Development of a multistrain Nile tilapia (Oreochromis niloticus) gut microbiota-derived probiotic with antibacterial activity against fish pathogens

Authors: MELO-BOLIVAR, JAVIER FERNANDO - Universidad De La Sabana; RUIZ PARDO, RUTH YOLANDA - Universidad De La Sabana; Hume, Michael; QUINTANILLA-CARVAJAL, MARIA XIMENA - Universidad De La Sabana; EDUARDO DIAZ, LUIS - Universidad De La Sabana; VILLAMIL DIAZ, LUISA MARCELA - Universidad De La Sabana

Submitted to: Innovative Food Science and Emerging Technologies
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/21/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary: A probiotic bacteria mixture was created from three bacteria selected from a culture of tilapia intestine contents. These bacteria previously were shown to kill pathogenic bacteria found in tilapia. The probiotic culture was created as a potential replacement for antibiotics to improve tilapia growth and to reduce infection by pathogenic bacteria. A new approach was to use software designed to create a balanced proportion of the bacteria in the probiotic mixture to optimize effectiveness. Sugar and fish feed are two methods being considered for feeding the probiotic bacteria to the fish. The probiotic mixture was added to the sugar and fish feed and compared for bacterial survival during storage. The two mixtures were freeze-dried, and bacteria cell counts were monitored over 28 days while stored at 4C or 25C. At 4C storage, the probiotic mixtures were stable in the sugar and the fish feed, while being less stable at 25C. A software mixture design may be used to better define a probiotic containing multiple bacteria, and freeze-drying, combined with either sugar or fish feed and then followed by refrigeration, may be used to stabilize these tilapia-derived probiotic mixtures during storage. The study results are of interest to researchers and producers applying probiotics in aquaculture to improve production and combat disease.

Technical Abstract: Multistrain probiotic mixtures were assembled from isolates selected from a Nile tilapia (Oreochromis niloticus) gut microbiota-derived competitive exclusion culture. Lactococcus sp. A12, Bacillus sp. M4, and Bacillus sp. M10 demonstrating antibacterial activity against the fish pathogens Streptococcus agalactiae and Aeromonas hydrophila were proportion optimized using mixture design software. Two probiotic mixtures were chosen and compared for storage viability: one containing 61% of strain A12, 16% of M4, and 23% of M10; the other containing 28% of M4 and 72% of M10. The mixtures were combined with maltodextrin or fish feed (150 mL of probiotic/100 g of maltodextrin or feed) then freeze-dried, and bacterial counts were monitored over 28 days while stored at 4C or 25C. At 4C storage, the multistrain probiotics were stable in maltodextrin and fish feed. In conclusion, a mixture design may be used to define a multistrain probiotic, and freeze-drying while combined with maltodextrin and fish feed followed by refrigeration could be employed to stabilize these tilapia-derived probiotics.