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.

Integrating Taguchi method and artificial neural network for predicting and maximizing biofuel production via torrefaction and pyrolysis.

Artificial neural network (ANN) is one kind of artificial intelligence in the computing system that aims to process information as the way neurons in the human brain. In this study, the combination of the Taguchi method and ANN are used to maximize and predict biofuel yield from spent mushroom substrate torrefaction and pyrolysis via microwave irradiation. The Taguchi method is utilized to design the multiple factors (particle size, catalyst, power, and magnetic agent) and levels of experiment parameters. The highest total biofuel yield (biochar + bio-oil) is 99.42%, accomplished by a combination of 355 µm particle size, 300 mg·g-SMS-1 catalyst, 900 W power, and 300 mg·g-SMS-1 magnetic agent. ANN with one hidden layer shows the outstanding linear regression predictions for the highest biofuel yields (biochar 0.9999 and bio-oil 0.9998). This high linear regression indicates that ANN with a quick propagation algorithm is an appropriate approach for predicting biofuel conversion.

Extraction of polysaccharides from edible mushrooms: Emerging technologies and recent advances.

Mushroom-derived polysaccharides (especially ß-glucans) are gaining much interest from researchers and industries recently due to their antioxidant, antitumor, immune-modulating activities, and other health benefits. Besides conventional extraction methods, a wide range of advanced extraction technologies is available nowadays for the recovery of these bioactive ingredients from mushrooms, such as ultrasonic-assisted extraction (UAE), microwave-assisted extraction (MAE), enzyme-assisted extraction (EAE), ultrasonic-microwave synergistic extraction (UMSE), subcritical water extraction (SWE), pulsed electric field-assisted extraction (PEFAE), aqueous two-phase extraction (ATPE), integrated extraction techniques, and other novel extraction technologies. This review describes the background of edible mushrooms, followed by the structural characteristics and biological activities of mushroom-derived polysaccharides. Then, the recent developments in the technologies used for the extraction of mushroom polysaccharides are discussed and summarized, together with their strengths and limitations as well as the underlying mechanisms. Finally, these advanced extraction techniques are compared and critically analyzed. Future outlook has also been proposed.

Biovalorization of soybean residue (okara) via fermentation with Ganoderma lucidum and Lentinus edodes to attain products with high anti-osteoporotic effects.

Okara, despite being a soybean processing by-product, still holds many nutrients. Thus, considerable attention has been recently paid to its reuse. In this study, solid-state fermentation was performed using Ganoderma lucidum and Lentinus edodes. Antioxidant activity and bioactive compound levels in G. lucidum-fermented okara (GLFO) and L. edodes-fermented okara (LEFO) were assayed. Antiosteoporosis bioactivity was evaluated using an animal model. The results demonstrated that solid-state fermentation significantly improved the antioxidant activity and bioactive compound levels. Furthermore, GLFO and LEFO increased trabecular bone volume, although only the GLFO-treated group exhibited significantly improved trabecular separation compared with the bilateral ovariectomy-treated control group. GLFO-related outcomes were superior to those of LEFO. The results demonstrate that okara products are effective for treating postmenopausal osteoporosis in humans.

Enhanced production of triterpenoid in submerged cultures of Antrodia cinnamomea with the addition of citrus peel extract.

In recent years, Antrodia cinnamomea has become a well-known medicinal mushroom in Taiwan. Triterpenoids are considered one of the most biologically active components found in A. cinnamomea. The aim of this research is to investigate the feasibility of enhancing triterpenoid production in shake flask cultures of A. cinnamomea by adding citrus peel extract. As a result of its containing essential oils, citrus peel extract is inhibitory to mycelial growth. In the experiments, the appropriate adding time is determined to be on day 7. Of the various citrus peel extracts tested, tangerine proves to be the most effective in enhancing polyphenol and triterpenoid production. With an addition of 2% (v/v), the content and production of total polyphenols rises from 5.95 mg/g DW of the control and 56.73 mg/L to 23.52 mg/g DW and 224.39 mg/L, respectively, on day 28. The production of triterpenoids also increases from 99.93 to 1,028.02 mg/L, for more than a tenfold increase. An optimal level of tangerine peel additive is determined to be around 4%. Furthermore, when compared with the mycelia of the control culture, the profiles of the HPLC analysis show that the mycelia cultured with the tangerine-peel addition contain more kinds of triterpenoids. This study demonstrates that the addition of citrus peel extract effectively enhances the production of bioactive metabolites in the submerged cultures of A. cinnamomea.

Establishment of cultivating strategy for highly aggregated mycelia of Morchella esculenta in a stirred-tank bioreactor.

Mycelia of Morchella esculenta were found to aggregate rapidly in a submerged culture, which caused the decrease in dispersed mycelia and the problem of diffusion limitation. The effect of different agitation schemes on the growth of mycelia was investigated in a stirred-tank bioreactor. At the constant speed of 100 or 300 rpm, rapid aggregation caused the biomass concentration to drop to zero in 30 h, which was even worse than achieved under static culture. Intermittent agitation maintained a higher mycelium fragment concentration for 48 h and enhanced the biomass concentration to 4.73 g/L at 120 h. The operation with a polytron connection disrupted effectively mycelium aggregation, thus increasing the specific growth rate, biomass concentration and maximum productivity to 0.0613 1/h, 7.73 g/L and 0.0878 g/L h at 88 h, respectively. Moreover, logistic equations and genetic algorithm (GA) were used for the simulation of biomass growth and estimation of all kinetic coefficients. The operating strategy developed in this study could be used for the production of highly aggregated mycelia, which could also achieve a high cell-density culture in a stirred tank reactor.

Medium modification to enhance the formation of bioactive metabolites in shake flask cultures of Antrodia cinnamomea by adding citrus peel extract.

Antrodia cinnamomea has recently become a well-known medicinal mushroom in Taiwan. Bioactive compounds found in A. cinnamomea include: polysaccharide, sesquiterpene lactone, steroids and triterpenoids. The aim of this study was to evaluate the feasibility of adding citrus peel extract to enhance the formation of bioactive metabolites in the submerged culture of A. cinnamomea. With the exception of grapefruit, citrus peel extracts tested were proved to be beneficial to mycelial growth and to the production of intracellular polysaccharide. Lemon was the most effective for enhancing bioactive metabolite production. With an addition of 2% (v/v), the mycelium biomass concentration and intracellular polysaccharide content rose from 11.96 g DW/L of the control and 123.6 mg/g DW to 21.96 g DW/L and 230.8 mg/g DW, respectively, on day 8. The production of triterpenoids also increased from 86.7 to 282.9 mg/L. Moreover, this study also demonstrates that although the addition of peel extract could cause the lengthening of the exponential phase and reduce the specific growth rate, the production rate of biomass, intracellular polysaccharide and triterpenoids was still enhanced significantly.

Reusing soy residue for the solid-state fermentation of Ganoderma lucidum.

Lingzhi has been a popular oriental medicine used to treat various human diseases. Soy residue from the waste of tofu manufacturing was used to culture Ganoderma lucidum in solid-state fermentation. The solid-state fermentation was conducted in three types of containers: test tube, 500-ml flask, and sterilize-able polypropylene plastic bag. The highest rate of mycelial growth of 6 mm/day was observed in the medium of carbon/nitrogen (C/N) ratio of 80 using test tubes. However, a growth rate of 7.5 mm/day was found at the C/N ratio of 70-80 in the 500-ml flasks. In the tests using plastic bags, the fruiting bodies were fully developed only for the C/N ratios of 70 and 80. The components of fruiting bodies obtained from different media were also analyzed and compared. The contents of ash, polysaccharides, and crude protein of fruiting bodies were found higher in the media of C/N ratio of 80.