A mushroom is the fruit body of a fungus. There are 44,000 known species in the fungi kingdom, but not all of them produce mushrooms. Fungi lack chlorophyll and are heterotrophic organisms that break down organic matter in various ways. Mushrooms have always been an important source of food, with high nutritional value and medicinal attributes. With the use of biotechnological applications, mushrooms have gained further attention as a source of healthy food and bioenergy. Mushroom biotechnology is defined as the science in which mushrooms are included in processes like bioconversion, biorefining, bioremediation, and biodegradation.
1. Introduction
Mushroom biotechnology is defined as the science in which mushrooms are included in processes like bioconversion, biorefining, bioremediation, and biodegradation (Figure 1). Negative and positive issues can arise from the relationship between mushrooms and WEF (Figure 1). Biotechnology might guarantee the quality and security of WEF and thus contribute to combatting infectious diseases, reducing hunger, and remediating environmental degradation. The main problems within this relationship are represented by the production of biological weapons and security/safety problems at the global level of WEF.
Figure 1. The role of mushroom biotechnology on the water–energy–food nexus, including the positive (pros in black color) and negative (cons in red color) aspects that may be generated due to different applications of biotechnology through certain processes, including bioconversion, biorefinery, bioremediation, and biodegradation.
The many biotechnological applications of mushrooms have generated great attention aimed at the growing demand for energy, food, fodder, and fertilizers
[1][2][3]. Biotechnological applications of mushrooms are considered an emerging approach for utilizing WEF resources.
2. Mushrooms to Produce Nanoparticles
Myco- or green biosynthesis of eco-friendly nanoparticles (NPs) is one of the most important recent applications of mushrooms. This biological method for producing NPs is preferable compared to chemical or physical methods to avoid environmental pollution. NPs have great applications in the fields of water, energy, and food, including enormous benefits in water purification/remediation
[4], producing high-efficiency energy and its storage
[5] and food security
[6]. In this section, different applications of NPs in the fields of food and energy will be focused on, whereas water will be discussed in the next section. Nanoparticles produced by mushrooms have several applications in the food and human health sectors, as tabulated in
Table 1. Silver nanoparticles are the most common among NPs, which can be produced using the mushroom
Laxitextum bicolor for myco-synthesis, as reported by
[7].
Mushrooms can produce NPs through two different methods: (1) production inside the mycelium cells stimulated by intracellular enzymes or (2) production outside these cells by extracellular enzymes
[8][9][10]. The myco-synthesis of NPs can be performed by certain steps. Myco-synthesis can produce gold (Au-NPs), silver (Ag-NPs), selenium (Se-NPs), magnesium oxide (MgO-NPs), titanium oxide (TiO
2-NPs), copper oxide (CuO-NPs), zinc oxide (ZnO-NPs), and cadmium sulfide (CdS-NPs) NPs
[11]. Silver NPs are very common and can be generated using many mushroom species (
Agaricus bisporus,
Amanita muscaria,
Pleurotus ostreatus,
Ganoderma applanatum, etc.). Ag-NPs have been utilized for their antibacterial, anticancer, antioxidant, and antimicrobial activities
[11].
Table 1. Selected studies on the biosynthesis of nanoparticles (NPs) by mushrooms and their suggested applications related to water, energy, food, and human health.
Mushroom Species |
Nanoparticles (NPs) |
The Application |
References |
Enoki mushroom (Flammulina velutipes) |
Ag-NPs (~10 nm) |
Biodegradable natural biopolymers as active food packaging films. |
[12] |
Oyster mushroom (Pleurotus florida) |
Ag-NPs (~12.62 nm) |
Effective antimicrobial agents as an alternative to traditional antibiotics to control diseases/microbial infection. |
[13] |
Reishi mushroom (Ganoderma lucidum) |
Ag-NPs (15–22 nm) |
Ag-NPs can be applied in the pharmaceutical, medical, and cosmetic fields due to their antioxidant, antibacterial, and antifungal activity. |
[14] |
Oyster mushroom (Pleurotus florida) |
Gold-platinum (Au-Pt-NPs, 16 nm) |
Au-Pt-NPs showed anticancer activity against human colon cancer. |
[15] |
Pleurotus giganteus |
Ag-NPs (2–20 nm) |
Ag-NPs have antibacterial and α-amylase inhibitory activity. |
[16] |
Macrolepiota procera |
Ag-NPs (20–50 nm) |
Ag-NPs have antibacterial activity as a green corrosive inhibitor for mild steel in cooling tower water systems. |
[17] |
Termitomyces heimii mushroom |
CdS-NPs (<5 nm) |
CdS-NPs have potential use in energy (solar panels), biomedical, biofilm, drug delivery, and environmental applications. |
[18] |
Cordyceps militaris mushroom |
ZnO-NPs (1.83 nm) |
ZnO-NPs can be used for the development of therapeutic drugs and have antioxidant, antidiabetic, and antibacterial activity. |
[19] |
Inonotus hispidus mushroom |
Ag-NPs (69.24 nm) |
Ag-NPs exhibited activity against different pathogenic bacteria and fungi, showing antimicrobial potential. |
[20] |
Ramaria botrytis mushroom |
Ag-Au bimetallic composite NPs |
The nano-composite was effective for intensive industrial and biomedical applications due to powerful antioxidant properties for DPPH radical scavenging. |
[21] |
Shiitake mushroom (Lentinula edodes) |
ZnO-NPs (21–25 nm) |
ZnO-NPs degraded methylene blue dye pollution by 90% within 135 min in wastewater. It also showed promise as an antibacterial product. |
[22] |
Portabello mushroom (A. bisporus) |
Au-NPs (53 nm) |
Au-NPs reduced methylene blue by about 98% in wastewater and decolorized azo dye. |
[23] |
Ganoderma lucidum |
ZnO-NPs (using 25 mL for extraction) |
ZnO-NPs were used in vitro as nanofertilizer for feeding garden cress (Lepidium sativum). |
[24] |
Edible mushroom (A. bisporus) |
Ag-NPs (average 17 nm) |
Myco-fabricated Ag-NP had antioxidant/antimicrobial effects without any cytotoxic impacts on human dermal fibroblast cells. |
[25] |
A proposed mechanism for forming NPs from mushrooms has been discussed in many previous publications using different types of enzymes (mainly reductases), intracellular or extracellular, for reducing and stabilizing NPs through the mushroom exudates of biomolecules
[26][27][28]. Mushroom hypha cells can secrete exudates as extracellular enzymes and reduce the oxidation state of metal ions, creating elemental forms of these metals through secondary metabolites such as alkaloids, cyclosporine, griseofulvin, flavonoids, lovastatin, polysaccharides, mevastatin, and saponins
[11]. The intracellular enzymes work in the mushroom hypha cells in the presence of enzymes such ACCases (Acetyl-CoA carboxylase), nicotinamide adenine dinucleotide (NADH), NADH-dependent nitrate reductase enzymes, and peroxidases, which can reduce metallic ions into reduced metallic elemental forms (M
0), creating NPs. In both intra- and extra-cellular methods, NPs should be purified to eliminate any remaining fungal by-products through simple filtration and then centrifuging or chemical washing
[9].
3. Mushrooms for Bioremediation
Soil and water pollution resulting from rapid industrialization, the intensive use of agrochemicals, including mineral fertilizers and pesticides, urbanization, and other anthropogenic activities is a serious global problem. Using plants to remove pollutants or combining plants and microbes in phytoremediation has been known for the last several decades, whereas myco-remediation has gained recent attention. Such remediation depends on certain enzymes that the mushrooms can produce and that can be used in the degradation of organic pollutants
[29]. Myco-remediation can also be accomplished by applying spent mushroom substrate (SMS) as a by-product after mushroom cultivation. This has many advantages, including its eco-friendly nature and low cost (
Table 2)
[30]. The potential of myco-remediation can be increased by integration with nanomaterials, leading to the nano-restoration of polluted soil and water
[31][32]. Many recent studies confirmed that mushroom remediation is a sustainable and promising approach for the biodegradation of persistent pollutants in soil and wastewater treatments through the production of enzymes such as peroxidase and laccase (e.g.,
[29][32]).
Table 2. Selected studies on mushroom remediation of polluted soil and water using spent mushroom substrate (SMS).
Mushroom Species |
Polluted Medium |
Main Finding of the Application |
Reference |
SMS from Pleurotus eryngii and A. bisporus |
Cd-polluted paddy soil (total Cd, 72.87 mg kg−1) |
Applied SMS improved the biomass of root and straw at different growth stages by reducing the uptake of Cd and accumulation in rice parts. |
[33] |
SMW of Pleurotus ostreatus |
Anionic dyes with initial dose of 100–1300 mg g−1 |
Max. adsorption capacities of SMW were found to be 15.46, 18, 14.62, and 20.19 mg g−1 for DB22, DR5B, RB5, and DB71, respectively. |
[34] |
Spent mushroom substrate compost (SMSC) or biochar (SMSB) |
Added 0.6, 1.2, 1.8, and 2.4 mg kg−1 Cd to soil |
About 4% SMS can be used for amending Cd-polluted soils by Cd immobilization and improving chemical and biological soil properties. |
[35] |
SMS from Pleurotus ostreatus |
Soil contained 8.535 SMS, and its applied rate was 20–40 mg kg−1 |
Optimum applied into the SMS is 8.86–9.51 g kg−1 soil when growing pak choi (Brassica chinensis L.). |
[36] |
SMS of Pleurotus ostreatus |
Wastewater polluted with sulfonamides |
Up to 83–91% of sulfonamides were removed over 14 days sulfamethoxazole, sulfathiazole, sulfadiazine, sulfapyridine, etc. |
[37] |
Spent mushroom substrate |
Constructed wetland with simulated acid mine drainage |
Removal rate of metal-burdened wastewater by SMS was Al, Zn, Cu (99%), Fe (97%), and Pb (97%) over a period of 800 days. |
[38] |
Spent mushroom substrate 0.5% (w/w) |
Cd polluted soil, level at 0.6 mg kg−1 |
Applied SMS and biochar was more efficient than lime in reducing Cd content and increasing organic matter and enzyme activity after 4 weeks. |
[39] |
Spent mushroom substrate |
Soil contaminated with carbendazim |
SMS applied to fungicide-polluted soil reduced soil carbendazim residues and significantly increased the total-N, OM, and microbial biomass in the soil. |
[40] |
Substrates of Enoki,A. bisporus, and Auricularia auricula (AAR) |
Soil polluted with chemical fertilizer |
AAR recorded the highest level of soil nutrients among the 3 SMS replacements (mineral fertilizer by 25%); reduced heavy metals contamination. |
[41] |
Spent mushroom substrate and its biochar |
Cd polluted soil, level at 0.6 mg kg−1 |
Applied SMS and its biochar alleviated the adverse effects of Cd and N and increased pH, CEC, and OM content in the soil. |
[42] |
4. Mushrooms to Produce Bioenergy
Due to its nutritional value and functional bioactivities, the direct product of mushroom cultivation is healthy food. This builds global market value and has led to steady growth in the mushroom industry
[43]. Due to the ability of recycling and utilizing mushroom residues, the cultivation of mushroom is considered an excellent biotechnological process (
Figure 2). After harvesting mushrooms, a huge amount of waste (spent mushroom substrate; SMS) remains. It is urgent that these wastes be managed in a sustainable way that protects the environment. Based on the concept of waste-to-fuel, one management option for SMS lignocellulosic wastes is to use it as a feedstock to produce biofuels, including bioethanol, biogas, bio-H
2, bio-oil, and solid biofuels
[43]. Therefore, integrated mushroom cultivation for food and biofuel production can simultaneously meet rapidly rising global demands for both energy and food
[43]. The cultivation of mushrooms can serve as an efficient biological pretreatment for producing biofuel and promoting its yield, improving the overall economy and supporting the biorefinery approach
[44].
Figure 2. It is important to move towards zero (0) waste from food production and processing, and the mushroom industry can help with this. General food wastes are presented in (A), whereas the generation of agro-industry residues are in (B). The cultivation of mushrooms is an important source of healthy food (C). At the same time, producing only 1 kg of fresh mushroom may generate about 5 kg of wet byproducts, or spent mushroom substrate (SMS). Thus, this waste needs to be managed through the biorefinery or circular bioeconomic approach (D).
There are increasing concerns within the mushroom industry about the accumulation of SMS. If SMS waste is not properly managed, this may have an adverse impact on the environment, economy, and human health. Therefore, there is an urgent need for an effective strategy for the proper management of SMS by recycling and reutilization. Several studies focused on this, and six examples are provided here: (1) Study the valorization of SMS for producing low-carbon biofuel viewed through the circular economy of utilizing and recycling SMS as renewable feedstock to produce biogas, biohydrogen, bioethanol, bio-oil, and solid biofuels
[43]. (2) Assess optimal conditions to increase the yield of biogas from SMS using the hydrothermal pretreatment (HTP) method to improve the biodegradability of the SMS by 87% compared to mechanically pretreated biodegradability of 61%
[45]. (3) Combine SMS with sewage sludge (SS) to convert SS into renewable fuels and N-rich liquid fertilizers through hydrothermal carbonization while also significantly improving fuel and fertilizer quality
[46]. (4) Apart from producing bioenergy, SMS can be used to produce compost through the enzyme activity of polyphenol oxidase, carboxymethyl cellulase, catalase, and laccase, with are correlated with the composition of the microbial community
[47]. (5) Applying liquid organic fertilizer formed from anaerobic fermentation of liquid SMS enhanced pak choi production by around 30% and improved the level of nutrients in the studied soil due to the synthesized hormone indole-3-acetic acid, IAA
[48]. (6) SMS extract efficiently protected the active components of
Bacillus thuringiensis (Bt) from UV irradiation by forming lignin and lignin–carbohydrate complexes, which possessed the ability to scavenge reactive oxygen species (ROS), had a high UV-screening effect, and improved the UV stability of Bt formulation
[49].
5. Mushrooms to Produce Bioactives
Mushrooms are rich in pharmaceutical and nutritional compounds. These bioactives have a variety of clinical applications and many therapeutic attributes because of their qualities as antioxidants, as well as anticancer, antimicrobial, antidiabetic, anti-inflammatory, and prebiotic activities
[50]. Several recent studies on mushroom bioactives discussed the compounds found in different groups of mushrooms (
Table 3) and confirmed the benefits of edible/medicinal mushroom as a source of healthy food
[51]. Kour et al.
[52] reported on the nutraceuticals found in mushrooms and their benefits as food due to their content of bioactives, such as polysaccharides protein complexes, polysaccharides, peptides, terpenoids, and phenolic compounds. The immunomodulatory effect of mushrooms as anticancer foods was confirmed due to the existence of many phytoconstituents (e.g., lentinan, maitake-D fraction, and schizophyllan), which can upregulate the production of cytokine, cause cell cycle arrest, and mediate cytotoxicity
[53]. The bioactives in edible mushroom spores and their quality as a novel resource for both food and medical compounds were reported by Li et al.
[54]. These bioactive compounds may include the following groups: polysaccharides, amino acids, alkaloids, fatty acids, nucleosides, triterpenes, and others. The role of bioactive metabolites in edible mushrooms in preventing human hair loss was investigated by Tiwari et al.
[55]. They reported that hair loss could be due to the existence of androgenic alopecia (AGA), which occurs because of the hyperactivity of the steroid 5α-reductase2. Many review articles have been published on mushroom bioactives and their therapeutic potential in general (e.g.,
[52][56][57][58][59][60]), or with focus on certain bioactive compounds such as proteins
[61][62], polysaccharides
[63][64][65], non-peptide secondar + y metabolites
[66], terpenoids
[67][68], etc.
Table 3. Some edible mushroom species and their primary bioactive compounds content.
Mushroom Species |
Main Groups of Bioactive Compounds |
Refs. |
Phenolics |
Polysaccharides |
Proteins |
Triterpenoids |
Cordyceps aegerita |
Proto-catechuic acid |
Fucogalactan |
Ageritin |
Bovistols A-C |
Citores et al. [69] |
Boletus edulis |
Gallic acid |
Polysaccharides (BEBP-1) |
β-Trefoil lectin |
Boledulins A-C |
Luo et al. [70] |
Agaricus bisporus |
Gallocatechin |
Heteropolysaccharide ABP |
Protein type FIIb-1 |
Ergosterol |
Liu et al. [71] |
Lactarius deliciosus |
Syringic acid, vanillic acid |
Polysaccharide (LDG-M) |
Laccase |
Azulene-type sesquiterpen |
Su et al. [72] |
Coprinus comatus |
Flavones and flavonols |
Modified polysaccharide |
Laccases |
Terpenoids |
Nowakowski et al. [73] |
Pleurotus ostreatus |
Caffeic acid and ferulic acid |
Mycelium polysaccharides |
Concanavalin A |
Ergosterol |
Fu et al. [74] |
Pleurotus cornucopiae |
Gallic acid |
β-glucan |
Oligopeptides |
Ergostane-type sterols |
Lee et al. [75] |
Macrolepiota procera |
Proto-catechuic acid |
Polysaccharides |
β-Trefoil lectin |
Lanostane triterpenoids |
Chen et al. [76] |
This entry is adapted from the peer-reviewed paper 10.3390/foods12142671