Tenacibaculosis induction in the Senegalese sole (Solea senegalensis) and studies of Tenacibaculum maritimum survival against host mucus and plasma.

Abstract

Tenacibaculum maritimum, the aetiological agent for marine tenacibaculosis, is one of the most significant pathogens that threaten Senegalese sole, Solea senegalensis (Kaup), aquaculture. Because no immersion challenge with T.maritimum has been reported previously for this flatfish species, this study aimed to optimize bacterial yields as well as to establish a challenge model for tenacibaculosis induction. Several approaches were performed to optimize bacterial culture conditions, including treatment with non-ionic surfactants, detergents, cellulase hydrolysis and strong shaking. A prolonged bath challenge was performed for 24h under two different temperatures, 16 and 23°C. Moreover, mucus and plasma bactericidal activities against T.maritimum were also assessed. Culturing bacteria with strong shaking and continuous shaking provided suitable culture conditions to obtain higher bacterial yields without aggregation and fluctuation, contrary to most other treatments that showed a huge amount of bacterial aggregates. A prolonged bath method for 24h, without skin or gill scarification, was considered suitable for disease induction with high mortality rates. Moreover, data regarding mucus and plasma bactericidal activities suggested that there is a lack of host innate immune response against T.maritimum orthat this particular pathogen presents evading strategies against Senegalese sole.