bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of a Sentinel System for Field Measurements ofCryptosporidium parvumOocyst Inactivation in Soil and Animal Waste
Authors: Jenkins M. B. , Walker M. J. , Bowman D. D. , Anthony L. C. , Ghiorse W. C. 
Published: December 2019

ABSTRACTA small-volume sentinel chamber was developed to assess the effects of environmental stresses on survival of sucrose-Percoll-purifiedCryptosporidium parvumoocysts in soil and animal wastes. Chambers were tested for their ability to equilibrate with external chemical and moisture conditions. Sentinel oocysts were then exposed to stresses of the external environment that affected their viability (potential infectivity), as indicated by results of a dye permeability assay. Preliminary laboratory experiments indicated that temperatures between 35 and 50°C and decreases in soil water potential (−0.003 to −3.20 MPa) increased oocyst inactivation rates. The effects of two common animal waste management practices on oocyst survival were investigated on three dairy farms in Delaware County, N.Y., within the New York City watershed: (i) piling wastes from dairy youngstock (including neonatal calves) and (ii) spreading wastes as a soil amendment on an agricultural field. Sentinel containers filled with air-dried and sieved (2-mm mesh) youngstock waste or field soil were wetted and inoculated with 2 million oocysts in an aqueous suspension and then placed in waste piles on two different farms and in soil within a cropped field on one farm. Controls consisted of purified oocysts in either phosphate-buffered saline or distilled water contained in sealed microcentrifuge tubes. Two microdata loggers recorded the ambient temperature at each field site. Sentinel experiments were conducted during the fall and winter (1996 to 1997) and winter (1998). Sentinel containers and controls were removed at 2- to 4-week intervals, and oocysts were extracted and tested by the dye permeability assay. The proportions of potentially infective oocysts exposed to the soil and waste pile material decreased more rapidly than their counterpart controls exposed to buffer or water, indicating that factors other than temperature affected oocyst inactivation in the waste piles and soil. The effect of soil freeze-thaw cycles was evident in the large proportion of empty sentinel oocysts. The potentially infective sentinel oocysts were reduced to <1% while the proportions in controls did not decrease below 50% potentially infective during the first field experiment. Microscopic observations of empty oocyst fragments indicated that abrasive effects of soil particles were a factor in oocyst inactivation. A similar pattern was observed in a second field experiment at the same site.
Division of
Listeria monocytogenes
Serovar 1/2a Strains into Two Groups by PCR and Restriction Enzyme Analysis
Authors: Unnerstad Helle , Nilsson Inger , Ericsson Henrik , Danielsson-Tham Marie-Louise , Bille Jacques , Bannerman Elizabeth , Tham Wilhelm 
Published: December 2019

ABSTRACT

Altogether, 100 strains of
Listeria monocytogenes
serovar 1/2a isolated from humans, animals, food, and the environment were typed by a combination of PCR and restriction enzyme analysis (REA). A PCR product of 2,916 bp, containing the downstream end of the gene
inlA
(955 bp), the space between
inlA
and
inlB
(85 bp), and 1,876 bp of the gene
inlB
, was cleaved with the enzyme
Alu
I, and the fragments generated were separated by gel electrophoresis. By this method two different cleavage patterns were obtained. Seventy of the 100 strains shared one restriction profile, and the remaining 30 strains shared the second one. No relation was found between the types differentiated by PCR-REA and the origins of the strains.
Localized, Positive Charge Mediates Adhesion of
Rhodosporidium toruloides
to Barley Leaves and Polystyrene
Authors: Buck James W. , Andrews John H. 
Published: December 2019

ABSTRACT

The physicochemical forces that mediate attachment of yeasts to the phylloplane are unknown. Cell surface charge and hydrophobicity and adhesion to polystyrene, glass, and barley were assessed for wild-type
Rhodosporidium toruloides
and attachment-minus (Att
−
) mutants. Cells were grown under conditions promoting (excess carbon) or not promoting (excess nitrogen) capsule production. Hydrophobicity was measured by adhesion to xylenes, and surface charge characteristics were assessed by attachment to either DEAE (positive)- or carboxymethyl (CM) (negative)-Sephadex ion-exchange beads. Hydrophobicity and adhesiveness of nonencapsulated, wild-type
R. toruloides
decreased from mid-log to late stationary phase. Encapsulated wild-type
R. toruloides
cells were more hydrophobic and more adhesive than nonencapsulated cells. However, two encapsulated Att
−
mutants were more hydrophobic than the wild type and levels of adhesion of
R. toruloides
were similar on polystyrene and less hydrophobic glass surfaces. Adhesion of wild-type yeast to barley and polystyrene was correlated with attachment to CM-Sephadex beads, indicating a positive cell surface charge. Sixteen Att
−
mutants did not exhibit a positive cell surface charge, and wild-type yeast cells that did not attach to CM-Sephadex did not adhere to either polystyrene or barley. Wild-type
R. toruloides
attached to CM-Sephadex beads by the poles of the cells, indicating a localization of positive charge which was also visualized with India ink. We conclude that localized, positive charge, and not hydrophobic interactions, mediates attachment of
R. toruloides
to barley leaves.
Excision of the Conjugative Transposon Tn
916
in
Lactococcus lactis
Authors: Marra Diana , Smith Jennifer G. , Scott June R. 
Published: December 2019

ABSTRACT

In
Lactococcus lactis
excision of Tn
916
is limited by the concentration of integrase and is increased by providing more excisionase. However, even with increased excision of Tn
916
in
L. lactis
, no conjugative transfer is detectable. This suggests that
L. lactis
is deficient in a host factor(s) required for conjugative transposition.
Methods for Detection of
Anticarsia gemmatalis
Nucleopolyhedrovirus DNA in Soil
Authors: de Moraes R. R. , Maruniak J. E. , Funderburk J. E. 
Published: December 2019

ABSTRACT

Two methods, phenol-ether and magnetic capture-hybridization (MCH), were developed and compared with regard to their sensitivities and abilities to extract the DNA of the insect baculovirus
Anticarsia gemmatalis
nucleopolyhedrovirus (Ag
M
NPV) from soil and to produce DNA amplifiable by PCR. Laboratory experiments were performed with 0.25 g of autoclaved soil inoculated with different viral concentrations to optimize both methods of baculovirus DNA extraction and to determine their sensitivities. Both procedures produced amplifiable DNA; however, the MCH method was 100-fold more sensitive than the phenol-ether procedure. The removal of PCR inhibitors from the soil appeared to be complete when MCH was used as the viral DNA isolation method, because undiluted aliquots of the DNA preparations could be amplified by PCR. The phenol-ether procedure probably did not completely remove PCR inhibitors from the soil, since PCR products were observed only when the Ag
M
NPV DNA preparations were diluted 10- or 100-fold. Ag
M
NPV DNA was detected in field-collected soil samples from 15 to 180 days after virus application when the MCH procedure to isolate DNA was coupled with PCR amplification of the polyhedrin region.
Quantitative Immunofluorescence of Regulated
eps
Gene Expression in Single Cells of
Ralstonia solanacearum
Authors: Kang Yaowei , Saile Elke , Schell Mark A. , Denny Timothy P. 
Published: December 2019

ABSTRACT

Ralstonia solanacearum
, a phytopathogenic bacterium, uses an environmentally sensitive and complex regulatory network to control expression of multiple virulence genes. Part of this network is an unusual autoregulatory system that produces and senses 3-hydroxypalmitic acid methyl ester. In culture, this autoregulatory system ensures that expression of virulence genes, such as those of the
eps
operon encoding biosynthesis of the acidic extracellular polysaccharide, occurs only at high cell density (>10
7
cells/ml). To determine if regulation follows a similar pattern within tomato plants, we first developed a quantitative immunofluorescence (QIF) method that measures the relative amount of a target protein within individual bacterial cells. For
R. solanacearum
, QIF was used to determine the amount of β-galactosidase protein within wild-type cells containing a stable
eps-lacZ
reporter allele. When cultured cells were examined to test the method, QIF accurately detected both low and high levels of
eps
gene expression. QIF analysis of
R. solanacearum
cells recovered from stems of infected tomato plants showed that expression of
eps
during pathogenesis was similar to that in culture. These results suggest that there are no special signals or conditions within plants that override or short-circuit the regulatory processes observed in
R. solanacearum
in culture. Because QIF is a robust, relatively simple procedure that uses generally accessible equipment, it should be useful in many situations where gene expression in single bacterial cells must be determined.
Deletions in the Gibberellin Biosynthesis Gene Cluster of
Gibberella fujikuroi
by Restriction Enzyme-Mediated Integration and Conventional Transformation-Mediated Mutagenesis
Authors: Linnemannstöns Pia , Voß Thorsten , Hedden Peter , Gaskin Paul , Tudzynski Bettina 
Published: December 2019

ABSTRACT

We induced mutants of
Gibberella fujikuroi
deficient in gibberellin (GA) biosynthesis by transformation-mediated mutagenesis with the vector pAN7-1. We recovered 24 GA-defective mutants in one of nine transformation experiments performed without the addition of a restriction enzyme. Each mutant had a similar Southern blot pattern, suggesting the integration of the vector into the same site. The addition of a restriction enzyme by restriction enzyme-mediated integration (REMI) significantly increased the transformation rate and the rate of single-copy integration events. Of 1,600 REMI transformants, two produced no GAs. Both mutants had multiple copies of the vector pAN7-1 and one had a Southern blot pattern similar to those of the 24 conventionally transformed GA-deficient mutants. Biochemical analysis of the two REMI mutants confirmed that they cannot produce
ent
-kaurene, the first specific intermediate of the GA pathway. Feeding the radioactively labelled precursors
ent
-kaurene and GA
12
-aldehyde followed by high-performance liquid chromatography and gas chromatography-mass spectrometry analysis showed that neither of these intermediates was converted to GAs in the mutants. Southern blot analysis and pulsed-field gel electrophoresis of the transformants using the bifunctional
ent
-copalyl diphosphate/
ent
-kaurene synthase gene (
cps/ks
) and the flanking regions as probes revealed a large deletion in the GA-deficient REMI transformants and in the GA-deficient transformants obtained by conventional insertional transformation. We conclude that transformation procedures with and without the addition of restriction enzymes can lead to insertion-mediated mutations and to deletions and chromosome translocations.
Purification and Characterization of a Keratinolytic Serine Proteinase from
Streptomyces albidoflavus
Authors: Bressollier Philippe , Letourneau François , Urdaci Maria , Verneuil Bernard 
Published: December 2019

ABSTRACT

Streptomyces
strain K
1-02
, which was identified as a strain of
Streptomyces albidoflavus
, secreted at least six extracellular proteases when it was cultured on feather meal-based medium. The major keratinolytic serine proteinase was purified to homogeneity by a two-step procedure. This enzyme had a molecular weight of 18,000 and was optimally active at pH values ranging from 6 to 9.5 and at temperatures ranging from 40 to 70°C. Its sensitivity to protease inhibitors, its specificity on synthetic substrates, and its remarkably high level of NH
2
-terminal sequence homology with
Streptomyces griseus
protease B (SGPB) showed that the new enzyme, designated SAKase, was homologous to SGPB. We tested the activity of SAKase with soluble and fibrous substrates (elastin, keratin, and type I collagen) and found that it was very specific for keratinous substrates compared to SGPB and proteinase K.
Nitrous Oxide Production and Methane Oxidation by Different Ammonia-Oxidizing Bacteria
Authors: Jiang Qing-Qiao , Bakken Lars R. 
Published: December 2019

ABSTRACT

Ammonia-oxidizing bacteria (AOB) are thought to contribute significantly to N
2
O production and methane oxidation in soils. Most of our knowledge derives from experiments with
Nitrosomonas europaea
, which appears to be of minor importance in most soils compared to
Nitrosospira
spp. We have conducted a comparative study of levels of aerobic N
2
O production in six phylogenetically different
Nitrosospira
strains newly isolated from soils and in two
N. europaea
and
Nitrosospira multiformis
type strains. The fraction of oxidized ammonium released as N
2
O during aerobic growth was remarkably constant (0.07 to 0.1%) for all the
Nitrosospira
strains, irrespective of the substrate supply (urea versus ammonium), the pH, or substrate limitation.
N. europaea
and
Nitrosospira multiformis
released similar fractions of N
2
O when they were supplied with ample amounts of substrates, but the fractions rose sharply (to 1 to 5%) when they were restricted by a low pH or substrate limitation. Phosphate buffer (versus HEPES) doubled the N
2
O release for all types of AOB. No detectable oxidation of atmospheric methane was detected. Calculations based on detection limits as well as data in the literature on CH
4
oxidation by AOB bacteria prove that none of the tested strains contribute significantly to the oxidation of atmospheric CH
4
in soils.
Piriformospora indica
, a Cultivable Plant-Growth-Promoting Root Endophyte
Authors: Varma Ajit , Savita Verma  , Sudha  , Sahay Nirmal , Bütehorn Britta , Franken Philipp 
Published: December 2019

ABSTRACT

Piriformospora indica
(Hymenomycetes, Basidiomycota) is a newly described cultivable endophyte that colonizes roots. Inoculation with the fungus and application of fungal culture filtrate promotes plant growth and biomass production. Due to its ease of culture, this fungus provides a model organism for the study of beneficial plant-microbe interactions and a new tool for improving plant production systems.
Influence of Temperature and Growth Phase on Expression of a 104-Kilodalton
Listeria
Adhesion Protein in
Listeria monocytogenes
Authors: Santiago Nivia I. , Zipf Allan , Bhunia Arun K. 
Published: December 2019

ABSTRACT

Interaction of
Listeria monocytogenes
with mammalian intestinal cells is believed to be an important first step in
Listeria
pathogenesis. Transposon (Tn
916
) mutagenesis provided strong evidence that a 104-kDa surface protein, designated the
Listeria
adhesion protein (LAP), was involved in adherence of
L. monocytogenes
to a human enterocyte-like Caco-2 cell line (V. Pandiripally, D. Westbrook, G. Sunki, and A. Bhunia, J. Med. Microbiol. 48:117–124, 1999). In this study, expression of LAP in
L. monocytogenes
at various growth temperatures (25, 37, and 42°C) and in various growth phases was determined by performing an enzyme-linked immunoassay (ELISA) and Western blotting with a specific monoclonal antibody (monoclonal antibody H7). The ELISA and Western blot results indicated that there was a significant increase in LAP expression over time only at 37 and 42°C and that the level of LAP expression was low during the exponential phase and high during the stationary phase. In contrast, there were not significant differences in LAP expression between the exponential and stationary phases at 25°C. Examination of the adhesion of
L. monocytogenes
cells from exponential-phase (12-h) or stationary-phase (24-h) cultures grown at 37°C to Caco-2 cells revealed that there were not significant differences in adhesion. Although expression of
L. monocytogenes
LAP was different at different growth temperatures and in different growth phases, enhanced expression did not result in increased adhesion, possibly because only a few LAP molecules were sufficient to initiate binding to Caco-2 cells.
Multiple Antibiotic Resistance Patterns of
Escherichia coli
Isolates from Swine Farms
Authors: Mathew A. G. , Saxton A. M. , Upchurch W. G. , Chattin S. E. 
Published: December 2019

ABSTRACT

Antibiotic resistance of
Escherichia coli
from sows and pigs was determined to compare patterns between pigs of various ages and degrees of antibiotic use. Resistance patterns differed between farm types and pigs of differing ages, indicating that pig age and degree of antibiotic use affect resistance of fecal
E. coli
.
Response of Pathogenic
Vibrio
Species to High Hydrostatic Pressure
Authors: Berlin Daniel L. , Herson Diane S. , Hicks Doris T. , Hoover Dallas G. 
Published: December 2019

ABSTRACT

Vibrio parahaemolyticus
ATCC 17802,
Vibrio vulnificus
ATCC 27562,
Vibrio cholerae
O:1 ATCC 14035,
Vibrio cholerae
non-O:1 ATCC 14547,
Vibrio hollisae
ATCC 33564, and
Vibrio mimicus
ATCC 33653 were treated with 200 to 300 MPa for 5 to 15 min at 25°C. High hydrostatic pressure inactivated all strains of pathogenic
Vibrio
without triggering a viable but nonculturable (VBNC) state; however, cells already existing in a VBNC state appeared to possess greater pressure resistance.
A New Biocatalyst for Production of Optically Pure Aryl Epoxides by Styrene Monooxygenase from
Pseudomonas fluorescens
ST
Authors: Di Gennaro Patrizia , Colmegna Andrea , Galli Enrica , Sello Guido , Pelizzoni Francesca , Bestetti Giuseppina 
Published: December 2019

ABSTRACT

We developed a biocatalyst by cloning the styrene monooxygenase genes (
styA
and
styB
) from
Pseudomonas fluorescens
ST responsible for the oxidation of styrene to its corresponding epoxide. Recombinant
Escherichia coli
was able to oxidize different aryl vinyl and aryl ethenyl compounds to their corresponding optically pure epoxides. The results of bioconversions indicate the broad substrate preference of styrene monooxygenase and its potential for the production of several fine chemicals.
Production of Monoclonal Antibodies to
Listeria monocytogenes
and Their Application To Determine the Virulence of Isolates from Channel Catfish
Authors: Erdenlig Sevil , Ainsworth A. Jerald , Austin Frank W. 
Published: December 2019

ABSTRACT

We produced monoclonal antibodies (MAbs) to the extracellular proteins of
Listeria monocytogenes
EGD grown in Chelex-treated improved minimal medium. Ten of the positive hybridomas generated were chosen for further characterization. Seven of the MAbs reacted with a protein having a molecular mass of 60 kDa. These MAbs inhibited listeriolysin (LLO)-mediated hemolysis, and two of them were specific for LLO and none of the other thiol-activated toxins tested. In an enzyme-linked immunosorbent assay and Western blot analysis, five of the anti-LLO MAbs reacted with ivanolysin from
Listeria ivanovii
. Three of the 10 MAbs reacted with a 29-kDa protein on Western blots and neutralized the phosphatidylcholine-specific phospholipase C (PC-PLC) activity of
L. monocytogenes
. These three anti-PC-PLC MAbs did not react with phospholipases from five different gram-positive bacteria. However, the anti-PC-PLC MAbs recognized a 27-kDa extracellular protein from
L. ivanovii
and neutralized sphingomyelinase activity in a hemolysis test that demonstrates the antigenic relatedness of listerial phospholipases. These data indicate that listerial thiol-activated toxins possess species-specific epitopes and share group-specific epitopes. This is the first description of MAbs that neutralize listerial PC-PLC, and the data suggest that there is antigenic similarity between
L. monocytogenes
PC-PLC and
L. ivanovii
sphingomyelinase. The reactions of the MAbs with catfish isolates of
L. monocytogenes
suggested that some of the isolates examined lack the LLO and/or PC-PLC required for pathogenicity. The MAbs described here differentiated some catfish isolates from previously described type strain-pathogenic isolates and could be useful for detecting and determining the virulence of
L. monocytogenes
in food and clinical samples and for detecting
L. ivanovii
in veterinary clinical samples.
Stress Tolerance in Doughs of
Saccharomyces cerevisiae
Trehalase Mutants Derived from Commercial Baker’s Yeast
Authors: Shima Jun , Hino Akihiro , Yamada-Iyo Chie , Suzuki Yasuo , Nakajima Ryouichi , Watanabe Hajime , Mori Katsumi , Takano Hiroyuki 
Published: December 2019

ABSTRACT

Accumulation of trehalose is widely believed to be a critical determinant in improving the stress tolerance of the yeast
Saccharomyces cerevisiae
, which is commonly used in commercial bread dough. To retain the accumulation of trehalose in yeast cells, we constructed, for the first time, diploid homozygous neutral trehalase mutants (Δ
nth1
), acid trehalase mutants (Δ
ath1
), and double mutants (Δ
nth1 ath1
) by using commercial baker’s yeast strains as the parent strains and the gene disruption method. During fermentation in a liquid fermentation medium, degradation of intracellular trehalose was inhibited with all of the trehalase mutants. The gassing power of frozen doughs made with these mutants was greater than the gassing power of doughs made with the parent strains. The Δ
nth1
and Δ
ath1
strains also exhibited higher levels of tolerance of dry conditions than the parent strains exhibited; however, the Δ
nth1 ath1
strain exhibited lower tolerance of dry conditions than the parent strain exhibited. The improved freeze tolerance exhibited by all of the trehalase mutants may make these strains useful in frozen dough.
Interaction between Functional Domains of
Bacillus thuringiensis
Insecticidal Crystal Proteins
Authors: Rang Cécile , Vachon Vincent , de Maagd Ruud A. , Villalon Mario , Schwartz Jean-Louis , Bosch Dirk , Frutos Roger , Laprade Raynald 
Published: December 2019

ABSTRACT

Interactions among the three structural domains of
Bacillus thuringiensis
Cry1 toxins were investigated by functional analysis of chimeric proteins. Hybrid genes were prepared by exchanging the regions coding for either domain I or domain III among Cry1Ab, Cry1Ac, Cry1C, and Cry1E. The activity of the purified trypsin-activated chimeric toxins was evaluated by testing their effects on the viability and plasma membrane permeability of Sf9 cells. Among the parental toxins, only Cry1C was active against these cells and only chimeras possessing domain II from Cry1C were functional. Combination of domain I from Cry1E with domains II and III from Cry1C, however, resulted in an inactive toxin, indicating that domain II from an active toxin is necessary, but not sufficient, for activity. Pores formed by chimeric toxins in which domain I was from Cry1Ab or Cry1Ac were slightly smaller than those formed by toxins in which domain I was from Cry1C. The properties of the pores formed by the chimeras are therefore likely to result from an interaction between domain I and domain II or III. Domain III appears to modulate the activity of the chimeric toxins: combination of domain III from Cry1Ab with domains I and II of Cry1C gave a protein which was more strongly active than Cry1C.