The potential of edible and medicinal mushrooms in promoting the circular economy and enhancing food security

Hitoshi Aso CamposGaston Zolla^*

• Laboratorio de Fisiologia Molecular de Plantas, PIPS en Cereales y Granos Nativos, Universidad Nacional Agraria La Molina, Lima, Peru

Globally, more than 3 trillion tons of organic waste are generated yearly from various sources. Thus, over 2 trillion tons of this come from agricultural activities (Millati et al., of their therapeutic properties, although their cultivation is limited. Hericium erinaceus stands as an eminent example, because its secondary metabolites assist with the stimulation of the synthesis of nerve growth factor (NGF), which deficiency is associated with diseases like Alzheimer's and dementia (Thongbai et al., 2015). Ganoderma lucidum is also notable for its triterpenes, such as ganoderic acids, which possess anticancer properties (Ahmad, 2018), and polysaccharides that help lower blood glucose levels (Wachtel-Galor et al., 2011). The polysaccharides PSP and PSK from Trametes versicolor have been shown to possess antitumor properties (Habtemariam, 2020). Another significant medicinal mushroom is Cordyceps militaris, which contains active compounds like cordycepin, structurally similar to adenosine, known to improve physical endurance-beneficial for athletes and older people (Tuli et al., 2014). Finally, it is important to mention that research has been conducted in the study of Psilocybe species within controlled clinical environments for addressing conditions like anxiety and depression (Goldberg et al., 2020). Nonetheless, their use remains strictly regulated and is limited to approved research settings. Every species of mushroom has unique requirements. champignon, therefore, needs a more complex substrate consisting of wheat straw and manure (Sanchez, 2010). Shiitake, on the other hand, has traditionally been cultivated on oak logs, but over time, the use of plastic bags packed with forestry and agricultural waste is more common. Although shiitake mushrooms still require the most extended incubation period-between two and three months in bags and six to twelve months on logs-this modification aids in shortening it (Mata et al., 2020). Furthermore, shiitake mushrooms undergo an important "browning" stage, since the color at this stage has a direct effect on the total yield (Fan et al., 2005).The cultivation of the entomopathogenic fungus Cordyceps militaris has been studied at the pupae and larval levels. However, alternatives have also been explored, with rice being the main ingredient (Shrestha et al., 2012). G. lucidum, H. erinaceus, and T. versicolor are less complex to cultivate, although they prefer hardwood sawdust as a substrate. Furthermore, it is important to maintain optimal conditions for fruiting. For example, (Zhou, 2017) indicates that temperature is crucial during fruiting for G. lucidum, ranging between 25 and 35°C and a relative humidity between 85 and 95%. Meanwhile, for H. erinaceus, the optimal temperature range varies between 10 and 24°C and a relative humidity of 85 and 95% (Sokół et al., 2015). For T. versicolor, there is little literature available on its cultivation, but González Guerrero et al. (2011) indicate that the fruiting temperature varies between 20 and 24°C and with humidity close to 90%.On the other hand, the genus Pleurotus stands out for its ease, speed, and low cost of cultivation (Mandeel et al., 2005). This hardy genus can grow even in unconventional substrates, such as olive oil residues (Dorr et al., 2021). Within the genus, we can find different species that require different temperature ranges for fruiting body formation. For example, P. ostreatus forms basidiocarps between 18 and 22°C; P. Florida from 20 to 28°C; P. citrinopileatus from 18-29°C; P. pulmonarius and P. eryngii from 20-25°C; and P. djamor from 21-30°C (Raman et al., 2021). Thus, P. djamor, P. citrinopileatus, and G. lucidum are more suitable for warmer seasons than H. erinaceus and P. ostreatus, which would be more suitable in colder seasons. Mushrooms are highly versatile and can thrive on various substrates, which allows for the sustainable use of organic waste in agriculture. Thus, Pleurotus ostreatus and Lentinula edodes can be cultivated on straw, seed hulls, corn cobs, sawdust, pulp, and leaves. In addition, Agaricus bisporus and Volvariella volcaea are cultivated on composted organic waste (Grimm and Wösten, 2018;Suwannarach et al., 2022). In urban areas, sawdust can readily be sourced from carpentry shops. However, straw is more challenging and must be transported from rural areas. Therefore, it is crucial to identify suitable organic waste for growing edible mushrooms in cities (Figure 1). Coffee grounds can therefore be added to mushroom substrate (Tambaru et al. 2023). However, because of the density of the substrate, pure coffee grounds do not promote the best mycelium growth. Moreover, pods, stems, and husks are among the other waste materials that can be used as substrates for the growth of mushrooms (Mann and Sooch, 2022). Even grass (Panicum sp. and Pennisetum sp.) from parks and gardens can be utilized to cultivate mushrooms (Liang et al., 2009;Das et al., 2000). The water footprint serves as a standard tool to measure and analyze the water-use efficiency across different production systems (Hoekstra et al., 2011). Mushrooms serve as an alternative protein source because they help lower water footprint values. Smallscale oyster mushroom cultivation in Sri Lanka requires 1,181 liters of water to produce 1 kilogram, according to De Silva et al. ( 2023). This amount is significantly lower than the water needed for other protein sources, such as 1 kg of eggs (3,734 L), broiler chicken meat (7,546 L), pork (9,370 L), beef (15,415 L), soybean meal (1,779 L), and lentils (5,874 L). Additionally, the greenhouse gas emissions from a small mushroom farm in France range from 2.99 to 3.18 kg of CO2 per kilogram of oyster mushrooms (Dorr et al., 2021). In Thailand, the emissions for producing 1 kg of Pleurotus sajor-caju varied among different farm sizes: 3.371 kg for large farms, 5.003 kg for medium farms, and 3.0146 kg for small farms (Ueawiwatsakul et al., 2014). In agreement with these results, Leiva et al. (2015) reported that mushroom cultivation in La Rioja, Spain, produces 4.42 kg of CO2. These findings are significantly lower than those from animal protein sources, particularly beef, since the emissions for 1 kg of beef in feedlots can range between 22 kg (Beauchemin et al., 2010) and 34.3 kg of CO2 (Roy et al., 2012), showing the sustainability of edible mushrooms (Figure 1). Mushroom production and economic value have been increasing globally, and it is expected to rise at a compound annual growth rate of 7.13% during the period 2025-2033, reaching USD 116.26 billion at the end of 2033 (Market Data Forecast, 2025). Moreover, mushroom cultivation plays a crucial role in rural development in China because it can alleviate poverty, generating incomes up to ten times higher (Figure 1) than traditional crops like rice and corn (Li and Xu, 2022), because of the limited space requirements, short period (Imtiaj and Rahman, 2008), and the ability to grow vertically (Kaur and Kapoor, 2023). This success has stimulated countries like India to launch training programs for young people and women to cultivate mushrooms (Thakur, 2020), resulting in a production increase of approximately 0.13 million tons between 2010 and 2017 (Raman et al., 2018). In Africa, Motlhalamme (2019) found that cultivating Pleurotus mushrooms using residues like millet could yield an average income of $7,406.50 per hectare, compared to just $16.87 per hectare from millet grain. Similar results are reported in the Democratic Republic of the Congo. Thus, Kazige et al. (2022) highlighted that using plantain leaves for Pleurotus cultivation could generate a profit of up to $4,166.70 per hectare, with production costs of $1,960 per hectare. Mushroom breeding encounters global challenges that affect food security, productivity, accessibility, and nutritional quality. Native fungal biodiversity presents a valuable opportunity to enhance breeding and introduce new species. Some countries, like Mexico and Korea, have already utilized native strains to improve strains and increase commercial value (Sobal et al., 2007;Jang et al., 2016). Moreover, it is important to know the underlying genetic mechanism that controls high yield to accelerate mushroom breeding and cultivation (Figure 1). Therefore, it is critical to identify genes controlling mycelial growth, primordium formation, button germination, and fruiting body development (Wang et al. 2024). Improvements have been made; thus, the study of Li et al. (2023) found that the Cmhyd4 gene negatively regulates fruiting body development in Cordyceps militaris, and its knock-out increased the density of fruiting bodies by 20% to 30%. Additionally, CRISPR-Cas9 technology can modify genes to improve these characteristics. It works well in edible mushrooms like Pleurotus, where Boontawon et al. (2021) created mutants that are resistant to harmful substances like 5-fluorouracil. Moreover, Liu et al. (2020) used an improved CRISPR/Cas9 system to facilitate functional genomic studies in Ganoderma lucidum. The increasing demand for edible and medicinal mushrooms is driven by their minimal carbon and water footprint which contributes to community well-being preserves the environment, and promotes food security, is making their cultivation a sustainable solution that can help transform waste from urban and rural areas into several products, such as fresh food, bakery products, noodles, and soups fortified with mushrooms, as well as extracts, and tinctures. Therefore, it is critical to recognize and incorporate fungal diversity into locally tailored production systems that also protect existing ecosystems, especially in countries with high fungal biodiversity. Finally, CRISPR/Cas9 technology can play a critical role in developing the high-yielding mushroom strains required for the industry.