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phosphorothioate dna as an antioxidant in bacteria.diverse bacteria contain dna with sulfur incorporated stereo-specifically into their dna backbone at specific sequences (phosphorothioation). we found that in vitro oxidation of phosphorothioate (pt) dna by hydrogen peroxide (h(2)o(2)) or peracetic acid has two possible outcomes: dna backbone cleavage or sulfur removal resulting in restoration of normal dna backbone. the physiological relevance of this redox reaction was investigated by challenging pt dna hosting salmonella enterica cells using ...201222772986
evaluation of near-infrared pasteurization in controlling escherichia coli o157:h7, salmonella enterica serovar typhimurium, and listeria monocytogenes in ready-to-eat sliced ham.this study was conducted to investigate the efficacy of near-infrared (nir) heating to reduce salmonella enterica serovar typhimurium, escherichia coli o157:h7, and listeria monocytogenes in ready-to-eat (rte) sliced ham compared to conventional convective heating, and the effect of nir heating on quality was determined by measuring the color and texture change. a cocktail of three pathogens was inoculated on the exposed or protected surfaces of ham slices, followed by nir or conventional heatin ...201222773635
significance of the bacteriophage treatment schedule in reducing salmonella colonization of poultry.salmonella remains the major cause of food-borne diseases worldwide, with chickens known to be the main reservoir for this zoonotic pathogen. among the many approaches to reducing salmonella colonization of broilers, bacteriophage offers several advantages. in this study, three bacteriophages (uab_phi20, uab_phi78, and uab_phi87) obtained from our collection that exhibited a broad host range against salmonella enterica serovar enteritidis and salmonella enterica serovar typhimurium were characte ...201222773654
functional analysis of bacillus subtilis genes involved in the biosynthesis of 4-thiouridine in trna.thii has been identified as an essential enzyme involved in the biosynthesis of thiamine and the trna thionucleoside modification, 4-thiouridine. in escherichia coli and salmonella enterica, thii acts as a sulfurtransferase, receiving the sulfur donated from the cysteine desulfurase iscs and transferring it to the target molecule or additional sulfur carrier proteins. however, in bacillus subtilis and most species from the firmicutes phylum, thii lacks the rhodanese domain that contains the site ...201222773787
enhancement of th1-biased protective immunity against avian influenza h9n2 virus via oral co-administration of attenuated salmonella enterica serovar typhimurium expressing chicken interferon-α and interleukin-18 along with an inactivated vaccine.control of currently circulating re-assorted low-pathogenicity avian influenza (lpai) h9n2 is a major concern for both animal and human health. thus, an improved lpai h9n2 vaccination strategy is needed to induce complete immunity in chickens against lpai h9n2 virus strains. cytokines play a crucial role in mounting both the type and extent of an immune response generated following infection with a pathogen or after vaccination. to improve the efficacy of inactivated lpai h9n2 vaccine, attenuate ...201222776696
a whole-cell phenotypic screening platform for identifying methylerythritol phosphate pathway-selective inhibitors as novel antibacterial agents.isoprenoid biosynthesis is essential for survival of all living organisms. more than 50,000 unique isoprenoids occur naturally, with each constructed from two simple five-carbon precursors: isopentenyl diphosphate (ipp) and dimethylallyl diphosphate (dmapp). two pathways for the biosynthesis of ipp and dmapp are found in nature. humans exclusively use the mevalonate (mva) pathway, while most bacteria, including all gram-negative and many gram-positive species, use the unrelated methylerythritol ...201222777049
fima, fimf, and fimh are necessary for assembly of type 1 fimbriae on salmonella enterica serovar typhimurium.salmonella enterica serovar typhimurium is a gram-negative member of the family enterobacteriaceae and is a common cause of bacterial food poisoning in humans. the fimbrial appendages are found on the surface of many enteric bacteria and enable the bacteria to bind to eukaryotic cells. s. typhimurium type 1 fimbriae are characterized by mannose-sensitive hemagglutination and are assembled via the chaperone/usher pathway. s. typhimurium type 1 fimbrial proteins are encoded by the fim gene cluster ...201222778099
diarrhea and colitis in mice require the salmonella pathogenicity island 2-encoded secretion function but not sifa or spv effectors.we investigated the roles of salmonella pathogenicity island 2 (spi-2) and two spi-2 effectors in salmonella colitis and diarrhea in genetically resistant balb/c.d2(slc11a1) congenic mice with the wild-type nramp1 locus. wild-type salmonella enterica serovar typhimurium 14028s caused a pan-colitis, and the infected mice developed frank diarrhea with a doubling of the fecal water content. an ssav mutant caused only a 26% increase in fecal water content, without producing the pathological changes ...201222778101
panm, an acetyl-coenzyme a sensor required for maturation of l-aspartate decarboxylase (pand).coenzyme a (coa) is essential for cellular chemistry in all forms of life. the pantothenate moiety of coa is generated from the condensation of pantoate and β-alanine. β-alanine is formed by decarboxylation of l-aspartate catalyzed by pand, a pyruvoyl enzyme that is synthesized by the cell as an inactive precursor (pro-pand). maturation of pro-pand into pand occurs via a self-cleavage event at residue ser25, which forms the catalytic pyruvoyl moiety. we recently reported that salmonella enterica ...201222782525
diversity and biological activities of endophytic fungi of emblica officinalis, an ethnomedicinal plant of india.in the present study, an attempt to evaluate the antimicrobial and antioxidant activity of fungal endophytes inhabiting emblica officinalis has been made keeping in view the medicinal importance of the selected host plant in indian traditional practices. a total of four endophytic fungi belonging to phylum ascomycetes were isolated from different parts of the plant which were characterized morphologically and by using rdna-internal transcribed spacer. the most frequently isolated endophyte was p ...201222783128
antimicrobial and synergistic effects of silver nanoparticles synthesized using soil fungi of high altitudes of eastern himalaya.fifty three fungi isolated from soils of different microhabitats of eastern himalayan range (3,400~3,600 msl) were screened for mycosynthesis of silver nanaoparticles (agnps) and their efficacy as antimicrobials were assessed in combination with commonly used antibiotics. three isolates aspergillus terreus sp5, paecilomyces lilacinus sf1 and fusarium sp. mp5 identified based on morphological and 18s rrna gene sequences were found to synthesize agnps. these nanoparticles were characterized by vis ...201222783131
the campylobacter jejuni dps homologue is important for in vitro biofilm formation and cecal colonization of poultry and may serve as a protective antigen for vaccination.in this work, we investigated the campylobacter jejuni dps (dna binding protein from starved cells) gene for a role in biofilm formation and cecal colonization in poultry. in vitro biofilm formation assays were conducted with stationary-phase cells in cell culture plates under microaerophilic conditions. these studies demonstrated a significant (>50%) reduction in biofilm formation by the c. jejuni dps mutant compared to that by the wild-type strain. studies in poultry also demonstrated the impo ...201222787197
drug resistance in salmonella enterica serotype typhi isolated from chronic typhoid carriers. 201222789724
a single residue determines the cooperative binding property of a primosomal dna replication protein, prib, to single-stranded dna.prib is a primosomal protein required for re-initiation of replication in bacteria. we characterized and compared the dna-binding properties of prib from salmonella enterica serovar typhimurium lt2 (stprib) and escherichia coli (ecprib). only one residue of ecprib, v6, was different in stprib (replaced by a6). previous structural information revealed that this residue is located on the putative dimer-dimer interface of prib and is not involved in single-stranded dna (ssdna) binding. the cooperat ...201222790931
comparative genome analysis of the high pathogenicity salmonella typhimurium strain uk-1.salmonella enterica serovar typhimurium, a gram-negative facultative rod-shaped bacterium causing salmonellosis and foodborne disease, is one of the most common isolated salmonella serovars in both developed and developing nations. several s. typhimurium genomes have been completed and many more genome-sequencing projects are underway. comparative genome analysis of the multiple strains leads to a better understanding of the evolution of s. typhimurium and its pathogenesis. s. typhimurium strain ...201222792393
the in vivo extracellular life of facultative intracellular bacterial parasites: role in pathogenesis.classically labeled facultative intracellular pathogens are characterized by the ability to have an intracellular phase in the host, which is required for pathogenicity, while capable of extracellular growth in vitro. the ability of these bacteria to replicate in cell-free conditions is usually assessed by culture in artificial bacteriological media. however, the extracellular growth ability of these pathogens may also be expressed by a phase of extracellular infection in the natural setting of ...201322795971
caspase-1 activity is required to bypass macrophage apoptosis upon salmonella infection.here we report awp28, an activity-based probe that can be used to biochemically monitor caspase-1 activation in response to proinflammatory stimuli. using awp28, we show that apoptosis is triggered upon salmonella enterica var. typhimurium infection in primary mouse bone marrow macrophages lacking caspase-1. furthermore, we report that upon salmonella infection, inflammasome-mediated caspase-1 activity is required to bypass apoptosis in favor of proinflammatory pyroptotic cell death.201222797665
convergent molecular evolution of genomic cores in salmonella enterica and escherichia coli.one of the strongest signals of adaptive molecular evolution of proteins is the occurrence of convergent hot spot mutations: repeated changes in the same amino acid positions. we performed a comparative genome-wide analysis of mutation-driven evolution of core (omnipresent) genes in 17 strains of salmonella enterica subspecies i and 22 strains of escherichia coli. more than 20% of core genes in both salmonella and e. coli accumulated hot spot mutations, with a predominance of identical changes h ...201222797756
a new methodology for differentiation and typing of closely related salmonella enterica serovar heidelberg isolates.this study describe the use of a combination of two recently proposed typing approaches, multiple amplification of prophage locus typing (maplt) and multiple-locus variable-number tandem-repeat analysis (mlva) for subdividing within salmonella enterica serovar heidelberg (s. heidelberg). the combined typing method was compared with pulsed-field gel electrophoresis (pfge) by simpson's index of diversity (di). pfge was shown to have a di = 0.84 and was poor at differentiation of the predominant pt ...201222797864
characterization of osmotically induced filaments of salmonella enterica.salmonella enterica forms aseptate filaments with multiple nucleoids when cultured in hyperosmotic conditions. these osmotic-induced filaments are viable and form single colonies on agar plates even though they contain multiple genomes and have the potential to divide into multiple daughter cells. introducing filaments that are formed during osmotic stress into culture conditions without additional humectants results in the formation of septa and their division into individual cells, which could ...201222798362
salmonella enterica serovar enteritidis phage type 4 outbreak associated with eggs in a large prison, london 2009: an investigation using cohort and case/non-case study methodology.in september 2009, an outbreak of salmonella enterica serovar enteritidis affected 327 of 1419 inmates at a london prison. we applied a cohort design using aggregated data from the kitchen about portions of food distributed, aligned this with individual food histories from 124 cases (18 confirmed, 106 probable) and deduced the exposures of those remaining well. results showed that prisoners eating egg cress rolls were 26 times more likely to be ill [risk ratio 25.7, 95% confidence interval (ci) ...201322800644
numbers of salmonella recovered by sponge or low volume whole carcass rinse sampling of inoculated commercial turkey carcasses.processed turkey carcasses are sampled for salmonella via sponge sampling, whereas broilers are sampled via whole carcass rinses. because different sampling methods have been reported to produce different results, sponge sampling and whole carcass rinsing (wcr) were performed on turkey hen carcasses inoculated with a known amount of nalidixic acid-resistant salmonella enterica serovar enteritidis. five turkey hen carcasses were collected from the shackle line in a commercial processing plant in ...201222802199
early strains of multidrug-resistant salmonella enterica serovar kentucky sequence type 198 from southeast asia harbor salmonella genomic island 1-j variants with a novel insertion sequence.salmonella genomic island 1 (sgi1) is a 43-kb integrative mobilizable element that harbors a great diversity of multidrug resistance gene clusters described in numerous salmonella enterica serovars and also in proteus mirabilis. the majority of sgi1 variants contain an in104-derivative complex class 1 integron inserted between resolvase gene res and open reading frame (orf) s044 in sgi1. recently, the international spread of ciprofloxacin-resistant s. enterica serovar kentucky sequence type 198 ...201222802251
leuo is a global regulator of gene expression in salmonella enterica serovar typhimurium.we report the first investigation of the binding of the salmonella enterica leuo lysr-type transcription regulator to its genomic targets in vivo. chromatin-immunoprecipitation-on-chip identified 178 leuo binding sites on the chromosome of s. enterica serovar typhimurium strain sl1344. these sites were distributed across both the core and the horizontally acquired genome, and included housekeeping genes and genes known to contribute to virulence. sixty-eight leuo targets were co-bound by the glo ...201222804842
salmonella enterica serovar ohio septic arthritis and bone abscess in an immunocompetent patient: a case report.non-typhi salmonella species cause severe extra-intestinal focal infection after occult bacteremia. although the number of cases of non-typhi salmonellosis is increasing worldwide among patients with immunocompromising conditions such as human immunodeficiency virus infection, infection is uncommon in immunocompetent subjects. we report a case of septic arthritis and bone abscess due to a rare non-typhi salmonella organism that developed after a prolonged asymptomatic period.201222804866
the antimicrobial effects of propolis collected in different regions in the basque country (northern spain).the antimicrobial activity of 19 propolis extracts prepared in different solvents (ethanol and propylene glycol) (eep/pep), was evaluated against some bacterial and fungal isolates using the agar-well diffusion method. it was verified that all the samples tested showed antimicrobial activity, although results varied considerably between samples. results revealed that both types of propolis extracts showed highly sensitive antimicrobial action against gram-positive bacteria and fungi at a concent ...201122805915
thymus maroccanus essential oil, a membranotropic compound active on gram-negative bacteria and resistant isolates.the effects of thymus maroccanus essential oil (eo) on the integrity of the cell membranes and the permeability of the outer membrane (om) and inner membrane (im) of escherichia coli, enterobacter aerogenes and salmonella enterica typhimurium were investigated.201222809088
development of an improved selective and differential medium for isolation of salmonella spp.we describe an improved selective, differential, and cost-effective medium, xa medium, which contains d-arabinose, to facilitate the selective isolation of salmonella spp. the sensitivity and the specificity of xa medium were compared to those of xylose lysine desoxycholate agar (xld) using stock cultures and naturally contaminated food samples. xa medium and xld were evaluated with a total of 82 salmonella and 69 non-salmonella stock cultures. of 82 strains of salmonella spp. tested, 76 produce ...201222814469
spi-1 encoded genes of salmonella typhimurium influence differential polarization of porcine alveolar macrophages in vitro.within the last decade, macrophages have been shown to be capable of differentiating toward a classically activated phenotype (m1) with a high antimicrobial potential or an alternatively activated phenotype (m2). some pathogens are capable of interfering with differentiation in order to down-regulate the anti-microbial activity and enhance their survival in the host.201222817641
assessment of root uptake and systemic vine-transport of salmonella enterica sv. typhimurium by melon (cucumis melo) during field production.among melons, cantaloupes are most frequently implicated in outbreaks and surveillance-based recalls due to salmonella enterica. there is limited but compelling evidence that associates irrigation water quality as a significant risk of preharvest contamination of melons. however, the potential for root uptake from water and soil and subsequent systemic transport of salmonella into melon fruit is uncharacterized. the aim of this work was to determine whether root uptake of s. enterica results in ...201222824339
vaccines for typhoid fever and other salmonelloses.this review summarizes the recent advances in vaccination against salmonella enterica serovar typhi and highlights the data supporting the development of next generation vaccines to address paratyphoid fever and invasive nontyphoidal salmonella (ints) disease.201222825288
reduction in resident microflora, and experimentally inoculated salmonella enterica, on spinach leaves treated with vinegar and canola oil.in this study, we explored the use of vinegar, or vinegar and canola oil as a salad dressing, to reduce bacterial levels on spinach leaves. we found that incubation of spinach leaves with various types of vinegar substantially reduced the predominantly gram-negative microflora. a similar response was observed when spinach leaves were incubated with white vinegar mixed in various proportions with canola oil, as used in salad dressing. we assessed the effects of vinegar, or vinegar and oil, on spi ...201222828283
supported lipopolysaccharide bilayers.in this report, the formation of supported lipopolysaccharide bilayers (lps-slbs) is studied with extracted native and glycoengineered lps from escherichia coli ( e. coli ) and salmonella enterica sv typhimurium ( s. typhimurium ) to assemble a platform that allows measurement of lps membrane structure and the detection of membrane tethered saccharide-protein interactions. we present quartz crystal microbalance with dissipation monitoring (qcm-d) and fluorescence recovery after photobleaching (f ...201222830310
the nsrr regulon in nitrosative stress resistance of salmonella enterica serovar typhimurium.nitric oxide (no·) is an important mediator of innate immunity. the facultative intracellular pathogen salmonella has evolved mechanisms to detoxify and evade the antimicrobial actions of host-derived no· produced during infection. expression of the no·-detoxifying flavohaemoglobin hmp is controlled by the no·-sensing transcriptional repressor nsrr and is required for salmonella virulence. in this study we show that nsrr responds to very low no· concentrations, suggesting that it plays a primary ...201222831173
salmonella can reach tomato fruits on plants exposed to aerosols formed by rain.outbreaks of salmonella enterica have been associated with tomatoes and traced back to production areas but the spread of salmonella in agricultural fields is still poorly understood. post-rain salmonella transfer from a point source to the air and then to tomato plants was evaluated. gfp-labeled kanamycin-resistant s. enterica serovar typhimurium (10(8)cfu/ml) with and without expression of the rdar morphotype (rough colonies; cells with fimbriae and cellulose) was used as the point source in t ...201222831820
characterization of five novel endolysins from gram-negative infecting bacteriophages.we here characterize five globular endolysins, encoded by a set of gram-negative infecting bacteriophages: bcepc6gp22 (burkholderia cepacia phage bcepc6b), p2gp09 (escherichia coli phage p2), psp3gp10 (salmonella enterica phage psp3), k11gp3.5 and kp32gp15 (klebsiella pneumoniae phages k11 and kp32, respectively). in silico, bcepc6gp22, p2gp10 and psp3gp10 are predicted to possess lytic transglycosylase activity, whereas k11gp3.5 and kp32gp15 have putative amidase activity. all five endolysins s ...201322832988
epigenetic modification: possible approach to reduce salmonella enterica serovar enteritidis susceptibility under stress conditions.stressors may influence chicken susceptibility to pathogens such as salmonella enterica. feed withdrawal stress can cause changes in normal intestinal epithelial structure and may lead to increased attachment and colonization of salmonella. this study aimed to investigate modulatory effects of epigenetic modification by feed restriction on s. enterica serovar enteritidis colonization in broiler chickens subjected to feed withdrawal stress. chicks were divided into four groups: ad libitum feeding ...201222834548
zinc prevents salmonella enterica serovar typhimurium-induced loss of intestinal mucosal barrier function in broiler chickens.the study was carried out to evaluate the beneficial effects of supplemental zinc (zn) on the intestinal mucosal barrier function in salmonella enterica serovar typhimurium-challenged broiler chickens in a 42-day experiment. a total of 336 1-day-old male arbor acres broiler chicks were assigned to eight treatment groups. a 4×2 factorial arrangement of treatments was used in a completely randomized experimental design to study the effects of levels of supplemental zn (0, 40, 80 and 120 mg/kg diet ...201222834550
salmonella prevalence among reptiles in a zoo education setting.clinically healthy reptiles may shed salmonella and therefore act as a potential zoonotic threat. most people in northern european countries are rarely exposed to reptiles, but many zoos have education departments where children have direct contact with this group of animals. the objectives of this study were to determine the prevalence and serotype distribution of salmonella among reptiles in the education department (n = 55) at copenhagen zoo and compare it to the zoo's main reptile collection ...201322835051
on the different growth conditions affecting silver antimicrobial efficacy on listeria monocytogenes and salmonella enterica.silver is known to inhibit microorganisms and therefore it is an ideal candidate for its incorporation in a wide variety of materials for food applications. however, there is still a need for understanding how silver prolonged exposure to bacterial contamination affects the bioavailability of the active silver species. in the present study, growth curves of listeria monocytogenes and salmonella enterica were performed for 3-5 days in tryptic soy broth (tsb) and m9 minimal medium (m9) in the pres ...201222835228
combined genomarkers approach to salmonella characterization reveals that nucleotide sequence differences in the phase 1 flagellin gene flic are markers for variation within serotypes.the characterization and tracking of pathogenic micro-organisms in the clinical laboratory and public health environment demand schemes that are easy to standardize and use, are automated and high-throughput, and provide portable data. a combined genomarkers approach for salmonella enterica based on comparative sequence analysis by mass spectrometry has been developed. the scheme targets genes encoding synthesis and assembly of antigens, metabolic pathway enzymes, virulence factors and fluoroqui ...201222837220
several enteropathogens are circulating in suckling and newly weaned piglets suffering from diarrhea in the province of villa clara, cuba.intestinal contents of suckling (n = 45) and newly weaned (n = 45) piglets, suffering from diarrhea in the province of villa clara in cuba, were tested for viral, bacterial, and parasitic enteropathogens from may to june 2008. at least one enteropathogen was identified in 53.3 % of piglets and enterotoxigenic escherichia coli (etec; 25.6 %) was the major pathogen; mostly sta(+)/stb(+) or f4(+)/sta(+)/stb(+) etec were isolated. the overall occurrence of the rest of pathogens was 10 % for transmis ...201322843242
obacunone represses salmonella pathogenicity islands 1 and 2 in an envz-dependent fashion.obacunone belongs to a class of unique triterpenoids called limonoids, present in citrus species. previous studies from our laboratory suggested that obacunone possesses antivirulence activity and demonstrates inhibition of cell-cell signaling in vibrio harveyi and escherichia coli o157:h7. the present work sought to determine the effect of obacunone on the food-borne pathogen salmonella enterica serovar typhimurium lt2 by using a cdna microarray. transcriptomic studies indicated that obacunone ...201222843534
cpg oligonucleotides and recombinant interferon-γ in combination improve protection in chickens to salmonella enterica serovar enteritidis challenge as an adjuvant component, but have no effect in reducing salmonella carriage in infected chickens.salmonella enterica serovar enteritidis is the most common cause of human salmonellosis in many developed nations. it is frequently associated with both poultry meat and eggs. in the present study we have determined whether cpg oligonucleotides that stimulate the immune system via toll like-receptors 15 and 21 in the chicken can be used as immunomodulatory agents to break carriage of s. enteritidis in in vitro and in vivo infection models. we also investigated its use as a component in an adjuva ...201222845324
social networks and the spread of salmonella in a sleepy lizard population.although theoretical models consider social networks as pathways for disease transmission, strong empirical support, particularly for indirectly transmitted parasites, is lacking for many wildlife populations. we found multiple genetic strains of the enteric bacterium salmonella enterica within a population of australian sleepy lizards (tiliqua rugosa), and we found that pairs of lizards that shared bacterial genotypes were more strongly connected in the social network than were pairs of lizards ...201222845647
study on antibacterial alginate-stabilized copper nanoparticles by ft-ir and 2d-ir correlation spectroscopy.the objective of this study was to clarify the intermolecular interaction between antibacterial copper nanoparticles (cu nps) and sodium alginate (naalg) by fourier transform infrared spectroscopy (ft-ir) and to process the spectra applying two-dimensional infrared (2d-ir) correlation analysis. to our knowledge, the addition of naalg as a stabilizer of copper nanoparticles has not been previously reported. it is expected that the obtained results will provide valuable additional information on: ...201222848180
promoter strength driving tetr determines the regulatory properties of tet-controlled expression systems.bacteria frequently rely on transcription repressors and activators to alter gene expression patterns in response to changes in the surrounding environment. tet repressor (tetr) is a paradigm transcription factor that senses the environmental state by binding small molecule effectors, the tetracyclines. however, recently isolated peptides that act as inducers of tetr after having been fused to the c-terminus of a carrier protein, suggest that tetr can also regulate gene expression in a signal-tr ...201222848546
influence of methodologic aspects on the results of implant-abutment interface microleakage tests: a critical review of in vitro studies.this study sought to evaluate the influence of methodologic aspects on variations in the findings of in vitro microleakage studies of the implant-abutment interface.201522848880
whole blood-derived microrna signatures in mice exposed to lipopolysaccharides.lipopolysaccharide (lps) is recognized as the most potent microbial mediator presaging the threat of invasion of gram-negative bacteria that implicated in the pathogenesis of sepsis and septic shock. this study was designed to examine the microrna (mirna) expression in whole blood from mice injected with intraperitoneal lps.201222849760
effect of systemic infection induced by pseudomonas aeruginosa on the brain uptake of colistin in mice.in view of reports of colistin-induced neurotoxicity in infected patients, the aim of this study was to assess whether the integrity of the blood-brain barrier (bbb) and the brain uptake of colistin are altered in the presence of systemic pseudomonas aeruginosa infection. bacteremia was confirmed 8 h after intramuscular administration of p. aeruginosa atcc 27853 to swiss outbred mice, at which time a single subcutaneous dose of colistin sulfate (40 mg/kg of body weight) or an intravenous dose of ...201222850514
immune response to liposome-associated recombinant sef21 following oral immunization in chickens.in order to generate salmonella enterica serovar enteritidis fimbriae antigens (rsef21), the intact region encoding sef21 was amplified from salmonella enteritidis by pcr and subcloned into a prokaryotic expression vector pet-28a(+) to yield pet-28a(+)-sef21. the rsef21 protein was highly expressed and purified by nickel affinity chromatography. liposomeassociated rsef21 was prepared for oral immunization to seek protective efficacy for intestinal infection with salmonella enteritidis. evidence ...201222856192
efficacy of soluble recombinant flic protein from salmonella enterica serovar enteritidis as a potential vaccine candidate against homologous challenge in chickens.flic, the flagellin antigen of salmonella enteritidis, was tested as a vaccine candidate for protective effect against a homologous challenge in chickens. after immunization with recombinant flic (rflic) or administration of phosphate-buffered saline (pbs) at 56 days old, the chickens were challenged with 10(9) colony-forming units of salmonella enteritidis at 76 days old. the vaccinated birds showed significantly decreased bacterial counts in the liver and cecal contents compared to those admin ...201222856193
tandem attenuators control expression of the salmonella mgtcbr virulence operon.the mgtcbr operon from salmonella enterica serovar typhimurium specifies the virulence protein mgtc, the mg(2+) transporter mgtb and the regulatory peptide mgtr. the mgtcbr transcript includes a long leader region harbouring two short open reading frames (orfs). translation of these orfs is anticipated to impact the formation of particular stem-loop structures and control transcription of the coding region by an attenuation-like mechanism. we previously reported that orf mgtm enables salmonella ...201222857388
cross-reactive gut-directed immune response against salmonella enterica serovar paratyphi a and b in typhoid fever and after oral ty21a typhoid vaccination.there are no vaccines against paratyphoid fever in clinical use. the disease has become more wide-spread and there is a growing problem of antibiotic resistance among the strains. previous reports suggest that the oral live salmonella typhi ty21a-vaccine confers protection against paratyphoid b fever. data on efficacy against paratyphoid a fever are somewhat contentious. the present study investigated the immunological basis for such efficacy reports at a single-cell level: plasmablasts (identif ...201222858557
a genomic island in salmonella enterica ssp. salamae provides new insights on the genealogy of the locus of enterocyte effacement.the genomic island encoding the locus of enterocyte effacement (lee) is an important virulence factor of the human pathogenic escherichia coli. lee typically encodes a type iii secretion system (t3ss) and secreted effectors capable of forming attaching and effacing lesions. although prominent in the pathogenic e. coli such as serotype o157:h7, lee has also been detected in citrobacter rodentium, e. albertii, and although not confirmed, it is likely to also be in shigella boydii. previous phyloge ...201222860002
high pressure treatments on the inactivation of salmonella enteritidis and the characteristics of beef carpaccio.the effect of high pressure (hp) on salmonella enterica subsp. enterica serovar enteritidis in beef carpaccio stored under temperature abuse conditions (8 °c) during 30 days was investigated. after treatment, reductions of s. enteritidis were 3.68 and 5.94 log cfu/g in samples pressurized at 450 mpa for 5 and 10 min, respectively, whereas the pathogen was only detected after enrichment of samples treated at 450 mpa for 15 min. during storage, counts of s. enteritidis decreased 0.26 log cfu/g in ...201222863078
multiple pathways of duplication formation with and without recombination (reca) in salmonella enterica.duplications are often attributed to "unequal recombination" between separated, directly repeated sequence elements (>100 bp), events that leave a recombinant element at the duplication junction. however, in the bacterial chromosome, duplications form at high rates (10(-3)-10(-5)/cell/division) even without recombination (reca). here we describe 1800 spontaneous lac duplications trapped nonselectively on the low-copy f'(128) plasmid, where lac is flanked by direct repeats of the transposable ele ...201222865732
reduced na+ affinity increases turnover of salmonella enterica serovar typhimurium melb.the melibiose permease of salmonella enterica serovar typhimurium (melb(st)) catalyzes symport of melibiose with na(+), li(+), or h(+). bioinformatics and mutational analyses indicate that a conserved gly117 (helix iv) is a component of the na(+)-binding site. in this study, gly117 was mutated to ser, asn, or cys. all three mutations increase the maximum rate (v(max)) for melibiose transport in escherichia coli dw2 and greatly decrease na(+) affinity, indicating that intracellular release of na( ...201222865849
grapefruit juice and its constituents augment the effect of low ph on inhibition of survival and adherence to intestinal epithelial cells of salmonella enterica serovar typhimurium pt193.the present study examined the survival of salmonella typhimurium and its adherence to intestinal epithelial cells following inoculation into grapefruit juice and apple cider. both liquids significantly inactivated s. typhimurium (0.8-2.2 log reduction compared to the control); surviving salmonella in grapefruit juice was 1.0-1.4 log lower than in apple cider at 24h incubation. grapefruit juice contains the antimicrobial substances naringin (nar) and naringenin (nge); however, the effect of grap ...201222867848
hemophagocytic macrophages in murine typhoid fever have an anti-inflammatory phenotype.histiocytes are white blood cells of the monocytic lineage and include macrophages and dendritic cells. in patients with a variety of infectious and noninfectious inflammatory disorders, histiocytes can engulf nonapoptotic leukocytes and nonsenescent erythrocytes and thus become hemophagocytes. we report here the identification and characterization of splenic hemophagocytes in a natural model of murine typhoid fever. the development of a flow-cytometric method allowed us to identify hemophagocyt ...201222868497
the asd(+)-dadb(+) dual-plasmid system offers a novel means to deliver multiple protective antigens by a recombinant attenuated salmonella vaccine.we developed means to deliver multiple heterologous antigens on dual plasmids with non-antibiotic-resistance markers in a single recombinant attenuated vaccine strain of salmonella enterica serotype typhimurium. the first component of this delivery system is a strain of s. typhimurium carrying genomic deletions in alr, dadb, and asd, resulting in obligate requirements for diaminopimelic acid (dap) and d-alanine for growth. the second component is the asd(+)-dadb(+) plasmid pair carrying wild-typ ...201222868499
farm-level associations with the shedding of salmonella and antimicrobial-resistant salmonella in u.s. dairy cattle.salmonella enterica is the leading cause of foodborne-related deaths and hospitalizations within the united states. infections caused by antimicrobial-resistant (amr) strains are associated with higher hospital costs and case fatality. the objective for this study was to determine the association of management practices with the recovery of salmonella and amr salmonella on dairy herds. individual adult cow fecal samples and/or composite fecal samples were collected from 265 dairy herds in 17 sta ...201222870913
characterization of extended-spectrum beta-lactamase-producing salmonella enterica serotype brunei and heidelberg at the hussein dey hospital in algiers (algeria).the purpose of this work was to study the genetic determinants responsible for extended-spectrum cephalosporin (esc) resistance of salmonella collected during the period of 1995-2008 at the hussein dey hospital in algiers (algeria). fourteen esc-resistant salmonella isolates were tested towards 22 antimicrobial agents. polymerase chain reaction (pcr) and sequencing were used to determine the underlying genetic determinants responsible for the extended-spectrum beta-lactamase (esbl) phenotypes. e ...201222871227
antisense transcription is pervasive but rarely conserved in enteric bacteria.noncoding rnas, including antisense rnas (asrnas) that originate from the complementary strand of protein-coding genes, are involved in the regulation of gene expression in all domains of life. recent application of deep-sequencing technologies has revealed that the transcription of asrnas occurs genome-wide in bacteria. although the role of the vast majority of asrnas remains unknown, it is often assumed that their presence implies important regulatory functions, similar to those of other nonco ...201222872780
genome-wide detection of spontaneous chromosomal rearrangements in bacteria.genome rearrangements have important effects on bacterial phenotypes and influence the evolution of bacterial genomes. conventional strategies for characterizing rearrangements in bacterial genomes rely on comparisons of sequenced genomes from related species. however, the spectra of spontaneous rearrangements in supposedly homogenous and clonal bacterial populations are still poorly characterized. here we used 454 pyrosequencing technology and a 'split mapping' computational method to identify ...201222880062
assessment of a regulatory sanitization process in egyptian dairy plants in regard to the adherence of some food-borne pathogens and their biofilms.food-borne pathogens may develop certain strategies that enable them to defy harsh conditions such as chemical sanitization. biofilm formation represents a prominent one among those adopted strategies, by which food-borne pathogens protect themselves against external threats. thus, bacterial biofilm is considered as a major hazard for safe food production. this study was designed to investigate the adherence and the biofilm formation ability of some food-borne pathogens on stainless steel and po ...201222884171
electrochemical detection of salmonella using gold nanoparticles.a disposable immunosensor for salmonella enterica subsp. enterica serovar typhimurium lt2 (s) detection using a magneto-immunoassay and gold nanoparticles (aunps) as label for electrochemical detection is developed. the immunosensor is based on the use of a screen-printed carbon electrode (spce) that incorporates a permanent magnet underneath. salmonella containing samples (i.e. skimmed milk) have been tested by using anti-salmonella magnetic beads (mbs-psab) as capture phase and sandwiching aft ...201322884647
emergence of fluoroquinolone resistance in salmonella enterica serovar typhi in andaman and nicobar islands, india. 201222885270
phosphorylation of nlrc4 is critical for inflammasome activation.nlrc4 is a cytosolic member of the nod-like receptor family that is expressed in innate immune cells. it senses indirectly bacterial flagellin and type iii secretion systems, and responds by assembling an inflammasome complex that promotes caspase-1 activation and pyroptosis. here we use knock-in mice expressing nlrc4 with a carboxy-terminal 3×flag tag to identify phosphorylation of nlrc4 on a single, evolutionarily conserved residue, ser 533, following infection of macrophages with salmonella e ...201222885697
human infections attributable to the d-tartrate-fermenting variant of salmonella enterica serovar paratyphi b in germany originate in reptiles and, on rare occasions, poultry.in this study, the population structure, incidence, and potential sources of human infection caused by the d-tartrate-fermenting variant of salmonella enterica serovar paratyphi b [s. paratyphi b (dt+)] was investigated. in germany, the serovar is frequently isolated from broilers. therefore, a selection of 108 epidemiologically unrelated s. enterica serovar paratyphi b (dt+) strains isolated in germany between 2002 and 2010 especially from humans, poultry/poultry meat, and reptiles was investig ...201222885742
epidemiology of a salmonella enterica subsp. enterica serovar typhimurium strain associated with a songbird outbreak.salmonella enterica subsp. enterica serovar typhimurium is responsible for the majority of salmonellosis cases worldwide. this salmonella serovar is also responsible for die-offs in songbird populations. in 2009, there was an s. typhimurium epizootic reported in pine siskins in the eastern united states. at the time, there was also a human outbreak with this serovar that was associated with contaminated peanuts. as peanuts are also used in wild-bird food, it was hypothesized that the pine siskin ...201222885752
detection of salmonella enterica isolates producing ctx-m cephalosporinase in u.s. livestock populations.we report the detection of salmonella carrying bla(ctx-m) in u.s. livestock populations. we identified 12 of 2,034 (0.6%) salmonella isolates originating from turkeys, horses, and pigs from at least 6 u.s. states, all carrying bla(ctx-m-1), many on a pandemic sequence type 1 incn plasmid.201222885753
pathways of genetic adaptation: multistep origin of mutants under selection without induced mutagenesis in salmonella enterica.in several bacterial systems, mutant cell populations plated on growth-restricting medium give rise to revertant colonies that accumulate over several days. one model suggests that nongrowing parent cells mutagenize their own genome and thereby create beneficial mutations (stress-induced mutagenesis). by this model, the first-order induction of new mutations in a nongrowing parent cell population leads to the delayed accumulation of visible colonies. in an alternative model (selection only), sel ...201222887815
bacterial infection of macrophages induces decrease in refractive index.infection of cells by pathogens leads to both biochemical and structural modifications of the host cell. to study the structural modifications in a label-free manner, we use digital holographic microscopy, dhm, to obtain the integral refractive index distribution of cells. primary murine bone marrow derived macrophages (bmdm) infected with salmonella enterica serovar typhimurium, undergo highly significant reduction in refractive index, ri, compared to uninfected cells. infected bmdm cells from ...201322887897
evolution of a multiple antibiotic resistance region in inchi1 plasmids: reshaping resistance regions in situ.to determine the structure of the resistance region in an inchi1 plasmid conferring resistance to multiple antibiotics, including gentamicin, recovered from a salmonella enterica serovar typhimurium isolate from a horse.201222888274
low-shear modeled microgravity enhances salmonella enterica resistance to hydrogen peroxide through a mechanism involving katg and katn.studies carried out in recent years have established that growth under conditions of reduced gravity enhances salmonella enterica serovar typhimurium virulence. to analyze the possibility that this microgravity-induced increase in pathogenicity could involve alterations in the ability of salmonella to withstand oxidative stress, we have compared the resistance to hydrogen peroxide of various salmonella enterica strains grown under conditions of low shear modeled microgravity (lsmmg) or normal gr ...201222888375
investigation into the role of five salmonella enterica serovar enteritidis genomic islands in colonization of the chicken reproductive tract and other organs following oral challenge.salmonella enterica serovar enteritidis is a major cause of human gastrointestinal tract disease, infection being due in large part to the consumption of contaminated eggs. recent genome sequencing of s. enterica serovars has identified genomic islands, the presence of which differs between serovars. using defined mutants, we have investigated the contribution that five such loci play in the colonization of the avian reproductive tract, other organs and avian macrophages. all loci appear to play ...201222889182
non-genetic diversity shapes infectious capacity and host resistance.the spontaneous generation of distinct phenotypes within a clonal population of cells allows for both bet-hedging at the population level and the division of labor among subpopulations. this is emerging as an important theme in bacterial pathogenesis, because bacterial pathogens exhibit phenotypic heterogeneity with respect to characteristics that impact virulence. the phenomenon of persister cells and models of salmonella enterica serovar typhimurium (s. typhimurium) pathogenesis illustrate the ...201222889945
differential modulation of intracellular survival of cytosolic and vacuolar pathogens by curcumin.curcumin, a principal component of turmeric, acts as an immunomodulator regulating the host defenses in response to a diseased condition. the role of curcumin in controlling certain infectious diseases is highly controversial. it is known to alleviate symptoms of helicobacter pylori infection and exacerbate that of leishmania infection. we have evaluated the role of curcumin in modulating the fate of various intracellular bacterial pathogens. we show that pretreatment of macrophages with curcumi ...201222890770
biofilm formation, cell surface hydrophobicity, and fatty acids analysis of starved salmonella enterica serovar typhimurium in seawater.salmonella is an international foodborne pathogen widely disseminated in seawater that regularly causes large outbreaks of food poisoning. in this study, we have investigated the effect of starvation on the ability of salmonella enterica serovar typhimurium cells to adhere to polystyrene microplate and hep2 cells in seawater microcosms after incubation for 3 years. cell surface hydrophobicity was evaluated. effect of stress on fatty acids composition was also established. our results showed that ...201222891961
salmonella "sops" up a preferred electron receptor in the inflamed intestine.the microbiota of the mammalian intestinal tract represents a formidable barrier to colonization by pathogens. to overcome this resistance to colonization, bacterial pathogens use virulence factors to induce intestinal inflammation, which liberates nutrients for selective use by the infecting microbe. studies of salmonella enterica serovar typhimurium (s. typhimurium) infection in a streptomycin-treated mouse colitis model show how virulence factor-induced inflammation can produce nutrients used ...201222893385
[protection against salmonella via immunization with recombinant lactic acid bacteria].mucosal immunization of hens may be effective to prevent contamination of salmonella enterica serovar enteritidis (se) in eggs. lactic acid bacteria have been considered potential vaccine delivery agents because they are safe, immunogenic, and inexpensive. our research group has been investigating the development of oral vaccines against se using a lactobacillus casei strain as an antigen delivery vehicle. recombinant lactobacilli expressing se antigens flic and sipc have been constructed and ad ...201222894061
caspase-11 increases susceptibility to salmonella infection in the absence of caspase-1.inflammasomes are cytosolic multiprotein complexes assembled by intracellular nucleotide-binding oligomerization domain (nod)-like receptors (nlrs) and they initiate innate immune responses to invading pathogens and danger signals by activating caspase-1 (ref. 1). caspase-1 activation leads to the maturation and release of the pro-inflammatory cytokines interleukin (il)-1β and il-18, as well as lytic inflammatory cell death known as pyroptosis. recently, a new non-canonical inflammasome was desc ...201222895188
suppressor analyses identify threonine as a modulator of rida mutant phenotypes in salmonella enterica.the rida (yjgf/yer057c/uk114) family of proteins is broadly conserved in the three domains of life yet the functional understanding of these proteins is at an early stage. physiological studies of rida mutant strains of salmonella enterica provided a framework to inform in vitro studies and led to the description of a conserved biochemical activity for this family. rida mutant strains of s. enterica have characteristic phenotypes including new synthesis of thiamine biosynthetic intermediate phos ...201222900093
a comprehensive subcellular proteomic survey of salmonella grown under phagosome-mimicking versus standard laboratory conditions.towards developing a systems-level pathobiological understanding of salmonella enterica, we performed a subcellular proteomic analysis of this pathogen grown under standard laboratory and phagosome-mimicking conditions in vitro. analysis of proteins from cytoplasmic, inner membrane, periplasmic, and outer membrane fractions yielded coverage of 25% of the theoretical proteome. confident subcellular location could be assigned to over 1000 proteins, with good agreement between experimentally observ ...201222900174
bacterial pathogens commandeer rab gtpases to establish intracellular niches.intracellular bacterial pathogens deploy virulence factors termed effectors to inhibit degradation by host cells and to establish intracellular niches where growth and differentiation take place. here, we describe mechanisms by which human bacterial pathogens (including chlamydiae; coxiella burnetii; helicobacter pylori; legionella pneumophila; listeria monocytogenes; mycobacteria; pseudomonas aeruginosa, salmonella enterica) modulate endocytic and exocytic rab gtpases in order to thrive in host ...201222901006
prevalence, antimicrobial resistance and relation to indicator and pathogenic microorganisms of salmonella enterica isolated from surface waters within an agricultural landscape.during a 12 month period (june 2007-may 2008), the prevalence and susceptibility of salmonella serovars and their relation to specific pathogenic and indicator bacteria in river and coastal waters was investigated. a total of 240 water samples were collected from selected sites in acheron and kalamas rivers and the ionian sea coast in north western greece. the samples were analyzed for salmonella spp., listeria spp., campylobacter spp., escherichia coli o157, staphylococci, pseudomonas spp., tot ...201322901425
immediate after birth transmission of epidemic salmonella enterica typhimurium monophasic strains in pigs is a likely event. 201222904242
functional analysis of the genes encoding diaminopropionate ammonia lyase in escherichia coli and salmonella enterica serovar typhimurium.diaminopropionate ammonia lyase (dapal) is a pyridoxal-5'phosphate (plp)-dependent enzyme that catalyzes the conversion of diaminopropionate (dap) to pyruvate and ammonia and plays an important role in cell metabolism. we have investigated the role of the ygex gene of escherichia coli k-12 and its ortholog, stm1002, in salmonella enterica serovar typhimurium lt2, presumed to encode dapal, in the growth kinetics of the bacteria. while salmonella typhimurium lt2 could grow on dl-dap as a sole carb ...201222904288
fis is essential for the stability of linear plasmid pbssb1 and affects the motility of salmonella enterica serovar typhi.pbssb1 is a 27 kb non-bacteriophage-related linear plasmid first found in salmonella enterica serovar typhi (s. typhi), but the mechanism underlying the replication of pbssb1 is currently unknown. previous reports showed that the factor for inversion stimulation (fis) encoded by fis can affect the replication, transcription and other processes through binding dna. here, a fis deletion mutant of s. typhi (δfis) was prepared through the homologous recombination mediated by suicide plasmid and the ...201222911678
bacteria and protozoa differentially modulate the expression of rab proteins.phagocytic cells represent an important line of innate defense against microorganisms. uptake of microorganisms by these cells involves the formation of a phagosome that matures by fusing with endocytic compartments, resulting in killing of the enclosed microbe. small gtpases of the rab family are key regulators of vesicular trafficking in the endocytic pathway. intracellular pathogens can interfere with the function of these proteins in order to subvert host immune responses. however, it is unk ...201222911692
oral administration of a combination of select lactic acid bacteria strains to reduce the salmonella invasion and inflammation of broiler chicks.one-day-old chicks are susceptible to infection by strains of salmonella enterica subspecies. because multistrain probiotics are suggested to be more effective than monostrain probiotics due to the additive and synergistic effects, in this study, we prepared a multistrain formula a (mfa) consisting of 4 lactic acid bacteria (lab) strains selected by enhancing the tnf-α production for mouse macrophage 264.7 cells. the antagonistic effect of this mfa against the cecal colonization, viscera invasiv ...201222912447
polyfunctional cd4+ t cell responses to immunodominant epitopes correlate with disease activity of virulent salmonella.salmonella enterica serovars are intracellular bacteria capable of causing typhoid fever and gastroenteritis of significant morbidity and mortality worldwide. current prophylactic and therapeutic treatment is hampered by the emergence of multidrug-resistant (mdr) strains of salmonella, and vaccines provide only temporal and partial protection in vaccinees. to develop more effective salmonella vaccines, it is important to understand the development of protective adaptive immunity to virulent salm ...201222912884
rates of gyrase supercoiling and transcription elongation control supercoil density in a bacterial chromosome.gyrase catalyzes negative supercoiling of dna in an atp-dependent reaction that helps condense bacterial chromosomes into a compact interwound "nucleoid." the supercoil density (σ) of prokaryotic dna occurs in two forms. diffusible supercoil density (σ(d)) moves freely around the chromosome in 10 kb domains, and constrained supercoil density (σ(c)) results from binding abundant proteins that bend, loop, or unwind dna at many sites. diffusible and constrained supercoils contribute roughly equally ...201222916023
dbdiarrhea: the database of pathogen proteins and vaccine antigens from diarrheal pathogens.diarrhea occurs world-wide and is most commonly caused by gastrointestinal infections which kill around 2.2 million people globally each year, mostly children in developing countries. we describe here dbdiarrhea, which is currently the most comprehensive catalog of proteins implicated in the pathogenesis of diarrhea caused by major bacterial, viral and parasitic species. the current release of the database houses 820 proteins gleaned through an extensive and critical survey of research articles ...201222917656
extreme antimicrobial peptide and polymyxin b resistance in the genus burkholderia.cationic antimicrobial peptides and polymyxins are a group of naturally occurring antibiotics that can also possess immunomodulatory activities. they are considered a new source of antibiotics for treating infections by bacteria that are resistant to conventional antibiotics. members of the genus burkholderia, which includes various human pathogens, are inherently resistant to antimicrobial peptides. the resistance is several orders of magnitude higher than that of other gram-negative bacteria s ...201122919572
cationic antimicrobial peptides serve as activation signals for the salmonella typhimurium phopq and pmrab regulons in vitro and in vivo.salmonella enterica serovar typhimurium uses two-component regulatory systems (tcrss) to respond to environmental stimuli. upon infection, the tcrss phop-phoq (phopq) and pmra-pmrb (pmrab) are activated by environmental signals detected in the lumen of the intestine and within host cells. tcrs-mediated gene expression leads to upregulation of genes involved in lipopolysaccharide (lps) modification and cationic antimicrobial peptide (camp) resistance. this research expands on previous studies whi ...201222919691
the effect of low shear force on the virulence potential of yersinia pestis: new aspects that space-like growth conditions and the final frontier can teach us about a formidable pathogen.manned space exploration has created a need to evaluate the effects of space-like stress (sls) on pathogenic and opportunistic microbes. interestingly, several gram-negative enteric pathogens, e.g., salmonella enterica serovar typhimurium, have revealed a transient hyper-virulent phenotype following simulated microgravity (smg) or actual space flight exposures. we have explored the virulence potential of yersinia pestis kim/d27 (yp) following exposure to mechanical low shear forces associated wi ...201222919696
escherichia coli strongly supports the growth of histomonas meleagridis, in a monoxenic culture, without influence on its pathogenicity.based on clonal cultures of histomonas meleagridis, monoxenic cultures have, to our knowledge for the first time, been established in a liquid medium. the faecal flora was exchanged for defined bacterial strains by selective destruction of the initial bacteria with a variety of antibiotics, keeping the flagellate alive. the growth of the protozoan parasite was found to depend on the bacteria, especially on their energy metabolism. escherichia coli was found to strongly support the growth of the ...201222921600
reciprocal control between a bacterium's regulatory system and the modification status of its lipopolysaccharide.gram-negative bacteria often modify their lipopolysaccharide (lps), thereby increasing resistance to antimicrobial agents and avoidance of the host immune system. however, it is unclear how bacteria adjust the levels and activities of lps-modifying enzymes in response to the modification status of their lps. we now address this question by investigating the major regulator of lps modifications in salmonella enterica. we report that the pmra/pmrb system controls expression of a membrane peptide t ...201222921935
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