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Researchers discover remarkable potential of wastewater from soy milk production in fish industry: 'A significant step forward in sustainable aquaculture practices'

"Reducing the reliance on fishmeal and contributing to the sustainability of the aquaculture industry."

"Reducing the reliance on fishmeal and contributing to the sustainability of the aquaculture industry."

Photo Credit: iStock

Aquaculture (or fish farming) is one of the fastest-growing food sectors in the world, but catching large quantities of smaller fish just to feed them to bigger fish puts us on a path toward exhausting certain populations of wild ocean life by 2050. 

There's some hope, however. New research has shown that repurposing the tons of wastewater from soybean processing for milk and meat alternatives may be the key, as Anthropocene detailed, and it could help offset sustainability issues within that sector as well as the aquaculture industry.  

The production of soybeans has more than doubled over the past two decades, and while much of it is used for animal feed, it's also key to the plant-based protein trend that's been hitting supermarket shelves and soy milk lattes in greater numbers. At the same time, a large portion of the global population gets up to 20% of its protein from fish, which has driven aquaculture to new heights. 

By using a soybean-derived fishmeal instead of overfishing, we could help curtail at least some of the environmental impacts involved and support progress toward a circular bioeconomy. It would lessen the stress on the fish populations, while offsetting the deforestation and carbon pollution from soybean production. 

A team of scientists at the Nanyang Technological University in Singapore found that soybean wastewater contains large quantities of protein-accumulating microbes. Incubating them in bioreactors with soy-sludge was found to be the perfect medium. The result could make a nutritional type of fishmeal.  

In two controlled experiments, one group of juvenile Asian sea bass was fed with a regular fishmeal diet, while the other had a 50/50 mixture including the bacterial protein. The results showed potential, with fish eating the soy-derived mixture getting most of their necessary nutrients and growing at more consistent rates than the fishmeal-only test group. 

These positive results showcase the potential of soybean wastewater as a way to grow food for farmed fish, but it's not the only crop with potential. Researchers mention other agricultural processes that are also rich in nutrients and could support the protein-accumulating bacteria. 

"Our study represents a significant step forward in sustainable aquaculture practices," co-lead author of the study Dr. Ezequiel Santillan said. "By harnessing microbial communities from soybean processing wastewater, we have demonstrated the feasibility of producing single cell protein as a viable alternative protein replacement in fish feed, reducing the reliance on fishmeal and contributing to the sustainability of the aquaculture industry."

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