Elodie Blanchet

Isolation of microsatellite markers in the Calliptamus genus (Orthoptera, Acrididae).

Abstract The Calliptamus genus (Orthoptera: Acrididae) includes locust and grasshopper species, some of which have a high economic impact. Using an enriched methodology, 10 microsatellite markers have been developed from two species, Calliptamus italicus and Calliptamus barbarus. These polymorphic markers were tested on different populations of three Calliptamus species: C. italicus, C. barbarus, C. wattenwylianus. Two markers were amplified on the three species, as well as four on C. barbarus and two on C. italicus. In each species, 9 to 23 alleles per locus were observed. These molecular markers might prove to be a new and interesting tool for Calliptamus population genetics and dispersion studies.

Characterization of N-Acyl Homoserine Lactones in Vibrio tasmaniensis LGP32 by a Biosensor-Based UHPLC-HRMS/MS Method

Since the discovery of quorum sensing (QS) in the 1970s, many studies have demonstrated that Vibrio species coordinate activities such as biofilm formation, virulence, pathogenesis, and bioluminescence, through a large group of molecules called N-acyl homoserine lactones (AHLs). However, despite the extensive knowledge on the involved molecules and the biological processes controlled by QS in a few selected Vibrio strains, less is known about the overall diversity of AHLs produced by a broader range of environmental strains. To investigate the prevalence of QS capability of Vibrio environmental strains we analyzed 87 Vibrio spp. strains from the Banyuls Bacterial Culture Collection (WDCM911) for their ability to produce AHLs. This screening was based on three biosensors, which cover a large spectrum of AHLs, and revealed that only 9% of the screened isolates produced AHLs in the defined experimental conditions. Among these AHL-producing strains, Vibrio tasmaniensis LGP32 is a well-known pathogen of bivalves. We further analyzed the diversity of AHLs produced by this strain using a sensitive bioguided UHPLC-HRMS/MS approach (Ultra-High-Performance Liquid Chromatography followed by High-Resolution tandem Mass Spectrometry) and we identified C10-HSL, OH-C12-HSL, oxo-C12-HSL and C14:1-HSL as QS molecules. This is the first report that documents the production of AHL by Vibrio tasmaniensis LGP32.

Quorum Sensing and Quorum Quenching in the Mediterranean Seagrass Posidonia oceanica Microbiota

Posidonia oceanica (L.) Delile is an endemic Mediterranean seagrass angiosperm. The taxonomic diversity of the Posidonia-associated microbiota has previously been inventoried using culture-based and culture-independent approaches. However, little is known about the type of chemical interactions that occur between the cells within this microbiota. In this study, we isolated 60 bacterial strains from the leaves and rhizomes of Posidonia oceanica and evaluated their capacity to communicate through quorum sensing. We found 6 strains able to emit 8 different types of quorum sensing acyl homoserine lactones, identified through UHPLC-HRMS/MS after bioguided fractionation of large cultures. We also identified 19 strains able to produce furanosyl diester borate, another type of quorum sensing autoinducer. Also, 5 strains were found to produce quorum quenching compounds. Finally, as quorum sensing is known to be involved in biofilm production, we also tested whether strains positive to our biotests were able to produce biofilms. Collectively, these data reveal the importance of examining chemical interactions within this bacterial consortium associated with Posidonia oceanica that could have an impact on the physiology of this key Mediterranean seagrass.