Influence of dietary fermented yeast products (Saccharomyces cerevisiae) on performance, health and microbiome of Nile tilapia (Oreochromis niloticus) and the influence of discharge water in the production of romaine lettuce

Authors: PADENIYA, UTHPALA - Auburn University; DAVIS, ALLEN - Auburn University; WELLS, DANIEL - Auburn University; HARRISON, COURTNEY - Auburn University; Lafrentz, Benjamin; Beck, Benjamin; ROY, LUKE - Auburn University; FARMER, MARK - Diamond V; BRUCE, TIMOTHY - Auburn University

Submitted to: Animal Feed Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2025
Publication Date: 4/17/2025
Citation: Padeniya, U.M., Davis, D.A., Wells, D.E., Harrison, C.E., LaFrentz, B.R., Beck, B.H., Roy, L.A., Farmer, M., Bruce, T.J. Influence of dietary fermented yeast products (Saccharomyces cerevisiae) on performance, health and microbiome of Nile tilapia (Oreochromis niloticus) and the influence of discharge water in the production of romaine lettuce (Lactuca sativa). Anim. Feed Sci. Technol., 325:116348. 2025.
DOI: https://doi.org/10.1016/j.anifeedsci.2025.116348

Interpretive Summary: Aquaponic systems are a type of production system where fish and plants are grown together. The basic principle behind this is that the wastes generated from the fish provide nutrients for the plants. The plants take up these wastes and help clean the water. There are two types of aquaponic systems called coupled and decoupled systems. In coupled aquaponic systems the water recirculates as a loop between fish and plant systems. In decoupled systems there is no loop; water from the fish system is used for the plants. To optimize the performance of aquaponic systems for both fish and plants the food that is given to fish is a factor that should be taken into consideration. The current study aimed to determine the effect of feeding probiotics to fish in an aquaponics system and examined the growth, health and the bacterial community living in both tilapia and romaine lettuce. Nine tanks with a working volume of 1000 gal was used in the fish system with 190 tilapia per tank. For the plant system, a deep water culture hydroponic setup with 9 troughs (54.95 gal) was used with 15 romaine lettuce per each trough. The aquaponic system functioned as a decoupled system for this current study. The study tested three types of feed, (1) a basal diet without any fermented yeast products, (2) a diet with 2% DVAQUA®, a yeast-based additive + basal diet and (3) a diet with 0.1% NutriTek, a yeast-based additive + basal diet. After feeding the fish for 16 weeks, the study found no growth differences between different treatments in both fish and plant systems. However, the romaine lettuce grown in water treated with NutriTek had more magnesium in its leaves compared to the basal diet. The fish were also tested for susceptibility to a bacterial pathogen, Flavobacterium oreochromis, a causative agent of columnaris disease. Fish fed with DVAQUA® and NutriTek survived better than those fed with the basal diet. The bacterial diversity and the different types of bacterial species in fish feces and roots of romaine lettuce plants were also examined. Differences were detected in the diversity of bacteria in fish fed the different diets. The most common types of bacteria found in the fish feces were Fusobacteria and Cyanobacteria in plant roots. These bacteria are beneficial and can bring out many benefits to fish and plants. In conclusion, adding fermented yeast products to fish diets can enhance the resistance of Nile tilapia to disease, and these diets can also alter the nutrient contents of the leaves of romaine lettuce plants and the bacteria living in the system. Overall, these findings indicate use of fermented yeast products can make the aquaponic systems healthier for both fish and plants.

Technical Abstract: Aquaponics systems are a model of converting fish waste into plant substrates, and feed input is a critical component to managing water quality and optimizing performance. This study assessed the effects of fermented yeast products (Saccharomyces cerevisiae) on Nile tilapia and romaine lettuce growth, health and microbiome by combining a biofloc system with a deep-water hydroponic setup. Three distinct diets, each consisting of three replicates, were fed to the fish: a basal diet with 32% crude protein and 8% lipid, a diet having 2% DVAQUA® inclusion, and a diet containing 0.1% NutriTek. No discernible growth differences across treatments were discerned in the fish and plant growth trials. Foliar tissue examination showed that NutriTek-treated romaine lettuce plants had noticeably greater levels of magnesium compared to the basal diet treated plants (P = 0.031). From the challenge study with Flavobacterium oreochromis, fish fed DVAQUA and NutriTek exhibited greater survival rates than those fed the basal diet (P = 0.048). No differences in sera lysozyme activity were found, but immune-related markers in the spleen and kidney tissues displayed differences pre- and post-challenge. When bacterial communities were analyzed, differences were found in alpha diversity indices in both fish fecal samples (Shannon diversity index- P < 0.001, Chao – P < 0.001 and observed species P = 0.001) and root samples (Shannon diversity index- P < 0.001, Chao – P < 0.001 and observed species P = 0.005) between treatments (P < 0.05). The most abundant phyla in fecal samples were Fusobacteria and Cyanobacteria for root samples. In conclusion, fermented yeast products which served as dietary supplements improved resistance to diseases in Nile tilapia and influenced the bacterial composition in both the fecal and root microbiome.