Written by Charlotte Pugsley, edited by Molly Steadman and Natasha Barrow
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As consumers we are becoming more and more aware of the increasing demand to feed our growing population. It has been estimated that food production will need to increase by somewhere between 59% to 98% to keep up with the demand by 2050 (1). The mass consumption of meat has been hailed as a significant cause of unsustainable food production, with huge greenhouse gas emissions associated with the meat industry (2). To tackle this issue, many of us are turning to alternative diets such as vegetarianism or veganism to curb our consumption of meat. Whilst plant-based protein sources such as soybeans are a good alternative to meat, these have their own environmental repercussions, such as the fossil fuel use associated with transportation and the large use of arable land (3). As usual in times of crisis, innovation has bred biotech start-ups that are tackling this pressing issue.
Single-cell proteins (SCPs) are proteins that are produced in unicellular microorganisms such as algae, fungi and bacteria. The term can be confusing, with SCPs sometimes referring to the crude, whole microbial or algal cells, and other times SCPs are described as the protein that is extracted from the cells themselves through further processing steps (such as cell wall and nucleic acid removal). Whichever form of SCP is used, they all require some kind of microorganism and something to feed it! Microorganisms grow at an exponential rate as individual cells divide into daughter cells, which in turn grow and divide themselves, over and over again. To aid this rapid replication, microorganisms need a food source (often referred to as a feedstock) with a source of carbon, and as such can be cultivated using carbon products that may otherwise go to waste (such as methane or CO2) (4). This means that SCPs can be produced much more sustainably than meat, with a lower carbon footprint. In addition, SCPs have great nutritional value due to a high content of essential amino acids, making them an attractive alternative protein source (5).
Whilst the idea of eating protein produced by bacteria, algae or fungi may seem like a slightly unpleasant concept, I’m sure most of us have spread Marmite® on our toast (or perhaps Vegemite® for our Australian friends) or have eaten (or at least tasted) QuornTM as a meat alternative. We will have probably eaten these products without considering that, in reality, these foods are made from fungi! Marmite® is a product of fungi fermentation, created from Saccharomyces cervisiae (a type of yeast). The meat substitute, QuornTM, is in fact produced from the fungi Fusarium venenatum. Other notable foods cultivated through fermentation of a fungi include: bread, soy sauce and cheese (5).
Over the last decade, start-ups: Corbion, Unibio, Deep Branch and Solar Foods, to name a few, have begun to exploit SCPs from algae and bacteria, rather than fungi, to create fish/animal feed and even food for human consumption…
Algae Afternoon Tea
Algae are aquatic organisms that are able to photosynthesise. If you have seen the green sludge on the surface of a pond, or seaweed at the beach – these are types of algae! Corbion, previously known as TerraVia, is a California-based biotechnology company, using a type of algae to create its protein products. Corbion boasts a large range of algae products for different purposes (6):
Their process involves cultivation of microalgae that is kept in the dark in large fermentation tanks. Corbion feeds their microalgae sustainably sourced sugarcane from Brazil as their feedstock (7).
Bacteria Bran
Unibio is a London-based biotech start-up that is also focusing its efforts on producing SCPs, however Unibio uses a bacteria called Methylococcus capsulatus, rather than fungi or algae, to manufacture Uniprotein® (8). Uniprotein® is used as an animal feed as it has a similar nutritional profile to fish meal and contains 72% protein. Unibio claims that cows fed Uniprotein® produce 10% more milk per day. Natural gas (i.e. methane) is used as a feedstock and is delivered via a trademarked technology called U-Loop® that was developed alongside the Technical University of Denmark (DTU). U-Loop® uses a U-shaped pipe to constantly deliver sources of methane, oxygen and other nutrients to the M. capsulatus bacteria, assisting their rapid growth. Excess liquid is then removed from the resulting concoction and the SCP is heat treated to give Uniprotein®.
Deep Branch are another UK-based biotechnology start-up, based in Nottingham, where the co-founders met at the University of Nottingham’s Synthetic Biology Research Centre (SBRC). A more recent start-up, founded in 2018, Deep Branch relies on bacteria to produce its SCP product – ProtonTM – that is designed as fish and poultry feed (9). In contrast to Unibio, rather than using methane as a feedstock, Deep Branch instead captures CO2 from the environment and combines it with hydrogen (collected through electrolysis of water) as its energy source. The combination of carbon recycling and a sustainable protein source lends itself to Deep Branch’s claim of a 90% saving on carbon footprint with ProtonTM, compared to alternative protein sources.
Last, but by no means least, Solar Foods are a Helsinki-based company, founded in 2017, that manufactures a product called Solein®. Solein® has been created specifically for human consumption, with a purported neutral taste and appearance so that it can easily be added to a meal to increase its nutritional value. Solar Foods uses bacteria to create its SCP, with the whole cells used in Solein® to deliver 65 – 70% protein content. Solar Foods’ tagline claims that Solein® is ‘food out of thin air’ using only ‘air and electricity’ as their feedstock to create ‘the most sustainable protein in the world’. Solar Foods capture CO2 and combine this with water, nutrients and hydrogen (produced using electricity via electrolysis) to feed their microbes (10). Solein® is yet to become commercially available but Solar Foods have gained funding of €35 million from The Finnish Climate Fund and hope to commercialise by 2022 (11).
Once you begin to explore the plethora of single-cell protein products from microorganism fermentation, whether fungi, algae or bacteria, it becomes evident that SCPs could be the answer to sustainable food production for the future. The initial innovation of biotechnology companies to cultivate SCPs as a protein source has been shown to be a viable alternative for animal feed. More recent start-ups, such as Deep Branch and Solar Foods, boast improved sustainability by incorporating carbon capture into their production lines, making these bioprocesses look even more promising for the future. As for human consumption, perhaps by as early as next year in addition to QuornTM we may be including another type of SCP onto our dinner plates!
References
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