bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression and Regulation of the Arsenic Resistance Operon of
Acidiphilium multivorum
AIU 301 Plasmid pKW301 in
Escherichia coli
Authors: Suzuki Katsuhisa , Wakao Norio , Kimura Tetsuya , Sakka Kazuo , Ohmiya Kunio 
Published: December 2019

ABSTRACT

The arsenic resistance (
ars
) operon from plasmid pKW301 of
Acidiphilium multivorum
AIU 301 was cloned and sequenced. This DNA sequence contains five genes in the following order:
arsR
,
arsD
,
arsA
,
arsB
,
arsC
. The predicted amino acid sequences of all of the gene products are homologous to the amino acid sequences of the
ars
gene products of
Escherichia coli
plasmid R773 and IncN plasmid R46. The
ars
operon cloned from
A. multivorum
conferred resistance to arsenate and arsenite on
E. coli
. Expression of the
ars
genes with the bacteriophage T7 RNA polymerase-promoter system allowed
E. coli
to overexpress ArsD, ArsA, and ArsC but not ArsR or ArsB. The apparent molecular weights of ArsD, ArsA, and ArsC were 13,000, 64,000, and 16,000, respectively. A primer extension analysis showed that the
ars
mRNA started at a position 19 nucleotides upstream from the
arsR
ATG in
E. coli
. Although the
arsR
gene of
A. multivorum
AIU 301 encodes a polypeptide of 84 amino acids that is smaller and less homologous than any of the other ArsR proteins, inactivation of the
arsR
gene resulted in constitutive expression of the
ars
genes, suggesting that ArsR of pKW301 controls the expression of this operon.
Osmoregulatory Responses of Fungi Inhabiting Standing Litter of the Freshwater Emergent MacrophyteJuncus effusus
Authors: Kuehn Kevin A. , Churchill Perry F. , Suberkropp Keller 
Published: December 2019

ABSTRACTStanding litter of emergent macrophytes often forms a major portion of the detrital mass in wetland habitats. Microbial assemblages inhabiting this detritus must adapt physiologically to daily fluctuations in temperature and water availability. We examined the effects of various environmental conditions on the concentrations of osmoregulatory solutes (polyols and trehalose) and the respiratory activities of fungal assemblages inhabiting standing litter of the freshwater emergent macrophyteJuncus effusus. Under field conditions, the concentrations of osmolytes (polyols plus trehalose) in fungal decomposers were negatively correlated with plant litter water potentials (r= −0.75,P< 0.001) and rates of microbial respiration (r= −0.66,P< 0.001). The highest concentration of osmolytes (polyols plus trehalose) occurred in standing litter exposed to desiccating conditions (range from wet to dry, 0.06 to 0.68 μmol · mg of fungal biomass−1). Similar fluctuations in polyol and trehalose concentrations were observed in standing litter wetted and dried under laboratory conditions and for four predominant fungal decomposers ofJ. effususgrown individually on sterilizedJuncusleaves. These studies suggest that fungal inhabitants associated with standing litter of emergent macrophytes can adjust their intracellular solute concentrations in response to daily fluctuations in water availability.
Identification of Bacterial Isolates Obtained from Intestinal Contents Associated with 12,000-Year-Old Mastodon Remains
Authors: Rhodes A. N. , Urbance J. W. , Youga H. , Corlew-Newman H. , Reddy C. A. , Klug M. J. , Tiedje J. M. , Fisher D. C. 
Published: December 2019

ABSTRACTMastodon (Mammut americanum) remains unearthed during excavation of ancient sediments usually consist only of skeletal material, due to postmortem decomposition of soft tissues by microorganisms. Two recent excavations of skeletal remains in anoxic sediments in Ohio and Michigan, however, have uncovered organic masses which appear to be remnants of the small and large intestines, respectively. Macrobotanical examinations of the composition of these masses revealed assemblages of plant material radiocarbon dated to approximately 11,500 years before the present and thought to be incompletely digested food remains from this extinct mammal. We attempted to cultivate and identify bacteria from the intestinal contents, bone-associated sediments, and sediments not in proximity to the remains using a variety of general and selective media. In all, 295 isolates were cultivated, and 38 individual taxa were identified by fatty acid-methyl ester (FAME) profiles and biochemical characteristics (API-20E). The taxonomic positions of selected enteric and obligately anaerobic bacteria were confirmed by 16S ribosomal DNA (rDNA) sequencing. Results indicate that the intestinal and bone-associated samples contained the greatest diversity of bacterial taxa and that members of the familyEnterobacteriaceaerepresented 41% of all isolates and were predominant in the intestinal masses and sediments in proximity to the skeleton but were uncommon in the background sediments.Enterobacter cloacaewas the most commonly identified isolate, and partial rDNA sequencing revealed thatRahnella aquatiliswas the correct identity of strains suggested by FAME profiles to beYersinia enterocolitica. NoBacteroidesspp. or expected intestinal anaerobes were recovered. The only obligate anaerobes recovered were clostridia, and these were not recovered from the small intestinal masses. Microbiological evidence from this study supports other, macrobotanical data indicating the intestinal origin of these masses. Whether these organisms are direct descendants of the original intestinal microbiota, however, cannot be established.
A Nested Reverse Transcriptase PCR Assay for Detection of Small Round-Structured Viruses in Environmentally Contaminated Molluscan Shellfish
Authors: Green J. , Henshilwood K. , Gallimore C. I. , Brown D. W. G. , Lees D. N. 
Published: December 2019

ABSTRACT
We describe the evaluation of a nested reverse transcriptase PCR (RT-PCR) procedure for the detection of small round-structured viruses (SRSVs) in molluscan shellfish and the application of this assay for the detection of SRSVs in commercially produced shellfish and in shellfish implicated in outbreaks of gastroenteritis. The range of virus strains detected and the sensitivity of detection were evaluated by using a representative panel of 21 well-characterized SRSV strains. The nested RT-PCR detected 15 of 21 SRSVs, demonstrating that the assay detects a broad range of SRSVs including strains from both genogroup I and genogroup II. Seeding experiments showed the nested RT-PCR assay to be 10 to 1,000 times more sensitive than the single-round RT-PCR assay for the detection of SRSV in shellfish. SRSV-contaminated samples were identified by nested RT-PCR for shellfish grown in polluted harvesting areas and for shellfish associated with outbreaks of gastroenteritis which were negative by a previously described single-round RT-PCR. The assay was shown to be effective for investigation of virus elimination during commercial shellfish processing procedures such as depuration and relaying and has potential applications for monitoring at-risk shellfish harvesting areas, for investigation of SRSV contamination in shellfish from producers linked to gastroenteritis outbreaks, and for the direct detection of virus in shellfish implicated in outbreaks.
Purification and Characterization of Exo-β-
d
-Glucosaminidase from a Cellulolytic Fungus,
Trichoderma reesei
PC-3-7
Authors: Nogawa Masahiro , Takahashi Hiroya , Kashiwagi Aya , Ohshima Kenji , Okada Hirofumi , Morikawa Yasushi 
Published: December 2019

ABSTRACT

Chitosan-degrading activities induced by glucosamine (GlcN) or
N
-acetylglucosamine (GlcNAc) were found in a culture filtrate of
Trichoderma reesei
PC-3-7. One of the chitosan-degrading enzymes was purified to homogeneity by precipitation with ammonium sulfate followed by anion-exchange and hydrophobic-interaction chromatographies. The enzyme was monomeric, and its molecular mass was 93 kDa. The optimum pH and temperature of the enzyme were 4.0 and 50°C, respectively. The activity was stable in the pH range 6.0 to 9.0 and at a temperature below 50°C. Reaction product analysis from the viscosimetric assay and thin-layer chromatography and
1
H nuclear magnetic resonance spectroscopy clearly indicated that the enzyme was an exo-type chitosanase, exo-β-
d
-glucosaminidase, that releases GlcN from the nonreducing end of the chitosan chain.
1
H nuclear magnetic resonance spectroscopy also showed that the exo-β-
d
-glucosaminidase produced a β-form of GlcN, demonstrating that the enzyme is a retaining glycanase. Time-dependent liberation of the reducing sugar from partially acetylated chitosan with exo-β-
d
-glucosaminidase and the partially purified exo-β-
d
-
N
-acetylglucosaminidase from
T. reesei
PC-3-7 suggested that the exo-β-
d
-glucosaminidase cleaves the glycosidic link of either GlcN-β(1→4)-GlcN or GlcN-β(1→4)-GlcNAc.
Fermentation, Purification, and Characterization of Protective Antigen from a Recombinant, Avirulent Strain of
Bacillus anthracis
Authors: Farchaus J. W. , Ribot W. J. , Jendrek S. , Little S. F. 
Published: December 2019

ABSTRACT

Bacillus anthracis
, the etiologic agent for anthrax, produces two bipartite, AB-type exotoxins, edema toxin and lethal toxin. The B subunit of both exotoxins is an
M
r
83,000 protein termed protective antigen (PA). The human anthrax vaccine currently licensed for use in the United States consists primarily of this protein adsorbed onto aluminum oxyhydroxide. This report describes the production of PA from a recombinant, asporogenic, nontoxigenic, and nonencapsulated host strain of
B. anthracis
and the subsequent purification and characterization of the protein product. Fermentation in a high-tryptone, high-yeast-extract medium under nonlimiting aeration produced 20 to 30 mg of secreted PA per liter. Secreted protease activity under these fermentation conditions was low and was inhibited more than 95% by the addition of EDTA. A purity of 88 to 93% was achieved for PA by diafiltration and anion-exchange chromatography, while greater than 95% final purity was achieved with an additional hydrophobic interaction chromatography step. The purity of the PA product was characterized by reversed-phase high-pressure liquid chromatography, sodium dodecyl sulfate (SDS)-capillary electrophoresis, capillary isoelectric focusing, native gel electrophoresis, and SDS-polyacrylamide gel electrophoresis. The biological activity of the PA, when combined with excess lethal factor in the macrophage cell lysis assay, was comparable to previously reported values.
Differential Transmission of the Genospecies of
Borrelia burgdorferi
Sensu Lato by Game Birds and Small Rodents in England
Authors: Kurtenbach Klaus , Peacey Mick , Rijpkema Sjoerd G. T. , Hoodless Andrew N. , Nuttall Patricia A. , Randolph Sarah E. 
Published: December 2019

ABSTRACT

The genetic diversity of
Borrelia burgdorferi
sensu lato was assessed in a focus of Lyme borreliosis in southern Britain dominated by game birds. Ticks, rodents, and pheasants were analyzed for spirochete infections by PCR targeting the 23S-5S rRNA genes, followed by genotyping by the reverse line blot method. In questing
Ixodes ricinus
ticks, three genospecies of
B. burgdorferi
sensu lato were detected, with the highest prevalences found for
Borrelia garinii
and
Borrelia valaisiana. B. burgdorferi
sensu stricto was rare (<1%) in all tick stages.
Borrelia afzelii
was not detected in any of the samples. More than 50% of engorged nymphs collected from pheasants were infected with borreliae, mainly
B. garinii
and/or
B. valaisiana
. Although 19% of the rodents harbored
B. burgdorferi
sensu stricto and/or
B. garinii
in internal organs, only
B. burgdorferi
sensu stricto was transmitted to xenodiagnostic tick larvae (it was transmitted to 1% of the larvae). The data indicate that different genospecies of
B. burgdorferi
sensu lato can be maintained in nature by distinct transmission cycles involving the same vector tick species but different vertebrate host species. Wildlife management may have an influence on the relative risk of different clinical forms of Lyme borreliosis.
Enhancement of Exopolysaccharide Production by
Lactobacillus delbrueckii
subsp.
bulgaricus
NCFB 2772 with a Simplified Defined Medium
Authors: Grobben G. J. , Chin-Joe I. , Kitzen V. A. , Boels I. C. , Boer F. , Sikkema J. , Smith M. R. , de Bont J. A. M. 
Published: December 2019

ABSTRACT

The aim of this work was to investigate the medium requirements for growth and production of exopolysaccharides by
Lactobacillus delbrueckii
subsp.
bulgaricus
NCFB 2772. The strain was grown in batch cultures on a chemically defined medium, and the technique of single omission of medium components was applied to determine the nutritional requirements. The omission of aspartic acid, glutamic acid, or glycine affected growth only slightly, and the omission of glutamine, asparagine, or threonine resulted in a stronger reduction of the growth. All the other amino acids were essential. Multiple omissions of amino acids caused an almost complete loss of growth.
L. delbrueckii
subsp.
bulgaricus
required only riboflavin, calcium pantothenate, and nicotinic acid as individual vitamins. Surprisingly, when only these vitamins were present in the medium and other vitamins were not, less growth was observed than in the complete medium but the amount of exopolysaccharide produced was significantly greater. These observations were studied in more detail with a simplified defined medium in which
L. delbrueckii
subsp.
bulgaricus
was able to grow and produce exopolysaccharides. Although the final optical density in the simplified medium was lower, the production of exopolysaccharides was about twofold higher than in the complete medium.
Pichia stipitis
Genes for Alcohol Dehydrogenase with Fermentative and Respiratory Functions
Authors: Cho Jae-yong , Jeffries Thomas W. 
Published: December 2019

ABSTRACT

Two genes coding for isozymes of alcohol dehydrogenase (ADH); designated
PsADH1
and
PsADH2
, have been identified and isolated from
Pichia stipitis
CBS 6054 genomic DNA by Southern hybridization to
Saccharomyces cerevisiae ADH
genes, and their physiological roles have been characterized through disruption. The amino acid sequences of the PsADH1 and PsADH2 isozymes are 80.5% identical to one another and are 71.9 and 74.7% identical to the
S. cerevisiae
ADH1 protein. They also show a high level identity with the group I ADH proteins from
Kluyveromyces lactis
. The PsADH isozymes are presumably localized in the cytoplasm, as they do not possess the amino-terminal extension of mitochondrion-targeted ADHs. Gene disruption studies suggest that PsADH1 plays a major role in xylose fermentation because
PsADH1
disruption results in a lower growth rate and profoundly greater accumulation of xylitol. Disruption of
PsADH2
does not significantly affect ethanol production or aerobic growth on ethanol as long as
PsADH1
is present. The PsADH1 and PsADH2 isozymes appear to be equivalent in the ability to convert ethanol to acetaldehyde, and either is sufficient to allow cell growth on ethanol. However, disruption of both genes blocks growth on ethanol.
P. stipitis
strains disrupted in either
PsADH1
or
PsADH2
still accumulate ethanol, although in different amounts, when grown on xylose under oxygen-limited conditions. The
PsADH
double disruptant, which is unable to grow on ethanol, still produces ethanol from xylose at about 13% of the rate seen in the parental strain. Thus, deletion of both
PsADH1
and
PsADH2
blocks ethanol respiration but not production, implying a separate path for fermentation.
Purification and Characterization of a Nylon-Degrading Enzyme
Authors: Deguchi Tetsuya , Kitaoka Yoshihisa , Kakezawa Masaaki , Nishida Tomoaki 
Published: December 2019

ABSTRACT

A nylon-degrading enzyme found in the extracellular medium of a ligninolytic culture of the white rot fungus strain IZU-154 was purified by ion-exchange chromatography, gel filtration chromatography, and hydrophobic chromatography. The characteristics of the purified protein (i.e., molecular weight, absorption spectrum, and requirements for 2,6-dimethoxyphenol oxidation) were identical to those of manganese peroxidase, which was previously characterized as a key enzyme in the ligninolytic systems of many white rot fungi, and this result led us to conclude that nylon degradation is catalyzed by manganese peroxidase. However, the reaction mechanism for nylon degradation differed significantly from the reaction mechanism reported for manganese peroxidase. The nylon-degrading activity did not depend on exogenous H
2
O
2
but nevertheless was inhibited by catalase, and superoxide dismutase inhibited the nylon-degrading activity strongly. These features are identical to those of the peroxidase-oxidase reaction catalyzed by horseradish peroxidase. In addition, α-hydroxy acids which are known to accelerate the manganese peroxidase reaction inhibited the nylon-degrading activity strongly. Degradation of nylon-6 fiber was also investigated. Drastic and regular erosion in the nylon surface was observed, suggesting that nylon is degraded to soluble oligomers and that nylon is degraded selectively.
Synergism between
Bacillus thuringiensis
Spores and Toxins against Resistant and Susceptible Diamondback Moths (
Plutella xylostella
)
Authors: Liu Yong-Biao , Tabashnik Bruce E. , Moar William J. , Smith Robert A. 
Published: December 2019

ABSTRACT

We studied the effects of combinations of
Bacillus thuringiensis
spores and toxins on the mortality of diamondback moth (
Plutella xylostella
) larvae in leaf residue bioassays. Spores of
B. thuringiensis
subsp.
kurstaki
increased the toxicity of crystals of
B. thuringiensis
subsp.
kurstaki
to both resistant and susceptible larvae. For
B. thuringiensis
subsp.
kurstaki
, resistance ratios were 1,200 for a spore-crystal mixture and 56,000 for crystals without spores. Treatment of a spore-crystal formulation of
B. thuringiensis
subsp.
kurstaki
with the antibiotic streptomycin to inhibit spore germination reduced toxicity to resistant larvae but not to susceptible larvae. In contrast, analogous experiments with
B. thuringiensis
subsp.
aizawai
revealed no significant effects of adding spores to crystals or of treating a spore-crystal formulation with streptomycin. Synergism occurred between Cry2A and
B. thuringiensis
subsp.
kurstaki
spores against susceptible larvae and between Cry1C and
B. thuringiensis
subsp.
aizawai
spores against resistant and susceptible larvae. The results show that
B. thuringiensis
toxins combined with spores can be toxic even though the toxins and spores have little or no independent toxicity. Results reported here and previously suggest that, for diamondback moth larvae, the extent of synergism between spores and toxins of
B. thuringiensis
depends on the strain of insect, the type of spore, the set of toxins, the presence of other materials such as formulation ingredients, and the concentrations of spores and toxins.
Longitudinal Study ofEscherichia coliO157:H7 Dissemination on Four Dairy Farms in Wisconsin
Authors: Shere J. A. , Bartlett K. J. , Kaspar C. W. 
Published: December 2019

ABSTRACTA 14-month longitudinal study was conducted on four dairy farms (C, H, R, and X) in Wisconsin to ascertain the source(s) and dissemination ofEscherichia coliO157:H7. A cohort of 15 heifer calves from each farm were sampled weekly by digital rectal retrieval from birth to a minimum of 7 months of age (range, 7 to 13 months). Over the 14 months of the study, the cohort heifers and other randomly selected cattle from farms C and H tested negative. Farm R had two separate periods ofE. coliO157:H7 shedding lasting 4 months (November 1995 to February 1996) and 1 month (July to August 1996), while farm X had at least one positive cohort animal for a 5-month period (May to October 1996). Heifers shed O157:H7 strains in feces for 1 to 16 weeks at levels ranging from 2.0 × 102to 8.7 × 104CFU per g.E. coliO157:H7 was also isolated from other noncohort cattle, feed, flies, a pigeon, and water associated with the cohort heifers on farms R and/or X. When present in animal drinking water,E. coliO157:H7 disseminated through the cohort cattle and other cattle that used the water source.E. coliO157:H7 was found in water at <1 to 23 CFU/ml. Genomic subtyping by pulsed-field gel electrophoresis demonstrated that a single O157:H7 strain comprised a majority of the isolates from cohort and noncohort cattle, water, and other positive samples (i.e., from feed, flies, and a pigeon, etc.) on a farm. The isolates from farm R displayed two predominantXbaI restriction endonuclease digestion profiles (REDP), REDP 3 and REDP 7, during the first and second periods of shedding, respectively. Six additional REDP that were ≥89% similar to REDP 3 or REDP 7 were identified among the farm R isolates. Additionally, the REDP of an O157:H7 isolate from a heifer on farm R in 1994 was indistinguishable from REDP 3. Farm X had one O157:H7 strain that predominated (96% of positive samples had strains with REDP 9), and the REDP of an isolate from a heifer in 1994 was indistinguishable from REDP 9. These results suggest thatE. coliO157:H7 is disseminated from a common source on farms and that strains can persist in a herd for a 2-year period.
Cocoa Fermentations Conducted with a Defined Microbial Cocktail Inoculum
Authors: Schwan Rosane Freitas 
Published: December 2019

ABSTRACT

Cocoa fermentations were performed in wooden boxes under the following four experimental regimens: beans naturally fermented with wild microflora; aseptically prepared beans with no inoculum; and beans inoculated with a defined cocktail containing microorganisms at a suitable concentration either at zero time or by using phased additions at appropriate times. The cocktail used consisted of a yeast,
Saccharomyces cerevisiae
var.
chevalieri
, two lactic acid bacterial species,
Lactobacillus lactis
and
Lactobacillus plantarum
, and two acetic acid bacterial species,
Acetobacter aceti
and
Gluconobacter oxydans
subsp.
suboxydans
. The parameters measured were cell counts (for yeasts, filamentous fungi, lactic acid bacteria, acetic acid bacteria, and spore formers, including reisolation and identification of all residual cell types), sugar, ethanol, acetic acid, and lactic acid contents (and contents of other organic acids), pH, and temperature. A cut test for bean quality and a sensorial analysis of chocolate made from the beans were also performed. The natural fermentation mimicked exactly the conditions in 800-kg boxes on farms. The aseptic box remained largely free of microflora throughout the study, and no significant biochemical changes occurred. With the zero-time inoculum the fermentation was almost identical to the natural fermentation. The fermentation with the phased-addition inoculum was similar, but many changes in parameters were slower and less pronounced, which led to a slightly poorer end product. The data show that the nearly 50 common species of microorganisms found in natural fermentations can be replaced by a judicious selection and concentration of members of each physiological group. This is the first report of successful use of a defined, mixed starter culture in such a complex fermentation, and it should lead to chocolate of more reliable and better quality.