Environmental impacts
Land use
The land use impact of microbial fermentation depends principally on feedstocks. Just like meat production, some microbial fermentation relies on crops. Glucose from refined maize or sugar cane is used to feed the organisms that ferment, whether they are bacteria or fungi.
Nonetheless, land use for growing mycoprotein is lower than beef or chicken meat production,[1] and land use for growing dairy alternatives is less than conventional dairy.[2] Land use for feedstocks of microbial fermentation could decrease even further in the future as other feedstocks are considered.[3]
Microbial fermentation can also rely partially or completely on gas as feedstock (e.g. CO2), which results in only minimal land use.
Water use
The evidence on the use of freshwater for microbial fermentation suggests that it is significant, although the literature shows a wide range of estimates, which are sometimes higher, equivalent to, or lower than water use for conventional proteins.[4]
Greenhouse gas (GHG) emissions
Emissions associated with fermentation are largely caused by feedstocks. Most production relies on either refined sugars from crops (maize or sugarcane) or gas (generally nitrogen). Gases used as feedstocks are themselves produced through a very energy intensive process that consumes large quantities of fossil fuels and emits high levels of CO2.[5]
The evidence indicates that GHG emissions of mycoproteins productions are lower than those of chicken and significantly lower than those of beef[6], while those of dairy alternatives are lower to significantly lower than those of conventional dairy proteins.[7]
Waste
The production of single-cell proteins via fermentation has been identified as a solution for recycling waste from other processes, particularly those from conventional agriculture.[8] There is little evidence available on waste generated from microbial fermentation, apart from wastewater, which was explored in a case study.[9]
In recombinant protein (e.g. milk proteins) production processes using microbial fermentation, the left over microbial biomass is potentially a waste product. As the microbes are genetically modified, the microbial biomass cannot be used as food or feed in the EU countries.[10]
[1] Parodi et al. 2018.
[2] Tuomisto HL, 2022, Diaz-Bustamante et al, 2023.
[3] E.g. Upcraft T et al., ‘Protein from renewable resources: mycoprotein production from agricultural residues’, Green Chemistry 23(14): 5150-5165, 2021.
[4] Diaz-Bustamante et al., 2023; Smetana et al., 2023, Tuomisto 2022, Behm et al., 2022.
[5] https://cen.acs.org/environment/green-chemistry/Industrial-ammonia-production-emits-CO2/97/i24; also Järviö N, Netta-Leena M, Kobayashi Y, Ryynänen T, Tuomisto HL, ‘An attributional life cycle assessment of microbial protein production: A case study on using hydorgen-oxidizing bacteria’, Science of the Total Environment, 2021, 776, 145764, https://doi.org/10.1016/j.scitotenv.2021.145764.
[6] Hadi and Brightwell 2021.
[7] Diaz-Bustamante et al., 2023;, Behm et al .,2022.
[8] Onyeaka H et al., ‘Single Cell Protein for Foods and Feeds: A Review of Trends’, The Open Microbiology Journal, 16, 2022.
[9] Järviö N et al., ‘An attributional life cycle assessment fo microbial protein production: A case study on using hydrogen-oxidizing bacteria’, Science of the Total Environment, 776, 145764, https://doi.org/10.1016/j.scitotenv.2021.145764.
[10] Behm et al 2022.