A novel strategy for producing cellulase from Trichoderma reesei with ultrasound‐assisted fermentation using spent mushroom substrate

Emerging technologies for the extraction of bioactives from mushroom waste

Extraction of bioactive compounds for application in nutraceuticals is gaining popularity. For this, there is a search for low-cost substrates that would make the end product and the process more economical. Mushroom waste (stalk, cap, stem etc.) is one such high valued substrate that has received much attention recently due to its rich reserves of terpenoids, polyphenols, sesquiterpenes, alkaloids, lactones, sterols, antioxidative vitamins, anthocyanidins, glycoproteins and polysaccharides, among others. However, there is a need to identify green and hybrid technologies that could make the bioactive extraction process from these substrates safe, efficient and sustainable. To this effect, many emerging technologies (supercritical fluid, ultrasound-, enzyme- and microwave-assisted extraction) have been explored in the last decade which have shown potential for scale-up with high productivity. This review systematically discusses such technologies highlighting the current challenges faced during waste processing and the research directives needed for further advancements in the field.

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.

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.

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

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

Biomolecules in modern and sustainable agriculture

This review presents scientific findings which indicate biomolecules are excellent candidates for the development of biopesticides. Efforts are being done to find routes to increase their concentrations in the cultivation media because this concentration facilitates applications, storage, and transportation. Some of these routes are co-fermentation and ultrasound-assisted fermentation. Ultrasonication increases metabolite production and growth rates by improvement of cell permeability and nutrient uptake rates through cell membranes. For example, 24% increase in the enzymatic activity of cellulases produced by Trichoderma reesei in solid-state fermentation was achieved with ultrasonication. Also, chitinase and β-1,3-glucanase productions were stimulated by ultrasound in Beauveria bassiana cultivation, presenting positive results. The common parameters evaluated in the production of biomolecules by ultrasound-assisted fermentation are the duty cycle, time of application, power, energetic density, and how long the sonication is maintained in the fermentation media. Many successful cases are reported and discussed, which include the final formulation of bioproducts for agricultural applications. In this trend, nanotechnology is a promising tool for the development of nanoformulations. Nanoemulsification, green synthesis, biosynthesis, or biogenic synthesis are technologies used to produce such nanoformulations, allowing the controlled release of control agents, as well as the delivery of biomolecules to specific targets.

Valorization of mushroom by-products: a review

With the rapid growth of the global economy and the global population, the production of solid waste has increased remarkably. Mushrooms are gaining popularity among researchers for their ability to turn waste into nutrients. However, a large number of by-products are produced during the industrial processing of mushrooms. Traditional waste management, focusing on the utilization and disposal of mushroom by-products, has attracted the attention of researchers. Meanwhile, the circular economy has become a multidisciplinary research field, and the valorization of mushroom by-products is a very important part of circular economy research. Various mushroom by-products of mushroom are reviewed in this paper. By-products are used in food as raw materials or functional components, in livestock and poultry feed after grinding/fermentation, and as electrochemical materials and papermaking materials. The by-products can also be used to produce ethanol and other biological sources of energy, as absorbing substances in sewage treatment, and as fertilizer in soil amendment. Mushroom processing by-products can be applied in various fields. To improve production efficiency, new extraction technology (including supercritical fluid technology and microwave extraction technology) can be adopted to increase the bioactive substance content in the by-products. Choosing appropriate processing temperature, time, and other processing conditions can also enhance product quality. Finally, more research is needed on the cost-effective utilization of the by-products and the feasibility of industrialization. © 2022 Society of Chemical Industry.

Optimization of ultrasound-assisted production of ergosterol from Penicillium brevicompactum by Taguchi statistical method

Ergosterol as a primary metabolite and precursor of vitamin D2, is the most plentiful mycosterols in fungal cell membrane. Process optimization to increase the yield and productivity of biological products is a topic of interest. Ultrasonic waves have many applications in biotechnology, like cell disruption, and enhancement of primary and secondary metabolites production. This study disclosed an optimal condition for ultrasound-assisted production (UAP) of ergosterol from Penicillium brevicompactum MUCL 19,011 using L₉ Taguchi statistical method. The intensity (IS), time of sonication (TS), treatment frequency (TF), and number of days of treatment (DT) were allocated to study the effects of ultrasound on ergosterol production. The results were analyzed using Minitab version 19. The maximum ergosterol, 11 mg/g cell dry weight (CDW), was produced on the tenth day while all factors were at a low level. The days of treatment with a contribution of 45.48% was the most significant factor for ergosterol production. For the first time, this study revealed the positive effect of ultrasound on the production of ergosterol. Ergosterol production increased 73% (4.63 mg/g CDW) after process optimization. Finally, a mathematical model of ultrasound factors with a regression coefficient of R² = 0.978 was obtained for the ergosterol production during ultrasound treatment.