# Emerging Trends in Sustainable Biological Resources and Bioeconomy for Food Production
## 5 Common Resources in Green and Blue Bioeconomy  
### Fermented Proteins  
Microbial fermentation is a sustainable method of producing high-quality protein for food systems. Fermented proteins, also referred to as single-cell proteins (SCP), are defined as the protein-rich biomass derived from microbes such as filamentous fungi, yeast, and bacteria cultivated in controlled environments [72]. These microbes have the capacity to convert a variety of feedstocks, ranging from sugars to agricultural residues and even gases, into edible biomass, thereby presenting a promising alternative to conventional animal proteins. In the context of escalating global protein demand, SCP offers a strategy to \"decouple\" protein production from land and water constraints, thereby reducing the environmental impact of food production [73]. Fermentation-based protein production is typically rapid and efficient, yielding biomass in a matter of hours or days, in contrast to the months or years required for plant and animal proteins. This efficiency is reflected in a significant reduction in resource consumption and greenhouse gas emissions. For instance,the carbon footprint of fungal mycoprotein has been documented as being ten times lower than that of beef and four times lower than that of chicken [74]. Furthermore, its lifecycle greenhouse emissions per kilogram are even lower than those of soy or pea protein [75]. Such reductions in emissions and land use underscore the sustainability advantages of fermented microbial proteins over traditional protein sources. Fermented proteins are known to offer favorable nutritional properties. Filamentous fungi have been found to produce biomass with 30-50% protein (dry weight) and an amino acid profile that adheres closely to the standards set out by the Food and Agriculture Organization (FAO), with notable richness in lysine and threonine [72]. Fungal mycoprotein, produced from _Fusarium venenatum_ in continuous fermenters, has been shown to be high in protein and to naturally contain approximately 25% dietary fiber (largely \(\beta\)-glucans and chitin from cell walls), in addition to micronutrients such as B-vitamins, selenium, and zinc [76]. Indeed, the Quorm(tm) mycoprotein product has been consumed in over eight billion meals since its 1985 launch, attesting to its commercial success and consumer acceptance. A plethora of studies have indicated the potential health benefits of fungal protein, suggesting its functionality as a prebiotic fiber, its ability to assist in the regulation of blood cholesterol and glucose levels, and its capacity to support muscle protein synthesis. Yeast-derived proteins have similarly high protein content (often \(\sim\)40-55%) and are rich in B-vitamins. Yeast biomass and extracts (e.g., nutritional yeast) are already used to fortify foods or impart savory flavors. Bacterial SCP has been found to contain elevated levels of protein (50-80%), exhibiting favorable amino acid profiles. However, the high nucleic acid content (RNA) of these samples frequently necessitates processing to avert the occurrence of purine overload [76]. It is noteworthy that certain bacterial fermentations yield valuable co-products. For instance, many bacteria and yeast synthesize vitamins or antioxidants along with protein, thereby enhancing the nutritional profile of biomass. It is evident that fermented microbial proteins have the capacity to supply essential amino acids that are comparable to those derived from traditional animal sources. This renders them a potentially viable option for both human nutrition and food security. A significant motivator for the exploration of fermented proteins is their capacity to reduce the environmental impact. The cultivation of microbes in bioreactors necessitates a significantly reduced land area in comparison to the raising of crops or livestock. Furthermore, these bioreactors can be utilized in non-arable locations.