Accumulation of Selected Metal Elements in Fruiting Bodies of Oyster Mushroom

Evaluation of Two Different Treatments for Larch Logs as Substrates to Cultivate Ganoderma tsugae in the Forest

Larch wood, a prevalent cultivation medium for Ganoderma tsugae, has yet to be scrutinized concerning the differential impacts of sterilized and non-sterilized substrates on the growth and development of this fungus. Our present investigation sought to elucidate these effects in a forest-like environment. After larch wood segments were sun-dried, they were divided into two groups; one group was bagged and autoclaved, while the other group was bagged without any treatment. Subsequently, all segments were inoculated with the G. tsugae strain HLXL1 and ensconced under the canopy of a Pinus koraiensis forest, thereby approximating the conditions of natural growth. Wild G. tsugae was used as the control. Data on agronomic traits, production days, fruiting body yield, and effective constituent content were analyzed. The results indicated no significant differences between sterilized and non-sterilized substrates in terms of agronomic traits. However, the mineral content and bioactive compounds in G. tsugae fruiting bodies significantly differed across various growth stages. The outcomes were optimal for non-sterilized substrates, followed by sterilized substrates, while the wild strains were markedly less effective than the cultivated ones.

Quantification of Minerals in Edible Mushrooms via Optimized Microwave-Assisted Digestion: Nutritional Contributions of Fe, Mg, Na, K, and Ca

The intake of mushrooms provides numerous beneficial properties for the correct functioning of the human body due to their rich content in carbohydrates, proteins, fibers, vitamins, and minerals. However, most of the reports are focused on the determination of bioactive compounds and only a few regarding the essential mineral content and the evaluation of the RDI. Thus, the aim of this study was to determine the mineral composition of different cultivated (A. bisporus and P. ostreatus) and wild edible mushrooms (A. crocodilinus, A. arvensis, A. silvicola, A. impudicus, M. mastoidea, M. rhacodes, and P. ostreatus) collected in the south of Spain and north of Morocco. First, the optimization of a microwave-assisted digestion method was carried out using a Box-Behnken design with a response surface methodology to quantify the total content of five metals: Fe, Mg, Na, K, and Ca in mushrooms. The samples were analyzed by FAAS and ICP-OES. The percentage of the RDI of each mineral covered by the intake of mushrooms was calculated. It was observed that a high percentage of RDI levels are covered and just exceeded for Fe. Thence, due to their beneficial properties and high content of essential minerals, mushrooms would be proposed as a valuable source of nutrients to manufacture some food supplements.

Food and human health applications of edible mushroom by-products

Mushroom waste can account for up to 50% of the total mushroom mass. Spent mushroom substrate, misshapen mushrooms, and mushroom stems are examples of mushroom byproducts. In ancient cultures, fungi were prized for their medicinal properties. Aqueous extracts containing high levels of β-glucans as functional components capable of providing prebiotic polysaccharides and improved texture to foods have been widely used and new methods have been tested to improve extraction yields. Similarly, the addition of insoluble polysaccharides controls the glycemic index, counteracting the effects of increasingly high-calorie diets. Numerous studies support these benefits in vitro, but evidence in vivo is scarce. Nonetheless, many authors have created a variety of functional foods, ranging from yogurt to noodles. In this review, we focus on the pharmacological properties of edible mushroom by-products, and the possible risks derived from its consumption. By incorporating these by-products into human or animal feed formulations, mushroom producers will be able to fully optimize crop use and pave the way for the industry to move toward a zero-waste paradigm.

Utilization of local agro-industrial by-products based substrates to enhance production and dietary value of mushroom (P. ostreatus) in Ethiopia

Food insecurity and malnutrition are serious problems in many developing countries, including Ethiopia. This situation warrants an urgent need for the diversification of food sources with enhanced productivity. This study was aimed at contributing to the food security in Ethiopia through cultivation of Pleurotus ostreatus mushrooms using sustainable and locally available agro-industrial byproduct-based substrates in parallel with pollution control. Ten substrates were prepared using sugarcane bagasse, filter cake, trash, cotton seed hull and animal waste, namely cow dung and horse and chicken manure. The effect of each substrate (treatment) on the yields, biological efficiency, nutritional composition, and mineral contents of Pleurotus ostreatus mushroom species was evaluated at the Ethiopian Forest Products Innovation Center, Addis Ababa, Ethiopia. The results obtained indicate that a significantly higher (p < 0.05) yield and biological efficiency were recorded from the mushroom cultivated on S2 substrate containing a mixture of 80% sugarcane bagasse, 12% cow dung, and 8% cotton seed hull. Moreover, substrate containing sugarcane bagasse mixed with cotton seed hull, cow dung, and chicken manure significantly (p < 0.05) increased the yields and biological efficiency of the mushroom. The content of protein, crude fat, fiber, and carbohydrates of the mushroom cultivated from all the utilized substrates were in the range of 17.30-21.5, 1.77-2.52, 31.03-34.38, and 28.02-39.74%, respectively. The critical macro-elements are abundant in the mushroom in the order of potassium, magnesium, calcium, and sodium. The mushrooms cultivated on all the substrates were rich in essential micro-elements in the order of iron and zinc. It was found that substrate preparation and formulation significantly (p < 0.05) improved the yields, biological efficiency, nutritive values, and mineral contents of the mushroom. The use of these by-products as substrates is sustainable and environmentally friendly and allows the production of mushroom with high nutritional value on a sustainable basis in order to enhance food security in the country.

Basidiomycetes to the rescue: Mycoremediation of metal-organics co-contaminated soils

The increasing need for metals leads to contaminated post-mining landscapes. At the same time, the contamination with organic, recalcitrant contamination increases. This poses a problem of reuse of large areas, often co-contaminated with both, metals, and organic pollutants. For the remediation of areas contaminated with multiple contaminants and combining many stress factors, technical solutions including groundwater treatment, where necessary, have been devised. However, this is applied to highly contaminated, small sites. The reuse of larger, co-contaminated landscapes remains a major challenge. Mycoremediation with fungi offers a good option for such areas. Fungi cope particularly well with heterogeneous conditions due to their adaptability and their large hyphal network. This chapter summarizes the advantages of basidiomycetes with a focus on wood rot fungi in terms of their ability to tolerate metals, radionuclides, and organic contaminants such as polycyclic aromatic hydrocarbons. It also shows how these fungi can reduce toxicity of contaminants to other organisms including plants to allow for restored land-use. The processes based on diverse molecular mechanisms are introduced and their use for mycoremediation is discussed.

Pre- and Postharvest Strategies for Pleurotus ostreatus Mushroom in a Circular Economy Approach

Mushroom cultivation presents a viable solution for utilizing agro-industrial byproducts as substrates for growth. This process enables the transformation of low-economic-value waste into nutritional foods. Enhancing the yield and quality of preharvest edible mushrooms, along with effectively preserving postharvest mushrooms, stands as a significant challenge in advancing the industry. Implementing pre- and postharvest strategies for Pleurotus ostreatus (Jacq.) P. Kumm (oyster mushroom) within a circular economy framework involves optimizing resource use, minimizing waste, and creating a sustainable and environmentally friendly production system. This review aimed to analyze the development and innovation of the different themes and trends by bibliometric analysis with a critical literature review. Furthermore, this review outlines the cultivation techniques for Pleurotus ostreatus, encompassing preharvest steps such as spawn production, substrate preparation, and the entire mushroom growth process, which includes substrate colonization, fruiting, harvesting, and, finally, the postharvest. While novel methodologies are being explored for maintaining quality and extending shelf-life, the evaluation of the environmental impact of the entire mushroom production to identify areas for improvement is needed. By integrating this knowledge, strategies can be developed for a more sustainable and circular approach to Pleurotus ostreatus mushroom cultivation, promoting environmental stewardship and long-term viability in this industry.

Commercial scale production of Yamabushitake mushroom (Hericium erinaceus (Bull.) Pers. 1797) using rubber and bamboo sawdust substrates in tropical regions

Yamabushitake (Hericium erinaceus) is one of the most sought out mushrooms that is widely used for both direct consumption and medicinal purposes. While its demand increases worldwide, cultivation of the mushroom is limited to temperate areas and its production in tropical regions has never been explored. The aim of this study was to test the utilization of rubber and bamboo sawdust, alone or as a substrate mixture, for industrial scale Yamabushitake mushroom production. Five substrate treatments with various ratios of the two sawdust were compared for their physicochemical properties in relation to mushroom productivity. The highest mushroom fresh and dry (113.22 and 23.25 g, respectively), biological efficiency (42.61%), and cap size (9.53 cm) were obtained from the substrates containing 100% rubber sawdust, with the mushroom yield decreasing proportional to the ratio of bamboo sawdust. The 100% rubber sawdust substrate provided a higher initial organic matter and carbon content together with C:N ratio at 63.2%, 36.7% and 65.48, respectively, whereas the 100% bamboo sawdust provided higher nitrogen content (1.03%), which was associated with lower mushroom yield but higher number of fruiting bodies. As in the 100% rubber sawdust substrate, a comparable mushroom yield and growth attributes were also obtained in the 3:1 rubber-bamboo sawdust mixture substrate. Principle component analysis of the measured variables indicated a strong influence of substrate C:N ratio before spawning and the change in substrate electrical conductivity and N content after cultivation to the variation in mushroom productivity among the treatments. The results demonstrate the applicability of rubber sawdust and its combination with up to 25% of bamboo sawdust for Yamabushitake mushroom cultivation and provide the basis for substrate optimization in the tropical Yamabushitake mushroom industry through a circular economy framework.

Feasibility study for mercury remediation by selenium competition in Pleurotus mushrooms

Mushrooms may incorporate significant levels of Hg making its consumption harmful to human health. Mercury remediation induced by Se competition in edible mushrooms represents a valuable alternative since Se plays effective roles against Hg uptake, accumulation, and toxicity. In this way, Pleurotus ostreatus and Pleurotus djamor were cultivated on Hg-contaminated substrate simultaneously supplemented with Se(IV) or Se(VI) under different dosages in this study. The protective role of Se was assessed taking into account morphological characteristics and Hg and Se total concentrations determined by ICP-MS, as well as proteins and protein-bound Hg and Se distribution by SEC-UV-ICP-MS, and Hg speciation studies (Hg(II) and MeHg) by HPLC-ICP-MS. Both Se(IV) and Se(VI) supplementation were able to recover the morphology mainly of Hg-contaminated Pleurotus ostreatus. The mitigation effects induced by Se(IV) stood out more than Se(VI) in terms of Hg incorporation, decreasing the total Hg concentration up to 96 %. Also, it was found that supplementation mainly with Se(IV) reduced the fraction of Hg bound to medium molecular weight compounds (17-44 kDa) up to 80 %. Finally, it was shown a Se-induced inhibitory effect on Hg methylation, decreasing MeHg species content in mushrooms exposed to Se(IV) (51.2 µg g^-1) up to 100 %.

Production of oyster mushroom (Pleurotus ostreatus) on sawdust supplemented with anaerobic digestate

Anaerobic digestion of organic waste results in production of biogas and a nutrient-rich digestate that has an established use as fertilizer in plant production. This study evaluated use of anaerobic digestate based on a high concentration of organic household waste as a fertilizer in sawdust-based production of oyster mushrooms (Pleurotus ostreatus). Inclusion of 0.5 L of anaerobic digestate (AD) per kg sawdust gave similar productivity in terms of biological efficiency (79.5 ± 5.4 %), and protein concentration (24.7 ± 2.4 % of dry weight (dw)) as standard mushroom substrate (78.1 ± 5.3 %, and 21.9 ± 3.0 % of dw, respectively). However, mushroom growth was impaired at the highest concentration of anaerobic digestate tested, 1 L digestate per kg dw sawdust. Comparison of the AD-fertilized substrate with a mushroom substrate with standard components (sawdust, wheat bran, calcium sulfate) and with similar C/N-ratio revealed some differences in elemental composition of the fruiting bodies, with an major increase in sodium concentration for the AD-fertilized substrate compared with the standard substrate (413.3 ± 28.9 and 226.7 ± 30.6 mg kg^-1 dw, respectively). This difference can be explained by high sodium concentration in the anaerobic digestate, most likely due to inclusion of food scraps from households and restaurants in the biodigester feedstock. Screening of both substrates for a total of 133 micropollutants revealed that total sum of micropollutants was significantly higher in the AD-fertilized substrate (258 ± 12 ng/g dw substrate) than in the standard substrate (191 ± 35 ng/g dw substrate). Nitrogen losses during preparation of the AD-fertilized substrate were negligible.

Analysis of Biochemical and Genetic Variability of Pleurotus ostreatus Based on the β-Glucans and CDDP Markers

Oyster mushroom (Pleurotus ostreatus) is still one of the most cultivated edible and medicinal mushrooms. Despite its frequent cultivation around the world, there is currently just a little information available on the variability of strains in terms of the content of β-glucans in them. This work presents an extensive study of 60 strains in terms of the content of α-glucans and β-glucans in their caps and stipes. The authenticity of the production strains based on an analysis of the variability of their genome by CDDP (Conserved DNA-derived polymorphism) markers was confirmed, whereas identical CDDP profiles were identified between samples 45, 89, 95, and 96. Genetic variability of the analyzed production strains showed a high polymorphism and effective discriminative power of the used marking technique. Medium positive correlations were found among the CDDP profiles and β-glucan content in the group of strains that generated the same CDDP profiles, and low negative correlation was found among these profiles in the group of low β-glucan content strains. For the determination of glucans content, Mushroom and Yeast analytical enzymatic kit (Megazyme, Bray, Co. Wicklow, Ireland) were used. The results clearly showed that the stipe contains on average 33% more β-glucans than the cap. The minimum detected β-glucan content in the stipe was in strain no. 72, specifically 22%, and the maximum in strain no. 43, specifically 56%, which after the conversion represents a difference of 155%. From the point of view of β-glucan content, the stated strain no. 43 appears to be very suitable for the commercial production of β-glucans under certain conditions.

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.