An emerging protein source: Single-cell protein

It was over 100 years ago when yeast protein was discovered by chance by a German scientist called Justus Liebig. Once commercialised, it became the food product Marmite that’s applied to bread like peanut butter.

But SCPs also have a decades-old history in Finland for use in animal feed and they are being used again there and elsewhere for many reasons. SCPs have a very high protein content (60-80%) on a dry matter basis, which is at least double the protein level of crops such as soybeans or lupins (about 36%). SCPs contain large amounts of critical livestock amino acids such as methionine and lysine, along with fats carbohydrates, minerals like phosphorus and potassium, and vitamins.

Their exact composition of course, depends on the type of SCP that’s cultivated and the species. According to global animal feed company dsm-firmenich, the SCP category covers over 1 billion species, spanning bacteria, fungi, yeast and algae. It is not known how many candidates have the potential for commercial protein production, but several have already been identified.

Inside the process

In production of SCP, colonies of a given single-cell organisms are cultured in vats, feeding on a variety of traditional raw materials such as starch, fruit matter and molasses. However, new feedstocks are actively being explored, including wood cellulose, petroleum by-products, ethanol, natural gas, carbon dioxide (algae) and methanol.

Periodically, the organisms are isolated from the culture and dried (and the protein they contain may be further isolated and purified) and then added to livestock feed. They can replace other proteins from fishmeal to guar meal, including plant proteins from wheat gluten, soybean and pea protein concentrates.

Many benefits in the production process; many related to sustainability

SCP production requires far fewer resources compared to obtaining protein for livestock from the harvest of marine fish or growing crops. And, “because production does not rely on climate patterns or long supply chains, SCPs are less volatile than conventional commodities,” notes Karim Kurmaly, dsm-firmenich SCP Director, “thus supporting food security, supply chain resilience and (they) can provide a consistently high-quality protein specification 365 days per year.” SCP production is also flexible in that it can be done at any scale and is easy to scale up or scale back.

SCP production can be located anywhere, but are ideally situated next to where raw materials are being produced and where livestock farming is occurring so that transport is minimised. Ideally also, from a sustainability perspective, is to locate production sites where there are available sources of waste heat from factories or even geothermal vents. Using raw materials that are by-products from food processing or other plants reflects a circular economy approach, using these resources to feed livestock as opposed to a dead end for these materials once they are shipped to a landfill to rot.

The industry is in its infancy, and there is little SCP being used in livestock feed at this point, but we seem to be on the cusp of ushering in widespread use during the next few years.

HERE IS A LOOK AT THE ACTIVITIES OF 3 FIRMS

Keys to success

One crucial factor that in Kurmaly’s view could accelerate adoption of SCP is legislation that supports greater sustainability in the agri-food sector and addresses the expectations of stakeholders such as livestock producers, feed millers, processors, retailers, nonprofit groups and consumers who are increasingly focused on measuring and reducing the environmental impact of the livestock industry.

Critical private and public research will also continue. In a 2022 review paper by a team from several countries, many universities were listed from around the world as involved with R&D, but most of the research is located in the USA. Institutions carrying out SCP R&D include Iowa State, MIT, Cornell in the US, Dalhousie and U of Quebec in Canada, Ocean University of China, the Norwegian University of Life Sciences, Punjab Agricultural University and the Technical University of Denmark.

The team noted that “with the ever-growing world population and projections on the inability of conventional agriculture to cater to the food needs of the future, especially in Africa and Asia, more collaborative research activities are needed to increase food production using SCP through capacity building and increasing infrastructure for SCP production especially within these regions.”

Among other aspects, the team says future research should focus on the use of genetic engineering approaches to improve potential strains with desirable characteristics, for example, removing toxin-producing genes if these are present.

Indeed, many additional benefits can be found in SCP production if breeding or other types of genetic modification can result in yeast, bacteria, algae or fungi that grow faster, produce even more protein from raw materials and/or can be enabled to convert new sources of raw materials to protein.