TitleAbstractYear(sorted descending)
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
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
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
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
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
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 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
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
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
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
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
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
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
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
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
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
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
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
a new method of synthesis and antibacterial activity evaluation of piper amides.several natural piper amides and their mimics were synthesized by developing a new strategy of amide formation. the piper amides were tested against both gram +ve and gram -ve bacterial strains and found that they are particularly more active against staphylococcus aureus and chromobacterium violaceum strains.200414974622
role of the second coordination sphere residue tyrosine 179 in substrate affinity and catalytic activity of phenylalanine hydroxylase.phenylalanine hydroxylase converts phenylalanine to tyrosine utilizing molecular oxygen and tetrahydropterin as a cofactor, and belongs to the aromatic amino acid hydroxylases family. the catalytic domains of these enzymes are structurally similar. according to recent crystallographic studies, residue tyr179 in chromobacterium violaceum phenylalanine hydroxylase is located in the active site and its hydroxyl oxygen is 5.1 a from the iron, where it has been suggested to play a role in positioning ...200414999516
impact of violacein-producing bacteria on survival and feeding of bacterivorous nanoflagellates.we studied the role of bacterial secondary metabolites in the context of grazing protection against protozoans. a model system was used to examine the impact of violacein-producing bacteria on feeding rates, growth, and survival of three common bacterivorous nanoflagellates. freshwater isolates of janthinobacterium lividum and chromobacterium violaceum produced the purple pigment violacein and exhibited acute toxicity to the nanoflagellates tested. high-resolution video microscopy revealed that ...200415006783
pathogenomics of non-pathogens.analysing the genomes of non-pathogenic microorganisms, in addition to its basic and applied scientific interest, can also shed considerable light on the study of pathogenic microorganisms. two of the three microorganisms described here are rarely pathogenic, but carry genetic determinants that have previously been identified as being important for the pathogenicity of other microorganisms. this underlines the growing understanding that many so-called 'virulence genes' are probably involved in m ...200415040257
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
[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
microbial genomics: tropical treasure?a brazilian consortium has unveiled the genomic dna sequence of the purple-pigmented bacterium chromobacterium violaceum, a dominant component of the tropical soil microbiota. the sequence provides insight into the abundant potential of this organism for biotechnological and pharmaceutical applications.200414738751
characterisation of steryl esterase activities in commercial lipase preparations.triglycerides, steryl esters, resin acids, free fatty acids and sterols are lipophilic extractives of wood (commonly referred to as pitch or wood resin) and have a negative impact on paper machine runnability and quality of paper. thus, enzymes capable of modifying these compounds would be potential tools for reducing pitch problems during paper manufacture. in this work, 19 commercial lipase preparations were tested for their ability to degrade steryl esters, which may play a significant role i ...200414741769
toward pku enzyme replacement therapy: pegylation with activity retention for three forms of recombinant phenylalanine hydroxylase.phenylketonuria (pku) is a disease in which phenylalanine and phenylalanine-derived metabolites build up to neurotoxic levels due to mutations in the phenylalanine hydroxylase gene (pah). enzyme replacement therapy is a viable option to supply active pah. however, the inherent protease sensitivity and potential immunogenicity of pah have precluded adoption of this approach. in this report, we have used polyethylene glycol derivatization (pegylation) to produce protected forms of pah for potentia ...200414741785
a new set of bioinformatics tools for genome projects.a new tool called system for automated bacterial integrated annotation--sabia (sabia being a very well-known bird in brazil) was developed for the assembly and annotation of bacterial genomes. this system performs automatic tasks of assembly analysis, orfs identification/analysis, and extragenic region analyses. genome assembly and contig automatic annotation data are also available in the same working environment. the system integrates several public domains and newly developed software program ...200415100986
closure of rrna related gaps in the chromobacterium violaceum genome with the pcr-assisted contig extension (pace) the finishing phase of the chromobacterium violaceum genome project, the shotgun sequences were assembled into 57 contigs that were then organized into 19 scaffolds, using the information from shotgun and cosmid clones. among the 38 ends resulting from the 19 scaffolds, 10 ended with sequences corresponding to rrna genes (seven ended with the 5s rrna gene and three ended with the 16s rrna gene). the 28 non-ribosomal ends were extended using the pcr-assisted contig extension (pace) methodology ...200415100987
gene expression in chromobacterium violaceum.the repertoire of 4,431 open reading frames (orfs), eight rrna operons and 98 trna genes of chromobacterium violaceum must be expressed in a regulated manner for successful adaptation to a wide variety of environmental conditions. to accomplish this feat, the organism relies on protein machineries involved in transcription, rna processing and translation. analysis of the c. violaceum genome showed that transcription initiation, elongation and termination are performed by the five well-known rna ...200415100988
bacteriophages and insertion sequences of chromobacterium violaceum atcc 12472.a fluid genome is a great advantage to prokaryotes, enabling quick adaptation to various types of ecological niches and to diverse environmental selective pressures. a substantial portion of these sudden changes is mediated by lateral gene transfer (lgt), through genetic recombination mechanisms, such as transformation, conjugation and transduction. the recent sequencing of several organisms has offered a new approach to the study of lgt, using comparison and analysis of nucleotide sequences dis ...200415100989
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
the complete genome sequence of chromobacterium violaceum reveals remarkable and exploitable bacterial adaptability.chromobacterium violaceum is one of millions of species of free-living microorganisms that populate the soil and water in the extant areas of tropical biodiversity around the world. its complete genome sequence reveals (i) extensive alternative pathways for energy generation, (ii) approximately 500 orfs for transport-related proteins, (iii) complex and extensive systems for stress adaptation and motility, and (iv) widespread utilization of quorum sensing for control of inducible systems, all of ...200314500782
improvement in enzyme activity and stability by addition of low molecular weight polyethylene glycol to sodium bis(2-ethyl-l-hexyl)sulfosuccinate/isooctane reverse micellar system.the activity and stability of chromobacterium viscosum lipase (glycerolester hydrolase, ec olive oil hydrolysis in sodium bis (2-ethyl-l-hexyl)sulfosuccinate (aot)/isooctane reverse micelles is increased appreciably when low molecular weight polyethylene glycol (peg 400) is added to the reverse micelles. to understand the effect of peg 400 on the phase behavior of the reverse micellar system, the phase diagram of aot/ peg 400/water/isooctane system was studied. the influences ...200314515025
production of acylated homoserine lactones by different serotypes of vibrio anguillarum both in culture and during infection of rainbow trout.onehundred and forty-eight out of onehundred and fifty strains of vibrio anguillarum isolated from vibriosis in danish marine aquaculture produced bacterial communication signals, acylated homoserine lactones, eliciting a response in the agrobacterium tumefaciens (pzlr4) monitoring system. one strain, a serotype o4, induced a strong response in the chromobacterium violaceum (cv026) monitoring system. profiles of ahls determined by tlc separation revealed the presence of at least four ahls and a ...200314529176
cytotoxicity and potential antiviral evaluation of violacein produced by chromobacterium violaceum.natural products are an inexhaustible source of compounds with promising pharmacological activities including antiviral action. violacein, the major pigment produced by chromobacterium violaceum, has been shown to have antibiotic, antitumoral and anti-trypanosoma cruzi activities. the goal of the present work was to evaluate the cytotoxicity of violacein and also its potential antiviral properties. the cytotoxicity of violacein was investigated by three methods: cell morphology evaluation by inv ...200314595466
lipase-catalyzed kinetic resolution on solid-phase via a "capture and release" strategy.the lipase-catalyzed kinetic resolution of (r/s)-3-phenylbutyric acid 2 using solid-supported cyclohexane-1,3-dione (chd) 6 is described. in each case the predominant enantiomer observed, after cleavage from the resin, was (r)-(-)-3-phenylbutyric acid (r)-2 (ee > 99%) rather than the expected (s)-enantiomer of 2. this observation is in contrast to the fact that chromobacterium viscosum lipase shows high enantiospecificity for the (s)-enantiomer in the corresponding solution-phase hydrolysis reac ...200314611219
pcr-assisted contig extension: stepwise strategy for bacterial genome closure.finishing is rate limiting for genome projects, and improvements in the efficiency of complete genome-sequence compilation will require improved protocols for gap closure. here we report a novel approach for extending shotgun contigs and closing gaps that we termed pcr-assisted contig extension (pace). pace depends on the capture of rare mismatched interactions that occur between arbitrary primers and template dna of unknown sequence, even under highly stringent conditions, by means of elevated ...200312661167
order of substrate binding in bacterial phenylalanine hydroxylase and its mechanistic implication for pterin-dependent oxygenases.phenylalanine hydroxylase (pah) is a pterin-dependent non-heme metalloenzyme that catalyzes the oxidation of phenylalanine to tyrosine, which is the rate-limiting step in the catabolism of phe. chromobacterium violaceum phenylalanine hydroxylase (cpah) has been prepared and its steady-state mechanism has been investigated. the enzyme requires iron for maximal activity. initial rate measurements, done in the presence of the 6,7-dimethyl-5,6,7,8-tetrahydropterin (dmph(4)) cofactor, yielded an aver ...200312459906
phagocyte nadph oxidase, but not inducible nitric oxide synthase, is essential for early control of burkholderia cepacia and chromobacterium violaceum infection in mice.reactive oxygen and nitrogen intermediates have critical, partially overlapping roles in host defense against a variety of pathogens. using mice deficient in generating phagocyte superoxide (p47(phox)(-/-)) and mice deficient in generating inducible nitric oxide synthase (inos(-/-)), we examined the roles of these reactive species in host defense against burkholderia cepacia and chromobacterium violaceum, organisms known to have unusual virulence in chronic granulomatous disease. intraperitoneal ...200312496167
violacein and its beta-cyclodextrin complexes induce apoptosis and differentiation in hl60 cells.violacein, a pigment isolated from chromobacterium violaceum, has been reported to have multiple biological activities including in vitro antitumor effects. certain anticancer agents are known to induce apoptosis in human tumor cell lines. in this work, our aim was to investigate the effectiveness of violacein/beta-cyclodextrin (beta-cd)-containing systems to produce lethal effects in the human promyelocytic leukemia cell line hl60. using the mtt tetrazolium reduction test, ic(50) for the inclus ...200312628314
picosecond dynamics of a peptide from the acetylcholine receptor interacting with a neurotoxin probed by tailored tryptophan fluorescence.a tryptophan analog, dehydro-n-acetyl-l-tryptophanamide (delta-nata), which is produced enzymatically via l-tryptophan 2',3'-oxidase from chromobacterium violaceum, is newly used for time-resolved fluorescence. the absorption and emission maxima of delta-nata at 332 and 417 nm, respectively, in 20% dimethylformamide-water are significantly shifted to the red with respect to those of tryptophan in water, permitting us to measure its fluorescence in the presence of tryptophan residues. we demonstr ...200312785053
fatal septicaemia caused by chromobacterium violaceum.we report a case of chromobacterium violaceum septicaemia in a 10-year old boy admitted to hospital in september 2001, two weeks after he suffered a crush injury of the left foot. in spite of surgical debridement and antibiotics his condition worsened and he developed multiple liver and lung abscesses. he died one week after admission and a blood culture grew chromobacterium violaceum.200312795018
[the inhibitory effect of extracts from galla chinensis on marine fouling bacteria].to observe the activity of extracts from galla chinensis with different solvents against marine fouling bacteria in vitro.200312795221
ym-254890, a novel platelet aggregation inhibitor produced by chromobacterium sp. qs3666.a novel platelet aggregation inhibitor, ym-254890, was isolated from the culture broth of strain qs3666. this strain was isolated from a soil sample collected at okutama, tokyo, japan, and was identified as chromobacterium sp. by morphological and physiological criteria. ym-254890 was purified from the culture supernatant by solvent extraction, ods and silica gel flash chromatography, followed by preparative hplc. ym-254890 inhibited adp-induced platelet aggregation in human platelet-rich plasma ...200312817809
chromobacterium violaceum bacteremia: a case report.chromobacterium violaceum is confined in tropical and subtropical regions, which can cause life-threatening disease. it is the only chromobacterium species that is pathogenic to humans. because of its rarity, clinicians often do not appreciate its importance when it is isolated. we report a fulminate fatal case of c. violaceum bacteremia in a 20-year-old male taiwanese. the clinical manifestations were fever and abdominal pain, followed by shock and pulmonary septic embolism. emergent laparotomy ...200312886967
novel bacteria degrading n-acylhomoserine lactones and their use as quenchers of quorum-sensing-regulated functions of plant-pathogenic bacteria.bacteria degrading the quorum-sensing (qs) signal molecule n-hexanoylhomoserine lactone were isolated from a tobacco rhizosphere. twenty-five isolates degrading this homoserine lactone fell into six groups according to their genomic rep-pcr and rrs pcr-rflp profiles. representative strains from each group were identified as members of the genera pseudomonas, comamonas, variovorax and rhodococcus: all these isolates degraded n-acylhomoserine lactones other than the hexanoic acid derivative, albei ...200312904538
production of n-acylhomoserine lactone signal molecules by gram-negative soil-borne and plant-associated bacteria.quorum-sensing control mediated by n-acylhomoserine lactone (ahl) signal molecules has been established as a key feature in the regulation of various metabolic traits in many bacteria. approximately 300 strains representing 6 genera and 18 species of soil-borne and plant-associated gram-negative bacteria isolated in various regions of the former ussr using two reporter systems were screened for ahl production. the production was observed in 17.5% of the screened bacterial strains. positive respo ...200315058194
multidrug resistant chromobacterium violaceum: an unusual bacterium causing long standing wound abscess. 200317643028
molecular cloning and expression of mn(2+)-dependent sphingomyelinase/hemolysin of an aquatic bacterium, pseudomonas sp. strain tk4.we report here the molecular cloning and expression of a hemolytic sphingomyelinase from an aquatic bacterium, pseudomonas sp. strain tk4. the sphingomyelinase gene was found to consist of 1,548 nucleotides encoding 516 amino acid residues. the recombinant 57.7-kda enzyme hydrolyzed sphingomyelin but not phosphatidylcholine, phosphatidylserine, phosphatidylglycerol, phosphatidic acid, or phosphatidylethanolamine, indicating that the enzyme is a sphingomyelin-specific sphingomyelinase c. the hydr ...200211751833
histone deacetylase inhibitor fk228 inhibits tumor angiogenesis.fk228 (formerly fr901228) was recently isolated from chromobacterium violaceum as a potent antitumor agent and its biologic target protein was identified as histone deacetylase (hdac). because of its unique chemical structure (i.e., bicyclic depsipeptide) and activity profile in the national cancer institute's developmental therapeutics program, fk228 is currently in a phase i clinical trial for cancer therapy. in the present study, we investigated the antiangiogenic activity of fk228 in vivo an ...200211774279
chromobacterium violaceum infection: a rare but frequently fatal disease.the authors report a rare case of chromobacterium violaceum infection in a 2-month-old child. she presented with an apparently localized abscess, which appeared to respond well to therapy. however, the infection recurred later with a fulminant course. the organism frequently is dismissed as a contaminant or not identified properly, and the fatality rates are high. a high degree of awareness about this infection needs to be created, especially among pediatricians and pediatric surgeons, because c ...200211781998
a comparison of lipase-catalysed ester and lactone synthesis in low-water systems: analysis of optimum water activity.we investigated the effects of the lyophilisation medium (enzyme plus buffer salt and additives) and of water activity (a(w)) on the catalytic properties of lipase from chromobacterium viscosum (lipase cv) in organic solvents; catalysis of ester and lactone synthesis were compared and, despite the similarities of the reactive groups involved in these reactions, some interesting differences were observed. including 2-[n-morpholino]ethanesulfonic acid (mes) buffer in the lyophilisation medium of l ...200211807759
characterization of n-acyl homoserine lactone overproducing mutants of burkholderia multivorans atcc 17616.burkholderia multivorans atcc 17616 ordinarily produces insufficient amounts of n-acyl homoserine lactones (ahls) to promote ahl-dependent formation of the pigment violacein by the reporter strain chromobacterium violaceum cv026. we have isolated ahl-overproducing mutants of strain 17616 by screening for variants which do cross-feed ahls to strain cv026. nucleotide-sequence analysis of the bmuir locus which specifies ahl synthase (bmui) and ahl-binding transcriptional activator protein (bmur) in ...200211814664
synthesis of monoacyl a-ring precursors of 1alpha,25-dihydroxyvitamin d3 through selective enzymatic efficient synthesis of monoacylated 1alpha,25-dihydroxyvitamin d3 a-ring precursors 15, 16, 18, and 19 has been described through an enzymatic hydrolysis process. candida antarctica a lipase (cal-a) hydrolyzes the c-5 acetate ester in trans stereoisomers 9 and 13, with complete and high selectivity, respectively. in the case of cis isomers 11 and 14, chromobacterium viscosum lipase (cvl) is the enzyme of choice, exhibiting opposite selectivity for these two enantiomers. this lipase selectivel ...200211846672
fluorescent inhibitors reveal solvent-dependent micropolarity in the lipid binding sites of lipases.triacylglycerol analogue p-nitrophenyl phosphonates specifically react with the active-site serine of lipolytic enzymes to give covalent lipase-inhibitor complexes, mimicking the first transition state which is involved in lipase-mediated ester hydrolysis. here we report on a new type of phosphonate inhibitors containing a polarity-sensitive fluorophore to monitor micropolarity around the active site of the enzyme in different solvents. the respective compounds are hexyl and methyl dimethylamino ...200212009403
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