Evaluation of Biomass and Chitin Production of Morchella Mushrooms Grown on Starch-Based Substrates

First report of Morchella galilaea, an autumn species from Pakistan, based on multilocus DNA sequences, light microscopy, and scanning electron microscopy analyses

Morchella is highly prized for its distinct and delicious taste, making it one of the most sought-after and valuable macrofungi. Despite Pakistan exporting morels to various European countries, Morchella's diversity in this South Asian country has not been cataloged using multilocus DNA sequence data. Realizing the need for their scientific identity, various collections were commissioned, including those from the low and high altitudinal zones of the Charsadda, Swat, and Poonch districts of Pakistan during autumn of 2015 through 2019. Specimens were identified by sequencing the internal transcribed spacer (ITS) region and portions of the RNA polymerase II largest subunit (RPB1), second largest subunit (RPB2), and translation elongation factor 1-α (TEF1) loci. Multigene molecular phylogenetic analysis revealed the autumnal collections were Morchella galilaea Masaphy & Clowez. The species was previously documented in the United States, China, Israel, and Turkey. A detailed taxonomic description, light and scanning electron microscopy, and multigene molecular phylogenetic analyses of the species are reported here for the first time from Pakistan. The study underscores the necessity for further surveys of unexplored areas of Pakistan and systematics of Morchella to augment species diversity and their geographic distribution. RESEARCH HIGHLIGHTS: Specimens of Morchella were collected from low and high altitudinal zones in Pakistan during the autumn. Specimens were assessed using multigene (ITS, RPB1, RPB2, and TEF1) molecular phylogenetic analyses for the first time in Pakistan. The specimens were identified as Morchella galilaea based on multigene molecular phylogenetic analysis. Updated taxonomic descriptions of macro- and microanatomical characters were provided for clarity and precision. Hitherto-unreported shapes of paraphyses and acroparaphyses are observed and thoroughly reported. Scanning electron microscopy (SEM) of an ascospore is provided.

New Insights into Sources, Bioavailability, Health-Promoting Effects, and Applications of Chitin and Chitosan

Chitin and chitosan are mostly derived from the exoskeletons of crustaceans, insects, and fungi. Chitin is the second most abundant biopolymer after cellulose, and it is a fibrous polysaccharide which resists enzymatic degradation in the stomach but undergoes microbial fermentation in the colon, producing beneficial metabolites. Chitosan, which is more soluble in the alkaline small intestine, is more susceptible to enzymatic action. Both biopolymers show limited absorption into the bloodstream, with smaller particles exhibiting better bioavailability. The health effects include anti-inflammatory properties, potential in immune system modulation, impacts on cholesterol levels, and antimicrobial effects, with a specific focus on implications for gut health. Chitin and chitosan exhibit anti-inflammatory properties by interacting with immune cells, influencing cytokine production, and modulating immune responses, which may benefit conditions characterized by chronic inflammation. These biopolymers can impact cholesterol levels by binding to dietary fats and reducing lipid absorption. Additionally, their antimicrobial properties contribute to gut health by controlling harmful pathogens and promoting beneficial gut microbiota. This review explores the extensive health benefits and applications of chitin and chitosan, providing a detailed examination of their chemical compositions, dietary sources, and applications, and critically assessing their health-promoting effects in the context of human well-being.

Ganoderma lucidum Mycelia Mass and Bioactive Compounds Production through Grape Pomace and Cheese Whey Valorization

Numerous compounds obtained from the medicinal mushroom Ganoderma lucidum have evidenced renowned bioactive characteristics. Controlled fermentation to generate fungal mycelia confers several advantages, specifically when the valorization of agro-industrial streams as fermentation feedstocks is included. Submerged fermentation of a newly isolated Greek strain of G. lucidum was performed using conventional synthetic media and, also, grape pomace extract (GPE) and cheese whey permeate (CWP) under static and shaking conditions. Under shaking conditions, maximum biomass with GPE and supplementation with organic nitrogen reached 17.8 g/L. The addition of an elicitor in CWP resulted in a significant improvement in biomass production that exceeded synthetic media. Overall, agitation demonstrated a positive impact on biomass productivity and, therefore, on process optimization. Crude intracellular and extracellular polysaccharides were extracted and evaluated regarding antioxidant activity and polysaccharide and protein content. FTIR analysis confirmed the preliminary chemical characterization of the crude extracts. This study introduces the design of a bioprocessing scenario to utilize food industry by-products as onset feedstocks for fungal bioconversions to obtain potential bioactive molecules within the concept of bioeconomy.

Safe Production Strategies for Soil-Covered Cultivation of Morel in Heavy Metal-Contaminated Soils

Morel is a popular edible mushroom with considerable medicinal and economic value which has garnered global popularity. However, the increasing heavy metal (HM) pollution in the soil presents a significant challenge to morels cultivation. Given the susceptibility of morels to HM accumulation, the quality and output of morels are at risk, posing a serious food safety concern that hinders the development of the morel industry. Nonetheless, research on the mechanism of HM enrichment and mitigation strategies in morel remains scarce. The morel, being cultivated in soil, shows a positive correlation between HM content in its fruiting body and the HM content in the soil. Therefore, soil remediation emerges as the most practical and effective approach to tackle HM pollution. Compared to physical and chemical remediation, bioremediation is a low-cost and eco-friendly approach that poses minimal threats to soil composition and structure. HMs easily enriched during morels cultivation were examined, including Cd, Cu, Hg, and Pb, and we assessed soil passivation technology, microbial remediation, strain screening and cultivation, and agronomic measures as potential approaches for HM pollution prevention. The current review underscores the importance of establishing a comprehensive system for preventing HM pollution in morels.

Molecular and cultural characterization of Morchella spp. from disturbed environments of central-southern Chile

In Northwestern Patagonia (Chile), three species of Morchella from undisturbed environments have been identified to date: Morchella tridentina, Morchella andinensis and Morchella aysenina, all belonging to the Elata clade and associated mainly with Nothofagus forests. In this study, the search for Morchella specimens was extended to disturbed environments in Central-Southern Chile, to further explore Morchella species diversity in the country, which is still very limited. The Morchella specimens were identified through multilocus sequences analysis, and the mycelial cultures were characterized, establishing comparisons with specimens from undisturbed environments. To the best of our knowledge, these results reveal for the first time in Chile the presence of the species Morchella eximia and Morchella importuna, and in the case of the last one also the first record in South America. These species were found associated almost exclusively with harvested or burned coniferous plantations. The in vitro mycelial characterization revealed certain inter- and intra-specific patterns of the morphology, such as pigmentation, mycelium type, and development and formation of sclerotia, which varied according to growth media and incubation temperature. The growth rates (mm/day) and mycelial biomass (mg) were significantly influenced by the temperature (p < 0.05), with maximum rates (>10 mm/day) and biomass (approx. 20 mg) between 20 and 24 °C, while a significant growth reduction (70-90%) was observed at 28 °C, mainly in the species from undisturbed environments. Potato-dextrose (PDA) medium stimulated the greatest mycelial density and sclerotia formation in most of the isolates, mainly in M. eximia (UDEC-LAF 236 isolate) which recorded the best mycelial growth performance. Among isolates, UDEC-LAF 236 also showed the best performance in sclerotia production (>350 sclerotia/dish) in 10 days of growth. This study contributes to the knowledge of the diversity of Morchella species in Chile by broadening the species range to those from disturbed environments. It also provides molecular and morphological characterization of the in vitro cultures of different Morchella species. The report on M. eximia and M. importuna, species known as cultivable, adapted to local climatic and edaphic conditions could represent the first step to developing artificial Morchella cultivation methods in Chile.

Ultrastructure and Physiological Characterization of Morchella Mitospores and Their Relevance in the Understanding of the Morel Life Cycle

Morels, which belong to the Ascomycete genus Morchella, are highly valued edible fungi treasured by gourmet chefs worldwide. Some species are saprotrophic and others are able to form facultative mycorrhizal-like associations with plant roots without establishing true ectomycorrhizal symbioses. In general, it is considered that the formation of asexual spores, or mitospores, is an important step in the life cycle of morels. However, ultrastructure characterization and physiological attributes of morel mitospores have received little attention. In this contribution, the mitospores of M. sextelata were successfully induced under laboratory conditions and their ultrastructure, occurrence, germination, physiological characteristics and mating type gene structure were studied. Mitospore production was closely related to aeration, nutrition and humidity conditions. The average germination rate of mitospores on different media and under various induction stimuli was very low, with an average of 1/100,000. Based on the ultrastructure characterization, low germination rate, growth rate decline, rapid aging and mating genotyping, it was concluded that the mitospores of M. sextelata had lost their conventional function as conidia and might act more as mate sperm-like (gamete) structures. Thus, this study contributed to a deeper understanding of the life cycle of the economically and ecologically important morel fungal group.

Heterologous Expression of a Thermostable Chitinase from Myxococcus xanthus and Its Application for High Yield Production of Glucosamine from Shrimp Shell

Glucosamine (GlcN) is a widely used food supplement. Hence, enormous attention has been concerned with enzymatic production of GlcN owing to its advantage over a chemical approach. In this study, a previously unstudied chitinase gene (MxChi) in the genome of Myxococcus xanthus was cloned, expressed in recombinant soluble form and purified to homogeneity. TLC-, UPLC-, and microplate-reader- based activity tests confirmed MxChi hydrolyzes colloidal chitin to chitobiose as sole product. The optimal catalytic pH and temperature of MxChi was identified as 7.0 and 55 °C, respectively. MxChi exhibited 80% activity after 72 h incubation at 37 °C. The site-directed mutagenesis revealed that the amino acids D323A, D325A, and E327A of MxChi were in the DXDXE catalytic motif of GH18. When coupled with β-N-acetylhexosaminidase (SnHex) and deacetylase (CmCBDA), the enzyme allowed one-pot extraction of GlcN from colloidal chitin and shrimp shell. The optimal condition was 37 °C, pH 8.0, and 1/3/16.5 (MxChi/SnHex/CmCBDA), conducted by orthogonal design for the enzymatic cascades. Under this condition, the yield of GlcN was 26.33 mg from 400 mg shrimp shell. Facile recombinant in E. coli, robust thermostability and pure product herein makes newly discovered chitinase a valuable candidate for the green recycling of chitin rich waste.

Bioactive components of mushrooms: Processing effects and health benefits

Mushrooms have been recognized for their culinary attributes for long and were relished in the most influential civilizations in history. Currently, they are the focus of renewed research because of their therapeutic abilities. Nutritional benefits from mushrooms are in the form of a significant source of essential proteins, dietary non-digestible carbohydrates, unsaturated fats, minerals, as well as various vitamins, which have enhanced its consumption, and also resulted in the development of various processed mushroom products. Mushrooms are also a crucial ingredient in traditional medicine for their healing potential and curative properties. The literature on the nutritional, nutraceutical, and therapeutic potential of mushrooms, and their use as functional foods for the maintenance of health was reviewed, and the available literature indicates the enormous potential of the bioactive compounds present in mushrooms. Future research should be focused on the development of processes to retain the mushroom bioactive components, and valorization of waste generated during processing. Further, the mechanisms of action of mushroom bioactive components should be studied in detail to delineate their diverse roles and functions in the prevention and treatment of several diseases.

Estimation of glucosamine in biomass of Trichoderma reesei cultivated on lignocellulosic substrates

Effects of the compositions of lignocellulosic substrate including hemicellulose, cellulose, lignin, and protein on the glucosamine content in biomass of Trichoderma reesei TISTR3080 were studied. A synthetic solid surface media containing different ratios of xylan (hemicellulose), carboxymethyl cellulose (cellulose), lignin, and various concentrations of yeast extract (source of protein) were used to cultivated T. reesei. Regression analysis identified significant individual and interaction factors that affected glucosamine quantity in T. reesei biomass. A regression model was developed to estimate the glucosamine content in biomass of T. reesei from the compositions of the lignocellulosic substrate. An acceptable error (not more than 10%) of the regression model was obtained from validation with the experimental results of glucosamine content in biomass of T. reesei cultivated on lignocellulosic solid surface media made from copra waste and banana peel.

Valorization of low-cost, carbon-rich substrates by edible ascomycetes and basidiomycetes grown on liquid cultures

Three ascomycetes (Morchella vulgaris AMRL 36, M. elata AMRL 63, Tuber aestivum AMRL 364) and four basidiomycetes strains (Lentinula edodes AMRL 124 and 126, Agaricus bisporus AMRL 208 and 209) were screened for their ability to grow on liquid static flask cultures of glucose, glycerol, molasses and waste flour-rich hydrolysates with C/N ratio of 20 and produce biomass, exopolysaccharides and lipids. The profile of lipid fatty acids was also assessed. Selected strains were furthermore cultivated in C/N = 50. Results showed that substrate consumption, biomass formation and secondary metabolites production were strain, substrate and C/N ratio dependent. The maximum biomass (X), lipid (L) and exopolysaccharides (EPS) values noted were Xmax = 25.2 g/L (C/N = 20; molasses) and Lmax = 6.51 g/L (C/N = 50; rice cereal hydrolysates) by T. aestivum strain AMRL 364 and EPSmax = 2.41 g/L by M. elata strain AMRL 63 (C/N = 50; molasses), respectively. When C/N ratio of 50 was applied, biomass, lipid production and substrate consumption seem to be negatively affected in most of the trials. The adaptation and capability of the mushroom strains to be cultivated on substrates based on agro-industrial waste streams and infant food of expired shelf date offers the opportunity to set a circular oriented bioprocess.

Growth kinetics of Myceliophthora thermophila M.7·7 in solid-state cultivation

AIMS

This work aimed to estimate the growth of Myceliophthora thermophila M.7·7 in solid-state cultivation (SSC) through quantification of N-acetyl-d-glucosamine (NAG) and enzyme activity.

METHODS AND RESULTS

The fungus was cultivated in sugarcane bagasse and wheat bran. A consistent statistical analysis was done to assess the reliability of experimental data. Logistic model equation was fitted to experimental data and growth parameters were estimated. The results showed strong influence of the sample size on NAG and a minimum recommended sample size was identified. Scanning electron microscopy (SEM) was used to identify the strategy of substrate colonization. Wheat bran was attacked firstly, while sugarcane bagasse was consumed after wheat bran depletion. The biomass growth was poorly estimated by secretion kinetics of α-amylase, endoglucanase, protease and xylanase, but enzyme kinetics were important for understanding substrate colonization.

CONCLUSIONS

In conclusion, the NAG concentration was strongly affected by the sample size and sampling procedure. The strategy of fungal colonization on the substrates was well characterized through SEM analysis. The colonization strategy has direct influence on the kinetic parameters of the logistic model. Myceliophthora thermophila has a well-defined dynamic of enzyme secretion to degrade the substrate, although the kinetics of enzyme secretion has shown not adequate to characterize the kinetics of fungal growth.

SIGNIFICANCE AND IMPACT OF THE STUDY

The paper provides reliable growth kinetic parameters in the SSC of the cellulase producer fungus M. thermophila M.7·7, as well as a robust analysis on three indirect methods (NAG, enzymes and SEM) for estimation of fungal development.

Spent mushroom substrate for a second cultivation cycle of Pleurotus mushrooms and dephenolization of agro-industrial wastewaters

Spent mushroom substrate (SMS) of Pleurotus ostreatus was supplemented with wheat bran and soybean flour and used as substrate for a new cultivation cycle of the oyster mushrooms Pleurotus ostreatus and Pleurotus pulmonarius. The bioconversion efficiency of mushrooms produced over substrate (BE%) used and the chemical composition of sporophores were evaluated. The concentration of mycelial mass, crude exopolysaccharide content and laccase enzyme activity were also determined at the supplemented SMS before inoculation, at 50% and 100% of colonization stages in the new cultivation and in the final re-utilized SMS. The laccase enzyme was extracted to examine SMS potential for the dephenolization of olive mill and winery wastewaters. Results showed that both Pleurotus species exhibited BE over 185%, demonstrating this bioprocess could represent a promising strategy to convert SMS into nutritional food. Data also indicate the strong positive impact that SMS could have in the solid wastes’ management and agribusiness enhancement.

Molecular Mechanism of Functional Ingredients in Barley to Combat Human Chronic Diseases

Barley plays an important role in health and civilization of human migration from Africa to Asia, later to Eurasia. We demonstrated the systematic mechanism of functional ingredients in barley to combat chronic diseases, based on PubMed, CNKI, and ISI Web of Science databases from 2004 to 2020. Barley and its extracts are rich in 30 ingredients to combat more than 20 chronic diseases, which include the 14 similar and 9 different chronic diseases between grains and grass, due to the major molecular mechanism of six functional ingredients of barley grass (GABA, flavonoids, SOD, K-Ca, vitamins, and tryptophan) and grains (β-glucans, polyphenols, arabinoxylan, phytosterols, tocols, and resistant starch). The antioxidant activity of barley grass and grain has the same and different functional components. These results support findings that barley grain and its grass are the best functional food, promoting ancient Babylonian and Egyptian civilizations, and further show the depending functional ingredients for diet from Pliocene hominids in Africa and Neanderthals in Europe to modern humans in the world. This review paper not only reveals the formation and action mechanism of barley diet overcoming human chronic diseases, but also provides scientific basis for the development of health products and drugs for the prevention and treatment of human chronic diseases.

Cheese Whey Processing: Integrated Biorefinery Concepts and Emerging Food Applications

Cheese whey constitutes one of the most polluting by-products of the food industry, due to its high organic load. Thus, in order to mitigate the environmental concerns, a large number of valorization approaches have been reported; mainly targeting the recovery of whey proteins and whey lactose from cheese whey for further exploitation as renewable resources. Most studies are predominantly focused on the separate implementation, either of whey protein or lactose, to configure processes that will formulate value-added products. Likewise, approaches for cheese whey valorization, so far, do not exploit the full potential of cheese whey, particularly with respect to food applications. Nonetheless, within the concept of integrated biorefinery design and the transition to circular economy, it is imperative to develop consolidated bioprocesses that will foster a holistic exploitation of cheese whey. Therefore, the aim of this article is to elaborate on the recent advances regarding the conversion of whey to high value-added products, focusing on food applications. Moreover, novel integrated biorefining concepts are proposed, to inaugurate the complete exploitation of cheese whey to formulate novel products with diversified end applications. Within the context of circular economy, it is envisaged that high value-added products will be reintroduced in the food supply chain, thereby enhancing sustainability and creating "zero waste" processes.

Upgrading Grape Pomace through Pleurotus spp. Cultivation for the Production of Enzymes and Fruiting Bodies

Grape pomace, a by-product derived from winery industries, was used as fermentation media for the production of added-value products through the cultivation of two Pleurotus species. Solid-state (SSF), semiliquid (SLF), and submerged (SmF) fermentations were carried out using grape pomace as substrate. The effect of the different fermentations on the consumption of phenolic compounds, the production of mycelial mass and enzymes was evaluated using P. ostreatus and P. pulmonarius. The production of fungal biomass and enzymes was influenced by the fermentation mode. The maximum biomass values of ~0.5 g/g were obtained for both P. pulmonarius and P. ostreatus in SmF. Laccase production was induced in SSF and a maximum activity of 26.247 U/g was determined for P. ostreatus, whereas the highest endoglucanase activity (0.93 U/g) was obtained in the SmF of the same fungi. Analysis of phenolic compounds showed that both strains were able to degrade up to 79% of total phenolic content, regardless the culture conditions. Grape pomace was also evaluated as substrate for mushroom production. P. pulmonarius recorded the highest yield and biological efficiency of 14.4% and 31.4%, respectively. This study showed that mushroom cultivation could upgrade winery by-products towards the production of valuable food products.