Molecular properties of water-unextractable proteoglycans from Hypsizygus marmoreus and their in vitro immunomodulatory activities

Evaluation of the nutritional value, umami taste, and volatile organic compounds of Hypsizygus marmoreus by simulated salivary digestion in vitro

Hypsizygus marmoreus is an edible medicinal mushroom species with a high dietary value. The main purpose of this study was to evaluate the nutritional value, umami taste, and volatile organic compounds (VOCs) of H. marmoreus treated with hot water combined with simulated salivary digestion in vitro. Seafood mushroom (Hm3) had the highest content of moisture, soluble polysaccharides, soluble proteins, and total flavonoids while white Hypsizygus marmoreus (Hm1) had the highest total phenolic content. Moreover, Hm1 had a more noticeable equivalent umami concentration (EUC) value, indicating the umami properties of Hm1 as a food or processing ingredient. Results from E-nose and HS-SPME-GC-MS revealed that the VOCs of Hm1 and brown Hypsizygus marmoreus (Hm2) were relatively similar, which differed substantially from Hm3. Among the 134 VOCs, 24 differential metabolites were identified by OPLS-DA analysis, characterized by VIP > 1, p-value < 0.05, and FC > 2 (pairwise comparisons). Furthermore, 10 biomarkers with VIP > 1 and p-value < 0.05 were identified by PLS-DA analysis based on the total differential metabolites to distinguish different strains of H. marmoreus. These results will benefit future research on the chemistry of H. marmoreus and serve as a guide for breeding, introducing, and using the species more effectively.

Comparative Proteomic Analyses within Three Developmental Stages of the Mushroom White Hypsizygus marmoreus

(1) Background: The Hypsizygus marmoreus is a popular edible mushroom in East Asian markets. In a previous study, we reported the proteomic analyses of different developmental stages of H. marmoreus, from primordium to mature fruiting body. However, the growth and protein expression changes from scratching to primordium are unclear. (2) Methods: A label-free LC-MS/MS quantitative proteomic analysis technique was adopted to obtain the protein expression profiles of three groups of samples collected in different growth stages from scratching to the tenth day after scratching. The Pearson's correlation coefficient analysis and principal component analysis were performed to reveal the correlation among samples. The differentially expressed proteins (DEPs) were organized. Gene Ontology (GO) analysis was performed to divide the DEPs into different metabolic processes and pathways. (3) Results: From the 3rd day to the 10th day after scratching, mycelium recovered gradually and formed primordia. Compared with the Rec stage, 218 highly expressed proteins were identified in the Knot stage. Compared with the Pri stage, 217 highly expressed proteins were identified in the Rec stage. Compared with the Pri stage, 53 highly expressed proteins were identified in the Knot stage. A variety of the same highly expressed proteins were identified in these three developmental stages, including: glutathione S-transferase, acetyltransferase, importin, dehydrogenase, heat-shock proteins, ribosomal proteins, methyltransferase, etc. The key pathways in the development of H. marmoreus are metabolic process, catabolic process, oxidoreductase activity and hydrolase activity. DEPs in the Knot or Pri stages compared with the Rec stage were significantly decreased in the metabolic-, catabolic- and carbohydrate-related process; and the oxidoreductase, peptidase, and hydrolase activity, which can serve as targets for selectable molecular breeding in H. marmoreus. A total of 2000 proteins were classified into eight different modules by WGCNA, wherein 490 proteins were classified into the turquoise module. (4) Conclusions: Generally, from the 3rd day to the 10th day after scratching, mycelium recovered gradually and formed primordia. Importin, dehydrogenase, heat-shock proteins, ribosomal proteins, transferases were all highly expressed in these three developmental stages. DEPs in the Rec stage compared with the Knot or Pri stages were significantly enriched in the metabolic-, catabolic- and carbohydrate-related process; and in oxidoreductase, peptidase and hydrolase activities. This research contributes to the understanding of the mechanisms of the development changes before primordium of H. marmoreus.

Comparative Proteomic Analysis within the Developmental Stages of the Mushroom White Hypsizygus marmoreus

(1) Background: The white Hypsizygus marmoreus is a popular edible mushroom in East Asia markets. Research on the systematic investigation of the protein expression changes in the cultivation process of this mushroom are few. (2) Methods: Label-free LC-MS/MS quantitative proteomics analysis technique was adopted to obtain the protein expression profiles of six groups of samples collected in different growth stages. A total of 3468 proteins were identified. The UpSetR plot analysis, Pearson correlation coefficient (PCC) analysis, and principal component (PC) analysis were performed to reveal the correlation among the six groups of samples. The differentially expressed proteins (DEPs) were organised by One-way ANOVA test and divided into four clusters. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed to divide the DEPs into different metabolic processes and pathways in each cluster. (3) Results: The DEPs in cluster 1 are of the highest abundance in the mycelium and are mainly involved in protein biosynthesis, biosynthesis of cofactors, lipid metabolism, spliceosome, cell cycle regulation, and MAPK signaling pathway. The DEPs in cluster 2 are enriched in the stem and are mainly associated with protein biosynthesis, biosynthesis of cofactors, carbon, and energy metabolism. The DEPs in cluster 3 are highly expressed in the primordia and unmatured fruiting bodies and are related to amino acids metabolism, carbon and carbohydrate metabolism, protein biosynthesis and processing, biosynthesis of cofactors, cell cycle regulation, MAPK signaling pathway, ubiquitin-mediated proteolysis, and proteasome. The DEPs in cluster 4 are of the highest abundance in the cap and are mainly associated with spliceosome, endocytosis, nucleocytoplasmic transport, protein processing, oxidative phosphorylation, biosynthesis of cofactors, amino acids metabolism, and lipid metabolism. (4) Conclusions: This research reports the proteome analysis of different developmental stages during the cultivation of the commercially relevant edible fungi the white H. marmoreus. In the mycelium stage, most of the DEPs are associated with cell proliferation, signal response, and mycelium growth. In the primordia and unmatured fruiting bodies stage, the DEPs are mainly involved in biomass increase, cell proliferation, signal response, and differentiation. In the mature fruiting body stage, the DEPs in the stem are largely associated with cell elongation and increase in biomass, and most of the DEPs in the cap are mainly related to pileus expansion. Several carbohydrate-active enzymes, transcription factors, heat shock proteins, and some DEPs involved in MAPK and cAMP signaling pathways were determined. These proteins might play vital roles in metabolic processes and activities. This research can add value to the understanding of mechanisms concerning mushroom development during commercial production.

Macrophage activation by edible mushrooms is due to the collaborative interaction of toll-like receptor agonists and dectin-1b activating beta glucans derived from colonizing microorganisms

Research supports the theory that the microbiome of plants and mushrooms produce potent activators of pathogen recognition receptors which are principal contributors to the stimulation of macrophages. We have previously reported that the in vitro macrophage stimulatory activity of water-soluble extracts from 13 different types of edible mushrooms is predominantly due to bacterial components originating from the naturally occurring bacterial communities within these materials. The purpose of the current study was to further investigate the bacterial-dependent activity of the water-soluble extracts and assess whether these 13 types of mushrooms contain water-insoluble beta glucans that activate the dectin-1b signaling pathway. Activity of the water-soluble extracts was predominantly due to Toll-like receptor 2 (TLR2) and TLR4 agonists. For dectin-1b-dependent activity (indicative of water-insoluble beta glucans), culinary mushrooms (Agaricus bisporus varieties) were essentially inactive, whereas most of the medicinal mushrooms (Lentinula edodes, Grifola frondosa, Hypsizygus marmoreus varieties, Flammulina velutipes) exhibited potent activation. A. bisporus samples with no detectable dectin-1b-dependent activity had yeast colony forming units that were 687 times lower than L. edodes exhibiting high activity, indicating that the active insoluble beta glucans are derived from colonizing yeast. In addition, co-stimulation of macrophages with the TLR agonists and insoluble beta glucan was found to result in a synergistic enhancement of in vitro cytokine production. Taken together, these findings indicate that the in vitro macrophage activating potential of edible mushrooms is due to the collaborative interaction of water-soluble TLR agonists (derived from colonizing bacteria) and water-insoluble beta glucans (derived from colonizing yeast).

Bacterial components are the major contributors to the macrophage stimulating activity exhibited by extracts of common edible mushrooms

Recent studies have indicated that a major contributor to the innate immune enhancing properties of some medicinal plants is derived from the cell wall components of bacteria colonizing these plants. The purpose of the current study was to assess if the bacteria present within edible and medicinal mushrooms substantially contribute to the innate immune stimulating potential of these mushrooms. Whole mushrooms from thirteen types of edible fungi and individual parts from Agaricus bisporus were analyzed for in vitro macrophage activation as well as bacterial lipopolysaccharides (LPS) content, cell load, and community composition. Substantial variation between samples was observed in macrophage activation (over 500-fold), total bacterial load (over 200-fold), and LPS content (over 10 million-fold). Both LPS content (ρ = 0.832, p < 0.0001) and total bacterial load (ρ = 0.701, p < 0.0001) correlated significantly with macrophage activation in the whole mushroom extracts. Extract activity was negated by treatment with NaOH, conditions that inactivate LPS and other bacterial components. Significant correlations between macrophage activation and total bacterial load (ρ = 0.723, p = 0.0001) and LPS content (ρ = 0.951, p < 0.0001) were also observed between different tissues of Agaricus bisporus. Pseudomonas and Flavobacterium were the most prevalent genera identified in the different tissue parts and these taxa were significantly correlated with in vitro macrophage activation (ρ = 0.697, p < 0.0001 and ρ = 0.659, p = 0.0001, respectively). These results indicate that components derived from mushroom associated bacteria contribute substantially to the innate immune enhancing activity exhibited by mushrooms and may result in similar therapeutic actions as reported for ingestion of bacterial preparations such as probiotics.