The Design and Construction of an Axenic Systems, and the Survival, Growth, and Baseline Bacterial Load of the Rearing Environment, Food Source, and Internal Microbiota of a Larval Cichlid Fish

A Honors Thesis Presentation will be held by Jeffry T. Hayes, Forestry, Fishesier, and Wildlife major. He will present The Design and Construction of an Axenic Systems, and the Survival, Growth, and Baseline Bacterial Load of the Rearing Environment, Food Source, and Internal Microbiota of a Larval Cichlid Fish in 333C Kottman Hall.

I present an axenic apparatus I have designed and constructed for use as a research platform in germ-free larvae culture, which will be used in the development of new disease treatments for economically important aquaculture species. Disease in aquaculture is a major barrier to production. The primary disease treatments are chemotherapeutic drugs such as antibiotics, but these are becoming less effective due to the increased incidence and persistence of antibiotic-resistant pathogens. Overuse of antibiotics in aquaculture, has many negative human, wildlife, and ecosystem implications. For these reasons, antibiotics are being banned for use in non-human animals in many countries. Therefore, novel treatments must be developed. Probiotics are one alternative but researchers often fail to account for the synergistic and antagonistic effects of pre-existing microbiota within the host's gut and rearing environment. The apparatus presented here seeks to remedy this issue. I have tested this system with a cichlid model to evaluate survival, growth, and a baseline bacterial load under holoxenic conditions. This research will provide a foundation for future work with this system and probiotics research in general. It may eventually be used to engineer microbial communities within the gut of captive fish that more closely resemble that of wild counterparts, or even microbial communities that induce desirable phenotypes via microbe induced gene regulation, such as increased growth, survival, reproduction or general health. Overall, reduction or elimination of antibiotic use in aquaculture will create a more sustainable, environment-friendly industry, and may better align with the tastes and preferences of consumers.

Konrad Dabrowski, advisor