Characterization and in vitro antioxidant activities of polysaccharides from Pleurotus ostreatus

Two polysaccharide fractions (PSPO-1a and PSPO-4a) were isolated from the fruiting bodies of Pleurotus ostreatus using ethanol precipitation, anion-exchange chromatography and gel permeation chromatography. Both fractions were heteropolysaccharide containing protein and uronic acid. PSPO-1a was composed of mannose, glucose, galactose, xylose and rhamnose with a molar ratio of 2.47:0.91:1.00:1.66:3.87. PSPO-4a was composed of only three monosaccharides: rhamnose, mannose and galactose with a molar ratio of 0.92:2.69:1.00. The average molecular weight of PSPO-1a and PSPO-4a determined by HPLC were estimated to be 1.8 × 10(4)Da and 1.1 × 10(6)Da respectively. The in vitro tests revealed that two polysaccharides were natural potential antioxidant. Both polysaccharides presented stronger DPPH radical and superoxide anion radical scavenging activity with increasing concentrations, but less effective on scavenging hydroxyl radical. Compared with PSPO-4a, PSPO-1a was the more effective free-radical scavenger. In conclusion, the two polysaccharides may be useful as a naturally potential antioxidant agent for application in food and medicinal fields.     

平菇菌粗多糖的抗氧化活性研究

采用深层发酵技术生产平菇粗多糖,时其清除DPPH自由基、羟自由基的能力、铁离子螯合能力以及还原力进行了比较分析。结果表明：菌丝体粗多糖和发酵液粗多糖均具有较强的抗氧化能力,但2种多糖的抗氧化能力存在差异;茵丝体粗多糖清除DPPH自由基的能力较强,其EC。。值为2．20mg／mL;发酵液粗多糖清除羟自由基的能力、铁离子螯合能力以及还原力较强,其EC50值分别为0．72mg／mL、3．32mg／mL和7．91mg／mL。在一定的浓度范围内,多糖的浓度增加,其抗氧化能力也随之增强,呈量效依赖关系。     

Whey permeate as a growth medium for Pleurotus ostreatus and Lentinus edodes

Whey permeate, a dairy by-product, was studied as a growth medium for two white-rot Basidiomycetes, Lentinus edodes and Pleurotus ostreatus. Mycelial growth and phenoloxidase production appeared to be highly stimulated when the fungi were grown on the permeate instead of synthetic medium. No further increment in phenoloxidase production was observed when the permeate was supplemented with CuSO₄.     

Production of biomass and ligninolytic enzymes by Pleurotus ostreatus in submerged culture.

The production of biomass and ligninolytic enzymes by Pleurotus ostreatus was analysed in synthetic medium with yeast extract and different glucose concentrations (0.5 - 20 g/l), at different pH (3.5-6.5) and incubation temperatures (23-32 degrees C). The best culture condition were: initial glucose concentration of 5 g/l, initial pH between 5.5-6.5 and incubation temperature between 26-29 degrees C. The saturation constant for glucose (Ks) was 1.75 g/l. The biomass concentration reached 8.6 g/l with a glucose addition of 20.0 g/l to the culture medium. The control of pH allowed an increment of 0.5 g/l of biomass concentration. The birreactor produced pellets with a homogeneous distribution of diameter size of 3.4 -/+ 0.2 mm. Approximately, 307 U/l of laccase and 0.41 U/l of manganese peroxidase were obtained in extracellular liquid medium and 0.015 U/g of laccase and 0.809 U/g of manganese peroxidase were obtained in solid substrate. Lignin peroxidase activity was not detected at any condition.     

The use of spent brewery grains for Pleurotus ostreatus cultivation and enzyme production

In the brewing industry, spent brewery grains (SBGs) are byproducts with a low economic value. The potential use of this leftover as a substrate ingredient for Pleurotus ostreatus fruiting body cultivation and enzyme production was evaluated. The best substrate mixture for P. ostreatus mycelium growth comprised 30% wheat bran (WB), 68% beech sawdust (BS) and 2% CaCO3. On the substrates containing SBG, the fastest mycelium growth was observed on the substrate composed of 10% SBG, 20% WB, 68% BS and 2% CaCO3. The highest biological efficiency (51%) of fruiting bodies was determined on the mixtures containing 20% WB, 10% SBG and 2% CaCO3. The SBGs with the addition of WB were also shown to be suitable as a substrate for enzyme production. However, the supplementation levels designate which enzymes are produced and in what amounts.     

一种快速辨别糙皮侧耳和肺形侧耳的方法

目的：建立一种快速、经济的方法辨别糙皮侧耳（P.ostreatus）和肺形侧耳（P.pulmonarius）。方法：在GenBank下载糙皮侧耳和肺形侧耳的ITS序列,经ClustalX序列比对,利用Primer 3设计特异引物组合1F（5′-GATAGATCTGTGAAGTCGTC-3′）、1R（5′-TCACAATTGGAAAGAAACC-3′）和2R（5′-TGCGTGCTATTGATGAGTGA-3′）,最后经PCR扩增和琼脂糖凝胶电泳检测。结果：5个糙皮侧耳菌株均能得到2条带,分别为342bp和459bp。4个肺形侧耳菌株均能扩增到一条446bp的片段。结论：该组引物适合辨别糙皮侧耳和肺形侧耳。     

Growth and laccase production by Pleurotus ostreatus in submerged and solid-state fermentation

Pleurotus ostreatus showed atypical laccase production in submerged vs. solid-state fermentation. Cultures grown in submerged fermentation produced laccase at 13,000 U l⁻¹, with a biomass production of 5.6 g l⁻¹ and four laccase isoforms. However, cultures grown in solid-state fermentation had a much lower laccase activity of 2,430 U l⁻¹, biomass production of 4.5 g l⁻¹, and three laccase isoforms. These results show that P. ostreatus performs much better in submerged fermentation than in solid-state fermentation. This is the first report that shows such atypical behavior in the production of extracellular laccases by fungi.     

Classical breeding in Pleurotus ostreatus: a natural approach for laccase production improvement

White-rot basidiomycetes, the most common wood-rotting organisms, are characterized by their ability to produce extracellular oxidative enzymes, among which laccases are regarded as promising catalysts for many biotechnological applications. A significant obstacle to the exploitation of laccase-based bioprocesses is the large amounts of enzyme required. In this study the issue has been addressed by applying a classical breeding approach to increase laccase production yields in the white-rot fungus Pleurotus ostreatus. Starting from two different P. ostreatus varieties, three higher laccase-producing hybrids have been obtained by crossing selected compatible monokaryons. The three selected strains increased the titre of parental strains up to four fold, reaching an expression level of up to 100 000 U/L. One hybrid exhibited a more complex isoenzyme pattern, illustrating the potential of classical breeding to differentiate protein expression.     

Improved conditions for protoplast formation and transformation of Pleurotus ostreatus

Conditions suitable for the production and regeneration of Pleurotus ostreatus protoplasts from dikaryotic mycelia were examined. Three commercially available muralytic enzymes, including Sigma lysing enzyme, Novozym 234 and Novozym 234 LP, were used for production of protoplasts. Over 2 × 10⁷ protoplasts per gram fresh weight mycelia were obtained within 1.5 h by using each of these three enzymes. The colony regeneration rate was up to 13% on potato-dextrose-agar medium containing 0.8 m mannitol. Genetic transformation was based on positive selection for resistance to hygromycin B (HmB) using the plasmid vector pAN7-1 and accomplished by either electroporation or a polyethylene glycol (PEG)-divalent cation method. P. ostreatus strains used in this study have innate sensitivity to HmB at a critical inhibitory concentration of between 40–50 g/ml. Selection for HmB resistance of this fungus, indicative of transformation, resulted in 3–48 HmB-resistant colonies per microgram of pAN7-1 per 10⁷ viable protoplasts. No significant differences were apparent when either transformation protocol or either P. ostreatus strain was used. The best electrical condition found for the electrotransformation of P. ostreatus is at a field strength of 2.6–2.8 kV/cm with a capacitance of 25F and a parallel resistance of 800 ohms, corresponding to a time constant range of 10–14 ms. Correspondence to: P. A. Lemke     

Optimization of production conditions for mushroom polysaccharides with high yield and antitumor activity

Single factor experiment and response surface methodology were conducted to optimize the production conditions for polysaccharide with higher antitumor activity from mushroom fermentation broth. Based on the results of single factor experiments, a central composite design was applied to the following optimization and second-order polynomial regression models were established. As the yield and antitumor activity of the polysaccharides were considered with equal weight, the optimal conditions were that ethanol concentration and pH of the broth was adjusted to 85.00% and 7.70 respectively, then precipitated at 12 °C for 1 h and dried the precipitates at 40 °C. The verification experiments completed under the optimal conditions gave the polysaccharides yield of 9.843 ± 0.217 g/l, and the cancer cell growth inhibitory rate of 83.69 ± 0.167% by the polysaccharides, which were in close agreement with values predicted by the models (RSD < 5%).     

全基因组预测糙皮侧耳经典胞外分泌蛋白

糙皮侧耳(平菇)作为目前木质纤维素降解模式真菌,其产生的胞外分泌蛋白在植物纤维素、半纤维素及木质素降解过程中发挥着重要作用。为了给蛋白质组学鉴定糙皮侧耳胞外分泌蛋白实验提供参考,利用常见的生物信息学工具SignalP、ProtComp、TMHMM、big-PI Fungal Predictor和TargetP对糙皮侧耳全基因组中的12 186条蛋白质序列进行经典分泌蛋白预测,同时,对上述分泌蛋白的氨基酸分布、信号肽长度和切割位点以及其理化性质等进行分析。结果表明,糙皮侧耳全基因组中含有359个经典分泌蛋白,其氨基酸长度主要集中于101~600之间;信号肽长度集中在18~21之间;信号肽切割位点属于A-X-A类型,除此之外还含有5条具有RR-motif的信号肽。对这些分泌蛋白进行功能注释,结果表明225个蛋白质为未知功能蛋白质;114个为已知功能蛋白质,主要功能注释集中于木质纤维素降解酶类,包括纤维素酶、半纤维素酶、木质素降解相关酶等。以上结果表明通过上述生物信息学分析实现了对糙皮侧耳全基因组经典分泌蛋白的有效预测。     

Whey as a medium for biomass production ofSulfolobus solfataricus

Summary The use of whey, a liquid by-product of dairy industry without any pre-treatment as growth medium for the thermophilic archaeonSulfolobus solfataricus, is reported.     

Decolourization of Municipal Effluent and Sludge by Pleurotus sajor-caju and Pleurotus ostreatus

Summary The Americana Municipal Treatment Station, S?o Paulo, Brazil, manages 400 l of effluent s⁻¹, from domestic and textile origin, which produces an average of 20 t of sludge per day. The decolourization of the effluent and sludge by three strains of Pleurotus (Pleurotus sajor-caju F2, F6 and Pleurotus ostreatus) was evaluated. The strains of P. sajor-caju F2 and F6 were able to decolourize the sludge, while P. ostreatus was less efficient. Detoxification was appraised with three bioassays comprising the cnidarian Hydra attenuata, the alga Selenastrum capricornutum and lettuce seeds. After exposure to fungi, effluent toxicity decreased but not that of its sludge. Strain P. sajor-caju F6 presented signs of toxicity shown by electron microscopy in the presence of the effluent. The three strains produced high amounts of manganese-peroxidase (Mn–P) and laccase in the presence of the sludge. Although P. ostreatus produced large amount of Mn–P and laccase enzymes, these enzymes did not result in decolourization of the sludge, suggesting that other factors are likely to be involved. Carbon content decreased only in the treatment with P. ostreatus.     

Use of coffee grounds for production of Pleurotus ostreatus (Jacq.:Fr.) Kummer

Studies were carried out to screen the industrial strain HK35 of Pleurotus ostreatus for its ability to develop fruiting bodies in solid state cultivation using several substrates containing 17.8 to 55% coffee grounds. Our results showed that only 55% of coffee grounds was used in the substrate without detecting changes in fruiting body or on its biological efficiency of production. The chemical analysis of the caffeine in the substrate showed that this compound decreased about 59% of the mycelium activity, and no caffeine was found in fruiting bodies indicating its degradation by the fungal strain tested.     

Waste-reducing cultivation of Pleurotus ostreatus and Pleurotus pulmonarius on coffee pulp: changes in the production of some lignocellulolytic enzymes

Fruiting body production for one strain of Pleurotus ostreatus and three strains of P. pulmonarius was evaluated on coffee pulp pasteurized at 80 °C for 1 h. Based upon three harvests per strain, the single P. ostreatus line was found to display a 40-day culture cycle, whereas the three P. pulmonarius strains completed their cycles after more than 50 days of incubation. These time periods were notably shorter than those observed in previous studies using other growth substrates. Nevertheless, yields expressed as biological efficiencies were not significantly different among strains, fluctuating between 125 and 138%. Extracellular enzymatic activity was also monitored for P. ostreatus and P. pulmonarius (one strain only). To do this, samples of mycelium-bearing substrate were taken every 4 days throughout the incubation period. Care was taken to represent all developmental stages, including primordial and fruiting bodies. Samples were either lyophilized and then analysed or, in some cases, analysed immediately without lyophilization. Hydrolase activity (i.e. endoglucanase (CMC) and cellobiohydrolase (CBH)) was found to depend on developmental stage, showing peak production during fruiting body formation. On the other hand, oxidase activity-(i.e. laccase (LAC) and Mn-peroxidase (MnP)) was associated with phenol degradation. Nevertheless, in the case of oxidases developmental timing differences were also observed. Specifically, LAC activity was detected as early as 8 days after inoculation in non-lyophilized samples, whereas MnP appeared near the end of the incubation period. No LAC activity was observed in lyophilized samples. This study concludes that coffee pulp might be successfully employed in the cultivation of mushrooms, not only because important extracellular enzymes are produced by mushrooms when grown upon this substrate, but also because the abbreviated cultivation cycle associated with this medium favours commercial processes. Commercialization might be further improved if strains specifically adapted to this novel substrate are selected.     

Growth characteristics of Pleurotus ostreatus in bioreactors

Pleurotus ostreatus was cultured in a bioreactor equipped with different impeller geometries under non-limiting nutrient conditions. With a Rushton turbine impeller the specific growth rate decreased 30% and pellet diameter was reduced 15% when the aeration rate was increased from 1 to 1.5 vvm. Agitation rate reduced the pellet diameter from 5.1 mm to 2.8 mm using 200 rpm and 400 rpm of agitation, respectively. Specific growth rates of 0.036, 0.020 and 0.041 h–1 were obtained with Roshton (disc turbine), Helical Ribbon and InterMIG impellers, respectively. Impeller geometry is important to control the pellet size and consequently growth rate of P. ostreatus.     

Cultivation of Pleurotus ostreatus on weed plants

Oyster mushroom, Pleurotus ostreatus (Jacq.:Fr.) Kumm. ITCC 3308 (collected from Indian Type Culture Collection, IARI, New Delhi, India, 110012) was grown on dry weed plants, Leonotis sp, Sida acuta, Parthenium argentatum, Ageratum conyzoides, Cassia sophera, Tephrosia purpurea and Lantana camara. Leonotis sp. was the best substrate in fruit body production of P. ostreatus when it was mixed with rice straw (1:1, wet wt/wet wt) for mushroom cultivation. The fruiting time for P. ostreatus was also less on Leonotis sp. than on any other weed substrates tested in the present investigation. T. purpurea was the least suited weed for oyster mushroom cultivation. The main problem of oyster mushroom cultivation on weed substrates was found to be low yield in the second flush that could be overcome by blending weed plants with rice straw. The protein contents of the fruit bodies obtained from Cassia sophera, Parthenium argentatum and Leonotis sp. were not only better than rice straw but also from the rice straw supplemented weeds.     

Effect of culture medium composition on peroxidase biosynthesis by the fungus Pleurotus ostreatus UzBI-I105

Production of extracellular peroxidase during submerged cultivation of the xylotrophic bazidiomycete Pleurotus ostreatus UZBI-I105 in nutrient media with lignocellulosic wastes, exhausted cottonseed oil cake, cotton stalks, rice husks, or ambary hemp was studied. The enzyme production increased threefold to fivefold in the presence of exhausted cottonseed oil cake extract in the nutrient medium. The dynamics of peroxidase production in various media was investigated.     

Cultivation of Pleurotus ostreatus and other edible mushrooms

Pleurotus ostreatus is the second most cultivated edible mushroom worldwide after Agaricus bisporus. It has economic and ecological values and medicinal properties. Mushroom culture has moved toward diversification with the production of other mushrooms. Edible mushrooms are able to colonize and degrade a large variety of lignocellulosic substrates and other wastes which are produced primarily through the activities of the agricultural, forest, and food-processing industries. Particularly, P. ostreatus requires a shorter growth time in comparison to other edible mushrooms. The substrate used for their cultivation does not require sterilization, only pasteurization, which is less expensive. Growing oyster mushrooms convert a high percentage of the substrate to fruiting bodies, increasing profitability. P. ostreatus demands few environmental controls, and their fruiting bodies are not often attacked by diseases and pests, and they can be cultivated in a simple and cheap way. All this makes P. ostreatus cultivation an excellent alternative for production of mushrooms when compared to other mushrooms.