Survival behaviour and virulence of the fish pathogen Vibrio ordalii in seawater microcosms

Abstract

Vibrio ordalii, the causative agent of atypical vibriosis, is a Gram-negative, motile, rod-shaped bacterium that severely affects the salmonid aquaculture industry. V. ordalii has been biochemically, antigenically and genetically characterized. However, studies on the survival behaviour of this bacterium in aquatic environments are scarce, and there is no information regarding its disease transmission and infectious abilities outside of the fish host or regarding water as a possible reservoir. The present study investigated the survival behaviour of V. ordalii Vo-LM-06 and Vo-LM-18 in sterile and non-sterile seawater microcosms. After a year in sterile seawater without nutrients, 1% of both V. ordalii strains survived (~10 3 colony-forming units ml −1 ), and long-term maintenance did not affect bacterial biochemical or genetic properties. Additionally, V. ordalii maintained for 60 d in sterile seawater remained infective in rainbow trout Oncorhynchus mykiss. However, after 2 d of natural seawater exposure, this bacterium became nonculturable, indicating that autochthonous microbiota may play an important role in survival. Recuperation assays that added fresh medium to non-sterile microcosms did not favour V. ordalii recovery on solid media. Our results contribute towards a better understanding of V. ordalii survival behaviour in seawater ecosystems. KEY WORDS: Vibrio ordalii · Vibriosis · Survival · MicrocosmResale or republication not permitted without written consent of the publisher

Survival Characteristics and Transcriptomic Analyses Reveal the Adaptive Response of the Aquatic Pathogen Non-O1/O139 Vibrio cholerae to Starvation Stress

“…In this study, the survival and morphology of non-O1/O139 V. cholerae cells were investigated under starvation conditions, and the results showed that non-O1/O139 V. cholerae could survive a long time of 6 months with reduction in the size of cells, turning them from rods to approximately spherical, which was consistent with the long-term survival and morphological changes of other Vibrio spp. ( 15 , 16 ). It is clear that bacteria have evolved mechanisms to survive under starvation stress by reducing cell size and turning into a round cell shape ( 17 ).…”

The Fish Pathogen Vibrio ordalii Under Iron Deprivation Produces the Siderophore Piscibactin

“…Three V. ordalii strains were used: The type strain ATCC 33509 T and two strains, Vo-LM-13 and Vo-LM-18, previously isolated from vibriosis outbreaks in Atlantic salmon cultured in Chile [3,6]. All were confirmed as V. ordalii according to the PCR protocol previously described [30].…”

“…While its pathogenicity is not correlated to erythrocytes hemagglutination capacity or biofilm formation in Atlantic salmon ( Salmo salar ), the hydrophobic properties of V. ordalii cells could play a role in virulence. Moreover, V. ordalii can evade the host immune system and can survive within Atlantic salmon mucus, which likely facilitates colonization [3,6]. However, many aspects of its ability to colonize and multiply within the fish hosts remain unclear.…”