Plant protein or microbial protein, which is better?


Breaking down the microbiology world one bite at a time

Plant protein or microbial protein, which is better?

If I gave you one hectare of land (10,000 m2) and asked you to feed as many people as possible, what would you do? Some might be tempted to say beef. A huge cow can feed many people. However, the space to grow the feed for that cow and then the space for that cow to graze would be vast, limiting the number of cows you could have on that land. In addition, it takes years to grow that cow to maturity. 

How about soybeans? Soybean has the highest protein amongst all plants and is a major source of protein for the majority of the world. With one hectare of land you could produce 1.1 tons of protein in one year, enough to feed 40 people! This is great but what if I told you there is a process of harnessing protein from microbial biomass that could feed 10x as many people? This process is called photovoltaic-driven single-celled protein or PV-SCP. 

What is Photovoltaic-Driven Microbial Protein? 

Protein is one of those basic building blocks that every organism needs to survive, including microbes. Single-celled organisms are growing in popularity for new biotechnologies because they grow fast, don’t take up a lot of space, are typically cost effective and are better chemists than we ever will be. Making them fantastic microbial biofactories. Chances are this technology is already being sold in your grocery store. If you’re interested in trying some, head to the vegan section or plant based protein section and see if you can find any Quorn products. Quorn is made from harnessing protein from a fungus called Fusarium venenatum which they grow on wheat sucrose as a nutrient source. 

The difference between Quorn and the technology presented in this study is the nutrient source. For many single celled protein derived products plant sugars, or fossil derived sources act as the main microbial nutrients. In this technology the power of the sun is used to supply nutrients to the microbial biomass. Photovoltaic is the  conversion of light energy into electricity using solar panels or other semiconducting materials. So taken together photovoltaic-driven microbial protein is the combination of using solar panels and microbial biomass to produce protein for either animal feedstock or human consumption. 

Picture of solar panels in a field source:

This is done in a four step process. In the first step photovoltaic solar farms capture solar energy and convert it to electricity. Secondly, the electrical energy is converted to chemical energy and stored in hydrogen, formate or methanol. These act as nutrient sources for the third step of the process which is microbial growth. After the energy has been converted from the sun to electricity to chemical energy to biological energy the biomass is then processed into a product. The fourth and final step is filtration. Here all the cellular junk that is not of interest is removed; this includes nucleotides, fatty acids, and carbohydrates. Keeping only the protein of interest in the end.The dry biomass can either be used as feed for livestock or can be processed into dry protein to be used for human consumption. 

The four steps of Photovoltaic-driven microbial protein production. Source: 

Comparing PV-SCP and Agricultural-derived SCP and Soybeans Production

As previously mentioned soybeans are among the highest protein yields of any crop. One cup of soybeans contains 29g of high quality protein! Single-celled protein can be derived in two different methods, one where the nutrients for the microbes come from plant sugars like in Quorn products and one where the nutrients and energy for microbes is derived from solar energy. So how do these three methods compare? 

Dorian Leger, Silvio Matassa, Elad Noor, Alon Shepon, Ron Milo, and Arren Bar-Even in their recent paper  compared the amount of protein these three methods could produce on just one hectare of land or 10,000 m2. In the case of the soybean, 100% of the field is used to cultivate the plant producing 1.1 tons of protein capable of providing sufficient protein to 40 people for one year. In the case of our agricultural sugar derived single celled protein, 94% of that same land is used to produce the agricultural derived sugars and the other 6% is for growing and feeding the microbes. This method can produce 2.7 tons of protein feeding twice as many people as the soybean method. Finally, in the photovoltaic driven single celled protein method, 66% of the land is used for the solar field, 24% for growing the microbial product and 10% for capturing carbon dioxide to aid in microbial cultivation. In this method, authors estimate 15 tons of proteins can be produced feeding approximately 520 people, 10x that of the soybean method! 

When it comes to protein output for hectares of land, microbes produced using the PV-PCP method can produce 10x as much protein as soybeans. Source: 

Could future proteins really come from microbes?

So PV-SCP is land use efficient and produces higher protein yields than conventional methods. It’s also an excellent source of B vitamins which is often lacking in plant-based diets. Nutritionally single celled protein sources also have a high quality amino acid profile and can be rich in micronutrients like iron, zinc, calcium, phosphorus, potassium sodium, magnesium copper and manganese. Not to mention, microbial engineering is farther along than plant engineering. It will be easier to genetically modify microbes to be more efficient in protein production than to genetically modify plants to produce more protein. 

And before you say, I’m not eating microbes, they cause disease! Remember that consuming microbial products are at the foundations of our diets, Saccharomyces cerevisiae is used for bread, beer and wine, lactococcus species for dairy products and Aspergillus oryzae for soy sauce. 

So what are the major barriers to adopting this technology? Price and society are the greatest threats. Authors estimate that price wise PV-SCP cost about $4-5 per kg-protein. When you compare this to the $2.5 or $1 per kg-protein you can obtain with fishmeal and soybean meal respectively the PV-SCP is exuberant. However pea protein and whey protein cost $5 and $7 respectively while mycoprotein like Quorn products are as high as $13 per kg-protein. When you look at all these prices, PV-SCP can easily come to market as a sustainable and cost effective protein alternative. 

Link to the original post: Dorian Leger, Silvio Matassa, Elad Noor, Alon Shepon, Ron Milo, Arren Bar-Even, Photovoltaic-driven microbial protein production can use land and sunlight more efficiently than conventional crops Proceedings of the National Academy of Sciences Jun 2021, 118 (26) e2015025118; DOI: 10.1073/pnas.2015025118

Featured image: Author’s design