Probiotic effect in vivo of Roseobacter strain 27-4 against Vibrio (Listonella) anguillarum infections in turbot (Scophthalmus maximus L.) larvae

Abstract

33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50The purpose of this study was to evaluate the probiotic effect of the marine bacterium Roseobacter strain 27-4 in turbot larvae infected with the pathogen Vibrio (Listonella) anguillarum. Initial trials demonstrated that cells of Roseobacter were not harmful to larvae whereas, large amounts of bacterial culture supernatant caused rapid mortality (70% at day 10 compared to 20% in the control). A similar high mortality was, however, also seen, when sterile marine broth was added to the larvae. Presumably both types of medium enhanced growth of opportunistic pathogens. In subsequent trials, both a pathogen, Vibrio anguillarum, and the probiont, Roseobacter strain 27-4, were delivered to the larvae bioencapsulated in rotifers. Accumulated mortality of Vibrio infected larvae increased to 80-90% over 10 days, whereas, mortality in non-infected controls was significantly lower (60-70%). Feeding larvae with rotifers enriched with Roseobacter 27-4 parallel to V. anguillarum infection, brought the accumulated mortality to the level of control indicating a clear in vivo effect. Roseobacter 27-4 could be detected in larvae both by agar plating and by immunohistochemistry, being located in the gastrointestinal lumen, and apparently did not colonise the larval gut and intestinal epithelium. Plate counts decreased when enriched feed was no longer added, suggesting that the probiont, Roseobacter 27-4, should be supplied repeatedly to exert its positive effect. Introduction

Probiotics in Aquaculture of Kuwait - Current State and Prospect

“…Repetitive addition of the probiotics can significantly enhance the rotifers performance and survival. The result of this study is in agreement with the results obtained by Planas et al, (2006). They reported that continuous additions of probiotic (Rosebacter strain) are necessary to maintain a minimum level of it in the rotifer and the culture water.…”

Global occurrence and heterogeneity of the Roseobacter-clade species Ruegeria mobilis

“…To reduce the use of antibiotics, we and others have focused on use of probiotic strategies and used bacteria of the Roseobacter clade that can antagonize fish-pathogenic bacteria without harming the fish or their live feed (D'Alvise et al, 2012(D'Alvise et al, , 2013. Specifically, strains belonging to the species Ruegeria mobilis and Phaeobacter inhibens are potent antagonists of the fish pathogens (Planas et al, 2006;Porsby et al, 2008;D'Alvise et al, 2010) primarily caused by production of the antibacterial compound tropodithietic acid (TDA) (D'Alvise et al, 2010(D'Alvise et al, , 2012. TDA is also bactericidal against human pathogens including Salmonella enterica and Staphylococcus aureus (Porsby et al, 2011) and it has been recently been demonstrated that TDA acts by disrupting the proton motive force (Wilson et al, 2016).…”

In vitro assessment of gastrointestinal viability of two photosynthetic bacteria, Rhodopseudomonas palustris and Rhodobacter sphaeroides

“…Most probiotics used in aquaculture belong to the lactic acid bacteria, to the genus Bacillus, or to the genus yeast, although other genera or species have also been mentioned (Bogut et al, 1998;Carnevali et al, 2006;Planas et al, 2006;Vázquez et al, 2005). Few studies have been carried out on the potential of photosynthetic bacteria (PSB), Rhodopseudomonas palustris and Rhodobacter sphaeroides, as probiotics in aquaculture.…”