Entomopathogenic nematodes of the genera Steinernema and Heterorhabditis, along with their bacterial symbionts from the genera Xenorhabdus and Photorhabdus, respectively, are important biological control agents against agricultural pests. Rapid progress in the development of genomic tools has catalyzed a transformation of the systematics of these organisms, reshaping our understanding of their phylogenetic and cophlylogenetic relationships. In this review, we discuss the major historical events in the taxonomy and systematics of this group of organisms, highlighting the latest advancements in these fields. Additionally, we synthesize information on nematode-bacteria associations and assess the existing evidence regarding their cophylogenetic relationships.

• Klíčová slova
• Beneficial microorganisms, Biological control agents, Entomopathogens, Phylogeny, Systematics, Taxonomy,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Several bacterial species from the Burkholderia cepacia complex (Bcc) are feared opportunistic pathogens that lead to debilitating lung infections with a high risk of developing fatal septicemia in cystic fibrosis (CF) patients. However, the pathogenic potential of other Bcc species is yet unknown. To elucidate clinical relevance of Burkholderia contaminans, a species frequently isolated from CF respiratory samples in Ibero-American countries, we aimed to identify its key virulence factors possibly linked with an unfavorable clinical outcome. We performed a genome-wide comparative analysis of two isolates of B. contaminans ST872 from sputum and blood culture of a female CF patient in Argentina. RNA-seq data showed significant changes in expression for quorum sensing-regulated virulence factors and motility and chemotaxis. Furthermore, we detected expression changes in a recently described low-oxygen-activated (lxa) locus which encodes stress-related proteins, and for two clusters responsible for the biosynthesis of antifungal and hemolytic compounds pyrrolnitrin and occidiofungin. Based on phenotypic assays that confirmed changes in motility and in proteolytic, hemolytic and antifungal activities, we were able to distinguish two phenotypes of B. contaminans that coexisted in the host and entered her bloodstream. Whole genome sequencing revealed that the sputum and bloodstream isolates (each representing a distinct phenotype) differed by over 1,400 mutations as a result of a mismatch repair-deficient hypermutable state of the sputum isolate. The inferred lack of purifying selection against nonsynonymous mutations and the high rate of pseudogenization in the derived isolate indicated limited evolutionary pressure during evolution in the nutrient-rich, stable CF sputum environment. The present study is the first to examine the genomic and transcriptomic differences between longitudinal isolates of B. contaminans. Detected activity of a number of putative virulence factors implies a genuine pathogenic nature of this novel Bcc species.

• MeSH
• bakteriální proteiny genetika   MeSH
• Burkholderia genetika   izolace a purifikace   patogenita   MeSH
• cystická fibróza komplikace   mikrobiologie   MeSH
• dítě MeSH
• faktory virulence genetika   metabolismus   fyziologie   MeSH
• genom bakteriální MeSH
• infekce bakteriemi rodu Burkholderia komplikace   MeSH
• lidé MeSH
• objevující se infekční nemoci MeSH
• oportunní infekce komplikace   mikrobiologie   MeSH
• quorum sensing MeSH
• regulace genové exprese u bakterií MeSH
• stanovení celkové genové exprese MeSH
• virulence genetika   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bakteriální proteiny MeSH
• faktory virulence MeSH

Burkholderia contaminans belongs to the Burkholderia cepacia complex (BCC), a group of bacteria that are ubiquitous in the environment and capable of infecting the immunocompromised and people with cystic fibrosis. We report here draft genome sequences for the B. contaminans type strain LMG 23361 and an Argentinian cystic fibrosis sputum isolate.

• Publikační typ
• časopisecké články MeSH

We examined if multilocus sequence typing (MLST), a method for genotyping and species identification of Burkholderia cepacia complex bacteria, could be applied directly to cystic fibrosis sputum. The redesigned nested-PCR MLST format was successfully used to accurately identify strains in 23 sputum samples, of which 8 were culture negative.

• MeSH
• bakteriální pneumonie mikrobiologie   MeSH
• Burkholderia cepacia komplex klasifikace   genetika   MeSH
• cystická fibróza komplikace   MeSH
• DNA bakterií chemie   genetika   MeSH
• genotyp MeSH
• infekce bakteriemi rodu Burkholderia mikrobiologie   MeSH
• lidé MeSH
• sekvenční analýza DNA MeSH
• shluková analýza MeSH
• sputum mikrobiologie   MeSH
• techniky typizace bakterií metody   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA bakterií MeSH

Burkholderia cenocepacia can cause serious infections and epidemics in patients with cystic fibrosis (CF). A CF population in the Czech Republic experienced an epidemic outbreak caused by a B. cenocepacia ST-32 strain. The clonality of the isolates was evident by multilocus sequence typing; however, fingerprinting profiles obtained by pulsed-field gel electrophoresis (PFGE) showed substantial band variability. We investigated whether the PFGE pattern diversity resulted from genomic rearrangements mediated by insertion sequences (IS); in addition, we determined whether stressful growth conditions altered the transposition activity of these IS. DNA probes for IS commonly found in B. cenocepacia were designed using the B. cenocepacia J2315 genome. Southern hybridization analysis of ST-32 isolates demonstrated diversity in both the copy number and the insertion site for a homologue of ISBcen20. Movement of the ISBcen20 homologue was detected when the ST-32 isolate CZ1238 was exposed to oxidative stress (growth in the presence of H(2)O(2)). PFGE analysis of CZ1238 derivatives exposed to oxidative stress demonstrated genomic rearrangements. Interestingly, when the closely related B. cenocepacia strain J2315 was exposed to oxidative stress, no movement of ISBcen20 was detected. Since frameshift mutations are present within the transposases of all copies of this IS in J2315, our data suggest that the transposase is inactive. In summary, we have demonstrated for the first time that IS movement can be mediated by oxidative stress and can lead to genomic rearrangements in the CF pathogen B. cenocepacia. These IS movements may alter the PFGE fingerprints of isolates that are clonal by other typing methods.

• MeSH
• Burkholderia klasifikace   genetika   izolace a purifikace   MeSH
• cystická fibróza komplikace   MeSH
• DNA bakterií genetika   MeSH
• DNA fingerprinting metody   MeSH
• epidemický výskyt choroby MeSH
• genetická variace * MeSH
• genotyp MeSH
• infekce bakteriemi rodu Burkholderia epidemiologie   mikrobiologie   MeSH
• lidé MeSH
• molekulární epidemiologie metody   MeSH
• oxidační stres * MeSH
• pulzní gelová elektroforéza metody   MeSH
• rekombinace genetická * MeSH
• shluková analýza MeSH
• techniky typizace bakterií metody   MeSH
• transpozibilní elementy DNA MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika epidemiologie   MeSH
• Názvy látek
• DNA bakterií MeSH
• transpozibilní elementy DNA MeSH