Overcoming global food-chain stress by using microbial protein as feed ingredient on aquaculture.

World population will reach 9 billion in 2050 leading to an increase in protein demand. Global meat consumption is expected to double during this period. Meanwhile aquatic animal production represents a steadily increasing global share of dietary protein. Aquaculture production represents 50% of this market and has already increased up to 2.5 times over the last 30 year. One third of the protein source used in aquaculture comes from fishery byproducts while the rest originates from crops (i.e. soybean). Fishmeal prices is increasing steadily while the supply is decreasing. Great part of fishmeal originates from caught fish which reduces biodiversity and submit fishers to work conditions nearly slavery. On the other hand, crops are responsible for 30% of the use of ice-free land, 70% of freshwater use and 30% greenhouse gases emissions. Thus, the inevitable intensification of the production of these conventional protein sources could lead to the acceleration of climate change and to environmental impacts. Find an alternative sustainable protein sources for food-chain and for aquaculture is therefore a major challenge for society.Microbes have a great potential to help mitigating food stress. Besides having the highest protein content of all organisms, up to 75% of the dry weight, it has several advantages comparing with traditional protein source: A) no arable land is required B) near null freshwater demand; C) nearly 100% nutrient uptake. Thus, it could replace part of the protein sources used in feed products. Comparing with other microorganisms aerobic heterotrophic bacteria (AHB) has a remarkable sustainable advantage: they can be grown in secondary resources (i.e. effluents). Consequently, water and nutrients can be recycled locally avoiding water and soil contamination. Conventional wastewater treatment plant (activated sludge process) allows the AHB growth in domestic or industrial wastewater.In the 80's scientists already pointed the potential of AHB as feed ingredient as its nutritional quality is similar to soybean and fish meal. AHB biomass from domestic and industrial wastewater were administered in feeding trial using different organisms (i.e. pigs, chicken, etc.) generating positive results. Most of these studies used AHB biomass from domestic wastewater treatment which contain faecal contamination and heavy metals which raises reasonable concerns about safety. Both contaminants can be easily avoided especially considering food industries' effluents. In Flanders, Breweries are one of the main industries in the food sector. For this reason, brewery wastewater was selected to be the substrate for AHB production.Conventional activated sludge is designed to reach the discharge limits and in reducing operational costs of the plants. Under this conditions, low biomass production is obtained. In order to have a viable technology, biomass productivity and quality need to be maximized. Our research team has been focused in the development of a technology (high-rate activated sludge) able to maximize AHB production and quality. AHB biomass has been produced in high quantities and with great biomass quality, but it is still necessary to prove that AHB produced using our technology can be used as feed ingredient to animals. For this reason, feeding trial experiment is proposed in this project to test the effect of AHB biomass on the fish (rainbow trout). This test is fundamental to prove that AHB can replace positively part of the feed ingredients applied in fish farming. The results are essential to raise awareness among stakeholders (i.e. scientific community, breweries, lawmakers, environmental and food agencies, consumers, etc.) and improve acceptability of it. The success of this research can lead to the continuation of this research which once reaching industrial scale could help mitigate food-chain and environmental stress generated by the conventional protein production.

Keywords:WASTEWATER TREATMENT, ACTIVATED SLUDGE, PROTEINS, NATURAL RESOURCES

Disciplines:Environmental technologies