Publications

TitleAbstractYear(sorted descending)
Filter
PMID
Filter
divergence and convergence in enzyme evolution: parallel evolution of paraoxonases from quorum-quenching lactonases.we discuss the basic features of divergent versus convergent evolution and of the common scenario of parallel evolution. the example of quorum-quenching lactonases is subsequently described. three different quorum-quenching lactonase families are known, and they belong to three different superfamilies. their key active-site architectures have converged and are strikingly similar. curiously, a promiscuous organophosphate hydrolase activity is observed in all three families. we describe the struct ...201122069329
packaging considerations for biopreservation.summary: the packaging system chosen for biopreservation is critical for many reasons. an ideal biopreservation container system must provide for closure integrity, sample stability and ready access to the preserved material. this means the system needs to be hermetically sealed to ensure integrity of the specimen is maintained throughout processing, storage and distribution; the system must remain stable over long periods of time as many biobanked samples may be stored indefinitely; and functio ...201121566715
comparison of traditional phenotypic identification methods with partial 5' 16s rrna gene sequencing for species-level identification of nonfermenting gram-negative bacilli.correct identification of nonfermenting gram-negative bacilli (nfb) is crucial for patient management. we compared phenotypic identifications of 96 clinical nfb isolates with identifications obtained by 5' 16s rrna gene sequencing. sequencing identified 88 isolates (91.7%) with >99% similarity to a sequence from the assigned species; 61.5% of sequencing results were concordant with phenotypic results, indicating the usability of sequencing to identify nfb.201020164273
analysis of the bacterial communities present in lungs of patients with cystic fibrosis from american and british centers.the aim of this study was to determine whether geographical differences impact the composition of bacterial communities present in the airways of cystic fibrosis (cf) patients attending cf centers in the united states or united kingdom. thirty-eight patients were matched on the basis of clinical parameters into 19 pairs comprised of one u.s. and one united kingdom patient. analysis was performed to determine what, if any, bacterial correlates could be identified. two culture-independent strategi ...201021068277
analysis of the bacterial communities present in lungs of patients with cystic fibrosis from american and british centers.the aim of this study was to determine whether geographical differences impact the composition of bacterial communities present in the airways of cystic fibrosis (cf) patients attending cf centers in the united states or united kingdom. thirty-eight patients were matched on the basis of clinical parameters into 19 pairs comprised of one u.s. and one united kingdom patient. analysis was performed to determine what, if any, bacterial correlates could be identified. two culture-independent strategi ...201021068277
microbiological pattern of arterial catheters in the intensive care unit.intravascular catheter related infection (cri) is one of the most serious nosocomial infections. diagnostic criteria include a positive culture from the catheter tip along with blood, yet in many patients with signs of infection, current culture techniques fail to identify pathogens on catheter segments. we hypothesised that a molecular examination of the bacterial community on short term arterial catheters (acs) would improve our understanding of the variety of organisms that are present in thi ...201020955628
antibiotic resistance characteristics of environmental bacteria from an oxytetracycline production wastewater treatment plant and the receiving river.we characterized the bacterial populations in surface water receiving effluent from an oxytetracycline (otc) production plant. additional sampling sites included the receiving river water 5 km upstream and 20 km downstream from the discharge point. high levels of otc were found in the wastewater (ww), and the antibiotic was still detectable in river water downstream (rwd), with undetectable levels in river water upstream (rwu). a total of 341 bacterial strains were isolated using nonselective me ...201020400569
stereoselective hydrolysis of organophosphate nerve agents by the bacterial phosphotriesterase.organophosphorus compounds include many synthetic, neurotoxic substances that are commonly used as insecticides. the toxicity of these compounds is due to their ability to inhibit the enzyme acetylcholine esterase. some of the most toxic organophosphates have been adapted for use as chemical warfare agents; the most well-known are ga, gb, gd, gf, vx, and vr. all of these compounds contain a chiral phosphorus center, with the s(p) enantiomers being significantly more toxic than the r(p) enantiome ...201020701311
structural determinants for the stereoselective hydrolysis of chiral substrates by phosphotriesterase.wild-type phosphotriesterase (pte) preferentially hydrolyzes the r(p) enantiomers of the nerve agents sarin (gb) and cyclosarin (gf) and their chromophoric analogues. the active site of pte can be subdivided into three binding pockets that have been denoted as the small, large, and leaving group pockets based on high-resolution crystal structures. the sizes and shapes of these pockets dictate the substrate specificity and stereoselectivity for catalysis. mutants of pte that exhibit substantial c ...201020695627
identification of wastewater bacteria involved in the degradation of triclocarban and its non-chlorinated congener.triclocarban (tcc) is an antimicrobial additive of personal care products that is only partially degraded during wastewater treatment. bacteria responsible for its transformation are unknown. we obtained wastewater bacteria capable of using as the sole carbon source tcc or its non-chlorinated analog, carbanilide (ncc). enrichments established using activated sludge amended with tcc and ncc, respectively, were maintained for 1 year through successive transfers. enrichments displayed exponential g ...201020727675
monitoring of diisopropyl fluorophosphate hydrolysis by fluoride-selective polymeric films using absorbance spectroscopy.in this study, a novel system for the detection and quantification of organofluorophosphonates (ofp) has been developed by using an optical sensing polymeric membrane to detect the fluoride ions produced upon ofp hydrolysis. diisopropyl fluorophosphate (dfp), a structural analogue of type g chemical warfare agents such as sarin (gb) and soman (gd), is used as the surrogate target analyte. an optical sensing fluoride ion selective polymeric film was formulated from plasticized pvc containing alum ...201020441875
rnai suppression of arogenate dehydratase1 reveals that phenylalanine is synthesized predominantly via the arogenate pathway in petunia petals.l-phe, a protein building block and precursor of numerous phenolic compounds, is synthesized from prephenate via an arogenate and/or phenylpyruvate route in which arogenate dehydratase (adt) or prephenate dehydratase, respectively, plays a key role. here, we used petunia hybrida flowers, which are rich in phe-derived volatiles, to determine the biosynthetic routes involved in phe formation in planta. of the three identified petunia adts, expression of adt1 was the highest in petunia petals and p ...201020215586
the role of nonbonded interactions in the conformational dynamics of organophosphorous hydrolase adsorbed onto functionalized mesoporous silica surfaces.the enzyme organophosphorous hydrolase (oph) catalyzes the hydrolysis of a wide variety of organophosphorous compounds with high catalytic efficiency and broad substrate specificity. the immobilization of oph in functionalized mesoporous silica (fms) surfaces increases significantly its catalytic specific activity, as compared to the enzyme in solution, with important applications for the detection and decontamination of insecticides and chemical warfare agents. experimental measurements of immo ...201019938866
isothermal dna amplification using the t4 replisome: circular nicking endonuclease-dependent amplification and primase-based whole-genome amplification.in vitro reconstitution of the bacteriophage t4 replication machinery provides a novel system for fast and processive isothermal dna amplification. we have characterized this system in two formats: (i) in circular nicking endonuclease-dependent amplification (cnda), the t4 replisome is supplemented with a nicking endonuclease (nb.bbvci) and a reverse primer to generate a well-defined uniform double-stranded linear product and to achieve up to 1100-fold linear amplification of a plasmid in 1 h. ( ...201020921065
biodegradation of a biocide (cu-n-cyclohexyldiazenium dioxide) component of a wood preservative by a defined soil bacterial community.the wood protection industry has refined their products from chrome-, copper-, and arsenate-based wood preservatives toward solely copper-based preservatives in combination with organic biocides. one of these is cu-hdo, containing the chelation product of copper and n-cyclohexyldiazenium dioxide (hdo). in this study, the fate of isotope-labeled ((13)c) and nonlabeled ((12)c) cu-hdo incorporated in wood sawdust mixed with soil was investigated. hdo concentration was monitored by high-pressure liq ...201020952650
phosphotriesterase variants with high methylphosphonatase activity and strong negative trade-off against phosphotriesters.the most lethal organophosphorus nerve agents (na), like sarin, soman, agent-vx and russian-vx, share a methylphosphonate moiety. pseudomonas diminuta phosphotriesterase (pte) catalyses the hydrolysis of methylphosphonate na analogues with a catalytic efficiency orders of magnitude lower than that towards the pesticide paraoxon. with a view to obtaining pte variants that more readily accept methylphosphonate na, ~75,000 pte variants of the substrate-binding residues gly-60, ile-106, leu-303 and ...201021037279
characterisation of source-separated household waste intended for composting.large-scale composting of source-separated household waste has expanded in recent years in the nordic countries. one problem can be low ph at the start of the process. incoming biowaste at four composting plants was characterised chemically, physically and microbiologically. the ph of food waste ranged from 4.7 to 6.1 and organic acid concentration from 24 to 81 mmol kg(-1). the bacterial diversity in the waste samples was high, with all samples dominated by gammaproteobacteria, particularly pse ...201021075618
characterization of a phosphotriesterase-like lactonase from sulfolobus solfataricus and its immobilization for disruption of quorum sensing.ssopox, a bifunctional enzyme with organophosphate hydrolase and n-acyl homoserine lactonase activities from the hyperthermophilic archaeon sulfolobus solfataricus, was overexpressed and purified from recombinant pseudomonas putida kt2440 with a yield of 9.4 mg of protein per liter of culture. the enzyme has a preference for n-acyl homoserine lactones (ahls) with acyl chain lengths of at least 8 carbon atoms, mainly due to lower k(m) values for these substrates. the highest specificity constant ...201021183649
characterization of a phosphotriesterase-like lactonase from sulfolobus solfataricus and its immobilization for disruption of quorum sensing.ssopox, a bifunctional enzyme with organophosphate hydrolase and n-acyl homoserine lactonase activities from the hyperthermophilic archaeon sulfolobus solfataricus, was overexpressed and purified from recombinant pseudomonas putida kt2440 with a yield of 9.4 mg of protein per liter of culture. the enzyme has a preference for n-acyl homoserine lactones (ahls) with acyl chain lengths of at least 8 carbon atoms, mainly due to lower k(m) values for these substrates. the highest specificity constant ...201021183649
molecular and kinetic characterization of mixed cultures degrading natural and synthetic estrogens.the biodegradation of estradiol (e2), estrone (e1), and ethinylestradiol (ee2) was investigated using mixed bacterial cultures enriched from activated sludge. enrichments were carried out on e2 or ee2 in batch conditions with acetonitrile as additional carbon source. degradation experiments were performed both using hormones as sole carbon source or with an additional source. the hormones were completely degraded by these cultures. estradiol was rapidly converted to e1 within 24 h. thereafter, e ...201019685239
pseudomonads from rabbits and their sensitivity to antibiotics and natural antimicrobials.the sensitivity/resistance of pseudomonas spp. isolated from rabbits gastrointestinal tract and faeces to antibiotics, enterocins and herbal extracts was tested in this study. the counts of pseudomonas-like bacteria were higher in faeces (3.23-6.16 log(10) cfu/ml/g) than in caecum (1.36-4.08 log(10) cfu/ml/g). nineteen isolates (16 faecal, 3 caecal) were oxidase positive. the strains were allotted by phenotypization to pseudomonas spp., brevundimonas diminuta and brevundimonasvesicularis. high p ...201019716146
brevundimonas vancanneytii sp. nov., isolated from blood of a patient with endocarditis.a gram-negative, rod-shaped, non-spore-forming bacterial strain, designated lmg 2337(t), was isolated from the blood of a patient with endocarditis and characterized. the strain was affiliated with the alphaproteobacterial genus brevundimonas, with brevundimonas diminuta lmg 2089(t) (98.3 % 16s rrna gene sequence similarity) and brevundimonas terrae ksl-145(t) (97.5 %) as its closest relatives. this affiliation was supported by chemotaxonomic data: the g+c content was 66.3 mol %, the major polar ...201019880635
cotranslocation of methyl parathion hydrolase to the periplasm and of organophosphorus hydrolase to the cell surface of escherichia coli by the tat pathway and ice nucleation protein display system.a genetically engineered escherichia coli strain coexpressing organophosphorus hydrolase (oph) and methyl parathion hydrolase (mph) was constructed for the first time by cotransforming two compatible plasmids. since these two enzymes have different substrate specificities, the coexpression strain showed a broader substrate range than strains expressing either one of the hydrolases. to reduce the mass transport limitation of organophosphates (ops) across the cell membrane, mph and oph were simult ...201019933341
cotranslocation of methyl parathion hydrolase to the periplasm and of organophosphorus hydrolase to the cell surface of escherichia coli by the tat pathway and ice nucleation protein display system.a genetically engineered escherichia coli strain coexpressing organophosphorus hydrolase (oph) and methyl parathion hydrolase (mph) was constructed for the first time by cotransforming two compatible plasmids. since these two enzymes have different substrate specificities, the coexpression strain showed a broader substrate range than strains expressing either one of the hydrolases. to reduce the mass transport limitation of organophosphates (ops) across the cell membrane, mph and oph were simult ...201019933341
use of hydrogenophaga pseudoflava penetration to quantitatively assess the impact of filtration parameters for 0.2-micrometer-pore-size filters.filters rated as having a 0.2-microm pore size (0.2-microm-rated filters) are used in laboratory and manufacturing settings for diverse applications of bacterial and particle removal from process fluids, analytical test articles, and gasses. using hydrogenophaga pseudoflava, a diminutive bacterium with an unusual geometry (i.e., it is very thin), we evaluated passage through 0.2-microm-rated filters and the impact of filtration process parameters and bacterial challenge density. we show that con ...201019966023
use of hydrogenophaga pseudoflava penetration to quantitatively assess the impact of filtration parameters for 0.2-micrometer-pore-size filters.filters rated as having a 0.2-microm pore size (0.2-microm-rated filters) are used in laboratory and manufacturing settings for diverse applications of bacterial and particle removal from process fluids, analytical test articles, and gasses. using hydrogenophaga pseudoflava, a diminutive bacterium with an unusual geometry (i.e., it is very thin), we evaluated passage through 0.2-microm-rated filters and the impact of filtration process parameters and bacterial challenge density. we show that con ...201019966023
sinorhizobium meliloti phospholipase c required for lipid remodeling during phosphorus limitation.rhizobia are gram-negative soil bacteria able to establish nitrogen-fixing root nodules with their respective legume host plants. besides phosphatidylglycerol, cardiolipin, and phosphatidylethanolamine, rhizobial membranes contain phosphatidylcholine (pc) as a major membrane lipid. under phosphate-limiting conditions of growth, some bacteria replace their membrane phospholipids with lipids lacking phosphorus. in sinorhizobium meliloti, these phosphorus-free lipids are sulfoquinovosyl diacylglyce ...201020018679
sinorhizobium meliloti phospholipase c required for lipid remodeling during phosphorus limitation.rhizobia are gram-negative soil bacteria able to establish nitrogen-fixing root nodules with their respective legume host plants. besides phosphatidylglycerol, cardiolipin, and phosphatidylethanolamine, rhizobial membranes contain phosphatidylcholine (pc) as a major membrane lipid. under phosphate-limiting conditions of growth, some bacteria replace their membrane phospholipids with lipids lacking phosphorus. in sinorhizobium meliloti, these phosphorus-free lipids are sulfoquinovosyl diacylglyce ...201020018679
high-throughput identification of bacteria and yeast by matrix-assisted laser desorption ionization-time of flight mass spectrometry in conventional medical microbiology laboratories.matrix-assisted laser desorption ionization-time of flight mass spectrometry (maldi-tof ms) is suitable for high-throughput and rapid diagnostics at low costs and can be considered an alternative for conventional biochemical and molecular identification systems in a conventional microbiological laboratory. first, we evaluated maldi-tof ms using 327 clinical isolates previously cultured from patient materials and identified by conventional techniques (vitek-ii, api, and biochemical tests). discre ...201020053859
an automated system for rapid non-destructive enumeration of growing microbes.the power and simplicity of visual colony counting have made it the mainstay of microbiological analysis for more than 130 years. a disadvantage of the method is the long time required to generate visible colonies from cells in a sample. new rapid testing technologies generally have failed to maintain one or more of the major advantages of culture-based methods.201020062794
selective enumeration strategies for brevundimonas diminuta from drinking water.brevundimonas diminuta is used as a control organism for validating the efficiency of water filtration systems. since these protocols use nonselective growth media, heterotrophic plate count bacteria (hpcs) indigenous to the water distribution system may interfere with b. diminuta enumeration, thus leading to inaccurate assessment of the filter's microbial reduction capability. this could negatively impact public health as unsafe drinking water may be produced. this study was conducted to evalua ...201020087629
bacterial symbionts of the brown planthopper, nilaparvata lugens (homoptera: delphacidae).the brown planthopper (nilaparvata lugens stål), the most destructive pest of rice, has been identified, including biotypes with high virulence towards previously resistant rice varieties. there have also been many reports of a yeast-like symbiont of n. lugens, but little is known about the bacterial microbes. in this study, we examined the bacterial microbes in n. lugens and identified a total of 18 operational taxonomic units (otus) representing four phyla (proteobacteria, firmicutes, actinoba ...201020097822
lactonases with organophosphatase activity: structural and evolutionary perspectives.serum paraoxonase (pon1) is well recognized for its ability to hydrolyze arylesters, toxic oxon metabolites of organophosphate insecticides and nerve agents. pon1 is a member of gene family including also pon2 and pon3; however, the later two enzymes have very limited arylesterase and practically no organophosphatase activity. we have established that all three pons are lactonases/lactonyzing enzymes with overlapping, but also distinct substrate specificity. dihydrocoumarin (dhc), long chain fat ...201020122908
a localized multimeric anchor attaches the caulobacter holdfast to the cell pole.caulobacter crescentus attachment is mediated by the holdfast, a complex of polysaccharide anchored to the cell by hfaa, hfab and hfad. we show that all three proteins are surface exposed outer membrane (om) proteins. hfaa is similar to fimbrial proteins and assembles into a high molecular weight (hmw) form requiring hfad, but not holdfast polysaccharide. the hfad hmw form is dependent on hfaa but not on holdfast polysaccharide. we show that hfaa and hfad form homomultimers and that they require ...201020233308
the analysis of oral microbial communities of wild-type and toll-like receptor 2-deficient mice using a 454 gs flx titanium pyrosequencer.although mice have long served as an animal model for periodontitis, information on the composition of their indigenous oral microbiota is limited. the aim of the current study was to characterize mouse oral bacterial flora by applying extensive parallel pyrosequencing using the latest model pyrosequencer, a roche/454 genome sequencer flx titanium. in addition, the effect of toll-like receptor (tlr) 2 deficiency on oral microbiota was evaluated.201020370919
recurrent isolation of extremotolerant bacteria from the clean room where phoenix spacecraft components were assembled.the microbial burden of the phoenix spacecraft assembly environment was assessed in a systematic manner via several cultivation-based techniques and a suite of nasa-certified, cultivation-independent biomolecule-based detection assays. extremotolerant bacteria that could potentially survive conditions experienced en route to mars or on the planet's surface were isolated with a series of cultivation-based assays that promoted the growth of a variety of organisms, including spore formers, mesophil ...201020446872
mutation of outer-shell residues modulates metal ion co-ordination strength in a metalloenzyme.the metal ion co-ordination sites of many metalloproteins have been characterized by a variety of spectroscopic techniques and small-molecule model systems, revealing many important insights into the structural determinants of metal ion co-ordination. however, our understanding of this fundamentally and practically important phenomenon remains frustratingly simplistic; in many proteins it is essentially impossible to predict metal ion specificity and the effects of remote 'outer-shell' residues ...201020459397
quantitative real-time pcr and fluorescence in situ hybridization approaches for enumerating brevundimonas diminuta in drinking water.brevundimonas diminuta is a small gram-negative bacterium used for validation of membranes and filters used in the pharmaceutical and drinking water treatment industries. current assays are time consuming, nonselective, and may be subject to interference by competing indigenous microorganisms. the focus of this study is to develop rapid and specific enumeration methodologies for b. diminuta. quantitative real-time polymerase chain reaction (qpcr) and fluorescence in situ hybridization (fish) ass ...201020495940
a bacterial extracellular dna inhibits settling of motile progeny cells within a biofilm.summary in natural systems, bacteria form complex, surface-attached communities known as biofilms. this lifestyle presents numerous advantages compared with unattached or planktonic life, such as exchange of nutrients, protection from environmental stresses and increased tolerance to biocides. despite such benefits, dispersal also plays an important role in escaping deteriorating environments and in successfully colonizing favourable, unoccupied habitat patches. the alpha-proteobacterium cauloba ...201020598083
pharmacokinetics of opda, an organophosphorus hydrolase, in the african green monkey.organophosphorus (op) pesticides are a broad class of acetylcholinesterase inhibitors that are responsible for tremendous morbidity and mortality worldwide, contributing to an estimated 300,000 deaths annually. current pharmacotherapy for acute op poisoning includes the use of atropine, an oxime, and benzodiazepines. however, even with such therapy, the mortality from these agents are as high as 40%. enzymatic hydrolysis of ops is an attractive new potential therapy for acute op poisoning. a num ...201020599794
improving the promiscuous nerve agent hydrolase activity of a thermostable archaeal lactonase.the thermostable phosphotriesterase-like lactonase from sulfolobus solfataricus (ssopox) hydrolyzes lactones and, at a lower rate, neurotoxic organophosphorus compounds. the persistent demand of detoxification tools in the field of agricultural wastes and restoring of conditions after terrorist acts prompted us to exploit ssopox as a "starter" to evolve its ancillary nerve agents hydrolytic capability. a directed evolution strategy yielded, among several variants, the single mutant w263f with k( ...201020667718
rapid detection of pseudomonas aeruginosa from positive blood cultures by quantitative pcr.pseudomonas aeruginosa is responsible for numerous bloodstream infections associated with severe adverse outcomes in case of inappropriate initial antimicrobial therapy. the present study was aimed to develop a novel quantitative pcr (qpcr) assay, using ecfx as the specific target gene, for the rapid and accurate identification of p. aeruginosa from positive blood cultures (bcs).201020684778
obstacles of multiplex real-time pcr for bacterial 16s rdna: primer specifity and dna decontamination of taq polymerase.background: the detection of a broad range of bacteria by pcr is applied for the screening of blood and blood products with special attention to platelet concentrates. for practical use it is desirable that detection systems include gram-positive, gram-negative and non-gram-stainable bacteria. it is quite challenging to achieve high sensitivity along with a clear negative control with pcr reagents, because especially taq polymerase is contaminated with traces of bacterial dna. methods: bacterial ...201020737013
absence of high-risk human papillomavirus (hpv) detection in endocervical adenocarcinoma with gastric morphology and phenotype.a subset of endocervical-type mucinous adenocarcinomas (acs) of the uterine cervix exhibit a gastric phenotype and morphology, as reported in cases of minimal deviation ac in which the presence of human papillomavirus (hpv) has been rarely detected. to investigate the hpv-independent pathway of carcinogenesis in cases of gastric-type ac, we investigated the common high-risk hpv (hr-hpv) status in 52 nonsquamous cell carcinomas, using a pcr-based typing method and immunohistochemistry of p16ink4a ...201020829441
a persistent and diverse airway microbiota present during chronic obstructive pulmonary disease exacerbations.acute exacerbations of chronic obstructive pulmonary disease (copd) are a major source of morbidity and contribute significantly to healthcare costs. although bacterial infections are implicated in nearly 50% of exacerbations, only a handful of pathogens have been consistently identified in copd airways, primarily by culture-based methods, and the bacterial microbiota in acute exacerbations remains largely uncharacterized. the aim of this study was to comprehensively profile airway bacterial com ...201020141328
comparisons of subgingival microbial profiles of refractory periodontitis, severe periodontitis, and periodontal health using the human oral microbe identification microarray.this study compared the subgingival microbiota of subjects with refractory periodontitis (rp) to those in subjects with treatable periodontitis (grs = good responders) or periodontal health (ph) using the human oral microbe identification microarray (homim).200919722792
magnetic circular dichroism study of a dicobalt(ii) complex with mixed 5- and 6-coordination: a spectroscopic model for dicobalt(ii) hydrolases.the magnetic circular dichroism (mcd) study of [co(2)(mu-oh)(mu-ph(4)dba)(tmeda)(2)(otf)], in which ph(4)dba is the dinucleating bis(carboxylate) ligand dibenzofuran-4,6-bis(diphenylacetate) and tmeda is n,n,n',n'-tetramethylethylenediamine, is presented. this complex serves as an excellent spectroscopic model for a number of dicobalt(ii) enzymes and proteins that have both the mu-hydroxo, mu-carboxylato bridging and asymmetric 6- and 5-coordination. the low-temperature mcd spectrum of the model ...200919691327
organophosphate hydrolase in brevundimonas diminuta is targeted to the periplasmic face of the inner membrane by the twin arginine translocation pathway.a twin arginine translocation (tat) motif, involved in transport of folded proteins across the inner membrane, was identified in the signal peptide of the membrane-associated organophosphate hydrolase (oph) of brevundimonas diminuta. expression of the precursor form of oph carrying a c-terminal his tag in an opd-negative background and subsequent immunoblotting with anti-his antibodies showed that only the mature form of oph associated with the membrane and that the precursor form of oph was ent ...200919700527
synthesis and qsar modeling of 2-acetyl-2-ethoxycarbonyl-1-[4(4'-arylazo)-phenyl]-n,n-dimethylaminophenyl aziridines as potential antibacterial agents.the present communication deals with the synthesis of a series of 2-acetyl-2-ethoxycarbonyl-1-[4(4'-arylazo)-phenyl]-n,n-dimethylaminophenyl aziridines. the compounds were synthesized in excellent yields (70-80%) and the structures were established on the basis of consistent ir, (1)h nmr and elemental analysis data. the purity has been ascertained by chromatographic resolution using acetic acid--toluene (6:4v/v) as binary eluent. all the compounds have been tested for their antimicrobial activit ...200918396359
production of l-malic acid with fixation of hco3(-) by malic enzyme-catalyzed reaction based on regeneration of coenzyme on electrode modified by layer-by-layer self-assembly method.malic enzyme prepared and purified from brevundimonas diminuta ifo13182 catalyzed the decarboxylation reaction of malate to pyruvate and co2 using nad+ as the coenzyme, and the reverse reaction was used in the present study for l-malic acid production with fixation of hco3(-) as a model compound for carbon source. the l-malic acid production was based on electrochemical regeneration of nadh on a carbon plate electrode modified by layer-by-layer adsorption of polymer-bound mediator (alginic acid ...200919147103
functional annotation and three-dimensional structure of dr0930 from deinococcus radiodurans, a close relative of phosphotriesterase in the amidohydrolase superfamily.dr0930, a member of the amidohydrolase superfamily in deinococcus radiodurans, was cloned, expressed, and purified to homogeneity. the enzyme crystallized in the space group p3121, and the structure was determined to a resolution of 2.1 a. the protein folds as a (beta/alpha)7beta-barrel, and a binuclear metal center is found at the c-terminal end of the beta-barrel. the purified protein contains a mixture of zinc and iron and is intensely purple at high concentrations. the purple color was deter ...200919159332
structural determinants of the high thermal stability of ssopox from the hyperthermophilic archaeon sulfolobus solfataricus.organophosphates (ops) constitute the largest class of insecticides used worldwide and certain of them are potent nerve agents. consequently, enzymes degrading ops are of paramount interest, as they could be used as bioscavengers and biodecontaminants. looking for a stable ops catalyst, able to support industrial process constraints, a hyperthermophilic phosphotriesterase (pte) (ssopox) was isolated from the archaeon sulfolobus solfataricus and was found to be highly thermostable. the solved 3d ...200919247785
functional identification of incorrectly annotated prolidases from the amidohydrolase superfamily of enzymes.the substrate profiles for two proteins from caulobacter crescentus cb15 (cc2672 and cc3125) and one protein (sgx9359b) derived from a dna sequence ( gi|44368820 ) isolated from the sargasso sea were determined using combinatorial libraries of dipeptides and n-acyl derivatives of amino acids. these proteins are members of the amidohydrolase superfamily and are currently misannotated in ncbi as catalyzing the hydrolysis of l-xaa-l-pro dipeptides. cc2672 was shown to catalyze the hydrolysis of l-x ...200919281183
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
evolution in the amidohydrolase superfamily: substrate-assisted gain of function in the e183k mutant of a phosphotriesterase-like metal-carboxylesterase.the recent specialization for utilization of pesticides reported for pseudomonas diminuta phosphotriesterase (ppte) strongly suggests that this activity evolved from an enzyme endowed with promiscuous phosphotriesterase activity. such a putative "generalist" enzyme was recently proposed to be a member of the new phoshotriesterase-like lactonase family (pll). the promiscuous carboxylesterase and phosphodiesterase activities detected in ppte and plls in turn paved the way for the prediction of the ...200919438255
modelling substrate specificity and enantioselectivity for lipases and esterases by substrate-imprinted docking.previously, ways to adapt docking programs that were developed for modelling inhibitor-receptor interaction have been explored. two main issues were discussed. first, when trying to model catalysis a reaction intermediate of the substrate is expected to provide more valid information than the ground state of the substrate. second, the incorporation of protein flexibility is essential for reliable predictions.200919493341
structure-based rational design of a phosphotriesterase.in silico substrate docking of both stereoisomers of the pesticide chlorfenvinphos (cvp) in the phosphotriesterase from agrobacterium radiobacter identified two residues (f131 and w132) that prevent productive substrate binding and cause stereospecificity. a variant (w131h/f132a) was designed that exhibited ca. 480-fold and 8-fold increases in the rate of z-cvp and e-cvp hydrolysis, respectively, eliminating stereospecificity.200919502439
update on biochemical properties of recombinant pseudomonas diminuta phosphotriesterase.phosphotriesterase from pseudomonas diminuta (pte; ec 3.1.8.1) hydrolyzes organophosphate insecticides and chemical warfare agents. the two zinc cations in the active center can be substituted. co(2+)-containing pte is the most efficient but least stable isoform. gel filtration showed that pte is monomeric at the submicromolar concentrations used in kinetic assays. the analysis of the recombinant enzyme by x-ray fluorescence spectrometry and cct-icp-ms, confirms that recombinant zn-pte contains ...200919548794
structure-based and random mutagenesis approaches increase the organophosphate-degrading activity of a phosphotriesterase homologue from deinococcus radiodurans.an enzyme from the amidohydrolase family from deinococcus radiodurans (dr-oph) with homology to phosphotriesterase has been shown to exhibit activity against both organophosphate (op) and lactone compounds. we have characterized the physical properties of dr-oph and have found it to be a highly thermostable enzyme, remaining active after 3 h of incubation at 60 degrees c and withstanding incubation at temperatures up to 70 degrees c. in addition, it can withstand concentrations of at least 200 m ...200919631223
nitrate removal using brevundimonas diminuta mtcc 8486 from ground water.brevundimonas diminuta mtcc 8486, isolated from marine soil of coastal area of trivandrum, kerala, was used for biological removal of nitrate from ground water collected from kar village of pali district, rajasthan. the organism was found to be resistance for nitrate up to 10,000 mg l(-1). the optimum growth conditions for biological removal of nitrate were established in batch culture. the effect of carbon sources on nitrate removal was investigated using mineral salt medium (msm) containing 50 ...200919633395
brevundimonas naejangsanensis sp. nov., a proteolytic bacterium isolated from soil, and reclassification of mycoplana bullata into the genus brevundimonas as brevundimonas bullata comb. nov.a gram-negative, motile and rod-shaped bacterial strain, bio-tas2-2(t), of the class alphaproteobacteria, was isolated from a soil in korea and studied using a polyphasic taxonomic approach. strain bio-tas2-2(t) grew optimally at ph 7.5-8.5 and 30 degrees c and in the presence of 0-1.0 % (w/v) nacl. a neighbour-joining phylogenetic tree based on 16s rrna gene sequences showed that strain bio-tas2-2(t) fell within the clade comprising species of the genus brevundimonas, forming a coherent cluster ...200919643873
conformational sampling, catalysis, and evolution of the bacterial phosphotriesterase.to efficiently catalyze a chemical reaction, enzymes are required to maintain fast rates for formation of the michaelis complex, the chemical reaction and product release. these distinct demands could be satisfied via fluctuation between different conformational substates (css) with unique configurations and catalytic properties. however, there is debate as to how these rapid conformational changes, or dynamics, exactly affect catalysis. as a model system, we have studied bacterial phosphotriest ...200919966226
isolation and identification of profenofos degrading bacteria.an enrichment culture technique was used to isolate bacterial strains responsible for the biodegradation of profenofos in a soil from hubei province of central china. two pure bacterial cultures, named w and y, were isolated and subsequently characterized by sequencing of 16s rrna genes and biochemical tests. isolate w showed 96% similarity to the 16s rrna gene of a pseudomonas putida unlike y which showed 99% similarity to the 16s rrna gene of burkholderia gladioli. both strains grew well at ph ...200924031438
molecular dynamics simulations of the detoxification of paraoxon catalyzed by phosphotriesterase.combined qm(pm3)/mm molecular dynamics simulations together with qm(dft)/mm optimizations for key configurations have been performed to elucidate the enzymatic catalysis mechanism on the detoxification of paraoxon by phosphotriesterase (pte). in the simulations, the pm3 parameters for the phosphorous atom were reoptimized. the equilibrated configuration of the enzyme/substrate complex showed that paraoxon can strongly bind to the more solvent-exposed metal ion zn(beta), but the free energy profi ...200919353598
probing mechanisms for enzymatic activity enhancement of organophosphorus hydrolase in functionalized mesoporous silica.we have previously reported that organophosphorus hydrolase (oph) can be spontaneously entrapped in functionalized mesoporous silica (fms) with hooc- as the functional groups and the entrapped oph in hooc-fms showed enhanced enzyme specific activity. this work is to study the mechanisms that why oph entrapped in fms displayed the enhanced activity in views of oph-fms interactions using spectroscopic methods. the circular dichroism (cd) spectra show that, comparing to the secondary structure of o ...200919874798
hotspot wizard: a web server for identification of hot spots in protein engineering.hotspot wizard is a web server for automatic identification of 'hot spots' for engineering of substrate specificity, activity or enantioselectivity of enzymes and for annotation of protein structures. the web server implements the protein engineering protocol, which targets evolutionarily variable amino acid positions located in the active site or lining the access tunnels. the 'hot spots' for mutagenesis are selected through the integration of structural, functional and evolutionary information ...200919465397
filter preconditioning enables representative scaled-down modelling of filter capacity and viral clearance by mitigating the impact of virus spike impurities.endogenous and adventitious virus removal by size-exclusion membrane filtration is a critical dedicated step in an overall viral clearance strategy employed by biologics manufacturers as required by industry regulators. however, the addition of impurities from virus spike preparations used in validation studies can significantly reduce filter capacity, resulting in an oversized and suboptimal virus filtration step. the hydraulic filter performance and virus retention observed in conventional sca ...200918844606
avian incubation inhibits growth and diversification of bacterial assemblages on eggs.microbial infection is a critical source of mortality for early life stages of oviparous vertebrates, but parental defenses against infection are less well known. avian incubation has been hypothesized to reduce the risk of trans-shell infection by limiting microbial growth of pathogenic bacteria on eggshells, while enhancing growth of commensal or beneficial bacteria that inhibit or competitively exclude pathogens. we tested this hypothesis by comparing bacterial assemblages on naturally incuba ...200919225566
transient expression of organophosphorus hydrolase to enhance the degrading activity of tomato fruit on coumaphos.we constructed an expression cassette of the organophosphorus pesticide degrading (opd) gene under the control of the e8 promoter. then opd was transformed into tomato fruit using an agroinfiltration transient expression system. beta-glucuronidase (gus) staining, reverse transcription-polymerase chain reaction (rt-pcr), wavelength scanning, and fluorescent reaction were performed to examine the expression of the opd gene and the hydrolysis activity on coumaphos of organophosphorus hydrolase (oph ...200919235273
from solvolysis to self-assembly.my sojourn from classical physical-organic chemistry and solvolysis to self-assembly and supramolecular chemistry, over the last forty years, is described. my contributions to unsaturated reactive intermediates, namely vinyl cations and unsaturated carbenes, along with my decade-long involvement with polyvalent iodine chemistry, especially alkynyliodonium salts, as well as my more recent research with metal-ligand, coordination driven, and directed self-assembly of finite supramolecular ensemble ...200919111062
validation of vitek 2 nonfermenting gram-negative cards and vitek 2 version 4.02 software for identification and antimicrobial susceptibility testing of nonfermenting gram-negative rods from patients with cystic fibrosis.accurate identification and antimicrobial susceptibility testing (ast) of nonfermenters from cystic fibrosis patients are essential for appropriate antimicrobial treatment. this study examined the ability of the newly designed vitek 2 nonfermenting gram-negative card (ngnc) (new gram-negative identification card; biomérieux, marcy-l'etoile, france) to identify nonfermenting gram-negative rods from cystic fibrosis patients in comparison to reference methods and the accuracy of the new vitek 2 ver ...200919710272
catalytic bioscavengers against toxic esters, an alternative approach for prophylaxis and treatments of poisonings.bioscavengers are biopharmaceuticals that specifically react with toxicants. thus, enzymes reacting with poisonous esters can be used as bioscavengers for neutralization of toxic molecules before they reach physiological targets. parenteral administration of bioscavengers is, therefore, intended for prophylaxis or pre-treatments, emergency and post-exposure treatments of intoxications. these enzymes can also be used for application on skin, mucosa and wounds as active components of topical skin ...200922649587
high interlaboratory reproducibility of matrix-assisted laser desorption ionization-time of flight mass spectrometry-based species identification of nonfermenting bacteria.matrix-assisted laser desorption ionization-time of flight mass spectrometry has emerged as a rapid, cost-effective alternative for bacterial species identification. identifying 60 blind-coded nonfermenting bacteria samples, this international study (using eight laboratories) achieved 98.75% interlaboratory reproducibility. only 6 of the 480 samples were misidentified due to interchanges (4 samples) or contamination (1 sample) or not identified because of insufficient signal intensity (1 sample) ...200919776231
analysis of bacterial dna in synovial tissue of tunisian patients with reactive and undifferentiated arthritis by broad-range pcr, cloning and sequencing.bacteria and/or their antigens have been implicated in the pathogenesis of reactive arthritis (rea). several studies have reported the presence of bacterial antigens and nucleic acids of bacteria other than those specified by diagnostic criteria for rea in joint specimens from patients with rea and various arthritides. the present study was conducted to detect any bacterial dna and identify bacterial species that are present in the synovial tissue of tunisian patients with reactive arthritis and ...200818412942
reverse reaction of malic enzyme for hco3- fixation into pyruvic acid to synthesize l-malic acid with enzymatic coenzyme regeneration.malic enzyme [l-malate: nad(p)(+) oxidoreductase (ec 1.1.1.39)] catalyzes the oxidative decarboxylation of l-malic acid to produce pyruvic acid using the oxidized form of nad(p) (nad(p)(+)). we used a reverse reaction of the malic enzyme of pseudomonas diminuta ifo 13182 for hco(3)(-) fixation into pyruvic acid to produce l-malic acid with coenzyme (nadh) generation. glucose-6-phosphate dehydrogenase (ec1.1.1.49) of leuconostoc mesenteroides was suitable for coenzyme regeneration. optimum condit ...200818460807
structure of diethyl phosphate bound to the binuclear metal center of phosphotriesterase.the bacterial phosphotriesterase (pte) from pseudomonas diminuta catalyzes the hydrolysis of organophosphate esters at rates close to the diffusion limit. x-ray diffraction studies have shown that a binuclear metal center is positioned in the active site of pte and that this complex is responsible for the activation of the nucleophilic water from solvent. in this paper, the three-dimensional structure of pte was determined in the presence of the hydrolysis product, diethyl phosphate (dep), and a ...200818702530
chemotaxonomy of bacteria by comprehensive gc and gc-ms in electron impact and chemical ionisation mode.the analysis of the cellular lipidic fraction of bacteria is described. after hydrolysis and methylation, the fatty acid methyl esters (fames) are determined by 1-d gc using the sherlock midi bacteria identification system, by comprehensive gc (gc x gc) and by gc-ms in electron impact (ei) and positive chemical ionisation (pci) mode. with gc x gc, the enhanced selectivity and group type separation provides a more complete elucidation of the fatty acids in microorganisms. gc-ei-ms and gc-pci-ms w ...200818792008
influence of size, shape, and flexibility on bacterial passage through micropore membrane filters.sterilization of fluids by means of microfiltration is commonly applied in research laboratories as well as in pharmaceutical and industrial processes. sterile micropore filters are subject to microbiological validation, where brevundimonas diminuta is used as a standard test organism. however, several recent reports on the ubiquitous presence of filterable bacteria in aquatic environments have cast doubt on the accuracy and validity of the standard filter-testing method. six different bacterial ...200818800559
substrate-promoted formation of a catalytically competent binuclear center and regulation of reactivity in a glycerophosphodiesterase from enterobacter aerogenes.the glycerophosphodiesterase (gpdq) from enterobacter aerogenes is a promiscuous binuclear metallohydrolase that catalyzes the hydrolysis of mono-, di-, and triester substrates, including some organophosphate pesticides and products of the degradation of nerve agents. gpdq has attracted recent attention as a promising enzymatic bioremediator. here, we have investigated the catalytic mechanism of this versatile enzyme using a range of techniques. an improved crystal structure (1.9 a resolution) i ...200818831553
[degradation of hydrocarbons and their derivatives by a microbial association based on canadian pondweed].the degrading action of an aquatic plant-microbial association on the base of canadian pondweed (elodea canadensis) and its components (sterilized plant and two periphytonic strains, pseudomonas fluorescens e1-2.1 and brevundimonas diminuta e1-3.1) on crude oil, the water-soluble crude oil fraction, and individual test compounds (phenol, toluene, benzene, decalin, and naphthalene) was studied. it was found that the native association had a wider range and higher degree of degrading activity than ...200818924409
first isolation of two colistin-resistant emerging pathogens, brevundimonas diminuta and ochrobactrum anthropi, in a woman with cystic fibrosis: a case report.cystic fibrosis afflicted lungs support the growth of many bacteria rarely implicated in other cases of human infections.200819061488
adhesion and viability of waterborne pathogens on p-dadmac coatings.the attachment of waterborne pathogens onto surfaces can be increased by coating the surfaces with positive charge-enhancing polymers. in this paper, the increased efficacy of polydiallyldimethylammonium chloride (p-dadmac) coatings on glass was evaluated in a parallel plate flow chamber with the use of waterborne pathogens (raoultella terrigena, escherichia coli, and brevundimonas diminuta). p-dadmac coatings strongly compensated the highly negative charges on the glass surface and even yielded ...200817570712
bismuth dimercaptopropanol (bisbal) inhibits the expression of extracellular polysaccharides and proteins by brevundimonas diminuta: implications for membrane microfiltration.a 2:1 molar ratio preparation of bismuth with a lipophilic dithiol (3-dimercapto-1-propanol, bal) significantly reduced extracellular polymeric substances (eps) expression by brevundimonas diminuta in suspended cultures at levels just below the minimum inhibitory concentration (mic). total polysaccharides and proteins secreted by b. diminuta decreased by approximately 95% over a 5-day period when exposed to the bismuth-bal chelate (bisbal) at near mic (12 microm). fourier-transform infrared spec ...200817705249
purification and immobilization of recombinant variants of brevundimonas diminuta glutaryl-7-aminocephalosporanic acid acylase expressed in escherichia coli cells.modified chitin-binding domain (chbd) from bacillus circulans chitinase a1 with w42f mutation in chitin-binding site was genetically fused to different positions within alpha-subunit of glutaryl-7-aminocephalosporanic acid acylase (gla) gene. hybrid proteins were efficiently expressed in e. coli cells as soluble, enzymatically active and correctly processed holoenzymes. chbd-gla fusions were easily affinity purified on chitin column by changing the salt concentration of binding and elution buffe ...200817963935
effect of shadowing on survival of bacteria under conditions simulating the martian atmosphere and uv radiation.spacecraft-associated spores and four non-spore-forming bacterial isolates were prepared in atacama desert soil suspensions and tested both in solution and in a desiccated state to elucidate the shadowing effect of soil particulates on bacterial survival under simulated martian atmospheric and uv irradiation conditions. all non-spore-forming cells that were prepared in nutrient-depleted, 0.2-microm-filtered desert soil (dse) microcosms and desiccated for 75 days on aluminum died, whereas cells p ...200818083857
effect of shadowing on survival of bacteria under conditions simulating the martian atmosphere and uv radiation.spacecraft-associated spores and four non-spore-forming bacterial isolates were prepared in atacama desert soil suspensions and tested both in solution and in a desiccated state to elucidate the shadowing effect of soil particulates on bacterial survival under simulated martian atmospheric and uv irradiation conditions. all non-spore-forming cells that were prepared in nutrient-depleted, 0.2-microm-filtered desert soil (dse) microcosms and desiccated for 75 days on aluminum died, whereas cells p ...200818083857
genotyping of human papillomaviruses by a novel one-step typing method with multiplex pcr and clinical applications.we describe here a rapid, high-throughput genotyping procedure that allows the simultaneous detection of 16 high- and low-risk genital human papillomavirus (hpv) types by multiplex pcr in a single reaction tube. multiplex pcr is based on the amplification of hpv dna by sets of hpv genotype-specific primers, and the genotypes of hpv are visually identified by the sizes of amplicons after they are separated by capillary electrophoresis. the procedure does not include a hybridization step with hpv- ...200818234872
survey of bacterial diversity in chronic wounds using pyrosequencing, dgge, and full ribosome shotgun sequencing.chronic wound pathogenic biofilms are host-pathogen environments that colonize and exist as a cohabitation of many bacterial species. these bacterial populations cooperate to promote their own survival and the chronic nature of the infection. few studies have performed extensive surveys of the bacterial populations that occur within different types of chronic wound biofilms. the use of 3 separate16s-based molecular amplifications followed by pyrosequencing, shotgun sanger sequencing, and denatur ...200818325110
the airborne metagenome in an indoor urban environment.the indoor atmosphere is an ecological unit that impacts on public health. to investigate the composition of organisms in this space, we applied culture-independent approaches to microbes harvested from the air of two densely populated urban buildings, from which we analyzed 80 megabases genomic dna sequence and 6000 16s rdna clones. the air microbiota is primarily bacteria, including potential opportunistic pathogens commonly isolated from human-inhabited environments such as hospitals, but non ...200818382653
cohesion group approach for evolutionary analysis of tyra, a protein family with wide-ranging substrate specificities.many enzymes and other proteins are difficult subjects for bioinformatic analysis because they exhibit variant catalytic, structural, regulatory, and fusion mode features within a protein family whose sequences are not highly conserved. however, such features reflect dynamic and interesting scenarios of evolutionary importance. the value of experimental data obtained from individual organisms is instantly magnified to the extent that given features of the experimental organism can be projected u ...200818322033
chromate-tolerant bacteria for enhanced metal uptake by eichhornia crassipes (mart.).a total of 85 chromate-resistant bacteria were isolated from the rhizosphere of water hyacinth grown in mariout lake, egypt, as well as the sediment and water of this habitat. only 4 (11%), 2 (8%), and 2 (8%) of isolates from each of the environments, respectively, were able to tolerate 200 mg cr (vi) l(-1). when these eight isolates were tested for their ability to tolerate other metals or to reduce chromate, they were shown to also be resistant to zn, mn, and pb, and to display different degre ...200718246718
filters reduce the risk of bacterial transmission from contaminated heated humidifiers used with cpap for obstructive sleep apnea.the treatment of choice for obstructive sleep apnea (osa) is nasal continuous positive airway pressure (ncpap) during sleep, but dryness of the upper airway compromises compliance. heated humidifiers may mitigate such noncompliance; however, recent observations suggest that their use, particularly if not cleaned, increases the risk of respiratory infections. humidifier water may be contaminated, but the long-held view that passive humidifiers cannot aerosolize water may obscure the perception of ...200718198803
optimization of ascorbic acid-2-phosphate production from ascorbic acid using resting cell of brevundimonas diminuta.with the aim to produce ascorbic acid-2-phosphate (asa-2-p) from l-ascorbic acid (asa, vitamin c), nine bacteria conferring the ability to transform asa to asa-2-p were isolated from soil samples alongside known strains from culture collections. most isolates were classified to the genus brevundimonas by 16s phylogenetic analysis. among them, brevundimonas diminuta kacc 10306 was selected as the experimental strain because of its the highest productivity of asa-2-p. the optimum set of conditions ...200718051298
[cloning and expression of variants of the glutaryl-7-aminocephalosporic acid acylase of the bacterium brevundimonas diminuta in escherichia coli cells].the gene coding for glutaryl-7-aminocephalosporic acid acylase (gl7aca acylase) of the bacterium brevundimonas diminuta (brdgl7aca), a commercial enzyme widely used in modem biocatalytic technologies for manufacture of b-lactam antibiotics, was cloned. efficient expression systems for producing a "native" recombinant brdgl7aca and its analogs modified by attaching affinity groups--the chitin-binding domain of chitinases a1 and hexahistidine sequence--were designed. it was demonstrated that both ...200717929575
evaluation of pyrrolidonyl arylamidase for the identification of nonfermenting gram-negative rods.to evaluate the activity of pyrrolidonyl arylamidase (pyr) for the differentiation and identification of nonfermenting gram negative rods (nfgnr), 293 isolates were tested. a 24 h culture of each test organism was prepared. from this a 108-109 cfu/ml suspension was added to 0.25 ml of sterile physiologic solution. a pyr disk was then added and the test was incubated for 30 minutes at 35-37 degrees c, at environmental atmosphere. reading was done by adding 1 drop of cinnamaldehyde reagent. strain ...200716822636
cloning of a novel aldo-keto reductase gene from klebsiella sp. strain f51-1-2 and its functional expression in escherichia coli.a soil bacterium capable of metabolizing organophosphorus compounds by reducing the p s group in the molecules was taxonomically identified as klebsiella sp. strain f51-1-2. the gene involved in the reduction of organophosphorus compounds was cloned from this strain by the shotgun technique, and the deduced protein (named akr5f1) showed homology to members of the aldo-keto reductase (akr) superfamily. the intact coding region for akr5f1 was subcloned into vector pet28a and overexpressed in esche ...200717575004
crystallization and preliminary x-ray diffraction analysis of the hyperthermophilic sulfolobus solfataricus phosphotriesterase.organophosphates constitute the largest class of insecticides used worldwide and some of them are potent nerve agents. consequently, organophosphate-degrading enzymes are of paramount interest as they could be used as bioscavengers and biodecontaminants. phosphotriesterases (ptes) are capable of hydrolyzing these toxic compounds with high efficiency. a distant and hyperthermophilic representative of the pte family was cloned from the archeon sulfolobus solfataricus mt4, overexpressed in escheric ...200717620708
reusability of entrapped cells of pseudomonas diminuta for production of 7-aminocephalosporanic acid.entrapped cells of p. diminuta were used for the production of 7-aminocephalosporanic acid (7-aca), a key intermediate required for the production of most of the clinically used cephalosporin derivatives, i.e., semisynthetic cephalosporins. the repeated batch production of 7-aca with entrapped cells of p. diminuta in different carriers were carried out for six cycles at optimal conditions. it was found that 33% , 38%, and 47% of activity was lost with chitosan, gelatin, and agar, respectively as ...200717625270
an extremely oligotrophic bacterium, rhodococcus erythropolis n9t-4, isolated from crude oil.rhodococcus erythropolis n9t-4, which was isolated from crude oil, showed extremely oligotrophic growth and formed its colonies on a minimal salt medium solidified using agar or silica gel without any additional carbon source. n9t-4 did not grow under co(2)-limiting conditions but could grow on a medium containing nahco(3) under the same conditions, suggesting that the oligotrophic growth of n9t-4 depends on co(2). proteomic analysis of n9t-4 revealed that two proteins, with molecular masses of ...200717675378
microbial production of 7-amino-cephalosporanic acid and new generation cephalosporins (cephalothin) by different processing strategies.the development of beta-lactam antibiotics has been a continuous battle of the design of new compounds to withstand inactivation by the ever-increasing diversity of beta-lactamases. semisynthetic cephalosporins like cephalothin were synthesized from 7-amino-cephalosporanic acid (7-aca), and thiophene-2-acetic acid using cephalosporin-c acylase enzyme was studied. the production of cephalosporin-c acylase by pseudomonas diminuta was used and the growth kinetics studied. the optimum condition of e ...200717701482
Refresh
firstprev
123456
nextlast
Displaying items 201 - 300 of 520