Show simple item record

dc.contributor.authorEasom, Catherine A
dc.contributor.authorJoyce, Susan A
dc.contributor.authorClarke, David J
dc.date.accessioned2010-03-08T13:11:06Z
dc.date.available2010-03-08T13:11:06Z
dc.date.issued2010
dc.identifier.citationIdentification of genes involved in the mutualistic colonization of the nematode Heterorhabditis bacteriophora by the bacterium Photorhabdus luminescens. 2010, 10:45 BMC Microbiol.en
dc.identifier.issn1471-2180
dc.identifier.pmid20149243
dc.identifier.doi10.1186/1471-2180-10-45
dc.identifier.urihttp://hdl.handle.net/10147/93824
dc.description.abstractABSTRACT: BACKGROUND: Photorhabdus are Gram negative entomopathogenic bacteria that also have a mutualistic association with nematodes from the family Heterorhabditis. An essential part of this symbiosis is the ability of the bacterium to colonize the gut of the freeliving form of the nematode called the infective juvenile (IJ). Although the colonization process (also called transmission) has been described phenomonologically very little is known about the underlying molecular mechanisms. Therefore, in this study, we were interested in identifying genes in Photorhabdus that are important for IJ colonization. RESULTS: In this work we genetically tagged P. luminescens TT01 with gfp and constructed a library containing over 3200 mutants using the suicide vector, pUT-Km2. Using a combination of in vitro symbiosis assays and fluorescent microscopy we screened this library for mutants that were affected in their ability to colonize the IJ i.e. with decreased transmission frequencies. In total 8 mutants were identified with transmission frequencies of
dc.language.isoenen
dc.titleIdentification of genes involved in the mutualistic colonization of the nematode Heterorhabditis bacteriophora by the bacterium Photorhabdus luminescens.en
dc.contributor.departmentDepartment of Microbiology, University College Cork, Ireland. david.clarke@ucc.ie.en
dc.identifier.journalBMC microbiologyen
refterms.dateFOA2018-09-03T10:14:21Z
html.description.abstractABSTRACT: BACKGROUND: Photorhabdus are Gram negative entomopathogenic bacteria that also have a mutualistic association with nematodes from the family Heterorhabditis. An essential part of this symbiosis is the ability of the bacterium to colonize the gut of the freeliving form of the nematode called the infective juvenile (IJ). Although the colonization process (also called transmission) has been described phenomonologically very little is known about the underlying molecular mechanisms. Therefore, in this study, we were interested in identifying genes in Photorhabdus that are important for IJ colonization. RESULTS: In this work we genetically tagged P. luminescens TT01 with gfp and constructed a library containing over 3200 mutants using the suicide vector, pUT-Km2. Using a combination of in vitro symbiosis assays and fluorescent microscopy we screened this library for mutants that were affected in their ability to colonize the IJ i.e. with decreased transmission frequencies. In total 8 mutants were identified with transmission frequencies of </= 30% compared to wild-type. These mutants were mapped to 6 different genetic loci; the pbgPE operon, galE, galU, proQ, asmA and hdfR. The pbgPE, galE and galU mutants were all predicted to be involved in LPS biosynthesis and, in support of this, we have shown that these mutants are avirulent and sensitive to the cationic antimicriobial peptide, polymyxin B. On the other hand the proQ, asmA and hdfR mutants were not affected in virulence and were either as resistant (proQ) or slightly more sensitive (asmA, hdfR) to polymyxin B than the wild-type (WT). CONCLUSIONS: This is the first report describing the outcome of a comprehensive screen looking for transmission mutants in Photorhabdus. In total 6 genetic loci were identified and we present evidence that all of these loci are involved in the assembly and/or maintenance of LPS and other factors associated with the cell surface. Interestingly several, but not all, of the transmission mutants identified were also avirulent suggesting that there is a significant, but not complete, genetic overlap between pathogenicity and mutualism. Therefore, this study highlights the importance of the cell surface in mediating the symbiotic and pathogenic interactions of Photorhabdus.


Files in this item

Thumbnail
Name:
20149243x.pdf
Size:
604.5Kb
Format:
PDF

This item appears in the following Collection(s)

Show simple item record