Use of lignocellulosic substrate colonized by oyster mushroom (Pleurotus ostreatus) for removal of organic micropollutants from water

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.

Use of sawdust for production of ligninolytic enzymes by white-rot fungi and pharmaceutical removal

Use of white-rot fungi for enzyme-based bioremediation of wastewater is of high interest. These fungi produce considerable amounts of extracellular ligninolytic enzymes during solid-state fermentation on lignocellulosic materials such as straw and sawdust. We used pure sawdust colonized by Pleurotus ostreatus, Trametes versicolor, and Ganoderma lucidum for extraction of ligninolytic enzymes in aqueous suspension. Crude enzyme suspensions of the three fungi, with laccase activity range 12-43 U/L and manganese peroxidase activity range 5-55 U/L, were evaluated for degradation of 11 selected pharmaceuticals spiked at environmentally relevant concentrations. Sulfamethoxazole was removed significantly in all treatments. The crude enzyme suspension from P. ostreatus achieved degradation of wider range of pharmaceuticals when the enzyme activity was increased. Brief homogenization of the colonized sawdust was also observed to be favorable, resulting in significant reductions after a short exposure of 5 min. The highest reduction was observed for sulfamethoxazole which was reduced by 84% compared to an autoclaved control without enzyme activity and for trimethoprim which was reduced by 60%. The compounds metoprolol, lidocaine, and venlafaxine were reduced by approximately 30% compared to the control. Overall, this study confirmed the potential of low-cost lignocellulosic material as a substrate for production of enzymes from white-rot fungi. However, monitoring over time in bioreactors revealed a rapid decrease in enzymatic ligninolytic activity.

Removal and degradation of sodium diclofenac via radical-based mechanisms using S. sclerotiorum laccase

The recently isolated Sclerotinia sclerotiorum laccase was used for the degradation of sodium diclofenac, a nonsteroidal anti-inflammatory drug widely found in the aquatic environment. The Michaelis-Menten parameters, half-life of diclofenac at different pH values in presence of this enzyme and potential inhibitors were evaluated. Diclofenac-based radicals formed in presence of laccase were spin-trapped and detected using EPR spectroscopy. Almost complete diclofenac degradation (> 96%) occurred after a 30-h treatment via radical-based generated oligomers and their rapid precipitation, thus ensuring an unprecedented green formula suitable not only for degradation but also for straightforward removal of the degradation products. High performance liquid chromatography coupled with atmospheric pressure chemical ionization-ion trap mass spectrometry (HPLC-APCI-MS) analyses of the degradation products of diclofenac in aqueous dosage revealed the presence of at least seven products while HR Orbitrap MS analysis showed that the enzymatic treatment produced high molecular weight metabolites through a radical oligomerization mechanism of diclofenac. The enzymatically formed products precipitated and its constituting components were also characterized using UV-vis spectroscopy, infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA).

Mechanism of fungal remediation of wetland water: Stropharia rugosoannulata as promising fungal species for the development of biofilters to remove clinically important pathogenic and antibiotic resistant bacteria in contaminated water

Mycoremediation uses mushroom forming fungi for remediation of sites contaminated with biotic and abiotic contaminants. The root-like hyphae of many fungi, the mycelia, have been used to remediate soil and water. In this study mushroom mycelia biofilters were evaluated for remediation efficacy of wetland water polluted with crow feces containing antibiotic resistant (AMR) bacteria. Three strains of fungi, Pleurotus ostreatus, Stropharia rugosoannulata, and Pleurotus pulmonarius, were allowed to develop dense mycelia for 3-5 weeks on wood chips within cylindrical jars. Biofilter jars were incubated with wetland water (WW) obtained from a crow roost area that was additionally spiked with AMR bacteria isolated from previous crow fecal collections. E. coli, Staphylococcus aureus, Enterococcus faecium, Campylobacter jejuni, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Salmonella enteritidis were added at concentrations of 1,500-3,500 CFU/100 ml. Remediation was calculated from bacterial counts or gene copy numbers (GCN), before and after passage of water through jars. Stropharia and P. pulmonarius biofilters remediated all bacteria, but Klebsiella, in the range of 43-78%, after 1 h. Incubation of water for 24 h showed Stropharia remediation to be superior relative to other tested fungi. Percent remediation varied as follows: S. aureus-100%, E. faecium-97%, C. jejuni-59%, P. aeruginosa-54%, E. coli-65% and S. enteritidis-27%. The mechanism of remediation was tested by removing the mycelium from the biofilter column after passage of water, followed by extraction of DNA. Association of bacterial DNA with the mycelia was demonstrated by qPCR for all bacteria, except S. aureus and Salmonella. Depending on the bacteria, the GCN ranged from 3,500 to 54,000/250 mg of mycelia. Thus, some of the ways in which mycelia biofilters decrease bacteria from water are through bio-filtration and bio-absorption. Active fungal growth and close contact with bacteria appear necessary for removal. Overall these results suggest that mushroom mycelia biofilters have the potential to effectively remediate water contaminated with pathogenic and AMR bacteria.

Biotechnological Applications of Mushrooms under the Water-Energy-Food Nexus: Crucial Aspects and Prospects from Farm to Pharmacy

Mushrooms have always been an important source of food, with high nutritional value and medicinal attributes. With the use of biotechnological applications, mushrooms have gained further attention as a source of healthy food and bioenergy. This review presents different biotechnological applications and explores how these can support global food, energy, and water security. It highlights mushroom's relevance to meet the sustainable development goals of the UN. This review also discusses mushroom farming and its requirements. The biotechnology review includes sections on how to use mushrooms in producing nanoparticles, bioenergy, and bioactive compounds, as well as how to use mushrooms in bioremediation. The different applications are discussed under the water, energy, and food (WEF) nexus. As far as we know, this is the first report on mushroom biotechnology and its relationships to the WEF nexus. Finally, the review valorizes mushroom biotechnology and suggests different possibilities for mushroom farming integration.

A review of hybrid enzymatic-chemical treatment for wastewater containing antiepileptic drugs

Epilepsy is one of the most common neurological diseases worldwide and requires treatment with antiepileptic drugs for many years or for life. This fact leads to the need for constant production and use of these compounds, placing them among the four pharmaceutical classes most found in wastewater. Even at low concentrations, antiepileptics pose risks to human and environmental health and are considered organic contaminants of emerging concern. Conventional treatments have shown low removal of these drugs, requiring advanced and innovative approaches. In this context, this review covers the results and perspectives on (1) consumption and occurrence of antiepileptics in water, (2) toxicological effects in aquatic ecosystems, (3) enzymatic and advanced oxidation processes for degrading antiepileptics drugs from a molecular point of view (biochemical and chemical phenomena), (4) improvements in treatment efficiency by hybridization, and (5) technical aspects of the enzymatic-AOP reactors.

Textile azo dyes discolouration using spent mushroom substrate: enzymatic degradation and adsorption mechanisms

This study evaluated the adsorption and enzymatic degradation of azo dyes when using SMS. The laccase present in the SMS was characterised, and the maximum activity was obtained at pH 2, a temperature of 45°C, a Michaelis-Menten constant (Km) of 0.264 mM, and a maximum reaction rate (Vmax) of 117.95 µmol L-1 min-1. The presence of NaCl at 5 mM inhibited enzyme activity while no inhibition was observed by Na2SO4, typically found in textile wastewater. The maximum dye adsorption (57.22%) was achieved at pH 8.0, 25°C, and 100 g L-1 of SMS while the maximum enzymatic degradation (14.18%) was obtained under the same conditions, except at pH 4.0. The enzymes laccase, lignin peroxidase, and manganese peroxidase trapped in the SMS resulted in higher dye discolouration when compared to that extracted with aqueous solution, meaning that SMS has strong adsorption capacity and is a natural immobilisation matrix, which improves the enzymatic degradation of the dyes. Thus, SMS can be used in the treatment of textile effluents for dye removal by simultaneous mechanisms of adsorption and enzymatic degradation, with reduction of environmental impacts for SMS disposal and reduction of the costs associated with commercial enzymes and adsorbents.

Current Challenges for Biological Treatment of Pharmaceutical-Based Contaminants with Oxidoreductase Enzymes: Immobilization Processes, Real Aqueous Matrices and Hybrid Techniques

The worldwide access to pharmaceuticals and their continuous release into the environment have raised a serious global concern. Pharmaceuticals remain active even at low concentrations, therefore their occurrence in waterbodies may lead to successive deterioration of water quality with adverse impacts on the ecosystem and human health. To address this challenge, there is currently an evolving trend toward the search for effective methods to ensure efficient purification of both drinking water and wastewater. Biocatalytic transformation of pharmaceuticals using oxidoreductase enzymes, such as peroxidase and laccase, is a promising environmentally friendly solution for water treatment, where fungal species have been used as preferred producers due to their ligninolytic enzymatic systems. Enzyme-catalyzed degradation can transform micropollutants into more bioavailable or even innocuous products. Enzyme immobilization on a carrier generally increases its stability and catalytic performance, allowing its reuse, being a promising approach to ensure applicability to an industrial scale process. Moreover, coupling biocatalytic processes to other treatment technologies have been revealed to be an effective approach to achieve the complete removal of pharmaceuticals. This review updates the state-of-the-art of the application of oxidoreductases enzymes, namely laccase, to degrade pharmaceuticals from spiked water and real wastewater. Moreover, the advances concerning the techniques used for enzyme immobilization, the operation in bioreactors, the use of redox mediators, the application of hybrid techniques, as well as the discussion of transformation mechanisms and ending toxicity, are addressed.

Role of ascomycete and basidiomycete fungi in meeting established and emerging sustainability opportunities: a review

Fungal biomass is the future's feedstock. Non-septate Ascomycetes and septate Basidiomycetes, famously known as mushrooms, are sources of fungal biomass. Fungal biomass, which on averagely comprises about 34% protein and 45% carbohydrate, can be cultivated in bioreactors to produce affordable, safe, nontoxic, and consistent biomass quality. Fungal-based technologies are seen as attractive, safer alternatives, either substituting or complementing the existing standard technology. Water and wastewater treatment, food and feed, green technology, innovative designs in buildings, enzyme technology, potential health benefits, and wealth production are the key sectors that successfully reported high-efficiency performances of fungal applications. This paper reviews the latest technical know-how, methods, and performance of fungal adaptation in those sectors. Excellent performance was reported indicating high potential for fungi utilization, particularly in the sectors, yet to be utilized and improved on the existing fungal-based applications. The expansion of fungal biomass in the industrial-scale application for the sustainability of earth and human well-being is in line with the United Nations' Sustainable Development Goals.

Green Biotechnology of Oyster Mushroom (Pleurotus ostreatus L.): A Sustainable Strategy for Myco-Remediation and Bio-Fermentation

The field of biotechnology presents us with a great chance to use many organisms, such as mushrooms, to find suitable solutions for issues that include the accumulation of agro-wastes in the environment. The green biotechnology of mushrooms (Pleurotus ostreatus L.) includes the myco-remediation of polluted soil and water as well as bio-fermentation. The circular economy approach could be effectively achieved by using oyster mushrooms (Pleurotus ostreatus L.), of which the substrate of their cultivation is considered as a vital source for producing biofertilizers, animal feeds, bioenergy, and bio-remediators. Spent mushroom substrate is also considered a crucial source for many applications, including the production of enzymes (e.g., manganese peroxidase, laccase, and lignin peroxidase) and bioethanol. The sustainable management of agro-industrial wastes (e.g., plant-based foods, animal-based foods, and non-food industries) could reduce, reuse and recycle using oyster mushrooms. This review aims to focus on the biotechnological applications of the oyster mushroom (P. ostreatus L.) concerning the field of the myco-remediation of pollutants and the bio-fermentation of agro-industrial wastes as a sustainable approach to environmental protection. This study can open new windows onto the green synthesis of metal-nanoparticles, such as nano-silver, nano-TiO2 and nano-ZnO. More investigations are needed concerning the new biotechnological approaches.

Fluoxetine Removal from Aqueous Solutions Using a Lignocellulosic Substrate Colonized by the White-Rot Fungus Pleurotus ostreatus

One of the main challenges in both the design of new wastewater treatment plants and the expansion and improvement of existing ones is the removal of emerging pollutants. Therefore, the search for economic and sustainable treatments is needed to enhance the removal of pharmaceuticals. The potential of a lignocellulosic substrate colonized by Pleurotus ostreatus, a waste from mushroom production, to remove fluoxetine from aqueous solutions was studied. Batch assays were performed to remove 600 µg∙L⁻¹ fluoxetine from aqueous solutions using the colonized mushroom substrate (CMS) and crude enzyme extracts. The removal efficiencies achieved were, respectively, ≥83.1% and 19.6% in 10 min. Batch assays with sterilized CMS and 1-aminobenzotriazole (to inhibit cytochrome P450 enzymes) showed that the higher removal efficiencies achieved in the CMS assays may be attributed to the synergistic contribution of biosorption onto the CMS and lignin modifying enzymes activity, namely laccase activity. A column assay was performed with the CMS, fed with 750 µg∙L⁻¹ fluoxetine aqueous solution. The removal efficiency was 100% during 30 min, decreasing to a final value of 70% after 8 h of operation. The results suggested that CMS can be a promising eco-friendly alternative to remove fluoxetine from aqueous solutions.

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.

Use of sugar mill wastewater for Agaricus bisporus cultivation: prediction models for trace metal uptake and health risk assessment

This study explored the sustainable use of treated sugar mill wastewater (SMW) to cultivate the White button (Agaricus bisporus J.E. Lange) mushroom and the attendant risk of trace metals accumulated in the fruiting bodies. The wheat straw substrate was loaded with a normal water supply and different doses of SMW to enhance its moisture and nutrient contents. The impact of the SMW amendment on A. bisporus yield, biological efficiency, and spawn-running time was assessed. Furthermore, the substrate properties (pH, organic matter, total nitrogen, total phosphorus, etc.) based prediction models for trace metal uptake by A. bisporus fruiting bodies were developed using multiple linear regression (MLR) and artificial neural network (ANN) approaches. The results showed that maximum A. bisporus yield (158.42 ± 8.74 g/kg fresh substrate), biological efficiency (105.61 ± 3.97%), and minimum time of spawn-running (15 days) were observed in 75% SMW enrichment. For the prediction of Cd, Cu, Cr, Fe, Mn, and Zn trace metal uptake, the ANN models showed better performance in terms of R² (> 0.995), root means square error (RMSE < 0.075), model efficiency (ME > 0.99), and model normalized bias (MNB < 0.009), as compared with those of MLR models with R² (0.972), RMSE (< 0.441), ME (> 0.96), and MNB (< 0.034), respectively. On the other hand, the target hazard quotient (THQ) showed no significant health risk associated with the consumption of trace metal-contaminated A. bisporus in both adult and child groups. Thus, the findings of this study present a novel, safe, and sustainable method of A. bisporus cultivation along with treated agro-based wastewater management.

Biological efficiency and nutritional value of Pleurotus ostreatus cultivated in agroindustrial wastes of palm oil fruits and cocoa almonds

ABSTRACT The cocoa and palm oil agro-industries active in the state of Bahia, Brazil, generate high quantities of lignocellulosic wastes that could be recycled through their use in the formulation of substrates to cultivate edible mushrooms. Pleurotus ostreatus, also known as oyster mushroom, is the second most cultivated mushroom in the world due to its highly appreciated gastronomic, nutritional, and medicinal characteristics. This work evaluated the vertical mycelium growth, biological efficiency, mushroom yield, and nutritional composition of P. ostreatus produced in substrates formulated with a combination of palm oil fruit mesocarp (POFM) and cocoa almond peels (CAP) processing wastes. The substrates were formulated with the following POFM/CAP proportions (%/%): S1 – 86.4/9.6; S2 – 76.8/19.2; S3 – 67.2/28.8; S4 – 57.6/38.4, and S5 – 48.0/48.0. Substrates also received 3% powdered charcoal and 1% calcium carbonate. Substrates S1, S2, S3, and S4 were superior for vertical mycelium growth. S2 promoted the best biological efficiency (148.8%) and yield (560.5g·kg-1).The mushrooms produced in all substrates presented good nutritional values, although mushrooms produced using the S2 presented the highest crude protein content. Overall, S1 is the recommended substrate as it results in higher yields of nutrient rich mushrooms. Production of P. ostreatus in substrates composed of POFM and CAP represents a good alternative for recycling these wastes with potential economic and ecological benefits to regions where palm oil and cocoa are grown.