Characteristics of Exopolysaccharides from the Citrine Oyster Mushroom, Pleurotus citrinopileatus (Agaricomycetes), Depend on the Nitrogen Source in the Medium.[Pubmed: 30055556]

We investigated the effect of peptone and (NH4)2SO4, used as nitrogen sources in a submerged medium, on the molecular weight and carbohydrate compositions of exopolysaccharides (EPSs) produced by the culinary-medicinal mushroom Pleurotus citrinopileatus. When (NH4)2SO4 was used instead of peptone, it yielded more specific EPSs, producing 32.80 mg EPS/g dry mycelial biomass, but small amounts of EPS and mycelial biomass. These nitrogen sources also resulted in the production of different net charged EPSs, according to crude fractionations on a DEAE Sepharose Fast Flow column. Purified EPSs were initially repurified by gel filtration chromatography, and the profiles indicated that a range of EPSs with different molecular weights were collected through the use of this strategy. Analysis of the carbohydrate composition of purified EPSs demonstrated that the main component produced by P. citrinopileatus in a glucose-(NH4)2SO4 medium, with an estimated molecular weight < 10 kDa, was rich in glucose (95.9%), and its structure could consist of glucan. Conversely, this mushroom produced diverse heteropolysaccharides (11.1-42.3% mannose, 6.3-80.3% glucose, 0.3-49.2% N-acetylgalactosamine, and 7.6-26.3% N-acetylglucosamine) in a glucose-peptone submerged medium. By applying various nitrogen sources in submerged medium, these results could be used to improve the possibility of obtaining molecules similar to those found in the fruiting bodies of the same mushroom species grown in conventional culture.

Comparative mitogenomics reveals large-scale gene rearrangements in the mitochondrial genome of two Pleurotus species.[Pubmed: 29799088]

In the present study, we assembled the mitogenomes of Pleurotus citrinopileatus and Pleurotus platypus. The circular mitogenome of the two Pleurotus species comprises a set of 14 conserved protein-encoding genes (PEGs), 2 RNA genes (small subunit ribosomal RNA and large subunit ribosomal RNA), and 24 tRNAs, with sizes of 60,694 and 73,807 bp, respectively. They contain 4 and 10 introns with 3 and 10 intronic open reading frames (ORFs), respectively. Thirteen position classes (Pcls) of introns were found in the cox1 gene of four Pleurotus species. The number and class of Pcl varied among different Pleurotus species, indicating that numerous events of loss and gain occurred during evolution of Pleurotus. Comparative mitogenomic and collinearity analyses reveal that large-scale gene rearrangements may have occurred during the evolution of Pleurotus citrinopileatus and Pleurotus platypus, including gene rearrangements and inversions, which may be related to the observed high amounts of repetitive DNA elements (5.62 and 5.45%, respectively). Phylogenetic analysis based on concatenated mitochondrial protein sequences reveals that concatenated mitochondrial genes are suitable as molecular markers for phylogenetic analysis. This serves as the first report on large-scale rearrangements in the mitochondria of the genus Pleurotus, thereby improving our understanding of the evolution of the Pleurotus genus and other macrofungi.

Partially methylated galactans containing different proportions of 3-O-methyl-galactose from Pleurotus citrinopileatus.[Pubmed: 29432964]

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Ethanolic Extract of the Golden Oyster Mushroom, Pleurotus citrinopileatus (Agaricomycetes), Alleviates Metabolic Syndrome in Diet-Induced Obese Mice.[Pubmed: 29345562]

Pleurotus citrinopileatus is an edible medicinal mushroom rich in biomolecules and thus has a high potential for use in formulating pharmaceutical and nutraceutical products. To test its effect on body weight and glucose control, we generated diet-induced obese (DIO) C57BL/6J male mice by feeding the mice a high-fat diet (60% fat) for 8 weeks and treating them with an ethanolic P. citrinopileatus extract (PCE) at either 200 or 500 mg/kg body weight for 12 additional weeks. The results showed that PCE significantly inhibited high-fat diet-induced weight gain, fat accumulation, and glucose intolerance in the DIO mice. Moreover, the PCE had a beneficial effect on liver and kidney function. On the basis of these results, we conclude that PCE is effective in the treatment of metabolic syndrome and thus could be a good candidate for use in future pharmaceutical or nutraceutical applications.

Molecular Weight Affected Antioxidant, Hypoglycemic and Hypotensive Activities of Cold Water Extract from Pleurotus citrinopileatus.[Pubmed: 28850664]

Cold water extract of P. citrinopileatus (CWEPC) was fractioned into 4 fractions, PC-I (<1 kDa), PC-II (1-3.5 kDa), PC-III (3.5-10 kDa), and PC-IV (>10 kDa), by ultrafiltration. The antioxidant activities, the inhibition of pancreatic α-amylase, intestinal α-glucosidase, and hypertension-linked angiotensin converting enzyme (ACE), as well as the contents of polysaccharides, protein, and phenolic compounds of 4 fractions were determined. The results showed that lower MW fractions exerted a higher antioxidant activity, which was correlated to phenolic contents. The high molecular fraction (PC-IV) exhibited significantly higher inhibitory activity on α-amylase, α-glucosidase, and ACE compared to CWEPC and the other 3 lower MW fractions (<10 kDa), which was more related to protein contents. The inhibition capability of CWEPC and PC-IV on α-amylase activity was 1/13.4 to 1/2.7 relative to that of acarbose, respectively. Kinetic data revealed that PC-IV fraction followed a noncompetitive inhibition pattern on α-glucosidase activity. The study demonstrated that various MW fractions and types of components contribute to different biological functions of P. citrinopileatus and it is protein constituents but not peptides responsible for the hypoglycemic potential of CWEPC.

Nonvolatile Taste Components and Antioxidant Properties of Fruiting Body and Mycelium with High Ergothioneine Content from the Culinary-Medicinal Golden Oyster Mushroom Pleurotus citrinopileatus (Agaricomycetes).[Pubmed: 27910787]

Pleurotus citrinopileatus mycelium was prepared with high ergothioneine (Hi-Ergo) content and its proximate composition, nonvolatile taste components, and antioxidant properties were studied. The ergothioneine contents of fruiting bodies and Hi-Ergo and regular mycelia were 3.89, 14.57, and 0.37 mg/g dry weight, respectively. Hi-Ergo mycelium contained more dietary fiber, soluble polysaccharides, and ash but less carbohydrates, reducing sugar, fiber, and fat than regular mycelium. However, Hi-Ergo mycelium contained the smallest amounts of total sugars and polyols (47.43 mg/g dry weight). In addition, Hi-Ergo mycelium showed the most intense umami taste. On the basis of the half-maximal effective concentration values obtained, the 70% ethanolic extract from Hi-Ergo mycelium showed the most effective antioxidant activity, reducing power, and scavenging ability, whereas the fruiting body showed the most effective antioxidant activity, chelating ability, and Trolox-equivalent antioxidant capacity. Overall, Hi-Ergo mycelium could be beneficially used as a food-flavoring material or as a nutritional supplement.