Recent advances and future directions on the valorization of spent mushroom substrate (SMS): A review

Shedding light on Pleurotus: An update on taxonomy, properties, and photobiology

Pleurotus genus (Jacq.) P. Kumm comprises widely known edible mushrooms whose commercial and biotechnological exploitation has been steadily increasing worldwide. With the advent of modern DNA-based approach, the taxonomic definition of species within Pleurotus genus has undergone major changes but remains unclear. Furthermore, knowledge regarding the photobiology of Pleurotus and the role of light in regulating its primary and secondary metabolism, along with key commercial and biotechnological aspects, remains limited. This review aims to depict a comprehensive overview on Pleurotus genus, with a particular focus on its controversial taxonomy, biotechnological potential and photobiology and to provide significant insights to address future research on this topic and exploit light technology to maximize Pleurotus potential.

Mycelium-based composites: An updated comprehensive overview

Mycelium-based composites hold significant potential as sustainable alternatives to traditional materials, offering innovative solutions to the escalating challenges of global warming and climate change. This review examines their production techniques, advantages, and limitations, emphasizing their role in addressing pressing environmental and economic concerns. Current applications span various industries, including manufacturing and biomedical fields, where mycelium-based composites demonstrate the capacity to mitigate environmental impact and enhance economic sustainability. Key findings highlight their environmental benefits, economic viability, and versatile applications, showcasing their potential to revolutionize multiple sectors. However, challenges such as consumer acceptance, intrinsic variability, and the need for standardized guidelines persist, underscoring the importance of further research and innovation. By optimizing material properties and refining production processes, mycelium-based composites could pave the way for widespread adoption as sustainable materials, contributing to a greener and more environmentally conscious future.

Spent Mushroom Substrate-Derived Biochar and Its Applications in Modern Agricultural Systems: An Extensive Overview

Spent mushroom substrate (SMS), a nutrient-dense byproduct of mushroom cultivation, has emerged as a promising feedstock for biochar production, offering a sustainable solution to modern agricultural and environmental challenges. This review explores SMS properties, its conversion into biochar, and its various applications. Due to its lignocellulosic structure, high organic matter (OM), and essential nutrients, SMS is ideal for pyrolysis, a process that enhances biochar's porosity, nutrient retention, and carbon stability. These properties improve soil fertility, water retention, microbial activity, and plant growth while also contributing to climate change mitigation through carbon sequestration. SMS-derived biochar stands out for its superior benefits, including a balanced pH, a rich nutrient profile, and the ability to adsorb heavy metals, which mitigates soil and water contamination and minimizes toxic risks in the food chain. By enhancing soil structure, nutrient cycling, and moisture retention, SMS-derived biochar supports sustainable farming practices that reduce chemical fertilizer use and boost climate resilience. Beyond soil applications, SMS-derived biochar is effective in wastewater treatment, mitigating plant diseases, and improving mushroom cultivation substrates, thereby enhancing mycelial growth and productivity. Economically, it is a cost-effective alternative due to the abundant availability and inexpensive nature of SMS. Nevertheless, challenges still exist, particularly in optimizing production methods and ensuring consistency in biochar properties, influenced by variations in pyrolysis conditions and SMS types. Advances in production technology and sustainable practices are vital for scaling up SMS-derived biochar production. This paper emphasizes the transformative potential of SMS-derived biochar, advocating for its integration into circular economy frameworks and sustainable agricultural systems. Recommendations for future research and policy support are provided to maximize the ecological and economic benefits of SMS-derived biochar, fostering its widespread adoption in global agricultural and environmental strategies.

The bacterial community drive the humification and greenhouse gas emissions during plant residues composting under different aeration rates

This study investigated the effects of different aeration intensities on organic matter (OM) degradation, greenhouse gas emissions (GHG) as well as humification during plant residue composting. Three intermittent aeration intensities of 0.084 (Tlow), 0.19 (Tmedium) and 0.34 (Thigh) L min-1kg-1 DM with 30 min on/30 min off were conducted on a lab-scale composting experiment. Results showed that OM mineralization in Thigh was more evident than Tlow and Tmedium, resulting in the highest humic acid content. Humic acid content in Tmedium and Thigh was 15.7% and 18.5% higher than that in Tlow. The average O2 concentration was 4.9%, 9.5% and 13.6% for Tlow, Tmedium and Thigh. Compared with Tmedium and Thigh, Tlow reduced CO2 and N2O emissions by 18.3%-39.6% and 72.4%-63.9%, but the CH4 emission was highest in Tlow. But the total GHG emission was the lowest in Thigh. Linear Discriminant Analysis Effect Size analysis showed that the core bacteria within Tlow mainly belonged to Anaerolineaceae, which was significantly negatively correlated to the emission of CH4. Thermostaphylospora, Unclassified_Vicinamibacteraceae and Sulfurifustis were identified as core bacteria in Tmedium and Thigh, and these genus were significantly postively correlated to CO2 and N2O emissions. Redundancy analysis showed that total orgnic carbon, O2 and electrical conductivity were the key factors affecting the evolution of bacterial community.

The hidden drivers: Unraveling the impact of density, moisture, and scale on Hermetia illucens rearing

The black soldier fly (Hermetia illucens) is a saprophagous insect known for bioconverting organic waste, potentially offering environmental benefits, such as contributing to waste reduction and nutrient cycling. The performance of larvae varies significantly with factors substrate moisture, larval density, and scale of production. Three experiments were conducted using a mix of spent mushroom substrate (SMS) and chicken feed (CF). In the first experiment, 250 larvae were reared on 100 g dry matter (DM) feed at moisture levels of 65-75%. Results showed that the average individual larval weight, total biomass, and feed conversion ratio (FCR) improved with increased moisture. In the second experiment, 300 and 350 larvae/box were tested at 70% and 75% moisture. The highest average individual larval fresh weight (158.6 mg) was observed at 70% moisture with 250 larvae, while the highest biomass was achieved at 75% moisture with 300 larvae. Finally, different scales (10-2,500 g feed with 25-6,500 larvae) were tested with a similar feeding rate. The highest individual larval weight was recorded at the 100 g scale, with no clear correlation between weight and scale. However, the 50 g scale achieved the highest substrate reduction (33.2%). Overall, this study underscores the need to adjust moisture, density, and scale to nutrient conversion efficiency when using SMS, CF or other diets. The optimal results for the SMS feed mix were observed at 75% substrate moisture, 250 larvae per 100 g DM, and at approximately 2 larvae per cm2.

Spent mushroom substrate: A review on present and future of green applications

The cultivation of edible mushrooms plays a significant role in revitalizing numerous rural regions in China. However, this process generates a large amount of spent mushroom substrate (SMS). Traditional methods for handling SMS, such as random stacking and incineration, lead to resource waste and environmental pollution. The content of organic matter in SMS can range from 40% to 60%, and it also contains various beneficial elements such as trace minerals, making it a valuable resource for biomass. This review initially explores the unique characteristics of SMS and then summarizes the main methods of utilizing its resources. Presently, common resource utilization techniques for SMS include using it as a second-generation cultivation substrate, preparing animal feed and soil fertilizer, producing methane, bioethanol, hydrogen, bio-oil, and electrodes of energy storage devices, extracting enzymes and polysaccharides, and creating bioremediation materials for heavy metals and organic pollutants removal. While research has been conducted on these utilization methods, there are still relatively few large-scale industrial applications. This review also highlights existing challenges and potential solutions in the SMS utilization. Upcycling SMS via innovative and practical technologies presents a promising approach to transforming organic waste into economic value.

Bioconversion efficiency and chemical composition of Hermetia illucens larvae fed spent mushroom substrates

Spent mushroom substrate (SMS) is a by-product remaining after harvesting mushrooms. We evaluated the effect of substituting chicken feed with 0-100% of Pleurotus eryngii and Lentinula edodes SMS at different stocking densities (200-1000 larvae/box) on development, composition, and substrate reduction of black soldier fly (Hermetia illucens) larvae. Although the survival rate was not significantly different, feeding pure SMS led to a low growth rate. The substitution level of SMS negatively correlated with individual larval weight, total harvested biomass, larval growth rate (LGR), feed conversion ratio (FCR), substrate reduction, and waste reduction index (WRI) except for the 20% substitution. Feeding 40% SMS resulted in the highest number of prepupae. In the density experiment, the heaviest larvae (220-239 mg fresh weight) were obtained at 200 larvae/box in the 0% SMS group. The frass residue and FCR decreased with increased density. Remarkably, when feeding 20% SMS at 250 larvae/box, the harvested biomass, LGR, and FCR did not differ significantly from the 0% SMS control, whereas some of the higher densities led to a deterioration. In fact, the frass residue, substrate reduction, and WRI were even improved at 250 larvae/box in the 20% SMS group. The chemical analyses of larvae reared on 20% SMS at 250 larvae/box showed comparable ash and fat contents and a higher protein content compared to the 0% SMS group. Accordingly, up to 20% of a standard diet such as chicken feed can be replaced by low-cost SMS without disadvantages for breeding.

Status and development of spent mushroom substrate recycling: A review

The edible mushroom industry is the sixth largest after grain, cotton, oil, vegetables and fruits, and the annual production of edible mushrooms in China exceeds 40 million tons. Edible mushroom cultivation produces a class of by-products consisting mainly of mycelium remnants and lignocellulosic waste, known as Spent Mushroom Substrate (SMS) or Spent Mushroom Compost (SMC). SMS/SMC is rich in nutrients and active ingredients and has an extremely high recycling potential. This review paper summarizes SMS recycling strategies from the perspectives of "environmental remediation" and "circular economy", and briefly discusses the legitimacy, possible challenges and future research of SMS recycling. It is hoped that this will assist researchers in related fields and promote the development of the SMS recycling industry, thereby contributing to sustainable environmental and economic development.Implications: The efficient management of SMS is important for many countries around the world, particularly major mushroom producing countries. Traditional disposal methods (incineration, burial, piling) can cause serious damage to the environment and waste resources. The correct disposal method can protect the natural environment and provide certain economic benefits. This study presents the main methods of SMS processing from both an "environmental remediation" and "circular economy" perspective. In general, this paper emphasizes the importance of SMS processing, introduces the current mainstream processing methods and briefly discusses the legality of their processing methods.

Speciation characteristics of heavy metal(loid)s in maize-wheat farmland with applying spent mushroom substrates

Spent mushroom substrates (SMS) have been increasingly applied as organic fertilizer worldwide. However, the effects of various SMS on the accumulation and speciation characteristics of soil heavy metal(loid)s (HMs) are generally overlooked. Three types of SMS, including Flammulina velutipes residue (FVR), Agaricus bisporus residue (ABR), and Auricularia auricula residue (AAR), were applied to replace 25 % and 50 % of chemical fertilizer (based on nitrogen application) used in maize-wheat farmland. Compared to chemical fertilizer, the soil Cd, Pb, and As concentrations were decreased by 20.41 %, 5.97 %, and 10.09 %, respectively. And the residual fractions of soil HMs were increased through the application of SMS, indicating a reduction in their bioavailability. Notably, 50 % ABR replacement significantly increased the proportion of residual fraction in soil Cd, Pb, and As by 23.03 %, 15.15 %, and 4.85 %, respectively (P<0.05). A significant negative correlation was observed between the concentrations of HMs in grains and the residual fractions of soil HMs. Thus, compared with chemical fertilizers, the residual fractions of soil HMs were increased by the application of SMS, thereby reducing the concentrations of HMs in grains. Ingestion of crops is the primary route for human exposure to HMs. Therefore, the application of SMS (especially ABR) reduced the accumulation and bioavailability of HMs in soil, which in turn limited the transfer of HMs to crops, resulting in lowered human health risk indices.

Effects of Spent Substrate of Oyster Mushroom (Pleurotus ostreatus) on Feed Utilization and Liver Serum Indices of Hu Sheep from the Perspective of Duodenal Microorganisms

This study aimed to evaluate the effects of Pleurotus ostreatus spent mushroom substrate (P.SMS), which is characterized by high production but low utilization, on feed utilization and liver serum indices from the perspective of duodenal microorganisms. Forty-five 3-month-old Hu sheep were randomly assigned to five groups and fed diets in which whole-plant corn silage (WPCS) was substituted with P.SMS at levels of 0% (Con), 5% (PSMS5), 10% (PSMS10), 15% (PSMS15), or 20% (PSMS20). The results indicated that the addition of P.SMS complexly influenced the apparent digestibility of dry matter, organic matter, and crude protein, with PSMS10 showing the highest digestibility of these nutrients. P.SMS inclusion significantly affected serum alanine aminotransferase levels, with PSMS5 showing higher levels than both the Con and PSMS20 groups (p < 0.05). Importantly, the inclusion of P.SMS did not affect the richness and diversity of duodenal microorganisms. Significant differences in the phyla Verrucomicrobiota and Spirochaetota were observed between the Con and PSMS20 groups. The observed trend towards an increase in the genus Trichoderma (p = 0.057) suggests that P.SMS is susceptible to contamination by this genus, which in turn affects the structure of the intestinal flora. Furthermore, functional gene predictions indicated differences in amino acid metabolism among the groups (p < 0.05). In conclusion, feeding with 10% P.SMS resulted in the highest digestibility without adversely affecting the structure of the duodenal community or liver function.

Innovation and Utilization of Functional Feed Additives from Maize By-Products in Broiler Chickens

Supplementation with spent mushroom substrate (SMS) as an exogenous enzyme in broiler diets represents a promising nutritional strategy to enhance production efficiency and reduce costs. To assess the effects of SMS enzyme products on various parameters, including growth performance, blood chemistry, carcass and meat quality, and gut health, a study was conducted with one-day-old broilers (n = 500). The broilers were separated into five groups: a control diet (CON) and an antibiotic group (AGP) which were added to the diet at 0.25 g kg-1, and SMS from Flammulina velutipes supplementation groups which were added to the diet at 0.5 g kg-1 (SMS0.5), 1.0 g kg-1 (SMS1.0), and 2.0 g kg-1 (SMS2.0). Final body weight and average daily gain in broilers which were fed the AGP diet were higher than in broilers which were fed the CON, SMS0.5, and SMS1.0 diets. Broilers in the CON group had a decreased average daily feed intake compared to other groups. The addition of AGP and SMS2.0 diets improved the feed conversion ratio and reduced the feed cost per gain in broilers. Broilers that were fed the CON diet had the highest serum cholesterol, while the AGP diet increased triglyceride. Dietary supplementation of SMS improved some carcass characteristics and ceacum microbial content in broilers, especially with the SMS2.0 diet. Broiler fed CON and SMS0.5 worsened the villus height/crypt depth ratio of duodenum histology. In conclusion, SMS supplementation at 1.0 and 2.0 g kg-1 can improve productive performance and health in broiler diets; however, SMS2.0 had the best efficiency.

Metagenomic insights into the mechanism of sophorolipid in facilitating co-anaerobic digestion of mushroom residues and cattle manure: Functional microorganisms and metabolic pathway analysis

The present study aimed to enhance the co-anaerobic digestion system of mushroom residues and cattle manure by incorporating biosurfactant sophorolipid. Results demonstrated that the addition of 75 mg/L sophorolipid increased cumulative methane production by 33.68%, acetate content by 9-10 times, and the abundance of Methanosarcina by 69.22%. The electroactive microorganisms (Bacteroides, Petrimonas, etc.) were enriched, while the up-regulation of functional genes associated with carbohydrate metabolism and methane metabolism was observed. The metagenomic analysis revealed the significant involvement of inter-microbial communication and extracellular electron transfer in anaerobic digestion. Petrimonas was identified as the predominant host involved in cellular processes and environmental information processing. The supplementation of sophorolipid significantly enhanced its abundance during the late anaerobic digestion period (by 12.30%-64.84%). The results emphasize the crucial function of sophorolipid as biosurfactant in enhancing the efficiency of anaerobic digestion.

Revalorization of degraded maguey pulquero substrate for Lycopersicon esculentum germination

The bagasse of Agave salmiana (maguey pulquero) is a residue generated during the exploitation of the plant to obtain pulque, inulin, honey, etc. Due to its chemical composition, it can be used for the cultivation of fungi of the Pleurotus genus and the subsequent use of the degraded material "degraded substrate (DS)" as a support for the germination of vegetables. The objective of the study was to characterize the bagasse of maguey pulquero biodegraded by Pleurotus djamor as a new perspective in its value chain, and subsequent use for the germination of Lycopersicon esculetum (tomato). The DS was recovered at 60 d from the P. djamor culture, characterized physicochemically and the conformation of the plant tissue was observed by scanning electron microscopy. The DS showed a decrease in protein (4.8-3.3 %) content and fibrous fraction (54-36 %), but dry matter digestibility increased from 47 to 71 %; in addition, changes in mineral composition were observed, mainly in calcium concentration (6 %). Due to its composition, it is possible to revalue DS in the germination of L. esculetum to reduce the use of peat moss (commercial peat). The results show that up to 25 % of maguey DS mixed with 75 % peat moss can be used (25:75), reaching a germination percentage of 85 % and increasing the seedling emergence speed index from 0.96 - 1.25. Concluding that it is possible to implement a circular strategy in which agave bagasse is used for mushroom cultivation and the subsequent recovery of the spent substrate for tomato germination.

Effects of black soldier fly larvae on biotransformation and residues of spent mushroom substrate and wet distiller's grains

Black soldier fly larvae (BSFL) could convert a variety of organic wastes, including spent mushroom substrate (SMS) and wet distiller's grains (WDG). Nevertheless, little is known about the conversion of these wastes by BSFL. Thus, this study investigates the conversion of SMS and WDG in five different proportions by BSFL. This study demonstrates that BSFL can convert SMS, WDG, and their mixtures. It can also encourage the humification of the substrate, increasing the amount of element in the residues. It is evident that there were differences in the carbon and nitrogen element fractionation mode as well as the microbial community present in the residue. The microbial community of the substrate and the physiochemical parameters are intimately related to this. Although the mixture treated with BSFL helps to generate a residue with more humus, it might not be stable.

Mushroom By-Products as a Source of Growth Stimulation and Biochemical Composition Added-Value of Pleurotus ostreatus, Cyclocybe cylindracea, and Lentinula edodes

Spent mushroom substrates (SMSs) and mushroom basal bodies (MBBs) are significant by-products because of their nutrient content even after harvesting. This study aimed to evaluate the effect of these two by-products, derived from Agaricus bisporus (Ab) and Cyclocybe cylindracea (Cc) cultivation, as potential growth and biochemical composition add-value enhancers of edible mushroom mycelia such as Pleurotus ostreatus, C. cylindracea, and Lentinula edodes. Fungal growth substrates enriched with SMS and MBB extracts significantly affected the growth of mushroom mycelia. In particular, on P. ostreatus, the MBBs Ab and Cc extracts determined an increase in mycelial weight by 89.5%. Also, by-products influenced mushrooms' mycelial texture, which appeared more floccose and abundant in growth. FT-IR analysis showed that L. edodes mycelium, grown on MBB substrates, showed the highest increase in bands associated with proteins and chitin. Results demonstrated that mushroom by-products enhance mycelial growth and confer an enrichment of compounds that could increase mycelial resistance to pathogens and make a nutraceutical improvement.

Advancing Cordyceps militaris Industry: Gene Manipulation and Sustainable Biotechnological Strategies

Cordyceps militaris is considered to be of great medicinal potential due to its remarkable pharmacological effects, safety, and edible characteristics. With the completion of the genome sequence and the advancement of efficient gene-editing technologies, coupled with the identification of gene functions in Cordyceps militaris, this fungus is poised to emerge as an outstanding strain for medicinal engineering applications. This review focuses on the development and application of genomic editing techniques, including Agrobacterium tumefaciens-mediated transformation (ATMT), PEG-mediated protoplast transformation (PMT), and CRISPR/Cas9. Through the application of these techniques, researchers can engineer the biosynthetic pathways of valuable secondary metabolites to boost yields; such metabolites include cordycepin, polysaccharides, and ergothioneine. Furthermore, by identifying and modifying genes that influence the growth, disease resistance, and tolerance to environmental stress in Cordyceps militaris, it is possible to stimulate growth, enhance desirable traits, and increase resilience to unfavorable conditions. Finally, the green sustainable industrial development of C. militaris using agricultural waste to produce high-value-added products and the future research directions of C. militaris were discussed. This review will provide future directions for the large-scale production of bioactive ingredients, molecular breeding, and sustainable development of C. militaris.

Micropollutants (ciprofloxacin and norfloxacin) remediation from wastewater through laccase derived from spent mushroom waste: Fate, toxicity, and degradation

Fluoroquinolone antibiotics frequently found in environmental matrices (wastewater treatment plants, hospital wastewater, industrial wastewater and surface wastewater) causes potential threat to the environment. Enzymatic treatment for degradation of antibiotics from environmental matrices is a green and sustainable approach. Focusing on this, this study aimed to degrade two frequently found fluroquinolone emergent pollutants, ciprofloxacin and norfloxacin from wastewater. The trinuclear cluster of copper ions present in laccase has the ability to effectively remove organic micropollutants (OMPs). The uniqueness of this study is that it utilizes laccase enzyme extracted from spent mushroom waste (SMW) of P. florida for degradation of ciprofloxacin and norfloxacin and to achieve highest degradation efficiency various parameters were tweaked such as pH (3-6), temperature (30 °C and 50 °C), and ABTS (0.05, 0.6, and 1 mM) concentration. The results showed that the most effective degradation of ciprofloxacin (86.12-75.94%) and norfloxacin (83.27-65.94%) was achieved in 3 h at pH 4.5, temperature 30 °C, and 2,2'-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 0.05 mM concentration. Nevertheless, achieving degradation at 50 °C for both antibiotics, indicates thermostability nature of laccase (P. florida). Further, the fate of transformed products obtained from laccase mediated degradation was confirmed by liquid chromatography (LC-MS). Both the antibiotics undergo decarboxylation, depiperylyzation, dealkylation and defluorination as a result of laccase-mediated bond breakage. Anti-microbial activity of the biodegraded products was monitored by residual anti-bacterial toxicity test (E. coli and Staphylococcus aureus). The biodegraded products were found to be non-toxic and resulted in the growth of E. coli and Staphylococcus aureus, as determined by the agar-diffusion method. Moreover, the storage stability of laccase was determined for 28-day duration at varying pH (3-10) and temperature (4-50 °C). The maximum storage stability was obtained at pH 4.5 and temperature 30 °C. Therefore, utilizing SMW for the degradation of OMPs from wastewater not only benefits in degradation but also reuses SMW agro waste, shedding light on agro waste management. Thus, SMW is a one-pot solution for both OMPs biodegradation and circularity in the economy.

Unearthing the therapeutic benefits of culinary-medicinal mushrooms for humans: Emerging sustainable bioresources of 21st century

Global interest in mushroom farming techniques has grown in the last few years. Despite not making up a large amount of the human diet at the moment, the nutritional worth of mushrooms has prompted their usage. The three main segments of the global mushroom industry are wild, culinary (edible), and medicinal mushrooms. The quality food that mushrooms provide can be utilized to build agricultural ecosystems that are more sustainable for increasing productivity and enhancing the effectiveness of resource usage. This is mostly because mushrooms can be utilized for the recycling of biomass and remains from crop production. Culinary-medicinal mushrooms are becoming more and more important because of their nutrient density, dietary value, and health advantages. Given its many bioactive components, which include polysaccharides, proteins, vitamins, minerals, dietary fiber, and secondary metabolites, mushrooms have been utilized extensively as health foods. These mushrooms exhibit pharmacological activities and possess prebiotic and antibacterial capabilities. This review provides information on the latest advancements in the sustainable cultivation of mushrooms, particularly with nontraditional substrates, and their potential therapeutic uses. Furthermore, some of the newest developments and difficulties in the production of mushrooms are explored.

Spent Mushroom Substrate Improves Microbial Quantities and Enzymatic Activity in Soils of Different Farming Systems

Organic fertilizers, such as spent mushroom substrate (SMS), improve soil fertility, but studies comparing their effects on different agricultural soils are limited. In this study, the effects of standard, SMS and composed fertilizers on soils from conventional-integrated, organic and biodynamic farming were investigated. Soil samples were analyzed for microorganisms and the activity of β-glucosidase (β-GLU), β-1,4-N-acetylglucosaminidase (NAG), urease (URE), arylamidase (ARN), phosphatase (PHOS), acid phosphatase (PAC), alkaline phosphatase (PAH) and arylsulphatase (ARS). Biodynamic soil showed the highest microbial counts and enzyme activities, followed by organic and conventional soils. SMS significantly increased the number of microorganisms and enzyme activities, especially in biodynamic and organic soils. Seasonal variations affected all microorganisms and most enzymes in all soils, except NAG in conventional and organic soils. Biodynamic soil showed stable activity of enzymes and microorganisms throughout the year, indicating greater stability. This study concludes that soil microorganisms and enzyme activities respond differently to fertilization depending on the soil type, with SMS demonstrating beneficial effects in all tested soils.

Plant-Derived Waste as a Component of Growing Media: Manifestations, Assessments, and Sources of Their Phytotoxicity

Every year, approximately 2 billion tons of plant-derived waste (such as straw and crop residues) are generated globally, most of which are either incinerated, dumped, or landfilled without proper planning, leading to severe environmental pollution and resource wastage. Plant-derived waste exhibits potential advantages as a growing media component in various aspects. However, numerous studies have also indicated that plant-derived waste generally possesses strong phytotoxicity, which must be removed or reduced before being utilized as a growing media component. Therefore, accurately assessing their phytotoxicity and appropriately modifying it to ensure their support for plant growth when used as a growing media component is crucial. This paper reviews the manifestation and assessment methods of phytotoxicity in plant-derived waste; systematically summarizes the phytotoxicity sources of three common types of plant-derived waste (garden waste, crop straw, and spent mushroom substrate), as well as the toxic mechanisms of two representative phytotoxic substances (phenolic compounds and organic acids); and proposes some insights into further research directions. By consolidating insights from these studies, this review aims to deepen our understanding of phytotoxicity and its implications, and offer valuable references and guidance for future research endeavors and practical applications.

Enhancing biodegradation of vegetable oil-contaminated soil with soybean texturized waste, spent mushroom substrate, and stabilized poultry litter in microcosm systems

Industrial activities contribute to environmental pollution, particularly through unregulated effluent discharges, causing adverse effects on ecosystems. Vegetable oils, as insoluble substances, exacerbate this pollution, forming impermeable films and affecting the oxygen transfer, leading to serious habitat disruption. Organic wastes, such as soybean texturized waste, spent mushroom substrate, and stabilized poultry litter, were assessed for their efficacy in enhancing the degradation of vegetable oil in contaminated soil. For this purpose, contaminated soil was amended with each of the wastes (10% w/w) using microcosm systems, which were monitored physico-chemically, microbiologically and toxicologically. Results indicate that the wastes promoted significant oil degradation, achieving 83.1, 90.7, and 86.2% removal for soybean texturized waste, spent mushroom substrate, and stabilized poultry litter, respectively, within a 90-day period. Additionally, they positively influenced soil microbial activity, as evidenced by increased levels of culturable microorganisms and hydrolytic microbial activity. While bioassays indicated no phytotoxicity in most cases, soybean texturized waste exhibited inhibitory effects on seed germination and root elongation of Lactuca sativa. This study significantly enhances our comprehension of remediation techniques for sites tainted with vegetable oils, highlighting the critical role of organic waste as eco-friendly agents in soil restoration. Emphasizing the practical implications of these findings is imperative to underscore the relevance and urgency of addressing vegetable oil contamination in soil. Moving forward, tailored strategies considering both contaminant characteristics and soil ecosystem traits are vital for ensuring effective and sustainable soil remediation.

Impact of Lactic Acid Bacteria Fermentation Based on Biotransformation of Phenolic Compounds and Antioxidant Capacity of Mushrooms

Mushrooms contain phenolic compounds that possess health-promoting properties, including antioxidant effects. However, the low solubility and form of phenolic compounds affect their bioactivity and bioaccessibility. To overcome this limitation, our study investigates the fermentation of mushrooms to increase their free phenolic content and enhance their bioactivity. Our research focused on the impact of fermentation on both free and bound phenolic fractions (FPs and BPs, respectively) in Lentinula edodes and Lactarius deliciosus, which were successively fermented with Lactiplantibacillus plantarum LMG 17673 for 72 h. We examined the total phenolic content (TPC), phenolic profile, and antioxidant activity of both FPs and BPs. Our results showed that the TPC of BPs was higher than that of FPs in both mushrooms, with strong antioxidant capabilities. Fermentation significantly increased the TPC of FPs in both mushrooms, particularly after 24 h of fermentation. The TPC of BPs in mushrooms decreased during fermentation, indicating their release from the matrix. Additionally, we identified 30 bioactive compounds using UPLC-Q-TOF-MS/MS. Our study demonstrates for the first time that lactic acid bacteria fermentation of mushrooms with high phenolic content leads to the liberation of bound phenolics, enhancing their bioactivity and bioaccessibility.

Changes in soil organic carbon components and microbial community following spent mushroom substrate application

While spent mushroom substrate (SMS) has shown promise in increasing soil organic carbon (SOC) and improving soil quality, research on the interplay between SOC components and microbial community following the application of diverse SMS types remains scant. A laboratory soil incubation experiment was conducted with application of two types of SMSs from cultivation of Pleurotus eryngii (PE) and Agaricus bisporus (AB), each at three application rates (3, 5.5, and 8%). Advanced techniques, including solid-state 13C nuclear magnetic resonance (NMR) and high-throughput sequencing, were employed to investigate on SOC fractions and chemical structure, microbial community composition and functionality. Compared to SMS-AB, SMS-PE application increased the relative abundances of carbohydrate carbon and O-alkyl C in SOC. In addition, SMS-PE application increased the relative abundance of the bacterial phylum Proteobacteria and those of the fungal phyla Basidiomycota and Ascomycota. The relative abundances of cellulose-degrading bacterial (e.g., Flavisolibacter and Agromyces) and fungal genera (e.g., Myceliophthora, Thermomyces, and Conocybe) were increased as well. The application of SMS-AB increased the aromaticity index of SOC, the relative abundance of aromatic C, and the contents of humic acid and heavy fraction organic carbon. In addition, SMS-AB application significantly increased the relative abundances of the bacterial phyla Firmicutes and Actinobacteria. Notably, the genera Actinomadura, Ilumatobacter, and Bacillus, which were positively correlated with humic acid, experienced an increase in relative abundance. Functional prediction revealed that SMS-PE application elevated carbohydrate metabolism and reduced the prevalence of fungal pathogens, particularly Fusarium. The application of high-rate SMS-AB (8%) enhanced bacterial amino acid metabolism and the relative abundances of plant pathogenic fungi. Our research provides strategies for utilizing SMS to enrich soil organic carbon and fortify soil health, facilitating the achievement of sustainable soil management.

Innovative utilization of harvested mushroom substrate for green synthesis of silver nanoparticles: A multi-response optimization approach

In this work, harvested mushroom substrate (HMS) has been explored for the first time through a comprehensive optimization study for the green synthesis of silver nanoparticles (AgNPs). A multiple response central composite design with three parameters: pH of the reaction mixture, temperature, and incubation period at three distinct levels was employed in the optimization study. The particle size of AgNPs, UV absorbance, and the percentage of Ag/Cl elemental ratio were considered as the response parameters. For each response variable examined the model used was found to be significant (P < 0.05). The ideal conditions were: pH 8.9, a temperature of 59.4 °C, and an incubation period of 48.5 h. The UV-visible spectra of AgNPs indicated that the absorption maxima for AgNP-3 were 414 nm, 420 for AgNPs-2, and 457 for AgNPs-1. The XRD analysis of AgNPs-3 and AgNPs-2 show a large diffraction peak at ∼38.2°, ∼44.2°, ∼64.4°, and ∼77.4°, respectively, which relate to the planes of polycrystalline face-centered cubic (fcc) silver. Additionally, the XRD result of AgNPs-1, reveals diffraction characteristics of AgCl planes (111, 200, 220, 311, 222, and 400). The TEM investigations indicated that the smallest particles were synthesized at pH 9 with average diameters of 35 ± 6 nm (AgNPs-3). The zeta potentials of the AgNPs are -36 (AgNPs-3), -28 (AgNPs-2), and -19 (AgNPs-1) mV, respectively. The distinct IR peak at 3400, 1634, and 1383 cm-1 indicated the typical vibration of phenols, proteins, and alkaloids, respectively. The AgNPs were further evaluated against gram (+) strain Bacillus subtilis (MTCC 736) and gram (-) strain Escherichia coli (MTCC 68). All of the NPs tested positive for antibacterial activity against both bacterial strains. The study makes a sustainable alternative to disposing of HMS to achieve the Sustainable Development Goals (SDGs).

Enzymatic and non-enzymatic removal of organic micropollutants with spent mushroom substrate of Agaricus bisporus

Water bodies are increasingly contaminated with a diversity of organic micropollutants (OMPs). This impacts the quality of ecosystems due to their recalcitrant nature. In this study, we assessed the removal of OMPs by spent mushroom substrate (SMS) of the white button mushroom (Agaricus bisporus) and by its aqueous tea extract. Removal of acesulfame K, antipyrine, bentazon, caffeine, carbamazepine, chloridazon, clofibric acid, and N, N-diethyl-meta-toluamide (DEET) by SMS and its tea was between 10 and 90% and 0-26%, respectively, in a 7-day period. Sorption to SMS particles was between 0 and 29%, which can thus not explain the removal difference between SMS and its tea, the latter lacking these particles. Carbamazepine was removed most efficiently by both SMS and its tea. Removal of OMPs (except caffeine) by SMS tea was not affected by heat treatment. By contrast, heat-treatment of SMS reduced OMP removal to < 10% except for carbamazepine with a removal of 90%. These results indicate that OMP removal by SMS and its tea is mediated by both enzymatic and non-enzymatic activities. The presence of copper, manganese, and iron (0.03, 0.88, and 0.33 µg L-1, respectively) as well as H2O2 (1.5 µM) in SMS tea indicated that the Fenton reaction represents (part of) the non-enzymatic activity. Indeed, the in vitro reconstituted Fenton reaction removed OMPs > 50% better than the teas. From these data it is concluded that spent mushroom substrate of the white button mushroom, which is widely available as a waste-stream, can be used to purify water from OMPs.

Fungal Carbon: A Cost-Effective Tunable Network Template for Creating Supercapacitors

Carbons form critical components in biogas purification and energy storage systems and are used to modify polymer matrices. The environmental impact of producing carbons has driven research interest in biomass-derived carbons, although these have yield, processing, and resource competition limitations. Naturally formed fungal filaments are investigated, which are abundantly available as food- and biotechnology-industry by-products and wastes as cost-effective and sustainable templates for carbon networks. Pyrolyzed Agaricus bisporus and Pleurotus eryngii filament networks are mesoporous and microscale with a size regime close to carbon fibers. Their BET surface areas of ≈282 m2 g-1 and ≈60 m2 g-1, respectively, greatly exceed values associated with carbon fibers and non-activated pyrolyzed bacterial cellulose and approximately on par with values for carbon black and CNTs in addition to pyrolyzed pinewood, rice husk, corn stover or olive mill waste. They also exhibit greater specific capacitance than both non-activated and activated pyrolyzed bacterial cellulose in addition to YP-50F (coconut shell based) commercial carbons. The high surface area and specific capacitance of fungal carbon coupled with the potential to tune these properties through species- and growth-environment-associated differences in network and filament morphology and inclusion of inorganic material through biomineralization makes them potentially useful in creating supercapacitors.

Low uptake of pharmaceuticals in edible mushrooms grown in polluted biogas digestate

The uptake dynamics of two sulfonamide antibiotics, two fluoroquinolone antibiotics, and the anticonvulsant carbamazepine during the cultivation of two species of edible mushrooms (Agaricus subrufescens and A. bisporus) was investigated. None of the antibiotics were accumulated by the mushrooms, while carbamazepine and its transformation product carbamazepine-10,11-epoxide were taken up by A. bisporus fruiting body but only in small amounts (up to 0.76 and 1.85 μg kg-1 dry weight, respectively). The sulfonamides were quickly removed from the mushroom growth substrate, while the recalcitrant fluoroquinolones and carbamazepine were only partially removed. Dissipation half-lives were generally lower for A. subrufescens than A. bisporus, but A. subrufescens was also grown at a slightly higher culture temperature. A. subrufescens also showed a lower uptake of contaminants. Comparison of maximum dietary intake with other common exposure sources showed that these mushrooms can safely be eaten although produced on a polluted substrate, with respect to the investigated compounds.

Exploration of the biodegradation pathway and enhanced removal of imazethapyr from soil by immobilized Bacillus marcorestinctum YN1

Excessive or inappropriate applications of imazethapyr cause severe ecological deteriorations and health risks in human. A novel bacterial strain, i.e., Bacillus marcorestinctum YN1, was isolated to efficiently degrade imazethapyr, with the degradation pathways and intermediates predicted. Protein mass spectrometry analysis identified enzymes in strain YN1 potentially involved in imazethapyr biodegradation, including methylenetetrahydrofolate dehydrogenase, carbon-nitrogen family hydrolase, heme degrading monooxygenase, and cytochrome P450. The strain YN1 was further immobilized with biochar (BC600) prepared from mushroom waste (i.e., spent mushroom substrate) by pyrolysis at 600 °C to evaluate its degrading characteristics of imazethapyr. Scanning electron microscope observation showed that strain YN1 was adsorbed in the rich pore structure of BC600 and the adsorption efficiency reached the maximum level of 88.02% in 6 h. Both energy dispersive X-ray and Fourier transform infrared spectroscopy analyses showed that BC600 contained many elements and functional groups. The results of liquid chromatography showed that biochar-immobilized strain YN1 (IBC-YN1) improved the degradation rate of imazethapyr from 79.2% to 87.4%. The degradation rate of imazethapyr by IBC-YN1 could still reach 81.0% in the third recycle, while the bacterial survival rate was 67.73% after 180 d storage at 4 °C. The treatment of IBC-YN1 significantly shortened the half-life of imazethapyr in non-sterilized soil from 35.51 to 11.36 d, and the vegetative growth of imazethapyr sensitive crop plant (i.e., Cucumis sativus L.) was significantly increased in soil remediated, showing that the inhibition rate of root length and fresh weight were decreased by 12.45% and 38.49% respectively. This study exhanced our understanding of microbial catabolism of imazethapyr, and provided a potential in situ remediation strategy for improving the soil environment polluted by imazethapyr.

Responses of Crop Yield, Soil Fertility, and Heavy Metals to Spent Mushroom Residues Application

Waste mushroom residues are often returned to fields as organic amendments. Here, we estimated the effects of the continuous applications of different spent mushroom substrates for 2 years on crop yields, soil nutrients, and heavy metals in paddy fields. The study comprised seven treatments: no fertilization (CK) and mineral NPK fertilizer (CF), as well as NPK fertilizer combined with Enoki mushroom residue (EMR50), Oyster mushroom residue (OMR50), Auricularia polytricha mushroom residue (APR50), Shiitake mushroom residue (SMR50), and Agaricus bisporus residue (ABR50). The grain yield was highest under the APR50 treatment. The short-term application of waste mushroom residue significantly increased SOC, TN, TP, and TK content relative to the CK treatment. The SOC, TP, and TK were highest under ABR50. Both total Cr and Cd contents were highest under CF treatment. The highest cumulative ecological risk was observed under OMR50 treatment. In addition, crop yield was positively correlated with SOC, TN, TP, and TP. Our results highlight that further research and innovation are needed to optimize the benefits and overcome the challenges of mushroom residue application.

Investigation of pre-treatment techniques on spent substrate of Pleurotus ostreatus for enhanced biobutanol production using Clostridium acetobutylicum MTCC 11274

Addressing global energy demand, researchers sought eco-friendly biobutanol production from lignocellulosic waste biomass. In the present research work, five different pre-treatment methods viz., Microwave, Ultrasound, Alkali, Acid, and Hybrid, were investigated to explore its biobutanol production potential by utilizing Pleurotus ostreatus spent as substrate. The compositional and physico-chemical changes of the pre-treated Spent Mushroom Substrate (SMS) were assessed using SEM, FTIR, and XRD. Hybrid pre-treatment (Microwave, Alkali, Ultrasound) showed higher delignification when compared to conventional pre-treatment method. Hybrid pre-treated SMS resulted in higher total reducing sugars (521.53 ± 1.84 mg/g) than indigenous SMS (267.89 ± 1.53 mg/g). Fermentation of hybrid pre-treated SMS with Clostridium acetobutylicum MTCC 11274 produced the highest biobutanol concentration (9.84 ± 0.03 g/L) and yielded 0.38 ± 0.02 g/g of biobutanol. This study revealed that hybrid pre-treatment could be a promising solution for enhanced biobutanol production using SMS biomass.

Biochar obtained from alkaline earth metal-treated mushroom residue: Thermal behavior and methyl orange adsorption capability

To achieve the resource utilization of edible fungi residue and obtain efficient adsorbents for treating dyeing wastewater, biochars were prepared from mushroom residue (MR) with the introduction of alkaline-earth metals (AEMs) and used for methyl orange (MO) wastewater treatment. The thermal behavior of the AEM-treated MR was analyzed using thermogravimetric analysis. The physicochemical properties of the biochars obtained from AEM-treated MR (MRCs) were characterized using Fourier transform infrared spectroscopy, laser particle size analyzer, N2 adsorption/desorption, and scanning electron microscopy. The adsorption performance of MRCs on MO was also investigated. The involvement of AEMs was found to obviously move the main pyrolysis zone of MR to a low temperature region and reduce the temperature corresponding to the maximum weight loss rate and activation energy, which is highly dependent on the concentration of AEMs, the anion and cationic species of the AEMs. Moreover, the addition of AEMs resulted in a decrease in oxygen-containing functional groups (-OH, CO, or C-O), a weakening of surface negative charges, an enhancement in aromatic functional groups, and an increase in specific surface area of the MRCs. The adsorption performance of MO on MRCs was significantly improved with the introduction of AEMs as well. Among them, MR pre-treated with 5 mmol/g MgCl2 (MR-MgCl2-5) shows the lowest temperature corresponding to the maximum weight loss rate and the lowest activation energy of 278.52 °C and 4.28 kJ/mol, respectively. The biochar prepared from MR-MgCl2-5 under 400 °C (MR-MgCl2-5-400C) has the weakest surface negative charge and the highest adsorption capacity for MO. The adsorption isotherms, adsorption kinetics, and thermodynamic analysis results showed that the adsorption of MO on MR-MgCl2-5-400C was a spontaneous, chemically dominant monolayer adsorption, with a theoretical maximum adsorption capacity of 81.30 mg/g. This study suggests that AEMs treatment, especially with 5 mmol/g MgCl2, can readily transform edible fungi residue into a low-cost, high-efficient dyeing wastewater adsorbent.

Peach palm shells (Bactris gasipaes Kunth) bioconversion by Lentinula edodes: Potential as new bioproducts for beef cattle feeding

This paper aims to develop and assess the in vitro effects on ruminal fermentation and greenhouse gas parameters of new bioproducts for beef cattle diets, carried out by solid-state fermentation of peach palm shells colonized by Lentinula edodes (SSF) and after Shiitake mushroom cultivation in axenic blocks (SMS). In vitro experiments were performed to assess the in vitro gas production, digestibility, and fiber degradation of formulated total diets. Bioproducts presented high β-glucans (9.44---11.27 %) and protein (10.04---8.35 %) contents, as well as similar digestibility to conventional diets. SMS diet had the lowest methane and carbon dioxide (19.1 and 84.1 mM/g OM) production, and the SSF diet presented lower carbon dioxide production (98.9 mM/g OM) than other diets, whereas methane was similar. This study highlighted a sustainable use of byproducts for beef cattle diets, promising for digestibility, nutritional value, β-glucans incorporation, and environmental impact mitigation, favoring the circular bioeconomy.

Effects of Flammulina velutipes mushroom residues on growth performance, apparent digestibility, serum biochemical indicators, rumen fermentation and microbial of Guizhou black goat

Introduction

The primary objective of the current study was to evaluate the effects of Flammulina velutipes mushroom residue (FVMR) in a fermented total mixed ration (FTMR) diet on the fattening effect and rumen microorganisms in Guizhou black male goats.

Methods

A total of 22 Guizhou black male goats were allocated into two groups using the Randomized Complete Block Design (RCBD) experimental design. The average initial weight was 22.41 ± 0.90 kg and with 11 goats in each group. The control group (group I) was fed the traditional fermentation total mixed ration (FTMR) diet without FVMR. Group II was fed the 30% FVMR in the FTMR diet.

Results

The results showed that compared with group I, the addition of FVMR in the goat diet could reduce the feed cost and feed conversion ratio (FCR) of group II (p < 0.01). Notably, the apparent digestibility of crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and dry matter (DM) were higher in group II (p < 0.01). The levels of growth hormone (GH), immunoglobulin A (IgA), and immunoglobulin M (IgM) in group II were higher than that of group I (p < 0.01), which the level of glutamic oxalacetic transaminase (ALT) and interleukin-6 (IL-6) was noticeably lower than that of group I (p < 0.01). 30% FVMR in FTMR diets had no effect on rumen fermentation parameters and microbial composition at the phylum level of Guizhou black male goats (p > 0.05). However, at the genus level, the relative abundance of bacteroidal_bs11_gut_group, Christensenellaceae_R-7_group and Desulfovibrio in group II was lower than in group I (p < 0.05), and the relative abundance of Lachnospiraceae_ND3007_group was higher than in group I (p < 0.01).

Discussion

In conclusion, the results of the current study indicated that 30% FVMR in the FTMR diet improves rumen fermentation and rumen microbial composition in Guizhou black male goats, which improves growth performance, apparent digestibility, and immunity.

Lignocellulolytic Potential of Microbial Consortia Isolated from a Local Biogas Plant: The Case of Thermostable Xylanases Secreted by Mesophilic Bacteria

Lignocellulose biomasses (LCB), including spent mushroom substrate (SMS), pose environmental challenges if not properly managed. At the same time, these renewable resources hold immense potential for biofuel and chemicals production. With the mushroom market growth expected to amplify SMS quantities, repurposing or disposal strategies are critical. This study explores the use of SMS for cultivating microbial communities to produce carbohydrate-active enzymes (CAZymes). Addressing a research gap in using anaerobic digesters for enriching microbiomes feeding on SMS, this study investigates microbial diversity and secreted CAZymes under varied temperatures (37 °C, 50 °C, and 70 °C) and substrates (SMS as well as pure carboxymethylcellulose, and xylan). Enriched microbiomes demonstrated temperature-dependent preferences for cellulose, hemicellulose, and lignin degradation, supported by thermal and elemental analyses. Enzyme assays confirmed lignocellulolytic enzyme secretion correlating with substrate degradation trends. Notably, thermogravimetric analysis (TGA), coupled with differential scanning calorimetry (TGA-DSC), emerged as a rapid approach for saccharification potential determination of LCB. Microbiomes isolated at mesophilic temperature secreted thermophilic hemicellulases exhibiting robust stability and superior enzymatic activity compared to commercial enzymes, aligning with biorefinery conditions. PCR-DGGE and metagenomic analyses showcased dynamic shifts in microbiome composition and functional potential based on environmental conditions, impacting CAZyme abundance and diversity. The meta-functional analysis emphasised the role of CAZymes in biomass transformation, indicating microbial strategies for lignocellulose degradation. Temperature and substrate specificity influenced the degradative potential, highlighting the complexity of environmental-microbial interactions. This study demonstrates a temperature-driven microbial selection for lignocellulose degradation, unveiling thermophilic xylanases with industrial promise. Insights gained contribute to optimizing enzyme production and formulating efficient biomass conversion strategies. Understanding microbial consortia responses to temperature and substrate variations elucidates bioconversion dynamics, emphasizing tailored strategies for harnessing their biotechnological potential.

Valorizing spent mushroom substrate into syngas by the thermo-chemical process

This study investigated the conversion of agricultural biomass waste (specifically, spent mushroom substrate) into syngas via pyrolysis. Carbon dioxide was used to provide a green/sustainable feature in the pyrolysis process. All the experimental data highlight the mechanistic role of carbon dioxide (CO2) in the process, demonstrated by the enhanced carbon monoxide (CO) yield from pyrolysis under CO2. Carbon dioxide was indeed reactive at ≥ 500 ˚C. Carbon dioxide was reduced and subsequently oxidized volatiles stemming from the thermolysis of spent mushroom substrate via the gas-phase reaction, thereby resulting in the enhanced formation of CO. Carbon dioxide radically diverted the carbon distribution patterns of the pyrogenic products, as more carbon in the oil was allocated to syngas by the gas-phase reaction of volatiles and CO2. To enhance the mechanistic role of CO2, a Ni-based catalyst was added to the pyrolysis process, which greatly accelerated the gas-phase reaction of volatiles and CO2.

Nutraceutical Potential of Lentinula edodes' Spent Mushroom Substrate: A Comprehensive Study on Phenolic Composition, Antioxidant Activity, and Antibacterial Effects

Lentinula edodes, commonly known as shiitake mushroom, is renowned for its potential health advantages. This research delves into the often-overlooked by-product of shiitake cultivation, namely spent mushroom substrate (SMS), to explore its nutraceutical properties. The SMS samples were collected and subjected to different extraction methods, namely short or long agitation, and ultrasound-assisted extractions using different temperatures and distilled water or a 50% (v/v) ethanol as solvents. The extracts were tested for phenolic content (total phenols, ortho-diphenols, and flavonoids), antioxidant capacity (DPPH, 2,2-diphenyl-1 picrylhydrazyl; ABTS, 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid; and FRAP, ferric reducing antioxidant power), and antibacterial activity. The different extraction methods revealed substantial variations (p < 0.05) in phenolic composition and antioxidant capacity. The highest phenolic content and antioxidant capacity were achieved using 24 h extraction, agitation, 50 °C, and ethanol as the solvent. Furthermore, the extracted compounds displayed antibacterial activity in specific tested bacterial strains. This study highlights the nutraceutical potential of L. edodes' SMS, positioning it as a valuable dietary supplement for animal nutrition, with emphasis on its prebiotic properties. Hence, this research unveils the promising health benefits of SMS in both human and animal nutrition.

Spent substrate from mushroom cultivation: exploitation potential toward various applications and value-added products

Spent mushroom substrate (SMS) is the residual biomass generated after harvesting the fruitbodies of edible/medicinal fungi. Disposal of SMS, the main by-product of the mushroom cultivation process, often leads to serious environmental problems and is financially demanding. Efficient recycling and valorization of SMS are crucial for the sustainable development of the mushroom industry in the frame of the circular economy principles. The physical properties and chemical composition of SMS are a solid fundament for developing several applications, and recent literature shows an increasing research interest in exploiting that inherent potential. This review provides a thorough outlook on SMS exploitation possibilities and discusses critically recent findings related to specific applications in plant and mushroom cultivation, animal husbandry, and recovery of enzymes and bioactive compounds.

Use of oyster mushrooms (Pleurotus ostreatus) for increased circularity and valorization of rapeseed residues

In Europe, rapeseed is a common oilseed crop, resulting in the production of 20 million tons of rapeseed press cake yearly. This press cake can be further upcycled and a protein fraction can be extracted for food purposes, leaving de-proteinized fiber-rich residues. This study examined the use of these residues in the production of oyster mushrooms (Pleurotus ostreatus) and of the spent substrate as feed, since mushroom cultivation may improve the feed properties of substrate. In terms of mushroom production, the addition of rapeseed press residues was beneficial, giving significantly higher biological efficiency (BE = 93.1 ± 11.0%) compared with the control, sugar beet pulp substrate (70.0 ± 6.6%). This increase in productivity can most likely be explained by higher energy content in the substrate supplemented with lipid-rich rapeseed residues. Despite differences in BE between the substrates, high similarity was observed in lipid composition of the fruiting bodies (lipid profile dominated by linoleic acid (18:2), palmitic acid (16:0), and oleic acid (18:1)), and in protein and moisture content. After mushroom harvest, approximately 70% of the initial dry weight of both substrates remained as a possible feed source. Both substrates had significantly lower levels of carbohydrates and unchanged neutral detergent fiber content after mushroom harvest, and both gave lower in vitro digestibility, total gas production, and methane production. However, protein concentration differed between the substrates, with the highest concentration (15.8% of dry weight) found in spent substrate containing rapeseed press residues. The result of the present study suggests that the de-proteinized rapeseed press residue is a resource well-suited for use in the production of mushrooms and feed.

Unlocking the Potential of Spent Mushroom Substrate (SMS) for Enhanced Agricultural Sustainability: From Environmental Benefits to Poultry Nutrition

In this comprehensive review, we delve into the myriad applications of spent mushroom substrate (SMS) in agricultural contexts, with a particular emphasis on its role in fostering sustainable poultry production. Our examination spans three key domains: the use of SMS in fertilizers, its impact on environmental factors and gas emissions, and its contribution to poultry nutrition. This review synthesizes findings from multiple studies that underscore the potential of composted SMS as a viable alternative to conventional inorganic fertilizers, effectively meeting crop nutrient needs while mitigating groundwater contamination risks. Moreover, we highlight the substantial environmental advantages associated with the utilization of SMS and poultry waste, including reductions in greenhouse gas emissions and the promotion of sustainable waste management practices. Additionally, we explore the promising outcomes of integrating SMS into animal feed formulations, which have demonstrated significant enhancements in livestock growth performance and overall health. In sum, this review underscores the versatility and untapped potential of SMS as a valuable agricultural resource, with a particular focus on its role in advancing sustainable practices, optimizing nutrient management, and harnessing the value of organic waste materials, especially in the context of poultry production.

Thermal Behavior and Pyrolysis Kinetics of Mushroom Residue with the Introduction of Waste Plastics

Co-pyrolysis is considered a very promising technology for the treatment of solid wastes as it can rapidly realize the volume reduction of raw materials and obtain high value-added products. To realize the resource utilization of newly emerging solid wastes in relation to edible fungi residue and waste plastics, mushroom residue (MR), a representative of edible fungi residue, was co-pyrolyzed with waste plastic bags (PE), waste plastic lunch boxes (PP), and waste plastic bottles (PET). The thermal behavior and pyrolysis kinetics of the mixtures were investigated. It was found that the softening of the plastics in the mixtures led to an increase in the initial pyrolysis temperature of MR by 2-27 °C, while the pyrolytic intermediates of MR could greatly promote the decomposition of the plastics, resulting in a decrease in the initial pyrolysis temperatures of PE, PP, and PET in the mixtures by 25, 8, and 16 °C, respectively. The mixture of MR and PE (MR/PE) under different mixture ratios showed good synergies, causing the pyrolysis peaks attributed to MR and PE to both move towards the lower temperature region relative to those of individual samples. The increase in heating rate led to enhanced thermal hysteresis of the reaction between MR and PE. The strength of the interaction between plastics and MR based on mass variation was subject to the order PE > PP > PET. The pyrolysis activation energies of MR, PE, PP, and PET calculated from kinetic analysis were 6.18, 119.05, 84.30, and 74.38 kJ/mol, respectively. The activation energies assigned to MR and plastics were both reduced as plastics were introduced to co-pyrolyze with MR, indicating that MR and plastics have a good interaction in the co-pyrolysis process. This study provides theoretical and experimental guidance for the resource utilization of agricultural solid wastes via thermochemical conversion.

A Further Step toward Sustainable Development: The Case of the Edible Mushroom Supply Chain

This study provides an accurate economic characterization of the supply of edible mushrooms throughout Italy within the European context to fill the relevant research gap and highlight barriers and opportunities that are consistent with the Sustainable Development Goals. Italian companies operating in this field were identified and economically characterized using the Chamber of Commerce's Register of Companies. A qualitative web content analysis was then conducted to extract information about the marketed products, mushroom species, and retail channels, as well as the adopted certifications. The obtained data were quantitatively analyzed through descriptive statistics and multiple correspondence analysis. The Italian market is concentrated in northern areas of the country, and the limited company size indicates fragmentation at the production level, which led to Italy not being competitive enough and, thus, heavily rely on imports. Production is limited to less than 10 species, and innovative mushroom-based products, such as burgers, have shown a limited presence on the market, although they are gaining market share online. The novelty of growing kits highlights the potential to use food production waste to create fungal substrates. Investments in training new mushroom growers and studying new formulations and new fungal species are needed; these investments could allow greater market differentiation and be a good opportunity to promote local economies and create new job opportunities, thus meeting the requirements for sustainable development.

Biochar immobilized plant growth-promoting rhizobacteria enhanced the physicochemical properties, agronomic characters and microbial communities during lettuce seedling

Spent mushroom substrate (SMS) is the by-products of mushroom production, which is mainly composed of disintegrated lignocellulosic biomass, mushroom mycelia and some minerals. The huge output and the lack of effective utilization methods make SMS becoming a serious environmental problem. In order to improve the application of SMS and SMS derived biochar (SBC), composted SMS (CSMS), SBC, combined plant growth-promoting rhizobacteria (PGPR, Bacillus subtilis BUABN-01 and Arthrobacter pascens BUAYN-122) and SBC immobilized PGPR (BCP) were applied in the lettuce seedling. Seven substrate treatments were used, including (1) CK, commercial control; (2) T1, CSMS based blank control; (3) T2, T1 with combined PGPR (9:1, v/v); (4) T3, T1 with SBC (19:1, v/v); (5) T4, T1 with SBC (9:1, v/v); (6) T5, T1 with BCP (19:1, v/v); (7) T6, T1 with BCP (9:1, v/v). The physicochemical properties of substrate, agronomic and physicochemical properties of lettuce and rhizospheric bacterial and fungal communities were investigated. The addition of SBC and BCP significantly (p < 0.05) improved the total nitrogen and available potassium content. The 5% (v/v) BCP addiction treatment (T5) represented the highest fresh weight of aboveground and underground, leave number, chlorophyll content and leaf anthocyanin content, and the lowest root malondialdehyde content. Moreover, high throughput sequencing revealed that the biochar immobilization enhanced the adaptability of PGPR. The addition of PGPR, SBC and BCP significantly enriched the unique bacterial biomarkers. The co-occurrence network analysis revealed that 5% BCP greatly increased the network complexity of rhizospheric microorganisms and improved the correlations of the two PGPR with other microorganisms. Furthermore, microbial functional prediction indicated that BCP enhanced the nutrient transport of rhizospheric microorganisms. This study showed the BCP can increase the agronomic properties of lettuce and improve the rhizospheric microbial community.

Role of minerals in mushroom residue on its adsorption capability to Cd(II) from aqueous solution

To explore the influence of mineral components in bio-sorbent on its adsorption capability towards heavy metal ions, the physicochemical properties of original mushroom residue (UMR) and that treated by an acid solution to remove its minerals (AMR) were comparatively analyzed using inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and fourier transform infrared spectrometer (FT-IR). Then, the adsorption performance of UMR and AMR for Cd(II) as well as the potential adsorption mechanism were investigated. Results show that UMR contains abundant K, Na, Ca and Mg, with the contents of 245.35, 50.18, 1390.63 and 29.84 mmol kg^-1, respectively. Acid treatment (AMR) results in the removal of most of the mineral components, exposing more pore structures and increasing the specific surface area by about 7 times to 20.45 m² g^-1. The adsorption performance of UMR is significantly better than that of AMR when they are employed to purify a Cd(II)-contained aqueous solution. The theoretical maximum adsorption capacity of UMR calculated by Langmuir model is 75.74 mg g^-1, which is about 22 times of that of AMR. Moreover, the adsorption of Cd(II) on UMR reaches an equilibrium at about 0.5 h, while the adsorption equilibrium of AMR takes more than 2 h. The mechanism analysis shows that 86.41% of the adsorption of Cd(II) on UMR can be attributed to ion exchange and precipitation caused by mineral components (especially for K, Na, Ca and Mg). The adsorption of Cd(II) on AMR mainly depends on the interactions between Cd(II) and surface functional groups, electrostatic interaction and pore-filling. The study indicates that those bio-solid wastes with abundant mineral components can be potentially developed as low-cost and high-efficient adsorbents for the removal of heavy metal ions from aqueous solution.

Biosorption of methylene blue by residue from Lentinus crinitus mushroom cultivation

Conventional textile effluent treatments cannot remove methylene blue, a mutagenic azo dye, and an endocrine disruptor, that remains in the drinking water after conventional water treatment. However, the spent substrate from Lentinus crinitus mushroom cultivation, a waste, could be an attractive alternative to remove persistent azo dyes in water. The objective of this study was to assess the methylene blue biosorption by spent substrate from L. crinitus mushroom cultivation. The spent substrate obtained after mushroom cultivation had been characterized by the point of zero charge, functional groups, thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy. Moreover, the spent substrate biosorption capacity was determined in function of pH, time, and temperature. The spent substrate had a point of zero charge value of 4.3 and biosorbed 99% of methylene blue in pH from 3 to 9, with the highest biosorption in the kinetic assay of 15.92 mg g^- 1, and in the isothermal assay of 120.31 mg g^- 1. Biosorption reached equilibrium at 40 min after mixing and best fitted the pseudo-second-order model. Freundlich model best fitted the isothermal parameters and each 100 g spent substrate biosorbed 12 g dye in an aqueous solution. The spent substrate of L. crinitus cultivation is an effective biosorbent of methylene blue and an alternative to removing this dye from water, adding value to the mushroom production chain, and supporting the circular economy.

Spent Mushroom Substrate Hydrolysis and Utilization as Potential Alternative Feedstock for Anaerobic Co-Digestion

Valorization of lignocellulosic biomass, such as Spent Mushroom Substrate (SMS), as an alternative substrate for biogas production could meet the increasing demand for energy. In view of this, the present study aimed at the biotechnological valorization of SMS for biogas production. In the first part of the study, two SMS chemical pretreatment processes were investigated and subsequently combined with thermal treatment of the mentioned waste streams. The acidic chemical hydrolysate derived from the hydrothermal treatment, which yielded in the highest concentration of free sugars (≈36 g/100 g dry SMS, hydrolysis yield ≈75% w/w of holocellulose), was used as a potential feedstock for biomethane production in a laboratory bench-scale improvised digester, and 52 L biogas/kg of volatile solids (VS) containing 65% methane were produced in a 15-day trial of anaerobic digestion. As regards the alkaline hydrolysate, it was like a pulp due to the lignocellulosic matrix disruption, without releasing additional sugars, and the biogas production was delayed for several days. The biogas yield value was 37 L/kg VS, and the methane content was 62%. Based on these results, it can be concluded that SMS can be valorized as an alternative medium employed for anaerobic digestion when pretreated with both chemical and hydrothermal hydrolysis.

Extraction and utilization of active substances from edible fungi substrate and residue: A review

The expansion of the edible fungi industry has resulted in the production of large amounts of edible fungus residues, causing great pressure on environmental protection.Therefore, research on edible fungus residue utilization has become a controversial issue. Thus far, numerous efforts have been devoted to separate active substances from edible fungus substrates and residues for high application value utilization. Building upon this, the main methods for extracting active substances from edible mushroom residues are reviewed, and the mechanisms, influencing factors, and trade-offs of the various methods are analysed. Furthermore, the existing and possible directions of utilization of the extracted active substances are reviewed and discussed. Finally, challenges and prospects for the extraction and utilization of different substances in edible fungus residues are proposed. This review provides an effective strategy for protecting the ecological environment and promoting the sustainable development of human society.

Valorization of spent mushroom substrate for low-carbon biofuel production: Recent advances and developments

Due to the nutritional values and functional bioactivities of mushrooms, the global market value of the edible mushroom industry has been growing steadily. However, the production of 1 kg of fresh mushroom generates about 5 kg of wet byproducts (known as spent mushroom substrate; SMS). This necessitates proper waste management to mitigate potential environmental threats. Embracing the "waste-to-fuel" concept, SMS as lignocellulosic waste can serve as cheap and abundant feedstock for the production of a variety of biofuels, including biogas, biohydrogen, bioethanol, bio-oil, and solid-biofuels. Mushroom cultivation serves as efficient biological pretreatment for biofuel production, promoting biofuel yield and improving the overall economy. Therefore, integrated mushroom cultivation and biofuel production can simultaneously satisfy the rapidly rising food and energy demand. The article systematically reviewed the recycling and re-utilization of SMS in sustainable biofuel production, discussing the possible challenges and proposing future directions for the green development of the mushroom industry.

Valorization of spent mushroom substrate in combination with agro-residues to improve the nutrient and phytohormone contents of vermicompost

In recent years, enormous amounts of spent mushroom substrate (SMS) have been generated because of the rapid development of mushroom production. Since the conventional disposal methods of these residues can cause serious environmental problems, alternative waste management techniques are required to ensure sustainable agriculture. However, SMS might be not suitable for vermicomposting when used alone. Therefore, the primary purpose of this study was to investigate the effect of Azolla microphylla (Azolla) biomass, eggshells, fruit peels, and cassava pulp on the biodegradation process of SMS. The results showed the treatments supplemented with cassava pulp and fruit peel waste improved the growth of earthworms, while the carbon-to-nitrogen ratio of these vermicomposts decreased significantly (p < 0.05) due to the improved total nitrogen contents (7.64 g kg^-1 and 6.71 g kg^-1). Concerning the degradation process and the vermicompost quality, the addition of these agro-residues facilitated the enzyme activities (cellulase, urease, and alkaline phosphatase) and increased the total macronutrient (P, K, Mg, and Ca) and phytohormone (fruit peel waste: AA, GA3, and cytokinin; cassava pulp: cytokinin) contents of the final products compared to the control treatment. On the other hand, Azolla had no additional effect on the fecundity and growth of Eudrilus eugenia. Meanwhile, the treatment supplemented with eggshells was high in Mg (7.15 g kg^-1) and Ca (305.6 g kg^-1). Overall, the combined decomposition of SMS-based bedding material with Azolla, eggshells, fruit peel waste, and cassava pulp resulted in mature organic fertilizers with improved chemical properties.

Effects of Agricultural Management of Spent Mushroom Waste on Phytotoxicity and Microbiological Transformations of C, P, and S in Soil and Their Consequences for the Greenhouse Effect

The huge volumes of currently generated agricultural waste pose a challenge to the economy of the 21st century. One of the directions for their reuse may be as fertilizer. Spent mushroom substrate (SMS) could become an alternative to manure (M). A three-year field experiment was carried out, in which the purpose was to test and compare the effect of SMS alone, as well as in multiple variants with mineral fertilization, and in manure with a variety of soil quality indices-such as enzymatic activity, soil phytotoxicity, and greenhouse gas emissions, i.e., CO₂. The use of SMS resulted in significant stimulation of respiratory and dehydrogenase activity. Inhibition of acid phosphatase and arylsulfatase activity via SMS was recorded. SMS showed varying effects on soil phytotoxicity, dependent on time. A positive effect was noted for the growth index (GI), while inhibition of root growth was observed in the first two years of the experiment. The effect of M on soil respiratory and dehydrogenase activity was significantly weaker compared to SMS. Therefore, M is a safer fertilizer as it does not cause a significant persistent increase in CO₂ emissions. Changes in the phytotoxicity parameters of the soil fertilized with manure, however, showed a similar trend as in the soil fertilized with SMS.

Microflora for improving the Auricularia auricula spent mushroom substrate for Protaetia brevitarsis production

Mushroom cultivation is a sustainable agricultural waste utilization method, but the lack of high-value utilization of the produced spent mushroom substrate (SMS) has hindered the development of mushroom cultivation-based circular agricultural systems. Conversion and utilization of SMS via Protaetia brevitarsis larvae (PBL) have proven to be a high-value AASMS utilization strategy. However, Auricularia auricula SMS (AASMS), which contains woodchips, is less palatable and digestible for PBL. To solve this problem, in this investigation, we screened out microflora (MF) for AASMS fermentation by comparing the fermentation performance as well as the effect on PBL feed intake, weight gain, and AASMS phytotoxic compound removal efficiency. In addition, by bacterial community analysis, the genera Luteimonas, Moheibacter, and Pseudoxanthomonas were predicted to be functional bacteria for AASMS fermentation and contribute to palatability and digestibility improvement.

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Larvae frass microflora can ferment Auricularia auricula spent mushroom substrate

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The fermentation can improve feed intake, weight gain, and phytotoxic removal efficiency

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The genera Luteimonas, Moheibacter, and Pseudoxanthomonas were functional bacteria