bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatial and Temporal Deposition of Adhesive Extracellular Polysaccharide Capsule and Fimbriae by
Hyphomonas
Strain MHS-3
Authors: Quintero Ernesto J. , Busch Kathryn , Weiner Ronald M. 
Published: December 2019

ABSTRACT

Hyphomonas
strain MHS-3, a member of a genus of primary colonizers of surfaces immersed in marine water, synthesizes two structures that mediate adhesion to solid substrata, namely, capsular exopolysaccharide and fimbriae. Specific stains, gold-labelled lectins, and monoclonal antibodies, along with transmission electron microscopy of synchronized populations, revealed that both structures are polarly and temporally expressed. The timed synthesis and placement of the fimbriae and capsule correlated with the timing and locus of MHS-3 adhesion.
Biodegradation of Metal-EDTA Complexes by an Enriched Microbial Population
Authors: Thomas Russell A. P. , Lawlor Kirsten , Bailey Mark , Macaskie Lynne E. 
Published: December 2019

ABSTRACT

A mixed culture utilizing EDTA as the sole carbon source was isolated from a mixed inoculum of water from the River Mersey (United Kingdom) and sludge from an industrial effluent treatment plant. Fourteen component organisms were isolated from the culture, including representatives of the genera
Methylobacterium
,
Variovorax
,
Enterobacter
,
Aureobacterium
, and
Bacillus
. The mixed culture biodegraded metal-EDTA complexes slowly; the biodegradability was in the order Fe>Cu>Co>Ni>Cd. By incorporation of inorganic phosphate into the medium as a precipitant ligand, heavy metals were removed in parallel to EDTA degradation. The mixed culture also utilized a number of possible EDTA degradation intermediates as carbon sources.
Bacterial Oxidation of Mercury Metal Vapor, Hg(0)
Authors: Smith Tracy , Pitts Keith , McGarvey Jeffery A. , Summers Anne O. 
Published: December 2019

ABSTRACT

We used metalloregulated luciferase reporter fusions and spectroscopic quantification of soluble Hg(II) to determine that the hydroperoxidase-catalase, KatG, of
Escherichia coli
can oxidize monatomic elemental mercury vapor, Hg(0), to the water-soluble, ionic form, Hg(II). A strain with a mutation in
katG
and a strain overproducing KatG were used to demonstrate that the amount of Hg(II) formed is proportional to the catalase activity. Hg(0) oxidation was much decreased in stationary-phase cells of a strain lacking KatG, suggesting that the monofunctional hydroperoxidase KatE is less effective at this reaction. Unexpectedly, Hg(0) oxidation also occurred in a strain lacking both KatE and KatG, suggesting that activities other than hydroperoxidases may carry out this reaction. Two typical soil bacteria,
Bacillus
and
Streptomyces
, also oxidize Hg(0) to Hg(II). These observations establish for the first time that bacteria can contribute, as do mammals and plants, to the oxidative phase of the global Hg cycle.
Temperature and Sporulation of Aquatic Hyphomycetes
Authors: Chauvet Eric , Suberkropp Keller 
Published: December 2019

ABSTRACT

Temperature appears to be an important factor affecting the occurrence and distribution of aquatic hyphomycetes, the dominant leaf litter-decomposing fungi in streams. We compared conidium production by eight species of aquatic hyphomycetes grown on yellow poplar leaves in stream-simulating microcosms at three temperatures (15, 20, and 25°C). The greatest conidium production occurred at 15°C for one species, 20°C for two species, and 25°C for two species. Two species produced similar numbers of conidia at 20 and 25°C, and one species produced similar numbers of conidia at all three temperatures. Linear growth rates were determined on malt extract agar. Six species had the same pattern of temperature responses for growth on malt extract agar as for sporulation on leaves, as shown by the positive correlations between the two parameters at the three temperatures. The species examined also exhibited differences in number of conidia produced from a similar amount of leaf material at a given temperature. These differences appeared to be due primarily to differences in individual conidium mass (determined by weighing conidia produced from cultures), as shown by the relationship of the type
Y = k/X
(
r
2
= 0.96), where
Y
is the number of conidia produced,
X
is the individual conidium mass in milligrams, and
k
is a constant empirically determined to be 2.11. This finding supports the hypothesis that aquatic hyphomycetes allocate similar amounts of their resources to reproduction but vary with respect how these resources are partitioned into reproductive units (conidia).
Enterohemorrhagic
Escherichia coli
O157:H7 Present in Radish Sprouts
Authors: Itoh Yoshinori , Sugita-Konishi Yoshiko , Kasuga Fumiko , Iwaki Masaaki , Hara-Kudo Yukiko , Saito Noriko , Noguchi Yoko , Konuma Hirotaka , Kumagai Susumu 
Published: December 2019

ABSTRACT

Using cultivation, immunofluorescence microscopy, and scanning electron microscopy, we demonstrated the presence of viable enterohemorrhagic
Escherichia coli
O157:H7 not only on the outer surfaces but also in the inner tissues and stomata of cotyledons of radish sprouts grown from seeds experimentally contaminated with the bacterium. HgCl
2
treatment of the outer surface of the hypocotyl did not kill the contaminating bacteria, which emphasized the importance of either using seeds free from
E. coli
O157:H7 in the production of radish sprouts or heating the sprouts before they are eaten.
Development of a Direct In Situ PCR Method for Detection of Specific Bacteria in Natural Environments
Authors: Tani Katsuji , Kurokawa Ken , Nasu Masao 
Published: December 2019

ABSTRACT

We applied HNPP (2-hydroxy-3-naphthoic acid-2′-phenylanilide phosphate) to direct in situ PCR for the routine detection of specific bacterial cells at the single-cell level. PCR was performed on glass slides with digoxigenin-labeled dUTP. The digoxigenin-labeled PCR products were detected with alkaline phosphatase-labeled antidigoxigenin antibody and HNPP which was combined with Fast Red TR. A bright red fluorescent signal was produced from conversion to HNP (dephosphorylated form) by alkaline phosphatase. We used the ECOL DNA primer set for amplification of ribosomal DNA of
Escherichia coli
to identify cells specifically at the single-cell level in a bacterial mixture. High-contrast images were obtained under an epifluorescence microscope with in situ PCR. By image analysis,
E. coli
cells in polluted river water also were detected.
An Origin of Transfer (
oriT
) on the Conjugative Element pRS01 from
Lactococcus lactis
subsp.
lactis
ML3
Authors: Mills David A. , Phister Trevor G. , Dunny Gary M. , McKay Larry L. 
Published: December 2019

ABSTRACT

Previous analysis of the Tra1 region of the conjugative element pRS01 from
Lactococcus lactis
subsp.
lactis
ML3 suggested that an origin of transfer (
oriT
) was present. Deletion derivatives of this cloned Tra1 region were assayed for mobilization in the presence of the wild-type pRS01 element in
trans
. The pRS01
oriT
was localized to a 446-nucleotide segment in the intergenic region between open reading frames
ltrD
and
ltrE
. Sequence analysis of this region revealed a cluster of direct and inverted repeat structures characteristic of
oriT
regions associated with other conjugative systems.
Laser Microsurgery Permits Fungal Plasma Membrane Single-Ion-Channel Resolution at the Hyphal Tip
Authors: Véry Anne-Aliénor , Davies Julia M. 
Published: December 2019

ABSTRACT

A method for formation of high-electrical-resistance seals on the
Neurospora crassa
plasma membrane, allowing resolution of single-ion-channel activity by patch clamp electrophysiology, is reported. Laser microsurgery permits access to the hyphal apex without enzymatic cell wall digestion and loss of morphological polarity. Cell wall reformation is delayed by brefeldin. This method can allow full characterization of apical plasma membrane channels, which are implicated in tip growth.
Characterization of Laccases and Peroxidases from Wood-Rotting Fungi (FamilyCoprinaceae)
Authors: Heinzkill Marion , Bech Lisbeth , Halkier Torben , Schneider Palle , Anke Timm 
Published: December 2019

ABSTRACTPanaeolus sphinctrinus,Panaeolus papilionaceus, andCoprinus friesiiare described as producers of ligninolytic enzymes.P. papilionaceusandP. sphinctrinusboth produced a laccase. In addition,P. sphinctrinusproduced a manganese peroxidase.C. friesiisecreted a laccase and two peroxidases similar to the peroxidase ofCoprinus cinereus. The purified laccases and peroxidases were characterized by broad substrate specificities, significant enzyme activities at alkaline pH values, and remarkably high pH optima. The two peroxidases ofC. friesiiremained active at pH 7.0 and 60°C for up to 60 min of incubation. The peroxidases were inhibited by sodium azide and ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA), whereas the laccases were inhibited by sodium azide andN,N-diethyldithiocarbamic acid. As determined by native polyacrylamide gel electrophoresis and isoelectric focusing, all three fungi produced laccase isoenzymes.
Overproduction of
l
-Cysteine and
l
-Cystine by
Escherichia coli
Strains with a Genetically Altered Serine Acetyltransferase
Authors: Nakamori Shigeru , Kobayashi Shin-ichiro , Kobayashi Chitose , Takagi Hiroshi 
Published: December 2019

ABSTRACT

Organisms that overproduced
l
-cysteine and
l
-cystine from glucose were constructed by using
Escherichia coli
K-12 strains.
cysE
genes coding for altered serine acetyltransferase, which was genetically desensitized to feedback inhibition by
l
-cysteine, were constructed by replacing the methionine residue at position 256 of the serine acetyltransferase protein with 19 other amino acid residues or the termination codon to truncate the carboxy terminus from amino acid residues 256 to 273 through site-directed mutagenesis by using PCR. A cysteine auxotroph, strain JM39, was transformed with plasmids having these altered
cysE
genes. The serine acetyltransferase activities of most of the transformants, which were selected based on restored cysteine requirements and ampicillin resistance, were less sensitive than the serine acetyltransferase activity of the wild type to feedback inhibition by
l
-cysteine. At the same time, these transformants produced approximately 200 mg of
l
-cysteine plus
l
-cystine per liter, whereas these amino acids were not detected in the recombinant strain carrying the wild-type serine acetyltransferase gene. However, the production of
l
-cysteine and
l
-cystine by the transformants was very unstable, presumably due to a cysteine-degrading enzyme of the host, such as cysteine desulfhydrase. Therefore, mutants that did not utilize cysteine were derived from host strain JM39 by mutagenesis with
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine. When a newly derived host was transformed with plasmids having the altered
cysE
genes, we found that the production of
l
-cysteine plus
l
-cystine was markedly increased compared to production in JM39.
High Levels of Endemicity of 3-Chlorobenzoate-Degrading Soil Bacteria
Authors: Fulthorpe R. R. , Rhodes A. N. , Tiedje J. M. 
Published: December 2019

ABSTRACT
Soils samples were obtained from pristine ecosystems in six regions on five continents. Two of the regions were boreal forests, and the other four were Mediterranean ecosystems. Twenty-four soil samples from each of four or five sites in each of the regions were enriched by using 3-chlorobenzoate (3CBA), and 3CBA mineralizers were isolated from most samples. These isolates were analyzed for the ability to mineralize 3CBA, and genotypes were determined with repetitive extragenic palindromic PCR genomic fingerprints and restriction digests of the 16S rRNA genes (amplified ribosomal DNA restriction analysis [ARDRA]). We found that our collection of 150 stable 3CBA-mineralizing isolates included 48 genotypes and 44 ARDRA types, which formed seven distinct clusters. The majority (91%) of the genotypes were unique to the sites from which they were isolated, and each genotype was found only in the region from which it was isolated. A total of 43 of the 44 ARDRA types were found in only one region. A few genotypes were repeatedly found in one region but not in any other continental region, suggesting that they are regionally endemic. A correlation between bacterial genotype and vegetative community was found for the South African samples. These results suggest that the ability to mineralize 3CBA is distributed among very diverse genotypes and that the genotypes are not globally dispersed.
Heterobinary Adhesins Based on the
Escherichia coli
FimH Fimbrial Protein
Authors: Schembri Mark A. , Klemm Per 
Published: December 2019

ABSTRACT

The FimH adhesin of
Escherichia coli
type 1 fimbriae confers the ability to bind to
d
-mannosides by virtue of a receptor-binding domain located in its N-terminal region. This protein was engineered into a heterobifunctional adhesin by introducing a secondary binding site in the C-terminal region. The insertion of histidine clusters into this site resulted in coordination of various metal ions by recombinant cells expressing chimeric FimH proteins. In addition, libraries consisting of random peptide sequences inserted into the FimH display system and screened by a “panning” technique were used to identify specific sequences conferring the ability to adhere to Ni
2+
and Cu
2+
. Recombinant cells expressing heterobifunctional FimH adhesins could adhere simultaneously to both metals and saccharides. Finally, combining the metal-binding modifications with alterations in the natural receptor-binding region demonstrated the ability to independently modulate the binding of FimH to two ligands simultaneously.
A Rapid PCR-Based DNA Test for Enterotoxic
Bacillus cereus
Authors: Mäntynen Vesa , Lindström Kristina 
Published: December 2019

ABSTRACT

The occurrence of DNA sequences encoding the hemolysin HblA complex and
Bacillus cereus
enterotoxin BceT, which have recently been confirmed as enterotoxins, was studied in
Bacillus
spp. To amplify these DNA sequences, PCR primer systems for the B component of
hblA
and for
bceT
DNA sequences were developed. The results from the amplification of
hblA
sequences correlated well with results obtained with the
B. cereus
enterotoxin (diarrheal type) test kit (RPLA kit), but not with the results of the
Bacillus
diarrheal enterotoxin visual immunoassay (BDE kit). Except for two thermophilic strains, all strains that were positive in PCR amplification assays with the
hblA
primers were also positive when tested with the RPLA kit. The
hblA
DNA sequence was found in 33 strains, and these strains were closely related according to 16S rDNA-RFLP analysis, except
B. pasteurii
. In PCR amplifications with the
bceT
primers only the model strain gave a positive signal. It is concluded that screening of the hemolysin HblA complex by the PCR method allows faster detection of enterotoxin production than does testing with the RPLA enterotoxin kit.
A Transposable Partitioning Locus Used To Stabilize Plasmid-Borne Hydrogen Oxidation and Trifolitoxin Production Genes in a
Sinorhizobium
Strain
Authors: Kent Angela D. , Wojtasiak Michelle L. , Robleto Eduardo A. , Triplett Eric W. 
Published: December 2019

ABSTRACT

Improved nitrogen-fixing inoculum strains for leguminous crops must be able to effectively compete with indigenous strains for nodulation, enhance legume productivity compared to the productivity obtained with indigenous strains, and maintain stable expression of any added genes in the absence of selection pressure. We constructed a transposable element containing the
tfx
region for expression of increased nodulation competitiveness and the
par
locus for plasmid stability. The transposon was inserted into
tetA
of pHU52, a broad-host-range plasmid conferring the H
2
uptake phenotype. The resulting plasmid, pHUTFXPAR, conferred the plasmid stability, trifolitoxin production, and H
2
uptake phenotypes in the broad-host-range organism
Sinorhizobium
sp. strain ANU280. The broad applications of a transposon conferring plasmid stability are discussed.
A Flow Cytometric Method for Rapid Selection of Novel Industrial Yeast Hybrids
Authors: Bell P. J. L. , Deere D. , Shen J. , Chapman B. , Bissinger P. H. , Attfield P. V. , Veal D. A. 
Published: December 2019

ABSTRACT

We rapidly produced and isolated novel yeast hybrids by using two-color flow cytometric cell sorting. We labeled one parent strain with a fluorescent green stain and the other parent with a fluorescent orange stain, and hybrids were selected based on their dual orange and green fluorescence. When this technique was applied to the production of hybrids by traditional mating procedures, more than 96% of the isolates were hybrids. When it was applied to rare mating, three hybrids were identified among 50 isolates enriched from a population containing 2 × 10
6
cells. This technology is not dependent on genetic markers and has applications in the development of improved industrial yeast strains.
Improved Isolation of
Vibrio vulnificus
from Seawater and Sediment with Cellobiose-Colistin Agar
Authors: Høi Lise , Dalsgaard Inger , Dalsgaard Anders 
Published: December 2019

ABSTRACT

An improved selective medium, cellobiose-colistin (CC) agar, gave a significantly higher (
P
< 0.05) isolation rate of
Vibrio vulnificus
from water and sediment samples than did modified cellobiose-polymyxin B-colistin (mCPC) agar. In a total of 446 alkaline peptone water preenrichments amended with polymyxin B,
V. vulnificus
was isolated from 154 preenrichments (35%) with mCPC agar and from 179 preenrichments (40%) with CC agar. CC agar gave a higher plating efficiency of
V. vulnificus
cells than did cellobiose-polymyxin B-colistin (CPC) agar, mCPC agar, or thiosulfate-citrate-bile salts-sucrose (TCBS) agar; the only significant difference was observed with TCBS agar, which gave much lower plating efficiencies than the other selective media. Determination of MICs demonstrated that the concentrations of colistin and polymyxin B in CPC agar inhibit growth of a proportion of
V. vulnificus
strains.
Cloning of the
xynB
Gene from
Dictyoglomus thermophilum
Rt46B.1 and Action of the Gene Product on Kraft Pulp
Authors: Morris Daniel D. , Gibbs Moreland D. , Chin Charles W. J. , Koh Mei-Hsien , Wong Ken K. Y. , Allison Robert W. , Nelson Peter J. , Bergquist Peter L. 
Published: December 2019

ABSTRACT

A two-step PCR protocol was used to identify and sequence a family 11 xylanase gene from
Dictyoglomus thermophilum
Rt46B.1. Family 11 xylanase consensus fragments (GXCFs) were amplified from Rt46B.1 genomic DNA by using different sets of consensus PCR primers that exhibited broad specificity for conserved motifs within fungal and/or bacterial family 11 xylanase genes. On the basis of the sequences of a representative sample of the GXCFs a single family 11 xylanase gene (
xynB
) was identified. The entire gene sequence was obtained in the second step by using genomic walking PCR to amplify Rt46B.1 genomic DNA fragments upstream and downstream of the
xynB
GXCF region. The putative XynB peptide (
M
r
, 39,800) encoded by the Rt46B.1
xynB
open reading frame was a multidomain enzyme comprising an N-terminal catalytic domain (
M
r
, 22,000) and a possible C-terminal substrate-binding domain (
M
r
, 13,000) that were separated by a short serine-glycine-rich 23-amino-acid linker peptide. Seven xylanases which differed at their N and C termini were produced from different
xynB
expression plasmids. All seven xylanases exhibited optimum activity at pH 6.5. However, the temperature optima of the XynB xylanases varied from 70 to 85°C. Pretreatment of
Pinus radiata
and eucalypt kraft-oxygen pulps with XynB resulted in moderate xylan solubilization and a substantial improvement in the bleachability of these pulps.
Ammonia-Hyperproducing Bacteria from New Zealand Ruminants
Authors: Attwood Graeme T. , Klieve Athol V. , Ouwerkerk Diane , Patel Bharat K. C. 
Published: December 2019

ABSTRACT

Pasture-grazed dairy cows, deer, and sheep were tested for the presence of ammonia-hyperproducing (HAP) bacteria in roll tubes containing a medium in which tryptone and Casamino Acids were the sole nitrogen and energy sources. Colonies able to grow on this medium represented 5.2, 1.3, and 11.6% of the total bacterial counts of dairy cows, deer, and sheep, respectively. A total of 14 morphologically distinct colonies were purified and studied further. Restriction fragment length polymorphisms of 16S rRNA genes indicated that all isolates differed from the previously described HAP bacteria,
Clostridium aminophilum
,
Clostridium sticklandii
, and
Peptostreptococcus anaerobius
. Carbon source utilization experiments showed that five isolates (C2, D1, D4, D5, and S1) were unable to use any, or very few, of the carbon sources tested. Biochemical tests and phylogenetic analyses of 16S ribosomal DNA sequences indicated that all isolates were monensin sensitive; that D1 and S1 belonged to the genus
Peptostreptococcus
, that D4 and D5 belonged to the family
Bacteroidaceae
, where D4 was similar to
Fusobacterium necrophorum
; and that C2 was most similar to an unidentified species from the genus
Eubacterium
. Growth on liquid medium containing tryptone and Casamino Acids as the sole nitrogen and energy source showed that D1, D4, and S1 grew rapidly (specific growth rates of 0.40, 0.35, and 0.29 h
−1
, respectively), while C2 and D5 were slow growers (0.25 and 0.10 h
−1
, respectively). Ammonia production rates were highest in D1 and D4, which produced 945.5 and 748.3 nmol/min per mg of protein, respectively. Tests of individual nitrogen sources indicated that D1 and D4 grew best on tryptone, S1 grew equally well on Casamino Acids or tryptone, and C2 and D5 grew poorly on all nitrogen sources. The intact proteins casein and gelatin did not support significant growth of any of the isolates. These isolates extend the diversity of known HAP rumen bacteria and indicate the presence of significant HAP bacterial populations in pasture-grazed New Zealand ruminants.
Maximizing Plasmid Stability and Production of Released Proteins in
Yersinia enterocolitica
Authors: Li Huaiyu , Bhaduri Saumya , Magee Wayne E. 
Published: December 2019

ABSTRACT

Virulent serotypes of
Yersinia enterocolitica
carry a plasmid (pYV) encoding a family of proteins that are released into the medium and whose expression is temperature and calcium regulated. The plasmid is easily lost from cells during their growth in the laboratory. We have used sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting with a monoclonal antibody (3.2C) that is specific for a 25-kDa released protein to show that 32°C is the lowest temperature at which plasmid-encoded proteins are expressed in quantity. The highest calcium concentration allowing full expression of these proteins was 445 to 545 μM at 32°C. Calcium concentrations of 745 μM and above at 37°C completely prevented the loss of pYV during multiple subcultures, while at 32°C, calcium concentrations of 245 μM and greater were sufficient to stabilize the plasmid. Growth of
Y. enterocolitica
at pH 5.5 was slower than at neutral pH values, but it also resulted in greatly increased stability of pYV. These studies showed that bacterial growth, retention of pYV, and expression of plasmid-encoded proteins may be maximized at 32°C with 445 μM calcium and that pYV stability is enhanced by growth at low pH. These observations suggest new approaches for isolation of plasmid-bearing virulent strains of
Y. enterocolitica
from samples contaminated with this organism and also may improve our understanding of pYV retention in vivo.