Is it possible to use microbes to grow protein from air and electricity?

Question

Solar Foods claim they can use microbes to ferment an edible protein powder.

Their process is described as follow:

The process takes a single microbe, one of the billion different ones found in nature, and grows it by fermenting it, which is also called a bioprocess. We feed the microbe like you would feed a plant, but instead of watering and fertilising it, we use mere air and electricity. With our current process, this is 20x more efficient than photosynthesis (and 200 times more than meat).

Later in the same page they adjust the claim:

Air

The microorganism grows like a plant but instead of water and soil, we feed it with electricity and the main ingredients captured from air: carbon, hydrogen, oxygen and nitrogen.

[...]

Nutrients and minerals

A few percent of the end-product consist of inorganic nutrients, such as phosphorus and calcium, which cannot be taken from the air.

This seems to good to be true.

Answer 1

Is it possible to use microbes to grow protein from air and electricity?

Yes, absolutely, and we've been at it for well over half a century.

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Solar Foods is a Finnish food-tech startup that is pilot testing a technology that uses electricity to produce hydrogen which is combined with carbon dioxide, water, vitamins and minerals to feed and grow a microbial biomass that can be used as edible protein.3 The company was founded in 2017.[4][5]

Wikipedia - Solar Foods

The company claims :

Our unique bioprocess can grow a single microorganism, one of the billions found in nature, into an endless supply of edible food with air, electricity and fermentation. This bioprocess may not be traditional, but it is as natural as the air we breathe.

Solar Foods

But I cannot see any real difference between what they are doing (or seeking to do) than what was done in the 1970s by Ranks Hovis McDougall (the food group in the UK then owned by Lord Rank).

Straight from school, I was employed at the Lord Rank Research Centre, as an Analytical Chemist, in Buckinghamshire, England, in 1970 and some of my work was in connection with 'A 3/5', technically known by my Microbiology colleagues as Fusarium Venenatum, the end-product being today on sale in my local supermarket as 'Quorn'.

I spent many happy hours analysing both the fatty acid composition and the phospholipid content of 'A 3/5' by means of Gas-Liquid Chromatography.

Myco-protein is produced from microfungi, aerobic organisms that live in the soil and convert carbohydrate to protein. Research to produce food from microfungi began in the early 1960s. This was at a time when many projects were being set up to develop single-cell protein sources suitable for animal and human consumption in response to the predicted protein gap in developing countries. There are reports of three products produced form microfungi, but by far the most successful myco-protein product is sold under the trade name ‘Quorn™.’

Myco-protein is the generic name of the major raw material used in the manufacture of Quorn™ products. It comprises the RNA-reduced biomass composed of the hyphae (cells) of the organism Fusarium venenatum A3/5 (deposited with the ATCC as PTA-2684) grown under axenic conditions in a continuous fermentation process. Quorn™ is the brand name of a range of meat-alternative products made from myco-protein. Quorn™ products include pieces and mince for use in home cooking in addition to a range of convenience products such as burgers, fillets, goujons, nuggets, and ready meals.

Science Direct

Some of the claims being made by Solar Foods (particularly 'unique bioprocess') seem to me to be invalid. There is nothing new about mycoprotein, it has been around since 1960.

One minute they claim 'mere air and electricity' and the next minute they more expansively state 'hydrogen which is combined with carbon dioxide, water, vitamins and minerals'.

Well, either it's two ingredients or it's seven.

They also kind of give the impression that they are starting each day's experiments with a single specimen of microbe in a dish, which is just plain silly. My take on the scenario is vats and pumps and pipework, starting with billions of the things, left over from yesterday's efforts, stored overnight at four degrees C in a dustbin-sized tank.

I've watched similar processes and it is not white coats and serious expressions and clipboards : it is welly boots and chuntering pumps and sloshing in puddles when the pipework leaks.

The process is well known and thoroughly researched : it is continuous fermentation under axenic conditions giving rise to a high protein product.

I don't eat the stuff myself, but in future I may have to, if efforts to globally eliminate traditional farming (with its inevitable by-product of gaseous methane) are successful.

Answer 2

Yes, there is a known type of microbe that feeds on the byproducts of the electrolysis of water, and carbon dioxide, like Solar Foods describes, and Solar Foods is said to be using this kind of microbe.

As @Nigel J said, the basic idea is not new, but like Solar Foods says, this microbe does not need to feed on sugar like yeast or the Quorn process.

The 2021 article "Food in space from hydrogen-oxidizing bacteria" by Kyle A. Alvarado, Juan B. García Martínez, Silvio Matassa, Joseph Egbejimba, David Denkenberger (https://doi.org/10.1016/j.actaastro.2020.12.009. PDF) discusses the potential use of Hydrogen-oxidizing bacteria (HOB) for food production in space, and mentions that Solar Foods' product is from HOB. It states that the first food production method using HOB was developed in 1965.

Instead of needing to digest organic chemicals, like animals do, or carry out photosynthesis, like plants do, HOBs can grow and feed from chemical reactions involving hydrogen gas. Those that can react hydrogen gas + oxygen gas, which are the byproducts of electrolysis of water, derive energy from that reaction. Some can react hydrogen gas + carbon dioxide to produce organic chemicals for their own growth.

I don't know how to evaluate the efficiency of Solar Foods' process. (I'm curious where they source their carbon dioxide from, and if or how they included energy used for that in their efficiency calculation.) But it appears they are being honest when they say that their product grows based on a microbe, certain nutrients, and gaseous ingredients like those from the electrolysis of water. And as they tout, electrolysis can of course be done with electricity from renewable sources.

The phrase "split water from air" on their current webpage, on the other hand: taken literally it sounds like instead of using a normal water source, they're condensing water vapor from ambient air to use in their electrolysis step. I think it would be much more efficient to just use a regular liquid water source, and/or condense water vapor created somewhere else in their process.