The food system is currently evolving towards a state that involves a widespread second domestication, which employs the large-scale cultivation of microorganisms and tissues for food applications (RethinkX, 2019). This is the next step in the creation of a human-centric food system that started from the capture of animals (pre-domestication), followed by the first domestication period that involved the ‘cultivation’ of macroorganisms (i.e., mainly animals). The use of microorganisms to transform foods has been used by humans for >10,000 years, but only within the 20th century more targeted approaches have been developed (Liu et al., 2018). Recently there has been increased interest in cultivating microorganisms and tissues to generate foods or food ingredients, which may allow for the production of more sustainable food products without the domestication of animals and plants (Eibl et al., 2021; Grossmann and Weiss, 2021). Broadly these efforts can be summarized under the term ‘cellular agriculture’, which consists of three main pillars: (i) tissue engineering, (ii) precision fermentation, and (iii) microbial biomass fermentation.

Tissue engineering is used to obtain plant and animal tissue through in-vitro approaches. The most prominent tissue engineering endeavor is the production of cultivated meat (Ben-Arye and Levenberg, 2019). Precision fermentation – i.e., the production of recombinant proteins – has been utilized for foods since the 1980s, which resulted in the release of chymosin as the first FDA (USA) food-approved recombinant protein in 1990 (Sutay Kocabaş et al., 2022). This technology has recently been expanded to other types of proteins such as β-lactoglobulin or ovalbumin (Aro et al., 2023; Hoppenreijs et al., 2024). Food products containing these recombinant proteins have also been released to the market, for example, by Bored Cow (New York, USA) or Remilk (Rehovot, Israel) (Wrobel, 2023). Lastly, microbial biomass fermentation involves the production of cells (typically algae, fungi, and bacteria) for direct use in foods as a whole cell ingredient or as a raw material to extract certain ingredients (lipids, proteins, pigments, etc.) (Buecker et al., 2022; Grossmann et al., 2019). These ingredients are sometimes also referred to as single-cell proteins. Quorn (Stokesley, UK), Solar Foods (Helsinki, Finland), and Nature's Fynd (Chicago, USA) are examples of companies that use this approach.

The main idea of these cellular agriculture cultivation techniques is to establish food value chains that are less dependent on conventional agriculture. However, all of them require growth media that rely on agricultural, chemical, and mining supply chains. Especially tissue engineering requires sophisticated growth media that often rely on animal-based ingredients such as fetal bovine serum that is obtained through ethically questionable methods (Lee et al., 2022a). The are currently tremendous efforts underway to replace such ingredients in tissue engineering, which will not be discussed in this review because of the large number of literature available regarding this topic (Hubalek et al., 2022; Lee et al., 2022a; Lee et al., 2023; O'Neill et al., 2021).

Biomass and precision fermentation media rely on three main ingredients that are derived from agricultural, chemical, and mining feedstocks: (i) fermentable sugars (usually monosaccharides such as glucose and/or disaccharides such as sucrose), (ii) a nitrogen (ammonium, urea, etc.), and (iii) a phosphorus source (i.e., phosphates). These ingredients are mixed at optimum ratios to obtain high growth rates and/or maximum yield of the desired compound (Gao et al., 2007; Wikandari et al., 2023) First, fermentable sugars are derived from starch and sugar-containing crops such as wheat, corn, or sugarcane. The starch is hydrolyzed to glucose, which is then used to formulate the media (Blanco et al., 2020; Kunamneni and Singh, 2005). This requires agricultural land that could also be used for other purposes if such fermentable sugars were derived from other types of raw materials. The production of non-starch-derived fermentable sugars (2nd generation sugars) for generating bioethanol has received a lot of attention, but alternative fermentable sugar feedstocks for food biotechnology have received only a little attention (Robak and Balcerek, 2020). Second, nitrogen-containing media ingredients are typically a product of the Haber-Bosch process that currently runs on fossil fuels, which yields ammonia utilizing natural gas as one of the main ingredients (Smith et al., 2020). It is estimated that this process uses 1–2% of total global energy, 3–5% of the globally produced natural gas, and is responsible for 1–3% of the total CO2 emissions (Kyriakou et al., 2020; Soloveichik, 2019; Song et al., 2023). Thus, sustainable alternatives are required to minimize the emissions of large-scale cellular agriculture production systems. Lastly, phosphorous is a finite resource, which will be depleted eventually. A comprehensive approach to re-use and recycle phosphates, therefore, needs to be implemented in biomass and precision fermentation.

This review discusses sustainable feedstocks and production processes to obtain fermentable sugars, nitrogen compounds, and phosphates that can be deployed in biomass and precision fermentation media. The individual technologies and emissions as well as other important considerations are summarized in Table 1. Using these alternative ingredients will ultimately lower the land use and emissions associated with culture media formulation.