Solid-state cultivation of Grifola frondosa (Dicks: Fr) S.F. Gray biomass and immunostimulatory effects of fungal intra- and extracellular β-polysaccharides

Grifola frondosa polysaccharides: A review on structure/activity, biosynthesis and engineering strategies

Polysaccharides are the main polymers in edible fungi Grifola frondosa, playing a crucial role in the physiology and representing the healthy benefits for humans. Recent efforts have well elucidated the fine structures and biological functions of G. frondosa polysaccharides. The recently-rapid developments and increasing availability in fungal genomes also accelerated the better understanding of key genes and pathways involved in biosynthesis of G. frondosa polysaccharides. Herein, we provide a brief overview of G. frondosa polysaccharides and their activities, and comprehensively outline the complex process, genes and proteins corresponding to G. frondosa polysaccharide biosynthesis. The regulation strategies including strain improvement, process optimization and genetic engineering were also summarized for maximum production of G. frondosa polysaccharides. Some remaining unanswered questions in describing the fine synthesis machinery were also pointed out to open up new avenues for answering the structure-activity relationship and improving polysaccharide biosynthesis in G. frondosa. The review hopefully presents a reasonable full picture of activities, biosynthesis, and production regulation of polysaccharide in G. frondosa.

Preparation and structural analysis of fucomannogalactan and β-1,6-glucan from Grifola frondosa mycelium

Introduction: Polysaccharides, key components present in Grifola frondosa, can be divided into those derived from fruiting bodies, mycelium, and fermentation broth based on their source. The structure of G. frondosa fruiting body-derived polysaccharides has been fully characterized. However, the structure of G. frondosa mycelium-derived polysaccharides remains to be elucidated. Methods: In this study, we obtained mycelia from G. frondosa by liquid fermentation and extracted them with water and alkaline solution. Then, the mycelia were isolated and purified to obtain homogeneity and systematically characterized by methylation and FT infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. Results and discussion: Structural analysis showed that two neutral fractions (WGFP-N-a and AGFP-N-a1) have a common backbone composed of α-1,6-D-Me-Galp and α-1,6-D-Galp that were substituted at O-2 by 1,2-Manp, α-1,3-L-Fucp, and α-T-D-Manp and thus are identified as fucomannogalactans. WGFP-A-a, AGFP-A-b, and AGFP-A-c are β-1,6-glucans with different molecular weights and are branched with β-1,3-D-Glcp and T-D-Glcp at the O-3 of Glc. Our results provide important structural information about G. frondosa mycelium-derived polysaccharides and provide the basis for their further development and application.

Advances in Production of Medicinal Mushrooms Biomass in Solid State and Submerged Bioreactors

Production of mushroom fruit bodies using farming technology could hardly meet the increasing demand of the world market. During the last several decades, there have been various basic and applied studies on fungal physiology, metabolism, process engineering, and (pre)clinical studies. The fundamental aspects of solid-state cultivation of various kinds of medicinal mushroom mycelia in various types of bioreactors were established. Solid-state cultivation of medicinal mushrooms for their biomass and bioactive metabolites production appear very suitable for veterinary use. Development of comprehensive submerged technologies using stirred tank and airlift bioreactors is the most promising technology for fast and large-scale production of medicinal fungi biomass and their pharmaceutically active products for human need. The potentials initiate the development of new drugs and some of the most attractive over-the-counter human and veterinary remedies. This article is to overview the engineering achievements in solid state and submerged cultivations of medicinal mushrooms in bioreactors.

Advances in Pilot-Scale Stirred Bioreactors in Solid-State and Submerged Cultivations of Medicinal Mushrooms

Great interest for large-scale production of medicinal mushroom biomass and various pharmaceutically active compounds production dictates the development of comprehensive technologies. Solid state and submerged cultivations in bioreactors represent the most promising technologies for fast and large amount production of medicinal fungi biomass and pharmaceutically active products for human and veterinary need. There are many stages from shaking culture studies to large-scale industrial production. Pilot-scale studies represent the bridge and the balance between the gap of laboratory and industrial scale. Therefore it is not a surprise that most of pilot-scale results and experiences remain uncovered industrial secrets. This chapter is an overview of available engineering achievements in submerged and solid-state cultivation experiences in pilot-scale bioreactors.

Comparison of Polysaccharides Extracted from Cultivated Mycelium of Inonotus obliquus with Polysaccharide Fractions Obtained from Sterile Conk (Chaga) and Birch Heart Rot

The polysaccharides of the sterile conk of Inonotus obliquus (Chaga) have demonstrated multiple bioactivities. The mycelium of this basidiomycete, obtained after submerged cultivation, has been considered a feasible alternative to the sterile conk for the production of polysaccharides. However, previous research has paid little attention to the differences in the structures of polymers obtained from the different resources. Moreover, the birch wood colonized by I. obliquus has never been investigated as a source of bioactive polysaccharides. In the present study, polysaccharide fractions produced from cultivated mycelium, sterile conks of different geographical origins, and birch heart rot were investigated. High amounts of phenolic compounds, possibly lignans, were bound to the sterile conk polysaccharides. Mycelial polysaccharides were rich in α- and β-glucans and had high (10⁵ Da) and low (10⁴ Da) molecular weight populations. On the other hand, sterile conk polysaccharides were mainly β-glucan of lower and monodispersed molecular weight (10³ Da). Heart rot polysaccharides were comprised mainly of low molecular weight (10³ Da) hemicelluloses. Nevertheless, fungal polysaccharides were identified in the extracts. The differences in structure and molecular properties among the polysaccharide fractions of mycelium, heart rot, and sterile conk are likely associated with differences in bioactivities and, therefore, in nutraceutical potential.

Bioactivity assessment of exopolysaccharides produced by Pleurotus pulmonarius in submerged culture with different agro-waste residues

Pleurotus spp. are white-rot fungi that utilize different agro-wastes to produce useful biologically active compounds. In this study, exopolysaccharides (EPS) were produced by Pleurotus pulmonarius in submerged culture supplemented with different agro-wastes. Functional groups in EPS were revealed using Fourier Transform-Infrared (FT-IR) spectroscopy. Antimicrobial activity of EPS was tested against microorganisms using agar well diffusion. Scavenging potentials of EPS was tested against 1, 1- diphenyl-2-picryhydrazyl (DPPH), hydroxyl (OH), iron (Fe2+) and nitric oxide (NO) radicals. In vitro prebiotic activity of EPS was carried out. The highest yield (5.60 g/L) of EPS was produced by P. pulmonarius in submerged culture supplemented with groundnut shell (20.0 g/L). The functional groups in EPS were hydroxyl (-OH), methyl (-CH3), ketone (-RCOH) and carbonyl group (-C=O). EPS displayed zones of inhibition (5.00-14.00 mm) against tested microorganisms. Scavenging activity of EPS ranged from 65.70-81.80% against DPPH. EPS supported the growth of Lactobacillus delbrueckii and Streptococcus thermophiles with values ranged from 3.04 × 104-3.40 × 104 cfu/ml and 2.50 × 104-2.81 × 104 cfu/ml, respectively. Submerged culture of P. pulmonarius with addition of agro-wastes enhanced yield of EPS. The EPS exhibited bio-functional properties like antimicrobial, antioxidant and prebiotic activities. Hence, agrowastes can be recycled in submerged fermentation with fungi to produce promising biomaterials for biopharmaceutical applications.

Cultivation of Medicinal Mushroom Biomass by Solid-State Bioprocessing in Bioreactors

Basidiomycetes of various species and their wide range of pharmaceutically interesting products in the last decades represent one of the most attractive groups of natural products in Asia and North America. Production of fungal fruit bodies using farming technology is hardly covering the market. Comprehensive solid-state technologies and bioreactors are the most promising part for fast and large amount of cultivation of medicinal fungi biomass and its pharmaceutically active products. Wood, agriculture, and food industry wastes represent the main substrates that are in this process delignified and enriched in proteins and highly valuable pharmaceutically active compounds. Research in physiology, basic and applied studies in fungal metabolism, process engineering aspects, and clinical studies in the last two decades represent large contribution to the development of these potentials that initiate the development of new drugs and some of the most attractive over-the-counter human and veterinary remedies. Present article is an overview of the achievements in solid-state technology of the most relevant medicinal mushroom species production in bioreactors. Graphical Abstract.

Valorization of spent oyster mushroom substrate and laccase recovery through successive solid state cultivation of Pleurotus, Ganoderma, and Lentinula strains

Spent mushroom substrate (SMS) of Pleurotus ostreatus was supplemented with wheat bran and soybean flour in various proportions to obtain C/N ratios of 10, 20, and 30, and their effect was evaluated in successive cultivation of Pleurotus ostreatus, Pleurotus pulmonarius, Ganoderma adspersum, Ganoderma resinaceum, and Lentinula edodes strains with respect to mycelium growth rate, biomass concentration, recovery of the enzyme laccase and crude exopolysaccharides, and also with additional fruiting body production. All fungi showed the highest growth rate on unamended SMS (C/N 30), with G. resinaceum being the fastest colonizer (Kr = 9.84 mm day-1), while biomass concentration maximized at C/N 10. Moreover, supplementation affected positively laccase activity, with P. pulmonarius furnishing the highest value (44,363.22 U g-1) at C/N 20. On the contrary, L. edodes growth, fruiting, and laccase secretion were not favored by SMS supplementation. Fruiting body formation was promoted at C/N 30 for Ganoderma and at C/N 20 for Pleurotus species. Exopolysaccharide production of further studied Pleurotus strains was favored at a C/N 20 ratio, at the initial stage of SMS colonization. The obtained results support the potential effective utilization of supplemented SMS for laccase production from Ganoderma spp. and for new fruiting body production of Pleurotus spp.

Immunomodulatory Properties of Filamentous Fungi Cultivated through Solid-State Fermentation on Rapeseed Meal

Water extracts from solid-state fermentation (SSF) on rapeseed meal using filamentous fungi exhibit interesting immunomodulatory activities in vitro. Immunomodulation was determined by the capacity of the compounds to activate blood neutrophils and to influence cytokine production in human peripheral blood mononuclear cells (PBMC) and mouse bone marrow-derived macrophages (BMDM). Among the strains tested, Aspergillus sojae mycelium and SSF extracts were the most promising in terms of enhancing the immune response. The filamentous fungus was also successfully cultivated in a pre-pilot bioreactor with forced aeration. The results indicated that the extracts not only activated blood neutrophils but also significantly modulated IL-1β cytokine levels with lipopolysaccharide (LPS)-stimulated PBMC and BMDM without any cytotoxicity in immune cells. IL-1β was down-regulated in a dose-dependent manner in the presence of A. sojae crude mycelium and SSF extract with PBMC, which indicated that there was an anti-inflammatory activity, whereas IL-1β secretion was up-regulated in the presence of stimulated BMDM with the highest concentration that was tested (100 μg/mL). The non-fermented rapeseed had no effect at the same concentration. SSF culture, as a natural product, may be a good source for the development of functional feed with an immunostimulating effect or could potentially be used in medicinal applications.

Isolation, purification, structural analysis and immunostimulatory activity of water-soluble polysaccharides from Grifola Frondosa fruiting body

A new polysaccharide had been successfully isolated from maitake mushroom (Grifola Frondosa)-GFP. HPLC and Monosaccharide analysis showed that the average molecular weight of GFP was 155kDa and it was mainly composed of rhamnose, xylose, mannose, glucose, molar ratio of 1.00: 1.04: 1.11: 6.21. FTIR, methylation analysis and NMR were used to analyze the structural characterization of GFP. Structural analysis results revealed that its backbone consisted of (1→4)-linked methylation, Glcp residues were major structural polysaccharide GFP units, accounting of the polysaccharide backbone speculate GFP every→3)-Glcp-(1→and one→3,4)-Glcp-(1→connected interval with a small amount of 1→, 1→4, 1→6 glycosidic linkage. MTT assay showed that GFP could significantly improve the proliferation activity of RAW264.7 cells in a certain range of concentrations and time. Scanningelectro microscopy (SEM) results indicated that GFP could induce RAW264.7 cells activation. GFP could obviously increase the proliferation index and enhance the immunostimulatory activity such as the cytokine and chemokine production.

Optimization of subcritical water extraction of polysaccharides from Grifola frondosa using response surface methodology

BACKGROUND

This research is among the few that has been conducted on the feasibility of subcritical water extraction (SWE) as a rapid and efficient extraction tool for polysaccharides.

OBJECTIVE

The aim of the study was to extractand optimize the parameter conditions of SWE of polysaccharides from Grifola frondosa using response surface methodology.

MATERIALS AND METHODS

In the study, SWEwas applied to extractbioactive compounds from G. frondosa. A preliminary analysis was made on the physical properties and content determination of extracts using SWE and hot water extraction (HWE). Analysis of the sample residues and antioxidant activities of the polysaccharides extracted by SWE and HWE were then evaluated.

RESULTS

THE OPTIMAL EXTRACTION CONDITIONS INCLUDE: extraction temperature of 210°C, extraction time of 43.65 min and the ratio of water to raw material of 26.15:1. Under these optimal conditions, the experimental yield of the polysaccharides (25.1 ± 0.3%) corresponded with the mean value predicted by the model and two times more than the mean value obtained by the traditional HWE. The antioxidant activities of polysaccharides extracted by SWE were generally higher than those extracted by HWE. From the study, the SWE technology could be a time-saving, high yield, and bioactive technique for production of polysaccharides.