bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antimicrobial Resistance of Staphylococcus aureus Strains Acquired by Pig Farmers from Pigs
Authors: Oppliger Anne , Moreillon Philippe , Charrière Nicole , Giddey Marlyse , Morisset Delphine , Sakwinska Olga 
Published: September 2012

ABSTRACT

Carriage of animal-associated methicillin-resistant
Staphylococcus aureus
(MRSA) clonal complex 398 (CC398) is common among pig farmers. This study was conducted (i) to investigate whether pig farmers are colonized with pig-specific
S. aureus
genotypes other than CC398 and (ii) to survey antimicrobial resistance of
S. aureus
isolates from pigs and pig farmers. Forty-eight
S. aureus
isolates from pig farmers and veterinarians and 130 isolates from pigs collected in Western Switzerland were genotyped by
spa
typing and amplified fragment length polymorphism (AFLP). Antimicrobial resistance profiles were determined for representative sample of the isolates. The data obtained earlier on healthy
S. aureus
carriers without exposure to agriculture were used for comparison. The genotype composition of
S. aureus
isolates from pig farmers and veterinarians was similar to isolates from pigs with predominant AFLP clusters CC398, CC9, and CC49. The resistance to tetracycline and macrolides (clarithromycin) was common among the isolates from farmers and veterinarians (52 and 21%, respectively) and similar to resistance levels in isolates from pigs (39 and 23%, respectively). This was in contrast to isolates from persons without contact with agriculture, where no (0/128) isolates were resistant to tetracycline and 3% of the isolates were resistant to clarithromycin. MRSA CC398 was isolated from pigs (
n
= 11) and pig farmers (
n
= 5). These data imply that zoonotic transmission of multidrug-resistant
S. aureus
from pigs to farmers is frequent, and well-known MRSA transmission merely represents the tip of the iceberg for this phenomenon. We speculate that the relatively low frequency of MRSA isolation is related to lower antimicrobial use in Switzerland compared to, for example, the Netherlands.
High Prevalence and Species Diversity of Helicobacter spp. Detected in Wild House Mice
Authors: Wasimuddin  , Čížková Dagmar , Bryja Josef , Albrechtová Jana , Hauffe Heidi C. , Piálek Jaroslav 
Published: September 2012

ABSTRACT

PCR diagnostics detected 100% prevalence of
Helicobacter
in 425 wild house mice (
Mus musculus
) from across central Europe. Of seven species identified, the five most frequent were
Helicobacter rodentium
(78%),
H. typhlonius
(53%),
H. hepaticus
(41%),
H. bilis
(30%), and
H. muridarum
(1%). Double infections were more common (42%) than single (30%) and triple (21%) infections. Wild house mice could be considered potential reservoirs of
Helicobacter
strains for both humans and other vertebrates.
Intestinal Bacterium Eubacterium cellulosolvens Deglycosylates Flavonoid
C-
and
O-
Glucosides
Authors: Braune Annett , Blaut Michael 
Published: September 2012

ABSTRACT

Eubacterium cellulosolvens
cleaved the flavone
C
-glucosides homoorientin and isovitexin to their aglycones luteolin and apigenin, respectively. The corresponding isomers, orientin and vitexin, or other polyphenolic
C
-glucosides were not deglycosylated.
E. cellulosolvens
also cleaved several
O
-coupled glucosides of flavones and isoflavones to their corresponding aglycones.
Different Roles for Lactococcal Aggregation Factor and Mucin Binding Protein in Adhesion to Gastrointestinal Mucosa
Authors: Lukić Jovanka , Strahinić Ivana , Jovčić Branko , Filipić Brankica , Topisirović Ljubiša , Kojić Milan , Begović Jelena 
Published: September 2012

ABSTRACT

Adhesion of bacteria to mucosal surfaces and epithelial cells is one of the key features for the selection of probiotics. In this study, we assessed the adhesion property of
Lactococcus lactis
subsp.
lactis
BGKP1 based on its strong autoaggregation phenotype and the presence of the mucin binding protein (MbpL). Genes involved in aggregation (
aggL
) and possible interaction with mucin (
mbpL
), present on the same plasmid pKP1, were previously separately cloned in the plasmid pAZIL.
In vivo
and
in vitro
experiments revealed potentially different physiological roles of these two proteins in the process of adherence to the intestine during the passage of the strain through the gastrointestinal tract. We correlated the
in vitro
and
in vivo
aggregation of the BGKP1-20 carrying plasmid with
aggL
to binding to the colonic mucus through nonspecific hydrophobic interactions. The expression of AggL on the bacterial cell surface significantly increased the hydrophobicity of the strain. On the other hand, the presence of AggL in the strain reduced its ability to adhere to the ileum. Moreover, MbpL protein showed an affinity to bind gastric type mucin proteins such as MUC5AC. This protein did not contribute to the binding of the strain to the ileal or colonic part of the intestine. Different potential functions of lactococcal AggL and MbpL proteins in the process of adhesion to the gastrointestinal tract are proposed.
Pleiotropic Control of Secondary Metabolism and Morphological Development by KsbC, a Butyrolactone Autoregulator Receptor Homologue in Kitasatospora setae
Authors: Aroonsri Aiyada , Kitani Shigeru , Hashimoto Junko , Kosone Ikuko , Izumikawa Miho , Komatsu Mamoru , Fujita Nobuyuki , Takahashi Yoko , Shin-ya Kazuo , Ikeda Haruo , Nihira Takuya 
Published: September 2012

ABSTRACT

The γ-butyrolactone autoregulator signaling cascades have been shown to control secondary metabolism and/or morphological development among many
Streptomyces
species. However, the conservation and variation of the regulatory systems among actinomycetes remain to be clarified. The genome sequence of
Kitasatospora setae
, which also belongs to the family
Streptomycetaceae
containing the genus
Streptomyces
, has revealed the presence of three homologues of the autoregulator receptor: KsbA, which has previously been confirmed to be involved only in secondary metabolism; KsbB; and KsbC. We describe here the characterization of
ksbC
, whose regulatory cluster closely resembles the
Streptomyces virginiae barA
locus responsible for the autoregulator signaling cascade. Deletion of the gene
ksbC
resulted in lowered production of bafilomycin and a defect of aerial mycelium formation, together with the early and enhanced production of a novel β-carboline alkaloid named kitasetaline. A putative kitasetaline biosynthetic gene cluster was identified, and its expression in a heterologous host led to the production of kitasetaline together with JBIR-133, the production of which is also detected in the
ksbC
disruptant, and JBIR-134 as novel β-carboline alkaloids, indicating that these genes were biosynthetic genes for β-carboline alkaloid and thus are the first such genes to be discovered in bacteria.
Differences in Colonization and Shedding Patterns after Oral Challenge of Cattle with Three Escherichia coli O157:H7 Strains
Authors: Kulow Megan J. , Gonzales Tina K. , Pertzborn Kelly M. , Dahm James , Miller Bret A. , Park Dongjin , Gautam Raju , Kaspar Charles W. , Ivanek Renata , Döpfer Dörte 
Published: September 2012

ABSTRACTExperimental oral challenge studies with three different genotypes ofEscherichia coliO157:H7 were conducted in cattle to determine the genotype-specific variability in shedding frequencies and concentrations and the frequency and extent of contamination of the environment. The results indicated that theE. coliO157:H7 genotype and ecological origin maybe important factors for the occurrence and concentration in the cattle host. Four groups of six young Holstein steers each were orally challenged with 106CFU of one of threeE. coliO157:H7 strains: FRIK 47 (groups 1 and 2), FRIK 1641 (group 3), and FRIK 2533 (group 4). Recto-anal mucosal swabs (RAMS) and environmental samples were taken on alternate days over 30 days. The numbers ofE. coliO157:H7 cells and genericE. colicells per sample were determined. Also, the presence and absence of 28 gene targets were determined for 2,411 isolates using high-throughput real-time PCR. Over the study period, strains FRIK 47, FRIK 1641, and FRIK 2533 were detected in 52%, 42%, and 2% of RAMS, respectively. Environmental detection of the challenge strains was found mainly in samples of the hides and pen floors, with strains FRIK 47, FRIK 1641, and FRIK 2533 detected in 22%, 27%, and 0% of environmental samples, respectively. Based on the panel of 28 gene targets, genotypes of enterohemorrhagicE. coli(EHEC) and genericE. colifrom the experimental samples were clustered into three subgroups. In conclusion, the results suggested that the type and intensity of measures to control this pathogen at the preharvest level may need to be strain specific.
Physiological Significance of Network Organization in Fungi
Authors: Simonin Anna , Palma-Guerrero Javier , Fricker Mark , Glass N. Louise 
Published: September 2012

ABSTRACT

The evolution of multicellularity has occurred in diverse lineages and in multiple ways among eukaryotic species. For plants and fungi, multicellular forms are derived from ancestors that failed to separate following cell division, thus retaining cytoplasmic continuity between the daughter cells. In networked organisms, such as filamentous fungi, cytoplasmic continuity facilitates the long-distance transport of resources without the elaboration of a separate vascular system. Nutrient translocation in fungi is essential for nutrient cycling in ecosystems, mycorrhizal symbioses, virulence, and substrate utilization. It has been proposed that an interconnected mycelial network influences resource translocation, but the theory has not been empirically tested. Here we show, by using mutants that disrupt network formation in
Neurospora crassa
(Δ
so
mutant, no fusion; Δ
Prm-1
mutant, ∼50% fusion), that the translocation of labeled nutrients is adversely affected in homogeneous environments and is even more severely impacted in heterogeneous environments. We also show that the ability to share resources and genetic exchange between colonies (via hyphal fusion) is very limited in mature colonies, in contrast to in young colonies and germlings that readily share nutrients and genetic resources. The differences in genetic/resource sharing between young and mature colonies were associated with variations in colony architecture (hyphal differentiation/diameters, branching patterns, and angles). Thus, the ability to share resources and genetic material between colonies is developmentally regulated and is a function of the age of a colony. This study highlights the necessity of hyphal fusion for efficient nutrient translocation within an
N. crassa
colony but also shows that established
N. crassa
colonies do not share resources in a significant manner.
Insights into Glycogen Metabolism in Chemolithoautotrophic Bacteria from Distinctive Kinetic and Regulatory Properties of ADP-Glucose Pyrophosphorylase from Nitrosomonas europaea
Authors: Machtey Matías , Kuhn Misty L. , Flasch Diane A. , Aleanzi Mabel , Ballicora Miguel A. , Iglesias Alberto A. 
Published: September 2012

ABSTRACTNitrosomonas europaeais a chemolithoautotroph that obtains energy by oxidizing ammonia in the presence of oxygen and fixes CO2via the Benson-Calvin cycle. Despite its environmental and evolutionary importance, very little is known about the regulation and metabolism of glycogen, a source of carbon and energy storage. Here, we cloned and heterologously expressed the genes coding for two major putative enzymes of the glycogen synthetic pathway inN. europaea, ADP-glucose pyrophosphorylase and glycogen synthase. In other bacteria, ADP-glucose pyrophosphorylase catalyzes the regulatory step of the synthetic pathway and glycogen synthase elongates the polymer. In starch synthesis in plants, homologous enzymes play similar roles. We purified to homogeneity the recombinant ADP-glucose pyrophosphorylase fromN. europaeaand characterized its kinetic, regulatory, and oligomeric properties. The enzyme was allosterically activated by pyruvate, oxaloacetate, and phosphoenolpyruvate and inhibited by AMP. It had a broad thermal and pH stability and used different divalent metal ions as cofactors. Depending on the cofactor, the enzyme was able to accept different nucleotides and sugar phosphates as alternative substrates. However, characterization of the recombinant glycogen synthase showed that only ADP-Glc elongates the polysaccharide, indicating that ATP and glucose-1-phosphate are the physiological substrates of the ADP-glucose pyrophosphorylase. The distinctive properties with respect to selectivity for substrates and activators of the ADP-glucose pyrophosphorylase were in good agreement with the metabolic routes operating inN. europaea, indicating an evolutionary adaptation. These unique properties place the enzyme in a category of its own within the family, highlighting the unique regulation in these organisms.
A Novel Component of the Rhodobacter sphaeroides Fla1 Flagellum Is Essential for Motor Rotation
Authors: Ramírez-Cabrera Victor , Poggio Sebastian , Domenzain Clelia , Osorio Aurora , Dreyfus Georges , Camarena Laura 
Published: September 2012

ABSTRACT

Here we describe a novel component essential for flagellar rotation in
Rhodobacter sphaeroides
. This protein is encoded by
motF
(RSP_0067), the first gene of a predicted transcriptional unit which contains two hypothetical genes. Sequence analysis indicated that MotF is a bitopic membrane-spanning protein. Protease sensitivity assays and green fluorescent protein (GFP) fusions confirmed this prediction and allowed us to conclude that the C terminus of MotF is located in the periplasmic space. Wild-type cells expressing a functional GFP-MotF fusion show a single fluorescent focus per cell. The localization of this protein in different genetic backgrounds allowed us to determine that normal localization of MotF depends on the presence of FliL and MotB. Characterization of a Δ
motF
pseudorevertant strain revealed that a single nucleotide change in
motB
suppresses the Mot
−
phenotype of the
motF
mutant. Additionally, we show that MotF also becomes dispensable when other mutant alleles of
motB
previously isolated as second-site suppressors of Δ
fliL
were expressed in the
motF
mutant strain. These results show that MotF is a new component of the Fla1 flagellum, which together with FliL is required to promote flagellar rotation, possibly through MotB.
The Lysozyme-Induced Peptidoglycan
N
-Acetylglucosamine Deacetylase PgdA (EF1843) Is Required for Enterococcus faecalis Virulence
Authors: Benachour Abdellah , Ladjouzi Rabia , Le Jeune André , Hébert Laurent , Thorpe Simon , Courtin Pascal , Chapot-Chartier Marie-Pierre , Prajsnar Tomasz K. , Foster Simon J. , Mesnage Stéphane 
Published: September 2012

ABSTRACT

Lysozyme is a key component of the innate immune response in humans that provides a first line of defense against microbes. The bactericidal effect of lysozyme relies both on the cell wall lytic activity of this enzyme and on a cationic antimicrobial peptide activity that leads to membrane permeabilization. Among Gram-positive bacteria, the opportunistic pathogen
Enterococcus faecalis
has been shown to be extremely resistant to lysozyme. This unusual resistance is explained partly by peptidoglycan
O
-acetylation, which inhibits the enzymatic activity of lysozyme, and partly by
d
-alanylation of teichoic acids, which is likely to inhibit binding of lysozyme to the bacterial cell wall. Surprisingly, combined mutations abolishing both peptidoglycan
O
-acetylation and teichoic acid alanylation are not sufficient to confer lysozyme susceptibility. In this work, we identify another mechanism involved in
E. faecalis
lysozyme resistance. We show that exposure to lysozyme triggers the expression of EF1843, a protein that is not detected under normal growth conditions. Analysis of peptidoglycan structure from strains with
EF1843
loss- and gain-of-function mutations, together with
in vitro
assays using recombinant protein, showed that EF1843 is a peptidoglycan
N
-acetylglucosamine deacetylase. EF1843-mediated peptidoglycan deacetylation was shown to contribute to lysozyme resistance by inhibiting both lysozyme enzymatic activity and, to a lesser extent, lysozyme cationic antimicrobial activity. Finally,
EF1843
mutation was shown to reduce the ability of
E. faecalis
to cause lethality in the
Galleria mellonella
infection model. Taken together, our results reveal that peptidoglycan deacetylation is a component of the arsenal that enables
E. faecalis
to thrive inside mammalian hosts, as both a commensal and a pathogen.
Alternative Excision Repair of Ultraviolet B- and C-Induced DNA Damage in Dormant and Developing Spores of Bacillus subtilis
Authors: Ramírez-Guadiana Fernando H. , Barraza-Salas Marcelo , Ramírez-Ramírez Norma , Ortiz-Cortés Mayte , Setlow Peter , Pedraza-Reyes Mario 
Published: September 2012

ABSTRACT

The nucleotide excision repair (NER) and spore photoproduct lyase DNA repair pathways are major determinants of
Bacillus subtilis
spore resistance to UV radiation. We report here that a putative ultraviolet (UV) damage endonuclease encoded by
ywjD
confers protection to developing and dormant spores of
B. subtilis
against UV DNA damage. In agreement with its predicted function, a His
6
-YwjD recombinant protein catalyzed the specific incision of UV-irradiated DNA
in vitro
. The maximum expression of a reporter gene fusion to the
ywjD
opening reading frame occurred late in sporulation, and this maximal expression was dependent on the forespore-specific RNA polymerase sigma factor, σ
G
. Although the absence of YwjD and/or UvrA, an essential protein of the NER pathway, sensitized developing spores to UV-C, this effect was lower when these cells were treated with UV-B. In contrast, UV-B but not UV-C radiation dramatically decreased the survival of dormant spores deficient in both YwjD and UvrA. The distinct range of lesions generated by UV-C and UV-B and the different DNA photochemistry in developing and dormant spores may cause these differences. We postulate that in addition to the UvrABC repair system, developing and dormant spores of
B. subtilis
also rely on an alternative excision repair pathway involving YwjD to deal with the deleterious effects of various UV photoproducts.
Identification and Characterization of Five Intramembrane Metalloproteases in Anabaena variabilis
Authors: Chen Kangming , Gu Liping , Xiang Xianling , Lynch Michael , Zhou Ruanbao 
Published: September 2012

ABSTRACT

Regulated intramembrane proteolysis (RIP) involves cleavage of a transmembrane segment of a protein, releasing the active form of a membrane-anchored transcription factor (MTF) or a membrane-tethered signaling protein in response to an extracellular or intracellular signal. RIP is conserved from bacteria to humans and governs many important signaling pathways in both prokaryotes and eukaryotes. Proteases that carry out these cleavages are named intramembrane cleaving proteases (I-CLips). To date, little is known about I-CLips in cyanobacteria. In this study, five putative site-2 type I-Clips (Ava_1070, Ava_1730, Ava_1797, Ava_3438, and Ava_4785) were identified through a genome-wide survey in
Anabaena variabilis
. Biochemical analysis demonstrated that these five putative
A. variabilis
site-2 proteases (S2Ps

Av

) have authentic protease activities toward an artificial substrate pro-σ
K
, a
Bacillus subtilis
MTF, in our reconstituted
Escherichia coli
system. The enzymatic activities of processing pro-σ
K
differ among these five S2Ps

Av

. Substitution of glutamic acid (E) by glutamine (Q) in the conserved HEXXH zinc-coordinated motif caused the loss of protease activities in these five S2Ps

Av

, suggesting that they belonged to the metalloprotease family. Further mapping of the cleaved peptides of pro-σ
K
by Ava_4785 and Ava_1797 revealed that Ava_4785 and Ava_1797 recognized the same cleavage site in pro-σ
K
as SpoIVFB, a cognate S2P of pro-σ
K
from
B. subtilis
. Taking these results together, we report here for the first time the identification of five metallo-intramembrane cleaving proteases in
Anabaena variabilis
. The experimental system described herein should be applicable to studies of other RIP events and amenable to developing
in vitro
assays for I-CLips.
Hyperosmotic Stress Response of Campylobacter jejuni
Authors: Cameron Andrew , Frirdich Emilisa , Huynh Steven , Parker Craig T. , Gaynor Erin C. 
Published: September 2012

ABSTRACT

The diarrheal pathogen
Campylobacter jejuni
and other gastrointestinal bacteria encounter changes in osmolarity in the environment, through exposure to food processing, and upon entering host organisms, where osmotic adaptation can be associated with virulence. In this study, growth profiles, transcriptomics, and phenotypic, mutant, and single-cell analyses were used to explore the effects of hyperosmotic stress exposure on
C. jejuni
. Increased growth inhibition correlated with increased osmotic concentration, with both ionic and nonionic stressors inhibiting growth at 0.620 total osmol liter
−1
.
C. jejuni
adaptation to a range of osmotic stressors and concentrations was accompanied by severe filamentation in subpopulations, with microscopy indicating septum formation and phenotypic diversity between individual cells in a filament. Population heterogeneity was also exemplified by the bifurcation of colony morphology into small and large variants on salt stress plates. Flow cytometry of
C. jejuni
harboring green fluorescent protein (GFP) fused to the ATP synthase promoter likewise revealed bimodal subpopulations under hyperosmotic stress. We also identified frequent hyperosmotic stress-sensitive variants within the clonal wild-type population propagated on standard laboratory medium. Microarray analysis following hyperosmotic upshift revealed enhanced expression of heat shock genes and genes encoding enzymes for synthesis of potential osmoprotectants and cross-protective induction of oxidative stress genes. The capsule export gene
kpsM
was also upregulated, and an acapsular mutant was defective for growth under hyperosmotic stress. For
C. jejuni
, an organism lacking most conventional osmotic response factors, these data suggest an unusual hyperosmotic stress response, including likely “bet-hedging” survival strategies relying on the presence of stress-fit individuals in a heterogeneous population.
SurA Is Involved in the Targeting to the Outer Membrane of a Tat Signal Sequence-Anchored Protein
Authors: Rondelet Arnaud , Condemine Guy 
Published: September 2012

ABSTRACT

The twin arginine translocation (Tat) pathway exports folded proteins from the cytoplasm to the periplasm of bacteria. The targeting of the exported proteins to the Tat pathway relies on a specific amino-terminal signal sequence, which is cleaved after exportation. In the phytopathogen
Dickeya dadantii
, the pectin lyase homologue PnlH is exported by the Tat pathway without cleavage of its signal sequence, which anchors PnlH into the outer membrane. In proteobacteria, the vast majority of outer membrane proteins consists of β-barrel proteins and lipoproteins. Thus, PnlH represents a new kind of outer membrane protein. In
Escherichia coli
, periplasmic chaperones SurA, Skp, and DegP work together with the β-barrel assembly machinery (Bam) to target and insert β-barrel proteins into the outer membrane. In this work, we showed that SurA is required for an efficient targeting of PnlH to the outer membrane. Moreover, we were able to detect an
in vitro
interaction between SurA and the PnlH signal sequence. Since the PnlH signal sequence contains a highly hydrophobic region, we propose that SurA protects it from the hydrophobic periplasm during targeting of PnlH to the outer membrane. We also studied the nature of the information carried by the PnlH signal sequence responsible for its targeting to the outer membrane after exportation by the Tat system.