Document Type
Dissertation - Open Access
Award Date
2025
Degree Name
Doctor of Philosophy (PhD)
Department / School
Animal Science
First Advisor
Benoit St-Pierre
Abstract
In the aquaculture industry, plant-based protein sources have emerged as an economically and environmentally sustainable replacement for traditional animal protein sources. Yet, due to reduced digestibility, the presence of anti-nutritional factors, as well as an increased risk of inflammation of the digestive system, the inclusion of plant-based protein ingredients must be limited, especially in the diets of carnivorous fishes. To gain further insight on how to adapt the fish digestive tract to more effectively utilize or tolerate plant-based protein ingredients, slurry from cultured Atlantic Salmon (Salmo salar) was used as a proxy in an in vitro model system to identify candidate gut bacterial species from fish that can metabolize plant-based protein sources. The study revealed nine candidate bacterial species that could be enriched in cultures supplemented with soybean-based ingredients, which was indicative of their capacity to metabolize soy-based compounds. To elucidate their functional capabilities, we subsequently focused on building partial genomes of these enriched candidate bacteria. Among the various metabolic pathways uncovered, the capacity to utilize carbohydrate-type anti-nutritional factors was identified. In addition, the potential to express secretory systems that have been previously found in pathogens was deemed of particular interest. Using metatranscriptomics, the genes responsible for these functions were confirmed to be expressed in cultures grown in the presence of soybean-based ingredients. By elucidating the mechanisms underlying microbial utilization plant protein sources, this research provides a foundation for developing strategies to modulate the gut microbiome towards enhancing the digestibility of plant-based diets for salmonids.
Publisher
South Dakota State University
Recommended Citation
Fowler, Emily, "Identification of Gut Bacterial Symbionts from Atlantic Salmon That Are Involved in Metabolizing Feed Ingredients Derived from Soybean Meal" (2025). Electronic Theses and Dissertations. 1548.
https://openprairie.sdstate.edu/etd2/1548
Rights Statement
