Publications

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antibacterial activity of a novel fatty acid (14e, 18e, 22e, 26e)-methyl nonacosa-14, 18, 22, 26 tetraenoate isolated from amaranthus spinosus.amaranthus spinosus linn. (amaranthaceae), commonly known as ''spiny pigweed'', is used in both indian traditional system and folk medicine for treatment of infectious diseases for a long time in several traditional herbal medicinal preparations. a novel fatty acid [(14e, 18e, 22e, 26e)-methyl nonacosa-14, 18, 22, 26 tetraenoate] is the major metabolite present.201627043360
anticancer and antibacterial secondary metabolites from the endophytic fungus penicillium sp. cam64 against multi-drug resistant gram-negative bacteria.the emergence of multiple-drug resistance bacteria has become a major threat and thus calls for an urgent need to search for new effective and safe anti-bacterial agents.201627917206
antibacterial and cytotoxic cytochalasins from the endophytic fungus phomopsis sp. harbored in garcinia kola (heckel) nut.the continuous emergence of multidrug-resistant (mdr) bacteria drastically reduced the efficacy of our antibiotic armory and consequently, increased the frequency of therapeutic failure. the search for bioactive constituents from endophytic fungi against mdr bacteria became a necessity for alternative and promising strategies, and for the development of novel therapeutic solutions. we report here the isolation and structure elucidation of antibacterial and cytotoxic compounds from phomopsis sp., ...201627842536
characterization of prohibitin 1 as a host partner of vibrio vulnificus rtxa1 toxin.rtxa1 toxin, which results in cytoskeletal rearrangement, contact cytotoxicity, hemolysis, tissue invasion, and lethality in mice, is the most potent cytotoxic virulence factor of vibrio vulnificus. bioinformatics analysis of rtxa1 predicted 4 functional domains that presumably performed discrete functions during host cell killing. v. vulnificus rtxa1 has a unique domain designated as rtxa1-d2, corresponding to amino acids 1951-2574, which is absent in vibrio cholerae multifunctional-autoprocess ...201626136468
synthesis and biological evaluation of 5,7-dihydroxyflavanone derivatives as antimicrobial agents.a series of 5,7-dihydroxyflavanone derivatives were efficiently synthesized. their antimicrobial efficacy on gram-negative, gram-positive bacteria and yeast were evaluated. among these compounds, most of the halogenated derivatives exhibited the best antimicrobial activity against gram-positive bacteria, the yeast saccharomyces cerevisiae, and the gram-negative bacterium vibrio cholerae. the cytotoxicities of these compounds were low as evaluated on hepg2 cells using a cell viability assay. this ...201627210435
[n-acetyl-β-d-glucosaminidase of vibrio cholerae].study n-acetyl-β-d-glucosaminidase (chitobiase) (ec 3.2.1.30) in strains of vibrio cholerae of o1/non-o1 serogroups of various origin, that is a component of chitinolytic complex taking into account object of isolation and epidemiologic significance of strains.201627228670
development of lipopolysaccharide-mimicking peptides and their immunoprotectivity against vibrio cholerae serogroup o1.vibrio cholerae serogroup o1 is the main causative agent of cholera diseases defined by life threatening rice watery diarrhea. cholera routine vaccination has failed in controlling epidemics in developing countries because of their hard and expensive production. in this study, our aim was to investigate phage displayed mimotopes that could mimic v. cholerae lipopolysaccharide (lps). although lps of vibrio, as an endotoxin, can stimulate the immune system, thereby making it a suitable candidate f ...201627766741
local and global consequences of flow on bacterial quorum sensing.bacteria use a chemical communication process called quorum sensing (qs) to control collective behaviours such as pathogenesis and biofilm formation(1,2). qs relies on the production, release and group-wide detection of signal molecules called autoinducers. to date, studies of bacterial pathogenesis in well-mixed cultures have revealed virulence factors and the regulatory circuits controlling them, including the overarching role of qs(3). although flow is ubiquitous to nearly all living systems( ...201627571752
molecular detection of the three major pathogenic vibrio species from seafood products and sediments in tunisia using real-time pcr.vibrio spp. have emerged as a serious threat to human health worldwide. v. parahaemolyticus , v. cholerae , and v. vulnificus pose a considerable public health risk in tunisia because they cause sporadic and epidemic foodborne infections associated with the consumption of raw or undercooked contaminated seafood. more recently, toxr-positive v. alginolyticus was also reported to be a potential source of contaminated seafood. a total of 247 samples, including 113 fishes ( labrus viridis , penaeus ...201628221954
world health organization estimates of the relative contributions of food to the burden of disease due to selected foodborne hazards: a structured expert elicitation.the foodborne disease burden epidemiology reference group (ferg) was established in 2007 by the world health organization (who) to estimate the global burden of foodborne diseases (fbds). this estimation is complicated because most of the hazards causing fbd are not transmitted solely by food; most have several potential exposure routes consisting of transmission from animals, by humans, and via environmental routes including water. this paper describes an expert elicitation study conducted by t ...201626784029
treatment of diarrhoea using traditional medicines: contemporary research in south africa and zimbabwe.gastrointestinal disorders, diarrhoea in particular remain a major concern in south africa and zimbabwe resulting in high mortality rates when left untreated. this investigation was aimed at documenting herbal medicines used in the treatment of diarrhoea in south africa and zimbabwe.201628480353
preparation, characterization and antibacterial activity of chitosan and phosphorylated chitosan from cuttlebone of sepia kobiensis (hoyle, 1885).chitosan is a commercially available derivative of chitin that has been extensively studied for its antimicrobial properties. in order to improve the water solubility and its biological activity, the chemical modification or derivatisation is attempted. in the present investigation, the chitosan prepared from the cuttlebone of sepia kobiensis was being chemically modified by reacting it with orthophosphoric acid so as to obtain phosphorylated chitosan. then the chitosan and phosphorylated chitos ...201628507912
ctxb1 outcompetes ctxb7 in vibrio cholerae o1, bangladesh. 201626487638
surviving the acid barrier: responses of pathogenic vibrio cholerae to simulated gastric fluid.when bacteria are subjected to low acidic phs of the gastric environment, they may enter the viable but nonculturable (vbnc) state of survival. in this state, bacteria cannot be cultured on solid media, still exhibit signs of metabolic activity (viability). in this study, the response of pathogenic vibrio cholerae o1 and o139 to low ph-simulated environments of the human stomach was evaluated for their survival by culturability (plate count) and viability (flow cytometry-fc) assays. bacteria wer ...201626496916
non-o1, non-o139 vibrio cholerae bacteremic skin and soft tissue infections.non-o1, non-o139 vibrio cholerae can cause sporadic cases of gastroenteritis and extra-intestinal invasive infections, following exposure to contaminated seawater or freshwater or after consumption of raw seafood. bacteremic infections with skin and soft tissue manifestations are uncommon and in most cases are associated with liver cirrhosis, haematologic malignancies, diabetes mellitus and other immunosuppressed conditions.201626503346
identification of vibrio cholerae serotypes in high-risk marine products with non-gel sieving capillary electrophoresis.vibrio cholerae, a natural inhabitant of the marine environment, poses a threat to human health, and its new epidemic variants have been reported. a method of multiplex polymerase chain reaction-capillary electrophoresis-laser-induced fluorescence (pcr-ce-lif) detection has been developed to detect and identify v. cholerae in marine products sensitively, rapidly, and reliably. four sets of primers were selected to amplify genus-specific vcc gene, o139 serogroup-specific o139 gene, o1 serogroup-s ...201626548956
parallel quorum sensing signaling pathways in vibrio cholerae.quorum sensing (qs) is a microbial signaling process for monitoring population density and complexity. communication among bacterial cells via qs relies on the production, secretion, and detection of small molecules called autoinducers. many bacteria have evolved their qs systems with different network architectures to incorporate information from multiple signals. in the human pathogen vibrio cholerae, at least four parallel signaling pathways converge to control the activity of a single regula ...201626545759
immunosensor based on nanocomposite of nanostructured zirconium oxide and gelatin-a.we have reported the studies related to the fabrication of a nanocomposite, comprising of sol-gel derived inorganic zirconium oxide nanoparticles (zro2 nps) and organic biopolymer gelatin-a (ga), deposited on indium-tin-oxide (ito) coated glass substrate by drop casting method. the ga-zro2/ito electrode was used for immobilization of monoclonal antibodies (ab) specific to antigen vibrio cholerae (vc) followed by bovine serum albumin (bsa) for antigen vc detection using electrochemical techniques ...201626515440
non-protein coding rna-based genosensor with quantum dots as electrochemical labels for attomolar detection of multiple pathogens.the ability of a diagnostic test to detect multiple pathogens simultaneously is useful to obtain meaningful information for clinical treatment and preventive measures. we report a highly sensitive and specific electrochemical biosensor assay for simultaneous detection of three gene targets using quantum dots (qds). the targets are novel non-protein coding rna (npcrna) sequences of vibrio cholerae, salmonella sp. and shigella sp., which cause diarrheal diseases. qds (pbs, cds, zns) were synthesiz ...201626513287
distribution and molecular characteristics of vibrio cholerae o1 el tor isolates recovered in guangdong province, china, 1961-2013.china's guangdong province is located along the same latitude as kolkata, india and dhaka, bangladesh, and is also considered a source of epidemic cholera. however, molecular description and the genetic relationships between vibrio cholerae o1 el tor isolates in guangdong remain unclear. in this study, 381 clinical v. cholerae o1 isolates recovered from cholera cases presenting in guangdong between 1961 and 2013 were investigated by pcr, amplicon sequencing and pulsed-field gel electrophoresis ( ...201626554719
vibrio cholerae o1 el tor from southern vietnam in 2010 was molecularly distinct from that present from 1999 to 2004.the vibrio cholerae o1 (vco1) el tor biotype appeared during the seventh cholera pandemic starting in 1961, and new variants of this biotype have been identified since the early 1990s. this pandemic has affected vietnam, and a large outbreak was reported in southern vietnam in 2010. pulsed-field gel electrophoresis (pfge) and multilocus variable-number tandem-repeat analyses (mlva) were used to screen 34 vco1 isolates from the southern vietnam 2010 outbreak (23 patients, five contact persons, an ...201626554547
molecular epidemiology of vibrio cholerae associated with flood in brahamputra river valley, assam, india.cholera is often caused when drinking water is contaminated through environmental sources. in recent years, the drastic cholera epidemics in odisha (2007) and haiti (2010) were associated with natural disasters (flood and earthquake). almost every year the state of assam india witnesses flood in brahamputra river valley during reversal of wind system (monsoon). this is often followed by outbreak of diarrheal diseases including cholera. beside the incidence of cholera outbreaks, there is lack of ...201626656743
hemagglutinin protease secreted by v. cholerae induced apoptosis in breast cancer cells by ros mediated intrinsic pathway and regresses tumor growth in mice model.conventional anticancer therapies are effective but have side effects, so alternative targets are being developed. bacterial toxins that can kill cells or alter the cellular processes like proliferation, apoptosis and differentiation have been reported for cancer treatment. in this study we have shown antitumor activity of hemagglutinin protease (hap) secreted by vibrio cholerae. one µg of hap showed potent antitumor activity when injected into ehrlich ascites carcinoma (eac) tumors in swiss alb ...201626558913
a new nano-worm structure from gold-nanoparticle mediated random curving of zinc oxide nanorods.creating novel nanostructures is a primary step for high-performance analytical sensing. herein, a new worm like nanostructure with zinc oxide-gold (zno/au) hybrid was fabricated through an aqueous hydrothermal method, by doping au-nanoparticle (aunp) on the growing zno lattice. during zno growth, fine tuning the solution temperature expedites random curving of zno nanorods and forms nano-worms. the nano-worms which were evidenced by morphological, physical and structural analyses, revealed elon ...201626584078
regulation of competence-mediated horizontal gene transfer in the natural habitat of vibrio cholerae.the human pathogen vibrio cholerae is an autochthonous inhabitant of aquatic environments where it often interacts with zooplankton and their chitinous molts. chitin induces natural competence for transformation in v. cholerae, a key mode of horizontal gene transfer (hgt). recent comparative genomic analyses were indicative of extensive hgt in this species. however, we can still expand our understanding of the complex regulatory network that drives competence in v. cholerae. here, we present rec ...201626615332
the dna-uptake process of naturally competent vibrio cholerae.the sophisticated dna-uptake machinery used during natural transformation is still poorly characterized, especially in gram-negative bacteria where the transforming dna has to cross two membranes as well as the peptidoglycan layer before entering the cytoplasm. the dna-uptake machinery was hypothesized to take the form of a pseudopilus, which, upon repeated cycles of extension and retraction, would pull external dna towards the cell surface or into the periplasmic space, followed by translocatio ...201626614677
role of the na(+)-translocating nadh:quinone oxidoreductase in voltage generation and na(+) extrusion in vibrio cholerae.for vibrio cholerae, the coordinated import and export of na(+) is crucial for adaptation to habitats with different osmolarities. we investigated the na(+)-extruding branch of the sodium cycle in this human pathogen by in vivo (23)na-nmr spectroscopy. the na(+) extrusion activity of cells was monitored after adding glucose which stimulated respiration via the na(+)-translocating nadh:quinone oxidoreductase (na(+)-nqr). in a v. cholerae deletion mutant devoid of the na(+)-nqr encoding genes (nqr ...201626721205
cholera toxin production induced upon anaerobic respiration is suppressed by glucose fermentation in vibrio cholerae.the causative agent of pandemic cholera, vibrio cholerae, infects the anaerobic environment of the human intestine. production of cholera toxin (ct), a major virulence factor of v. cholerae, is highly induced during anaerobic respiration with trimethylamine n-oxide (tmao) as an alternative electron acceptor. however, the molecular mechanism of tmao-stimulated ct production is not fully understood. herein, we reveal that ct production during anaerobic tmao respiration is affected by glucose ferme ...201626718467
validity of the estimates of oral cholera vaccine effectiveness derived from the test-negative design.the test-negative design (tnd) has emerged as a simple method for evaluating vaccine effectiveness (ve). its utility for evaluating oral cholera vaccine (ocv) effectiveness is unknown. we examined this method's validity in assessing ocv effectiveness by comparing the results of tnd analyses with those of conventional cohort analyses.201626707378
a luminescent hybridoma-based biosensor for rapid detection of v. cholerae upon induction of calcium signaling pathway.in this study, a hybridoma based biosensor was developed for rapid, sensitive and selective detection of vibrio cholerae o1 which converts the antibody-antigen binding to bioluminescence light. after investigation on hybridoma performance, the biosensor was constructed by transfecting specific hybridoma cells with aequorin reporter gene and the bioluminescence activities of stable biosensor were measured. the sensitivity of biosensor was as few as 50 cfu/ml and it showed no responses to other en ...201626706943
starch dust explosion and flame burn injury in a patient complicated with severe cellulites caused by non-o1 vibrio cholerae. 201626687236
characterization of environmental vibrio cholerae serogroups o1 and o139 in the pearl river estuary, china.toxigenic isolates of vibrio cholerae serogroups o1 and o139 from aquatic reservoirs are a key source for recurrent epidemics of cholera in human populations. however, we do not have an optimal understanding of the microbiology of the strains within these reservoirs, particularly outside of the time periods when there are active cholera cases in the surrounding community. the main objective of the present study was to identify and characterize v. cholerae o1 and o139 in the pearl river estuary a ...201626674584
nucleoside uptake in vibrio cholerae and its role in the transition fitness from host to environment.as it became evident recently, extracellular dna could be a versatile nutrient source of the facultative pathogen vibrio cholerae along the different stages of its life cycle. by the use of two extracellular nucleases and periplasmic phosphatases, v. cholerae degrades extracellular dna to nucleosides. in this study, we investigated the nucleoside uptake via identification and characterization of vca0179, vc1953 and vc2352 representing the three nucleoside transport systems in v. cholerae. based ...201626202476
vibrio cholerae o1 el tor variant and emergence of haitian ctxb variant in the strains isolated from south india.cholera still continues to be an important cause of human infection, especially in developing countries that lack access to safe drinking water and proper sanitation. in the present study, we report the emergence of new variant form of v. cholerae o1 el tor biotype with a novel mutation in ctxb in strains isolated from various outbreaks during 2010-2014 in belgaum situated in north-west karnataka, india. a total of 14 occurrences of cholera were documented from belgaum division of north karnatak ...201626337047
label-free electrochemical immunosensor based on cerium oxide nanowires for vibrio cholerae o1 detection.this paper developed a label-free immunosensor based on cerium oxide nanowire for vibrio cholerae o1 detection application. the ceo2 nanowires were synthesized by hydrothermal reaction. the immobilization of anti-v. cholerae o1 onto ceo2 nanowire-deposited sensor was performed via an amino ester, which was created by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and sulfo-n-hydroxysuccinimide. the electrochemical responses of the immunosensor were studied by electrochemical impedance spe ...201626478391
aeromonas chitinase degrades chironomid egg masses.chironomids are freshwater insects that undergo a complete metamorphosis of four life stages. chironomid egg masses can be degraded by vibrio cholerae and some aeromonas species. egg mass degradation by v. cholerae requires haemagglutinin protease activity. our aim was to identify the egg mass degrading (emd) factor secreted by aeromonas dhkanesis 3k1c15. following the hypothesis that the emd factor of a. dhkanesis is also a protease, secreted proteases were screened, but none of them proved to ...201626472256
incidence of severe diarrhoea due to vibrio cholerae in the catchment area of six surveillance hospitals in bangladesh.cholera is an important public health problem in bangladesh. interventions to prevent cholera depend on their cost-effectiveness which in turn depends on cholera incidence. hospital-based diarrhoeal disease surveillance has been ongoing in six bangladeshi hospitals where a systematic proportion of patients admitted with diarrhoea were enrolled and tested for vibrio cholerae. however, incidence calculation using only hospital data underestimates the real disease burden because many ill persons se ...201626391481
vibrio cholerae phosphatases required for the utilization of nucleotides and extracellular dna as phosphate sources.phosphate is essential for life, being used in many core processes such as signal transduction and synthesis of nucleic acids. the waterborne agent of cholera, vibrio cholerae, encounters phosphate limitation in both the aquatic environment and human intestinal tract. this bacterium can utilize extracellular dna (edna) as a phosphate source, a phenotype dependent on secreted endo- and exonucleases. however, no transporter of nucleotides has been identified in v. cholerae, suggesting that in orde ...201626175126
urinary tract infection due to nono1 vibrio cholerae. 201625553995
a new epithelial cell line, hbf from caudal fin of endangered yellow catfish, horabagrus brachysoma (gunther, 1864).a new epithelial cell line, horabagrus brachysoma fin (hbf), was established from the caudal fin tissue of yellow catfish, h. brachysoma and characterized. this hbf cell line was maintained in leibovitz's-15 medium supplemented with 15 % fetal bovine serum (fbs) and subcultured more than 62 times over a period of 20 months. the hbf cell line consists predominantly of epithelial cells and is able to grow at temperatures between 20 and 35 °c with an optimum temperature of 28 °c. the growth rate of ...201625359669
detection of virulence genes in environmental strains of vibrio cholerae from estuaries in northeastern brazil.the objectives of this study were to detect the presence of vibrio cholerae in tropical estuaries (northeastern brazil) and to search for virulence factors in the environmental isolates. water and sediment samples were inoculated onto a vibrio-selective medium (tcbs), and colonies with morphological resemblance to v. cholerae were isolated. the cultures were identified phenotypically using a dichotomous key based on biochemical characteristics. the total dna extracted was amplified by pcr to det ...201725229224
survival, induction and resuscitation of vibrio cholerae from the viable but non-culturable state in the southern caribbean sea.the causative agent of cholera, vibrio cholerae, can enter into a viable but non-culturable (vbnc) state in response to unfavorable conditions. the aim of this study was to evaluate the in situ survival of v. cholerae in an aquatic environment of the southern caribbean sea, and its induction and resuscitation from the vbnc state. v. cholerae non-o1, non-o139 was inoculated into diffusion chambers placed at the cuare wildlife refuge, venezuela, and monitored for plate, total and viable cells coun ...201725651322
the vibrio cholerae toxr regulon encodes host-specific chemotaxis proteins that function in intestinal colonization.virulence gene regulation in vibrio cholerae is under the control of the toxr-toxt regulatory cascade. chemotaxis and net motility have been shown to influence the infectivity of vibrio cholerae. v. cholerae toxr mutants do not synthesize proteins required for chemotaxis towards mucus. the inability of the toxr mutant strain to recognize and swim towards mucus is due to their failure to synthesize acfb, a methyl-accepting chemotaxis protein. acfb has previously been shown to be involved in intes ...201727213179
comparative genome analysis of non-toxigenic non-o1 versus toxigenic o1 vibrio cholerae.pathogenic strains of vibrio cholerae are responsible for endemic and pandemic outbreaks of the disease cholera. the complete toxigenic mechanisms underlying virulence in vibrio strains are poorly understood. the hypothesis of this work was that virulent versus non-virulent strains of v. cholerae harbor distinctive genomic elements that encode virulence. the purpose of this study was to elucidate genomic differences between the o1 serotypes and non-o1 v. cholerae ps15, a non-toxigenic strain, in ...201725722857
typing and antibiogram of vibrio cholerae isolates from a tertiary care hospital in pune: a 3 year study.a retrospective analysis was done over a period of 3 years (january 2010- december 2012) in a tertiary care hospital, pune, to note the changes in the prevalence and distribution of biotypes, serotypes, antibiotic susceptibility pattern and phage types of vibrio cholerae isolates from clinical samples so as to be vigilant and curtail major outbreak in future. vibrio cholerae isolates were obtained from 4.4% of the 1126 fecal specimens processed from cases of acute watery diarrhea. majority of th ...201725722619
efficient responses to host and bacterial signals during vibrio cholerae colonization.vibrio cholerae, the microorganism responsible for the diarrheal disease cholera, is able to sense and respond to a variety of changing stimuli in both its aquatic and human gastrointestinal environments. here we present a review of research efforts aimed toward understanding the signals this organism senses in the human host. v. cholerae's ability to sense and respond to temperature and ph, bile, osmolarity, oxygen and catabolite levels, nitric oxide, and mucus, as well as the quorum sensing si ...201724256715
cholera outbreaks in urban bangladesh in 2011.in 2011, a multidisciplinary team investigated two diarrhoea outbreaks affecting urban bangladeshi communities from the districts of bogra and kishorganj to identify etiology, pathways of transmission, and factors contributing to these outbreaks.201726702366
great cormorants (phalacrocorax carbo) as potential vectors for the dispersal of vibrio cholerae.vibrio cholerae is the cause of cholera, a devastating epidemic and pandemic disease. despite its importance, the way of its global dissemination is unknown. v. cholerae is abundant in aquatic habitats and is known to be borne by copepods, chironomids and fishes. our aim was to determine if fish-eating birds act as vectors in the spread of v. cholerae by consuming infected fish. we determined the existence of v. cholerae in the microbiome of 5/7 wild cormorants' intestine. in three of these v. c ...201728801549
enhancing multiplex genome editing by natural transformation (mugent) via inactivation of ssdna exonucleases.recently, we described a method for multiplex genome editing by natural transformation (mugent). mutant constructs for mugent require large arms of homology (>2000 bp) surrounding each genome edit, which necessitates laborious in vitro dna splicing. in vibrio cholerae, we uncover that this requirement is due to cytoplasmic ssdna exonucleases, which inhibit natural transformation. in ssdna exonuclease mutants, one arm of homology can be reduced to as little as 40 bp while still promoting integrat ...201728575400
detection of eight foodborne bacterial pathogens by oligonucleotide array hybridization.simultaneous and rapid detection of multiple foodborne bacterial pathogens is important for the prevention of foodborne illnesses.201728713514
development of a novel rationally designed antibiotic to inhibit a nontraditional bacterial target.the search for new nontraditional targets is a high priority in antibiotic design today. bacterial membrane energetics based on sodium ion circulation offers potential alternative targets. the present work identifies the na(+)-translocating nadh:ubiquinone oxidoreductase (na(+)-nqr), a key respiratory enzyme in many microbial pathogens, as indispensible for the chlamydia trachomatis infectious process. infection by chlamydia trachomatis significantly increased first h(+) and then na(+) levels wi ...201728425301
use of serologic responses against enteropathogens to assess the impact of a point-of-use water filter: a randomized controlled trial in western province, rwanda.diarrhea is a leading contributor to childhood morbidity and mortality in sub-saharan africa. given the challenge of blinding most water, sanitation, and hygiene (wash) interventions, diarrheal disease outcome measures in wash intervention trials are subject to potential bias and misclassification. using the platform of a cluster-randomized controlled trial of a household-based drinking water filter in western province, rwanda, we assessed the impact of the drinking water filter on enteric seroc ...201728749764
correlation of edge truncation with antibacterial activity of plate-like anisotropic silver nanoparticles.the effect of silver nanoparticle anisotropy on the antibacterial properties has been studied against escherichia coli, staphylococcus aureus, bacillus, vibrio cholerae, and streptococcus pyogenes. anisotropic silver nanoparticles have been synthesized by solvothermal process. the uv-visible absorption, x-ray diffraction, and tem studies show the anisotropic nature of silver nanoparticles. the results demonstrate that the anisotropic silver nanoparticles undergo a shape-dependent interaction wit ...201728707245
characterization of the escherichia coli concentrative nucleoside transporter nupc using computational, biochemical, and biophysical methods.members of the concentrative nucleoside transporter (cnt) family of proteins mediate uptake of nucleosides into cells driven by a cation gradient, which then enter salvage pathways for nucleic acid synthesis. in humans, they also transport hydrophilic anticancer and antiviral nucleoside analogue drugs into cells and tissues where they exert their pharmacological effects. escherichia coli cnt nupc (400 residues) is pyrimidine-specific and driven by a proton gradient. we have used computational, b ...201728682624
putative protein vc0395_0300 from vibrio cholerae is a diguanylate cyclase with a role in biofilm formation.the hallmark of the lifecycle of vibrio cholerae is its ability to switch between two lifestyles - the sessile, non-pathogenic form and the motile, infectious form in human hosts. one of these changes is in the formation of surface biofilms, when in sessile aquatic habitats. the cell-cell interactions within a v. cholerae biofilm are stabilized by the production of an exopolysachharide (eps) matrix, which in turn is regulated by the ubiquitous secondary messenger, cyclic di-gmp (c-di-gmp), synth ...201728647124
electrostatic interactions between the ctx phage minor coat protein and the bacterial host receptor tola drive the pathogenic conversion of vibrio cholerae.vibrio cholerae is a natural inhabitant of aquatic environments and converts to a pathogen upon infection by a filamentous phage, ctxφ, that transmits the cholera toxin-encoding genes. this toxigenic conversion of v. cholerae has evident implication in both genome plasticity and epidemic risk, but the early stages of the infection have not been thoroughly studied. ctxφ transit across the bacterial periplasm requires binding between the minor coat protein named piii and a bacterial inner-membrane ...201728642371
a versatile toolbox for the control of protein levels using n(ε)-acetyl-l-lysine dependent amber suppression.the analysis of the function of essential genes in vivo depends on the ability to experimentally modulate levels of their protein products. current methods to address this are based on transcriptional or post-transcriptional regulation of mrnas, but approaches based on the exploitation of translation regulation have so far been neglected. here we describe a toolbox, based on amber suppression in the presence of n(ε)-acetyl-l-lysine (ack), for translational tuning of protein output. we chose the ...201728594177
evaluation of synergy and bacterial regrowth in photocatalytic ozonation disinfection of municipal wastewater.the use of solar and ultraviolet titanium dioxide photocatalytic ozonation processes to inactivate waterborne pathogens (escherichia coli, salmonella species, shigella species and vibrio cholerae) in synthetic water and secondary municipal wastewater effluent is presented. the performance indicators were bacterial inactivation efficiency, post-disinfection regrowth and synergy effects (collaboration) between ozonation and photocatalysis (photocatalytic ozonation). photocatalytic ozonation effect ...201728577398
histo-blood group antigens as mediators of infections.the critical first step of a microbial infection is usually the attachment of pathogens to host cell glycans. targets on host tissues are in particular the histo-blood group antigens (hbgas), which are present in rich diversity in the mucus layer and on the underlying mucosa. recent structural and functional studies have revealed significant new insight into the molecular mechanisms, explaining why individuals with certain blood groups are at increased risk of some infections. the most prominent ...201728544984
structural studies of the periplasmic portion of the diguanylate cyclase cdgh from vibrio cholerae.cyclic diguanylate monophosphate (c-di-gmp) is a second messenger involved in bacterial signal transduction and produced by diguanylate cyclases (dgcs) generally containing highly variable periplasmic signal-recognition domains. cdgh is a dgc enzyme that regulates rugosity associated phenotypes in vibrio cholerae. cdgh has two n-terminal tandem periplasmic substrate-binding (pbpb) domains for its signal recognition; however, the role of the tandem pbpb domains remains unclear. here, we reported ...201728500346
rstb regulates expression of the photobacterium damselae subsp. damselae major virulence factors damselysin, phobalysin p and phobalysin c.the marine pathogenic bacterium photobacterium damselae subsp. damselae causes septicemia in marine animals and in humans. the pphdd1 plasmid-encoded hemolysins damselysin (dly) and phobalysin p (phlyp), and the chromosome-encoded hemolysin phobalysin c (phlyc) constitute its main virulence factors. however, the mechanisms by which expression of these three hemolysins is regulated remain unknown. here we report the isolation of a mini-tn10 transposon mutant which showed a strong impairment in it ...201728443076
repurposing a two-component system-based biosensor for the killing of vibrio cholerae.new strategies to control cholera are urgently needed. this study develops an in vitro proof-of-concept sense-and-kill system in a wild-type escherichia coli strain to target the causative pathogen vibrio cholerae using a synthetic biology approach. our engineered e. coli specifically detects v. cholerae via its quorum-sensing molecule cai-1 and responds by expressing the lysis protein yebf-art-085, thereby self-lysing to release the killing protein art-085 to kill v. cholerae. for this report, ...201728441472
antibacterial and antioxidant constituents of extracts of endophytic fungi isolated from ocimum basilicum var. thyrsiflora leaves.fourteen fungal endophytes were isolated from the ocimum basilicum var. thyrsiflora leaves collected from northern thailand. eight genera were identified including aspergillus, ascochyta, nigrospora, blastomyces, colletotrichum, exidia, clitopilus, and nomuraea. the antibacterial activity of crude extracts from all endophytic fungi was tested against nine human bacterial pathogens: staphylococcus aureus, staphylococcus epidermidis, bacillus subtilis, bacillus cereus, escherichia coli, klebsiella ...201728698913
identification and growth optimization of a marine bacillus dk1-sa11 having potential of producing broad spectrum antimicrobial compounds.control of harmful bacteria in food, aquaculture, pharmaceuticals, agriculture, hospitals and recreation water pools are of great global concern. marine bacteria are an enormous source of bio-controlling agents. the aim of this study was to identify and optimize the growth conditions including effect of different biotic and abiotic factors on antimicrobial activity of strain dk1-sa11 isolated from qingdao bay of china yellow sea. microscopic characterization, api® 20e and 50 chb kit base carbohy ...201728653930
prevalence of enteric infections among hospitalized patients in two referral hospitals in ghana.diarrhea is an important cause of morbidity and mortality worldwide. in africa and ghana in particular, it is estimated to contribute directly to 19 and 25% of pediatric mortality among children under 5 years, respectively.201728716138
antiprotozoal, antibacterial and antidiarrheal properties from the flowers of chiranthodendron pentadactylon and isolated flavonoids.chiranthodendron pentadactylon larreat. (sterculiaceae) is a mexican plant used in traditional medicine for the treatment of heart disease symptoms and infectious diarrhea.201728539715
plant-made virus-like particles bearing influenza hemagglutinin (ha) recapitulate early interactions of native influenza virions with human monocytes/macrophages.plant-made virus-like particles (vlp) bearing influenza virus hemagglutinins (ha) are novel vaccine candidates that induce cross-reactive humoral and poly-functional t cell responses. to better understand the mechanisms that underlie this broad immunogenicity we studied early interactions of vlps bearing either h1 (a/california/07/2009 (h1n1)) or h5 (a/indonesia/05/2005 (h5n1)) with a human monocytoid cell line (u-937 cells) and human monocyte-derived macrophages (mdms) as model antigen-presenti ...201728712489
heme proximal hydrogen bonding between his170 and asp132 plays an essential role in the heme degradation reaction of hutz from vibrio cholerae.hutz from vibrio cholerae is an enzyme that catalyzes the oxygen-dependent degradation of heme. the crystal structure of the homologous protein from helicobacter pylori, hugz, predicts that asp132 in hutz is located within hydrogen-bonding distance of the heme axial ligand his170. hydrogen bonding between his170 and asp132 appears to be disfavored in heme-degrading enzymes, because it can contribute to the imidazolate character of the axial histidine, as observed in most heme-containing peroxida ...201728481076
discovery of two bacterial nitric oxide-responsive proteins and their roles in bacterial biofilm regulation.bacterial biofilms form when bacteria adhere to a surface and produce an exopolysaccharide matrix ( costerton science 1999 , 284 , 1318 ; davies science 1998 , 280 , 295 ; flemming nat. rev. microbiol. 2010 , 8 , 623 ). because biofilms are resistant to antibiotics, they are problematic in many aspects of human health and welfare, causing, for instance, persistent fouling of medical implants such as catheters and artificial joints ( brunetto chimia 2008 , 62 , 249 ). they are responsible for chr ...201728605194
a novel role of listeria monocytogenes membrane vesicles in inhibition of autophagy and cell death.bacterial membrane vesicle (mv) production has been mainly studied in gram-negative species. in this study, we show that listeria monocytogenes, a gram-positive pathogen that causes the food-borne illness listeriosis, produces mvs both in vitro and in vivo. we found that a major virulence factor, the pore-forming hemolysin listeriolysin o (llo), is tightly associated with the mvs, where it resides in an oxidized, inactive state. previous studies have shown that llo may induce cell death and auto ...201728516064
the dnak chaperone uses different mechanisms to promote and inhibit replication of vibrio cholerae chromosome 2.replication of vibrio cholerae chromosome 2 (chr2) depends on molecular chaperone dnak to facilitate binding of the initiator (rctb) to the replication origin. the binding occurs at two kinds of site, 12-mers and 39-mers, which promote and inhibit replication, respectively. here we show that dnak employs different mechanisms to enhance the two kinds of binding. we found that mutations in rctb that reduce dnak binding also reduce 12-mer binding and initiation. the initiation defect is suppressed ...201728420739
regulation of acetyl-coa synthetase transcription by the crbs/r two-component system is conserved in genetically diverse environmental pathogens.the crbs/r two-component signal transduction system is a conserved regulatory mechanism through which specific gram-negative bacteria control acetate flux into primary metabolic pathways. crbs/r governs expression of acetyl-coa synthase (acsa), an enzyme that converts acetate to acetyl-coa, a metabolite at the nexus of the cell's most important energy-harvesting and biosynthetic reactions. during infection, bacteria can utilize this system to hijack host acetate metabolism and alter the course o ...201728542616
vibrio cholerae type 6 secretion system effector trafficking in target bacterial cells.the type 6 secretion system (t6ss) is used by many gram-negative bacterial species to deliver toxic effector proteins into nearby bacteria prey cells to kill or inhibit their growth. vgrg proteins are core conserved secretion substrates of the t6ss and one subset of t6ss effectors consists of vgrg proteins with c-terminal extension domains carrying various enzymatic activities. in vibrio cholerae, vgrg3 has a hydrolase extension domain and degrades peptidoglycan in the periplasm of target bacter ...201728808000
control of virulence gene transcription by indirect readout in vibrio cholerae and salmonella enterica serovar typhimurium.indirect readout mechanisms of transcription control rely on the recognition of dna shape by transcription factors (tfs). tfs may also employ a direct readout mechanism that involves the reading of the base sequence in the dna major groove at the binding site. tfs with winged helix-turn-helix (whth) motifs use an alpha helix to read the base sequence in the major groove while inserting a beta sheet 'wing' into the adjacent minor groove. such whth proteins are important regulators of virulence ge ...201728631437
evaluation of microplate immunocapture method for detection of vibrio cholerae, salmonella typhi and shigella flexneri from food.improved methods with better separation and concentration ability for detection of foodborne pathogens are in constant need. the aim of this study was to evaluate microplate immunocapture (ic) method for detection of salmonella typhi, shigella flexneri and vibrio cholerae from food samples to provide a better alternative to conventional culture based methods.201728851288
crystal structure of master biofilm regulator csgd regulatory domain reveals an atypical receiver domain.the master regulator csgd switches planktonic growth to biofilm formation by activating synthesis of curli fimbriae and cellulose in enterobacteriaceae. csgd was classified to be the luxr response regulatory family, while its cognate sensor histidine kinase has not been identified yet. csgd consists of a c-terminal dna binding domain and an n-terminal regulatory domain that provokes the upstream signal transduction to further modulate its function. we provide the crystal structure of salmonella ...201728758290
interbacterial predation as a strategy for dna acquisition in naturally competent bacteria.natural competence enables bacteria to take up exogenous dna. the evolutionary function of natural competence remains controversial, as imported dna can act as a source of substrates or can be integrated into the genome. exogenous homologous dna can also be used for genome repair. in this opinion article, we propose that predation of non-related neighbouring bacteria coupled with competence regulation might function as an active strategy for dna acquisition. competence-dependent kin-discriminate ...201728690319
environmental vibrios represent a source of antagonistic compounds that inhibit pathogenic vibrio cholerae and vibrio parahaemolyticus strains.with the overuse of antibiotics, many pathogens including vibrio cholerae and vibrio parahaemolyticus have evolved multidrug resistance making treatment more difficult. while understanding the mechanisms that underlie pathogenesis is crucial, knowledge of bacterial interactions of v. cholerae and v. parahaemolyticus could provide insight to their susceptibility outside of the human host. based on previous work showing competition among environmental strains, we predict that marine-derived bacter ...201728857444
modelling of growth kinetics of vibrio cholerae in presence of gold nanoparticles: effect of size and morphology.emergence of multiple drug resistant strains of pathogenic bacteria calls for new initiatives to combat infectious diseases. gold nanoparticles (aunps), because of their non-toxic nature and size/shape dependent optical properties, offer interesting possibility. here we report the antibacterial efficacy of aunps of different size and shape (auns10, auns100 and aunr10; the number indicating the diameter in nm; s stands for sphere and r for rod) against the classical (o395) and el tor (n16961) bio ...201728851910
transposon insertion site sequencing for synthetic lethal screening.transposon insertion site sequencing (tis) permits genome-wide, quantitative fitness assessment of individual genomic loci. in addition to the identification of essential genes in given growth conditions, tis enables the elucidation of genetic networks such as synthetic lethal or suppressor gene combinations. therefore, tis becomes an exceptionally powerful tool for the high-throughput determination of genotype-phenotype relationships in bacteria. here, we describe a protocol for the generation ...201728842874
highlights from this issue. 201728839876
extracellular-matrix-mediated osmotic pressure drives vibrio cholerae biofilm expansion and cheater exclusion.biofilms, surface-attached communities of bacteria encased in an extracellular matrix, are a major mode of bacterial life. how the material properties of the matrix contribute to biofilm growth and robustness is largely unexplored, in particular in response to environmental perturbations such as changes in osmotic pressure. here, using vibrio cholerae as our model organism, we show that during active cell growth, matrix production enables biofilm-dwelling bacterial cells to establish an osmotic ...201728835649
prediction of bacterial small rnas in the rsma (csra) and toxt pathways: a machine learning approach.small rnas (srnas) constitute an important class of post-transcriptional regulators that control critical cellular processes in bacteria. recent research using high-throughput transcriptomic approaches has led to a dramatic increase in the discovery of bacterial srnas. however, it is generally believed that the currently identified srnas constitute a limited subset of the bacterial srna repertoire. in several cases, srnas belonging to a specific class are already known and the challenge is to id ...201728830349
spermine inhibits vibrio cholerae biofilm formation through the nsps-mbaa polyamine signaling system.the aquatic bacterium and human intestinal pathogen, vibrio cholerae, senses and responds to a variety of environment-specific cues to regulate biofilm formation. specifically, the polyamines norspermidine and spermidine enhance and repress v. cholerae biofilm formation, respectively. these effects are relevant for understanding v. cholerae pathogenicity and are mediated through the periplasmic binding protein, nsps, and the transmembrane c-di-gmp phosphodiesterase mbaa. however, the levels of s ...201728827313
from hospitalization records to surveillance: the use of local patient profiles to characterize cholera in vellore, india.despite availability of high quality medical records, health care systems often do not have the resources or tools to utilize these data efficiently. yet, hospital-based, laboratory-confirmed records may pave the way for building reliable surveillance systems capable of monitoring temporal trends of emerging infections. in this communication, we present a new tool to compress and visualize medical records with a local population profile (lpp) approach, which transforms information into statistic ...201728820902
molecular epidemiology of cholera outbreaks during the rainy season in mandalay, myanmar.cholera, caused by vibrio cholerae, remains a global threat to public health. in myanmar, the availability of published information on the occurrence of the disease is scarce. we report here that cholera incidence in mandalay generally exhibited a single annual peak, with an annual average of 312 patients with severe dehydration over the past 5 years (since 2011) and was closely associated with the rainy season. we analyzed cholera outbreaks, characterized 67 isolates of v. cholerae serogroup o1 ...201728820711
large cholera outbreak in brong ahafo region, ghana.a nationwide outbreak of vibrio cholerae occurred in ghana in 2014 with accra, the nation's capital as the epi-center. the outbreak spread to the brong ahafo region (bar) which is geographically located in the middle of the country. in this region a review of data collected during the outbreak was carried out and analyzed descriptively to determine the hot spots and make recommendations for effective response to future outbreaks.201728797285
rational design of artificial dye-decolorizing peroxidases using myoglobin by engineering tyr/trp in the heme center.the rational design of metalloenzymes provides advantages not only for illustrating the structure and function relationship of native enzymes, but also for creating functional artificial enzymes comparable to native enzymes. dye-decolorizing peroxidases (dyps) are a new family of heme peroxidases and have received much attention recently. inspired by the structural features of native dyps with multiple tyr and trp residues, we herein aimed to design functional artificial dyps using myoglobin (mb ...201728795725
antibiotics resistance in el tor vibrio cholerae 01 isolated during cholera outbreaks in mozambique from 2012 to 2015.mozambique has recorded cyclically epidemic outbreaks of cholera. antibiotic therapy is recommended in specific situations for management and control of cholera outbreaks. however, an increase in resistance rates to antibiotics by vibrio cholerae has been reported in several epidemic outbreaks worldwide. on the other hand, there are few recent records of continuous surveillance of antibiotics susceptibility pattern of v. cholerae in mozambique.201728792540
murb as a target in an alternative approach to tackle the vibrio cholerae resistance using molecular docking and simulation study.cholera is a serious threat to a large population in the under developed countries. though oral rehydration therapy is the preferred choice of treatment, the use of antibiotics could reduce the microbial load in the case of severity. the use of antibiotics is also sought in the scenarios where there is problem with access to clean water. however, vibrio cholera strains have developed resistance to antibiotics such as amoxicillin, ampicillin, chloramphenicol, doxycycline, erythromycin and tetracy ...201728786497
selection of affinity peptides for interference-free detection of cholera toxin.cholera toxin is a major virulent agent of vibrio cholerae, and it can rapidly lead to severe dehydration, shock, causing death within hours without appropriate clinical treatments. in this study, we present a method wherein unique and short peptides that bind to cholera toxin subunit b (ctx-b) were selected through m13 phage display. biopanning over recombinant ctx-b led to rapid screening of a unique peptide with an amino acid sequence of vqcrlgppwcak, and the phage-displayed peptides analyzed ...201728780344
ultrasensitive biosensor for the detection of vibrio cholerae dna with polystyrene-co-acrylic acid composite nanospheres.an ultrasensitive electrochemical biosensor for the determination of pathogenic vibrio cholerae (v. cholerae) dna was developed based on polystyrene-co-acrylic acid (psa) latex nanospheres-gold nanoparticles composite (psa-aunps) dna carrier matrix. differential pulse voltammetry (dpv) using an electroactive anthraquninone oligonucleotide label was used for measuring the biosensor response. loading of gold nanoparticles (aunps) on the dna-latex particle electrode has significantly amplified the ...201728774152
structural dynamics of rbma governs plasticity of vibrio cholerae biofilms.biofilm formation is critical for the infection cycle of vibrio cholerae. vibrio exopolysaccharides (vps) and the matrix proteins rbma, bap1 and rbmc are required for the development of biofilm architecture. we demonstrate that rbma binds vps directly and uses a binary structural switch within its first fibronectin type iii (fniii-1) domain to control rbma structural dynamics and the formation of vps-dependent higher-order structures. the structural switch in fniii-1 regulates interactions in tr ...201728762945
low doses of cholera toxin and its mediator camp induce ctla-2 secretion by dendritic cells to enhance regulatory t cell conversion.immature or semi-mature dendritic cells (dcs) represent tolerogenic maturation stages that can convert naive t cells into foxp3+ induced regulatory t cells (itreg). here we found that murine bone marrow-derived dcs (bm-dcs) treated with cholera toxin (ct) matured by up-regulating mhc-ii and costimulatory molecules using either high or low doses of ct (cthi, ctlo) or with camp, a known mediator ct signals. however, all three conditions also induced mrna of both isoforms of the tolerogenic molecul ...201728759565
systematic genetic dissection of chitin degradation and uptake in vibrio cholerae.vibrio cholerae is a natural resident of the aquatic environment, where a common nutrient is the chitinous exoskeletons of microscopic crustaceans. chitin utilization requires chitinases, which degrade this insoluble polymer into soluble chitin oligosaccharides. these oligosaccharides also serve as an inducing cue for natural transformation in vibrio species. there are 7 predicted endochitinase-like genes in the v. cholerae genome. here, we systematically dissect the contribution of each gene to ...201728752963
transmission dynamics of cholera in yemen, 2017: a real time forecasting.a large epidemic of cholera, caused by vibrio cholerae, serotype ogawa, has been ongoing in yemen, 2017. to improve the situation awareness, the present study aimed to forecast the cholera epidemic, explicitly addressing the reporting delay and ascertainment bias.201728747188
horizontal gene transfer of functional type vi killing genes by natural transformation.horizontal gene transfer (hgt) can have profound effects on bacterial evolution by allowing individuals to rapidly acquire adaptive traits that shape their strategies for competition. one strategy for intermicrobial antagonism often used by proteobacteria is the genetically encoded contact-dependent type vi secretion system (t6ss), a weapon used to kill heteroclonal neighbors by direct injection of toxic effectors. here, we experimentally demonstrate that vibrio cholerae can acquire new t6ss eff ...201728743812
growth arrest and a persister state enable resistance to osmotic shock and facilitate dissemination of vibrio cholerae.vibrio cholerae is a water-borne bacterial pathogen and causative agent of cholera. although v. cholerae is a halophile, it can survive in fresh water, and this has a major role in cholera epidemics through consumption of contaminated water and subsequent fecal-oral spread. after dissemination from humans back into fresh water, v. cholerae encounters limited nutrient availability and an abrupt drop in conductivity but little is known about how v. cholerae adapts to, and survives in this environm ...201728742070
household and individual risk factors for cholera among cholera vaccine recipients in rural haiti.oral cholera vaccination was used as part of cholera control in haiti, but the vaccine does not provide complete protection. we conducted secondary data analyses of a vaccine effectiveness study in haiti to evaluate risk factors for cholera among cholera vaccine recipients. individuals vaccinated against cholera that presented with acute watery diarrhea and had a stool sample positive for vibrio cholerae o1 were included as cases. up to four vaccinated individuals who did not present for treatme ...201728722575
a prolonged, community-wide cholera outbreak associated with drinking water contaminated by sewage in kasese district, western uganda.in may 2015, a cholera outbreak that had lasted 3 months and infected over 100 people was reported in kasese district, uganda, where multiple cholera outbreaks had occurred previously. we conducted an investigation to identify the mode of transmission to guide control measures.201728720083
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