Scientists from Nanyang Technological University, Singapore (NTU Singapore) and Temasek Polytechnic have successfully replaced half of the fishmeal protein in the diet of farmed Asian sea bass with a 'single-cell protein' grown from microbes in soybean processing wastewater , paving the way for more sustainable research. fish farming practices.
The use of a cultivated protein is new to aquaculture production, say scientists from the Singapore Center for Environmental Life Sciences Engineering (SCELSE), who are leading NTU efforts in the research, and Temasek Polytechnic's Aquaculture Innovation Center (AIC).
Farmed aquaculture species rely heavily on feed made from wild-caught fish, known as fishmeal, which is unsustainable and contributes to the overfishing of the seas.
Single-cell proteins, a sustainable alternative, can be grown from food processing wastewater. In particular, wastewater from soybean processing contains organisms with probiotic potential that are essential for healthy fish growth.
Wastewater from the food processing industry is free of pathogens and other contaminants, making it suitable for growing microbes. Normally, the wastewater is discharged after processing and flows to a wastewater treatment plant. The nutrients are not recovered, resulting in a missed opportunity to maximize resource use.
Co-lead author of the study, Dr Ezequiel Santillan, senior research fellow at SCELSE, said: “Our study represents an important step forward in sustainable aquaculture practices. By harnessing microbial communities from soybean processing wastewater, we have demonstrated the feasibility of producing single cell protein as a viable alternative protein substitute in fish feed, reducing dependence on fishmeal and contributing to the sustainability of the aquaculture sector.”
The joint research team said their waste-to-resource approach addresses food security and waste reduction, and supports the development of a zero-waste circular economy as set out in the United Nations Paris Agreement.
The study, published in the peer-reviewed scientific journal Scientific reportsaligns with the University's NTU 2025 Research Pillar, a five-year strategic plan that aims to leverage innovative research to reduce human impact on the environment.
The study also aligns with AIC's focus on increasing food security and resilience. With the aquaculture sector aiming to meet 30 percent of Singapore's total nutritional needs by 2030, AIC has been actively pursuing intensive aquaculture production with innovation and technology.
Replacement of half of the usual fish food for Asian sea bass
To demonstrate their approach, the team added soybean processing wastewater from a food processing plant in Singapore to bioreactors – a controlled environment for biological and chemical reactions – to grow single-cell proteins. The laboratory-scale bioreactors were operated for more than four months at 30°C in repeated cycles of controlled nutrient and low air supply (microaerobic conditions). These conditions suggest that the team's method can be easily reproduced at ambient temperatures in tropical areas such as Singapore, further reducing the carbon footprint of fishmeal production.
After producing their single-cell proteins, the research team fed two groups of young Asian sea bass for 24 days. One group was given a conventional fishmeal diet, while the other group was given a diet consisting of half regular fishmeal and half single-cell protein. Both diets provided the same amount of nutritional value for the young fish.
At the end of the experiment, the growth of both groups was evaluated and the researchers found that the fish had grown the same amount. Interestingly, the group of fish on the new diet showed more consistent and less variable growth than the traditional diet group.
NTU Professor Stefan Wuertz from the School of Civil and Environmental Engineering and deputy center director of SCELSE said: “The findings suggest that diets containing single-cell proteins may allow fish to grow more uniformly, and it could be interesting to investigate how this diet fish on a deeper level. economy.”
Co-principal investigator of the study, Dr Diana Chan, Head of the Aquaculture Innovation Center at Temasek Polytechnic, said: “The results of our fish feed performance trials are promising for the aquaculture sector and provide an alternative protein source to meet the increasing need to replace fishmeal that has become very expensive and is not sustainable in terms of supply.”
For their next steps, the research team will conduct trials over longer growth periods with higher fishmeal replacement levels. Researchers will also expand the study to include additional aquaculture species and different types of food processing wastewater.
