Solid state fermentation of plant residues for improved animal feed byPleurotus sp.

In laboratory-scale experiments, studies were made on the solid state fermentation of plant residues—rice straw and the upper soft portion of the stems of sarkanda (Saccharum munja)—by selected cultures of white-rot fungi,Pleurotus sajor-caju andPleurotus ostreatus. These cultures were selected after preliminary screening of their lignin-degrading capacities on lignin-agar medium. Their lignin degrading and (cellulose + hemicellulose) sparing, along with protein improving capacities, were studied for their potential application in animal feed production. A 100 g quantity of presoaked and sterilized residues was inoculated with wheat spawn of the two cultures and incubated at 25‡C. It was observed that, after 25 d, the crude protein contents (N × 6.25) of rice straw increased from 3 to 17.0% in the case of P.sajor-caju and to 19.2% in case of P. ostreatus. The percent removal values of cellulose, hemicellulose, and lignin were found to be as follows: 45.8, 16.8, and 47.1%, respectively, in the case ofP. sajor-caju and 56.5, 40.4, and 50%, respectively, in the case of P.ostreatus. After solid state fermentation of sarkanda for 25 d, its protein content increased from 3 to 12.8% in the case ofP. sajor-caju and to 14.5% in the case ofP. ostreatus. The percent removal of cellulose, hemicellulose, and lignin was found to be as follows: 31.2, 7.1, and 19%, respectively, in the case ofP. sajor-caju and 34.4, 7.1, and 14.3%, respectively, in the case ofP. ostreatus. The results obtained after solid state fermentation of the two residues by the mixed culture of these two basidiomycetes was also presented.     

Lignocellulolytic mutants of Pleurotus ostreatus induced by gamma-ray radiation and their genetic similarities

To induce the lignocellulolytic mutants of Pleurotus ostreatus, the mycelia were irradiated by gamma-ray radiation to doses of 1–2 kGy. Five strains were isolated by the criteria of clamp connection, fruiting body formation, growth rate and activities of extracellular enzymes. All isolated strains were able to form the fruiting bodies and grew similarly to the control. The extracellular enzymes activities in liquid media of isolated strains were up to 10 times higher than the control. Genetic similarities of the isolated strains ranged from 64.4% to 93.3% of the control. From these results, it seems that the genetic diversity of P. ostreatus could be changed and useful strains be induced by gamma-ray radiation to recycle or reuse biowastes.     

Production of ligninolytic enzymes for dye decolorization by cocultivation of white-rot fungi Pleurotus ostreatus and Phanerochaete chrysosporium under solid-state fermentation

Lignocellulosic wastes such as neem hull, wheat bran, and sugarcane bagasse, available in abundance, are excellent substrates for the production of ligninolytic enzymes under solid-state fermentation by white-rot fungi. A ligninolytic enzyme system with high activity showing enhanced decomposition was obtained by cocultivation of Pleurotus ostreatus and Phanerochaete chrysosporium on combinations of lignocellulosic waste. Among the various substrate combinations examined, neem hull and wheat bran wastes gave the highest ligninolytic activity. A maximum production of laccase of 772 U/g and manganese peroxidase of 982 U/g was obtained on d 20 and lignin peroxidase of 656 U/g on d 25 at 28±1 °C under solid-state fermentation. All three enzymes thus obtained were partially purified by acetone fractionation and were exploited for decolorizing different types of acid and reactive dyes.     

Bioconversion of different agro-residues into edible protein byPleurotus sajor-caju

Pleurotus sajor-caju, an edible mushroom, is a source of protein-rich food.Pleurotus sajor-caju has broad temperature (15–25‡C) and pH (4-6) optima for its growth, thus making it suitable for village-level applications, where it can be cultivated in a generally artificially uncontrolled environment. In the present investigations, the following agro-residues have been used for cultivation of this mushroom: paddy straw, wheat straw, bagasse,Cyamposis tetragonoloba, Sorghum vulgare, Pennesitum typhoideum, mango leaves, banana leaves,Zea mays, etc. and some residues mixed with other materials such as cotton seeds, fiscus fruits,Azadirachta indica leaves, etc. All the substrates (400 g) were pasteurized at 60‡C, soaked in water, packed in polythene bags, and inoculated with 8% wheat spawn on a dry weight basis. The cultivation was carried out for 2 months, during which four crops were harvested. The temperature was 10–25‡C and relative humidity was maintained at 80–90%. The maximum yields in percent of fruit bodies obtained were as follows: banana leaves, 125 (91.8), paddy straw, 124.2 (90.6), wheat straw, 111.7 (90),Sorghum vulgare, 108.8 (92.9),Cyamposis tetragonoloba, 108.3 (91.5), followed by others. The maximum yields in percent of fruit bodies obtained in combinations of some substrates were as follows: paddy straw + cotton seeds, 148.3 (91.3),Cyamopsis tetragonoloba + Azadirachta indica leaves, 105.8 (91.5),Sorghum vulgare + Azadirachta indica leaves, 103.8 (91.8); the figures in parentheses represent the percent moisture content. The biochemical changes effected as a result of mushroom growth in terms of utilization of cellulose, hemicellulose, and lignin were presented.     

Induction and Purification by Three-Phase Partitioning of Aryl Alcohol Oxidase (AAO) from <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis>

Aryl alcohol oxidase (AAO) is an extracellular flavoenzyme involved in lignin degradation by white rot fungi. Screening of lignolytic and AAO activity from twenty different fungal species were carried out. Among them, seven species showed lignolytic activity and three of them (Pleurotus ostreatus, Pleurotus eous, and Pleurotus platypus) were found to be AAO positive. Maximal AAO activity was observed in batch cultures of P. ostreatus and was found to be induced by aromatic amino acids and aryl alcohols up to a level of 289 U/l. Purification of AAO was carried out by three-phase partitioning (TPP). The 67 kDa enzyme was purified up to 10.19-fold by TPP with an overall recovery of 10.95%. Optimum pH and temperature for P. ostreatus AAO activity was found to be around 6 and 40 °C, respectively. From the LB plot, K _m value of AAO for oxidizing veratryl alcohol was determined to be 0.6 mM. Results of the study indicate that P. ostreatus is the best producers of AAO, and they could be employed as promising fungal species for biotechnological applications.     

Proteome Analysis and In Vitro Antiviral,Anticancer and Antioxidant Capacities of the Aqueous Extracts of Lentinula edodes and Pleurotus ostreatus Edible Mushrooms

In this study, we examined aqueous extracts of the edible mushrooms Pleurotus ostreatus (oyster mushroom) and Lentinula edodes (shiitake mushroom). Proteome analysis was conducted using LC-Triple TOF-MS and showed the expression of 753 proteins by Pleurotus ostreatus, and 432 proteins by Lentinula edodes. Bioactive peptides: Rab GDP dissociation inhibitor, superoxide dismutase, thioredoxin reductase, serine proteinase and lectin, were identified in both mushrooms. The extracts also included promising bioactive compounds including phenolics, flavonoids, vitamins and amino acids. The extracts showed promising antiviral activities, with a selectivity index (SI) of 4.5 for Pleurotus ostreatus against adenovirus (Ad7), and a slight activity for Lentinula edodes against herpes simplex-II (HSV-2). The extracts were not cytotoxic to normal human peripheral blood mononuclear cells (PBMCs). On the contrary, they showed moderate cytotoxicity against various cancer cell lines. Additionally, antioxidant activity was assessed using DPPH radical scavenging, ABTS radical cation scavenging and ORAC assays. The two extracts showed potential antioxidant activities, with the maximum activity seen for Pleurotus ostreatus (IC50 µg/mL) = 39.46 ± 1.27 for DPPH; 11.22 ± 1.81 for ABTS; and 21.40 ± 2.20 for ORAC assays. This study encourages the use of these mushrooms in medicine in the light of their low cytotoxicity on normal PBMCs vis à vis their antiviral, antitumor and antioxidant capabilities.     

Cellulolytic enzymes produced by the edible mushroom,Pleurotus sajor-caju

Pleurotus sajor-caju grows efficiently and degrades all the components present in lignocellulosic residues. Production of cellulase and xylanase enzymes in submerged culture and during solid state cultivation has been studied. An initial pH of 5.0 was found to be optimal for the production of cellulase in shake flasks; this was attained in about 6–8 d in a medium containing either cellulose or rice straw as the sole source of carbon. On the cellulose medium, the maximum filter paper activity attained was 0.15 IU/mL in 7 d whereas the endoglycanase activity of 1.0 IU/mL, xylanase activity of 1.55 IU/mL, and Β-glucosidase activity of 0.57 IU/mL were acheived after 9 d fermentation. The reducing sugars were absent in the culture medium. The cellulases (filter paper activity and endoglucanases) were most active at pH 5.0 and 45‡C. Xylanase had maximum activity at pH 4.8 and 45‡C, and Β-glucosidase at pH 5.5 and 40‡C. In shake cultures,P. sajor-caju produced dispersed suspension of short mycelial threads and various sizes of pellets. The profile and extent of enzyme biosynthesis during submerged cultivation on rice straw was found to be of the same nature as obtained on cellulose. During solid state cultivation ofP. sajor-caju on rice straw beds for 36 d, the elaboration of enzyme activities did not appear to follow any definite pattern. However, filter paper activity, which is representative of cellulase action in hydrolyzing cellulose, remained more or less constant during the period of about the first 20 d of cultivation after the appearance of fruit bodies on the surface of rice straw beds. All the activities attained their minimum values after 23 d of cultivation, during which approximately 1 kg of fresh fruit bodies had been harvested. The total fruit bodies harvested till 36th days were approx. 1.1 kg. ThroughT. sajor-caju elaborates cellulase and xylanse extracellularly, the activity values were not as high as those of other cellulase producers such asTrichoderma reesei.     

Fungal upgrading of wheat straw for straw-thermoplastics production

Combining biologic pretreatment with storage is an innovative approach for improving feedstock characteristics and cost, but the magnitude of responses of such systems to upsets is unknown. Unsterile wheat straw stems were upgraded for 12 wk with Pleurotus ostreatus at constant temperature to estimate the variation in final compositions with variations in initial moisture and inoculum. Degradation rates and conversions increased with both moisture and inoculum. A regression analysis indicated that system performance was quite stable with respect to inoculum and moisture content after 6 wk of treatment. Scale-up by 150× indicated that system stability and final straw composition are sensitive to inoculum source, history, and inoculation method. Comparative testing of straw-thermoplastic composites produced from upgraded stems is under way.     

Antimicrobial and Antineoplasic Activity of Pleurotus ostreatus

The objectives of this work were to evaluate the antimicrobial and antineoplasic activity of Pleurotus ostreatus DSM 1833. To study the antimicrobial activity, the following extracts were prepared: water infusion of the fresh fruiting bodies (B1), dehydrated fruiting bodies (B2), fresh mycelium (M1), and dehydrated mycelium (M2). Polysaccharides from the fresh mycelium were also obtained by water infusion followed by ethanol treatment (EP). The extracts were tested against Candida albicans, Escherichia coli, and Bacillus subtilis. To investigate the antineoplasic effect of P. ostreatus, the culture broth in natura, the extract from the culture broth (ECB), and the extract from the fruiting bodies were tested in female Swiss albino mice inoculated with the Ehrlich ascitic tumor (EAT). B1, B2, and M1 showed more than 50.0% inhibition against C. albicans. M2 presented a high degree of inhibition against E. coli (87.5%) and B. subtilis (57.5%), while EP was not effective. All the tested substances inhibited the development of EAT at levels near 70% when injected intraperitoneally in mice. The highest tumor inhibition (76%) was achieved for the treatment with ECB. The intragastric treatment did not promote any reduction in tumor cell development, independent of the test substance.     

Evaluation of Glycosyl Hydrolases in the Secretome of <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis> and Saccharification of Alkali-Treated Rice Straw

A thermotolerant Aspergillus fumigatus strain isolated from composting pile of mixed industrial waste was found to produce a spectrum of cellulase and hemicellulases when cultured on rice straw solidified substrate. The two-dimensional electrophoresis (2DE) resolved the secretome into 57 distinct protein spots. The zymograms developed against 2DE gels identified the presence of three β-glucosidases and five CBHI/EGI isoforms in the secretome. The peptide mass fingerprinting of 17 protein spots by liquid chromatography mass spectrometry characterized the secretome into different glycosyl hydrolase families. The enzyme cocktail produced by A. fumigatus was capable of efficient hydrolysis of alkali pretreated rice straw (at 7% and 10% w/v) resulting in 95% and 91% saccharification, respectively.     

Cellulose and microcrystalline cellulose from rice straw and banana plant waste: preparation and characterization

As part of continuing efforts to prepare cellulose and microcrystalline cellulose (MCC) from renewable biomass resources, rice straw and banana plant waste were used as the available agricultural biomass wastes in Egypt. The cellulose materials were obtained in the first step from rice straw and banana plant waste after chemical treatment, mainly applying alkaline-acid or acid-alkaline pulping which was followed by hypochlorite bleaching method. The results indicate a higher α-cellulose content, 66.2 %, in case of acid-alkaline treatment for rice straw compared to 64.7 % in case of alkaline-acid treatment. A low degree of polymerization, 17, was obtained for the cellulose resulting from acid–alkaline treatment for banana plant waste indicating an oligomer and not a polymer, while it reached 178 in case of the cellulose resulting from alkaline–acid treatment for the rice straw. MCC was then obtained by enzymatic treatment of the resulting cellulose. The resulting MCC show an average diameter ranging from 7.6 to 3.6 μm compared to 25.8 μm for the Avicel PH101. On the other hand, the morphological structure was investigated by scanning electron microscopy indicating a smooth surface for the resulting cellulose, while it indicates that the length and the diameter appeared to be affected by the duration of enzyme treatment for the preparation of MCC. Moreover, the morphological shape of the enzyme treated fibers starts to be the same as the Avicel PH101 which means different shapes of MCC can be reached by the enzyme treatment. Furthermore, Fourier transform infrared spectroscopy was used to indicate characteristic absorption bands of the constituents and the crystallinity was evaluated by X-ray diffraction measurements and by iodine absorption technique. The reported crystallinity values were between 34.8 and 82.4 %, for the resulting cellulose and MCC, and the degree of crystallinity ranged between 88.8 and 96.3 % dependent on the X-ray methods and experimental iodine absorption method.     

ACTION SPECTRA FOR HYPHAL AGGREGATION,THE FIRST STAGE OF FRUITING,IN THE BASIDIOMYCETE Pleurotus ostreatus*

Abstract. Action spectra were determined for hyphal aggregation in Pleurotus ostreatus at wavelengths between 360 and 600 nm. The action spectrum for a 50% response had two maxima, one at 370 nm in the near-UV and the other a broad peak at 440–450 nm in the blue. Both were approximately of the same magnitude. A minimum was present at 400 nm and wavelengths greater than 530 nm invoked no response. Action spectra for a range of responses, 10–90%, were also determined which showed gradual changes in the peaks in the blue region. It was concluded that hyphal aggregation in P. ostreatus is under the control of a cryptochrome-like photoreceptor system.     

Isolation and purification of lignoperoxidase from the mushroom <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis>

The accumulation dynamics of lignolytic enzymes in culture media of the basidiomycetes Panus tigrinus, Pleurotus ostreatus, Fomes fomentarus, and the micromycete Aspergillus terreus were studied during the incubation period. It was found that Pleurotus ostreatus is the most active producer of lignoperoxidase enzymes among the studied fungi. Gel filtration and ion-exchange chromatography were used to isolate a homogeneous enzyme with lignoperoxidase activity. The maximum activity was found at pH 2.7 and 29°C. Gel electrophoresis determined the molecular weight (44 kDa). __________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 564–566, November–December, 2007.     

Performance of Pleurotus ostreatus Mushrooms and Spent Substrate for the Biosorption of Cd(II) From Aqueous Solution

The capacities of Pleurotus ostreatus mushroom and spent substrate were evaluated for the biosorption of cadmium (II) from aqueous solution in order to select the most efficient material for bioremediation. The optimum sorption conditions were optimized, including the pH of the aqueous solution, contact time, biomass dosage, initial metal concentration, and temperature. The sorption of cadmium on both biosorbents was also evaluated by several kinetic, equilibrium, and thermodynamic models. The possible heavy metal biosorption mechanisms were evaluated through point of zero charge (pH_pzc), Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDX). Based on the results of column studies, the effectiveness of the P. ostreatus spent substrate was confirmed as a biosorbent for Cd(II) removal from aqueous solutions.     

Supplementation with Magnesium Salts—A Strategy to Increase Nutraceutical Value of Pleurotus djamor Fruiting Bodies

The use of substrates supplemented with minerals is a promising strategy for increasing the nutraceutical value of Pleurotus spp. The current research was performed to analyze the effect of substrate supplementation with magnesium (Mg) salts on the Mg content, biomass, and chemical composition of pink oyster mushroom (Pleurotus djamor) fruiting bodies. Before inoculation, substrate was supplemented with MgCl₂ × 6 H₂O and MgSO₄, both salts were applied at three concentrations: 210, 420, and 4200 mg of Mg per 2 kg of substrate. The harvest period included three flushes. Substrate supplementation with 4200 mg of Mg caused the most significant decrease in mushroom productivity, of about 28% for both Mg salts. The dry matter content in fruiting bodies was significantly lower in the treatment in which 210 mg of Mg was applied as MgSO₄ in comparison to the control. Supplementation effectively increased the Mg content in fruiting bodies of P. djamor by 19–85% depending on the treatment, and significantly affected the level of remaining bioelements and anions. One hundred grams of pink oyster fruiting bodies, supplemented with Mg salts, provides more than 20% of the Mg dietary value recommended by the Food and Drug Administration (FDA); thus, supplementation can be an effective technique for producing mushrooms that are rich in dietary Mg. Although P. djamor grown in supplemented substrate showed lower productivity, this was evident only in the fresh weight because the differences in dry weight were negligible. Mg supplementation increased the antioxidant activity of the fruiting bodies, phenolic compounds, and some amino acids, including L-tryptophan, and vitamins (thiamine and l-ascorbic acid).     

Effect of copper and manganese ions on activities of laccase and peroxidases in three Pleurotus species grown on agricultural wastes

Copper (Cu²⁺) and manganese (Mn²⁺) ions influenced laccase (Lac) and peroxidase production in Pleurotus eryngii, Pleurotus ostreatus, and Pleurotus pulmonarius. In P. eryngii, the optimum Cu²⁺ concentration for Lac production was 1 mM and for peroxidases 10mM, and Mn²⁺ concentration of 5mM led to peaks of Lac and peroxidase activity. In P. ostreatus HAI 493, the highest level of Lac activity was at Cu²⁺ concentrations of 1 and 10 mM and Mn²⁺ concentration of 1mM, respectively. The absence of Cu²⁺ and Mn²⁺ caused the highest levels of peroxidase production. In P. ostreatus HAI 494, the highest level of Lac activity was at a Cu²⁺ concentration of 5 mM and at Mn²⁺ concentration of 1 mM, respectively. High levels of peroxidase activity were found in the medium without and with 1mM Cu²⁺, and at 1 and 5 mM Mn²⁺, respectively. In P. pulmonarius, the highest Lac activity was found in the presence of 5 mM Cu²⁺ and 5 mM Mn²⁺, respectively. The absence of Cu²⁺ and Mn²⁺ as well as their presence at a concentration of 1 mM led to the peaks of peroxidase activities.     

Studies of cementitious systems with new generation by-products from fluidised bed combustion

The rate of heat evolution as well as total heat output are strongly affected by other components of hydrating mixture, apart from neat portland cement, such as slag, fly ash and other industrial by-products; among them the wastes from fluidised bed combustion (FBC) has been taken into account recently. In this study the calorimeter was applied to follow the early hydration of cements produced with these materials. They interact with cement paste in a few ways: as set controlling agent and as active pozzolanic admixtures. Thus the rate of heat evolution/hydration is modified, depending on the composition of clinker and percentage of waste in the mixture. After the series of measurements for clinker-waste mixture hydrated systems also some ‘model’ mixtures were investigated to separate the effects from particular waste components. This revised version was published online in July 2006 with corrections to the Cover Date.     

Solid-state fermentation of lignocellulosic plant residues from Brassica napus by Pleurotus ostreatus

Solid-state fermentation (SSF) of inedible parts of rapeseed was carried out using a white-rot fungus, Pleurotus ostreatus, to degrade lignocellulosic material for mycelial-single cell protein (SCP) production. This SSF system has the potential to be adapted to a controlled ecological life support system in space travel owing to the lack of storage space. The system for converting lignocellulosic material to SCP by P. ostreatus is simple; it can be carried out in a compact reactor. The fungal vegetative growth was better with a particle size of plant material ranging from 0.42 to 10 mm, whereas lignin degradation of the lignocellulose was the highest with particle sizes ranging from 0.42 to 0.84 mm. The addition of veratry alcohol (3,4-dimethoxybenzyl alcohol), hydrogen peroxide, and glycerol promotes lignocellulose degradation by P. ostreatus. The enhancement of bioconversion was also observed when a gas-flow bioreactor was used to supply oxygen and to maintain the constant moisture of the reactor. With this reactor, approx 85% of the material was converted to fungal and other types of biomass after 60 d of incubation.     

Biodegradation of cotton straw byPleutorus florida

Cotton straw is an unutilized waste product containing 25% lignin, thus making it unsuitable for use as animal feed. This material was found to be an excellent substrate for the growth of the edible mushroomPleurotus florida. A growth-promoting flavonoid was isolated from the water-soluble fraction of the straw (Platt et al., 1983). After 3 wk of fungal growth on native cotton straw, an 18% decrease in dry weight occurred. Lignin (insoluble in 72% H₂SO₄) was degraded from the 8th d of growth up to a total of 65% of the original content after 21 d. Prior to lignin degradation, sugars and other water-soluble materials were removed and laccase activity (substrate, 2,6-dimethoxyphenol) was detected. This activity disappeared after the eighth day of growth. In all our experiments it appears that laccase activity precedes the onset of lignin degradation. Cellulase activity reached a maximum after 8 d of fungal growth and immediately disappeared. Total fungal activity was estimated by measuring hydrolysis of fluorescein diacetate (FDA), which indicated a gradual increase during the first 8 d and then reached a plateau. Release of glucose from the straw by commercial cellulase increased with duration of fungal growth from 28 (Μ/g/h^-1 to 250 Μg/g/h^-1. These results are corroborated by information from artificial rumen experiments showing an increase of in vitro dry matter digestability from 26 to 38%. In comparison, on washed straw, FDA and laccase activity was three-fold smaller. Final dry weight reduction was 10.1%, while total lignin loss was only 33% of the original lignin content. It seems that the water-soluble materials are responsible for the rapid growth, increased enzymatic activity, and total degradation of cotton straw byP. florida.     

TG–FTIR analysis applied to the study of thermal behaviour of some edible mushrooms

The article is devoted to the study on the thermal behaviour of three species of edible mushrooms: Boletus edulis (foot and cap), Pleurotus ostreatus (foot and cap), Lactarius deterrimus (cap) by the TG–FTIR-coupled technique, in air, over the 30–900 °C temperature range. The analysis of the TG–DTG–DTA curves reveals the thermal degradation mechanism to be complex and specific to every species under the recording conditions applied. A similar degradation mechanism is noticed for the foot and cap of Pleurotus ostreatus in comparison with the Boletus edulis and Lactarius deterrimus species where the mechanisms are different. The TG–FTIR analysis, combustion heats and IR spectra of the starting samples also support these results. The initial degradation temperatures from TG–DTG indicate the temperature range where these species are thermally stable and their nutrient features maintained making them proper for food. The TG–FTIR analysis gives information on the gaseous species evolved by the thermal degradation bringing thus a contribution to the elucidation of the changes developing by processing the edible mushrooms (industrialization, conservation, culinary preparations, etc.) at temperatures above the initial degradation temperature. At the same time, the environmental impact, when the mushroom failed cultures are burned, is also important.