Use of spent mushroom compost to bioremediate PAH-contaminated samples

Applying kitchen compost promoted soil chrysene degradation by optimizing microbial community structure

Chrysene, as a high molecular weight polycyclic aromatic hydrocarbon (PAH), has become an important factor in degrading soil quality and constraining the safe production of food crops. Compost has been widely used to amend contaminated soil. However, to date, the main components of kitchen compost that enhance the biodegradation of chrysene in the soil remain unidentified. Thus, in this study, the enhancing effect and mechanisms of kitchen compost (KC) and kitchen compost-derived dissolved organic matter (KCOM) on chrysene removal from soil were investigated through cultivation experiments combined with high-throughput sequencing technology. Additionally, the key components influencing the degradation of chrysene were identified. The results showed that KCOM was the main component of compost that promoted the degradation of chrysene. The average degradation rate of chrysene in 1% KC- and 1% KCOM-treated soil increased by 27.20% and 24.18%, respectively, at different levels of chrysene pollution compared with the control treatment (CK). KC and KCOM significantly increased soil nutrient content, accelerated humification of organic matter, and increased microbial activity in the chrysene-contaminated soil. Correlation analyses revealed that the application of KC and KCOM optimized the microbial community by altering soil properties and organic matter structure. This optimization enhanced the degradation of soil chrysene by increasing the abundance of chrysene-degrading functional bacteria from the genera Bacillus, Arthrobacter, Pseudomonas, Lysinibacillus, and Acinetobacter. This study provides insight into the identification of key components that promote chrysene degradation and into the microbial-enhanced remediation of chrysene-contaminated soil.

A cascade approach to sustainable agriculture: From mushroom mycelium to lettuce harvest

Sustainable agriculture involves adopting best practices in food production to promote environmental and economic sustainability. Its implementation primarily aims to utilise organic residues to increase yield, diversify production, and reduce costs. In this context, the objective of this study was to investigate different substrates for Hypsizygus ulmarius production and, from its residual substrate, to develop formulations for lettuce seedling growth and subsequent greenhouse cultivation. For mushroom production, substrates were prepared from sawdust with the addition of wheat bran, rice bran, soybean meal, and calcite, resulting in four distinct substrate formulations. The spent mushroom substrate (SMS), obtained at the end of cultivation, was used for lettuce seedling production along with the commercial substrate Carolina Soil® and the soil conditioner BacSol®. The top five formulations were selected for transplanting in the greenhouse. Regarding mushroom production, substrates with higher carbon/nitrogen ratios, around 66: 1, resulted in higher yields. For seedling production, SMS showed lower efficiency compared to the commercial substrate Carolina Soil®, which also benefited from the addition of the soil conditioner BacSol®. However, after transplanting lettuce seedlings, the formulation containing SMS showed superior results in almost all evaluated parameters. Therefore, we concluded that despite the inefficiency of using H.ulmarius SMS for lettuce seedling production, it favours the establishment of seedlings in greenhouse cultivation environments.

Bioremediation of petroleum hydrocarbons polluted soil by spent mushroom substrates: Microbiological structure and functionality

Spent mushroom substrate (SMS) holds valuable microbiota that can be useful in remediating polluted soils with hydrocarbons. However, the microorganisms behind the bioremediation process remain uncertain. In this work, a bioremediation assay of total petroleum hydrocarbons (TPHs) polluted soil by SMS application was performed to elucidate the microorganisms and consortia involved in biodegradation by a metabarcoding analysis. Untreated polluted soil was compared to seven bioremediation treatments by adding SMS of Agaricus bisporus, Pleurotus eryngii, Pleurotus ostreatus, and combinations. Soil microbial activity, TPH biodegradation, taxonomic classification, and predictive functional analysis were evaluated in the microbiopiles at 60 days. Different metagenomics approaches were performed to understand the impact of each SMS on native soil microbiota and TPHs biodegradation. All SMSs enhanced the degradation of aliphatic and aromatic hydrocarbons, being A. bisporus the most effective, promoting an efficient consortium constituted by the bacterial families Alcanivoraceae, Alcaligenaceae, and Dietziaceae along with the fungal genera Scedosporium and Aspergillus. The predictive 16 S rRNA gene study partially explained the decontamination efficacy by observing changes in the taxonomic structure of bacteria and fungi, and changes in the potential profiles of estimated degradative genes across the different treatments. This work provides new insights into TPHs bioremediation.

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.

Bioremediation of polycyclic aromatic hydrocarbons: An updated microbiological review

A class of organic priority pollutants known as PAHs is of critical public health and environmental concern due to its carcinogenic properties as well as its genotoxic, mutagenic, and cytotoxic properties. Research to eliminate PAHs from the environment has increased significantly due to awareness about their negative effects on the environment and human health. Various environmental factors, including nutrients, microorganisms present and their abundance, and the nature and chemical properties of the PAH affect the biodegradation of PAHs. A large spectrum of bacteria, fungi, and algae have ability to degrade PAHs with the biodegradation capacity of bacteria and fungi receiving the most attention. A considerable amount of research has been conducted in the last few decades on analyzing microbial communities for their genomic organization, enzymatic and biochemical properties capable of degrading PAH. While it is true that PAH degrading microorganisms offer potential for recovering damaged ecosystems in a cost-efficient way, new advances are needed to make these microbes more robust and successful at eliminating toxic chemicals. By optimizing some factors like adsorption, bioavailability and mass transfer of PAHs, microorganisms in their natural habitat could be greatly improved to biodegrade PAHs. This review aims to comprehensively discuss the latest findings and address the current wealth of knowledge in the microbial bioremediation of PAHs. Additionally, recent breakthroughs in PAH degradation are discussed in order to facilitate a broader understanding of the bioremediation of PAHs in the environment.

A novel technology of solarization and phytoremediation enhanced with biosurfactant for the sustainable treatment of PAH-contaminated soil

Hydrocarbon-contaminated land has been a significant issue throughout Nigeria's Niger Delta since the discovery of crude oil in 1956. This paper proposes a novel and sustainable technique involving soil solarization, phytoremediation and biosurfactant to treat polycyclic aromatic hydrocarbon (PAH) contamination. The treatment effect on PAH reduction, plant growth, rhizosphere microorganisms and their enzymatic activities was evaluated. Twenty-eight days of solarization was carried out before the introduction of Chromolaena odorata seedlings for an 84-day phytoremediation period using a 4 × 4 (vegetated) and 2 × 4 (non-vegetated) cell microcosms to simulate the Niger Delta's subtropical conditions. Soil solarization resulted in significant PAH reduction (p ≤ 0.01) of phenanthrene, fluoranthene and benzo(a)pyrene with means reduction of 60.0%, 38.7% and 36.1% compared to their non-solarized counterparts with 18.0%, 18.0% and 18.8% at 95% CI (32.7, 51.3), (15.4, 26.1) and (8.0, 26.6), respectively. In post-solarization, all solarized and vegetated treatment groups significantly reduced (p ≤ 0.01) PAHs compared to their respective counterparts, while biosurfactant contribution in this combination was negligible (p ≥ 0.05). The growth parameters of C. odorata, total soil/rhizosphere heterotrophic microorganisms and their enzymatic activities of dehydrogenase and urease increased in all solarized treatments indicating essential biochemical processes. The novel and successful integration of soil solarization and phytoremediation using indigenous C. odorata as a combined technique to treat even the most recalcitrant form of hydrocarbons (PAHs) brings up new opportunities for a sustainable method of cleaning up contaminated land in Nigeria's oil-rich Niger Delta.

Nutrient uptake in supplemented substrate by oyster mushroom

Spent mushroom substrate (SMS) is a promising alternative for supplementing oyster mushroom substrate, replacing conventional cereal bran. Therefore, the objective was to evaluate the production of Pleurotus ostreatus supplemented with Lentinula edodes' SMS, through the nutritional analysis of the substrate. Wheat straw was used as substrate and supplemented with rice bran (RB) or SMS in 0%, 7%,15% and 30%. Ca, K, Mg, Mn, Zn, Cu and Fe contents of the cultivation substrates (before and after harvest) were determined through atomic absorption spectrophotometry. Mycelial growth (cm²/day), mycelial time colonization (days), number of clusters, number of pileus, average clusters weight (g), pileus lenght (cm) and width (cm), productivity (1st, 2nd and 3rd flush) (%), biological efficiency (%) of mushrooms were evaluated. Results indicated mycelial growth was higher (0.87 cm²/day compared to the Control) when the substrate was supplemented regardless of the source. The proportions of 15% of SMS achieved the highest biological efficiency (107% - 15% SMS versus 66% - Control). The only nutrients that showed differences in absorption were Ca, K and Mn, in which substrates supplemented with SMS had greater absorption of Ca (5.37 g.kg^- 1 versus 1.94 g.kg^- 1 in Control) while substrates supplemented with RB absorbed more K (6.56 g.kg^- 1 versus 3.74 g.kg^- 1 in Control). The mineral composition of the substrate has a direct impact on the growth and yield of P. ostreatus, highlighting the potential of SMS as a alternative to traditional bran supplementation.

Optimization of laccase enzyme extraction from spent mushroom waste of Pleurotus florida through ANN-PSO modeling: An ecofriendly and economical approach

The cardinal focus of this study is to optimize the best reaction conditions for maximizing laccase activity from spent mushroom waste (SMW) of Pleurotus florida. Optimization process parameters were studied by the modeling techniques, artificial neural networking (ANN) embedded in particle swarm optimization (PSO), and response surface model (RSM). The best topology of ANN-PSO architecture was obtained on 4-10-1. The R², IOA, MSE, and MAE values of the ANN model were obtained as 0.98785, 0.9939, 0.0023, and 0.0251 while, that of the RSM model were obtained as 0.74290, 0.9210, 0.0244, and 0.1110 respectively. The higher values of R², IOA, and lower values of MSE and MAE of the ANN-PSO model depict that ANN-PSO outperformed compared to RSM and also verified the effectiveness of the ANN-PSO model. The ANN-PSO model performance demonstrates the robustness of the technique in optimizing laccase activity in SMW of P. florida. The optimization results revealed that pH 4.5, time 3 h, solid: solution ratio 1:5, and ABTS concentration of 1 mM was optimal for achieving maximum laccase activity at temperature 30 °C. The enzymatic activity of crude laccase enzyme was obtained as 1.185 U ml^-1 without loss of enzyme activity. Additionally, crude laccase enzyme was 1.74 fold partially purified, and 83.54% of the enzyme was yielded. Out of all the independent process variables, ABTS and pH had an influence on laccase activity. Therefore, we anticipate that the findings of this investigation will reduce the ambiguity in maximizing laccase activity and ease the screening process. This study also highlights the comparative cost evaluation of crude laccase enzyme extracted from P. florida and commercial enzymes. There is a great potential for the utilization of the laccase enzyme extracted from SMW and using it for the degradation of recalcitrant micropollutants. Thus, SMW promises a cost-effective and sustainable approach leading towards circular economy.

Fermentation Quality, In Vitro Digestibility, and Aerobic Stability of Ensiling Spent Mushroom Substrate with Microbial Additives

This experiment investigated the effects of lactic acid bacteria and cellulase on the fermentation quality, in vitro digestibility, and aerobic stability of Flammulina velutipes spent mushroom substrate silage (F-silage) and Pleurotus eryngii spent mushroom substrate silage (P-silage). Silage treatments included groups without any additives (control), with lactic acid bacteria (L), with cellulase (E), and with lactic acid bacteria and cellulase (M). Data analysis was performed using independent sample t-test and analysis of variance. After 45 days of ensiling, the pH in F-silage and P-silage from the L, E, and M groups were lower than those in the control group (p < 0.05). The pH, acetic acid (AA), and propionic acid (PA) levels in P-silage were lower than those in F-silage, and the LA content in P-silage was higher than that in F-silage (p < 0.05). Compared with the control, the E treatment increased in vitro neutral detergent fibre digestibility (IVNDFD) and in vitro acid detergent fibre digestibility (IVADFD) in F-silage and P-silage (p < 0.05). The aerobic stability of F-silage inoculated with L increased (p < 0.05) by 24 h compared to the control. The aerobic stability of P-silage inoculated with M increased (p < 0.05) by 6 h compared to the control. The improvement in fermentation quality and aerobic stability is extremely large in terms of applying M in F-silage and P-silage. The E is effective in improving the in vitro digestibility of P-silage. The research results provide a theoretical basis for the production of high-quality spent mushroom substrate fermented feed.

Organic amendment treatments for antimicrobial resistance and mobile element genes risk reduction in soil-crop systems

Agricultural fertilization with organic amendments of animal origin often leads to antibiotic resistance dissemination. In this study, we evaluated the effect of different treatments (anaerobic digestion, biochar application, ozonation, zerovalent iron nanoparticle application, and spent mushroom substrate addition) on the resistome in dairy cow manure-derived amendments (slurry, manure, and compost). Anaerobic digestion and biochar application resulted in the highest reduction in antibiotic resistance gene (ARG) and mobile genetic element (MGE) gene abundance. These two treatments were applied to cow manure compost, which was then used to fertilize the soil for lettuce growth. After crop harvest, ARG and MGE gene absolute and relative abundances in the soil and lettuce samples were determined by droplet digital PCR and high-throughput qPCR, respectively. Prokaryotic diversity in cow manure-amended soils was determined using 16S rRNA metabarcoding. Compared to untreated compost, anaerobic digestion led to a 38% and 83% reduction in sul2 and intl1 absolute abundances in the soil, respectively, while biochar led to a 60% reduction in intl1 absolute abundance. No differences in lettuce gene abundances were observed among treatments. We conclude that amendment treatments can minimize the risk of antibiotic resistance in agroecosystems.

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.

Fate of antibiotic resistance genes in cultivation substrate and its association with bacterial communities throughout commercial production of Agaricus bisporus

Animal manure is an important raw material for Agaricus bisporus production; however, it is also a reservoir for antibiotic residues, antibiotic resistance genes (ARGs), and antibiotic-resistant bacteria. Little is known about the influence of the commercial cultivation of A. bisporus on the dynamics of ARGs and the underlying mechanisms that cause their variations. In this study, we investigated the fate of 285 ARGs, 10 mobile genetic elements, and seven major categories of antibiotic residues in substrate and mushroom samples at different production phases. The results showed that commercial substrate preparation, particularly the pasteurization phase, was highly efficient in removing ARGs from the substrate. We further found that mycelium proliferation of A. bisporus contributed significantly to the removal of ARGs from the substrate and casing soil. The bacterial community is the key driver of changes in ARGs during the commercial cultivation of A. bisporus, which explained 46.67% of the variation in ARGs. Our results indicate that, despite the addition of animal manure, the risk of ARG dissemination to fruiting bodies and the environment is low. We propose that bioremediation by specific edible fungi might be a novel and promising method for scavenging antimicrobial resistance contamination from soil environment.

Spent waste from edible mushrooms offers innovative strategies for the remediation of persistent organic micropollutants: A review

Urgent and innovative strategies for removal of persistent organic micropollutants (OMPs) in soil, groundwater, and surface water are the need of the hour. OMPs detected in contaminated soils and effluents from wastewater treatment plants (WWTPs) are categorized as environmentally persistent pharmaceutical pollutants (EPPPs), and endocrine disrupting chemicals (EDCs), their admixture could cause serious ecological issues to the non-target species. As complete eradication of OMPs is not possible with the extant conventional WWTPs technology, the inordinate and reckless application of OMPs negatively impacts environmental regenerative and resilience capacity. Therefore, the cardinal focus of this review is the bioremediation of persistent OMPs through efficient application of an agro-waste, i.e. spent mushroom waste (SMW). This innovative, green, long-term strategy embedded in the circular economy, based on state of the art information is comprehensively assessed in this paper. SMW accrues ligninolytic enzymes such as laccase and peroxidase, with efficient mechanism to facilitate biodegradation of recalcitrant organic pollutants. It is vital in this context that future research should address immobilization of such enzymes to overcome quantitative and qualitative issues obstructing their widespread use in biodegradation. Therefore, dual benefit is gained from cultivating critical cash crops like mushrooms to meet the escalating demand for food resources and to aid in biodegradation. Hence, mushroom cultivation has positive environmental, social, and economic implications in developing countries like India.

Insights into the Applications of Extracellular Laccase-Aided Humification in Livestock Manure Composting

Traditional composting is a well-suited biotechnology for on-farm management of livestock manure (LM) but still leads to the release of toxic micropollutants and imbalance of nutrients. One in situ exoenzyme-assisted composting has shown promise to ameliorate the agronomical quality of end products by improving humification and polymerization. The naturally occurring extracellular laccase from microorganisms belongs to a multicopper phenoloxidase, which is verified for its versatility to tackle micropollutants and conserve organics through the reactive radical-enabled decomposition and polymerization channels. Laccase possesses an indispensable relationship with humus formation during LM composting, but its potential applications for the harmless disposal and resource utilization of LM have until now been overlooked. Herein, we review the extracellular laccase-aided humification mechanism and its optimizing strategy to maintain enzyme activity and in situ production, highlighting the critical roles of laccase in treating micropollutants and preserving organics during LM composting. Particularly, the functional effects of the formed humification products by laccase-amended composting on plant growth are also discussed. Finally, the future perspectives and outstanding questions are summarized. This critical review provides fundamental insights into laccase-boosted humification that ameliorates the quality of end products in LM composting, which is beneficial to guide and advance the practical applications of exoenzyme in humification remediation, the carbon cycle, and agriculture protection.

Petroleum-contaminated soil: environmental occurrence and remediation strategies

Soil is an environmental matrix that carries life for all living things. With the rise of human activities and the acceleration of population, the soil has been exposed in part to pollution by the discharge of various xenobiotics and persistent pollutants into it. The disposal of toxic substances such as polycyclic aromatic hydrocarbons (PAHs) alters soil properties, affects microbial biodiversity, and damages objects. Considering the mutagenicity, carcinogenicity, and toxicity of petroleum hydrocarbons, the restoration and clean-up of PAH-polluted sites represents an important technological and environmental challenge for sustainable growth and development. Though several treatment methods to remediate PAH-polluted soils exist, interesting bacteria, fungi, and their enzymes receive considerable attention. The aim of the present review is to discuss PAHs' impact on soil properties. Also, this review illustrates physicochemical and biological remediation strategies for treating PAH-contaminated soil. The degradation pathways and contributing factors of microbial PAH-degradation are elucidated. This review also assesses the use of conventional microbial remediation compared to the application of genetically engineered microorganisms (GEM) that can provide a cost-effective and eco-friendly PAH-bioremediation strategy.

Biochar from fungiculture waste for adsorption of endocrine disruptors in water

The agricultural residues are ecofriendly alternatives for removing contaminants from water. In this way, a novel biochar from the spent mushroom substrate (SMS) was produced and assessed to remove endocrine disruptor from water in batch and fixed-bed method. SMS were dried, ground, and pyrolyzed. Pyrolysis was carried out in three different conditions at 250 and 450 °C, with a residence time of 1 h, and at 600 °C with a residence time of 20 min. The biochar was firstly tested in a pilot batch with 17α-ethinylestradiol (EE2) and progesterone. The residual concentrations of the endocrine disruptors were determined by HPLC. The biochar obtained at 600 °C showed the best removal efficiency results. Then, adsorption parameters (isotherm and kinetics), fixed bed tests and biochar characterization were carried out. The Langmuir model fits better to progesterone while the Freundlich model fits better to EE2. The Langmuir model isotherm indicated a maximum adsorption capacity of 232.64 mg progesterone/g biochar, and 138.98 mg EE2/g biochar. Images from scanning electrons microscopy showed that the 600 °C biochar presented higher porosity than others. In the fixed bed test the removal capacity was more than 80% for both endocrine disruptors. Thus, the biochar showed a good and viable option for removal of contaminants, such as hormones.

Growth Performance and Hematological Changes in Growing Sika Deers Fed with Spent Mushroom Substrate of Pleurotus ostreatus

Simple Summary

With the rapid development of the mushroom industry, a large number of spent mushroom substrate (SMS) has also been produced. SMS can be easily digested by ruminants and is suitable for feeding animals, such as cows, sheep, as well as deer. The results of this study show that the dietary spent mushroom substrate of Pleurotus ostreatus (SMS-MP) has no obvious effect on the physiological condition of growing sika deer, at the same time it can reduce the cost of feeding and avoid environmental pollution caused by improper disposal of SMS-MP.

Abstract

The purpose of this experiment is to expand the feed of growing sika deer and to explore the effects on growing sika deer of the spent mushroom substrate of Pleurotus ostreatus (SMS-MP). Twelve immature female growing sika deer were randomly assigned to four groups. The ratios of SMS-MP to replace concentration supplements were 0%, 10%, 20%, and 30%, respectively, and the growth performance, feed intake and apparent digestibility, serum biochemical indexes, blood physiological indexes, serum immune globulin and plasma amino acid of growing sika deer were measured. The results of the current study confirmed the applicability of SMS-MP as a feed ingredient in growing sika deer diets. There was no significant change in growth performance and hematology of growing sika deer when the concentrate supplement was replaced with 10–20% SMS-MP. However, replacing 30% of concentrate supplements with SMS-MP in the growing sika deer diet resulted in significantly decreased Hb and HCT levels. It can be concluded that, as a waste resource, adding a small amount of SMS-MP has no significant effect on the growth of sika deer, and at the same time can reduce the consumption of concentrate supplements, thereby improving the economic benefits of sika deer breeding.

Polycyclic aromatic hydrocarbon contamination in soils and sediments: Sustainable approaches for extraction and remediation

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic environmental pollutants that are extremely hydrophobic in nature and resistant to biological degradation. Extraction of PAHs from environmental matrices is the first and most crucial step in PAH quantification. Extraction followed by quantification is essential to understand the extent of contamination prior to the application of remediation approaches. Due to their non-polar structures, PAHs can be adsorbed tightly to the organic matter in soils and sediments, making them more difficult to be extracted. Extraction of PAHs can be achieved by a variety of methods. Techniques such as supercritical and subcritical fluid extraction, microwave-assisted solvent extraction, plant oil-assisted extraction and some microextraction techniques provide faster PAH extraction using less organic solvents, while providing a more environmentally friendly and safer process with minimum matrix interferences. More recently, more environmentally friendly methods for soil and sediment remediation have been explored. This often involves using natural chemicals, such as biosurfactants, to solubilize PAHs in contaminated soils and sediments to allow subsequent microbial degradation. Vermiremediation and microbial enzyme-mediated remediation are emerging approaches, which require further development. The following summarises the existing literature on traditional PAH extraction and bioremediation methods and contrasts them to newer, more environmentally friendly ways.

Profile of atmospheric particulate PAHs near busy roadway in tropical megacity, India

Objective: This study focuses on the profile of ambient particulate polycyclic aromatic hydrocarbons (PAHs), their seasonal distribution, source identification and human health risk assessment due to inhalation exposure of ambient PAHs in Delhi, India.Materials and Methods: Two sampling sites were chosen, one at roadway (MH) and other at urban background (JNU) site in Delhi. Determination of PAHs was carried with the help of HPLC with UV detector. Principal component analysis and Molecular diagnostic ratios were used for the source apportionment of PAHs. Health risks associated with inhalation of particulate PAHs were assessed using benzo(a)pyrene equivalent concentration and incremental lifetime cancer risk (ILCR) approach.Results: The results showed that the average mass concentration of Σ₁₆ PAHs near roadway (67.8 ± 40.2 ng m^-3) is significantly higher than urban background site (56 ± 30 ng m^-3). Moreover, source apportionment study indicated that major PAH-emission sources in Delhi NCR are traffic and coal combustion. ILCR values at both the sites fall in the range of 10^-2-10^-4 that corresponds to the priority risk level (10^-3) and higher than the acceptable risk level (10^-6).conclusions: The high PAHs concentration at MH site was due to it's nearness to busy traffic area. Thus, the spatial variations in PAHs were influenced by local emission sources. The high PAHs level during the winter season can be due to their higher emissions from local heating sources, shift of gas/particle partitioning toward the particulate phase at low temperature and reduced photochemical degradation of some PAHs in winter. The low level of PAHs in monsoon season can be attributed to their wet scavenging and higher percentage in vapor phase. PCA showed that the emissions from vehicles predominate at MH site; whereas, coal combustion and traffic both are the significant PAHs sources at JNU site. Health risk assessment revealed that the highest exposure risks occur at busy traffic site, thereby indicating a significantly higher health risk to the population of Delhi.

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

Commercial mushrooms are cultivated on lignocellulose wastes, such as corncob, saw dust, straw and wood chips. Following the rapidly increasing global mushroom production, the efficient recycling and utilization of the by-product, known as spent mushroom substrate (SMS) has garnered much attention due to the serious pollution issues caused. Embracing the concept of 'circular economy', the SMSs have demonstrated immense potential in wide range of applications, including recycling as the substrate for new cultivation cycle of mushroom, biofertilizer and soil amendment, animal feed, renewable energy production and pollution bioremediation. The review provided an overview and recent advances focusing on these applications, analyzed the possible challenges and proposed future directions for sustainable development of global mushroom industry.

Application of Fungus Enzymes in Spent Mushroom Composts from Edible Mushroom Cultivation for Phthalate Removal

Spent mushroom composts (SMCs) are waste products of mushroom cultivation. The handling of large amounts of SMCs has become an important environmental issue. Phthalates are plasticizers which are widely distributed in the environment and urban wastewater, and cannot be effectively removed by conventional wastewater treatment methods. In this study, SMCs are tested for their ability to remove phthalates, including benzyl butyl phthalate (BBP), di-n-butyl phthalate (DBP), and diethyl phthalate (DEP). Batch experiments reveal that BBP, DBP, and DEP can be degraded by the SMC enzyme extracts of four edible mushrooms: Pleurotus eryngii, Pleurotus djamor, Pleurotus ostreatus, and Auricularia polytricha. Potential fungus enzymes associated with BBP, DBP, and DEP degradation in SMCs (i.e., esterases, oxygenases, and oxidases/dehydrogenases) are uncovered by metaproteomic analysis using mass spectrometry. Bioreactor experiments indicate that the direct application of SMCs can remove BBP, DBP, and DEP from wastewater, through adsorption and biodegradation. The results of this study extend the application of white-rot fungi without laccases (e.g., Auricularia sp.) for the removal of organic pollutants which are not degraded by laccases. The application of SMCs for phthalate removal can be developed into a mycoremediation-based green and sustainable technology.

Effects of Application of Recycled Chicken Manure and Spent Mushroom Substrate on Organic Matter, Acidity, and Hydraulic Properties of Sandy Soils

Soil organic matter is a key resource base for agriculture. However, its content in cultivated soils is low and often decreases. This study aimed at examining the effects of long-term application of chicken manure (CM) and spent mushroom substrate (SMS) on organic matter accumulation, acidity, and hydraulic properties of soil. Two podzol soils with sandy texture in Podlasie Region (Poland) were enriched with recycled CM (10 Mg ha⁻¹) and SMS (20 Mg ha⁻¹), respectively, every 1–2 years for 20 years. The application of CM and SMS increased soil organic matter content at the depths of 0–20, 20–40, and 40–60 cm, especially at 0–20 cm (by 102–201%). The initial soil pH increased in the CM- and SMS-amended soil by 1.7–2.0 units and 1.0–1.2 units, respectively. Soil bulk density at comparable depths increased and decreased following the addition of CM and SMS, respectively. The addition of CM increased field water capacity (at –100 hPa) in the range from 45.8 to 117.8% depending on the depth within the 0–60 cm layer. In the case of the SMS addition, the value of the parameter was in the range of 42.4–48.5% at two depths within 0–40 cm. Depending on the depth, CM reduced the content of transmission pores (>50 µm) in the range from 46.3 to 82.3% and increased the level of residual pores (<0.5 µm) by 91.0–198.6%. SMS increased the content of residual pores at the successive depths by 121.8, 251.0, and 30.3% and decreased or increased the content of transmission and storage pores. Additionally, it significantly reduced the saturated hydraulic conductivity at two depths within 0–40 cm. The fitted unsaturated hydraulic conductivity at two depths within the 0–40 cm layer increased and decreased in the CM- and SMS-amended soils, respectively. The results provide a novel insight into the application of recycled organic materials to sequester soil organic matter and improve crop productivity by increasing soil water retention capacity and decreasing acidity. This is of particular importance in the case of the studied low-productivity sandy acidic soils that have to be used in agriculture due to limited global land resources and rising food demand.

A comprehensive feasibility study of effectiveness and environmental impact of PAH bioremediation using an indigenous microbial degrader consortium and a novel strain Stenotrophomonas maltophilia CPHE1 isolated from an industrial polluted soil

Polycyclic Aromatic Hydrocarbons (PAHs) are major toxic and recalcitrant pollutants in the environment. This study assessed the capacity of an isolated soil microbial consortium (OMC) to biodegrade PAHs. OMC was able to reach 100% biodegradation of naphthalene, acenaphthylene, acenaphthene, fluorene and phenanthrene in solution, and up to 76% and 50% of anthracene and fluoranthene, respectively, from a mix of 16 PAHs. To measure phenanthrene (PHE) mineralization, OMC and eight strains isolated from OMC were used and identified by PCR amplification of the gene 16S ribosomal RNA. A novel Stenotrophomonas maltophilia CPHE1, not previously described as a PAH degrader, was able to mineralize almost 40% PHE and biodegrade 90.5% in solution, in comparison to OMC that reached 100% PHE degradation, but only 18.8% mineralization. Based on metabolites identified during PHE degradation and on the detection of two genes (PAH RHDα and nahAc) in OMC consortium, two possible via were described for its degradation, through salicylic and phthalic acid. PAH RHDα, which codified the first step on PHE biodegradation pathway, was also found in the DNA of S. maltophilia CPHE1. An ecotoxicology study showed that PHE bioremediation after inoculating S. maltophilia CPHE1 for 30 days decreased by half the solution toxicity.

Comparative Study on Lead and Copper Biosorption Using Three Bioproducts from Edible Mushrooms Residues

Agricultural waste products can be used as biosorbents for bioremediation once they are low-cost and high-efficient in pollutants removal. Thus, waste products from mushroom farming such as cutting and substrate of Lentinula edodes (popularly known as shiitake) and Agaricus bisporus (also known as champignon) were evaluated as biosorbents for metallic contaminants copper (Cu) and lead (Pb). Shiitake and champignon stalks, and shiitake substrate (medium in which shiitake was cultivated) were dried, grounded, characterized and experimented to remove Cu and Pb from contaminated water. The Sips model was used to establish the adsorption isotherms. Regarding Cu, champignon stalks have the best removal efficiency (43%), followed by substrate and stalks of shiitake (37 and 30%, respectively). Pb removals were similar among three residues (from 72 to 83%), with the champignon stalks standing out. The maximum adsorption capacities (q_max) for Cu in shiitake and champignon stalks were 22.7 and 31.4 mg/g⁻¹, respectively. For Pb, q_max for shiitake and champignon stalks, and shiitake substrate were 130.0, 87.0 and 84.0 mg/g⁻¹, respectively. The surface morphology of the champignon stalks revealed an organized and continuous structure. After an interaction with metals, the stalk of champignon accumulated the metal ions into interstices. Mushroom residues showed a relevant adsorption efficiency, especially for Pb. Mushroom farming waste are a very low-cost and promising alternative for removing toxic heavy metals from aquatic environment.

Rhizosphere assisted bioengineering approaches for the mitigation of petroleum hydrocarbons contamination in soil

The high demand for petroleum oil has led to hydrocarbon contamination in soil, including agricultural lands, and many other ecosystems across the globe. Physical and chemical treatments are effective strategies for the removal of high contamination levels and are useful for small areas, although with concerns of cost-effectiveness. Alternatively, several bacteria belonging to the Phylum: Proteobacteria, Bacteroidetes, Actinobacteria, Nocardioides, or Firmicutes are used for biodegradation of different hydrocarbons - aliphatic, polyaromatic hydrocarbons (PAH), and asphaltenes in the oil-contaminated soil. The rhizoremediation strategy with plant-microbe interactions has prospects to achieve the desired result in the field conditions. However, adequate biostimulation, and bioaugmentation with the suitable plant-microbe combination, and efficiency under a toxic environment needs to be evaluated. Modifying the microbiomes to achieve better biodegradation of contaminants is an upcoming strategy popularly known as microbiome engineering. In this review, rhizoremediation for the successful removal of the hydrocarbons have been critically discussed, with challenges for making it a feasible technology.HIGHLIGHTSPetroleum hydrocarbon contamination has increased around the globe.Rhizoremediation has the potential for the mitigation of pollutants from the contaminated sites.An accurate and detailed analysis of the physio-chemical and climatic conditions of the contaminated sites must be focused on.The suitable plant and bacteria, with other major considerations, may be employed for in-situ remediation.The appropriate data should be obtained using the omics approach to help toward the success of the rhizoremediation strategy.

Composting Spent Mushroom Substrate from Agaricus bisporus and Pleurotus ostreatus Production as a Growing Media Component for Baby Leaf Lettuce Cultivation under Pythium irregulare Biotic Stress

Composts of spent mushrooms substrates can be an alternative for the partial replacement of peat as growing media in horticulture. Three mature composts from Agaricus bisporus (Ag), Pleurotus ostreatus (Pl), and 70% Ag:30% Pl (AgPl) production were used as partial components of peat growing media, used at a 1:4 compost:peat ratio for growing red baby leaf lettuce. They showed higher yields, between 3 and 7 times more than that for peat itself, even under the pressure of the plant pathogen Pythium irregulare. AgPl showed the higher suppressiveness (50%) against Pythium irregulare than Ag- (38%) or Pl- (15%) supplemented media. The combination of these raw materials and a suitable composting process is important for obtaining mature compost for use as a partial component of peat-based growing media.

Spent mushroom substrate: a crucial biosorbent for the removal of ferrous iron from groundwater

Abstract

A new approach was carried out with the spent mushroom substrate (SMS) of Pleurotus florida on ferrous iron (Fe2+) removal using live, dead and pretreated substrate. In this study, the various dosage levels of SMS namely, 0.25, 0.50, 1.0 and 1.50 g/50 mL were used for the removal of Fe2+ at different time intervals for 90 min. The effect of various temperatures and pH on Fe2+ removal was studied with optimized dosages and time intervals. The biosorption potential of P. florida SMS was checked against the iron-contaminated groundwater collected from in and around Salem, Namakkal and Dharmapuri districts of Tamil Nadu. The biosorption data were obtained and analyzed in terms of their kinetic behavior. Among the SMS of P. florida, the live SMS showed potential Fe2+ removal (100%) from aqueous metal solution in all the tested concentrations. SMS of P. florida showed high potential removal of Fe2+ in neutral pH, at room temperature and explored an efficient sorption ability (100%) in the tested water sample (SW10). The adsorption kinetic values fitted very well with pseudo-second-order when comparing with pseudo-first-order reaction. FTIR, SEM and EDX analysis proved the accumulation of Fe2+ by the SMS. The present study confirmed that the live SMS of P. florida may serve as a potential and eco-friendly biosorbent for removal of Fe2+ from the iron-contaminated water.

Graphic abstract

Development of formaldehyde-free bio-board produced from mushroom mycelium and substrate waste

Synthetic adhesives in the plywood industry are usually volatile compounds such as formaldehyde-based chemical which are costly and hazardous to health and the environment. This phenomenon promotes an interest in developing bio-boards without synthetic adhesives. This study proposed a novel application of natural mycelium produced during mushroom cultivation as natural bio-adhesive material that convert spent mushroom substrate (SMS) into high-performance bio-board material. Different types of spent mushroom substrates were compressed with specific designed mould with optimal temperature at 160 °C and 10 mPa for 20 min. The bio-board made from Ganoderma lucidum SMS had the highest internal bonding strength up to 2.51 mPa. This is far above the 0.4-0.8 range of China and US national standards. In addition, the material had high water and fire resistance, high bonding and densified structures despite free of any adhesive chemicals. These properties and the low cost one step procedure show the potential as a zero-waste economy chain for sustainable agricultural practice for waste and remediation.

Antioxidation, anti-hyperlipidaemia and hepatoprotection of polysaccharides from Auricularia auricular residue

As hyperlipidemia was a pathological progress by lipid dysfunctions, the present object was to investigate the hypolipidemic and hepatoprotective effects of Auricularia auricular residue polysaccharides (RPS) against HFE (high-fat emulsion) toxicities in mice. The structure analysis showed that the RPS was pyranose-polysaccharides mainly composed of glucose with the weight-average molecular weight of 2.00 × 10⁵ Da. The in vivo experiments demonstrated that the RPS had potential hepatoprotections by enhancing the antioxidant and anti-hyperlipidaemia status, and could inhibit the increasing body weights. Besides, the RPS could improve the glucose utilization with the oral glucose tolerance test (120 min) of 5.04 ± 0.12 mmol/L at the dose of 400 mg/kg bw. The results in present study demonstrated that RPS could be used as a functional foods and natural medicines against the HFE-induced hyperlipidemia and its complications.

Effects of spent mushroom substrate on the dissipation of polycyclic aromatic hydrocarbons in agricultural soil

Spent mushroom substrate (SMS) is an agricultural waste with a high potential for polycyclic aromatic hydrocarbons (PAH) removal in aged contaminated soils. In this study, fresh and air-dried Pleurotus ostreatus, Pleurotus eryngii, and Auricularia auricular SMSs were used to remove PAHs in agricultural soil under 60-day incubation. The potential of SMS in PAH dissipation was studied by detecting the dissipation rate and the soil physicochemical index, enzyme activity, PAH-degradation bacterial biomass, and microbial diversity. Results showed that SMS significantly enhanced the dissipation of PAHs and fresh SMS had a better effect than air-dried SMS. The highest dissipation rate of 16 PAHs was 34.5%, which was observed in soil amended with fresh P. eryngii SMS, and the PAH dissipation rates with low and high molecular weights were 41.3% and 19.4%, respectively. By comparison, fresh P. eryngii SMS presented high nutrient contents, which promoted the development of PAH-degrading bacteria and changed the soil bacterial community involved in degradation, thereby promoting the PAH dissipation. The lignin-degrading enzymes in fresh SMS were abundant, and the laccase and manganese peroxidase activities in the treatment of fresh P. eryngii SMS was higher than those in other treatments. Fresh P. eryngii SMS improved the relative abundance of Microbacterium, Rhizobium, and Pseudomonas in soil, which were all related to PAH degradation. Consequently, adding fresh P. eryngii SMS was an effective method for remediating aged PAH-contaminated agricultural soils.

Removal of Cd, Pb, Zn, Cu in smelter soil by citric acid leaching

Soil washing has been verified as a feasible technology for source reduction for contaminated soil with heavy metals. We conducted batch and column leaching experiments to investigate the removal of Cd, Pb, Cu and Zn from smelter soil by citric acid. The removal efficiency of heavy metals by batch leaching reached a maximum (89.1% Cd, 26.8% Pb, 41.7% Zn, 14.2% Cu) at a concentration of 0.1 M and a pH of 5. Citric acid also removed 91.3%, 11.1%, 39.2% and 11.1% of Cd, Pb, Zn, and Cu respectively after column leaching. Citric acid mainly removed exchangeable, carbonate bound and oxide bound Cd, Pb, Cu and Zn fractions. Vertical distributions of Cd, Cu and Zn similarly increased with increasing soil depth. Chestnut shells were applied to the recovery of citric acid from the waste eluent, which removed 84.4%, 97.5%, 74.6%, 70.3% of Cd, Pb, Zn, and Cu, respectively, due to chestnut shell chelation. Fresh and regenerated citric acid was used in batch leaching of heavy metal-contaminated soil, and they showed similar ability to extract heavy metals.

Growing food in polluted soils: A review of risks and opportunities associated with combined phytoremediation and food production (CPFP)

Innumerable private households and small-scale producers currently operate on polluted soils. Phytoremediation is one of the most cost-effective remediation options but as a stand-alone technology, it is often not lucrative enough to make it appealing for farmers, especially in economically vulnerable regions. Economic incentives are crucial for remediation projects to materialise and synergies can be obtained by integrating phytoremediation with other profitable activities including food production. This review aims to synthesise state-of-the-art scientific data to provide a general understanding of opportunities and risks for sustainable remediation of agricultural soil by the use of combined phytoremediation and food production (CPFP). The results show that strategies based on CPFP may be appropriate options for most pollutants in virtually all climatic or socioeconomic contexts but a number of challenges need to be surpassed. The challenges include remediation-technological issues such as undeveloped post-harvest technology and inadequate soil governance. The need for remediation solutions for polluted fields is increasingly urgent since many farmers currently operate on polluted land and the scarcity of soil resources as the human population continuously increases will inevitably force more farmers to cultivate in contaminated areas. We conclude that, although large scale CPFP has not yet reached technological maturity, appropriate combinations of soil types, plant species/cultivars, and agronomic practices together with thorough monitoring of the pollutants' pathways can potentially allow for safe food production on polluted soil that restricts the transfer of a number of pollutants to the food chain while the soil pool of pollutants is gradually reduced.

M. B. Morais A, Freitas AC, C. F. R. Ferreira I, Pintado M. Valorization of Mushroom By-Products as a Source of Value-Added Compounds and Potential Applications

Nowadays, the food sector is highly concerned with environmental issues and foreseen to develop strategies to reduce waste and losses resulting from activities developed in the food system. An approach is to increment added value to the agro-industrial wastes, which might provide economic growth and environmental protection, contributing to a circular economy. Mushroom by-products represent a disposal problem, but they are also promising sources of important compounds, which may be used due to their functional and nutritional properties. Research has been developed in different fields to obtain value added solutions for the by-products generated during mushroom production and processing. Bioactive compounds have been obtained and applied in the development of nutraceutical and pharmaceutical formulations. Additionally, other applications have been explored and include animal feed, fertilizer, bioremediation, energy production, bio-based materials, cosmetics and cosmeceuticals. The main purpose of this review is to highlight the relevant composition of mushroom by-products and discuss their potential as a source of functional compounds and other applications. Future research needs to explore pilot and industrial scale extraction methods to understand the technological feasibility and the economic sustainability of the bioactive compounds extraction and valorization towards different applications.

Removal of polycyclic aromatic hydrocarbons during anaerobic biostimulation of marine sediments

This study proposes the supplementation of digestate, fresh organic fraction of municipal solid waste (OFMSW) and a nutrient solution during the anaerobic biostimulation of marine sediments contaminated by polycyclic aromatic hydrocarbons (PAHs). The experimental activity was conducted with four PAHs (i.e. phenanthrene, anthracene, fluoranthene and pyrene) under controlled mesophilic conditions (37 ± 1 °C) in 100 mL serum bottles maintained at 130 rpm. After 120 days of incubation, the highest total PAH degradation of 53 and 55% was observed in the experiments with digestate + nutrients and OFMSW + nutrients, respectively. Phenanthrene was the most degraded PAH and the highest removal of 69% was achieved with OFMSW + nutrients. The anaerobic PAH degradation proceeded through the accumulation of volatile fatty acids and the production of hydrogen and methane as biogas constituents. The highest cumulative biohydrogen production of 80 mL H₂·g VS^-1 was obtained when OFMSW was used as the sole amendment, whereas the highest biomethane yield of 140 mL CH₄·g VS^-1 was obtained with OFMSW + nutrients. The evolution of PAH removal during anaerobic digestion revealed a higher impact of the methanogenic phase rather than acidogenic phase on PAH degradation.

Degradation of Aflatoxin B1 by a Sustainable Enzymatic Extract from Spent Mushroom Substrate of Pleurotus eryngii

Ligninolytic enzymes from white-rot fungi, such as laccase (Lac) and Mn-peroxidase (MnP), are able to degrade aflatoxin B₁ (AFB1), the most harmful among the known mycotoxins. The high cost of purification of these enzymes has limited their implementation into practical technologies. Every year, tons of spent mushroom substrate (SMS) are produced as a by-product of edible mushroom cultivation, such as Pleurotus spp., and disposed at a cost for farmers. SMS may still bea source of ligninolytic enzymes useful for AFB1 degradation. The in vitro AFB1-degradative activity of an SMS crude extract (SMSE) was investigated. Results show that: (1) in SMSE, high Lac activity (4 U g⁻¹ dry matter) and low MnP activity (0.4 U g⁻¹ dry matter) were present; (2) after 1 d of incubation at 25 °C, the SMSE was able to degrade more than 50% of AFB1, whereas after 3 and 7 d of incubation, the percentage of degradation reached the values of 75% and 90%, respectively; (3) with increasing pH values, the degradation percentage increased, reaching 90% after 3 d at pH 8. Based on these results, SMS proved to be a suitable source of AFB1 degrading enzymes and the use of SMSE to detoxify AFB1 contaminated commodities appears conceivable.

Biodegradation of aged polycyclic aromatic hydrocarbons in agricultural soil by Paracoccus sp. LXC combined with humic acid and spent mushroom substrate

Paracoccus sp. LXC combined with humic acid (HA) and spent mushroom substrate (SMS) obtained from Auricularia auricular and Sarcomyxa edulis was tested for the remediation of agricultural soil contaminated with aged polycyclic aromatic hydrocarbons (PAHs). The biomass and diversity of bacteria and fungi and the soil enzyme activity were analyzed. PAH removal and dissipation kinetics were examined. The highest degradation rate of PAHs was 56.5% when soil was amended with Paracoccus sp. LXC combined with HA and unsterilized SMS from A. auricular. The half-life of PAHs decreased from 2323.3 days in natural attenuation to 66.6-277.2 days in amended treatments. Soil treated with Paracoccus sp. LXC combined with HA and SMS from A. auricular acquired high contents of organic matter and nutrients. HA and SMS aided the growth of PAH-degrading bacteria and promoted the diversity of bacteria but not of fungi. The degradation rate of PAHs was mainly correlated positively with soil laccase activity. Low- and middle-molecular-weight PAHs were significantly removed by Paracoccus sp. LXC, HA and SMS. High-molecular-weight PAHs were removed by SMS but not by Paracoccus sp. LXC. Biodegradation by Paracoccus sp. LXC combined with HA and SMS is a promising choice for remediating aged PAH-contaminated agricultural soils.

First report of the nematicidal activity of Flammulina velutipes, its spent mushroom compost and metabolites

The aim of the present work was to evaluate the nematicidal potential of Flammulina velutipes and its spent mushroom compost. Additionally, the nematicidal activity of enzymes and metabolites was analyzed. Isolated F. velutipes and its SMC had significant nematicidal effect on Panagrellus sp. larvae. The percentages of reduction in relation to the control group were: 69, 57.5 and 70% for SMC and 56, 24.5 and 26.6% for the isolated fungus, for 24, 48 and 72 h, respectively. The active SMC crude extract showed nematicidal action with reduction percentages of 43 and 57% for 24 and 48 h of incubation, respectively. The boiled crude extract also showed nematicidal action, however, the reduction percentages were lower than those of the active extract. This demonstrated that the nematicidal action was due to enzyme activities and other metabolites. The results demonstrated that SMC, the isolated fungus, the crude extract and the boiled crude extract showed a significant percentage of reduction on Panagrellus sp. larvae. SMC evidenced a higher nematicidal activity than the isolated fungus. In addition, nematophagous activity of F. velutipes was observed for the first time.

Mycoremediation of PCBs by Pleurotus ostreatus: Possibilities and Prospects

With the rising awareness on environmental issues and the increasing risks through industrial development, clean up remediation measures have become the need of the hour. Bioremediation has become increasingly popular owing to its environmentally friendly approaches and cost effectiveness. Polychlorinated biphenyls (PCBs) are an alarming threat to human welfare as well as the environment. They top the list of hazardous xenobiotics. The multiple effects these compounds render to the niche is not unassessed. Bioremediation does appear promising, with myco remediation having a clear edge over bacterial remediation. In the following review, the inputs of white-rot fungi in PCB remediation are examined and the lacunae in the practical application of this versatile technology highlighted. The unique abilities of Pleurotus ostreatus and its deliverables with respect to removal of PCBs are presented. The need for improvising P. ostreatus-mediated remediation is emphasized.

Combustion behaviors of pileus and stipe parts of Lentinus edodes using thermogravimetric-mass spectrometry and Fourier transform infrared spectroscopy analyses: Thermal conversion, kinetic, thermodynamic, gas emission and optimization analyses

The combustion behaviors of both Lentinula edodes pileus (LEP) and stipe (LES) were characterized in response to four heating rates in the air atmosphere using thermogravimetric (TG)-mass spectrometry and TG-Fourier transform infrared spectroscopy analyses. There were two and three main peaks of the derivative TG curves for LEP and LES, respectively, with their main combustion stage occurring between 130 and 620 °C. Four iso-conversional models were compared to estimate activation energy values of their combustions. The main emission peaks of most gases ranged from 200 to 350 °C and from 500 to 600 °C for LEP and LES. Their comprehensive combustion parameters at 20 K/min (1.53 and 2.40 × 10^-6 %²/(min²·K³) for LEP and LES, respectively) as well as joint optimizations confirmed their great potential for bioenergy generation. The waste stream of LEP and LES could be well disposed through their combustions with a low level of air pollution.

Bioremediation of Waste Water to Remove Heavy Metals Using the Spent Mushroom Substrate of Agaricus bisporus

The presence of heavy metals in waste water brings serious environmental pollution that threatens human health and the ecosystem. Bioremediation of heavy metals has received considerable and growing interest over the years. Thus, this paper presents the use of the Spent Mushroom Substrate (SMS) of Agaricus bisporus cultivation as a bioremediating agent to remove heavy metals that are present in industrial waters. These metals include chromium, lead, iron, cobalt, nickel, manganese, zinc, copper and aluminium. In particular, this study analyses the performance of SMS bioreactors with different groups of heavy metals at various concentrations. Between 80% and 98% of all contaminants that were analysed can be removed with 5 kg of SMS at hydraulic retention times of 10 and 100 days. The best removal efficiencies and longevities were achieved when removing iron (III), nickel and cobalt from contaminated water at a pH of 2.5. These results suggest that SMS can successfully treat waste water that has been contaminated with heavy metals.

Proteolytic and nematicidal potential of the compost colonized by Hypsizygus marmoreus

Spent mushroom compost (SMC) is a residue generated in edible mushrooms production, such as Hypsizygus marmoreus. Its genome was recently sequenced, demonstrating cuticle-degrading protease genes. The present work aims to investigate the proteases from H. marmoreus spent mushroom compost (SMC) by verifying its action on nematode larvae. The extraction of the crude extract directly with water from H. marmoreus SMC proved to be efficient for proteases obtainment, with proteolytic activity of 195.36 ± 18.38 U g^-1 of compound. Moreover, the zymogram and SDS-PAGE indicated the presence of two proteases with estimated molecular weights of 30.2 and 33.7 kDa. Due to the protease activity present in H. marmoreus SMC extract, there was a significant reduction in the number of Panagrellus redivivus and L₃ in treated group compared to control group (p < 0.01), with 52% and 26% of reduction, respectively. A0A151VWY3 mature protein is composed of 296 amino acid residues, exhibiting molecular weight and pI of 29.5 kDa and 6.72. A0A151WD28 mature protein is composed of 343 amino acid residues, exhibiting molecular weight and pI of 34.4 kDa and 8.04. In the present work it was demonstrated that SMC from H. marmoreus has easily extracted protease content, presenting two proteases, possibly with cuticle-degrading activity, which had significant nematicidal effect on P. redivivus and bovine infective larvae.

Removal of emerging contaminants using spent mushroom compost

Acetaminophen and sulfonamides are emerging contaminants. Conventional wastewater treatment systems fail to degrade these compounds properly. Mycoremediation, is a form of novel bioremediation that uses extracellular enzymes of white-rot fungi to degrade pollutants in the environment. In this study, spent mushroom compost (SMC), which contains fungal extracellular enzymes, was tested for acetaminophen and sulfonamides removal. Among the SMCs of nine mushrooms tested in batch experiments, the SMC of Pleurotus eryngii exhibited the highest removal rate for acetaminophen and sulfonamides. Several fungal extracellular enzymes that might be involved in removal of acetaminophen and sulfonamides were identified by metaproteomic analysis. The bacterial classes, Betaproteobacteria and Alphaproteobacteria, were revealed by metagenomic analysis and may be assisting with acetaminophen and sulfonamide removal, respectively, in the SMC of Pleurotus eryngii. Bioreactor experiments were used to simulate the capability of Pleurotus eryngii SMC for the removal of acetaminophen and sulfonamides from wastewater. The results of this study provide a feasible solution for acetaminophen and sulfonamide removal from wastewater using the SMC of Pleurotus eryngii.

The Evaluation of Hazards to Man and the Environment during the Composting of Sewage Sludge

Composting is considered an effective treatment option to eliminate or substantially reduce potential hazards relating to the recycling of sewage sludge (SS) on land. The variation of four major types of hazards (heavy metals, instability, pathogenic potential and antibiotic resistance) was studied during laboratory-scale composting of two mixtures of sludge and green waste (1:1 and 1:2 v/v). The heavy metal content of the final compost was governed by the initial contamination of SS, with the bulking agent ratio having practically no effect. The composts would meet the heavy metal standards of the United States of America (USA) and the European Union member states, but would fail the most stringent of them. A higher ratio of bulking agent led to a higher stabilisation rate, nitrogen retention and final degree of stability. A good level of sanitisation was achieved for both mixtures, despite the relatively low temperatures attained in the laboratory system. The antibiotic resistance was limited among the E. coli strains examined, but its occurrence was more frequent among the Enterococcus spp. strains. The type of antibiotics against which resistance was mainly detected indicates that this might not be acquired, thus, not posing a serious epidemiological risk through the land application of the SS derived composts.

Earthworm Grazed-Trichoderma harzianum Biofortified Spent Mushroom Substrates Modulate Accumulation of Natural Antioxidants and Bio-Fortification of Mineral Nutrients in Tomato

The present investigation was aimed at evaluating the impact of earthworm grazed and Trichoderma harzianum biofortified spent mushroom substrate (SMS) on natural antioxidant and nutritional properties of tomato. Results of the investigation reveal that earthworm grazing and T. harzianum bio-fortification led to significant improvement in the physico-chemical properties of fresh SMS and its application increased the accumulation of natural antioxidants and mineral content in tomato as compared to either T. harzianum biofortified SMS or fresh SMS. In particular, the earthworm grazed, T. harzianum biofortified SMS (EGTHB-SMS) was found to inhibit lipid peroxidation and protein oxidation with significant increase in total polyphenol and flavonoid content in tomato. Further, it increased Fe2+/Fe3+ chelating activity, superoxide anion radical scavenging activity compared to other treatments. The results thus suggest an augmented elicitation of natural antioxidant properties in tomato treated with EGTHB-SMS, resulting in a higher radical scavenging activity, that is highly desirable for human health. In addition, the use of SMS to enhance the nutritional value of tomato fruits becomes an environment friendly approach in sustainable crop production.