the proportion of microcystin-producing genotypes, and microcystin concentrations. The smallest size class ofMicrocystiscolonies (<50 μm) showed the lowest proportion of microcystin-producing genotypes, the highest proportion of non-microcystin-producing cells, and the lowest microcystin cell quotas (sum of microcystins RR, YR, LR, and WR). In contrast, the larger size classes ofMicrocystiscolonies (>100 μm) showed the highest proportion of microcystin-producing genotypes, the lowest proportion of non-microcystin-producing cells, and the highest microcystin cell quotas. The microcystin net production rate was nearly one to one positively related to the population growth rate for the larger colony size classes (>100 μm); however, no relationship could be found for the smaller size classes. It was concluded that the variations found in microcystin net production between colony size classes are chiefly due to differences in genotype composition and that the microcystin net production in the lake is mainly influenced by the abundance of the larger (>100-μm) microcystin-producing colonies.
A Sensitive and Inexpensive Yeast Bioassay for the Mycotoxin Zearalenone and Other Compounds with Estrogenic Activity
Authors: Mitterbauer Rudolf , Weindorfer Hanna , Safaie Naser , Krska Rudolf , Lemmens Marc , Ruckenbauer Peter , Kuchler Karl , Adam Gerhard 
Published: February 2003

ABSTRACT

Zearalenone (ZON) is a nonsteroidal estrogenic mycotoxin produced by plant-pathogenic species of
Fusarium
. As a consequence of infection with
Fusarium culmorum
and
Fusarium graminearum
, ZON can be found in cereals and derived food products. Since ZON is suspected to be a cause of human disease, including premature puberty syndrome, as well as hyperestrogenism in farm animals, several countries have established monitoring programs and guidelines for ZON levels in grain intended for human consumption and animal feed. We developed a low-cost method for monitoring ZON contamination in grain based on a sensitive yeast bioassay. The indicator
Saccharomyces cerevisiae
strain YZRM7 is unable to grow unless an engineered pyrimidine biosynthetic gene is activated by the expressed human estrogen receptor in the presence of exogenous estrogenic substances. Deletion of the genes encoding ATP-binding cassette (ABC) transporters Pdr5p and Snq2p increases net ZON uptake synergistically. Less than 1 μg of ZON per liter of medium is sufficient to allow growth of the indicator strain. To prevent interference with pyrimidines potentially present in biological samples, we also disrupted the genes
FUR1
and
URK1
, blocking the pyrimidine salvage pathway. The bioassay strain YZRM7 allows qualitative detection and quantification of total estrogenic activity in cereal extracts without requiring further cleanup steps. Its high sensitivity makes this assay suitable for low-cost monitoring of contamination of maize and small grain cereals with estrogenic
Fusarium
mycotxins.
Integrative Transformation System for the Metabolic Engineering of the Sphingoid Base-Producing Yeast
Pichia ciferrii
Authors: Bae Jung-Hoon , Sohn Jung-Hoon , Park Chang-Seo , Rhee Joon-Shick , Choi Eui-Sung 
Published: February 2003

ABSTRACT

We have developed an integrative transformation system for metabolic engineering of the tetraacetyl phytosphingosine (TAPS)-secreting yeast
Pichia ciferrii
. The system uses (i) a mutagenized ribosomal protein L41 gene of
P. ciferrii
as a dominant selection marker that confer resistance to the antibiotic cycloheximide and (ii) a ribosomal DNA (rDNA) fragment of
P. ciferrii
as a target for multicopy gene integration into the chromosome. A locus within the nontranscribed region located between 5S and 26S rDNAs was selected as the integration site. A maximum frequency of integrative transformation of approximately 1,350 transformants/μg of DNA was observed. To improve the de novo synthesis of sphingolipid, the
LCB2
gene, encoding a subunit of serine palmitoyltransferase, which catalyzes the first committed step of sphingolipid synthesis, was cloned from
P. ciferrii
and overexpressed under the control of the
P. ciferrii
glyceraldehyde-3-phosphate dehydrogenase promoter. After transformation of an
LCB2
gene expression cassette, several transformants that contained approximately five to seven copies of transforming DNA in the chromosome and exhibited about 50-fold increase in
LCB2
mRNA relative to the wild type were identified. These transformants were observed to produce approximately two times more TAPS than the wild type.
Bacterial Population Changes in a Membrane Bioreactor for Graywater Treatment Monitored by Denaturing Gradient Gel Electrophoretic Analysis of 16S rRNA Gene Fragments
Authors: Stamper David M. , Walch Marianne , Jacobs Rachel N. 
Published: February 2003

ABSTRACT

The bacterial population of a graywater treatment system was monitored over the course of 100 days, along with several wastewater biochemical parameters. The graywater treatment system employed an 1,800-liter membrane bioreactor (MBR) to process the waste, with essentially 100% recycling of the biomass. Graywater feed consisting of 10% galley water and 90% laundry water, selected to approximate the graywater composition on board U.S. Navy ships, was collected offsite. Five-day biological oxygen demand (BOD
5
), oils and greases (O/G), nitrogen, and phosphorus were monitored in the feed and were found to vary greatly day to day. Changes in the bacterial population were monitored by PCR amplification of region 332 to 518 (
Escherichia coli
numbering) of the 16S rRNA gene and denaturing gradient gel electrophoresis (DGGE) analysis of the resultant PCR products. DGGE analysis indicated a diverse and unstable bacterial population throughout the 100-day period, with spikes in feed strength causing significant changes in community structure. Long-term similarity between the communities was 0 to 25%, depending on the method of analysis. In spite of the unstable bacterial population, the MBR system was able to meet effluent quality parameters approximately 90% of the time.
Production of Cyclic Lipopeptides byPseudomonas fluorescensStrains in Bulk Soil and in the Sugar Beet Rhizosphere
Authors: Nielsen Tommy Harder , Sørensen Jan 
Published: February 2003

ABSTRACTThe production of cyclic lipopeptides (CLPs) with antifungal and biosurfactant properties byPseudomonas fluorescensstrains was investigated in bulk soil and in the sugar beet rhizosphere. Purified CLPs (viscosinamide, tensin, and amphisin) were first shown to remain highly stable and extractable (90%) when applied (ca. 5 μg g−1) to sterile soil, whereas all three compounds were degraded over 1 to 3 weeks in nonsterile soil. When a whole-cell inoculum ofP. fluorescensstrain DR54 containing a cell-bound pool of viscosinamide was added to the nonsterile soil, declining CLP concentrations were observed over a week. By comparison, addition of the strains 96.578 and DSS73 without cell-bound CLP pools did not result in detectable tensin or amphisin in the soil. In contrast, when sugar beet seeds were coated with the CLP-producing strains and subsequently germinated in nonsterile soil, strain DR54 maintained a high and constant viscosinamide level in the young rhizosphere for ∼2 days while strains 96.578 and DSS73 exhibited significant production (net accumulation) of tensin or amphisin, reaching a maximum level after 2 days. All three CLPs remained detectable for several days in the rhizosphere. Subsequent tests of five other CLP-producingP. fluorescensstrains also demonstrated significant production in the young rhizosphere. The results thus provide evidence that production of different CLPs is a common trait among manyP. fluorescensstrains in the soil environment, and further, that the production is taking place only in specific habitats like the rhizosphere of germinating sugar beet seeds rather than in the bulk soil.
Arthrobacter
Strain VAI-A Utilizes Acyl-Homoserine Lactone Inactivation Products and Stimulates Quorum Signal Biodegradation by
Variovorax paradoxus
Authors: Flagan Suvi , Ching Weng-Ki , Leadbetter Jared R. 
Published: February 2003

ABSTRACT

Many
Proteobacteria
produce acyl-homoserine lactones (acyl-HSLs) and employ them as dedicated cell-to-cell signals in a process known as quorum sensing. Previously,
Variovorax paradoxus
VAI-C was shown to utilize diverse acyl-HSLs as sole sources of energy and nitrogen. We describe here the properties of a second isolate,
Arthrobacter
strain VAI-A, obtained from the same enrichment culture that yielded
V. paradoxus
VAI-C. Although strain VAI-A grew rapidly and exponentially on a number of substrates, it grew only slowly and aberrantly (i.e., linearly) in media amended with oxohexanoyl-HSL as the sole energy source. Increasing the culture pH markedly improved the growth rate in media containing this substrate but did not abolish the aberrant kinetics. The observed growth was remarkably similar to the known kinetics of the pH-influenced half-life of acyl-HSLs, which decay chemically to yield the corresponding acyl-homoserines. Strain VAI-A grew rapidly and exponentially when provided with an acyl-homoserine as the sole energy or nitrogen source. The isolate was also able to utilize HSL as a sole source of nitrogen but not as energy for growth.
V. paradoxus
, known to release HSL as a product of quorum signal degradation, was examined for the ability to support the growth of
Arthrobacter
strain VAI-A in defined cocultures. It did. Moreover, the acyl-HSL-dependent growth rate and yield of the coculture were dramatically superior to those of the monocultures. This suggested that the original coenrichment of these two organisms from the same soil sample was not coincidental and that consortia may play a role in quorum signal turnover and mineralization. The fact that
Arthrobacter
strain VAI-A utilizes the two known nitrogenous degradation products of acyl-HSLs, acyl-homoserine and HSL, begins to explain why none of the three compounds are known to accumulate in the environment.
Terminal Restriction Fragment Length Polymorphism Data Analysis for Quantitative Comparison of Microbial Communities
Authors: Blackwood Christopher B. , Marsh Terry , Kim Sang-Hoon , Paul Eldor A. 
Published: February 2003

ABSTRACT
Terminal restriction fragment length polymorphism (T-RFLP) is a culture-independent method of obtaining a genetic fingerprint of the composition of a microbial community. Comparisons of the utility of different methods of (i) including peaks, (ii) computing the difference (or distance) between profiles, and (iii) performing statistical analysis were made by using replicated profiles of eubacterial communities. These samples included soil collected from three regions of the United States, soil fractions derived from three agronomic field treatments, soil samples taken from within one meter of each other in an alfalfa field, and replicate laboratory bioreactors. Cluster analysis by Ward's method and by the unweighted-pair group method using arithmetic averages (UPGMA) were compared. Ward's method was more effective at differentiating major groups within sets of profiles; UPGMA had a slightly reduced error rate in clustering of replicate profiles and was more sensitive to outliers. Most replicate profiles were clustered together when relative peak height or Hellinger-transformed peak height was used, in contrast to raw peak height. Redundancy analysis was more effective than cluster analysis at detecting differences between similar samples. Redundancy analysis using Hellinger distance was more sensitive than that using Euclidean distance between relative peak height profiles. Analysis of Jaccard distance between profiles, which considers only the presence or absence of a terminal restriction fragment, was the most sensitive in redundancy analysis, and was equally sensitive in cluster analysis, if all profiles had cumulative peak heights greater than 10,000 fluorescence units. It is concluded that T-RFLP is a sensitive method of differentiating between microbial communities when the optimal statistical method is used for the situation at hand. It is recommended that hypothesis testing be performed by redundancy analysis of Hellinger-transformed data and that exploratory data analysis be performed by cluster analysis using Ward's method to find natural groups or by UPGMA to identify potential outliers. Analyses can also be based on Jaccard distance if all profiles have cumulative peak heights greater than 10,000 fluorescence units.
In Situ Production of Exopolysaccharides during Sourdough Fermentation by Cereal and Intestinal Isolates of Lactic Acid Bacteria
Authors: Tieking Markus , Korakli Maher , Ehrmann Matthias A. , Gänzle Michael G. , Vogel Rudi F. 
Published: February 2003

ABSTRACT

EPS formed by lactobacilli in situ during sourdough fermentation may replace hydrocolloids currently used as texturizing, antistaling, or prebiotic additives in bread production. In this study, a screening of >100 strains of cereal-associated and intestinal lactic acid bacteria was performed for the production of exopolysaccharides (EPS) from sucrose. Fifteen strains produced fructan, and four strains produced glucan. It was remarkable that formation of glucan and fructan was most frequently found in intestinal isolates and strains of the species
Lactobacillus reuteri
,
Lactobacillus pontis
, and
Lactobacillus frumenti
from type II sourdoughs. By the use of PCR primers derived from conserved amino acid sequences of bacterial levansucrase genes, it was shown that 6 of the 15 fructan-producing lactobacilli and none of 20 glucan producers or EPS-negative strains carried a levansucrase gene. In sourdough fermentations, it was determined whether those strains producing EPS in MRS medium modified as described by Stolz et al. (37) and containing 100 g of sucrose liter
−1
as the sole source of carbon also produce the same EPS from sucrose during sourdough fermentation in the presence of 12% sucrose. For all six EPS-producing strains evaluated in sourdough fermentations, in situ production of EPS at levels ranging from 0.5 to 2 g/kg of flour was demonstrated. Production of EPS from sucrose is a metabolic activity that is widespread among sourdough lactic acid bacteria. Thus, the use of these organisms in bread production may allow the replacement of additives.