Over the last several years, precision fermentation has attracted attention as a manufacturing methods that could drastically lower the environmental impacts of everyday products, from edible proteins to animal feed and cosmetics ingredients.
Precision fermentation is a biomanufacturing technique that uses living microbes and their metabolism to create biobased chemicals and materials.
However, scaling the method while keeping its environmental impacts low is a challenge. One factor deciding the sustainability of precision fermented goods is the type of material used to feed the industrial microbes that produce them.
What is precision fermentation?
We’re all familiar with the products of traditional fermentation-based biomanufacturing, such as beer making or cheese making. These age-old techniques use certain communities or species of bacteria to break down a simple feedstock (grains, milk). Their unique metabolism transforms these basic compounds inside their bodies into foods with a particular look or taste.
Similarly, modern precision fermentation uses the metabolic abilities of microorganisms to create high-value products. In modern biomanufacturing, however, producers can genetically modify their bacteria in very targeted ways. Among the first products of precision fermentation to have been commercialised were biofuels. Now, with gene editing, producers can create microorganisms capable of churning out pretty much any biochemical.
With targeted gene editing, bacterial strains can become extremely versatile and adjustable living ‘machines’ that can churn out different biobased products with very specific physical traits at high volumes.
Now, it is possible to create a vast range of materials using vats of microbes: compostable plastics, textiles made from modified proteins, and plant-based proteins with chemical compositions similar to animal meat. A whole raft of startups now even offer slaughter-free replicas of meat and seafood, asking their modified microbes to replicate a tiny cell sample taken from living animals.
Once the microbes manage to cultivate the target chemical to a certain critical mass inside their cells, the producer harvests it and discards the host cells they grew inside.
Fermented factories can be green – but there’s a catch
Precision fermented products can be highly sustainable compared to fossil-based analogues, with lower footprints in carbon dioxide as well as land use.
However, this is not always guaranteed. One variable that determines the sustainability of any particular precision fermentation process comes back to the kind of feedstock used to feed the microbes.
Feedstock here refers to whatever sugar-based food is given to the bacteria and constitutes the raw materials that the microbes will transform into a target chemical.
Right now, many parts of the fermented manufacturing industry still use sugar cane or corn sugars as the microbe feed in their fermentation process. However, the practice of using harvested food crops for industrial purposes is an incredibly wasteful practice that puts pressure on land. It uses up precious, carbon-intensive farming inputs for industry rather than for human consumption.
Synthesis Capital, a major investor in the area, said that the limited amount of sustainable feedstock available for precision fermentation producers was one thing holding back the industry from scaling.
Using sugar cane or corn sugars to feed industrial microbes is not just an environmentally harmful practice. It is also financially costly. Feedstock is often among the biggest operating costs involved in the precision fermentation business. Using virgin food crops leaves fermentation producers vulnerable to the volatility of the agricultural markets – something that they are increasingly sensitive to, as extreme weather from climate change is already making staple harvests more unpredictable.
A small number of companies have adopted more sustainable feedstocks for precision fermentation. These fall into three main groups: food industry waste, forestry waste, and carbon gas.
The most sustainable feedstocks for industrial fermentation
- Food industry waste
Startup Hyfe extracts sugar from wastewater produced by food manufacturing facilities, turning it into a standardised microbe ‘feed’ for precision fermenters to use as an input.
Hyfe’s method of manufacturing this microbe feed doubles as a water treatment system for food processing plants. Hyfe sets up their wastewater processing units on-site next to breweries or canning factories, where they remove all the valuable organic matter from the water and return the purified water to the manufacturer to re-use.
Co-founder Ruiz says that it costs less for food producers to use Hyfe’s water treatment method than other waste management operators, giving “guaranteed” opex savings to their clients.
The food industry covers a broad sweep of waste materials, from the glutinous byproducts of baked goods to mixed organic matter from restaurants.
Other types of food industry waste that have yet to be valorised as microbial feedstock sources are seafood shells and slaughterhouse wastes. These protein-rich byproducts differ from the sugary wastes that Hyfe works with and can be used to manufacture nitrogen-containing compounds like amino acids and amines, which have applications in pharmaceuticals and as food and drink preservatives.
- Forestry waste
Hyfe works with a category of microbial feedstock known as ‘free sugars’. These are readily fermentable sugars, like glucose, meaning they do not require additional treatment steps and to turn into a form that will efficiently feed industrial microbes.
Forestry waste is another potentially cheap and abundant source of microbe sugars. Like the food industry waste streams of Hyfe’s model, they could also offer an alternative to human food crops as feed for industrial microbes.
Lignocellulose is the organic compound that makes barks rigid and contains complex sugars and other biomolecules. However, this wastestream has so far not been easy to commercialise as fermentation feedstock.
Usually, routes to processing lignocellulose for industrial applications start with a pretreatment step called hydrolysis to make fermentable sugars. This adds cost and time to valorising wood waste. Also, the kind of sugars that come from wood can be challenging to use efficiently.
Estonian company Fibenol has managed to develop an economic process for turning hardwood residues into C5 and C6 sugars.
The former are used in producing biofuels while the latter are useful for personal care chemicals, cosmetics, and pharmaceuticals. Fibenol turns these basic sugars into nutrient-rich material that microbes can easily use and further process into biofuels, cosmetics, and pharmaceuticals.
Fibenol began life as a unit within Estonian wood pellet producer Graanul Invest, which wanted to turn its hand to higher value products from the biomass it worked with.
In 2018, it received EU funding for a demo plant and in 2023, its flagship plant became fully functional with an annual capacity of 20, 000 tonnes for cellulosic wood sugars.
In 2023, Fibenol announced a pilot-scale collaboration with biotech startup ÄIO, a startup that develops fermented alternatives to palm oil, coconut oil, and animal fats for use in the food and cosmetics industries.
Under the partnership, ÄIOl is to process Fibenol’s wood-derived sugars under industry-like conditions to make sustainable fats and oils for food and cosmetics. If ÄIO and biomanufacturing companies like it are to scale fermented production, it will rely on companies like Fibenol that offer a reliable flow of microbial feedstock.
- Carbon dioxide
Yes, carbon gas can really be a feedstock in microbial manufacturing. There are certain bacteria, found either in nature or achieved via genetic modification, that absorb the gas from the atmosphere around them, converting them into anything from biomaterials to proteins.
The thought of turning air into solid, bio-based substances can seem counter-intuitive. This is until you realise that carbon atoms are extremely common throughout the biological world. Carbon is easily able to form bonds with other atoms meaning that they are an indispensable component of living cells, including their proteins, nucleic acids (including DNA), carbohydrates, and lipids.
Carbon is a highly sustainable feedstock for industrial microbes as well as having the potential to be the most economical. Apart from being highly abundant, biomanufacturing plants could be designed in such a way that they draw down more carbon than they emit, resulting in industries that offer a net removal of climate-warming carbon from the atmosphere.
Renewables-powered microbial factories that draw on carbon dioxide as feedstock may just be the holy grail of bioeconomy innovations. Co-locating precision fermentation capacity next to bioethanol plants, biogas plants, cement production plants, steel plants, and fossil combustion processes could be an effective way to scale carbon-based forms of biomanufacturing as it would place them next to abundant and largely zero-value industrial carbon emissions.
In 2022, Lanzatech and Danone successfully converted carbon emissions captured from industrial processes into a PET plastic component in a proof-of-concept that they say will need years of development before it hits the general consumer market.
While developments like this are promising, the industry should be wary of becoming a carbon-cleanup tool that fossil-based producers use to justify business models based around petroleum.
One firm already commercialising this method is Colipi, a Hamburg-based startup.
Already the company makes ‘ClimateOil’ – an oil with a ‘minimal’ carbon footprint produced by yeasts fed on carbon dioxide feedstock. The company does not genetically modify their yeasts but bioprospects existing strains by trawling through organic sidestreams.
Colipi’s oil so far has applications in the cosmetics and home care industries. However, the company is now trying to replace harvested palm oil with a microbially-produced substitute for normal vegetable oils.
An alternative to palm oil, a major driver of deforestation in Southeast Asia, has so far been elusive. Yet if Colipi cracks the problem, it will be a breakthrough in demonstrating how carbon-fed microbes could replace environmentally destructive food industry staples.
