Evaluation Of The Probiotic Potential Of A Competitive Exclusion Culture From Tilapia (Oreochromis Niloticus) Intestinal Microbiota

Stress conditions in intensive aquaculture are generating serious economic loss due to diseaseoutbreaks. For that reason, antibiotics are often used to reduce infection. Nevertheless, theadministration of repeated doses of antibiotics, at non-optimal concentrations increases the risk ofcreating antibiotic-resistant bacteria that may be harmful for the environment and the finalconsumer.Probiotic bacteria are an efficient alternative to antibiotics since several publications, have shownto improve fish health status and favor the famer productivity. Particularly beneficial autochthonousbacteria consortia constituted as a competitive exclusion culture, will be selected in the presentproject from healthy tilapia (Oreochromis spp.) intestines.This project will be divided into two phases: The first phase involves the in vitro characterization ofthe competitive exclusion culture to evaluate the probiotic potential by culture dependent andindependent techniques, considering mechanisms of action against selected tilapia pathogens,and safety conditions required for a selected probiotic. The second phase will be the in vivoevaluation of feed administration of the selected bacteria on the production parameters such asfeed conversion, weight gain, growth rate, survival and resistance during experimental infectionsusing bacteria associated with mass mortalities in tilapia farms. Furthermore, de novotranscriptome assembly will measure the immunomodulatory activity through differential geneexpression.

Stress conditions in intensive aquaculture are generating serious economic loss due to diseaseoutbreaks. For that reason, antibiotics are often used to reduce infection. Nevertheless, theadministration of repeated doses of antibiotics, at non-optimal concentrations increases the risk ofcreating antibiotic-resistant bacteria that may be harmful for the environment and the finalconsumer.Probiotic bacteria are an efficient alternative to antibiotics since several publications, have shownto improve fish health status and favor the famer productivity. Particularly beneficial autochthonousbacteria consortia constituted as a competitive exclusion culture, will be selected in the presentproject from healthy tilapia (Oreochromis spp.) intestines.This project will be divided into two phases: The first phase involves the in vitro characterization ofthe competitive exclusion culture to evaluate the probiotic potential by culture dependent andindependent techniques, considering mechanisms of action against selected tilapia pathogens,and safety conditions required for a selected probiotic. The second phase will be the in vivoevaluation of feed administration of the selected bacteria on the production parameters such asfeed conversion, weight gain, growth rate, survival and resistance during experimental infectionsusing bacteria associated with mass mortalities in tilapia farms. Furthermore, de novotranscriptome assembly will measure the immunomodulatory activity through differential geneexpression.

AQUACULTURESTREPTOCOCCUS AGALACTIAETRANSCRIPTOMETILAPIACOMPETITIVE EXCLUSION CULTUREPROBIOTICSBIOTECNOLOGY