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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

Colonization studies and microscopic observation of the yeast–zebrafish interactions. (A) Microscopic observation at 0 and 5 dpi of larvae (n = 60) inoculated by immersion with 5 × 106 UFC/ml DTAF-fluorescent yeast. (B) Viable yeast count (UFC/larvae) of larvae inoculated by immersion with 5 × 106 UFC/ml DTAF-fluorescent yeast.
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Figure 4: Colonization studies and microscopic observation of the yeast–zebrafish interactions. (A) Microscopic observation at 0 and 5 dpi of larvae (n = 60) inoculated by immersion with 5 × 106 UFC/ml DTAF-fluorescent yeast. (B) Viable yeast count (UFC/larvae) of larvae inoculated by immersion with 5 × 106 UFC/ml DTAF-fluorescent yeast.

Mentions: For colonization studies, we selected four protective yeast strains isolated from different fish species (Table 1). Mv5 was isolated from O. mykiss, CBS8339 from Salmo gairdneri, Candida deformans 154 (Cd154) from C. gilberti, Yarrowia lipolytica 242 (Yl242) isolated from S. lalandi, and Rhodotorula mucilaginosa 9-1 (Rm9-1) from S. salar. Additionally, the non-protective yeast Mv15, isolated from O. mykiss was also evaluated. Fluorescent yeasts (Supplementary Figure S2) were predominantly observed in the digestive tract of larvae until 5 days post-yeast inoculation (Figure 4A). The viability of the yeasts in larvae revealed that at the day of inoculation (day 0), yeast counts reach 103 CFU/larvae (Figure 4B), compared to non-inoculated larvae in which yeasts were not detected (<10 CFU/larvae). The persistence of viable yeasts in larvae was different among strains: R. mucilaginosa 9-1 (Rm9-1), M. viticola 15 (Mv15), and Y. lipolytica 242 (Yl242) were viable until 5 days post-inoculation (dpi), with yeast counts similar to those registered at the inoculation day. The counts of M. viticola 5 (Mv5) and C. deformans 154 (Cd154) started to decay at 4 dpi.


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)

Colonization studies and microscopic observation of the yeast–zebrafish interactions. (A) Microscopic observation at 0 and 5 dpi of larvae (n = 60) inoculated by immersion with 5 × 106 UFC/ml DTAF-fluorescent yeast. (B) Viable yeast count (UFC/larvae) of larvae inoculated by immersion with 5 × 106 UFC/ml DTAF-fluorescent yeast.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4596066&req=5

Figure 4: Colonization studies and microscopic observation of the yeast–zebrafish interactions. (A) Microscopic observation at 0 and 5 dpi of larvae (n = 60) inoculated by immersion with 5 × 106 UFC/ml DTAF-fluorescent yeast. (B) Viable yeast count (UFC/larvae) of larvae inoculated by immersion with 5 × 106 UFC/ml DTAF-fluorescent yeast.
Mentions: For colonization studies, we selected four protective yeast strains isolated from different fish species (Table 1). Mv5 was isolated from O. mykiss, CBS8339 from Salmo gairdneri, Candida deformans 154 (Cd154) from C. gilberti, Yarrowia lipolytica 242 (Yl242) isolated from S. lalandi, and Rhodotorula mucilaginosa 9-1 (Rm9-1) from S. salar. Additionally, the non-protective yeast Mv15, isolated from O. mykiss was also evaluated. Fluorescent yeasts (Supplementary Figure S2) were predominantly observed in the digestive tract of larvae until 5 days post-yeast inoculation (Figure 4A). The viability of the yeasts in larvae revealed that at the day of inoculation (day 0), yeast counts reach 103 CFU/larvae (Figure 4B), compared to non-inoculated larvae in which yeasts were not detected (<10 CFU/larvae). The persistence of viable yeasts in larvae was different among strains: R. mucilaginosa 9-1 (Rm9-1), M. viticola 15 (Mv15), and Y. lipolytica 242 (Yl242) were viable until 5 days post-inoculation (dpi), with yeast counts similar to those registered at the inoculation day. The counts of M. viticola 5 (Mv5) and C. deformans 154 (Cd154) started to decay at 4 dpi.

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