GUEST AUTHOR: Tomas Linder, PhD | Associate professor | Department of Molecular Sciences | Swedish University of Agricultural Sciences | Tomas Linder on Facebook
These days it is hard to escape the buzz surrounding so-called cultured meat (also known as artificial meat, cell-based meat, in vitro meat, lab-grown meat, “cellular agriculture” – the list goes on and on). In recent years I have noticed that many news stories about cultured meat make either explicit or implicit claims about the potential of cultured meat to transform global food production by decreasing the environmental impact of meat production and/or increasing global food production capacity. Examples includeCNN,BBC,the Guardian,Newsweek,Forbes,Quartz andDeutsche Welle.
I would imagine that to many lay readers/viewers out there, it would seem like cultured meat will be one of the best technology options for future sustainable food production. Since you also affect public policy as voters and consumers, it is absolutely essential that you understand what the pros and cons of cultured meat are. I will defer toothers regarding the question of whether the carbon footprint of cultured meat is smaller or greater than that of conventional meat. Instead, I want to address the misconception that cultured meat somehow will have the capacity to “feed all of humanity” in the near future.
I want to make it clear from the beginning that I don’t have anything against the idea of cultured meat itself. As a graduate student, I cultured mammalian cells in dishes for a number of years and the technology is not scary or repugnant to me. So if people want to eat cultured meat, go for it! I also think that the ethical aspect of cultured meat is perfectly sound. It is, after all, a technology that allows people to continue eating meat without having to sacrifice the welfare and lives of innocent animals.
Cultured meat also has some additional benefits apart from the animal welfare issue. Because the cultivation of muscle cells takes place in advanced bioreactors with precise control of temperature, nutrient supply, air circulation etc., the production of cultured meat is independent of external environmental conditions. That means that you could produce cultured meat anywhere on the planet as long as there is a supply of energy, water, air, and nutrients.
However, it is precisely these requirements for advanced bioreactors and an external source of nutrients that is the reason I predict that cultured meat will only play a marginal role in future food production. I will address the issue of nutrients first because that is the most important one.
My beef with cultured meat
The simple reason why cultured meat will never “feed humanity” is because animal cells can only grow if they are supplied with carbohydrates, protein, and fats. All three groups of compounds can only come from another living organism, which means that you need to produce “feed” for cultured animal cells just like you would have to do for any domesticated animal. Also keep in mind that when you feed animal cells with these three macronutrients, a portion of the macronutrients will be used as metabolic fuel by the cells through the process ofcellular respiration, which converts them to carbon dioxide. So that begs the question of why you would feed animal cells for subsequent human consumption instead of just using those same resources to produce plant-based food for direct human consumption.
Proponents of cultured meat would probably argue that the so-called “feed conversion ratio” is much better for cultured meat than the animal itself. Feed conversion ratio (FCR) is a measure of how efficiently a production animal converts its own food into biomass for human consumption in the form of meat, milk or eggs. There are different ways that FCR can be expressed. One measure of FCR is the protein conversion efficiency i.e. the proportion of protein fed to a production animal that is retained for human consumption. For example, a broiler chicken typically has a protein conversion efficiency of20 % while beef cattle at slaughter will only have retained around4 % of the protein that they have been fed from birth. An animal with poorer FCR will, therefore, require more feed (and therefore more arable land) to produce the same amount of meat (or milk) as an animal with better FCR. A 2017study in the journal Global Food Security found that the FCR of cultured meat did not offer substantial benefits compared to poultry meat or eggs when expressed as the amount of land required per weight of animal protein. So even if the FCR for cultured beef may be better than raising beef cattle, the same does not appear to be true for cultured poultry meat versus raising broiler chickens.
No matter how you slice it, more edible biomass in the form of feed will always be consumed than is eventually produced as cultured meat. Or to put that in another way: if your output is always smaller than your input, why not just eat the input? This is significant because our current global food production capacity is ultimately limited by the rate at which CO2 is converted to edible biomass through photosynthesis. That means that there is afinite allowance of biomass being produced per unit time that can be used for food production. It would, therefore, seem wasteful to produce cultured meat rather than produce edible plant biomass for direct human consumption. So if your main concern as a consumer is the environment, then switching to a vegetarian or vegan diet (including plant-based meat products) would make a lot more sense than simply substituting real meat for cultured meat.
A role for herbivores
Reducing the consumption of animal meat – especially beef, would be one of the most simple and effective ways to ensure that there will be enough food for the global population of the future. However, cattle and other domesticated herbivorous mammals like goats, sheep, camels, water buffaloes, llamas, yaks, and caribou can still play a significant role in future food production. The reason for this is that there is one very important thing that a cow can do, which no muscle cell growing in a petri dish or bioreactor will ever accomplish. A cow can digestcellulose-containing plant tissues (i.e. grass and leaves) and convert them into muscle tissue and milk.
Cellulose is the most common biological compound on the planet. Although the cellulose molecule is a simple chain of glucose molecules, the particular way those glucose molecules are connected end-to-end makes the cellulose molecule highly resistant to digestion. The way that cattle and otherruminants digest cellulose is by enlisting billions upon billions of microorganisms that reside inspecial compartments of the ruminant foregut. These microorganisms, in turn, secrete a battery of different enzymes that break up the cellulose chains into progressively shorter and more digestible fragments. The ability of ruminants and other domesticated herbivores to digest cellulose, therefore, makes it possible to produce food in environments that cannot be converted to cropland because of poor soil quality, harsh climate conditions or because the terrain is simply too hilly to be able to sow and harvest a crop.
Nature’s own low-tech bioreactors
The other problem with cultured meat is its requirement for advanced (i.e. expensive) bioreactors for large-scale production. A significant portion of the human population still lives in developing economies where subsistence farming is the predominant form of food production. Such countries lack the capital required to build the facilities for cultivating animal cells as well as the infrastructure to distribute the resulting product among their populations. In addition, the weak purchasing power of these populations makes it unlikely that the average citizen will be able to afford the finished food product.
Domesticated herbivores, on the other hand, are well suited for high-quality protein production in developing economies, especially in regions where local soils can’t support high-capacity crop production. (It should also be noted that in many developing economies, domesticated herbivores play very important roles as work animals for the tilling of fields, transporting people and goods, etc.) In essence, livestock are low-tech, mobile and self-replicating bioreactors for the production of meat, milk, wool and leather. All you need to do is provide the animal with food (grass or leaves), water and shelter. In the end, the extent to which cattle and other domesticated herbivores should be employed for the production of meat and milk on a global scale becomes a trade-off between the environmental costs (effects of overgrazing, methane emissions, etc.) versus the ability to utilize otherwise low-yielding land areas for food production.
The case for mycoprotein
Finally, I would like to contrast cultured meat with the meat imitation productmycoprotein to see whether mycoprotein has a better shot at “feeding humanity”. The mycoprotein ingredient in Quorn-brand products is made from a filamentous soil fungus called Fusarium venenatum. At theQuorn factory in northern England, F. venenatum is cultivated in 40-meter tall bioreactors that can churn out 60 metric tons of mycoprotein per day. The current process uses glucose syrup as the main source of metabolic carbon for fungal growth. Just like with cultured animal cells, a proportion of that sugar will be used by the growing fungus for energy generation and therefore the final product will always contain less edible biomass than went into making it. That means that you will still need to grow corn, sugar cane or sugar beets in order to feed the mycoprotein fungus.
Quorn factory – Getty Images
So in its current configuration, the mycoprotein production process stands no greater chance of feeding humanity than cultured meat. But notice that I said, “in its current configuration”. As it happens, F. venenatum and most other microorganisms are not limited to carbohydrates, protein, and fats for growth. For example, it is entirely possible to grow F. venenatum on a simple mixture of acetic acid and ammonia along with some salts and trace minerals. This particular ability of F. venenatum is very significant since it is also possible tochemically synthesize acetic acid directly from CO2. Mycoprotein could, therefore, be produced without any requirement for photosynthesis and hence there is no requirement for arable land either. In fact, by using CO2-derived acetic acid as a growth substrate, the production of mycoprotein could be completelydecoupled from the conventional biophysical constraints of food production.
The possibility of producing mycoprotein from CO2-derived acetic acid looks great on paper but of course, there are many other real-world aspects that need to be factored in. Just like with cultured meat, the production of mycoprotein requires big, expensive bioreactors, which precludes their deployment within developing economies for the immediate future. Truly large-scale production of mycoprotein would require thousands of giant bioreactors, which entails large embedded CO2 emissions because of the significant quantities of concrete and steel that would be needed for bioreactor construction. On top of that there is also the energy that would be needed in order to capture and extract CO2 from the atmosphere followed by its conversion it to acetic acid.
Quorn’s Belasis bioreactor factory (Photo courtesy of Quorn)
Final ruminations on what’s at “steak”
Ultimately there are no free lunches in the global food production system. It is obvious that humanity must make fundamental, structural changes to both how we produce and consume food. Although I am clearly a proponent ofmicrobial sources of food and feed, I do not believe that there is a single solution to our current predicament. At the same time, I think it is very important that we clearly understand the basic biophysical properties and constraints of the global food production system. As I see it, cultured meat does not address the issues of global food security or sustainable intensification. Rather the chief purpose of cultured meat is to satisfy customer demand for a meat product that does not involve the killing of animals. And that in itself is a noble pursuit worthy of investment.
Tomas Linder is an associate professor of microbiology based at the Swedish University of Agricultural Sciences in Uppsala, Sweden. He studies microbial metabolism and how it can be applied for food production, pest control and degradation of environmental pollutants.
GUEST AUTHOR: Tomas Linder, PhD | Associate professor | Department of Molecular Sciences | Swedish University of Agricultural Sciences | Tomas Linder on Facebook
