TitleAbstractYear(sorted ascending)
toxicity of chromobacterium subtsugae to southern green stink bug (heteroptera: pentatomidae) and corn rootworm (coleoptera: chrysomelidae).diabrotica spp. (coleoptera: chrysomelidae) beetles and southern green stink bugs, nezara viridula (l.) (heteroptera: pentatomidae), are pests on corn, zea mays l., and soybean, glycine max (l.) merr., as well as on cucurbits. control of these insects has depended on chemicals. an alternative to chemical control is the use of biologicals. use of bacteria, fungi, viruses, pheromones, and metabolites to control these insects can potentially improve resistance management and reduce pesticide use. o ...200717598525
chromobacterium violaceum infection in taiwan: a case report and literature review.chromobacterium violaceum is a facultative anaerobic, gram-negative bacillus which inhabits stagnant water in tropical and subtropical regions. we describe the case of an 80-year-old female patient with c. violaceum bacteremia due to traumatic wound infected by contaminated water and soil. she had persistent fever, hypotension and neutrophilic leukocytosis on admission. two sets of blood cultures yielded c. violaceum. the patient was successfully treated with levofloxacin. since the first case f ...200717639170
evaluation of different compounds as quorum sensing inhibitors in pseudomonas aeruginosa.quorum sensing (qs) controls systems affecting the pathogenicity of many microorganisms; its interruption has an anti-pathogenic effect and can be used in the treatment of bacterial infections. in this study we evaluated qs regulation by pseudomonas aeruginosa strains and qs inhibition (qsi) by different compounds. the inhibitory activity of 3 macrolide and 3 lincosamide drugs, resveratrol, garlic extract and n-acetylcysteine was tested on 4 p. aeruginosa strains isolated from cystic fibrosis (c ...200717855182
sepsis by chromobacterium violaceum: first case report from colombia.chromobacterium violaceum is found in tropical and subtropical regions; it is the only chromobacterium species pathogenic for humans. due to its rare presentation, physicians often ignore the importance of this pathogen. we report a fulminant fatal case of bacteremia in a 38-year-old colombian man. the clinical manifestations were fever, thoracic pain, respiratory failure and death. his condition, from the beginning of clinical diagnosis, went into continuous deterioration, till his death, withi ...200717874003
[chromobacterium violaceum septicemia: first case report in the french west indies].we report a fatal case of chromobacterium violaceum septicemia in a 42-year-old farm worker living in the french west indies. the bacteria found in the muddy soil and the stagnant water of tropical and subtropical regions is rarely a source of human infection.200717905550
biosynthesis of violacein: a genuine intermediate, protoviolaceinic acid, produced by vioabde, and insight into vioc function.a biosynthetic intermediate of violacein produced by the mixed enzymes of vioabde was elucidated to be 5-(5-hydroxy-1h-indol-3-yl)-3-(1h-indol-3-yl)-1h-pyrrole-2-carboxylic acid, named protoviolaceinic acid, indicating that vioc, responsible for the final biosynthetic step, works to oxygenate at the 2-position of the right side indole ring, and that the oxygenation reaction to form the central pyrrolidone core proceeds in a non-enzymatic fashion.200717925955
violacein: properties and biological activities.the violet pigment violacein is an indole derivative, isolated mainly from bacteria of the genus chromobacterium, which exhibits important antitumoral, antimicrobial and antiparasitary properties. furthermore, the formulation of violacein in different polymeric carriers developed so far offers alternative approaches to overcoming physiological barriers and undesirable physicochemical properties in vivo, thus improving its efficacy.200717927569
n-acyl homoserine lactones are degraded via an amidolytic activity in comamonas sp. strain d1.comamonas strain d1 enzymatically inactivates quorum-sensing (qs) signal molecules of the n-acyl homoserine lactone (n-ahsl) family, and exhibits the broadest inactivation range of known bacteria. it degrades n-ahsl with acyl-side chains ranging from 4 to 16 carbons, with or without 3-oxo or 3-hydroxy substitutions. n-ahsl degradation yields hsl but not n-acyl homoserine: strain d1 therefore harbors an amidohydrolase activity. strain d1 is the fifth bacterium species in which an n-ahsl amidohydr ...200717136382
the serratia-type hemolysin of chromobacterium violaceum.chromobacterium violaceum is a gram-negative opportunistic human pathogen and an inhabitant of tropical soils and waterways. although known primarily for the synthesis of the pigment violacein, and more recently as a reporter strain for quorum sensing, clinical reports of chromobacteriosis comprise the largest block of published literature on this organism. genome sequencing has revealed many potential virulence factors in this microorganism, and this paper establishes the presence in c. violace ...200717169000
isolation and characterization of two groups of novel marine bacteria producing violacein.thirteen strains of novel marine bacteria producing a purple pigment were isolated from the pacific coast of japan. they were divided into two groups based on their 16s ribosomal rna gene sequences, and both groups of bacteria belonged to the genus pseudoalteromonas. the uv-visible spectrum of the pigment was identical to those of violacein, a pigment produced by several species of bacteria including chromobacterium violaceum, an opportunistic pathogen. further analysis of the chemical structure ...200817968625
a study of natural attenuation processes involved in a microcosm model of a crude oil-impacted wetland sediment in the niger delta.sediment sample from a previously impacted ochani stream was recreated in four glass chambers (a-d) as microcosms. the aim was to model and compare natural attenuation processes to forced aeration for remediation of a crude oil-impacted ecosystem. the initial hydrocarbon concentration was 90,212 mg/kg of sediment. after 60 days, the natural attenuation processes of photooxidation, evaporation, volatilization and biodegradation accounted for 31.9% of the total hydrocarbon removed while 13% was at ...200817988860
the violacein biosynthetic enzyme vioe shares a fold with lipoprotein transporter proteins.vioe, an unusual enzyme with no characterized homologues, plays a key role in the biosynthesis of violacein, a purple pigment with antibacterial and cytotoxic properties. without bound cofactors or metals, vioe, from the bacterium chromobacterium violaceum, mediates a 1,2 shift of an indole ring and oxidative chemistry to generate prodeoxyviolacein, a precursor to violacein. our 1.21 a resolution structure of vioe shows that the enzyme shares a core fold previously described for lipoprotein tran ...200818171675
crystal structure of vioe, a key player in the construction of the molecular skeleton of violacein.violacein and the indolocarbazoles are naturally occurring bisindole products with various biological activities, including antitumor activity. although these compounds have markedly different molecular skeletons, their biosynthetic pathways share the same intermediate "compound x," which is produced from l-tryptophan via indole-3-pyruvic acid imine. compound x is a short-lived intermediate that is spontaneously converted to chromopyrrolic acid for indolocarbazole biosynthesis, whereas vioe tran ...200818171677
paludibacterium yongneupense gen. nov., sp. nov., isolated from a wetland, yongneup, in korea.a cream-coloured bacterial strain, 5yn8-15(t), was isolated from a wetland, yongneup, in the inje region of the republic of korea. the bacterium was facultatively anaerobic, gram-negative, motile with a single polar flagellum and curved-rod-shaped. based on 16s rrna gene sequence analysis, strain 5yn8-15(t) is a member of the betaproteobacteria. closely related taxa were gulbenkiania mobilis e4fc31(t) (94.9% sequence similarity), chromobacterium species (94.1-94.4%), aquitalea magnusonii tro-001 ...200818175708
n-acylhomoserine lactone regulates violacein production in chromobacterium violaceum type strain atcc tests, chromobacterium violaceum atcc 12472 produced several n-acyl-l-homoserine lactones (ahls). of these, n-(3-hydroxydecanoyl)-l-homoserine lactone was dominant, and controlled violacein production by quorum sensing. strain vir07, an ahl-deficient mutant, did not produce violacein. violacein production in vir07 was induced by adding long-chain ahls (c10-c16), but was inhibited by adding short-chain ahls (c4-c8). strain vir07 showed the response of violacein production when ahls diffused fr ...200818177311
diversity and quorum-sensing signal production of proteobacteria associated with marine sponges.marine sponges are hosts to diverse and dense bacterial communities and thus provide a potential environment for quorum sensing. quorum sensing, a key factor in cell-cell communication and bacterial colonization of higher animals, might be involved in the symbiotic interactions between bacteria and their sponge hosts. given that marine proteobacteria are known to produce n-acyl homoserine lactone (ahl) signal molecules, we tested the production of ahls by alpha- and gammaproteobacteria isolated ...200818211268
structural basis for mannose recognition by a lectin from opportunistic bacteria burkholderia cenocepacia.chronic colonization of the lungs by opportunist bacteria such as pseudomonas aeruginosa and members of the bcc (burkholderia cepacia complex) is the major cause of morbidity and mortality among cf (cystic fibrosis) patients. pa-iil (lecb gene), a soluble lectin from ps. aeruginosa, has been the subject of much interest because of its very strong affinity for fucose. orthologues have been identified in the opportunist bacteria ralstonia solanacearum, chromobacterium violaceum and burkholderia of ...200818215132
improved activity of enzymes in mixed cationic reverse micelles with imidazolium-based surfactants.this work reports the significant enhancement in performance of interfacially active enzymes, chromobacterium viscosum (cv) lipase and horseradish peroxidase (hrp) in mixed reverse micelles of cetyltrimethylammonium bromide (ctab) and imidazolium-based amphiphiles having varying tail lengths. lipase activity in these mixed systems was always higher than that in the individual cationic reverse micelles of ctab or any imidazolium surfactant, highest being observed in the mixed system of ctab (50 m ...200818067868
diversity in antifungal activity of strains of chromobacterium violaceum from the brazilian amazon.chromobacterium violaceum is a free-living gram-negative bacterium found in soil and aquatic habitats; abundantly present in the brazilian amazon, it is an important example of exploitable microbial diversity of the tropics. in this study, 24 strains from the brazilian amazon and atcc 12472(t) were investigated for biocontrol potential of seven fungi pathogenic to soybean [glycine max (l.) merril] seed. both cells and the supernatants of two brazilian strains, 07-1 and 27-1, together with atcc 1 ...200818347828
bacteria flora and heavy metals in cultivated oysters crassostrea iredalei of setiu wetland, east coast peninsular malaysia.slipper oyster crassostrea iredalei is a species of good demand for its sweet flavor and white coloured flesh. the filter feeding nature predisposes oysters to accumulation of pathogenic and heavy metals in waters impacted by sewage pollutions and may thus render the oysters unfit for human consumption. a study was undertaken to investigate the presence of bacteria flora and heavy metal concentrations in cultivated oysters crassostrea iredalei at setiu wetland, terengganu, the only source of cul ...200818369732
prevalence of bacterial pathogens and their anti-microbial resistance in tilapia and their pond water in trinidad, tilapia (oreonchromis spp.) is one of the most important fresh water food fish and the number of farms has been increasing annually. a study was conducted in the local tilapia industry to determine the microbial quality of pond water, prevalence of bacterial pathogens and their anti-microbial resistance using the disk diffusion method. seventy-five apparently healthy fish and 15 pond water samples from three of the four commercial tilapia fish farms in the country were processed. th ...200818387142
gene expression of the arsenic resistance operon in chromobacterium violaceum atcc 12472.chromobacterium violaceum atcc 12472 presents an arsrcb-type operon, which is involved in arsenic resistance. the regulating protein of this resistance system (arsr) does not have the small conserved site (elcvdcl) to link to the metalloid, as observed in escherichia coli, and is thus considered to be an atypical arsr protein, like that observed in acidithiobacillus ferrooxidans. in the present study, the gene expression profile of the ars operon under induction at different concentrations of ar ...200818388983
chromobacterium aquaticum sp. nov., isolated from spring water samples.strain cc-seya-1t, a motile, gram-negative, non-violet-pigmented bacterium, was isolated on nutrient agar from spring-water samples collected from yang-ming mountain, taipei county, taiwan. 16s rrna gene sequence studies showed that the strain clustered with chromobacterium violaceum (96.8 % similarity) and chromobacterium subtsugae (96.5 % similarity), followed by aquitalea magnusonii (95.8 % similarity). the fatty acid profile was slightly different from those reported for c. violaceum, c. sub ...200818398186
degradation of n-acyl homoserine lactone quorum sensing signal molecules by forest root-associated fungi.a collection of mycorrhizal and nonmycorrhizal root-associated fungi coming from forest environments was screened for their ability to degrade n-acyl homoserine lactones (ahl) or to prevent ahl recognition by producing quorum sensing inhibitors (qsi). no production of qs-inhibitors or -activators was detected using the two biosensors chromobacterium violaceum cv026 and agrobacterium tumefaciens in the culture supernatant of these fungi. however, the ability to degrade c6- and 3o,c6-hsl was detec ...200818400006
ppsy: a vector for the stable cloning and expression of streptomycete single gene phenotypes in escherichia coli.ppsy is a 12kb cloning vector derived from the incw plasmid r388, which provides a rapid and easy way to stably clone phenotypes encoded in dna segments <10kb. in the present study three different genes were amplified by pcr, cloned into pgem-t easy and sub-cloned into the ecori site of ppsy. the first gene, vioa, is a fad-dependent l-tryptophan amino acid oxygenase from the high g+c gram-negative bacterium chromobacterium violaceum. vioa is involved in the synthesis of the indolocarbazole antit ...200818406459
kinetics of thermal unfolding of phenylalanine hydroxylase variants containing different metal cofactors (feii, coii, and znii) and their isokinetic relationship.the kinetics of thermal unfolding of apo- and holo-chromobacterium violaceum phenylalanine hydroxylase (cpah) was investigated using circular dichroism (cd) over the temperature range 44-76 degrees c. in addition to the native cofactor (feii), the unfolding kinetics of holo-cpah was characterized using znii and coii as cofactors. kinetic profiles for apo- and holo-cpah showed a single-phase exponential rise in the cd signal at lambda=222 nm and a first-order dependence on protein concentration. ...200818433092
chromobacterium violaceum cellulitis and sepsis following cutaneous marine trauma.chromobacterium violaceum is a gram-negative bacillary organism that characteristically produces the purple pigment violacein. documented as the cause of clinically relevant human infections in only 35 cases in the united states, c violaceum is particularly seen in patients with a history of cutaneous injury or trauma. we report the case of an 18-year-old woman who was struck by a propeller in a boating accident and sustained multiple deep lacerations of her right lower extremity. shortly after ...200818441852
neonatal septicaemia in calabar, nigeria.a three-year survey of neonatal septicaemia (363 bacteriologically proven cases) in the university of calabar teaching hospital, calabar, has demonstrated that the dominant blood isolate was staphylococcus aureus (53%) followed by unclassified coliforms (20%), an unexpected chromobacterium violaceum (5%). the incidence of neonatal septicaemia was 54.9 per 1000 live births for inborn infants. the predominant organisms were largely susceptible to gentamicin, ceftriazone and cefuroxime with a morta ...200818453516
hydrogen peroxide linked to lysine oxidase activity facilitates biofilm differentiation and dispersal in several gram-negative bacteria.the marine bacterium pseudoalteromonas tunicata produces an antibacterial and autolytic protein, alpp, which causes death of a subpopulation of cells during biofilm formation and mediates differentiation, dispersal, and phenotypic variation among dispersal cells. the alpp homologue (loda) in the marine bacterium marinomonas mediterranea was recently identified as a lysine oxidase which mediates cell death through the production of hydrogen peroxide. here we show that alpp in p. tunicata also act ...200818502869
purification and characterization of chromobacterium sp. ds-1 cholesterol oxidase with thermal, organic solvent, and detergent tolerance.a new screening method for 6beta-hydroperoxycholest-4-en-3-one (hceo)-forming cholesterol oxidase was devised in this study. as the result of the screening, a novel cholesterol oxidase producer (strain ds-1) was isolated and identified as chromobacterium sp. extracellular cholesterol oxidase of strain ds-1 was purified from the culture supernatant. the molecular mass of the purified enzyme was 58 kda. this enzyme showed a visible adsorption spectrum having peaks at 355 and 450 nm, like a typical ...200818512056
lipases at interfaces: unique interfacial properties as globular proteins.the adsorption behavior of two globular proteins, lipase from rhizomucor miehei and beta-lactoglobulin, at inert oil/water and air/water interfaces was studied by the pendant drop technique. the kinetics and adsorption isotherms were interpreted for both proteins in different environments. it was found that the adopted mathematical models well describe the adsorption behavior of the proteins at the studied interfaces. one of the main findings is that unique interfacial properties were observed f ...200818512870
chromobacterium haemolyticum sp. nov., a strongly haemolytic species.a gram-negative bacterium, strain mda0585(t), isolated from a sputum culture, was characterized by a polyphasic approach. the 16s rrna gene and a conserved portion of the dna gyrase a gene were sequenced and analysed phylogenetically. strain mda0585(t) showed the closest relationships with chromobacterium violaceum atcc 12472(t) and chromobacterium subtsugae praa4-1(t) (96.1 % and 96.3 % 16s rrna gene sequence similarity, respectively). the cellular fatty acids of strain mda0585(t) consisted mai ...200818523185
the 1.25 a resolution structure of phosphoribosyl-atp pyrophosphohydrolase from mycobacterium tuberculosis.phosphoribosyl-atp pyrophosphohydrolase is the second enzyme in the histidine-biosynthetic pathway, irreversibly hydrolyzing phosphoribosyl-atp to phosphoribosyl-amp and pyrophosphate. it is encoded by the hise gene, which is present as a separate gene in many bacteria and archaea but is fused to hisi in other bacteria, fungi and plants. because of its essentiality for growth in vitro, hise is a potential drug target for tuberculosis. the crystal structures of two native (uncomplexed) forms of h ...200818560150
human chromobacterium violaceum infection in southeast asia: case reports and literature review.chromobacterium violaceum infection in humans is a rare tropical and subtropical disease. the awareness of this organism is limited in spite its ubiquitous distribution. several cases have been reported from southeast asia. a localized infection followed by an overwhelming septicemia and metastatic lesions is the usual pattern of this illness. optimal antimicrobial treatment and duration are unknown. consequently, the outcome is usually fatal. the study reported two patients who suffered from fu ...200818564684
rapid hydrolysis of quorum-sensing molecules in the gut of lepidopteran larvae.microorganisms compete for nutrients and living space in the gut of plant-feeding insect larvae, such as spodoptera spp. their physiological activities and their organization are generally controlled or synchronised by "autoinducers", such as n-acylhomoserinelactones (ahls). due to the strongly alkaline milieu in the insect gut, the lactone ring of ahls is rapidly and spontaneously opened. further degradation to the inactive components homoserine and the acyl moiety is then achieved by a microbi ...200818642255
inhibition of bacterial quorum sensing-regulated behaviors by tremella fuciformis extract.quorum sensing (qs), or the control of gene expression in response to cell density, is used by both gram-negative and gram-positive bacteria to regulate a variety of physiological functions. increasing evidence implies that certain eukaryotes produce qs-inhibitory compounds. in this work, we tested tremella fuciformis for their ability to inhibit qs-regulated behaviors. t. fuciformis fruiting bodies were dried and extracted using 75% (v/v) aqueous methanol. the crude extract was redissolved in a ...200818661179
antibacterial activity of halogenated sesquiterpenes from malaysian laurencia spp.during our studies on malaysian laurencia species, brominated metabolites, tiomanene, acetylmajapolene b, and acetylmajapolene a were isolated from an unrecorded species collected at pulau tioman, pahang along with known majapolene b and majapolene a. acetylmajapolene a was a mixture of diastereomers as in the case of majapolene a. tiomanene may be a plausible precursor for acetylmajapolenes b and a. in addition, three known halogenated sesquiterpenes and two known halogenated c(15) acetogenins ...200818718619
polyhydroxyalkanoate (pha) production using waste vegetable oil by pseudomonas sp. strain produce polyhydroxyalkanoate (pha) from inexpensive substrates by bacteria, vegetable-oil-degrading bacteria were isolated from a rice field using enrichment cultivation. the isolated pseudomonas sp. strain dr2 showed clear orange or red spots of accumulated pha granules when grown on phosphate and nitrogen limited medium containing vegetable oil as the sole carbon source and stained with nile blue a. up to 37.34% (w/w) of intracellular pha was produced from corn oil, which consisted of three ...200818756101
fatal wound infection caused by chromobacterium violaceum in ho chi minh city, vietnam.chromobacterium violaceum is a proteobacterium found in soil and water in tropical regions which rarely causes infection in humans. here, we report a fatal bacteremia caused by chromobacterium violaceum in vietnam. we describe a number of clinical, microbiological, and molecular aspects associated with this bacterial infection.200818799697
successful treatment of chromobacterium violaceum sepsis in south africa.chromobacterium violaceum sepsis is extremely rare and usually fatal. a very few cases of c. violaceum infection have been reported from africa, but never from south africa. as far as could be ascertained, this infection has never been reported in a patient with leukaemia. we describe what we believe to be the first such case of c. violaceum sepsis, in a 16-year-old female patient with acute biphenotypic leukaemia, which developed during the neutropenic phase after intensive chemotherapy. the in ...200818809561
kinetic isotope effects on aromatic and benzylic hydroxylation by chromobacterium violaceum phenylalanine hydroxylase as probes of chemical mechanism and reactivity.phenylalanine hydroxylase from chromobacterium violaceum (cvpheh) is a non-heme iron monooxygenase that catalyzes the hydroxylation of phenylalanine to tyrosine. in this study, we used deuterium kinetic isotope effects to probe the chemical mechanisms of aromatic and benzylic hydroxylation to compare the reactivities of bacterial and eukaryotic aromatic amino acid hydroxylases. the (d) k cat value for the reaction of cvpheh with [(2)h 5]phenylalanine is 1.2 with 6-methyltetrahydropterin and 1.4 ...200818817418
cellulose biosynthesis by the beta-proteobacterium, chromobacterium violaceum.the chromobacterium violaceum atcc 12472 genome was sequenced by the brazilian national genome project consortium. previous annotation reported the presence of cellulose biosynthesis genes in that genome. analysis of these genes showed that, as observed in other bacteria, they are organized in two operons. in the present work, experimental evidences of the presence of cellulose in the extracellular matrix of the biofilm produced by c. violaceum in static cultures are shown. biofilm samples were ...200818820969
pseudogulbenkiania subflava gen. nov., sp. nov., isolated from a cold spring.a yellow-coloured bacterial strain, designated bp-5(t), was isolated from a water sample of a cold spring located in the hsinchu area of northern taiwan. cells of the strain were gram-negative, non-spore-forming rods with a polar flagellum. the isolate was able to grow at 15-42 degrees c, 0-1 % nacl and ph 6-8. the predominant fatty acids were summed feature 3 (c(16 : 1)omega7c and/or iso-c(15 : 0) 2-oh), c(16 : 0) and c(18 : 1)omega7c. the major respiratory quinone was ubiquinone 8. the dna g+c ...200818842860
amphibian chemical defense: antifungal metabolites of the microsymbiont janthinobacterium lividum on the salamander plethodon cinereus.disease has spurred declines in global amphibian populations. in particular, the fungal pathogen batrachochytrium dendrobatidis has decimated amphibian diversity in some areas unaffected by habitat loss. however, there is little evidence to explain how some amphibian species persist despite infection or even clear the pathogen beyond detection. one hypothesis is that certain bacterial symbionts on the skin of amphibians inhibit the growth of the pathogen. an antifungal strain of janthinobacteriu ...200818949519
anthranilate synthase subunit organization in chromobacterium violaceum.tryptophan is an aromatic amino acid used for protein synthesis and cellular growth. chromobacterium violaceum atcc 12472 uses two tryptophan molecules to synthesize violacein, a secondary metabolite of pharmacological interest. the genome analysis of this bacterium revealed that the genes trpa-f and paba-b encode the enzymes of the tryptophan pathway in which the first reaction is the conversion of chorismate to anthranilate by anthranilate synthase (as), an enzyme complex. in the present study ...200818949702
diversity of chromobacterium violaceum isolates from aquatic environments of state of pará, brazilian amazon.the present study intended to characterize the phenotypic and genetic diversity of brazilian isolates of chromobacterium violaceum from aquatic environments within the amazon region. nineteen isolates showed morphological properties of c. violaceum and the majority grew at 44 degrees c. low temperatures, in contrast, showed to be inhibitory to their growth, as eleven isolates did not grow at 10 degrees c and nine did not produce pigmentation, clearly indicating an inhibition of their metabolism. ...200819057818
chromobacterium violaceum infection in a provincial hospital in sri lanka. 200819189802
recurrent chromobacterium violaceum infection in a patient with chronic granulomatous disease.we report a rare case of recurrent infection of chromobacterium violaceum in an immunocompromised patient. despite the high mortality rate associated with this infection as reported in the literature, this patient survived three episodes of recurrent infection. we believe that with high clinical suspicion, prompt treatment and appropriate antimicrobial agents, it is possible for clinicians to treat this infection effectively and reduce the mortality rate.200819385503
oxidative dna damage protective activity, antioxidant and anti-quorum sensing potentials of moringa oleifera.the aqueous extract of leaf (le), fruit (fe) and seed (se) of moringa oleifera was assessed to examine the ability to inhibit the oxidative dna damage, antioxidant and anti-quorum sensing (qs) potentials. it was found that these extracts could significantly inhibit the oh-dependent damage of puc18 plasmid dna and also inhibit synergistically with trolox, with an activity sequence of le > fe > se. hplc and ms/ms analysis was carried out, which showed the presence of gallic acid, chlorogenic acid, ...200919425184
a probable aculeacin a acylase from the ralstonia solanacearum gmi1000 is n-acyl-homoserine lactone acylase with quorum-quenching activity.the infection and virulence functions of diverse plant and animal pathogens that possess quorum sensing systems are regulated by n-acylhomoserine lactones (ahls) acting as signal molecules. ahl-acylase is a quorum quenching enzyme and degrades ahls by removing the fatty acid side chain from the homoserine lactone ring of ahls. this blocks ahl accumulation and pathogenic phenotypes in quorum sensing bacteria.200919426552
the origin of the electrostatic perturbation in acetoacetate decarboxylase.acetoacetate decarboxylase (aadase) has long been cited as the prototypical example of the marked shifts in the pk(a) values of ionizable groups that can occur in an enzyme active site. in 1966, it was hypothesized that in aadase the origin of the large pk(a) perturbation (-4.5 log units) observed in the nucleophilic lys 115 results from the proximity of lys 116, marking the first proposal of microenvironment effects in enzymology. the electrostatic perturbation hypothesis has been demonstrated ...200919458715
structural basis for the erythro-stereospecificity of the l-arginine oxygenase vioc in viomycin biosynthesis.the nonheme iron oxygenase vioc from streptomyces vinaceus catalyzes fe(ii)-dependent and alpha-ketoglutarate-dependent cbeta-hydroxylation of l-arginine during the biosynthesis of the tuberactinomycin antibiotic viomycin. crystal structures of vioc were determined in complexes with the cofactor fe(ii), the substrate l-arginine, the product (2s,3s)-hydroxyarginine and the coproduct succinate at 1.1-1.3 a resolution. the overall structure reveals a beta-helix core fold with two additional helical ...200919490124
characteristics and biotechnological applications of microbial cholesterol oxidases.microbial cholesterol oxidase is an enzyme of great commercial value, widely employed by laboratories routinely devoted to the determination of cholesterol concentrations in serum, other clinical samples, and food. in addition, the enzyme has potential applications as a biocatalyst which can be used as an insecticide and for the bioconversion of a number of sterols and non-steroidal alcohols. the enzyme has several biological roles, which are implicated in the cholesterol metabolism, the bacteri ...200919495743
an fad-dependent pyridine nucleotide-disulfide oxidoreductase is involved in disulfide bond formation in fk228 anticancer depsipeptide.disulfide bonds are rare in bacterial natural products, and the mechanism of disulfide bond formation in those products is unknown. here we characterize a gene and its product critical for a disulfide bond formation in fk228 anticancer depsipeptide in chromobacterium violaceum. deletion of deph drastically reduced fk228 production, whereas complementation of the deph-deletion mutant with a copy of deph on a medium copy-number plasmid not only fully restored the fk228 production but also signific ...200919549597
synthesis, nematicidal and antimicrobial properties of bis-[4-methoxy-3-[3-(4-fluorophenyl)-6-(4-methylphenyl)-2(aryl)-tetrahydro-2h-pyrazolo[3,4-d]thiazol-5-yl]phenyl]methanes.a new series of bis-[4-methoxy-3-[3-(4-fluorophenyl)-6-(4-methylphenyl)-2-(aryl)-3,3a,5,6-tetrahydro-2h-pyrazolo[3,4-d][1,3]thiazol-5-yl]phenyl]methanes 6a-r was synthesized by the reaction of arylidine derivative of methylene-bis-thiazolidinones 5a-c with aryl/alkyl hydrazines. chemical structures of all the new compounds were established by ir, (1)h-nmr, (13)c-nmr, ms and elemental data. the compounds 6a-r were evaluated for their nematicidal activity against ditylenchus myceliophagus and caen ...200919571412
blocking of pseudomonas aeruginosa and ralstonia solanacearum lectins by plant and microbial branched polysaccharides used as food additives.pseudomonas aeruginosa antibiotic resistance prompted the search for glycodecoys that would block its lectin-dependent adhesion to human cells. we have used the lectins of this pathogen, pa-il (galactophilic leca) and pa-iil (fucophilic lecb), and two additional pathogenic bacterial lectins, cv-iil (fucophilic, of chromobacterium violaceum) and rs-iil (mannophilic, of ralstonia solanacearum), for assaying the pathogenic lectin-blocking abilities of some plant and microbial polysaccharidic food a ...200919572540
species distribution and antimicrobial susceptibility of gram-negative aerobic bacteria in hospitalized cancer patients.nosocomial infections pose significant threats to hospitalized patients, especially the immunocompromised ones, such as cancer patients.200919228413
is gas-discharge plasma a new solution to the old problem of biofilm inactivation?conventional disinfection and sterilization methods are often ineffective with biofilms, which are ubiquitous, hard-to-destroy microbial communities embedded in a matrix mostly composed of exopolysaccharides. the use of gas-discharge plasmas represents an alternative method, since plasmas contain a mixture of charged particles, chemically reactive species and uv radiation, whose decontamination potential for free-living, planktonic micro-organisms is well established. in this study, biofilms wer ...200919246743
violacein extracted from chromobacterium violaceum inhibits plasmodium growth in vitro and in vivo.violacein is a violet pigment extracted from the gram-negative bacterium chromobacterium violaceum. it presents bactericidal, tumoricidal, trypanocidal, and antileishmanial activities. we show that micromolar concentrations efficiently killed chloroquine-sensitive and -resistant plasmodium falciparum strains in vitro; inhibited parasitemia in vivo, even after parasite establishment; and protected plasmodium chabaudi chabaudi-infected mice from a lethal challenge.200919273690
chromobacterium violaceum endocarditis and hepatic abscesses treated successfully with meropenem and ciprofloxacin.chromobacterium violaceum infection is uncommon but potentially fatal, with a clinical picture similar to melioidosis but with different antibiotic sensitivities and treatment. this infection can involve any organ, but we believe this is the first reported case of c. violaceum endocarditis.200919351314
comparative metagenomics of daphnia symbionts.shotgun sequences of dna extracts from whole organisms allow a comprehensive assessment of possible symbionts. the current project makes use of four shotgun datasets from three species of the planktonic freshwater crustaceans daphnia: one dataset from clones of d. pulex and d. pulicaria and two datasets from one clone of d. magna. we analyzed these datasets with three aims: first, we search for bacterial symbionts, which are present in all three species. second, we search for evidence for cyanob ...200919383155
secondary metabolites produced by the marine bacterium halobacillus salinus that inhibit quorum sensing-controlled phenotypes in gram-negative bacteria.certain bacteria use cell-to-cell chemical communication to coordinate community-wide phenotypic expression, including swarming motility, antibiotic biosynthesis, and biofilm production. here we present a marine gram-positive bacterium that secretes secondary metabolites capable of quenching quorum sensing-controlled behaviors in several gram-negative reporter strains. isolate c42, a halobacillus salinus strain obtained from a sea grass sample, inhibits bioluminescence production by vibrio harve ...200919060172
septicemia in a neonatal calf associated with chromobacterium violaceum.chromobacterium violaceum infections are highly fatal and rarely reported in domestic animals. this report describes a fatal case of c. violaceum septicemia in a 7-day-old female beef calf. the calf had necrosuppurative omphalophlebitis, necrotizing interstitial pneumonia, necrosuppurative hepatitis and splenitis, anterior uveitis with hypopyon, suppurative polyarthritis, and disseminated hemorrhagic meningitis with multifocal necrotizing encephalitis. histologically, clusters of gram-negative b ...200919112118
enhanced production of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer with manipulated variables and its properties.cupriavidus sp. usmaa1020, a local isolate was able to biosynthesis poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [p(3hb-co-4hb)] copolymer with various 4hb precursors as the sole carbon source. manipulation of the culture conditions such as cell concentration, phosphate ratio and culture aeration significantly affected the synthesis of p(3hb-co-4hb) copolymer and 4hb composition. p(3hb-co-4hb) copolymer with 4hb compositions ranging from 23 to 75 mol% 4hb with various mechanical and thermal prop ...200919189144
cloning, sequence analysis, and expression of a gene encoding chromobacterium sp. ds-1 cholesterol oxidase.chromobacterium sp. strain ds-1 produces an extracellular cholesterol oxidase that is very stable at high temperatures and in the presence of organic solvents and detergents. in this study, we cloned and sequenced the structural gene encoding the cholesterol oxidase. the primary translation product was predicted to be 584 amino acid residues. the mature product is composed of 540 amino acid residues. the amino acid sequence of the product showed significant similarity (53-62%) to the cholesterol ...200919015844
culturable heterotrophic bacteria in seawater and mytilus galloprovincialis from a mediterranean area (northern ionian sea-italy).although mar piccolo of taranto (ionian sea, italy) is one of the most important mytilus galloprovincialis farming areas, data concerning the natural bacterial microbiota of these mussels and their surrounding environment are still scant. this study was carried out seasonally, throughout a year, to determine culturable heterotrophic bacteria both in the water and mussels samples collected at three sampling sites in the northern ionian sea: s. vito, lido gandoli and lido silvana. culturable heter ...200918301997
distribution of n-acylhomoserine lactone-producing fluorescent pseudomonads in the phyllosphere and rhizosphere of potato (solanum tuberosum l.).four hundred and fifty nine isolates of fluorescent pseudomonads were obtained from the leaves and roots of potato plants. of these, 20 leaf isolates and 28 root isolates induced violacein production in two n-acylhomoserine lactone (ahl)-reporter strains-chromobacterium violaceum cv026 and vir24. vir24 is a new reporter strain for long n-acyl-chain-homoserine lactones, which can not be detected by cv026. thin-layer chromatography revealed that the isolates produced multiple ahl molecules. we com ...200921566390
computational analysis suggests that virulence of chromobacterium violaceum might be linked to biofilm formation and poly-nag biosynthesis.groups of genes that produce exopolysaccharide with a n-acetyl-d-glucosamine monomer are in the genome of several pathogenic bacteria. chromobacterium violaceum, an opportunistic pathogen, has the operon hmshfr-cv2940, whose proteins can synthesize such polysaccharide. in this work, multiple alignments among proteins from bacteria that synthesize such polysaccharide were used to verify the existence of amino acids that might be critical for pathogen activity. three-dimensional models were genera ...200921637531
chromobacterium piscinae sp. nov. and chromobacterium pseudoviolaceum sp. nov., from environmental samples.two strains (lmg 3947 and lmg 3953) of motile, gram-negative, violet-pigmented bacteria, respectively isolated in 1972 and before 1953 from environmental samples and previously assigned to chromobacterium violaceum, were studied again in detail for their taxonomic position. 16s rrna gene sequence analysis showed that both strains clustered together with the type strain of chromobacterium violaceum (99.8 % sequence similarity for strain lmg 3953(t) and 98.9 % sequence similarity for lmg 3947(t)). ...200919622653
inhibition of quorum sensing regulated bacterial functions by plant essential oils with special reference to clove evaluate quorum sensing (qs) inhibitory activity of plant essential oils using strains of chromobacterium violaceum (cv12472 and cvo26) and pseudomonas aeruginosa (pao1).200919627477
fatal chromobacterium violaceum septicaemia in northern laos, a modified oxidase test and post-mortem forensic family g6pd analysis.chromobacterium violaceum is a gram negative facultative anaerobic bacillus, found in soil and stagnant water, that usually has a violet pigmented appearance on agar culture. it is rarely described as a human pathogen, mostly from tropical and subtropical areas.200919640274
a quorum-sensing antagonist targets both membrane-bound and cytoplasmic receptors and controls bacterial pathogenicity.quorum sensing is a process of bacterial communication involving production and detection of secreted molecules called autoinducers. gram-negative bacteria use acyl-homoserine lactone (ahl) autoinducers, which are detected by one of two receptor types. first, cytoplasmic luxr-type receptors bind accumulated intracellular ahls. ahl-luxr complexes bind dna and alter gene expression. second, membrane-bound luxn-type receptors bind accumulated extracellular ahls. ahl-luxn complexes relay information ...200919647512
enhancement of l-tryptophan 5-hydroxylation activity by structure-based modification of l-phenylalanine 4-hydroxylase from chromobacterium violaceum.the objective of this study was to enhance l-tryptophan hydroxylation activity of l-phenylalanine 4-hydroxylase. it had been known that l-phenylalanine 4-hydroxylase from chromobacterium violaceum could convert l-tryptophan to 5-hydroxy-l-tryptophan and l-phenylalanine to l-tyrosine; however, the activity for l-tryptophan was extremely low compared to l-phenylalanine activity levels. we used the information on the crystal structures of aromatic amino acid hydroxylases to generate c. violaceuml-p ...200919664549
tocopherol, carotene, phenolic contents and antibacterial properties of rose essential oil, hydrosol and absolute.the antioxidant and antibacterial activities, and total phenolic contents of rosa damascena mill. flower extracts (absolute, essential oil and hydrosol) were investigated. the chemical compositions of these extracts were analysed by gc-ms. phenylethyl alcohol (78.38%) was found to be the main constituent of rose absolute, while citrenellol and geraniol were the major compounds (>55%) of rose essential oil and hydrosol. tocopherol and carotene levels were determined by high performance liquid chr ...200919688375
anti-diarrhoeal and ulcer-protective effects of violacein isolated from chromobacterium violaceum in wistar rats.violacein was isolated from chromobacterium violaceum, a soil gram-negative bacterium collected from the forest water body soil sample from kolli hills of tamil nadu, india. in the present study the anti-diarrhoeal and ulcer-protective properties of violacein were investigated in wistar rats using castor oil, magnesium sulphate and ethanol. the intestinal transit in rats was significantly (p < 0.001) reduced and gastric emptying was delayed; 40 mg/kg of violacein elicited a greater anti-motility ...200919709325
quorum sensing inhibition activity of garlic extract and p-coumaric acid.the goal of this work was to investigate the influence of dmso, garlic extract and p-coumaric acid on bacterial quorum sensing (qs).200919709367
chromobacterium violaceum sepsis in an infant.chromobacterium violaceum is a rare pathogen that can cause potentially fatal infections in humans. till date, 150 cases are reported worldwide including 7 from india. we report a 6 month old infant who presented with high grade fever, respiratory distress and multiple vesicular skin lesions. chromobacterium violaceum was isolated from blood, bone marrow aspirate and from skin lesions. infant responded to treatment with piperacillin and ciprofloxacin, and is doing well on follow up.200919717863
efficient synthesis and evaluation of quorum-sensing modulators using small molecule macroarrays.a method for the synthesis of small molecule macroarrays of n-acylated l-homoserine lactones (ahls) is reported. a focused library of ahls was constructed, and the macroarray platform was found to be compatible with both solution and agar-overlay assays using quorum-sensing (qs) reporter strains. several qs antagonists were discovered and serve to showcase the macroarray as a straightforward technique for qs research.200919743816
[cloning of phzir from the endophytic pseudomonas sp. g5 and its expression in escherichia coli].we isolated a new strain of endophytic pseudomonas g5 from the stems of chinese parsley (coriandrum sativum l.), and it is tentatively identified as pseudomonas aurantiaca according to analysis of the entire substrate utilization profiles using biolog microstation system (biolog, inc, hayward ca). an array of evidence established that many gram-negative bacteria employ quorum sensing (qs) system to regulate gene expression in response to cell density using small diffusible signal molecules, n-ac ...200919777809
microbial growth and quorum sensing antagonist activities of herbal plants extracts.antimicrobial and antiquorum sensing (aqs) activities of fourteen ethanolic extracts of different parts of eight plants were screened against four gram-positive, five gram-negative bacteria and four fungi. depending on the plant part extract used and the test microorganism, variable activities were recorded at 3 mg per disc. among the grampositive bacteria tested, for example, activities of laurus nobilis bark extract ranged between a 9.5 mm inhibition zone against bacillus subtilis up to a 25 m ...200919783935
chromobacterium violaceum endocarditis and hepatic abscesses treated successfully with meropenem and ciprofloxacin. 200919807647
nanocytotoxicity: violacein and violacein-loaded poly (d, l-lactide-co-glycolide) nanoparticles acting on human leukemic cells.violacein is a compound obtained from chromobacterium violaceum, a bacterium found in the amazonian region. violacein-loaded poly (d, l-lactide-co-glycolide) nanoparticles has a similar inhibitory effect evaluated by trypan blue assay on leukemic hl60 cells than the free form. however, the cytotoxic effects evaluated by phosphatase activity and mtt reduction assays were lower for the encapsulated form than for free violacein. based on morphological changes, violacein and violacein entrapped in n ...200920055097
cigarette smoking during pregnancy: chromosome translocations and phenotypic susceptibility in mothers and newborns.the effects of maternal cigarette smoking during pregnancy on structural chromosome aberrations were evaluated in peripheral lymphocytes from 239 mothers and their 241 newborns to determine whether smoking during pregnancy, genetic susceptibility, and race are associated with chromosome aberrations including translocations. demographic information and cigarette smoking data were obtained via questionnaire. there were 119 caucasian americans, 118 african americans, and 2 asian americans. the aver ...201020060061
chromobacterium violaceum infection in a free-ranging howler monkey in costa rica.chromobacterium violaceum is a gram-negative saprobe bacterium that is a rare opportunistic pathogen in mammals. there are numerous reports in humans including fatalities, but no record exists in free-ranging nonhuman primates. here we report an infection by c. violaceum in a wild adult male howler monkey (alouatta palliata) captured at ballena marine national park, in southwestern costa rica. the individual had severe skin lesions over its extremities; gross findings included multiple skin ulce ...201020090050
structural characterization of the organic solvent-stable cholesterol oxidase from chromobacterium sp. ds-1.cholesterol oxidase is of significant commercial interest as it is widely used as a biosensor for the detection of cholesterol in clinical samples, blood serum and food. increased stability of this enzyme with regards to temperature and different solvent conditions are of great importance to the reliability and versatility of its applications. we here report the crystal structure of the cholesterol oxidase of chromobacterium sp. ds-1 (cholox). in contrast to other previously characterized choles ...201020102741
blocking of pseudomonas aeruginosa and chromobacterium violaceum lectins by diverse mammalian milks.pseudomonas aeruginosa and chromobacterium violaceum morbid and mortal infections are initiated by bacterial adherence to host-cell receptors via their adhesins, including lectins (which also contribute to bacterial biofilm formation). pseudomonas aeruginosa produces a galactophilic lectin, pa-il (leca), and a fucophilic (lewis-specific) lectin, pa-iil (lecb), and c. violaceum produces a fucophilic (h-specific) lectin, cv-iil. the antibiotic resistance of these bacteria prompted the search for g ...201020105519
cross-species induction of antimicrobial compounds, biosurfactants and quorum-sensing inhibitors in tropical marine epibiotic bacteria by pathogens and biofouling microorganisms.enhancement or induction of antimicrobial, biosurfactant, and quorum-sensing inhibition property in marine bacteria due to cross-species and cross-genera interactions was investigated. four marine epibiotic bacteria (bacillus sp. s3, b. pumilus s8, b. licheniformis d1, and serratia marcescens v1) displaying antimicrobial activity against pathogenic or biofouling fungi (candida albicans ca and yarrowia lipolytica yl), and bacteria (pseudomonas aeruginosa pa and bacillus pumilus bp) were chosen fo ...201021086131
volatile-mediated killing of arabidopsis thaliana by bacteria is mainly due to hydrogen cyanide.the volatile-mediated impact of bacteria on plant growth is well documented, and contrasting effects have been reported ranging from 6-fold plant promotion to plant killing. however, very little is known about the identity of the compounds responsible for these effects or the mechanisms involved in plant growth alteration. we hypothesized that hydrogen cyanide (hcn) is a major factor accounting for the observed volatile-mediated toxicity of some strains. using a collection of environmental and c ...201021115704
gram-positive marine bacteria as a potential resource for the discovery of quorum sensing inhibitors.inhibitors of bacterial quorum sensing have been proposed as potentially novel therapeutics for the treatment of certain bacterial diseases. we recently reported a marine halobacillus salinus isolate that secretes secondary metabolites capable of quenching quorum sensing phenotypes in several gram-negative reporter strains. to investigate how widespread the production of such compounds may be in the marine bacterial environment, 332 gram-positive isolates from diverse habitats were tested for th ...201021152942
quorum quenching in cultivable bacteria from dense marine coastal microbial communities.acylhomoserine lactone (ahls)-mediated quorum-sensing (qs) processes seem to be common in the marine environment and among marine pathogenic bacteria, but no data are available on the prevalence of bacteria capable of interfering with qs in the sea, a process that has been generally termed 'quorum quenching' (qq). one hundred and sixty-six strains isolated from different marine dense microbial communities were screened for their ability to interfere with ahl activity. twenty-four strains (14.4%) ...201021155853
new insights into the genetic organization of the fk228 biosynthetic gene cluster in chromobacterium violaceum no. 968.the biosynthetic gene cluster of fk228, an fda-approved anticancer natural product, was identified and sequenced previously. the genetic organization of this gene cluster has now been delineated through systematic gene deletion and transcriptional analysis. as a result, the gene cluster is redefined to contain 12 genes: depa through depj, depm, and a newly identified pathway regulatory gene, depr.201021183645
reconstitution of the fk228 biosynthetic pathway reveals cross talk between modular polyketide synthases and fatty acid synthase.functional cross talk between fatty acid biosynthesis and secondary metabolism has been discovered in several cases in microorganisms; none of them, however, involves a modular biosynthetic enzyme. previously, we reported a hybrid modular nonribosomal peptide synthetase (nrps)-polyketide synthase (pks) pathway for the biosynthesis of fk228 anticancer depsipeptide in chromobacterium violaceum strain 968. this pathway contains two pks modules on the depbc enzymes that lack a functional acyltransfe ...201021183648
regulation of the violacein biosynthetic gene cluster by acylhomoserine lactone-mediated quorum sensing in chromobacterium violaceum atcc 12472.chromobacterium violaceum produces the purple pigment violacein by quorum-sensing regulation. 20-bp of the lux box-like sequence was found upstream of vioa in c. violaceum atcc 12472. cvir received c10-hsl and c6-hsl and activated the transcription of vioa in escherichia coli. however, in strain atcc 12472, c6-hsl inhibited both c10-hsl-mediated violacein production and the transcription of vioa.201020944413
isolation and characterization of new potential probiotic bacteria based on quorum-sensing system.this work was aimed at identifying strains which can degrade quorum-sensing (qs) molecules from fish gut, with properties suitable for use as probiotic in aquaculture.201020955192
enzymatic racemization of amines catalyzed by enantiocomplementary ω-transaminases.a strategy for the biocatalytic racemization of primary α-chiral amines was developed by employing a pair of stereocomplementary plp-dependent ω-transaminases. the interconversion of amine enantiomers proceeded through reversible transamination by a prochiral ketone intermediate, either catalyzed by a pair of stereocomplementary ω-transaminases or by a single enzyme possessing low stereoselectivity. to tune the system, the type and concentration of a nonchiral amino acceptor proved to be crucial ...201021207634
screening of certain medicinal plants from india for their anti-quorum sensing activity.discovery of quorum sensing (qs) system to coordinate virulence and biofilm formation in bacterial pathogens has triggered search for safe, stable and non-toxic anti-qs compounds from natural products. ethanolic extracts of 24 indian medicinal plants were tested by agar well and disc diffusion assay for anti-qs activity using chromobacterium violaceum (cv12472 and cvo26) reporter strains. ahl from c. violaceum cv31532 was isolated and partially purified for its use in cvo26 based bioassay. effec ...201021250604
chromobacterium violaceum and its important metabolites--review.c. violaceum appeared as important bacterium in different applications and mainly these aspects are related to the production of violacein. this review discusses the last reports on biosynthetic pathways, production, genetic aspects, biological activities, pathological effects, antipathogenic screening through quorum sensing, environmental effects and the products of c. violaceum with industrial interest. an important discussion is on biological applications in medicine and as industrial product ...201021253897
inhibition of quorum-sensing signals by essential oils.the role of quorum sensing (qs) is well known in microbial pathogenicity and antibiotic resistance. qs is responsible for motility, swarming, and biofilm production based on the signal molecules, e.g., acylated homoserine lactones (ahls) produced by micro-organisms above certain population density. the inhibition of qs may reduce pathogenicity, antibiotic resistance and biofilm formation in systemic and local infections. the homoserine lactones and other transmitters contribute to antibiotic res ...201019827025
measurement of the intramolecular isotope effect on aliphatic hydroxylation by chromobacterium violaceum phenylalanine hydroxylase.the non-heme iron enzyme phenylalanine hydroxylase from chromobacterium violaceum has previously been shown to catalyze the hydroxylation of benzylic and aliphatic carbons in addition to the normal aromatic hydroxylation reaction. the intrinsic isotope effect for hydroxylation of 3-cyclochexylalanine by the enzyme was determined in order to gain insight into the reactivity of the iron center. with 3-[(2)h(11)-cyclohexyl]alanine as the substrate, the isotope effect on the k(cat) value was 1, cons ...201020355730
rapid degradation of n-3-oxo-acylhomoserine lactones by a bacillus cereus isolate from malaysian rainforest soil.a bacterial strain, km1s, was isolated from a malaysian rainforest soil sample by using a defined enrichment medium that specifically facilitates selection of quorum quenching bacteria. km1s was clustered closely to bacillus cereus by 16s ribosomal dna sequence analysis. it degraded n-3-oxo-hexanoyl homoserine lactone and n-3-oxo-octanoyl homoserine lactone in vitro rapidly at 4.98 and 6.56 microg ahl h(-1) per 10(9) cfu/ml, respectively, as determined by the rapid resolution liquid chromatograp ...201020376561
Displaying items 601 - 700 of 763