Engineering gut microbiome of waste-fed mealworms as sustainable fish feed in aquaculture

• Main Author: Feng, Shiliu
• Other Authors: Loo Say Chye Joachim
• Format: Thesis-Master by Research
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Materials
• Online Access: https://hdl.handle.net/10356/166389
• Institution: Nanyang Technological University

Singapore's goal towards 30% food self-sufficiency by 2030 has called upon novel and sustainable strategy to our local food production. The consumption of fish and aquaculture farming take up large portions of business in Singapore. Fishmeal was regarded as unsustainable due to increasing demanding of fish stocks worldwide and fierce competition of usage in other livestock feeds. On the other hand, insect protein would be a viable substitute for fishmeal, especially if the food source is obtained in a sustainable manner, preferably through a circular economy. Because of its robustness, capacity to eat atypical food sources, mealworm was proposed as an alternate protein source for fishmeal replacement in this study. Food processing wastes (i.e., okara) and plastic wastes generated from industrial production is proposed to be suitable sustainable food substrates for mealworms. Preliminary research has indicated that mealworms can eat non-biodegradable polymers, such as polystyrene and polyethylene, making them ideal for waste repurposing. In this project, it was postulated that change of mealworms' gut microbiome could enhance efficient digestion of food and plastic wastes, and that these waste-fed mealworms could be utilized as a fishmeal replacement for fish feeds. This study aims to investigate the changes in the gut microbiome of mealworms fed okara, low-density polyethylene (LDPE), and polyethylene terephthalate (PET), whereby: 1) the digestion of different waste substrates by mealworms was examined; 2) determining the nutrition profile and biosafety of waste-fed mealworms; 3) identifying microorganisms that enhance waste digestion and 4) engineering the gut microbiome of mealworms to promote waste-digestion efficiency. Nutritional compositions and metabolomics of waste-fed mealworms were examined to determine suitability of waste-fed mealworms as a safe fishmeal replacement in fish diets. The results indicated waste impeded mealworm growth performance and raised safety concern of potential toxic substance accumulated in mealworm biomass. Plastic-degrading strains were isolated from mealworm gut and their inoculation to mealworms promoted waste digestion. The promising result of engineering mealworm gut microbiome could help to overcome current challenges of mealworm waste-digestion and contribute to circular economy.