Adhesion to sole, Solea senegalensis Kaup, mucus of microorganisms isolated from farmed fish, and their interaction with Photobacterium damselae subsp. piscicida

Abstract

Most studies carried out to select microorganisms as candidate probiotics have focused on in vitro antagonism tests, such as the production of inhibitory compounds against pathogenic microorganisms. However, attachment to mucous surfaces could be another criterion to be considered when selecting potential probiotics for aquaculture. Nineteen isolates obtained from farmed Senegalese sole, Solea senegalensis Kaup, and gilthead sea bream, Sparus aurata L., have been evaluated for their capacity to adhere to skin and intestinal mucus of Senegalese sole, and their antagonistic effect against Photobacterium damselae subsp. piscicida, an important pathogen for farmed sole. The isolates from gilthead sea bream showed the highest percentage of adhesion to sole mucus, whilst the pathogenic microorganisms assayed and the isolates from sole showed, in general, a lower ability to adhere to sole mucus. The results suggest that the adhesion to fish mucus was more dependent on the isolate tested than on the host mucus. The isolates from gilthead sea bream also showed a higher antagonistic activity against P. damselae subsp. piscicida than those from Senegalese sole. Four isolates were selected, on the basis of their adhesive ability and antagonistic effect on P. damselae subsp. piscicida, to study their interactions with the pathogen in respect of adhesion to skin and intestinal mucus under exclusion, competition and displacement conditions. The results obtained show the ability of three isolates to reduce the adhesion of P. damselae subsp. piscicida to sole mucus under displacement and competition conditions. The adhesion of the pathogen to sole intestinal mucus was also significantly reduced when three isolates were assayed under exclusion conditions.

Adhesion to brown trout skin mucus, antagonism against cyst adhesion and pathogenicity to rainbow trout of some inhibitory bacteria against Saprolegnia parasitica

“…This suggests that the adhesion of bacteria to mucus has no host specificity and depends more on the bacterial isolate than on the kind of mucus tested. The lack of host specificity was also observed by other authors (Nikoskelainen et al 2001, Rinkinen et al 2003, Chabrillón et al 2005, 2006, although it would be a desirable characteristic in any bacteria to be used in biological control (Rinkinen et al 2003, Chabrillón et al 2005.…”

“…The adhesion of bacteria to the skin mucus of fish is a desirable characteristic if they are to be used in biological control of a disease (Chabrillón et al 2005). In the present study, the adhesion to the skin mucus of brown trout of the bacteria tested was low, with percentages of adhesion not higher than 15.3%.…”

“…In the present study, the adhesion to the skin mucus of brown trout of the bacteria tested was low, with percentages of adhesion not higher than 15.3%. The most adhesive isolate was Pseudomonas fluorescens LE 141, followed by Pantoea (Chabrillón et al 2005, 2006, Balcázar et al 2007, with adhesion being lower on skin mucus than on gut mucus of rainbow trout and other fish species on some occasions (Chabrillón et al 2006, Balcázar et al 2007. We observed that there was greater adhesion of bacteria to the skin mucus of male than of female brown trout, and this may have implications for the future treatment of fish with inhibitory bacteria against Saprolegnia parasitica.…”

“…infections are produced mainly via the skin; therefore, the skin mucus is the first barrier that S. parasitica must overcome if the skin is not cut or abraded. The ability of some potential probiotic bacteria to adhere to the skin and intestinal mucus of various fish species and to reduce the binding of some pathogens has previously been investigated (Nikoskelainen et al 2001, Vine et al 2004, Chabrillón et al 2005, 2006, Balcázar et al 2007, Sica et al 2012.…”

An Overview of the Immunological Defenses in Fish Skin

“…According to these authors "probiotic for aquaculture is a live, dead or component of a microbial cell that, when administered via the feed or to the rearing water, benefits the host by improving either disease resistance, health status, growth performance, feed utilisation, stress response or general vigour, which is achieved at least in part via improving the hosts or the environmental microbial balance." Some criteria such as the adhesion to host surfaces and adhesive interactions with the pathogens may also represent good criteria for the selection of putative probiotics [325][326][327][328]. The adhesive competitiveness of different potential probiotic strains (isolated from the microbiota of healthy farmed gilthead seabream included as members of the Vibrionaceae and Pseudomonadaceae and the genus Micrococcus) with the pathogen V. harveyi was evaluated [329], and only two isolates (Pdp11, identified as Shewanella putrefaciens, and 51M6) showed an antagonistic effect against V. harveyi [329].…”