Isolation of Harveyi clade Vibrio spp. collected in aquaculture farms: How can the identification issue be addressed?

Antoine Culot (1, 2) , Noel Grosset (1) , Quentin Bruey (2) , Michel Auzou (3) , Jean-Christophe J.-C. Giard (3) , Baptiste Favard (2) , Alexandre Wakatsuki (4) , Sandrine Baron (5) , Stephane Frouel (2) , Clarisse Techer (2) , Michel Gautier (1)

1 STLO - Science et Technologie du Lait et de l'Oeuf
2 MIXscience
3 Service de Microbiologie [CHU Caen]
4 Zoopeixes Fish Company
5 Laboratoire de Ploufragan-Plouzané-Niort [ANSES]

Aquaculture is a fast growing industry with its development hampered by bacterial diseases. Vibriosis caused by Harveyi clade strains is known for causing heavy loss especially in shrimp aquaculture farms. For farm treatment and pathogen spread management, veterinarians and researchers need reliable bacterial identification tools. A range of identification methods have been presented for Vibrio spp. in recent literature but little feedback on their performance have been made available to this day. This study aims at comparing Vibrio spp. identification methods and providing guidance on their use. Fifty farms were sampled and bacterial colonies were isolated using specific culture media before microscopic analysis and genomic profiling using ERIC-PCR. A preliminary identification step was carried out using MALDIToF mass spectrometry. Four methods were compared for strain identification on 14 newly isolated Harveyi clade Vibrio spp. strains: whole genome sequencing (digital DNA DNA Hybridization (dDDH)), 5 MLSA schemes, ferric uptake regulation (fur) and lecithin-dependent haemolysin (ldh) single gene based identification methods. Apart from dDDH which is a reference method, no technique could identify all the isolates to the species level. The other tested techniques allowed a faster, cheaper but sub genus clade identification which can be interesting when absolute precision is not required. In this regard, MALDI-ToF and fur based identification seemed especially promising.

Mots clés: Vibrio harveyi; Aquaculture; Shrimp pathogen; Identification; Fur; Ldh; MLSA; MALDI-Tof

Domaines: Microbiologie et Parasitologie

Antoine Culot, Noel Grosset, Quentin Bruey, Michel Auzou, Jean-Christophe J.-C. Giard, et al.. Isolation of Harveyi clade Vibrio spp. collected in aquaculture farms: How can the identification issue be addressed?. Journal of Microbiological Methods, 2021, 180, pp.106106. ⟨10.1016/j.mimet.2020.106106⟩. ⟨hal-03099757⟩