studies on the occurrence of gram-negative bacteria in ticks: ixodes ricinus as a potential vector of pasteurella.a total of 372 ixodes ricinus ticks (101 females, 122 males, and 149 nymphs) collected by flagging in 6 mixed woodlands of eastern poland were examined by culture for the presence of internal gram-negative bacteria other than borrelia burgdorferi. adult ticks were examined in pools of 2 specimens each and nymphs were examined in pools of 3-5 specimens each. ticks were disinfected in 70 % ethanol and homogenized in 0.85% nacl. the diluted homogenate was inoculated onto 3 kinds of agar media: buff ...200415627343
antibacterial constituents from the berries of piper nigrum.piper nigrum finds an extensive application in antibacterial preparations belonging to ayurvedic system of medicine. a bioguided extraction and fractionation of the petroleum ether extract of the berries of p. nigrum afforded 2e, 4e, 8z-n-isobutyleicosatrienamide (1), pellitorine (2), trachyone (3), pergumidiene (4) and isopiperolein b (5). pergumidiene and trachyone are isolated for the first time from p. nigrum. all the isolated compounds were active against bacillus subtilis, bacillus sphaeri ...200415636188
chromobacterium violaceum septicaemia from north india.though chromobacterium violaceum is a common inhabitant of soil and water in tropical and sub-tropical regions, human infections are rare but when they do occur result in high mortality. since the first case from malaysia in 1927, about 150 cases have been reported in world literature. till date 6 cases have been reported from southern and eastern parts of india. we report here a case of c. violaceum septicaemia, probably the first case from north india. the patient, a 6 and a half year old boy ...200415654137
the flag-2 locus, an ancestral gene cluster, is potentially associated with a novel flagellar system from escherichia coli.escherichia coli k-12 possesses two adjacent, divergent, promoterless flagellar genes, fhia-mbha, that are absent from salmonella enterica. through bioinformatics analysis, we found that these genes are remnants of an ancestral 44-gene cluster and are capable of encoding a novel flagellar system, flag-2. in enteroaggregative e. coli strain 042, there is a frameshift in lfgc that is likely to have inactivated the system in this strain. tiling path pcr studies showed that the flag-2 cluster is pre ...200515687208
effect of temperature, ph, and metals on the stability and activity of phenylalanine hydroxylase from chromobacterium violaceum.phenylalanine hydroxylase (pah) is a non-heme iron dioxygenase catalyzing the conversion of phenylalanine to tyrosine and is present in both prokaryotic and eukaryotic organisms. a relatively simple pah is expressed by chromobacterium violaceum, a gram-negative bacterium found in tropical and subtropical regions. the effects of temperature, ph and metals on the stability and catalytic activity of chromobacterium violaceum pah were determined by steady-state kinetics, circular dichroism (cd) and ...200515708798
enzyme hyperactivity in aot water-in-oil microemulsions is induced by 'lone' sodium counterions in the water-pool.water-in-oil microemulsions are thermodynamically stable single-phase dispersions of water and surfactant within a continuous oil phase. the classical ternary system, based on the surfactant sodium bis(2-ethylhexyl)sulfosuccinate ('aot'), water and an alkane such as n-heptane, is an optically transparent monodispersion of spherical water-droplets coated with a close-packed surfactant monolayer and the droplet radius is, to a good first approximation, directly proportional to the molar water: sur ...200515715311
genotyping of chromobacterium violaceum isolates by reca pcr-rflp analysis.intraspecies variation of chromobacterium violaceum was examined by comparative sequence - and by restriction fragment length polymorphism analysis of the recombinase a gene (reca-pcr-rflp). primers deduced from the known reca gene sequence of the type strain c. violaceum atcc 12472(t) allowed the specific amplification of a 1040bp reca fragment from each of the 13 c. violaceum strains investigated, whereas other closely related organisms tested negative. hindii-psti-reca rflp analysis generated ...200515766789
a very rare and rapidly fatal case of chromobacterium violaceum septicemia.chromobacterium violaceum infection is rare but causes a high mortality rate particularly in immunosuppressed persons. since its clinical presentation is non-specific and the diagnosis basically relies upon blood culture and sensitivity, this infection should be considered among the organisms targeted empirically for antibiotic therapy when a cellulitis or rapidly progressive illness follows exposure to water or soil. this is a case of fulminant septicemia caused by this rarely encountered organ ...200415779589
cloning and sequencing of a genomic island found in the brazilian purpuric fever clone of haemophilus influenzae biogroup aegyptius.a genomic island was identified in the haemophilus influenzae biogroup aegyptius brazilian purpuric fever (bpf) strain f3031. this island, which was also found in other bpf isolates, could not be detected in non-bpf biogroup aegyptius strains or in nontypeable or typeable h. influenzae strains, with the exception of a region present in the type b eagan strain. this 34,378-bp island is inserted, in reference to h. influenzae rd kw20, within a choline transport gene and contains a mosaic structure ...200515784532
quorum sensing in halophilic bacteria: detection of n-acyl-homoserine lactones in the exopolysaccharide-producing species of halomonas.some members of the moderately halophilic genus halomonas, such as h. eurihalina, h. maura, h. ventosae and h. anticariensis, produce exopolysaccharides with applications in many industrial fields. we report here that these four species also produce autoinducer molecules that are involved in the cell-to-cell signaling process known as quorum sensing. by using the n-acyl homoserine lactone (ahl) indicator strains agrobacterium tumefaciens ntl4 (pzrl4) and chromobacterium violaceum cv026, we disco ...200515909077
invasive chromobacterium violaceum infection in children: case report and review.a 3.3-year-old boy developed chromobacterium violaceum abscesses of lungs, liver and spleen and was successfully treated. he had chronic granulomatous disease (cgd). twenty-five episodes of invasive c. violaceum infection in 24 children were reviewed. all 9 cgd and 10 nonbacteremic cases survived, but 12 of 16 (75%) non-cgd and 12 of 15 (80%) bacteremic patients died.200515933571
genetic characterization of chromobacterium isolates from black water environments in the brazilian isolate and to characterize the diversity of chromobacterium violaceum from the brazilian amazon region.200515960747
head-group size or hydrophilicity of surfactants: the major regulator of lipase activity in cationic water-in-oil determine the crucial role of surfactant head-group size in micellar enzymology, the activity of chromobacterium viscosum (cv) lipase was estimated in cationic water-in-oil (w/o) microemulsions of three different series of surfactants with varied head-group size and hydrophilicity. the different series were prepared by subsequent replacement of three methyl groups of cetyltrimethylammonium bromide (ctab) with hydroxyethyl (1-3, series i), methoxyethyl (4-6, series ii), and n-propyl (7-9, seri ...200515977280
self-assembly of precursors in single-crystal growth of biopolymers.self-assembly of precursors in dilute solution single-crystal growth of poly[(r)-3-hydroxyvalerate] (phv) and the fungal polysaccharide mycodextran were studied by transmission electron microscopy, especially at the early stages of crystallization. precursors for phv, such as small primary nuclei and tiny square tiles, consolidate to a large square crystal composed of orthogonally arranged tiles. by contrast, the precursors of mycodextran were lath-shaped, which suggests that the crystal growth ...200516004471
quorum sensing signal molecules (acylated homoserine lactones) in gram-negative fish pathogenic bacteria.the aim of the present study was to investigate the production of quorum sensing signals (specifically acylated homoserine lactones, ahls) among a selection of strains of gram-negative fish bacterial pathogens. these signals are involved in the regulation of virulence factors in some human and plant-pathogenic bacteria. a total of 59 strains, representing 9 different fish pathogenic species, were tested against 2 ahl monitor bacteria (agrobacterium tumefaciens nt1 [pzlr4] and chromobacterium vio ...200516042042
surfactant tail length-dependent lipase activity profile in cationic water-in-oil microemulsions.the catalytic activity of chromobacterium viscosum lipase (cv-lipase) was estimated across varying surfactant tail lengths (c-10-c-18) in water-in-oil (w/o) microemulsions of cationic surfactants containing four different hydroxyethyl-substituted head groups. an attempt to find a correlation, if any, between the activity of interfacially solubilized lipase and the varying surfactant tails was made for the first time in micellar enzymology. the second-order rate constant, k2, in lipase-catalyzed ...200516112238
stable transformation of chromobacterium violaceum with a broad-host-range plasmid.stable transformants of chromobacterium violaceum were obtained by high-voltage electroporation with a 7-kilobase binary plasmid. the technique was reliable, reproducible, and simple, with efficiencies of 10(5) transformants/microg of plasmid dna. the electrical conditions that resulted in the highest efficiencies were short pulse length (4.4-4.5 ms) and high voltage (12.5 kv/cm). the numbers of transformants were almost the same during the growth exponential phase (variation at optical density) ...200616172890
contrasting occurrence of chromobacterium violaceum in tropical drinking water springs of uganda.occurrence of chromobacterium violaceum in six protected drinking water springs in uganda was investigated. c. violaceum showed a contrasting occurrence, which was independent of human impact as assessed by faecal pollution indicators. it was isolated from two springs (s1 and s2) that were located close to each other (3 km) but not in the rest. in s1 c. violaceum was continuously detected, in concentrations ranging from 6 to 270 cfu 100 ml(-1), while in s2 it was detected on only one sampling oc ...200516209027
chromobacterium violaceum in siblings, brazil.chromobacterium violaceum, a saprophyte bacterium found commonly in soil and water in tropical and subtropical climates, is a rare cause of severe, often fatal, human disease. we report 1 confirmed and 2 suspected cases of c. violaceum septicemia, with 2 fatalities, in siblings after recreational exposure in northeastern brazil.200516229777
effect of hydrocarbon-water interfaces on synthetic and hydrolytic activities of lipases.we have developed a new method of lipase activation for interesterification, in which lipase, in contact with a hydrocarbon-water interface, has been found to have high interesterification activity in an anhydrous solvent. we have applied this activation method to various lipase and obtained high synthetic activity in n-hexane, and have investigated the effect of various hydrocarbon-water interfaces on the synthetic and hydrolytic activities of lipases. the esterification and/or interesterificat ...200116233091
n-butanoyl-l-homoserine lactone (bhl) deficient pseudomonas aeruginosa isolates from an intensive care unit.acylated homoserine lactones (ahls) are self-generated diffusible signal molecules that mediate population density dependent gene expression (quorum sensing) in a variety of gram-negative bacteria, and several virulence genes of human pathogens are known to be controlled by ahls. in this study, strains of pseudomonas aeruginosa, acinetobacter baumannii, escherichia coli and klebsiella pneumoniae, isolated from intensive care patients, were screened for ahl production by using ahl responsive indi ...200516255145
a case of chromobacterium infection after car accident in korea.chromobacterium violaceum is a gram negative straight rod, 0.8-1.2 by 2.5 to 6.0 m, which is motile by one polar flagella and one to four lateral flagella. the organism inhabits soil and water and is often found in semitropical and tropical climates. infections in humans are rare. we report a case of infection caused by strains of c. violaceum. a 38-year-old male patient was admitted to kyunghee university hospital, seoul, korea on july 28th, 2003, after a car accident. the patient had multiple ...200516259070
l-canavanine made by medicago sativa interferes with quorum sensing in sinorhizobium meliloti.sinorhizobium meliloti is a gram-negative soil bacterium, capable of establishing a nitrogen-fixing symbiosis with its legume host, alfalfa (medicago sativa). quorum sensing plays a crucial role in this symbiosis, where it influences the nodulation process and the synthesis of the symbiotically important exopolysaccharide ii (eps ii). s. meliloti has three quorum-sensing systems (sin, tra, and mel) that use n-acyl homoserine lactones as their quorum-sensing signal molecule. increasing evidence i ...200516321947
n-hexanoyl-l-homoserine lactone, a mediator of bacterial quorum-sensing regulation, exhibits plant-dependent stability and may be inactivated by germinating lotus corniculatus seedlings.the half-life of n-hexanoyl-l-homoserine lactone (c6-hsl) was determined under various ph and temperature conditions, and in several plant environments. c6-hsl was sensitive to alkaline ph, a process that was also temperature-dependent. in addition, c6-hsl disappeared from plant environments, i.e. axenic monocot and dicot plants cultivated under gnotobiotic, hydroponic conditions, albeit with variable kinetics. the disappearance was rapid at the root system of legume plants such as clover or lot ...200416329888
cell-cell influences on bacterial community development in aquatic biofilms.dialysis tubing containing spent culture media, when placed in a lake, was colonized by a low diversity of bacteria, whereas abiotic controls had considerable diversity. changes were seen in the presence and absence of acylated homoserine lactones, suggesting that these molecules and other factors may influence adherent-population composition.200516332906
production of acylated homoserine lactones by aeromonas and pseudomonas strains isolated from municipal activated sludge.up to now, the production and role of n-acyl homoserine lactones (ahls) in activated sludge have been poorly understood. in this study, cross-feeding assays with the reporter strains agrobacterium tumefaciens ntl4 and chromobacterium violaceum cv026 were used to investigate ahl signal production by municipal activated sludge samples. ahl signal production was consistently detected from municipal activated sludge when different samples were incubated on nutrient media. from one municipal activate ...200516333331
geometric constraints at the surfactant headgroup: effect on lipase activity in cationic reverse micelles.the primary objective of the present article is to understand how the geometric constraints at the surfactant head affect the lipase activity in the reverse micellar interface. to resolve this issue, surfactants were designed and synthesized, and activity was measured in /water/isooctane/n-hexanol reverse micellar systems at z ([alcohol]/[surfactant])=5.6, ph 6.0 (20 mm phosphate), 25 degrees c across a varying range of w0 ([water]/[surfactant]) using p-nitrophenylalkanoates as the substrate. it ...200516342982
violacein synergistically increases 5-fluorouracil cytotoxicity, induces apoptosis and inhibits akt-mediated signal transduction in human colorectal cancer cells.despite recent additions to the armory of chemotherapeutic agents for colorectal cancer (crc) treatment, the results of chemotherapy remain unsatisfactory. 5-fluorouracil (5-fu) still represents the cornerstone of treatment and resistance to its actions is a major obstacle to successful chemotherapy. therefore, new active agents in crc and agents that increase the chemosensitivity of cancer cells to 5-fu are still urgently required. violacein, a pigment isolated from chromobacterium violaceum in ...200616344270
diversity dynamics of marine bacteria studied by immunofluorescent staining on membrane filters.of 34 strains of marine bacteria isolated on a general seawater medium, 5 were selected for detailed studies of their population dynamics in the plankton. the isolates were characterized as aeromonas sp., chromobacterium cf. lividum, vibrio sp., and two pseudomonas spp. specific antibodies were produced by immunization of rabbits, and bacterial cells were stained on black uni-pore membrane filters by an indirect immunofluorescent staining procedure. the method proved to be very specific and prac ...198216345920
variability of the influence of physicochemical factors affecting bacterial adhesion to polystyrene substrata.the role of electrostatic and hydrophobic interactions and solid and liquid surface tensions in the adhesion of four bacterial species (pseudomonas fluorescens, enterobacter cloacae, chromobacterium sp., and flexibacter sp.) to hydrophobic polystyrene petri dishes and to more hydrophilic polystyrene tissue culture dishes was investigated. the effect of electrostatic interactions was investigated by determining the effects of different electrolyte solutions on attachment to and of different elect ...198616347145
denitrification by chromobacterium host (rana catesbiana)-associated and two free-living mesophilic strains of bacteria with violet pigmentation and biochemical characteristics of chromobacterium violaceum were isolated from freshwater habitats. cells of each freshly isolated strain and of strain atcc 12472 (the neotype strain) grew anaerobically with glucose as the sole carbon and energy source. the major fermentation products of cells grown in trypticase soy broth (bbl microbiology systems, cockeysville, md.) supplemented w ...198616347164
microbial degradation of asphalt.organisms of the genera pseudomonas, chromobacterium, and bacillus capable of degrading asphalt were isolated by enrichment cultures. the asphalt degradation by these organisms varied from 3 to 25% after incubation for 1 week. the effects of temperature, ph, and atmosphere of incubation on asphalt degradation were investigated and were shown to vary with different organisms on the same substrate.196316349633
in vitro testing for genotoxicity of violacein assessed by comet and micronucleus assays.chromobacterium violaceum is a gram (-) bacteria found in water samples and soils from tropical and subtropical regions of the world. violacein, the major pigment produced by these bacteria, has been shown to have antibiotic, antitumoral and trypanocidal activities. in the present work, the genotoxicity of violacein was investigated in four different cell lines by using the alkaline comet assay and in vero cells using the micronucleus test. in the alkaline comet assay, violacein, when tested at ...200616359912
anaerobic nitrate-dependent iron(ii) bio-oxidation by a novel lithoautotrophic betaproteobacterium, strain 2002.microbial nitrate-dependent fe(ii) oxidation is known to contribute to iron biogeochemical cycling; however, the microorganisms responsible are virtually unknown. in an effort to elucidate this microbial metabolic process in the context of an environmental system, a 14-cm sediment core was collected from a freshwater lake and geochemically characterized concurrently with the enumeration of the nitrate-dependent fe(ii)-oxidizing microbial community and subsequent isolation of a nitrate-dependent ...200616391108
anti-quorum sensing activity of medicinal plants in southern florida.bacterial intercellular communication, or quorum sensing (qs), controls the pathogenesis of many medically important organisms. anti-qs compounds are known to exist in marine algae and have the ability to attenuate bacterial pathogenicity. we hypothesized that terrestrial plants traditionally used as medicines may also produce anti-qs compounds. to test this hypothesis, 50 medicinal plants from southern florida were screened for anti-qs activity using two biomonitor strains, chromobacterium viol ...200616406418
[chromobacteriosis in ilhéus, bahia: epidemiologic, clinical and laboratorial investigation].in april/2004, a group of people traveled to a farm in a town in the south of bahia and afterwards, three teenagers from the same family developed symptoms of severe septicemia and two died. the health department carried out an epidemiologic, clinical, laboratory and environmental investigation that resulted in the identification of chromobacterium violaceum, in biological material from one of them, water and soil. this is the first report of the disease in bahia state.200616410927
detection of chromobacterium violaceum by multiplex pcr targeting the prgi, spao, invg, and sipb genes.based on the recently completed genomic sequence of chromobacterium violaceum american type culture collection (atcc) 12472 a multiplex pcr assay targeting the prgi, spao, invg, and sipb genes of the salmonella spi-1 homologue type-iii secretion system was developed. pcr products of 255bp (prgi), 749bp (spao), 1685bp (invg), and 1752bp (sipb) were successfully amplified simultaneously in a single reaction with all chr. violaceum strains investigated whereas other bacteria tested negative. the de ...200616423655
the use of violacein to study biochemical behaviour of saccharomyces cerevisiae cells.violacein, a biochemical compound produced by chromobacterium violaceum which has antichagasic properties, was used to study biochemical behaviour of saccharomyces cerevisiae cells. at 20 microm and 40 microm, violacein did not alter the membrane potential (deltapsi) of s. cerevisae cells, which means that the integrity of the cell membrane was maintained. on the other hand, at 60 microm and 80 microm, violacein produced significant alterations in the membrane potential. this information will be ...200516435565
production and properties of the native chromobacterium violaceum fucose-binding lectin (cv-iil) compared to homologous lectins of pseudomonas aeruginosa (pa-iil) and ralstonia solanacearum (rs-iil).chromobacterium violaceum is a versatile, violet pigment (violacein)-producing beta-proteobacterium, confined to tropical and subtropical regions, dwelling in soil and water, like pseudomonas aeruginosa and ralstonia solanacearum. these three bacteria are saprophytes that occasionally become aggressive opportunistic pathogens virulently attacking animals (the first two) and plants (the third). the recent availability of their genome sequences enabled identification in the c. violaceum genome of ...200616436433
an investigation of chlorophenol proton affinities and their influence on the biological activity of microorganisms.the proton affinities of 15 chlorophenols are calculated by ab initio methods. straight correlation between proton affinities and changes in the electronic structure is observed. the proton affinities decrease linearly with the electronic density gain on the chlorine atoms, as the liberation of the proton increases. to confirm the importance of the proton affinities on the toxicity of chlorophenols, calorimetric responses of these molecules and related ones where the acid proton is changed to a ...200616451037
chromobacterium violaceum infection in two dogs.chromobacterium violaceum is a saprophyte of soil and water in tropical and subtropical environments that is associated with rare but highly fatal infections in animals and humans. systemic infection was diagnosed in two critically ill dogs from florida. fever was absent in both dogs. both dogs were treated surgically and provided with intensive care, but only one survived. the identification of characteristic, violet-pigmented bacterial colonies on routine microbial cultures should alert microb ...200616527917
chromobacterium violaceum, var. manilae as a pathogenic microörganism. 194216560589
effects of cyanide and dissolved oxygen concentration on biological au recovery.the number of discarded electric devices containing traces of au is currently increasing. it is desirable to recover this au because of its valuable physicochemical properties. au is usually dissolved with relatively high concentrations of cyanide, which is associated with environmental risk. chromobacterium violaceum is able to produce and detoxify small amounts of cyanide, and may thus be able to recover au from discarded electric devices. this study investigated the effects of cyanide and dis ...200616567012
important unusual infections in australia: a critical care review a number of the important unusual infections in australia that can lead to critical illness.200116573516
aquitalea magnusonii gen. nov., sp. nov., a novel gram-negative bacterium isolated from a humic lake.a gram-negative, rod-shaped, non-spore-forming betaproteobacterium (tro-001dr8t) was isolated from humic-lake samples collected from northern wisconsin, usa. on the basis of 16s rrna gene sequence analysis, strain tro-001dr8t belonged to the family neisseriaceae, and the phylogenetic distance from its closest relative, chromobacterium violaceum, was 95 %. strain tro-001dr8t lacked the violet pigmentation of c. violaceum and shared only 26 % dna-dna relatedness with c. violaceum. the dna g+c cont ...200616585708
alginate-chaperoned facile refolding of chromobacterium viscosum lipase.urea denatured lipase from chromobacterium viscosum lipase could be refolded by addition of alginate with high guluronic acid content. the refolded molecule could be recovered by affinity precipitation. this approach resulted in recovery of 80% (of original activity) as compared to classical dilution method which gave only 21% activity recovery. dynamic light scattering showed that binding required about 45 min and activity data obtained from affinity precipitation experiments indicated that ref ...200616624637
ecthyma gangrenosum and septic shock syndrome secondary to chromobacterium violaceum.chromobacterium violaceum is a gram-negative bacterium of soil and water in tropical and subtropical environments. typically, it is considered a bacterium of low virulence although, uncommonly, it causes human infection, particularly in persons with defects in host defenses. infection generally follows exposure of broken skin to contaminated water and soil, and is often characterized by pustules, lymphadenitis, fever, and vomiting, as well as rapid dissemination and a high mortality rate. unfort ...200616631946
epr and uv-vis studies of the nitric oxide adducts of bacterial phenylalanine hydroxylase: effects of cofactor and substrate on the iron environment.phenylalanine hydroxylase from chromobacterium violaceum (cpah), which catalyzes phenylalanine oxidation to tyrosine, is homologous to the catalytic domain of eukaryotic pahs. previous crystallographic and spectroscopic studies on mammalian pah conflict on whether o2 binds to the open-coordination site or displaces the remaining water ligand to yield either a six- or a five-coordinate iron, respectively. the abilities of nitric oxide to behave as an oxygen mimic and a spectroscopic probe of ferr ...200616676991
chromobacterium violaceum infection. 200616681318
inhibition of bacterial quorum sensing by vanilla extract.the purpose of this study was to search for a novel quorum sensing inhibitor and analyse its inhibitory activity.200616706905
on the pigment produced by chromobacterium violaceum. 192716743932
fatal septicaemia from chromobacterium violaceum: case reports and review of the literature.chromobacterium violaceum rarely causes infection in humans and its mechanism of pathogenicity is not well understood. human infection carries a high mortality rate with a fulminating clinical progression. a high index of suspicion is required for diagnosis, and is based on recovering the organisms from blood cultures or other appropriate specimens. we present three cases of human infection managed in a tertiary referral hospital in hong kong with a review of the literature.200616760554
unusual entropy-driven affinity of chromobacterium violaceum lectin cv-iil toward fucose and mannose.the purple pigmented bacterium chromobacterium violaceum is a dominant component of tropical soil microbiota that can cause rare but fatal septicaemia in humans. its sequenced genome provides insight into the abundant potential of this organism for biotechnological and pharmaceutical applications and allowed an orf encoding a protein that is 60% identical to the fucose binding lectin (pa-iil) from pseudomonas aeruginosa and the mannose binding lectin (rs-iil) from ralstonia solanacearum to be id ...200616768446
physicochemical studies on cetylammonium bromide and its modified (mono-, di-, and trihydroxyethylated) head group analogues. their micellization characteristics in water and thermodynamic and structural aspects of water-in-oil microemulsions formed with them along with n-hexanol and isooctane.the micellization behavior of cetylammonium bromide and its mono-, di-, and trihydroxyethylated head group analogues and water/oil (w/o) microemulsion formation with them have been studied with detailed thermodynamic and structural considerations. the critical micellar concentration, micellar aggregation number, and behavior of the surfactants at the air/solution interface have been studied in detail. the results have been analyzed and discussed. the formation of the w/o microemulsion stabilized ...200616771402
[chromobacterium violaceum peritonitis: case report and literature review].we report a case of chromobacterium violaceum infection and we review the literature for all published cases. c. violaceum grew from a peritoneal fluid of a 47-year-old woman operated on for peritonitis following perforative gastroduodenal ulcer. she was just coming back from a 1-month-holyday in french guyana, where she might have been in contact with this micro-organism. the patient fully recovered after surgical management associated with antibiotic therapy consisting of ofloxacin plus pipera ...200616829475
reevaluation of the violacein biosynthetic pathway and its relationship to indolocarbazole biosynthesis.the biosynthetic pathways for violacein and for indolocarbazoles (rebeccamycin, staurosporine) include a decarboxylative fusion of two tryptophan units. however, in the case of violacein, one of the tryptophans experiences an unusual 1-->2 shift of the indole ring. the violacein biosynthetic gene cluster was previously reported to consist of four genes, vioabcd. here we studied the violacein pathway through expression of vio genes in escherichia coli and streptomyces albus. a pair of genes (vioa ...200616874749
cytotoxic activity of violacein in human colon cancer cells.several studies have shown that violacein, a purple pigment extracted from chromobacterium violaceum, is capable to induce apoptosis in a variety of cancer cells, including those leukemia cell lines. herein, we examined the effects of violacein on reactive oxygen species (ros) production during the apoptotic colon cancer cell death. we demonstrate that violacein mediates ros production followed by activation of caspase-3, release of cytochrome c, and calcium release to citosol in caco-2 cells. m ...200616889929
[soft tissue infection in a diabetic patient from a subtropical region]. 200616956538
mouse and human cell activation by n-dodecanoyl-dl-homoserine lactone, a chromobacterium violaceum autoinducer.chromobacterium violaceum produces autoinducers, including homoserine lactones (hsls), for genetic regulation. among the seven hsls derived from c. violaceum we evaluated, only c(12)-hsl stimulated the production of inflammatory cytokines in mammalian monocytic cell lines through the activation of the nf-kappab signaling pathway besides their quorum-sensing role, like 3-oxo-c(12)-hsl from pseudomonas aeruginosa.200616982829
chromobacterium violaceum: a case report of an unusual bacterium causing puerperal sepsis.human infections by chromobacterium violaceum are rare. till date 6 cases have been reported from southern and eastern parts of india. we report here a case of puerperal sepsis by c. violaceum, probably the first case from eastern part of orissa. the patient was successfully treated with amikacin and gatifloxacin.200617001920
structures of human n-acetylglucosamine kinase in two complexes with n-acetylglucosamine and with adp/glucose: insights into substrate specificity and regulation.n-acetylglucosamine (glcnac), a major component of complex carbohydrates, is synthesized de novo or salvaged from lysosomally degraded glycoconjugates and from nutritional sources. the salvage pathway requires that glcnac kinase converts glcnac to glcnac-6-phosphate, a component utilized in udp-glcnac biosynthesis or energy metabolism. glcnac kinase belongs to the sugar kinase/hsp70/actin superfamily that catalyze phosphoryl transfer from atp to their respective substrates, and in most cases cat ...200617010375
antioxidant properties of violacein: possible relation on its biological function.violacein, a violet pigment produced by chromobacterium violaceum, has attracted much attention in recent literature due to its pharmacological properties. in this work, the antioxidant properties of violacein were investigated. the reactivity with oxygen and nitrogen reactive species and 1,1-diphenyl-2-picryl-hydrazyl (dpph), a stable free radical, was evaluated. epr studies were carried out to evaluate the reactivity with the hydroxyl radical. the action of violacein against lipid peroxidation ...200617011197
effect of counterions on the activity of lipase in cationic water-in-oil microemulsions.this paper delineates how the different counterions affect the physicochemical properties of the aqueous aggregates and thereby the lipase activities at the interface of cationic water-in-oil microemulsions. to this end, we have synthesized a series of cetyltrimethylammonium-based surfactants, 1-14, having aliphatic, aliphatic with aromatic substitution at the alpha position, and aromatic carboxylate anion as the counterion. the physicochemical characterizations of these aqueous aggregates were ...200617014111
n-acyl homoserine lactones are degraded via an amidolytic activity in comamonas sp. strain d1.comamonas strain d1 enzymatically inactivates quorum-sensing (qs) signal molecules of the n-acyl homoserine lactone (n-ahsl) family, and exhibits the broadest inactivation range of known bacteria. it degrades n-ahsl with acyl-side chains ranging from 4 to 16 carbons, with or without 3-oxo or 3-hydroxy substitutions. n-ahsl degradation yields hsl but not n-acyl homoserine: strain d1 therefore harbors an amidohydrolase activity. strain d1 is the fifth bacterium species in which an n-ahsl amidohydr ...200717136382
the serratia-type hemolysin of chromobacterium violaceum.chromobacterium violaceum is a gram-negative opportunistic human pathogen and an inhabitant of tropical soils and waterways. although known primarily for the synthesis of the pigment violacein, and more recently as a reporter strain for quorum sensing, clinical reports of chromobacteriosis comprise the largest block of published literature on this organism. genome sequencing has revealed many potential virulence factors in this microorganism, and this paper establishes the presence in c. violace ...200717169000
in vitro biosynthesis of violacein from l-tryptophan by the enzymes vioa-e from chromobacterium violaceum.the purple chromobacterial pigment violacein arises by enzymatic oxidation and coupling of two molecules of l-tryptophan to give a rearranged pyrrolidone-containing scaffold in the final pigment. we have purified five contiguously encoded proteins vioa-e after expression in escherichia coli and demonstrate the full 14-electron oxidation pathway to yield the final chromophore. the flavoenzyme vioa and the heme protein viob work in conjunction to oxidize and dimerize l-tryptophan to a nascent prod ...200617176066
crystallization and preliminary x-ray diffraction analysis of omega-amino acid:pyruvate transaminase from chromobacterium violaceum.the enzyme omega-transaminase catalyses the conversion of chiral omega-amines to ketones. the recombinant enzyme from chromobacterium violaceum has been purified to homogeneity. the enzyme was crystallized from peg 4000 using the microbatch method. data were collected to 1.7 a resolution from a crystal belonging to the triclinic space group p1, with unit-cell parameters a = 58.9, b = 61.9, c = 63.9 a, alpha = 71.9, beta = 87.0, gamma = 74.6 degrees . data were also collected to 1.95 a from a sec ...200717277454
cloning and high-level production of a chitinase from chromobacterium sp. and the role of conserved or nonconserved residues on its catalytic activity.a gene encoding an alkaline (pi of 8.67) chitinase was cloned and sequenced from chromobacterium sp. strain c-61. the gene was composed of 1,611 nucleotides and encoded a signal sequence of 26 n-terminal amino acids and a mature protein of 510 amino acids. two chitinases of 54 and 52 kda from both recombinant escherichia coli and c-61 were detected on sds-page. maximum chitinase activity was obtained in the culture supernatant of recombinant e. coli when cultivated in tb medium for 6 days at 37 ...200717294188
a fatal case of chromobacterium violaceum septicemia in hong kong.chromobacterium violaceum causes a rare infection in human, usually in tropical or subtropical areas. we report a fatal case of c. violaceum infection affecting a 40-year-old previously healthy man in hong kong. he presented with a wound infection and lymphadenitis. despite multiple antibiotic treatment, including ciprofloxacin, he succumbed shortly after admission to the hospital. we report the epidemiological investigation findings and discuss the possible sources of infection. physicians shou ...200617333774
nonionic surfactants: a key to enhance the enzyme activity at cationic reverse micellar interface.the primary objective of the present study is to understand how the different nonionic surfactants modify the anisotropic interface of cationic water-in-oil (w/o) microemulsions and thus influences the catalytic efficiency of surface-active enzymes. activity of chromobacterium viscosum lipase (cv-lipase) was estimated in several mixed reverse micelles prepared from ctab and four different nonionic surfactants, brij-30, brij-92, tween-20, and tween-80/water/isooctane/n-hexanol at different z ([co ...200717348695
stereochemical course of tryptophan dehydrogenation during biosynthesis of the calcium-dependent lipopeptide antibiotics.[reaction: see text] hydrogen atoms are abstracted from the c2' and c3'-pro-s positions of an (s)-tryptophanyl precursor, with overall syn stereochemistry, during the biosynthesis of the c-terminal z-2',3'-dehydrotryptophan residue of the calcium-dependent lipopeptide antibiotics (cdas) in streptomyces coelicolor. the absence of beta-hydroxytryptophanyl, or other possible intermediates, further suggests a direct dehydrogenation mechanism similar to that proposed for the l-tryptophan 2',3'-oxidas ...200717355143
inhibitory effects of histone deacetylase inhibitor depsipeptide on benzo(a)pyrene- and cyclophosphamide-induced genotoxicity in swiss albino mice.depsipeptide (fk228 or fr901228) was evaluated in the mouse bone marrow micronucleus test for its possible protective effect against chromosomal damage induced by benzo(a)pyrene and cyclophosphamide. three doses of depsipeptide (0.5, 1, and 1.5 mg/kg body weight) were given intravenously to mice for 7 consecutive days prior to administration of genotoxins under investigation. all the three doses of depsipeptide were effective in exerting a protective effect against both benzo(a)pyrene and cyclop ...200717365146
the effect of quorum-sensing blockers on the formation of marine microbial communities and larval attachment.we studied the effect of the quorum-sensing (qs) blockers 5-hydroxy-3[(1r)-1-hydroxypropyl]-4-methylfuran-2(5h)-one (fur1), (5r)-3,4-dihydroxy-5-[(1s)-1,2-dihydroxyethyl]furan-2(5h)-one (fur2) and triclosan (tri) on the formation of bacterial biofilms, and the effect of these biofilms on the larval attachment of the polychaete hydroides elegans and the bryozoan bugula neritina. 14-day-old subtidal biofilms were harvested from artificial substrata and were allowed to develop in the laboratory wit ...200717371321
genetic organization of the biosynthetic gene cluster for the indolocarbazole k-252a in nonomuraea longicatena jcm 11136.indolocarbazole metabolite k-252a is a natural product that was previously reported as a potent protein kinase c inhibitor with in vitro and in vivo potency. from a biosynthetic viewpoint, this compound possesses structurally interesting features such as an unusual furanosyl sugar moiety, which are absent in the well-studied staurosporine and rebeccamycin. a cosmid library from genomic dna of nonomuraea longicatena jcm 11136 was constructed and screened for the presence of genes to be involved i ...200717396254
characterization of a gene cluster responsible for the biosynthesis of anticancer agent fk228 in chromobacterium violaceum no. 968.a gene cluster responsible for the biosynthesis of anticancer agent fk228 has been identified, cloned, and partially characterized in chromobacterium violaceum no. 968. first, a genome-scanning approach was applied to identify three distinctive c. violaceum no. 968 genomic dna clones that code for portions of nonribosomal peptide synthetase and polyketide synthase. next, a gene replacement system developed originally for pseudomonas aeruginosa was adapted to inactivate the genomic dna-associated ...200717400765
signal mimics derived from a metagenomic analysis of the gypsy moth gut microbiota.bacterial signaling is an important part of community life, but little is known about the signal transduction pathways of the as-yet-uncultured members of microbial communities. to address this gap, we aimed to identify genes directing the synthesis of signals in uncultured bacteria associated with the midguts of gypsy moth larvae. we constructed a metagenomic library consisting of dna extracted directly from the midgut microbiota and analyzed it using an intracellular screen designated metrex, ...200717435000
chromobacterium subtsugae sp. nov., a betaproteobacterium toxic to colorado potato beetle and other insect pests.strain praa4-1(t), a motile, gram-negative, violet-pigmented bacterium, was isolated from maryland forest soil and found to be orally toxic to colorado potato beetle larvae and other insects. morphological, biological, biochemical and molecular characterization revealed that this strain was most similar to chromobacterium violaceum, the type species and only currently recognized member of the genus chromobacterium. dna-dna hybridization with c. violaceum atcc 12472(t) was 27 %. phylogenetic anal ...200717473247
gulbenkiania mobilis gen. nov., sp. nov., isolated from treated municipal wastewater.a bacterial strain (e4fc31(t)) isolated from treated municipal wastewater was characterized phenotypically and phylogenetically. cells were gram-negative, curved rods with a polar flagellum. the isolate was catalase-, oxidase- and arginine dihydrolase-positive, and able to grow between 15 and 45 degrees c and between ph 5.5 and 9.0. the predominant fatty acids were c(16 : 1)/iso-c(15 : 0) 2-oh and c(16 : 0), the major respiratory quinone was ubiquinone 8 and the g+c content of the genomic dna wa ...200717473267
dietary phytochemicals as quorum sensing inhibitors.quorum sensing (qs) is a cell density dependent expression of species in bacteria mediated by hormone like compounds called autoinducers (ai). several processes responsible for successful establishment of bacterial infection are mediated by qs. inhibition of qs is therefore being considered as a new target for antimicrobial chemotherapy. dietary phytochemicals are secondary metabolites in plants known to have several health benefits including antimicrobial activity. however, their ability to inh ...200717499938
analysis of chromobacterium sp. natural isolates from different brazilian ecosystems.chromobacterium violaceum is a free-living bacterium able to survive under diverse environmental conditions. in this study we evaluate the genetic and physiological diversity of chromobacterium sp. isolates from three brazilian ecosystems: brazilian savannah (cerrado), atlantic rain forest and amazon rain forest. we have analyzed the diversity with molecular approaches (16s rrna gene sequences and amplified ribosomal dna restriction analysis) and phenotypic surveys of antibiotic resistance and b ...200717584942
inhibition of quorum sensing-regulated behaviors by scorzonera sandrasica.many gram-negative bacteria use n-acyl homoserine lactone signal molecules to monitor their own population density and coordinate gene regulation in a process called quorum sensing (qs). increasing evidence implies that certain eukaryotes produce qs-inhibitory compounds. in this work, we tested 46 terrestrial plants materials for their ability to inhibit qs-regulated behaviors in different bacterial species. plant materials were dried and extracted using different solvents. the chloroform-solubl ...200717597339
toxicity of chromobacterium subtsugae to southern green stink bug (heteroptera: pentatomidae) and corn rootworm (coleoptera: chrysomelidae).diabrotica spp. (coleoptera: chrysomelidae) beetles and southern green stink bugs, nezara viridula (l.) (heteroptera: pentatomidae), are pests on corn, zea mays l., and soybean, glycine max (l.) merr., as well as on cucurbits. control of these insects has depended on chemicals. an alternative to chemical control is the use of biologicals. use of bacteria, fungi, viruses, pheromones, and metabolites to control these insects can potentially improve resistance management and reduce pesticide use. o ...200717598525
chromobacterium violaceum infection in taiwan: a case report and literature review.chromobacterium violaceum is a facultative anaerobic, gram-negative bacillus which inhabits stagnant water in tropical and subtropical regions. we describe the case of an 80-year-old female patient with c. violaceum bacteremia due to traumatic wound infected by contaminated water and soil. she had persistent fever, hypotension and neutrophilic leukocytosis on admission. two sets of blood cultures yielded c. violaceum. the patient was successfully treated with levofloxacin. since the first case f ...200717639170
multidrug resistant chromobacterium violaceum: an unusual bacterium causing long standing wound abscess. 200317643028
one step engineering of t7-expression strains for protein production: increasing the host-range of the t7-expression system.the t7-expression system has been very useful for protein expression in escherichia coli. however, it is often desirable to over-express proteins in species other than e. coli. here, we constructed an inducible broad-host-range t7-expression transposon, which allows simple one-step construction of t7-expression strains in various species, providing the option to over-express proteins of interest in a broader host-range. this transposon contains the t7 rna polymerase driven by the lacuv5 promoter ...200717716915
bacterial stimulation of sporangium production in phytophthora cinnamomi.bacteria, notably chromobacterium violaceum, stimulate initiation of production of sporangia by phytophthora cinnamomi, a plant pathogen which does not produce this asexual stage in ordinary agar or liquid culture.196517742598
evaluation of different compounds as quorum sensing inhibitors in pseudomonas aeruginosa.quorum sensing (qs) controls systems affecting the pathogenicity of many microorganisms; its interruption has an anti-pathogenic effect and can be used in the treatment of bacterial infections. in this study we evaluated qs regulation by pseudomonas aeruginosa strains and qs inhibition (qsi) by different compounds. the inhibitory activity of 3 macrolide and 3 lincosamide drugs, resveratrol, garlic extract and n-acetylcysteine was tested on 4 p. aeruginosa strains isolated from cystic fibrosis (c ...200717855182
sepsis by chromobacterium violaceum: first case report from colombia.chromobacterium violaceum is found in tropical and subtropical regions; it is the only chromobacterium species pathogenic for humans. due to its rare presentation, physicians often ignore the importance of this pathogen. we report a fulminant fatal case of bacteremia in a 38-year-old colombian man. the clinical manifestations were fever, thoracic pain, respiratory failure and death. his condition, from the beginning of clinical diagnosis, went into continuous deterioration, till his death, withi ...200717874003
[chromobacterium violaceum septicemia: first case report in the french west indies].we report a fatal case of chromobacterium violaceum septicemia in a 42-year-old farm worker living in the french west indies. the bacteria found in the muddy soil and the stagnant water of tropical and subtropical regions is rarely a source of human infection.200717905550
biosynthesis of violacein: a genuine intermediate, protoviolaceinic acid, produced by vioabde, and insight into vioc function.a biosynthetic intermediate of violacein produced by the mixed enzymes of vioabde was elucidated to be 5-(5-hydroxy-1h-indol-3-yl)-3-(1h-indol-3-yl)-1h-pyrrole-2-carboxylic acid, named protoviolaceinic acid, indicating that vioc, responsible for the final biosynthetic step, works to oxygenate at the 2-position of the right side indole ring, and that the oxygenation reaction to form the central pyrrolidone core proceeds in a non-enzymatic fashion.200717925955
violacein: properties and biological activities.the violet pigment violacein is an indole derivative, isolated mainly from bacteria of the genus chromobacterium, which exhibits important antitumoral, antimicrobial and antiparasitary properties. furthermore, the formulation of violacein in different polymeric carriers developed so far offers alternative approaches to overcoming physiological barriers and undesirable physicochemical properties in vivo, thus improving its efficacy.200717927569
isolation and characterization of two groups of novel marine bacteria producing violacein.thirteen strains of novel marine bacteria producing a purple pigment were isolated from the pacific coast of japan. they were divided into two groups based on their 16s ribosomal rna gene sequences, and both groups of bacteria belonged to the genus pseudoalteromonas. the uv-visible spectrum of the pigment was identical to those of violacein, a pigment produced by several species of bacteria including chromobacterium violaceum, an opportunistic pathogen. further analysis of the chemical structure ...200817968625
a study of natural attenuation processes involved in a microcosm model of a crude oil-impacted wetland sediment in the niger delta.sediment sample from a previously impacted ochani stream was recreated in four glass chambers (a-d) as microcosms. the aim was to model and compare natural attenuation processes to forced aeration for remediation of a crude oil-impacted ecosystem. the initial hydrocarbon concentration was 90,212 mg/kg of sediment. after 60 days, the natural attenuation processes of photooxidation, evaporation, volatilization and biodegradation accounted for 31.9% of the total hydrocarbon removed while 13% was at ...200817988860
[sepsis caused by pigmented and no pigmented chromobacterium violaceum].chromobacterium violaceum sepsis is rare but associated with a high mortality rate. we report a fatal case of c. violaceum sepsis in a 6 years old venezuelan indian boy. clinical manifestations were fever and swelling in the right inguinal region. the initial diagnosis was an appendicular plastron. appendicectomy was performed and during surgery a right psoas abscess was identified that resulted culture positive for pigmented c. violaceum. blood cultures were positive for a pigmented and non pig ...200717989847
effect of the pretreatment of lipase with organic solvents on its conformation and activity in reverse micelles.the activity and conformation of chromobacterium viscosum lipase-pretreated with various organic solvents were investigated. the pretreatment of lipase led to a substantial increase of enzyme activity in aot (sodium bis [2-ethyl -1-hexyl] sulfosuccinate)/isooctane/water reverse micelles. among the organic solvents used, n-hexane was found to be most effective. it was observed that higher hexane content with shorter agitation time and vice versa had almost the same effect on the initial activity ...200718025586
improved activity of enzymes in mixed cationic reverse micelles with imidazolium-based surfactants.this work reports the significant enhancement in performance of interfacially active enzymes, chromobacterium viscosum (cv) lipase and horseradish peroxidase (hrp) in mixed reverse micelles of cetyltrimethylammonium bromide (ctab) and imidazolium-based amphiphiles having varying tail lengths. lipase activity in these mixed systems was always higher than that in the individual cationic reverse micelles of ctab or any imidazolium surfactant, highest being observed in the mixed system of ctab (50 m ...200818067868
chemical durability, specular gloss, and transmittance of optical glasses. 194818101639
fatal septicemia caused by chromobacterium violaceum in a child from colombia.a 4-year old child living in colombia presented with a history of fever and severe abdominal pain for four days. the patient developed pneumonia, septic shock, multiple organ failure and died on the fifth day of hospitalization. chromobacterium violaceum was isolated from admission blood cultures and was resistant to ampicillin, cephalosporins, carbapenems and aminoglycosides.200718157408
the violacein biosynthetic enzyme vioe shares a fold with lipoprotein transporter proteins.vioe, an unusual enzyme with no characterized homologues, plays a key role in the biosynthesis of violacein, a purple pigment with antibacterial and cytotoxic properties. without bound cofactors or metals, vioe, from the bacterium chromobacterium violaceum, mediates a 1,2 shift of an indole ring and oxidative chemistry to generate prodeoxyviolacein, a precursor to violacein. our 1.21 a resolution structure of vioe shows that the enzyme shares a core fold previously described for lipoprotein tran ...200818171675
crystal structure of vioe, a key player in the construction of the molecular skeleton of violacein.violacein and the indolocarbazoles are naturally occurring bisindole products with various biological activities, including antitumor activity. although these compounds have markedly different molecular skeletons, their biosynthetic pathways share the same intermediate "compound x," which is produced from l-tryptophan via indole-3-pyruvic acid imine. compound x is a short-lived intermediate that is spontaneously converted to chromopyrrolic acid for indolocarbazole biosynthesis, whereas vioe tran ...200818171677
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