| inability of the polyphasic approach to systematics to determine the relatedness of the genera xenorhabdus and photorhabdus. | comparative analysis of the genes coding for 16s rrna of the type strains of xenorhabdus and photorhabdus species indicates the close phylogenetic relationship of these two genera. however, distance matrix analyses do not unambiguously separate the symbionts of entomopathogenic nematodes according to their assignment into different genera. when various 16s rrna gene sequences from a selection of members of the gamma subclass of proteobacteria and outgroup taxa were used, the intrageneric relatio ... | 1995 | 7537072 |
| susceptibility of suspended and surface-attached salmonella enteritidis to biocides and elevated temperatures. | the differential resistance of substratum-attached, detached, and planktonic cells of salmonella enteritidis phage type 4 was studied by using several inimical processes and in vivo bioluminescence as a nondestructive, real-time reporter of metabolic activity. bioluminescence in this strain was mediated by a construction containing the entire lux operon from photorhabdus luminescens. an excellent correlation between bioluminescence and classical plate count data was obtained when we compared att ... | 1995 | 7646010 |
| identification of the genes encoding nad(p)h-flavin oxidoreductases that are similar in sequence to escherichia coli fre in four species of luminous bacteria: photorhabdus luminescens, vibrio fischeri, vibrio harveyi, and vibrio orientalis. | genes encoding nad(p)h-flavin oxidoreductases (flavin reductases) similar in both size and sequence to fre, the most abundant flavin reductase in escherichia coli, were identified in four species of luminous bacteria, photorhabdus luminescens (atcc 29999), vibrio fischeri (atcc 7744), vibrio harveyi (atcc 33843), and vibrio orientalis (atcc 33934). nucleotide sequence analysis showed fre-like flavin reductases in p. luminescens and v. fischeri to consist of 233 and 236 amino acids, respectively. ... | 1994 | 8206831 |
| the gene coding for polynucleotide phosphorylase in photorhabdus sp. strain k122 is induced at low temperatures. | photorhabdus sp. strain k122 was found to produce higher levels of the protein cap87k when cultured at 9 degrees c than when cultured at 28 degrees c. nh2-terminal sequencing of this protein revealed homology with the nh2 terminus of escherichia coli polynucleotide phosphorylase. a 4.5-kb dna fragment from strain k122 was cloned and sequenced and found to have 75% identity to the e. coli rpso-pnp operon coding for ribosomal protein s15 and polynucleotide phosphorylase, respectively. predicted pr ... | 1994 | 8206856 |
| identification of two pigments and a hydroxystilbene antibiotic from photorhabdus luminescens. | two yellow pigments were isolated for the first time from the entomopathogenic bacterium photorhabdus luminescens in liquid culture and were identified as the anthraquinone derivatives 3,8-dimethoxy-1-hydroxy-9,10-anthraquinone (minor) and 1,3-dimethoxy-8-hydroxy-9,10-anthraquinone (major). a known antibiotic, 3,5-dihydroxy-4-isopropylstilbene, was also detected and for the first time showed strong fungicidal activity against several fungi of medical and agricultural importance. | 1995 | 8534100 |
| ecology of anti-microbials produced by bacterial associates of steinernema carpocapsae and heterorhabditis bacteriophora. | based on the ability of bacterial associates of entomopathogenic nematodes to produce antibiotic compounds on artificial media, it has been commonly accepted that xenorhabdus sp. and photorhabdus sp. inhibit a wide range of invading microorganisms in insects infected with steinernema spp. or heterorhabditis spp. therefore, the question of whether antibiotic compounds produced by the primary form of bacterial symbionts associated mutualistically with s. carpocapsae and h. bacteriophora explain wh ... | 1996 | 8684829 |
| molecular biology of the symbiotic-pathogenic bacteria xenorhabdus spp. and photorhabdus spp. | | 1996 | 8852894 |
| chitinase activity of xenorhabdus and photorhabdus species, bacterial associates of entomopathogenic nematodes. | xenorhabdus nematophilus (three strains), xenorhabdus bovienii (one strain), and photorhabdus luminescens (one strain) showed both exo- and endochitinase activity using p-nitrophenyl-n-acetyl-beta-d-glucosaminide and p-nitrophenyl-beta-d-n,n',n'-triacetylchitotriose, respectively, as substrates. one to three bands were detected on page gel with glycol chitin after electrophoresis. variation in exo- and endochitinase activity among different species and strains was detected with the strongest act ... | 1996 | 8858906 |
| effect of cucurbitacin d on in vitro growth of xenorhabdus and photorhabdus spp., symbiotic bacteria of entomopathogenic nematodes. | in vitro assays were conducted to determine the effect of cucurbitacin d, an oxygenated tetracyclic triterpenoid found in cucurbits, on the growth of xenorhabdus isolated from steinernema carpocapsae (all, mexican, agriotos strains), steinernema riobravis, steinernema glaseri (nc strain, strain 27), and photorhabdus from heterorhabditis bacteriophora (nc, lewiston strains), and heterorhabditis sp. (fl2122 strain). cucurbitacin d inhibited the growth of four isolates, had no effect on the growth ... | 1996 | 8858910 |
| phenotypic and dna relatedness between nematode symbionts and clinical strains of the genus photorhabdus (enterobacteriaceae). | bacterial strains isolated from wide ranges of nematode hosts and geographic sources and strains isolated from human clinical specimens were used to assess the taxonomic structure of the genus photorhabdus. the following two methods were used: dna relatedness and phenotypic characterization. analysis of the dna relatedness data revealed that all of the strains studied were congeneric and that the genus photorhabdus is, on the basis of dna relatedness data, more homogeneous than the other genus o ... | 1996 | 8863433 |
| phylogenetic relationships of entomopathogenic nematophilic bacteria: xenorhabdus spp. and photorhabdus sp. | phylogenetic relationships of xenorhabdus spp. and photorhabdus sp. were investigated on the basis of 16s rrna gene sequences. xenorhabdus spp. and photorhabdus sp. were grouped together with proteus vulgaris and arsenophonus nasoniae. this group was distant from other members of the family enterobacteriaceae. xenorhabdus japonicus, previously proposed as a new species, was nearly located to xenorhabdus nematophilus. signature nucleotides of x. japonicus were identified that distinguish it other ... | 1996 | 8914266 |
| fast and accurate identification of xenorhabdus and photorhabdus species by restriction analysis of pcr-amplified 16s rrna genes. | thirteen bacterial strains of xenorhabdus and 14 strains of photorhabdus originating from a wide range of geographical and nematode host sources were typed by analyzing 16s rrna gene (rdna) restriction patterns obtained after digestion of pcr-amplified 16s rdnas. eight tetrameric restriction endonucleases were examined. a total of 17 genotypes were identified, forming two heterogeneous main clusters after analysis by the unweighted pair-group method using arithmetic averages: group i included al ... | 1997 | 9023937 |
| phylogenetic evidence for the taxonomic heterogeneity of photorhabdus luminescens. | the sequences of the 16s rrna gene of 40 strains of bacterial symbionts isolated from the nematodes heterorhabditis spp. and seven bacterial symbionts of the nematodes steinernema spp. which were isolated from different geographical areas, as well as the type strain of xenorhabdus japonicus, were determined and compared to each other and to the sequences of several reference strains of members of the enterobacteriaceae. the data confirmed the separate status of the two genera of symbionts of ent ... | 1997 | 9103628 |
| the construction and application of a lux-based nitrate biosensor. | a plasmid-borne transcriptional fusion between the escherichia coli nitrate reductase (narg) promoter and the photorhabdus luminescens lux operon provides e. coli with a highly bioluminescent phenotype in the presence of nitrate. this e. coli biosensor can detect nitrate to a level of 5 x 10(-5) mol l-1 (0.3 ppm), levels relevant to those levels encountered in brewing water. since induction of the narg promoter requires narl, the plasmid-based sensor can also be used to interrogate enteric bacte ... | 1997 | 9172442 |
| analysis of proteins from different phase variants of the entomopathogenic bacteria photorhabdus luminescens by two-dimensional zymography. | two-dimensional zymography which combines two-dimensional electrophoresis with zymography was used to analyze proteases and other proteins produced by different phase variants of two strains of photorhabdus luminescens. both the primary and secondary phases of p. luminescens strains hp and hm secreted proteases. the protease in p. luminescens hp has a molecular weight (mr) of 57,000 and an isoelectric point (pi) of 4.4 whereas that in p. luminescens hm has an mr of 59,000 and pi of 4.9. several ... | 1997 | 9194616 |
| phylogeny of photorhabdus and xenorhabdus species and strains as determined by comparison of partial 16s rrna gene sequences. | partial 16s rrna gene sequences of 16 strains of the genera photorhabdus and xenorhabdus were determined by direct sequencing of pcr products. aligned sequences were subjected to phylogenetic analysis by maximum-likelihood and maximum-parsimony methods. distance matrix and phylogenetic analysis did not separate the genera unambiguously. taxonomic grouping of the bacteria closely paralleled taxonomic grouping of their nematode associates and their geographic origins. we found at least two well-su ... | 1997 | 9336891 |
| xenorhabdus and photorhabdus spp.: bugs that kill bugs. | xenorhabdus and photorhabdus spp. are gram negative gamma proteobacteria that form entomopathogenic symbioses with soil nematodes. they undergo a complex life cycle that involves a symbiotic stage, in which the bacteria are carried in the gut of the nematodes, and a pathogenic stage, in which susceptible insect prey are killed by the combined action of the nematode and the bacteria. both bacteria produce antibiotics, intracellular protein crystals, and numerous other products. these traits chang ... | 1997 | 9343343 |
| quantitative analysis of a bacteria-derived antibiotic in nematode-infected insects using hplc-uv and tlc-uv methods. | 3,5-dihydroxy-4-isopropylstilbene (st), an antibiotic produced by the bacterial symbiont photorhabdus luminescens of the nematodes of the genus heterorhabditis was determined quantitatively in nematode bacterium-infected insects using hplc or tlc for separation and uv for quantification. comparable and reproducible results were obtained with both hplc-uv and tlc-uv methods. several factors, including solvents for extraction of the antibiotic from the infected insects, eluents for tlc development ... | 1997 | 9448074 |
| constricted flux through the branched-chain amino acid biosynthetic enzyme acetolactate synthase triggers elevated expression of genes regulated by rpos and internal acidification. | the first common enzyme of isoleucine and valine biosynthesis, acetolactate synthase (als), is specifically inhibited by the herbicide sulfometuron methyl (sm). to further understand the physiological consequences of flux alterations at this point in metabolism, escherichia coli genes whose expression was induced by partial inhibition of als were sought. plasmid-based fusions of random e. coli dna fragments to photorhabdus luminescens luxcdabe were screened for bioluminescent increases in active ... | 1998 | 9473030 |
| insertional inactivation of genes encoding the crystalline inclusion proteins of photorhabdus luminescens results in mutants with pleiotropic phenotypes. | the entomopathogenic bacterium photorhabdus luminescens exhibits phase variation when cultured in vitro. the variant forms of p. luminescens are pleiotropic and are designated phase i and phase ii variants. one of the characteristic phenotypes of phase i cells is the production of two types of intracellular protein inclusions. the genes encoding the protein monomers that form these inclusions, designated cipa and cipb, were cloned and characterized. cipa and cipb encode hydrophobic proteins of 1 ... | 1998 | 9495767 |
| bioluminescence as a reporter of intracellular survival of bordetella bronchiseptica in murine phagocytes. | the uptake and persistence of bordetella bronchiseptica was characterized in murine phagocytes by using a novel bioluminescence-based reporter system. a mini-tn5 promoter probe carrying the intact lux operon from the terrestrial bacterium photorhabdus luminescens which allowed measurement of light output without the addition of exogenous substrate was constructed. it was used to create a pool of bioluminescent fusion strains of b. bronchiseptica. the internalization and persistence in murine mac ... | 1998 | 9632586 |
| insecticidal toxins from the bacterium photorhabdus luminescens. | transgenic plants expressing bacillus thuringiensis (bt) toxins are currently being deployed for insect control. in response to concerns about bt resistance, we investigated a toxin secreted by a different bacterium photorhabdus luminescens, which lives in the gut of entomophagous nematodes. in insects infected by the nematode, the bacteria are released into the insect hemocoel; the insect dies and the nematodes and bacteria replicate in the cadaver. the toxin consists of a series of four native ... | 1998 | 9641921 |
| isolation and entomotoxic properties of the xenorhabdus nematophilus f1 lecithinase. | xenorhabdus spp. and photorhabdus spp., entomopathogenic bacteria symbiotically associated with nematodes of the families steinernematidae and heterorhabditidae, respectively, were shown to produce different lipases when they were grown on suitable nutrient agar. substrate specificity studies showed that photorhabdus spp. exhibited a broad lipase activity, while most of the xenorhabdus spp. secreted a specific lecithinase. xenorhabdus spp. occur spontaneously in two variants, phase i and phase i ... | 1998 | 9647801 |
| the apee gene of salmonella typhimurium encodes an outer membrane esterase not present in escherichia coli. | salmonella typhimurium aper mutations lead to overproduction of an outer membrane-associated n-acetyl phenylalanine beta-naphthyl ester-cleaving esterase that is encoded by the apee gene (p. collin-osdoby and c. g. miller, mol. gen. genet. 243:674-680, 1994). this paper reports the cloning and nucleotide sequencing of the s. typhimurium apee gene as well as some properties of the esterase that it encodes. the predicted product of apee is a 69.9-kda protein which is processed to a 67-kda species ... | 1998 | 9657991 |
| engineering the luxcdabe genes from photorhabdus luminescens to provide a bioluminescent reporter for constitutive and promoter probe plasmids and mini-tn5 constructs. | the luxcdabe operon of photorhabdus luminescens has been cloned and engineered as an easily mobilisable cassette flanked by sites for commonly used restriction enzymes. constitutive and promoter probe plasmids utilising the p. luminescens luxcdabe have been constructed using a number of compatible replicons and antibiotic markers. complementary to these plasmids, a range of promoterless and constitutive luxcdabe mini-tn5 derivatives has been constructed. the potential of coupling mini-tn5 luxcda ... | 1998 | 9673022 |
| photorhabdus luminescens luxcdabe promoter probe vectors. | | 1998 | 9680611 |
| purification and characterization of a high-molecular-weight insecticidal protein complex produced by the entomopathogenic bacterium photorhabdus luminescens | photorhabdus luminescens is a gram-negative enteric bacterium that is found in association with entomopathogenic nematodes of the family heterorhabditidae. the nematodes infect a variety of soil-dwelling insects. upon entering an insect host, the nematode releases p. luminescens cells from its intestinal tract, and the bacteria quickly establish a lethal septicemia. when grown in peptone broth, in the absence of the nematodes, the bacteria produce a protein toxin complex that is lethal when fed ... | 1998 | 9687469 |
| a novel insecticidal toxin from photorhabdus luminescens, toxin complex a (tca), and its histopathological effects on the midgut of manduca sexta | photorhabdus luminescens is a bacterium which is mutualistic with entomophagous nematodes and which secretes high-molecular-weight toxin complexes following its release into the insect hemocoel upon nematode invasion. thus, unlike other protein toxins from bacillus thuringiensis (delta-endotoxins and vip's), p. luminescens toxin (pht) normally acts from within the insect hemocoel. unexpectedly, therefore, the toxin complex has both oral and injectable activities against a wide range of insects. ... | 1998 | 9687470 |
| in vitro and in vivo characterization of a small-colony variant of the primary form of photorhabdus luminescens md (enterobacteriaceae) | a small-colony variant (vsm) of the primary form (vp) of photorhabdus luminescens md from in vitro and in vivo cultures is described. unlike the primary form, vp, the vsm variant is not the preferred diet of its nematode symbiont, a heterorhabditis sp., does not support development and reproduction of the nematode, and is less pathogenic than vp to galleria mellonella larvae. vsm cells were carried by 25% of infective juveniles, but they comprised a very low percentage ( approximately 0.4%) of t ... | 1998 | 9726862 |
| calcium binding by the n-terminal cellulose-binding domain from cellulomonas fimi beta-1,4-glucanase cenc. | the interaction of the n-terminal cellulose-binding domain, cbdn1, from cellulomonas fimi beta-1,4-glucanase cenc with calcium was investigated using nmr spectroscopy and calorimetry. cbdn1 binds a single calcium ion with an equilibrium association constant of approximately 10(5) m-1 at 35 degreesc and ph 6.0. binding is exothermic (-42 +/- 2 kj mol-1) under these conditions and is accompanied by a small negative change in heat capacity (deltacp = -0.41 +/- 0.16 kj mol-1 k-1). from an nmr line s ... | 1998 | 9737854 |
| active resistance of entomophagous rhabditid heterorhabditis bacteriophora to insect immunity. | a specific extracellular proteinase, degrading selectively the cecropin-based defence system of insects, is secreted into the larval body during parasitism of the greater wax moth by the heterorhabditis bacteriophora/photorhabdus luminescens complex and by phase 1 of p. luminescens. the proteolytic digestion of insect inducible cecropin-like immune molecules was demonstrated by the disappearance of the galleria mellonella cecropins and purified hyalophora cecropin b peptide page bands upon expos ... | 1998 | 9774783 |
| pcr-ribotyping of xenorhabdus and photorhabdus isolates from the caribbean region in relation to the taxonomy and geographic distribution of their nematode hosts. | the genetic diversity of symbiotic xenorhabdus and photorhabdus bacteria associated with entomopathogenic nematodes was examined by a restriction fragment length polymorphism analysis of pcr-amplified 16s rrna genes (rdnas). a total of 117 strains were studied, most of which were isolated from the caribbean basin after an exhaustive soil sampling. the collection consisted of 77 isolates recovered from entomopathogenic nematodes in 14 caribbean islands and of 40 reference strains belonging to xen ... | 1998 | 9797272 |
| a recombinant escherichia coli sensor strain for the detection of tetracyclines. | a bioluminescent escherichia coli k-12 strain for the specific detection of the tetracycline group of antibiotics is described. a sensor plasmid, containing five genes from bacterial luciferase operon of photorhabdus luminescens inserted under the control of tetracycline-responsive elements of the transposon tn10, was constructed. usage of the full-length luciferase operon in the sensor resulted in tetracycline-dependent light production without additions, i.e., self-luminescent phenotype, since ... | 1998 | 9823708 |
| molecular identification of photorhabdus luminescens strains by amplification of specific fragments of the 16s ribosomal dna. | sequence variation within the variable region of the 16s rrna at position 440 to 480 allowed the synthesis of specific pcr primers for the identification of groups within the species photorhabdus luminescens, symbionts of entomopathogenic nematodes of the genus heterorhabditis. for the second pcr primer the highly conserved region at 755 to 795 was used. the p. luminescens type strain specific primer could not recognize any other p. luminescens strain. the primer temperatus based on the sequence ... | 1998 | 9924819 |
| successful parasitation of locusts by entomopathogenic nematodes is correlated with inhibition of insect phagocytes. | the entomopathogenic nematodes heterorhabditis megidis and steinernema feltiae turned out to be successful antagonists of the orthopteran insects locusta migratoria and schistocerca gregaria. the death rate of locusts maintained on nematode-inoculated sand was remarkably high. even dosages as low as one nematode per cubic centimeter of sand killed approximately 50% of the locusts within 10 days. the impact of parasitation on locusts' immune defense was closely investigated for l. migratoria para ... | 1999 | 10066395 |
| photorhabdus luminescens w-14 insecticidal activity consists of at least two similar but distinct proteins. purification and characterization of toxin a and toxin b. | both the bacterium photorhabdus luminescens alone and its symbiotic photorhabdus-nematode complex are known to be highly pathogenic to insects. the nature of the insecticidal activity of photorhabdus bacteria was investigated for its potential application as an insect control agent. it was found that in the fermentation broth of p. luminescens strain w-14, at least two proteins, toxin a and toxin b, independently contributed to the oral insecticidal activity against southern corn rootworm. purif ... | 1999 | 10092674 |
| folding and refolding of thermolabile and thermostable bacterial luciferases: the role of dnakj heat-shock proteins. | bacterial luciferases are highly suitable test substrates for the analysis of refolding of misfolded proteins, as they are structurally labile and loose activity at 42 degrees c. heat-denatured thermolabile vibrio fischeri luciferase and thermostable photorhabdus luminescens luciferase were used as substrates. we found that their reactivation requires the activity of the dnak chaperone system. the dnakj chaperones were dispensable in vivo for de novo folding at 30 degrees c of the luciferase, bu ... | 1999 | 10218489 |
| antimicrobial properties and morphological characteristics of two photorhabdus luminescens strains. | the biological properties of two photorhabdus luminescens isolates (mu1 and mu2) of environmental source and the activity of antimicrobial agar diffusible agents (aada) produced by the same are reported. with regard to cultural features, two variant forms for p. luminescens mu1 and three for p. luminescens mu2 (including an intermediate phase i-like form) have been found. these three forms differ in biological and biochemical properties: beta-lactamase, urease, bioluminescence and antimicrobial ... | 1999 | 10322611 |
| stimulation of no synthase activity in the immune-competent lepidopteran estigmene acraea hemocyte line. | in contrast to the vertebrate immune system, nearly nothing is known about the immunological role of nitric oxide (no) in invertebrates. this study provides evidence of the presence of a no synthase (nos) activity in an immune-competent, macrophage-like insect hemocyte line, previously established from larvae of the lepidopteran insect estigmene acraea. as proven by photometric determination of nitroblue tetrazolium reduction after cell fixation, the e. acraea cells possess nadph diaphorase (nad ... | 1999 | 10369182 |
| photorhabdus toxins: novel biological insecticides. | following concerns over the potential for insect resistance to insecticidal bacillus thuringiensis toxins expressed in transgenic plants, there has been recent interest in novel biological insecticides. over the past year there has been considerable progress in the cloning of several alternative toxin genes from the bacteria photorhabdus luminescens and xenorhabdus nematophilus. these genes encode large insecticidal toxin complexes with little homology to other known toxins. | 1999 | 10383860 |
| survival of insect pathogenic and human clinical isolates of photorhabdus luminescens in previously sterile soil. | most characterized strains of the bacterium photorhabdus luminescens are symbionts of entomopathogenic nematodes, whereas other strains have been isolated from human clinical specimens. the ability of p. luminescens strains to survive and grow in soil has received limited attention, with some studies indicating these bacteria have little or no ability to persist in soil. survival and (or) growth of p. luminescens strains in previously sterilized soil, and examination of different soil amendments ... | 1999 | 10408101 |
| isolation, identification, and molecular characterization of strains of photorhabdus luminescens from infected humans in australia. | we describe the isolation of photorhabdus (xenorhabdus) luminescens from four australian patients: two with multiple skin lesions, one with bacteremia only, and one with disseminated infection. one of the patients had multiple skin lesions following the bite of a spider, while the lesions in the other patient were possibly associated with a spider bite. the source of infection for the remaining two patients is unknown. as a member of the family enterobacteriaceae, p. luminescens is unusual in th ... | 1999 | 10523568 |
| control of luminescence decay and flavin binding by the luxa carboxyl-terminal regions in chimeric bacterial luciferases. | bacterial luciferases (luxab) can be readily classed as slow or fast decay luciferases based on their rates of luminescence decay in a single turnover assay. luciferases from vibrio harveyi and xenorhabdus (photorhabdus) luminescens have slow decay rates, and those from the photobacterium genus, such as p. (vibrio) fischeri, p. phosphoreum, and p. leiognathi, have rapid decay rates. by generation of an x. luminescens-based chimeric luciferase with a 67 amino acid substitution from p. phosphoreum ... | 1999 | 10529227 |
| the phylogenetic position of serratia, buttiauxella and some other genera of the family enterobacteriaceae. | the phylogenetic relationships of the type strains of 38 species from 15 genera of the family enterobacteriaceae were investigated by comparative 16s rdna analysis. several sequences of strains from the genera citrobacter, erwinia, pantoea, proteus, rahnella and serratia, analysed in this study, have been analysed previously. however, as the sequences of this study differ slightly from the published ones, they were included in the analysis. of the 23 enterobacterial genera included in an overvie ... | 1999 | 10555323 |
| polyphasic classification of the genus photorhabdus and proposal of new taxa: p. luminescens subsp. luminescens subsp. nov., p. luminescens subsp. akhurstii subsp. nov., p. luminescens subsp. laumondii subsp. nov., p. temperata sp. nov., p. temperata subsp. temperata subsp. nov. and p. asymbiotica sp. nov. | the taxonomic position of photorhabdus strains was examined through the results of dna relatedness (s1 nuclease method) studies associated with the determination of delta tm, 16s rrna phylogenetic inferences and phenotypic characterization, including morphological, auxanographic, biochemical and physiological properties. three genomic species were delineated on a consensus assessment. one of these species corresponded to photorhabdus luminescens, since strains were at least 50% related to the ty ... | 1999 | 10555346 |
| pathogenicity, development, and reproduction of heterorhabditis bacteriophora and steinernema carpocapsae under axenic in vivo conditions. | galleria mellonella larvae cultured axenically were treated with axenic dauer juveniles of heterorhabditis bacteriophora and steinernema carpocapsae. after 3 days s. carpocapsae had killed all insects, with 9.4 +/- 4.3 nematodes per larva. h. bacteriophora were unable to kill g. mellonella, although 13.3 +/- 6.4 nematodes per galleria were found in the hemocoel. invading nematodes of both strains recovered from the dauer stage. h. bacteriophora developed into hermaphrodites with eggs and j1 in t ... | 2000 | 10631058 |
| secreted proteases from photorhabdus luminescens: separation of the extracellular proteases from the insecticidal tc toxin complexes. | photorhabdus luminescens secretes both high molecular weight insecticidal toxin complexes and also a range of extracellular proteases into culture broth. previous studies by others have suggested that insecticidal activity of the broth is associated with these proteases. however, by gene cloning and targeted knock-out, we have previously shown that oral insecticidal activity is associated with high molecular weight 'toxin complexes' (tc) encoded by toxin complex or tc genes. here we further clar ... | 2000 | 10646972 |
| deficiency of current methods in assaying endochitinase activity. | since chitin is degraded by a combination of both endo- and exochitinases, it is likely that both enzymes will be present in a crude extract. currently used substrates for detecting endochitinase activity suffer from the fact that they could easily be digested by the contaminating exochitinase, thus giving either a false-positive or an inaccurate reading of the endochitinase activity. using photorhabdus luminescens, a bacterium symbiotically associated with insect-parasitic nematode heterorhabdi ... | 2000 | 10679198 |
| occurrence of natural dixenic associations between the symbiont photorhabdus luminescens and bacteria related to ochrobactrum spp. in tropical entomopathogenic heterorhabditis spp. (nematoda, rhabditida). | bacteria naturally associated with the symbiont photorhabdus luminescens subsp. akhurstii were isolated from the entomopathogenic nematode heterorhabditis indica. bacterial isolates distinct from p. luminescens subsp. akhurstii were obtained from 33% of the samples. fourteen bacterial isolates, from nematodes collected from three different caribbean islands, were characterized by conventional phenotypic tests, restriction fragment length polymorphism and sequence analyses of pcr-amplified 16s rr ... | 2000 | 10746775 |
| improved bacterial sos promoter:lux fusions for genotoxicity detection. | escherichia coli strains containing plasmid-borne fusions of vibrio fischeri lux to the reca promoter-operator region were previously shown to be potentially useful for detecting genotoxicants. in an attempt to improve past performance, the present study examines several modifications and variations of this design, singly or in various combinations: (1) modifying the host cell's toxicant efflux capacity via a tolc mutation; (2) incorporating the lux fusion onto the bacterial chromosome, rather t ... | 2000 | 10751731 |
| [cloning and expression of the lux-operon of photorhabdus luminescens, strain zm1: nucleotide sequence of luxab genes and basic properties of luciferase]. | a chromosomal fragment of bacteria photorhabdus luminescence zm1, which contains the lux operon, was cloned into the vector puc18. the hybrid clone containing plasmid pxen7 with the ecori fragment approximately 7-kb was shown to manifest a high level of bioluminescence. by subcloning and restriction analysis of the ecori fragment, the location of luxcdabe genes relative to restriction sites was determined. the nucleotide sequence of the dna fragment containing the luxa and luxb genes encoding al ... | 2000 | 10779906 |
| a streptavidin-luciferase fusion protein: comparisons and applications. | luciferases are unique enzymes in being capable of emitting visible light as one of the end-products of their catalysis. both procaryotic and eucaryotic organisms exist that emit light, and the luciferases from these organisms differ considerably in size as well as chemistry of catalysis. two main, i.e. most studied groups, are the bacterial luciferases of e.g. vibrio fisheri, vibrio harveyi, and photorhabdus luminescens, responding to fmnh2, long-chain aldehyde and molecular oxygen and the inse ... | 1999 | 10796991 |
| monitoring bioluminescent staphylococcus aureus infections in living mice using a novel luxabcde construct. | strains of staphylococcus aureus were transformed with plasmid dna containing a photorhabdus luminescens lux operon (luxabcde) that was genetically modified to be functional in both gram-positive and gram-negative bacteria. s. aureus cells containing this novel lux construct, downstream of an appropriate promoter sequence, are highly bioluminescent, allowing the detection of fewer than 100 cfu in vitro (direct detection of exponentially dividing cells in liquid culture). furthermore, these bacte ... | 2000 | 10816517 |
| novel insecticidal toxins from nematode-symbiotic bacteria. | the current strategy of using transgenic crops expressing insecticidal protein toxins is placing increasing emphasis on the discovery of novel toxins, beyond those already derived from the bacterium bacillus thuringiensis. here we review the cloning of four insecticidal toxin complex (tc) encoding genes from a different bacterium photorhabdus luminescens and of similar gene sequences from xenorhabdus nematophilus. both these bacteria occupy the gut of entomopathogenic nematodes and are released ... | 2000 | 10892346 |
| ecotoxicological testing with new kinetic photorhabdus luminescens growth and luminescence inhibition assays in microtitration scale | miniaturized luminescence and growth inhibition assays in microtitration plates with the terrestric enthomopathogenic nematode symbiont photorhabdus luminescens (dsmz 3368t) are presented and compared with standardized tests with vibrio fischeri (dsmz 7151/nrrlb-11177) and pseudomonas putida (dsmz 50026). toxicological parameters (ec and g values) of selected reference toxicants (e.g. heavy metals and environmental samples) were obtained at different temperatures and without sodium chloride supp ... | 1999 | 10903092 |
| a genomic sample sequence of the entomopathogenic bacterium photorhabdus luminescens w14: potential implications for virulence. | photorhabdus luminescens is a pathogenic bacterium that lives in the guts of insect-pathogenic nematodes. after invasion of an insect host by a nematode, bacteria are released from the nematode gut and help kill the insect, in which both the bacteria and the nematodes subsequently replicate. however, the bacterial virulence factors associated with this "symbiosis of pathogens" remain largely obscure. in order to identify genes encoding potential virulence factors, we performed approximately 2,00 ... | 2000 | 10919786 |
| antibiotic production in relation to bacterial growth and nematode development in photorhabdus--heterorhabditis infected galleria mellonella larvae. | the population of photorhabdus luminescens c9, bacterial symbiont of the entomopathogenic nematode, heterorhabditis megidis 90, increased rapidly to 1.2-2.6x10(9) cells g(-1) wet galleria mellonella larvae within 24 h of nematode infection of the larvae, and maintained a relatively constant level (1.2-2.0x10(10) cells g(-1)) through the entire 14-day period of nematode development. the antibiotic, 3, 5-dihydroxy-4-isopropylstilbene, was produced by p. luminescens c9 after 24 h of nematode infect ... | 2000 | 10930742 |
| influence of the aeration rate on the yields of the biocontrol nematode heterorhabditis megidis in monoxenic liquid cultures. | the entomopathogenic nematode-bacterium complex heterorhabditis megidis photorhabdus luminescens was cultured in 10-1 internal loop bioreactors with marine impellers at aeration rates of 0.3 vvm and 0.7 vvm. process parameters like impeller velocity and oxygen saturation were controlled at equal set points. the bacterial density was assessed at 24 h. nematode dauer juveniles (dj) were then inoculated and the development to adults after 8 days and final dj yields after 16 days were recorded. the ... | 2000 | 10951998 |
| a group-specific microbiological test for the detection of tetracycline residues in raw milk. | the potentiality of using a luminescent escherichia coli strain for the specific detection of tetracycline residues in raw bovine milk was investigated. the sensor cells contain a reporter plasmid carrying the bacterial luciferase operon of photorhabdus luminescens under the control of the tetracycline responsive control region from transposon tn10. incubation of the cells with the sample containing tetracyclines increases the light emission of the sensor cells. the most sensitive tetracycline d ... | 2000 | 10956118 |
| plasmid-located pathogenicity determinants of serratia entomophila, the causal agent of amber disease of grass grub, show similarity to the insecticidal toxins of photorhabdus luminescens. | serratia entomophila and serratia proteamaculans cause amber disease in the grass grub costelytra zealandica (coleoptera: scarabaeidae), an important pasture pest in new zealand. larval disease symptoms include cessation of feeding, clearance of the gut, amber coloration, and eventual death. a 115-kb plasmid, padap, identified in s. entomophila is required for disease causation and, when introduced into escherichia coli, enables that organism to cause amber disease. a 23-kb fragment of padap tha ... | 2000 | 10960097 |
| the predicted structure of photopexin from photorhabdus shows the first haemopexin-like motif in prokaryotes. | the insect pathogenic bacterium photorhabdus luminescens secretes several insecticidal high molecular mass 'toxin complexes'. analysis of the putative pathogenicity island surrounding the toxin complex a (tca) locus revealed two open reading frames (orfs) of unknown function. the predicted protein sequences of these orfs show a repeated motif similar to those found in the vertebrate haem scavenging molecule haemopexin, limunectin (a phosphocholine binding protein from limulus) and the c-terminal ... | 2000 | 11004411 |
| growth of photorhabdus luminescens in batch and glucose fed-batch culture. | photorhabdus luminescens, a bacterial symbiont of entomopathogenic biocontrol nematodes, was grown in batch and glucose fed-batch culture. the cell density, bioluminescence, production of antibiotic substances, number of cells with inclusion bodies, glucose concentration and oxygen uptake rate were recorded. the addition of 12.4 g 1(-1) glucose prolonged the growth, and the yield almost doubled, from 6.85 g 1(-1) to 12.45 g 1(-1) dry mass. the production of antibiotic substances increased by 140 ... | 2000 | 11030567 |
| detection of tetracyclines with luminescent bacterial strains. | the performance of two bioluminescent escherichia coli k-12 strains for the specific detection of the tetracycline family of antimicrobial agents was compared, and the analytical applicability of one of the strains was preliminarily evaluated. one sensor plasmid contained the bacterial luciferase operon of photorhabdus luminescens under the control of the tetracycline-responsive element from transposon tn10 (15). an analogous plasmid construction with firefly (photinus pyralis) luciferase report ... | 2000 | 11038486 |
| a new broad-spectrum protease inhibitor from the entomopathogenic bacterium photorhabdus luminescens. | a new protease inhibitor was purified to apparent homogeneity from a culture medium of photorhabdus luminescens by ammonium sulfate precipitation and preparative isoelectric focusing followed by affinity chromatography. ph. luminescens, a bacterium symbiotically associated with the insect-parasitic nematode heterorhabditis bacteriophora, exists in two morphologically distinguishable phases (primary and secondary). it appears that only the secondary-phase bacterium produces this protease inhibito ... | 2000 | 11101672 |
| validation of a noninvasive, real-time imaging technology using bioluminescent escherichia coli in the neutropenic mouse thigh model of infection. | a noninvasive, real-time detection technology was validated for qualitative and quantitative antimicrobial treatment applications. the lux gene cluster of photorhabdus luminescens was introduced into an escherichia coli clinical isolate, ec14, on a multicopy plasmid. this bioluminescent reporter bacterium was used to study antimicrobial effects in vitro and in vivo, using the neutropenic-mouse thigh model of infection. bioluminescence was monitored and measured in vitro and in vivo with an inten ... | 2001 | 11120955 |
| liquid media development for heterorhabditis bacteriophora: lipid source and concentration. | lipids are important entomopathogenic nematode nutritional components because they are energy reserves and serve as indicators of nematode quality. the composition and concentration of the media lipid component determine bacterial and nematode yields. heterorhabditis bacteriophora and its symbiont, photorhabdus luminescens, were cultured in media containing various lipid sources. as lipid concentration increased from 2.5% to 8.0% (w/v), the final yield and productivity [calculated from the numbe ... | 2000 | 11152066 |
| microbial sensors of ultraviolet radiation based on reca'::lux fusions. | escherichia coli strains containing plasmid-borne fusions of the reca promoter-operator region to the vibrio fischeri lux genes were previously shown to increase their luminescence in the presence of dna damage hazards, and thus to be useful for genotoxicant detection. the present study expands previous work by demonstrating and investigating the luminescent response of these strains to ultraviolet radiation. several genetic variants of the basic reca'::lux design were examined, including a tolc ... | 2000 | 11209459 |
| a genomic approach to gene fusion technology. | gene expression profiling provides powerful analyses of transcriptional responses to cellular perturbation. in contrast to dna array-based methods, reporter gene technology has been underused for this application. here we describe a genomewide, genome-registered collection of escherichia coli bioluminescent reporter gene fusions. dna sequences from plasmid-borne, random fusions of e. coli chromosomal dna to a photorhabdus luminescens luxcdabe reporter allowed precise mapping of each fusion. the ... | 2001 | 11226277 |
| identification of symbiotic bacteria (photorhabdus and xenorhabdus) from the entomopathogenic nematodes heterorhabditis marelatus and steinernema oregonense based on 16s rdna sequence. | two species of entomopathogenic nematodes, heterorhabditis marelatus and steinernema oregonense, were described recently from the west coast of north america. it is not known whether the bacterial symbionts of these nematodes are also unique. here we compared partial 16s rrna sequences from the symbiotic bacteria of these two nematodes with sequence from previously described photorhabdus and xenorhabdus species. the 16s sequence from the new xenorhabdus isolate appears very similar to, although ... | 2001 | 11273687 |
| the tc genes of photorhabdus: a growing family. | the toxin complex (tc) genes of photorhabdus encode insecticidal, high molecular weight tc toxins. these toxins have been suggested as useful alternatives to those derived from bacillus thuringiensis for expression in insect-resistant transgenic plants. although photorhabdus luminescens is symbiotic with nematodes that kill insects, tc genes have recently been described from other insect-associated bacteria such as serratia entomophila, an insect pathogen, and yersinia pestis, the causative agen ... | 2001 | 11286884 |
| effect of photorhabdus luminescens phase variants on the in vivo and in vitro development and reproduction of the entomopathogenic nematodes heterorhabditis bacteriophora and steinernema carpocapsae. | photorhabdus luminescens (enterobacteriaceae) is a symbiont of entomopathogenic nematodes heterorhabditis spp. (nematoda: rhabditida) used for biological control of insect pests. for industrial mass production, the nematodes are produced in liquid media, pre-incubated with their bacterial symbiont, which provides nutrients essential for the nematode's development and reproduction. particularly under in vitro conditions, p. luminescens produces phase variants, which do not allow normal nematode d ... | 2001 | 11311434 |
| sequence analysis of insecticidal genes from xenorhabdus nematophilus pmfi296. | three strains of xenorhabdus nematophilus showed insecticidal activity when fed to pieris brassicae (cabbage white butterfly) larvae. from one of these strains (x. nematophilus pmfi296) a cosmid genome library was prepared in escherichia coli and screened for oral insecticidal activity. two overlapping cosmid clones were shown to encode insecticidal proteins, which had activity when expressed in e. coli (50% lethal concentration [lc(50)] of 2 to 6 microg of total protein/g of diet). the complete ... | 2001 | 11319082 |
| a phosphopantetheinyl transferase homolog is essential for photorhabdus luminescens to support growth and reproduction of the entomopathogenic nematode heterorhabditis bacteriophora. | the bacterium photorhabdus luminescens is a symbiont of the entomopathogenic nematode heterorhabditis bacteriophora. the nematode requires the bacterium for infection of insect larvae and as a substrate for growth and reproduction. the nematodes do not grow and reproduce in insect hosts or on artificial media in the absence of viable p. luminescens cells. in an effort to identify bacterial factors that are required for nematode growth and reproduction, transposon-induced mutants of p. luminescen ... | 2001 | 11325940 |
| two distinct hemolytic activities in xenorhabdus nematophila are active against immunocompetent insect cells. | xenorhabdus spp. and photorhabdus spp. are major insect bacterial pathogens symbiotically associated with nematodes. these bacteria are transported by their nematode hosts into the hemocoel of the insect prey, where they proliferate within hemolymph. in this work we report that wild strains belonging to different species of both genera are able to produce hemolysin activity on blood agar plates. using a hemocyte monolayer bioassay, cytolytic activity against immunocompetent cells from the hemoly ... | 2001 | 11375158 |
| description and application of a rapid method for genomic dna direct sequencing. | we describe a rapid method for determining nucleotide sequences directly from total genomic dna. this technique was used to determine genomic dna sequences in various prokaryotic and eukaryotic microorganisms with a g+c content between 40 and 50%, e.g. escherichia coli, vibrio cholerae, bacillus subtilis and saccharomyces cerevisiae. furthermore, the method was applied to accurately sequence up to 300 dna base pairs in photorhabdus luminescens, whose genome sequencing is currently under way. tak ... | 2001 | 11377872 |
| luxarray, a high-density, genomewide transcription analysis of escherichia coli using bioluminescent reporter strains. | a sequenced collection of plasmid-borne random fusions of escherichia coli dna to a photorhabdus luminescens luxcdabe reporter was used as a starting point to select a set of 689 nonredundant functional gene fusions. this group, called luxarray 1.0, represented 27% of the predicted transcriptional units in e. coli. high-density printing of the luxarray 1.0 reporter strains to membranes on agar plates was used for simultaneous reporter gene assays of gene expression. the cellular response to nali ... | 2001 | 11544210 |
| measuring virulence factor expression by the pathogenic bacterium photorhabdus luminescens in culture and during insect infection. | during insect infection photorhabdus luminescens emits light and expresses virulence factors, including insecticidal toxin complexes (tcs) and an rtx-like metalloprotease (prt). using quantitative pcr and protein assays, we describe the expression patterns of these factors both in culture and during insect infection and compare them to the associated bacterial growth curves. in culture, light and active prt protease are produced in stationary phase. tca also appears in stationary phase, whereas ... | 2001 | 11566980 |
| isolation and characterization of intracellular protein inclusions produced by the entomopathogenic bacterium photorhabdus luminescens. | cells of the entomopathogenic bacterium photorhabdus luminescens contain two types of morphologically distinct crystalline inclusion proteins. the larger rectangular inclusion (type 1) and a smaller bipyramid-shaped inclusion (type 2) were purified from cell lysates by differential centrifugation and isopycnic density gradient centrifugation. both structures are composed of protein and are readily soluble at ph 11 and 4 in 1% sodium dodecyl sulfate (sds) and in 8 m urea. electrophoretic analysis ... | 2001 | 11571191 |
| mass production of entomopathogenic nematodes for plant protection. | entomopathogenic nematodes of the genera heterorhabditis and steinernema are commercially used to control pest insects. they are symbiotically associated with bacteria of the genera photorhabdus and xenorhabdus, respectively, which are the major food source for the nematodes. the biology of the nematode-bacterium complex is described, a historical review of the development of in vitro cultivation techniques is given and the current use in agriculture is summarised. cultures of the complex are pr ... | 2001 | 11601608 |
| use of bioluminescent salmonella for assessing the efficiency of constructed phage-based biosorbent. | a bacteriophage-based biosorbent for salmonella enteritidis was constructed, and bacterial bioluminescence was used for assessment of the efficiency of cell capture. a strain of s. enteritidis with bioluminescent phenotype was constructed by transformation with plasmid pt7 carrying the entire lux operon from photorhabdus luminescens. the relation between relative light output (rlu) and colony-forming units (cfu/ml) of the bioluminescent strain was established. the bacteriophage specific to s. en ... | 2001 | 11641771 |
| oral toxicity of photorhabdus luminescens w14 toxin complexes in escherichia coli. | previous attempts to express the toxin complex genes of photorhabdus luminescens w14 in escherichia coli have failed to reconstitute their oral toxicity to the model insect manduca sexta. here we show that the combination of three genes, tcda, tcdb, and tccc, is essential for oral toxicity to m. sexta when expression in e. coli is used. further, when transcription from native toxin complex gene promoters is used, maximal toxicity in e. coli cultures is associated with the addition of mitomycin c ... | 2001 | 11679320 |
| expression of lux genes in a clinical isolate of streptococcus pneumoniae: using bioluminescence to monitor gemifloxacin activity. | a clinical isolate of streptococcus pneumoniae was transformed with a plasmid containing the lux operon of photorhabdus luminescens that had been modified to function in gram-positive bacteria. cells containing this plasmid produced light stably and constitutively, without compromising the growth rate. light output was correlated with measurements of optical density and viable counts during exponential growth and provided a sensitive, real-time measure of the pharmacodynamics of the fluoroquinol ... | 2002 | 11796373 |
| reporter genes lucff, luxcdabe, gfp, and dsred have different characteristics in whole-cell bacterial sensors. | the selection of a genetic reporter can be difficult because of the wide range of genes available. in order to reduce the selection, we compared the performance of different reporter genes: firefly luciferase (photinus pyralis lucff), bacterial luciferase operon (photorhabdus luminescens luxcdabe), green fluorescent protein (aequorea victoria gfp), and red fluorescent protein (discosoma sp. dsred) in whole-cell bacterial sensors. escherichia coli sensor bacteria were engineered to contain a repo ... | 2002 | 11814294 |
| imaging of light emission from the expression of luciferases in living cells and organisms: a review. | luciferases are enzymes that emit light in the presence of oxygen and a substrate (luciferin) and which have been used for real-time, low-light imaging of gene expression in cell cultures, individual cells, whole organisms, and transgenic organisms. such luciferin-luciferase systems include, among others, the bacterial lux genes of terrestrial photorhabdus luminescens and marine vibrio harveyi bacteria, as well as eukaryotic luciferase luc and ruc genes from firefly species (photinus) and the se ... | 2002 | 11816060 |
| rapid control of wound infections by targeted photodynamic therapy monitored by in vivo bioluminescence imaging. | the worldwide rise in antibiotic resistance necessitates the development of novel antimicrobial strategies. in this study we report on the first use of a photochemical approach to destroy bacteria infecting a wound in an animal model. following topical application, a targeted polycationic photosensitizer conjugate between poly-l-lysine and chlorin(e6) penetrated the gram (-) outer bacterial membrane, and subsequent activation with 660 nm laser light rapidly killed escherichia coli infecting exci ... | 2002 | 11837327 |
| the ner gene of photorhabdus: effects on primary-form-specific phenotypes and outer membrane protein composition. | the nematode-bacterium complex of heterorhabditis-photorhabdus is pathogenic to insect larvae. the bacteria undergo a form of phenotypic switching whereby the primary form, at the stationary phase of the growth cycle, makes a range of products and has the capacity to support nematode growth, whereas the secondary form does not express these phenotypes. the work described here investigated the mechanism regulating phenotypic variation by transforming the primary cells with secondary-form dna on a ... | 2002 | 12003952 |
| an escherichia coli biosensor strain for amplified and high throughput detection of antimicrobial agents. | we report here the construction of a bacterial reporter system for high-throughput screening of antimicrobial agents. the test organism is the escherichia coli k-12 strain carrying luciferase genes luxc, luxd, luxa, luxb, and luxe from the bioluminescent bacterium photorhabdus luminescens in a runaway replication plasmid. the replication of the plasmid can be induced, resulting in a change of the plasmid copy number from 1-2/cell to several hundreds per cell within tens of minutes. this increase ... | 2002 | 12006110 |
| a luminescent escherichia coli biosensor for the high throughput detection of beta-lactams. | a group-specific bioluminescent escherichia coli strain for studying the action of beta-lactam antibiotics is described. the strain contains a plasmid, pblalux1, in which the luciferase genes from photorhabdus luminescens are inserted under the control of the beta-lactam-responsive element ampr/ampc from citrobacter freundii. in the presence of beta-lactams, the bacterial cells are induced to express the luciferase enzyme and three additional enzymes generating the substrate for the luciferase r ... | 2002 | 12006111 |
| bacterial infection of a model insect: photorhabdus luminescens and manduca sexta. | invertebrates, including insects, are being developed as model systems for the study of bacterial virulence. however, we understand little of the interaction between bacteria and specific invertebrate tissues or the immune system. to establish an infection model for photorhabdus, which is released directly into the insect blood system by its nematode symbiont, we document the number and location of recoverable bacteria found during infection of manduca sexta. after injection into the insect larv ... | 2002 | 12067318 |
| the phla hemolysin from the entomopathogenic bacterium photorhabdus luminescens belongs to the two-partner secretion family of hemolysins. | photorhabdus is an entomopathogenic bacterium symbiotically associated with nematodes of the family heterorhabditidae. bacterial hemolysins found in numerous pathogenic bacteria are often virulence factors. we describe here the nucleotide sequence and the molecular characterization of the photorhabdus luminescens phlba operon, a locus encoding a hemolysin which shows similarities to the serratia type of hemolysins. it belongs to the two-partner secretion (tps) family of proteins. in low-iron con ... | 2002 | 12081958 |
| identification and sequence of an unstable dna element in the entomopathogenic bacteria photorhabdus temperata strain k122. | a search was conducted for a difference in genome composition between phenotypic variants of the insect pathogenic bacteria, photorhabdus temperata. | 2002 | 12100588 |
| diverse bacteria are pathogens of caenorhabditis elegans. | practically and ethically attractive as model systems, invertebrate organisms are increasingly recognized as relevant for the study of bacterial pathogenesis. we show here that the nematode caenorhabditis elegans is susceptible to a surprisingly broad range of bacteria and may constitute a useful model for the study of both pathogens and symbionts. | 2002 | 12117988 |
| a single photorhabdus gene, makes caterpillars floppy (mcf), allows escherichia coli to persist within and kill insects. | photorhabdus luminescens, a bacterium with alternate pathogenic and symbiotic phases of its lifestyle, represents a source of novel genes associated with both virulence and symbiosis. this entomopathogen lives in a "symbiosis of pathogens" with nematodes that invade insects. thus the bacteria are symbiotic with entomopathogenic nematodes but become pathogenic on release from the nematode into the insect blood system. within the insect, the bacteria need to both avoid the peptide- and cellular- ( ... | 2002 | 12136122 |
| identification, characterization, and regulation of a cluster of genes involved in carbapenem biosynthesis in photorhabdus luminescens. | the luminescent entomopathogenic bacterium photorhabdus luminescens produces several yet-uncharacterized broad-spectrum antibiotics. we report the identification and characterization of a cluster of eight genes (named cpma to cpmh) responsible for the production of a carbapenem-like antibiotic in strain tt01 of p. luminescens. the cpm cluster differs in several crucial aspects from other car operons. the level of cpm mrna peaks during exponential phase and is regulated by a rap/hor homolog ident ... | 2002 | 12147472 |
| detection of traces of tetracyclines from fish with a bioluminescent sensor strain incorporating bacterial luciferase reporter genes. | bioluminescent escherichia coli k-12 strain for the specific detection of the tetracycline family of antimicrobial agents was optimized to work with fish samples. the biosensing strain contains a plasmid incorporating the bacterial luciferase operon of photorhabdus luminescens under the control of the tetracycline responsive element from transposon tn10 (korpela et al. anal. chem. 1998, 70, 4457-4462). the extraction procedure of oxytetracycline from rainbow trout (oncorhynchus mykiss) tissue wa ... | 2002 | 12166964 |
| a zinc metalloprotease inhibitor, inh, from the insect pathogen photorhabdus luminescens. | the entomopathogen photorhabdus luminescens secretes many proteins during the late stages of insect larvae infection and during in vitro laboratory culture. the authors have previously characterized and purified a 55 kda zinc metalloprotease, prta, from culture supernatants of p. luminescens. prta is secreted via a classical type i secretory pathway and is encoded within the operon prta-inh-prtbcd. the 405 bp inh gene encodes a 14.8 kda pre-protein that is translocated to the periplasm by the cl ... | 2002 | 12177336 |
| generation of thermostable monomeric luciferases from photorhabdus luminescens. | bacterial luciferases and the genes encoding these light-emitting enzymes have an increasing number of applications in biological sciences. temperature lability and the heterodimeric nature of these luciferases have been the major obstacles for their widespread use, for instance, as genetic reporters. escherichia coli expressing wild-type photorhabdus luminescens luciferase was found to produce eight times more light than the corresponding vibrio harveyi luciferase clone in vivo at 37 degrees c. ... | 2002 | 12207882 |
| differences between the pathogenic processes induced by steinernema and heterorhabditis (nemata: rhabditida) in pseudaletia unipuncta (insecta: lepidoptera). | larvae of pseudaletia unipuncta are moderately susceptible to infections caused by entomopathogenic nematodes, being a desirable host to study pathogenic processes caused by heterorhabditis bacteriophora, steinernema carpocapsae, and steinernema glaseri and their associated bacteria. the ability of the infective stage of these nematodes to invade hosts is quite different. s. carpocapsae invades the highest number of insects and presents the highest penetration rate, followed by h. bacteriophora. ... | 2002 | 12234542 |
| the lumicins: novel bacteriocins from photorhabdus luminescens with similarity to the uropathogenic-specific protein (usp) from uropathogenic escherichia coli. | bacteriocins are proteins produced by bacteria to destroy other bacteria occupying their ecological niche. photorhabdus luminescens is an insect pathogenic bacterium carried by an entomopathogenic nematode and occupies several different niches in its life cycle. the nematode enters the insect and releases a single strain of p. luminescens. the bacteria then kill the host and the bacteria and nematodes replicate within the cadaver. strikingly, at the end of the infection the cadaver is still occu ... | 2002 | 12351238 |
| role of hsp70 (dnak-dnaj-grpe) and hsp100 (clpa and clpb) chaperones in refolding and increased thermal stability of bacterial luciferases in escherichia coli cells. | the role of chaperones hsp70 (dnak-dnaj-grpe) and hsp100 (clpa-clpb-clpx) in refolding of thermoinactivated luciferase from the marine bacterium photobacterium fischeri and the terrestrial bacterium photorhabdus luminescens has been studied. these luciferases are homologous, but differ greatly in the rate of thermal inactivation and the rate constant for the luminescence reaction. it was shown that refolding of thermoinactivated luciferases is completely determined by the dnak-dnaj-grpe system. ... | 2002 | 12387711 |