| the xnp1 p2-like tail synthesis gene cluster encodes xenorhabdicin and is required for interspecies competition. | xenorhabdus nematophila, the mutualistic bacterium of the nematode steinernema carpocapsae, produces the r-type bacteriocin called xenorhabdicin that is thought to confer a competitive advantage for growth in the insect host. we have identified a p2-like tail synthesis gene cluster (xnp1) that was required for xenorhabdicin production. the xnp1 genes were expressed constitutively during growth and were induced by mitomycin c. deletion of either the sheath (xnps1) or fiber (xnph1) genes eliminate ... | 2011 | 21602326 |
| enzymatic characterization of a serralysin-like metalloprotease from the entomopathogen bacterium, xenorhabdus. | we investigated the enzymatic properties of a serralysin-type metalloenzyme, provisionally named as protease b, which is secreted by xenorhabdus bacterium, and probably is the ortholog of pra peptidase of photorhabdus bacterium. testing the activity on twenty-two oligopeptide substrates we found that protease b requires at least three amino acids n-terminal to the scissile bond for detectable hydrolysis. on such substrate protease b was clearly specific for positively charged residues (arg and l ... | 2011 | 21635975 |
| manipulation of ph shift to enhance the growth and antibiotic activity of xenorhabdus nematophila. | to evaluate the effects of ph control strategy on cell growth and the production of antibiotic (cyclo(2-me-baba-gly)) by xenorhabdus nematophila and enhance the antibiotic activity. the effects of uncontrolled- (different initial ph) and controlled-ph (different constant ph and ph-shift) operations on cell growth and antibiotic activity of x. nematophila yl00i were examined. experiments showed that the optimal initial ph for cell growth and antibiotic production of x. nematophila yl001 occurred ... | 2011 | 21660139 |
| host-pathogen interactions: proline gives insect pathogens the green light. | how does a quiescent symbiont of a nematode worm know when to turn nasty? metabolic analysis and genetic knockouts confirm that model insect pathogens can sense l-proline in insect blood. this not only serves as a wake-up call, activating secondary metabolite virulence factors, but also provides an energy source for a metabolic shift appropriate for adaptation to the host environment. | 2010 | 20152135 |
| influence of cell density and phase variants of bacterial symbionts (xenorhabdus spp.) on dauer juvenile recovery and development of biocontrol nematodes steinernema carpocapsae and s. feltiae (nematoda: rhabditida). | the rhabditid nematodes steinernema carpocapsae and steinernema feltiae are used in biological control of insect pests. mass production is done in liquid culture media pre-incubated with their bacterial symbionts xenorhabdus nematophila and xenorhabdus bovienii, respectively, before nematode dauer juveniles (djs) are inoculated. as a response to food signals produced by the bacterial symbionts, the djs exit from the developmentally arrested dauer stage (they recover development) and grow to adul ... | 2009 | 19319521 |
| comparative in vivo gene expression of the closely related bacteria photorhabdus temperata and xenorhabdus koppenhoeferi upon infection of the same insect host, rhizotrogus majalis. | photorhabdus and xenorhabdus are gram-negative, phylogenetically related, enterobacteria, forming mutualism with the entomopathogenic nematodes heterorhabditis and steinernema, respectively. the mutualistic bacteria living in the intestines of the nematode infective juveniles are pathogenic to the insect upon release by the nematodes into the insect hemolymph. such a switch needs activation of genes that promote bacterial virulence. we studied in vivo gene expression in photorhabdus temperata an ... | 2009 | 19754939 |
| beyond bacteria: a study of the enteric microbial consortium in extremely low birth weight infants. | extremely low birth weight (elbw) infants have high morbidity and mortality, frequently due to invasive infections from bacteria, fungi, and viruses. the microbial communities present in the gastrointestinal tracts of preterm infants may serve as a reservoir for invasive organisms and remain poorly characterized. we used deep pyrosequencing to examine the gut-associated microbiome of 11 elbw infants in the first postnatal month, with a first time determination of the eukaryote microbiota such as ... | 2011 | 22174751 |
| the entomopathogenic bacterial endosymbionts xenorhabdus and photorhabdus: convergent lifestyles from divergent genomes. | members of the genus xenorhabdus are entomopathogenic bacteria that associate with nematodes. the nematode-bacteria pair infects and kills insects, with both partners contributing to insect pathogenesis and the bacteria providing nutrition to the nematode from available insect-derived nutrients. the nematode provides the bacteria with protection from predators, access to nutrients, and a mechanism of dispersal. members of the bacterial genus photorhabdus also associate with nematodes to kill ins ... | 2011 | 22125637 |
| Phenotypic variation and host interactions of Xenorhabdus bovienii SS-2004, the entomopathogenic symbiont of Steinernema jollieti nematodes. | Xenorhabdus bovienii (SS-2004) bacteria reside in the intestine of the infective-juvenile (IJ) stage of the entomopathogenic nematode, Steinernema jollieti. The recent sequencing of the X. bovienii genome facilitates its use as a model to understand host - symbiont interactions. To provide a biological foundation for such studies, we characterized X. bovienii in vitro and host interaction phenotypes. Within the nematode host X. bovienii was contained within a membrane bound envelope that also en ... | 2011 | 22151385 |
| role of mrx fimbriae of xenorhabdus nematophila in competitive colonization of the nematode host. | xenorhabdus nematophila engages in mutualistic associations with the infective juvenile (ij) stage of specific entomopathogenic nematodes. mannose-resistant (mrx) chaperone-usher-type fimbriae are produced when the bacteria are grown on nutrient broth agar (nb agar). the role of mrx fimbriae in the colonization of the nematode host has remained unresolved. we show that x. nematophila grown on lb agar produced flagella rather than fimbriae. ijs propagated on x. nematophila grown on lb agar were c ... | 2011 | 21856828 |
| improvement of antibiotic activity of xenorhabdus bovienii by medium optimization using response surface methodology. | abstract: | 2011 | 22082189 |
| szentiamide, an n-formylated cyclic depsipeptide from xenorhabdus szentirmaii dsm 16338t. | szentiamide (1) a new cyclic hexadepsipeptide was isolated from the culture broth of the entomopathogenic bacterium xenorhabdus szentirmaii dsm 16338t. the structure was elucidated by analysis of one- and two-dimensional nmr spectra and high resolution mass spectrometry. the amino acids were determined to be d-leucine, l-threonine, d-phenylalanine, d-valine, l-tyrosine and l-tryptophane after hydrolysis and derivatization with d-fdva [nalpha-(2,4-dinitro-5-fluorophenyl)-d-valinamide]. | 2011 | 21941889 |
| cell lines, md108 and md66, from the hemocytes of malacosoma disstria (lepidoptera) display aspects of plasma-free innate non-self activities. | the innate non-self response systems of the deciduous tree pest, the forest tent caterpillar, malacosoma disstria has been documented by us in terms of in vitro and in vivo reactions towards the gram-positive nonpathogenic bacterium, bacillus subtilis and gram-negative pathogenic microbe, xenorhabdus nematophila and their respective surface antigens, lipopoteichoic acids (lta) and lipopolysaccharides (lps). these studies, often conducted in whole and diluted hemolymph, preclude examination of pl ... | 2011 | 21907208 |
| 3d structure of the yersinia entomophaga toxin complex and implications for insecticidal activity. | toxin complex (tc) proteins are a class of bacterial protein toxins that form large, multisubunit complexes. comprising tca, b, and c components, they are of great interest because many exhibit potent insecticidal activity. here we report the structure of a novel tc, yen-tc, isolated from the bacterium yersinia entomophaga mh96, which differs from the majority of bacterially derived tcs in that it exhibits oral activity toward a broad range of insect pests, including the diamondback moth (plutel ... | 2011 | 22158901 |
| Transient expression of a viral histone H4 inhibits expression of cellular and humoral immune-associated genes in Tribolium castaneum. | A viral histone H4 is encoded in a polydnavirus called Cotesia plutellae bracovirus (CpBV), which is symbiotic to an endoparasitoid wasp, C. plutellae. Compared to general histone H4s, the viral H4 possesses an extra N-terminal tail containing 38 amino acid residues, which has been presumed to control host gene expression in an epigenetic mode. To analyze the epigenetic control activity of CpBV-H4 on expression of immune-associated genes, it was transiently expressed in larvae of Tribolium casta ... | 2011 | 22037579 |
| structural analysis of chi1 chitinase from yen-tc: the multisubunit insecticidal abc toxin complex of yersinia entomophaga. | yersinia entomophaga mh96 is a native new zealand soil bacterium that secretes a large abc-type protein toxin complex, yen-tc, similar to those produced by nematode-associated bacteria such as photorhabdus luminescens. y. entomophaga displays an exceptionally virulent pathogenic phenotype in sensitive insect species, causing death within 72 h of infection. because of this phenotype, there is intrinsic interest in the mechanism of action of yen-tc, and it also has the potential to function as a n ... | 2011 | 22108167 |
| Purification, molecular characterization and gene expression analysis of an aspartic protease (Sc-ASP113) from the nematode Steinernema carpocapsae during the parasitic stage. | Steinernema carpocapsae is an insect parasitic nematode associated with the bacterium Xenorhabdus nematophila. During invasion, this nematode is able to express many proteases, including aspartic proteases. Genes encoding these aspartic proteases have been identified in the EST, and aspartic protease has been found in excretory-secretory products. The total protease was shown to digest blood hemoglobin in a zymogram gel. When the protein was partially purified by pepstatin affinity chromatograph ... | 2011 | 22178695 |
| NRPS substrate promiscuity diversifies the xenematides. | Xenematide, a cyclic depsipeptide antibiotic produced by Xenorhabdus nematophila, had a candidate nonribosomal peptide synthetase (NRPS) with atypical features. Differential metabolite analysis between a mutant and wildtype validated that this stand-alone NRPS was required for xenematide production, and further analysis led to a series of new xenematide derivatives encoded by the same NRPS. Our results indicate that adenylation domain promiscuity and relaxed downstream processing in the X. nemat ... | 2011 | 21888371 |
| a natural prodrug activation mechanism in nonribosomal peptide synthesis. | we have identified a new mechanism for the cleavage and activation of nonribosomally made peptides and peptide-polyketide hybrids that are apparently operational in several different bacteria. this process includes the cleavage of a precursor molecule by a membrane-bound and d-asparagine-specific peptidase, as shown here in the biosynthesis of the antibiotic xenocoumacin from xenorhabdus nematophila. | 2011 | 21926994 |
| Description of Xenorhabdus magdalenensis sp. nov., the symbiotic bacterium associated with Steinernema australe. | The symbiotic bacterium (IMI 397775T, DSM 24915T) was isolated from the insect-pathogenic nematode Steinernema australe. On the basis of 16S rRNA gene sequence similarity, this bacterial isolate was shown to belong to the genus Xenorhabdus in agreement with the genus of its nematode-host. The accurate phylogenetic position of this new isolate was defined using a multigene approach and showed that isolate IMI 397775T shares a common ancestor with X. doucetiae FRM16 T and X. romanii PR06-AT, the s ... | 2011 | 21948091 |
| Detection and Identification of Species-Specific Bacteria Associated with Synanthropic Mites. | Internal bacterial communities of synanthropic mites Acarus siro, Dermatophagoides farinae, Lepidoglyphus destructor, and Tyrophagus putrescentiae (Acari: Astigmata) were analyzed by culturing and culture-independent approaches from specimens obtained from laboratory colonies. Homogenates of surface-sterilized mites were used for cultivation on non-selective agar and DNA extraction. Isolated bacteria were identified by sequencing of the 16S rRNA gene. PCR amplified 16S rRNA genes were analyzed b ... | 2011 | 22057398 |
| determination of the absolute configuration of peptide natural products by using stable isotope labeling and mass spectrometry. | structure elucidation of natural products including the absolute configuration is a complex task that involves different analytical methods like mass spectrometry, nmr spectroscopy, and chemical derivation, which are usually performed after the isolation of the compound of interest. here, a combination of stable isotope labeling of photorhabdus and xenorhabdus strains and their transaminase mutants followed by detailed ms analysis enabled the structure elucidation of novel cyclopeptides named ga ... | 2012 | 22266804 |
| assessing computational tools for the discovery of small rna genes in bacteria. | over the past decade, a number of biocomputational tools have been developed to predict small rna (srna) genes in bacterial genomes. in this study, several of the leading biocomputational tools, which use different methodologies, were investigated. the performance of the tools, both individually and in combination, was evaluated on ten sets of benchmark data, including data from a novel rna-seq experiment conducted in this study. the results of this study offer insight into the utility as well a ... | 2011 | 21768221 |
| 16s rdna-based phylogeny of non-symbiotic bacteria of entorno-pathogenic nematodes from infected insect cadavers. | using 16s rdna gene sequencing technique, three different species of non-symbiotic bacteria of entomopatho-genic nematodes (epns) (steinernema sp. and heterorhabditis sp.) were isolated and identified from infected insect cadavers {galleria mellonella larvae) after 48-hour post infections. sequence similarity analysis revealed that the strains srk3, srk4 and srk5 belong to ochrobactrum cytisi, schineria larvae and ochrobactrum anthropi, respectively. the isolates o. anthropi and s. larvae were f ... | 2011 | 21802047 |
| cytotoxic fatty acid amides from xenorhabdus. | | 2011 | 21751325 |