As the global demand for food increases, aquaculture is rapidly growing and is replacing capture fishery in providing protein source for meeting human nutritional needs. Existing aquafeeds using fishmeal or soybean meal as sources of protein are unlikely to support this rapid expansion under the current production systems. Single cell protein (SCP) derived from microbial community-based biomass grown on food processing wastewater could be a sustainable alternative. Here, we evaluated the use of microbial protein produced from soybean processing wastewater as partial replacement of fishmeal in the diet of juvenile Asian seabass (Lates calcarifer).
A 24-day feeding trial was conducted with a control fishmeal diet and a 50% fishmeal replacement with microbial community-based SCP as experimental group. Both diets met the protein, essential amino acids (except for lysine), and fat requirements for juvenile Asian sea bass. The bacterial composition of the microbial community-based SCP was dominated by Acidipropionibacterium and Propioniciclava, which have potential as probiotics and producers of valuable metabolites. Triplicate tanks were randomly set up per group, each containing 20 fish.
There was no significant difference between groups in terms of percent weight gain (Figure 1) and feed conversion ratio (FCR), specific growth rate (SGR), and percent survival of fish (Table 1). Furthermore, the experimental group had less variability in terms of weight gain and FCR as compared to the control group, suggesting that a partial fishmeal replacement diet with SCP would be a good alternative protein for use in fish feed. In conclusion, microbial community-based SCP produced from soybean processing wastewater has potential as aquaculture feed ingredient, which can help in the transition of food production systems towards a circular bioeconomy.