Articles

ENDOSYMBIONTS OF ENTOMOPATHOGENIC NEMATODES FROM SOUTH ITALY:A PHENOTYPIC STUDY


Abstract


We examined different Xenorhabdusstrains (five of X. bovieniiand two of X. kozodoii), obtained from EPNisolates belonging to the genus Steinernema(S. feltiae, S. ichnusae, S. apuliae, S. vulcanicum) of different geographicorigin by both genotypic and phenotypic analysis. Common laboratory assays were done for traits such as antibioticresistance, haemolytic activity, lactose utilisation, biofilm production, chosen as the least selectable traits for EPN life-cycle, and thus as (presumably) neutral traits. As selective marker, the activity of the endosymbiont’s toxins was verified inan in vivoassay on G. mellonellalarvae. Genotyping done by 16S partial sequencing was used for identification purposes.Xenorhabdusbovieniiisolates showed a broad phenotypic spectrum; on the other hand, X. kozodoiishowed a less degreeof phenotypic variation, reduced ability of biofilm production and conspicuous β-galactosidase activity. However, all thestrains were able to kill G. mellonellalarvae with high efficiency.

Keywords

symbiosis, Steinernema, Xenorhabdus, Italy

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