Edible Oyster Mushroom Research Articles

First report of amphizoic amoebae isolated from edible Oyster mushroom- Pleurotus sajor-caju (Singer, 1949)

The present document serves as the first evidence that describes the presence of amphizoic amoebae in cap, stalk and internal tissues such as gills of the edible Oyster mushrooms, Pleurotus sajor-caju, packaged, and sold for public consumption. Samples tested over a 9 month period from different vegetable markets of Lucknow city revealed that out of 180 mushrooms, 176 (97.77%) yielded amphizoic amoebae, namely, Schizopyrenus, Naegleria, Hartmannella, Acanthamoeba and Vanella sp. Four samples of internal tissues yielded 6 strains of amoebae. A total of 17 Naegleria strains were isolated, out of which 5 were identified as Naegleria fowleri and were tested for their pathogenicity. The strains 2BNf01 and 5BNf04 were mildly pathogenic and strains, 4ANf02i, 4ANf03 and 8ANf05i were highly pathogenic. It was also observed that the most frequently observed species of amoebae belonged to the genus Acanthamoeba and a total 103 Acanthamoeba strains recorded.

Anti-inflammatory activity of edible oyster mushroom is mediated through the inhibition of NF-κB and AP-1 signaling

BackgroundMushrooms are well recognized for their culinary properties as well as for their potency to enhance immune response. In the present study, we evaluated anti-inflammatory properties of an edible oyster mushroom (Pleurotus ostreatus) in vitro and in vivo.MethodsRAW264.7 murine macrophage cell line and murine splenocytes were incubated with the oyster mushroom concentrate (OMC, 0-100 μg/ml) in the absence or presence of lipopolysacharide (LPS) or concanavalin A (ConA), respectively. Cell proliferation was determined by MTT assay. Expression of cytokines and proteins was measured by ELISA assay and Western blot analysis, respectively. DNA-binding activity was assayed by the gel-shift analysis. Inflammation in mice was induced by intraperitoneal injection of LPS.ResultsOMC suppressed LPS-induced secretion of tumor necrosis factor-α (TNF-α, interleukin-6 (IL-6), and IL-12p40 from RAW264.7 macrophages. OMC inhibited LPS-induced production of prostaglandin E2 (PGE2) and nitric oxide (NO) through the down-regulation of expression of COX-2 and iNOS, respectively. OMC also inhibited LPS-dependent DNA-binding activity of AP-1 and NF-κB in RAW264.7 cells. Oral administration of OMC markedly suppressed secretion of TNF-α and IL-6 in mice challenged with LPS in vivo. Anti-inflammatory activity of OMC was confirmed by the inhibition of proliferation and secretion of interferon-γ (IFN-γ), IL-2, and IL-6 from concanavalin A (ConA)-stimulated mouse splenocytes.ConclusionsOur study suggests that oyster mushroom possesses anti-inflammatory activities and could be considered a dietary agent against inflammation. The health benefits of the oyster mushroom warrant further clinical studies.

Nutritional contents of three edible oyster mushrooms grown on two substrates at Haramaya, Ethiopia, and sensory properties of boiled mushroom and mushroom sauce

SummaryThe effects of wheat and bean straw growing substrates on nutrient contents of three edible oyster mushrooms and sensory properties of two mushroom foods were investigated. Moisture (fresh weight basis), crude protein, fat, fibre, ash, total carbohydrate, Fe, P and Zn (db) were ranged: 85.18–88.86%, 30.04–37.63%, 1.61–2.55%, 9.33–13.29%, 6.83–9.38%, 29.68–32.53%, 4.86–5.66 mg per 100 g, 12.39–15.36 g kg−1 and 54.61–65.98 mg kg−1, respectively. Moisture, fat and fibre were significantly (P < 0.01) affected by substrates, species and their interactions. Substrates showed no differences on ash, Fe and P (P > 0.05). Protein content was high for mushrooms grown on bean straw. Pleurotus sajor‐caju grown on bean straw had high protein, ash, Fe and P contents. No significant (P > 0.05) sensory acceptability differences were observed for boiled mushroom and mushroom sauce except colour of boiled mushrooms. In Ethiopia, if mushroom consumption is popularised, the support for food nutrition security is substantial.

Photo-Irradiated Biosynthesis of Silver Nanoparticles Using Edible MushroomPleurotus floridaand Their Antibacterial Activity Studies

This is a report on photo-irradiated extracellular synthesis of silver nanoparticles using the aqueous extract of edible oyster mushroom (Pleurotus florida) as a reducing agent. The appearance, size, and shape of the silver nanoparticles are understood by UV-visible spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. The X-ray diffraction studies, energy dispersive X-ray analysis indicate that particles are crystalline in nature. Fourier transform infrared spectroscopy analysis revealed that the nanoparticles are covered with biomoieties on their surface. As can be seen from our studies, the biofunctionalized silver nanoparticles thus produced have shown admirable antimicrobial effects, and the synthetic procedure involved is eco-friendly and simple, and hence high range production of the same can be considered for using them in many pharmaceutical applications.

EPR and FTIR studies reveal the importance of highly ordered sterol-enriched membrane domains for ostreolysin activity

Ostreolysin is a cytolytic protein from the edible oyster mushroom (Pleurotus ostreatus), which recognizes specifically and binds to raft-like sterol-enriched membrane domains that exist in the liquid-ordered phase. Its binding can be abolished by micromolar concentrations of lysophospholipids and fatty acids. The membrane activity of ostreolysin, however, does not completely correlate with the ability of a certain sterol to induce the formation of a liquid-ordered phase, suggesting that the protein requires an additional structural organization of the membrane to exert its activity. The aim of this study was to further characterize the lipid membranes that facilitate ostreolysin binding by analyzing their lipid phase domain structure. Fourier-transformed infrared spectroscopy (FTIR) and electron paramagnetic resonance (EPR) were used to analyze the ordering and dynamics of membrane lipids and the membrane domain structure of a series of unilamellar liposomes prepared by systematically changing the lipid components and their ratios. Our results corroborate the earlier conclusion that the average membrane fluidity of ostreolysin-susceptible liposomes alone cannot account for the membrane activity of the protein. Combined with previous data computer-aided interpretation of EPR spectra strongly suggests that chemical properties of membrane constituents, their specific distribution, and physical characteristics of membrane nanodomains, resulting from the presence of sterol and sphingomyelin (or a highly ordered phospholipid, dipalmitoylphosphatidylcholine), are essential prerequisites for ostreolysin membrane binding and pore-formation.

Effect of Pleurotus ostreatus fermentation on cocoa pod husk composition: Influence of fermentation period and Mn2+ supplementation on the fermentation process.

Cocoa pod husk (CPH) is a major agro-industrial residue in Ghana with a potential value as a low-cost unconventional feedstuff for livestock. However, its effective use is limited by poor nutrient composition, mainly due to its high lignocellulose or fibre and also low protein levels. White–rot fungi such as Pleurotus species are bio-catalytic systems for bioconversion processes such as the bioconversion of lignocellulose materials into value-added products including nutritious animal feed. Presence of metals such as manganese (II) ions is reported to enhance fungal enzyme activity in the bioconversion of industrial lignocellulosic residues. The current study investigated the viability of using and optimising a fermentation process involving edible oyster mushroom (Pleurotus ostreatus) as biocatalyst to improve the nutritional status of CPH. Fermentation period and level of manganese (Mn2+) ion supplementation of CPH were the two major factors of the fermentation process evaluated and optimised in this study. Mn supplementation was critical in producing a positive bioconversion effect on CPH by P. ostreatus. Five (5) weeks of P. ostreatus solid-state fermentation of CPH amended with MnCl2 at 0.075% (w/w) concentration, was observed as an economic and optimum treatment to produce positive and significant (P < 0.05) changes in CPH composition, i.e. 36% increment in crude protein and total soluble carbohydrates; 17% reduction in crude fibre and lignin as well as 88% reduction in total tannins.

Assessment of Selected Antioxidants in Tomato Pomace Subsequent to Treatment with the Edible Oyster Mushroom, Pleurotus ostreatus, under Solid-State Fermentation

Tomato pomace, delignified by the edible oyster mushroom, Pleurotus ostreatus, could be used as a poultry feed ingredient to provide alpha-tocopherol for retardation of lipid oxidation in postmortem meat if the antioxidant were retained in pomace after fungal fermentation. Experiments were conducted to investigate changes in the content of alpha-tocopherol, lycopene, and beta-carotene in tomato pomace after sterilization and treatment with P. ostreatus from 0 to 104 days. alpha-Tocopherol (39.26 to 31.15 microg/g) and lycopene (17.42 to 11.19 microg/g) significantly decreased during sterilization while beta-carotene (42.56 to 35.44 microg/g) did not. The content of carotenoids decreased by day 26 as compared to 0 day for the control and for treated samples. alpha-Tocopherol decreased during fungal fermentation at day 26 as compared to 0 day for the control and increased during the same period for treated samples. By 104 days, only alpha-tocopherol in control pomace was present in a significant amount. The alpha-tocopherol content of mushroom fruit grown in pomace (74.10 microg/g) and in wheat straw (51.36 microg/g) was not significantly different. Tomato pomace could be used as a substrate to successfully grow edible mushrooms; however, the initial level of selected antioxidants and their reduction during fungal fermentation must be considered when delignified pomace is utilized for selected nutrient content in animal feed or products for human consumption.

Ostreolysin affects rat aorta ring tension and endothelial cell viability in vitro

The effects of ostreolysin, a cardiotoxic cytolysin produced by the edible oyster mushroom ( Pleurotus ostreatus), were studied on tension development in isolated rat aortic ring. Its cytotoxic effects on human umbilical vein endothelial cells and Chinese hamster lung fibroblasts were also studied. Ostreolysin induced a concentration-dependent increase in aortic ring tension in the range from 5 to 30 μg/ml, and was cytotoxic to both cell lines. These effects could contribute significantly to its previously observed cardiotoxicity.

Toxic and lethal effects of ostreolysin, a cytolytic protein from edible oyster mushroom ( Pleurotus ostreatus), in rodents

Ostreolysin (Oly), an acidic, 15 kDa protein from the edible oyster mushroom ( Pleurotus ostreatus), is a toxic, pore-forming cytolysin. In this paper, its toxic properties have been studied in rodents and the LD 50 in mice shown to be 1170 μg/kg. Electrocardiogram, arterial blood pressure and respiratory activity were recorded under general anaesthesia, in intact, pharmacologically vagotomised and artificially respirated rats injected with one mouse LD 50. A few seconds after intravenous Oly injection, a transient increase in arterial blood pressure was recorded, followed by a progressive fall to mid-circulatory pressure accompanied by bradicardia, myocardial ischaemia and ventricular extrasystoles. Similar changes produced by Oly were observed in vagotomised and artificially respirated animals, indicating that vagotomy and hypoxia play no primary role in toxicity. Oly induced lysis of rat erythrocytes in vitro, and probably also in vivo as indicated by the increase in serum potassium. Although direct action of the protein on the cardiomyocytes or heart circulation cannot be excluded, the hyperkalaemia resulting from the haemolytic activity probably plays an important role in its toxicity. The lethality and cardiorespiratory toxic action of Oly are thus shown to be candidates for the cause of the recorded adverse effects of oyster mushroom.

Steroid structural requirements for interaction of ostreolysin, a lipid-raft binding cytolysin, with lipid monolayers and bilayers

Ostreolysin, a cytolytic protein from the edible oyster mushroom ( Pleurotus ostreatus), recognizes and binds specifically to membrane domains enriched in cholesterol and sphingomyelin (or saturated phosphatidylcholine). These events, leading to permeabilization of the membrane, suggest that a cholesterol-rich liquid-ordered membrane phase, which is characteristic of lipid rafts, could be its possible binding site. In this work, we present effects of ostreolysin on membranes containing various steroids. Binding and membrane permeabilizing activity of ostreolysin was studied using lipid mono- and bilayers composed of sphingomyelin combined, in a 1/1 molar ratio, with natural and synthetic steroids (cholesterol, ergosterol, β-sitosterol, stigmasterol, lanosterol, 7-dehydrocholesterol, cholesteryl acetate, and 5-cholesten-3-one). Binding to membranes and lytic activity of the protein are both shown to be dependent on the intact sterol 3β-OH group, and are decreased by introducing additional double bonds and methylation of the steroid skeleton or C17-isooctyl chain. The activity of ostreolysin mainly correlates with the ability of the steroids to promote formation of liquid-ordered membrane domains, and is the highest with cholesterol-containing membranes. Furthermore, increasing the cholesterol concentration enhanced ostreolysin binding in a highly cooperative manner, suggesting that the membrane lateral distribution and accessibility of the sterols are crucial for the activity of this new member of cholesterol-dependent cytolysins.

Effect of pH on the Pore Forming Activity and Conformational Stability of Ostreolysin, a Lipid Raft-Binding Protein from the Edible MushroomPleurotus ostreatus,

Ostreolysin, a pore-forming protein from the edible oyster mushroom (Pleurotus ostreatus), is a member of the aegerolysin protein family, a novel group of small acidic proteins found in bacteria, molds, mushrooms, and plants. It binds to lipid rafts and interacts specifically with cholesterol-rich lipid domains. In this study, ostreolysin was classified as a single-domain all-beta-structured protein on the basis of cDNA sequencing. pH-induced and thermally induced unfolding of ostreolysin was studied by means of CD, UV absorption, and intrinsic tryptophan fluorescence to characterize conformational transitions associated with its functional properties, i.e., binding to lipid membranes, pore forming activity on lipid vesicles, and hemolysis. At 25 degrees C and between pH 6 and 9, ostreolysin adopted a monomeric and thermodynamically stable nativelike conformation, characterized by rigid tertiary structure and predominantly beta-sheet secondary structure. Between pH 2 and 3, the protein underwent an irreversible transition to a partially unfolded, molten globule-like state which bound ANS, and exhibited disrupted tertiary structure and enhanced non-native alpha-helical structure. Functional studies showed that, unlike colicins and some other bacterial pore-forming toxins, the acid-induced molten globule-like state of ostreolysin is not relevant for lipid binding and pore formation. Instead, the compact native state was necessary for binding to cholesterol/sphingomyelin multilamellar vesicles, optimally in the pH range from 6 to 7, and for pore formation and hemolysis, maximally between pH 7 and 8.

Ostreolysin, a pore-forming protein from the oyster mushroom, interacts specifically with membrane cholesterol-rich lipid domains

Ostreolysin, a 15 kDa pore-forming protein from the edible oyster mushroom ( Pleurotus ostreatus), is lytic to membranes containing both cholesterol and sphingomyelin. Its cytotoxicity to Chinese hamster ovary cells correlates with their cholesterol contents and with the occurrence of ostreolysin in the cells detergent resistant membranes. Moreover, ostreolysin binds to supported monolayers and efficiently permeabilizes sonicated lipid vesicles, only if cholesterol is combined with either sphingomyelin or dipalmitoylphosphatidylcholine. Addition of mono- or di-unsaturated phosphatidylcholine to the cholesterol/sphingomyelin vesicles dramatically reduces the ostreolysin's activity. It appears that the protein recognizes specifically a cholesterol-rich lipid phase, probably the liquid-ordered phase.

Use of Edible and Medicinal Oyster Mushroom [Pleurotus ostreatus (Jacq.: Fr.) Kumm.] Spent Compost in Remediation of Chemically Polluted Soils

Use of Edible and Medicinal Oyster Mushroom [Pleurotus ostreatus (Jacq.: Fr.) Kumm.] Spent Compost in Remediation of Chemically Polluted Soils

An inexpensive pretreatment of cellulosic materials for growing edible oyster mushrooms

Artificial cultivation of oyster mushrooms on lignocellulosic materials involves the pretreatment of the substrate with hot water to ward off the competing molds during the spawn run. An inexpensive anaerobic pretreatment of the cellulosic materials has been suggested as an alternative to the conventional hot-water treatment.

Pleurotus ostreatus inhibits proliferation of human breast and colon cancer cells through p53-dependent as well as p53-independent pathway

In spite of the global consumption of mushrooms, only two epidemiological studies demonstrated an inverse correlation between mushroom intake and the risk of cancer. Therefore, in the present study we evaluated whether extracts from edible mushrooms Agaricus bisporus (portabella), Flammulina velutipes (enoki), Lentinula edodes (shiitake) and Pleurotus ostreatus (oyster) affect the growth of breast and colon cancer cells. Here, we identified as the most potent, P. ostreatus (oyster mushroom) which suppressed proliferation of breast cancer (MCF-7, MDA-MB-231) and colon cancer (HT-29, HCT-116) cells, without affecting proliferation of epithelial mammary MCF-10A and normal colon FHC cells. Flow cytometry revealed that the inhibition of cell proliferation by P. ostreatus was associated with the cell cycle arrest at G0/G1 phase in MCF-7 and HT-29 cells. Moreover, P. ostreatus induced the expression of the tumor suppressor p53 and cyclin-dependent kinase inhibitor p21(CIP1/WAF1), whereas inhibited the phosphorylation of retinoblastoma Rb protein in MCF-7 cells. In addition, P. ostreatus also up-regulated expression of p21 and inhibited Rb phosphorylation in HT-29 cells, suggesting that that P. ostreatus suppresses the proliferation of breast and colon cancer cells via p53-dependent as well as p53-independent pathway. In conclusion, our results indicated that the edible oyster mushroom has potential therapeutic/preventive effects on breast and colon cancer.

The Pleurotus ostreatus-sapidus Species Complex

SUMMARYTwo macroscopically indistinguishable, noninterbreeding populations of edible oyster mushrooms were studied. These were determined to be Pleurotos ostreatus which was found only on Populus tremuloides and had a cream-colored spore print, slightly larger basidiospores, and a growth rate on nutrient agar about half that of the other population, P. sapidus. The latter species had a lilac spore print and a wide host range of angiosperm trees.

The Pleurotus Ostreatus-Sapidus Species Complex

SUMMARYTwo macroscopically indistinguishable, noninterbreeding populations of edible oyster mushrooms were studied. These were determined to be Pleurotos ostreatus which was found only on Populus t...