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Communication Dans Un Congrès Année : 2015

The pathobiote of the Steinernema entomopathogenic nematodes: the Xenorhabdus bacterial symbionts and the others …

Résumé

Entomopathogenic nematodes from the genus Steinernema are used in biological control of insect pests. The free form of the nematode (infective juveniles) is in closed symbiotic association with the intestinal bacteria Xenorhabdus (Enterobacteriaceae). In the well-studied Steinernema carpocapsae - Xenorhabdus nematophila couple, it was largely shown that the bacterial symbiont plays an important role in the death of the insect and in the elimination of the microbial competitors inside the insect cadaver (1). Recently, other Steinernema – Xenorhabdus couples with different pathologic features have been described. By contrast with X. nematophila, in these couples, the bacterial symbionts are non-virulent when directly injected in insects (2,3). Three non-exclusive hypotheses may explain these observations: 1.the complementarity of the virulence functions between nematodes and bacteria allows couples to succeed in the infection 2.an auxiliary microbiota carried by the infective juveniles participates to the infectious process in insect, 3.the indigenous microbiota associated with the healthy insects participates to the infectious process. Here, we present studies that explore the auxiliary bacterial microbiota of the nematodes (hypothesis 2). In this goal, we used molecular approaches (DGGE, barcoding). 2 to 5 dominant OTUs were identified depending on the Steinernema – Xenorhabdus couples. Most of them belong to the genera Providencia, Serratia, Sphingomonas, Brevundimonas, Stenotrophomonas, Ochrobactrum and Pseudomonas. We also found these OTUs in the lepidopteran insect, Spodoptera littoralis, after infestation with these Steinernema – Xenorhabdus couples. Interestingly, during the infectious process the Xenorhabdus symbiont is not systematically the main taxon in insect cadavers. Bacteriological isolation of some OTUs of this microbiota and evaluation of its phenotypic potential (insecticidal, antimicrobial activities) will allow the deciphering of the role of this microbiota in the whole infectious process.
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Dates et versions

hal-01837280 , version 1 (12-07-2018)

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  • HAL Id : hal-01837280 , version 1
  • PRODINRA : 309912

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Jean-Claude Ogier, Sylvie Pages, Maxime Galan, Alain Givaudan, Sophie Gaudriault. The pathobiote of the Steinernema entomopathogenic nematodes: the Xenorhabdus bacterial symbionts and the others …. Pathobiome 2015, Jun 2015, National Veterinary School (ENVA), Maisons-Alfort, France. ⟨hal-01837280⟩
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