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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

Screening of protective effect of yeast against V. anguillarum challenge in zebrafish larvae. 4 dpf larvae (n = 60) inoculated by immersion with 5 × 106 UFC/ml yeast and challenged the 5 dpf by immersion with 107 UFC/ml V. anguillarum. (A,B) Survival rate (%) at 6 days post-yeast inoculation. (C,D) Life expectancy (average of survival days of larvae). (A,C) Larvae inoculated with different yeasts and challenged with V. anguillarum; C+, control larvae challenged with V. anguillarum.(B,D) larvae inoculated with different yeast; C-, control larvae non-inoculated. The results show the average ±SD of three independent assays. Asterisks (∗) indicate significant differences with each respective control. Daggers (†) indicate significant differences among protective yeast.
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Figure 3: Screening of protective effect of yeast against V. anguillarum challenge in zebrafish larvae. 4 dpf larvae (n = 60) inoculated by immersion with 5 × 106 UFC/ml yeast and challenged the 5 dpf by immersion with 107 UFC/ml V. anguillarum. (A,B) Survival rate (%) at 6 days post-yeast inoculation. (C,D) Life expectancy (average of survival days of larvae). (A,C) Larvae inoculated with different yeasts and challenged with V. anguillarum; C+, control larvae challenged with V. anguillarum.(B,D) larvae inoculated with different yeast; C-, control larvae non-inoculated. The results show the average ±SD of three independent assays. Asterisks (∗) indicate significant differences with each respective control. Daggers (†) indicate significant differences among protective yeast.

Mentions: The protective effect of 15 yeast strains (Table 1) was evaluated in the V. anguillarum infection model. The results show that 13 yeasts were able to protect larvae from the V. anguillarum challenge, significantly increasing rate survival (%; Figure 3A). Of these protective yeasts, those that increased average survival rate of challenged larvae to >60% were equally effective and did not show significant differences among them (Figure 3A). D. hansenii CBS8339 (CBS8339) and Metschnikowia viticola 15 (Mv5), which induced the lowest protection (<60%), showed significant differences with Cryptococcus laurentii 21 (Cl21), D. hansenii 132 (Dh132), and S. cerevisiae 86 (Sc86; Figure 3A). Of the 13 protective yeasts, 10 yeasts significantly increased the life expectancy of larvae (Figure 3C). The non-protective strains M. viticola 15 (Mv15) and Candida sp. 9 (Csp9; Figure 3A) significantly decreased the survival days of V. anguillarum challenged larvae (P < 0.001; Figure 3C).


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)

Screening of protective effect of yeast against V. anguillarum challenge in zebrafish larvae. 4 dpf larvae (n = 60) inoculated by immersion with 5 × 106 UFC/ml yeast and challenged the 5 dpf by immersion with 107 UFC/ml V. anguillarum. (A,B) Survival rate (%) at 6 days post-yeast inoculation. (C,D) Life expectancy (average of survival days of larvae). (A,C) Larvae inoculated with different yeasts and challenged with V. anguillarum; C+, control larvae challenged with V. anguillarum.(B,D) larvae inoculated with different yeast; C-, control larvae non-inoculated. The results show the average ±SD of three independent assays. Asterisks (∗) indicate significant differences with each respective control. Daggers (†) indicate significant differences among protective yeast.
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Related In: Results  -  Collection

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Figure 3: Screening of protective effect of yeast against V. anguillarum challenge in zebrafish larvae. 4 dpf larvae (n = 60) inoculated by immersion with 5 × 106 UFC/ml yeast and challenged the 5 dpf by immersion with 107 UFC/ml V. anguillarum. (A,B) Survival rate (%) at 6 days post-yeast inoculation. (C,D) Life expectancy (average of survival days of larvae). (A,C) Larvae inoculated with different yeasts and challenged with V. anguillarum; C+, control larvae challenged with V. anguillarum.(B,D) larvae inoculated with different yeast; C-, control larvae non-inoculated. The results show the average ±SD of three independent assays. Asterisks (∗) indicate significant differences with each respective control. Daggers (†) indicate significant differences among protective yeast.
Mentions: The protective effect of 15 yeast strains (Table 1) was evaluated in the V. anguillarum infection model. The results show that 13 yeasts were able to protect larvae from the V. anguillarum challenge, significantly increasing rate survival (%; Figure 3A). Of these protective yeasts, those that increased average survival rate of challenged larvae to >60% were equally effective and did not show significant differences among them (Figure 3A). D. hansenii CBS8339 (CBS8339) and Metschnikowia viticola 15 (Mv5), which induced the lowest protection (<60%), showed significant differences with Cryptococcus laurentii 21 (Cl21), D. hansenii 132 (Dh132), and S. cerevisiae 86 (Sc86; Figure 3A). Of the 13 protective yeasts, 10 yeasts significantly increased the life expectancy of larvae (Figure 3C). The non-protective strains M. viticola 15 (Mv15) and Candida sp. 9 (Csp9; Figure 3A) significantly decreased the survival days of V. anguillarum challenged larvae (P < 0.001; Figure 3C).

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