TitleAbstractYear(sorted ascending)
genetic analysis of violacein biosynthesis by chromobacterium violaceum.chromobacterium violaceum presents a distinctive phenotypic characteristic, the production of a deep violet pigment named violacein. although the physiological function of this pigment is not well understood, the sequencing of the genome of this bacterium has given some insight into the mechanisms and control of violacein production. it was found that erythrose-4-phosphate (e4p), a precursor to aromatic amino acid biosynthesis, is produced by the non-oxidative portion of the hexose monophosphate ...200415100990
chemotaxis and flagellar genes of chromobacterium violaceum.the availability of the complete genome of the gram-negative beta-proteobacterium chromobacterium violaceum has increasingly impacted our understanding of this microorganism. this review focuses on the genomic organization and structural analysis of the deduced proteins of the chemosensory adaptation system of c. violaceum. c. violaceum has multiple homologues of most chemotaxis genes, organized mostly in clusters in the bacterial genome. we found at least 67 genes, distributed in 10 gene cluste ...200415100991
tolerance to stress and environmental adaptability of chromobacterium violaceum.chromobacterium violaceum is a gram-negative bacterium, abundant in a variety of ecosystems in tropical and subtropical regions, including the water and borders of the negro river, a major component of the amazon basin. as a free-living microorganism, c. violaceum is exposed to a series of variable conditions, such as different sources and abundance of nutrients, changes in temperature and ph, toxic compounds and uv rays. these variations, and the wide range of environments, require great adapta ...200415100992
transport genes of chromobacterium violaceum: an overview.the complete genome sequence of the free-living bacterium chromobacterium violaceum has been determined by a consortium of laboratories in brazil. almost 500 open reading frames (orfs) coding for transport-related membrane proteins were identified in c. violaceum, which represents 11% of all genes found. the main class of transporter proteins is the primary active transporters (212 orfs), followed by electrochemical potential-driven transporters (154 orfs) and channels/pores (62 orfs). other cla ...200415100993
drug resistance in chromobacterium violaceum.chromobacterium violaceum is a free-living bacterium commonly found in aquatic habitats of tropical and subtropical regions of the world. this bacterium is able to produce a large variety of products of biotechnological and pharmacological use. although c. violaceum is considered to be non-pathogenic, some cases of severe infections in humans and other animals have been reported. genomic data on the type strain atcc 12472(t) has provided a comprehensive basis for detailed studies of pathogenicit ...200415100994
chromobacterium violaceum genome: molecular mechanisms associated with pathogenicity.chromobacterium violaceum is a versatile, gram-negative beta-protebacterium that grows in a variety of ecosystems in tropical and subtropical areas, such as the water and borders of the negro river, in the amazon region of brazil. although it is a saprophyte and is generally considered non-pathogenic, sporadic cases of human infection have been described, mainly in young children and in immunodeficient individuals. although rare, infections with c. violaceum are characterized by rapid disseminat ...200415100995
energetic metabolism of chromobacterium violaceum.chromobacterium violaceum is a free-living microorganism, normally exposed to diverse environmental conditions; it has a versatile energy-generating metabolism. this bacterium is capable of exploiting a wide range of energy resources by using appropriate oxidases and reductases. this allows c. violaceum to live in both aerobic and anaerobic conditions. in aerobic conditions, c. violaceum is able to grow in a minimal medium with simple sugars, such as glucose, fructose, galactose, and ribose; bot ...200415100996
dna repair in chromobacterium violaceum.chromobacterium violaceum is a gram-negative beta-proteobacterium that inhabits a variety of ecosystems in tropical and subtropical regions, including the water and banks of the negro river in the brazilian amazon. this bacterium has been the subject of extensive study over the last three decades, due to its biotechnological properties, including the characteristic violacein pigment, which has antimicrobial and anti-tumoral activities. c. violaceum promotes the solubilization of gold in a mercur ...200415100997
identification of chromobacterium violaceum genes with potential biotechnological application in environmental detoxification.chromobacterium violaceum is a gram-negative bacterium found in a wide variety of tropical and subtropical ecosystems. the complete genome sequence of c. violaceum atcc 12472 is now available, and it has considerable biotechnological potential for various applications, such as environmental detoxification, as well as medical and agricultural use. we examined the biotechnological potential of c. violaceum for environmental detoxification. three operons, comprising the ars operon, involved in arse ...200415100998
molecular mechanism of violacein-mediated human leukemia cell death.violacein, a pigment isolated from chromobacterium violaceum in the amazon river, presents diverse biologic properties and attracts interest as a consequence of its antileukemic activity. elucidation of the molecular mechanism mediating this activity will provide further relevant information for understanding its effects on the cellular physiology of untransformed cells and for considering its possible clinical application. here, we show that violacein causes apoptosis in hl60 leukemic cells but ...200415130948
ym-254890 analogues, novel cyclic depsipeptides with galpha(q/11) inhibitory activity from chromobacterium sp. qs3666.the structure elucidation and biological activity of novel ym-254890 (1) analogues and semi-synthetic derivatives are described. three natural analogues, ym-254891 (2), ym-254892 (3), and ym-280193 (4), were isolated from the fermentation broth of chromobacterium sp. qs3666, and two hydrogenated derivatives, ym-385780 (5) and ym-385781 (6), were synthesized from ym-254890. their structures were determined by one- and two-dimensional nmr studies and mass spectrometry. among these compounds, two n ...200415158780
burkholderia cenocepacia phage bcepmu and a family of mu-like phages encoding potential pathogenesis factors.we have isolated bcepmu, a mu-like bacteriophage whose host range includes human pathogenic burkholderia cenocepacia (formally b. cepacia genomovar iii) isolates, and determined its complete 36748 bp genomic sequence. like enteric bacteriophage mu, the bcepmu genomic dna is flanked by variable host sequences, a result of transposon-mediated replication. the bcepmu genome encodes 53 proteins, including capsid assembly components related to those of mu, and tail sheath and tube proteins related to ...200415184022
use of sinorhizobium meliloti as an indicator for specific detection of long-chain n-acyl homoserine lactones.population-density-dependent gene expression in gram-negative bacteria involves the production of signal molecules characterized as n-acyl homoserine lactones (ahls). the synthesis of ahls by numerous microorganisms has been identified by using biosensor strains based on the agrobacterium tumefaciens and chromobacterium violaceum quorum-sensing systems. the symbiotic nitrogen-fixing bacterium sinorhizobium meliloti is rapidly becoming a model organism for the study of quorum sensing. this organi ...200415184178
effects of natural and chemically synthesized furanones on quorum sensing in chromobacterium violaceum.cell to cell signaling systems in gram-negative bacteria rely on small diffusible molecules such as the n-acylhomoserine lactones (ahl). these compounds are involved in the production of antibiotics, exoenzymes, virulence factors and biofilm formation. they belong to the class of furanone derivatives which are frequently found in nature as pheromones, flavor compounds or secondary metabolites. to obtain more information on the relation between molecular structure and quorum sensing, we tested a ...200415233843
two new bacterial pathogens of colorado potato beetle coleoptera: chrysomelidae).other than bacillus thuringiensis berliner, few bacteria are lethal to the colorado potato beetle (leptinotarsa decemlineata [say]), a major pest of potatoes and eggplant. expanded use of biologicals for the control of colorado potato beetle will improve resistance management, reduce pesticide use, and produce novel compounds for potential use in transgenic plants. using freeze-dried, rehydrated artificial diet in pellet form to screen bacteria lethal to other insects, we determined that strains ...200415279252
a simple screening protocol for the identification of quorum signal antagonists.quorum sensing (qs) is a mechanism by which diverse microorganisms can control specific processes in response to population density. a relatively well-known form of qs among proteobacteria involves production and subsequent response to acylated homoserine lactones (ahls). quorum sensing inhibition (qsi), targeting ahl-dependent signaling, has been reported as a strategy for the control of biofilm formation used by several marine organisms. we developed a simple soft agar overlay protocol, based ...200415279939
flow microcalorimetric studies of phenol and its chlorinated derivatives and a theoretical evaluation of their possible inhibition mode on chromobacterium violaceum respiration.the general belief that chemical structure determines the biological effect of drugs has led to several techniques to establish structure-activity relationships (sar) that is useful in the development of more active compounds. predicting toxic effects based on sar, one can obtain toxicological data with a low cost-benefit ratio. chlorophenols that represent a class of toxic agents frequently used in industrial processes are not satisfactorily described in the literature in relation to their toxi ...200415336391
a novel galphaq/11-selective inhibitor.ym-254890, which was isolated from the culture broth of chromobacterium sp., inhibits adp-induced platelet aggregation and has antithrombotic and thrombolytic effects. ym-254890 blocks galpha(q/11)-coupled adp receptor p2y1-mediated ca(2+) mobilization. here we report that ym-254890 is a selective galpha(q/11) inhibitor. ym-254890 blocked ca(2+) mobilization mediated by several galpha(q/11)-coupled receptors but not by galpha(i)- or galpha(15)-coupled receptor, indicating that phospholipase cbet ...200415339913
[violacein: a molecule of biological interest originating from the soil-borne bacterium chromobacterium violaceum].soil micro-organisms have evolved functions that allow them to withstand the strong competition for survival that characterizes most of their habitats. the production of antibiotic or antifungal compounds is one of these mechanisms. the relevant molecules often exhibit valuable therapeutic properties.200415363621
vioc is a non-heme iron, alpha-ketoglutarate-dependent oxygenase that catalyzes the formation of 3s-hydroxy-l-arginine during viomycin biosynthesis. 200415368580
conversion of (2s)-arginine to (2s,3r)-capreomycidine by vioc and viod from the viomycin biosynthetic pathway of streptomyces sp. strain atcc11861. 200415368582
metal solubilization from metal-containing solid materials by cyanogenic chromobacterium violaceum.different cyanogenic bacterial strains (chromobacterium violaceum, pseudomonas fluorescens, bacillus megaterium) were cultivated under cyanide-forming conditions in the presence of metal-containing solids such as nickel powder or electronic scrap. all microorganisms were able to form water-soluble metal cyanides, however, with different efficiencies. c. violaceum was able to mobilize nickel as tetracyanonickelate [ni(cn)4(2-)] from fine-grained nickel powder. gold was microbially solubilized as ...200415380664
pathologic quiz case: a 13-year-old boy with a 2-day history of fever, vomiting, and mental status changes. chromobacterium violaceum bacteremia. 200415387687
cytotoxic effects of violacein in human uveal melanoma cell lines.violacein is the main pigment produced by chromobacterium violaceum, a saprophytic gram-negative bacillus. violacein is formed by the condensation of two modified tryptophan molecules and has potential anti-neoplastic effects. the purpose of this pilot study was to investigate the in vitro activity of violacein in human uveal melanoma cell lines. human uveal melanoma cell lines 92.1 and ocm-1 were incubated with five different concentrations of violacein (10(-5)-10(-9) m), and the total cellular ...200415457100
an analysis of type-iii secretion gene clusters in chromobacterium violaceum.chromobacterium violaceum is an environmental gram-negative bacterium that is common in soil and water in tropical and sub-tropical regions. it is also a model organism for studying quorum-sensing and is a rare but deadly human pathogen. recent completion of the genome sequence of c. violaceum strain atcc 12472 revealed the presence of genes associated with type-iii secretion systems (ttsss). one of these systems resembles the spi-1 system found in salmonella enterica, whereas another is similar ...200415488386
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
[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
[successful treatment of a case with fatal sepsis caused by chromobacterium violaceum]. 200718282432
fatal septicaemia due to chromobacterium violaceum.human infection caused by chromobacterium violaceum is rare but when it occurs, it is associated with a high mortality rate. this is a report of a young adult male who presented as a surgical emergency and succumbed soon after. the most common feature of this infection is sepsis, followed by cutaneous involvement and liver abscesses. chromobacterium infection as a differential in a case of sepsis is important for clinicians to suspect, especially in tropical countries.200718198747
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
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
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