Characterization of the Entomopathogenic Bacterium Photorhadus Luminescens Sonorensis, and Bioactivity of its Secondary Metabolites
AuthorOrozco, Rousel Antonio
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PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
EmbargoRelease after 22-May-2013
AbstractPhotorhabdus are motile Gram-negative bacteria that have a mutualistic association with entomopathogenic Heterorhabditis nematodes. Nematodes vector the bacteria from one insect host to another, while the bacterial symbiont produces toxins and secondary metabolites that kill that the insect host. In this study, we characterize the bacterial symbiont of Heterorhabditis sonorensis, recently discovered in the Sonoran desert. Biochemical and molecular methods including sequence data from five genes: 16s rDNA, gyrB, recA, gltX, dnaN were considered. Evolutionary relationships of this new Photorhabdus subsp. were inferred considering maximum parsimony and Bayesian analyses. We also surveyed for secondary metabolites (SM) produced by this microorganism, considering HPLC and mass spectrometry analyses. SM crude extracts showed activity against the corn ear worm Helicoverpa zea, the root-knot nematode (Meloidogyne incognita), the bacterium Pseudomonas syringae, and the fungus Fusarium oxysporum; and were more toxic that those produced by related species. Results from these studies showed that Photorhabdus l. sonorensis' secondary metabolites have potent antagonistic activity against these plant pathogens.
Degree ProgramGraduate College