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Potential probiotic yeasts isolated from the fish gut protect zebrafish (Danio rerio) from a Vibrio anguillarum challenge.

Caruffo M, Navarrete N, Salgado O, Díaz A, López P, García K, Feijóo CG, Navarrete P - Front Microbiol (2015)

Bottom Line: Yeasts reached 10(3) CFU/larvae at 0 dpi, although the persistence until 5 dpi of the viable yeast in the gut was different among the strains.These results reveal that some yeasts isolated from the gut of fish could be potential probiotics, reducing the mortality associated to V. anguillarum challenge, and suggest that gut colonization could be involved in the protective effect.Future studies should elucidate other mechanisms involved in yeast protection and verify the beneficial effects of probiotic use in commercial fish species.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Microbiología y Probióticos, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile Santiago, Chile.

ABSTRACT
Due to the negative consequences associated with the use of antibiotics, researchers, and food producers have studied alternatives, such as probiotics, for the control of fish diseases. The probiotic properties of yeasts in aquaculture have been scarcely considered. The present study investigated the probiotic properties of local yeast strains for aquaculture application in the protection of bacterial diseases. Yeast strains (n = 15), previously isolated from the intestinal gut of healthy salmonids, yellowtail, and croaker, were evaluated for their protection of zebrafish larvae following a Vibrio anguillarum challenge. We developed an infection model on zebrafish larvae with V. anguillarum, observing rapid mortality (≥50%) 5 days post-immersion challenge. Infection of Tg(Lyz:DsRed)(nz50) larvae with fluorescent-marked V. anguillarum showed the oro-intestinal as the natural route of infection concomitant with an inflammatory response of the larvae reflected by neutrophil migration outside the hematopoietic tissue. Thirteen of 15 strains increased the percentage of larvae survival after the V. anguillarum challenge, although no yeast showed in vitro anti-V. anguillarum activity. In a subset of yeasts, we explored yeast-larvae interactions using fluorescent yeast and evaluated larvae colonization by culture analysis. All fluorescent yeasts were located in the gastrointestinal tract until 5 days post-inoculation (dpi). Yeasts reached 10(3) CFU/larvae at 0 dpi, although the persistence until 5 dpi of the viable yeast in the gut was different among the strains. These results reveal that some yeasts isolated from the gut of fish could be potential probiotics, reducing the mortality associated to V. anguillarum challenge, and suggest that gut colonization could be involved in the protective effect. Future studies should elucidate other mechanisms involved in yeast protection and verify the beneficial effects of probiotic use in commercial fish species.

No MeSH data available.


Related in: MedlinePlus

Stereoscopic observation of the 5-([4,6-Dichlorotriazin-2-yl] amino) fluorescein hydrochloride (DTAF)-labeled V. anguillarum in zebrafish larvae. (A) 5 dpf wild type (WT) larvae were inoculated by immersion with 107 UFC/ml DTAF stained V. anguillarum: (i) lateral view scheme of the gut; (ii) lateral view of challenged larvae. (B) 5 dpf Tg(Lyz:DsRed)nz50 larvae inoculated by immersion with 107 UFC/ml DTAF-stained V. anguillarum (challenge) or sterile E3 as a control (control). (C) Quantification of neutrophils migration was performed in the selected area (yellow rectangle).
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Figure 2: Stereoscopic observation of the 5-([4,6-Dichlorotriazin-2-yl] amino) fluorescein hydrochloride (DTAF)-labeled V. anguillarum in zebrafish larvae. (A) 5 dpf wild type (WT) larvae were inoculated by immersion with 107 UFC/ml DTAF stained V. anguillarum: (i) lateral view scheme of the gut; (ii) lateral view of challenged larvae. (B) 5 dpf Tg(Lyz:DsRed)nz50 larvae inoculated by immersion with 107 UFC/ml DTAF-stained V. anguillarum (challenge) or sterile E3 as a control (control). (C) Quantification of neutrophils migration was performed in the selected area (yellow rectangle).

Mentions: In order to assess the route of infection of V. anguillarum in the larvae, we labeled V. anguillarum with DTAF (Supplementary Figure S1). This labeling did not affect the viability of the bacteria checked by culturing them in CHROMagarTM Vibrio medium (data not shown). Observation of WT larvae challenged with DTAF-V. anguillarum showed fluorescent bacteria in the gastrointestinal tract, and branchial arches from 1 to 3 h post-inoculation (Figure 2A) indicating that oral and gills were the main entry pathways of this pathogen. The infection of Tg(Lyz:DsRed)nz50 larvae with V. anguillarum induced mobilization of a high number of neutrophils outside the caudal hematopoietic tissue, in contrast to controls (P < 0.05), reflecting the stimulation of the innate immune system (Figures 2B,C).


Potential probiotic yeasts isolated from the fish gut protect zebrafish (Danio rerio) from a Vibrio anguillarum challenge.

Caruffo M, Navarrete N, Salgado O, Díaz A, López P, García K, Feijóo CG, Navarrete P - Front Microbiol (2015)

Stereoscopic observation of the 5-([4,6-Dichlorotriazin-2-yl] amino) fluorescein hydrochloride (DTAF)-labeled V. anguillarum in zebrafish larvae. (A) 5 dpf wild type (WT) larvae were inoculated by immersion with 107 UFC/ml DTAF stained V. anguillarum: (i) lateral view scheme of the gut; (ii) lateral view of challenged larvae. (B) 5 dpf Tg(Lyz:DsRed)nz50 larvae inoculated by immersion with 107 UFC/ml DTAF-stained V. anguillarum (challenge) or sterile E3 as a control (control). (C) Quantification of neutrophils migration was performed in the selected area (yellow rectangle).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4596066&req=5

Figure 2: Stereoscopic observation of the 5-([4,6-Dichlorotriazin-2-yl] amino) fluorescein hydrochloride (DTAF)-labeled V. anguillarum in zebrafish larvae. (A) 5 dpf wild type (WT) larvae were inoculated by immersion with 107 UFC/ml DTAF stained V. anguillarum: (i) lateral view scheme of the gut; (ii) lateral view of challenged larvae. (B) 5 dpf Tg(Lyz:DsRed)nz50 larvae inoculated by immersion with 107 UFC/ml DTAF-stained V. anguillarum (challenge) or sterile E3 as a control (control). (C) Quantification of neutrophils migration was performed in the selected area (yellow rectangle).
Mentions: In order to assess the route of infection of V. anguillarum in the larvae, we labeled V. anguillarum with DTAF (Supplementary Figure S1). This labeling did not affect the viability of the bacteria checked by culturing them in CHROMagarTM Vibrio medium (data not shown). Observation of WT larvae challenged with DTAF-V. anguillarum showed fluorescent bacteria in the gastrointestinal tract, and branchial arches from 1 to 3 h post-inoculation (Figure 2A) indicating that oral and gills were the main entry pathways of this pathogen. The infection of Tg(Lyz:DsRed)nz50 larvae with V. anguillarum induced mobilization of a high number of neutrophils outside the caudal hematopoietic tissue, in contrast to controls (P < 0.05), reflecting the stimulation of the innate immune system (Figures 2B,C).

Bottom Line: Yeasts reached 10(3) CFU/larvae at 0 dpi, although the persistence until 5 dpi of the viable yeast in the gut was different among the strains.These results reveal that some yeasts isolated from the gut of fish could be potential probiotics, reducing the mortality associated to V. anguillarum challenge, and suggest that gut colonization could be involved in the protective effect.Future studies should elucidate other mechanisms involved in yeast protection and verify the beneficial effects of probiotic use in commercial fish species.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Microbiología y Probióticos, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile Santiago, Chile.

ABSTRACT
Due to the negative consequences associated with the use of antibiotics, researchers, and food producers have studied alternatives, such as probiotics, for the control of fish diseases. The probiotic properties of yeasts in aquaculture have been scarcely considered. The present study investigated the probiotic properties of local yeast strains for aquaculture application in the protection of bacterial diseases. Yeast strains (n = 15), previously isolated from the intestinal gut of healthy salmonids, yellowtail, and croaker, were evaluated for their protection of zebrafish larvae following a Vibrio anguillarum challenge. We developed an infection model on zebrafish larvae with V. anguillarum, observing rapid mortality (≥50%) 5 days post-immersion challenge. Infection of Tg(Lyz:DsRed)(nz50) larvae with fluorescent-marked V. anguillarum showed the oro-intestinal as the natural route of infection concomitant with an inflammatory response of the larvae reflected by neutrophil migration outside the hematopoietic tissue. Thirteen of 15 strains increased the percentage of larvae survival after the V. anguillarum challenge, although no yeast showed in vitro anti-V. anguillarum activity. In a subset of yeasts, we explored yeast-larvae interactions using fluorescent yeast and evaluated larvae colonization by culture analysis. All fluorescent yeasts were located in the gastrointestinal tract until 5 days post-inoculation (dpi). Yeasts reached 10(3) CFU/larvae at 0 dpi, although the persistence until 5 dpi of the viable yeast in the gut was different among the strains. These results reveal that some yeasts isolated from the gut of fish could be potential probiotics, reducing the mortality associated to V. anguillarum challenge, and suggest that gut colonization could be involved in the protective effect. Future studies should elucidate other mechanisms involved in yeast protection and verify the beneficial effects of probiotic use in commercial fish species.

No MeSH data available.


Related in: MedlinePlus