Aryl-alcohol Oxidase Involved in Lignin Degradation Ferreira, Patricia; Hernandez-Ortega, Aitor; Herguedas, Beatriz ...
The Journal of biological chemistry,
09/2009, Letnik:
284, Številka:
37
Journal Article
Recenzirano
Odprti dostop
Aryl-alcohol oxidase (AAO) is a FAD-containing enzyme in the GMC (glucose-methanol-choline oxidase) family of oxidoreductases. AAO participates in fungal degradation of lignin, a process of high ...ecological and biotechnological relevance, by providing the hydrogen peroxide required by ligninolytic peroxidases. In the Pleurotus species, this peroxide is generated in the redox cycling of p-anisaldehyde, an extracellular fungal metabolite. In addition to p-anisyl alcohol, the enzyme also oxidizes other polyunsaturated primary alcohols. Its reaction mechanism was investigated here using p-anisyl alcohol and 2,4-hexadien-1-ol as two AAO model substrates. Steady state kinetic parameters and enzyme-monitored turnover were consistent with a sequential mechanism in which O2 reacts with reduced AAO before release of the aldehyde product. Pre-steady state analysis revealed that the AAO reductive half-reaction is essentially irreversible and rate limiting during catalysis. Substrate and solvent kinetic isotope effects under steady and pre-steady state conditions (the latter showing ∼9-fold slower enzyme reduction when α-bideuterated substrates were used, and ∼13-fold slower reduction when both substrate and solvent effects were simultaneously evaluated) revealed a synchronous mechanism in which hydride transfer from substrate α-carbon to FAD and proton abstraction from hydroxyl occur simultaneously. This significantly differs from the general mechanism proposed for other members of the GMC oxidoreductase family that implies hydride transfer from a previously stabilized substrate alkoxide.
In this study, total saponins were extracted from Pleurotus ostreatus cultivated with Astragalus as one of organic culture substrates. High Performance Thin Layer Chromatography (HPTLC) assay showed ...total saponins could be separated effectively, and four kinds of spots were identified as AG I, AG II, AG III, and AG IV, respectively. FTIR spectra based on HPTLC separation assay showed the saponin characteristic groups including ‐OH, C‐H, C=O, and the glycoside linkaged to sapogenin group C‐O‐C, suggesting the four kinds of spots belonged to cycloartane‐type triterpene saponins. The primary mass spectra of precursor ion (HPTLC‐ESI‐MS) assay further proved the main composition of four kinds of spots was AG I‐IV, respectively. Physical properties, including the detection of specific rotation and melting point, revealed the separation of high‐purity saponin monomer by HPTLC. HPTLC‐dual wavelength spectrodensitometric method detection showed that content of astragaloside I‐IV was ranged from 0.2 to 0.5 mg/g, and the total astragalosides contents attained to 1.397 mg/g, indicating P. ostreatus could bioaccumulate astragalosides from Astragalus. These results demonstrated the characterization of astragalosides based on the separation of HPTLC was effective, and supported to consider astragalosides‐enriched P. ostreatus as functional edible fungus for food and medical applications.
Practical Application
Currently, the consumption of enriched foods has become common and continues to increase due to urgent demanding for foods with high nutritional value. Pleurotus ostreatus is a functional edible fungus, which not only can produce secondary metabolites, but can enrich bioactive ingredients. Astragalosides have a wide range of biological activities, especially currently being tested as cardioprotective agent. In this study, P. ostreatus was cultivated through adding Astragalus into culture substrates, which realized massive enrichment of astragalosides. Astragalosides‐enriched P. ostreatus as functional edible fungus could be extensively used in food and medical areas, especially for the prevention of cardiovascular diseases.
The Pleurotus eryngii species-complex comprises choice edible mushrooms growing on roots and lower stem residues of Apiaceae (umbellifers) plants. Material deriving from extensive sampling was ...studied by mating compatibility, morphological and ecological criteria, and through analysis of ITS1-5.8S-ITS2 and IGS1 rRNA sequences. Results revealed that P. eryngii sensu stricto forms a diverse and widely distributed aggregate composed of varieties elaeoselini, eryngii, ferulae, thapsiae, and tingitanus. Pleurotuseryngii subsp. tuoliensis comb. nov. is a phylogenetically sister group to the former growing only on various Ferula species in Asia. The existence of Pleurotusnebrodensis outside of Sicily (i.e., in Greece) is reported for the first time on the basis of molecular data, while P. nebrodensis subsp. fossulatus comb. nov. is a related Asiatic taxon associated with the same plant (Prangos ferulacea). Last, Pleurotusferulaginis sp. nov. grows on Ferulago campestris in northeast Italy, Slovenia and Hungary; it occupies a distinct phylogenetic position accompanied with significant differences in spore size and mating incompatibility versus other Pleurotus populations. Coevolution with umbellifers and host/substrate specificity seem to play key roles in speciation processes within this fungal group. An identification key to the nine Pleurotus taxa growing in association with Apiaceae plants is provided.
•rRNA sequences were used for the phylogenetic analysis of Pleurotus eryngii complex.•Morphological, ecological, and compatibility data also contributed at delimiting taxa.•Pleurotus ferulaginis sp. nov. and two new taxonomic combinations are proposed.•Coevolution with Apiaceae plants is of importance for the speciation of this complex.•A dichotomous key is provided for Pleurotus taxa associated with umbellifers.
Pleurotus ostreatus and
Pleurotus sajor-caju were studied for their ability to produce laccase and carboxymethylcellulase (CMCase) enzymes on different agricultural wastes under solid state ...fermentation. The spawns of
P. ostreatus and
P. sajor-caju were inoculated on different agricultural wastes including viticulture wastes, wheat straw, paddy straw, sesame straw, sawdust as well as the mixtures of these wastes with wheat bran. The carbon and nitrogen contents of substrates containing bran were the highest. The laccase activities of
P. ostreatus and
P. sajor-caju reached the highest values on the day 10 of mycelial growth. This enzyme activity was higher on the substrates containing bran which had high nitrogen and low C/N ratio than the other tested substrates with no bran. The CMCase activities of
P. sajor-caju and
P. ostreatus had two peaks on the 5th day of mycelial growth and after first flash.
P. ostreatus and
P. sajor-caju grown on substrates containing wheat bran had higher biological efficiencies and total yields as well as higher CMCase and laccase activities.
The factors selected to optimize the productivity of Pleurotus flabellatus biomass in 250ml working volume Erlenmeyer flask were agitation rate, initial pH value and incubation temperature. The ...central composite design was applied to study the significant factors and the interactions between the chosen factors, if present. The Design Expert software generated 20 runs. The optimized conditions obtained were as follows: the agitation rate of 129.8 rpm, incubation temperature at 27.8 degree C, and initial pH of 6.06. The optimized conditions tripled the productivity at the range of 980 - 1040 mg/litre/day compared to the initial rate productivity at 310 mg/litre/day. From the quadratic equation,the agitation rate, temperature and the interaction between agitation rate and temperature were found to be significant (p < 0.05). At optimum conditions, the experimental data supported the theoretical estimate.
The particular characteristics of growth and development of mushrooms in nature result in the accumulation of a variety of secondary metabolites, several of them with biological activities. The genus ...Pleurotus is a cosmopolitan group of mushrooms with high nutritional value and therapeutic properties, besides a wide array of biotechnological and environmental applications.
The present report aims to provide a critical review on aspects related to chemical compounds isolated from the genus Pleurotus with possible biotechnological, nutritional and therapeutic uses. Investigations on the genus have immensely accelerated during the last ten years, so that only reports published after 2005 have been considered.
The most important Pleurotus species cultivated in large scale are Pleurotus ostreatus and Pleurotus pulmonarius. However, more than 200 species have already been investigated to various degrees. Both basidiomata and mycelia of Pleurotus are a great renewable and easily accessible source of functional foods/nutraceuticals and pharmaceuticals with antioxidant, antimicrobial, anti-inflammatory, antitumor and immunomodulatory effects. A series of compounds have already been precisely defined including several polysaccharides, phenolics, terpenes and sterols. However, intensification of structure determination is highly desirable and demands considerable efforts. Further studies including clinical trials need to be carried out to ascertain the safety of these compounds as adequate alternatives to conventional drugs. Not less important is to extend the search for novel bioactives to less explored Pleurotus species.
•Pleurotus sp. are considered as nutraceuticals and pharmaceuticals.•Among more than 200 species, Pleurotus ostreatus and Pleurotus pulmonarius are the most consumed.•Basidiomata and mycelia of Pleurotus are rich in bioactives.•Polysaccharides, phenolics, terpenes and sterols are some of their bioactives.•As other β-glucans, Pleurotus β-glucan presents antitumoral activity.
Recently, we isolated and purified a neutral polysaccharide (PGN) from edible fungus Pleurotus geestanus. Its structure was characterized by a range of physical-chemical methods, including high ...performance anion exchange chromatography, uronic acid, and protein analyses, size exclusion chromatography with ultraviolet, refractive index and light scattering detectors, and nuclear magnetic resonance. Our results revealed that PGN is a novel -(13)-D-glucan with glucose attached to every other sugar residues at Position 6 in the backbone. It has a degree of branching of 1/2. Such structure is different from typical -(13)-D-glucans schizophyllan and lentinan in which DB is 1/3 and 2/5, respectively. Rheological study showed a very interesting melting behavior of PGN in water solution: heating PGN in water leads to two transitions, in the range of 8-12.5?C and 25-60?C, respectively. The melting behavior and conformational changes were characterized by rheometry, micro-differential scan calorimetry, atomic force microscopy, static and dynamic light scattering at different temperatures. The first heating-induced transition corresponds to the disintegration of polymer bundles into small helical clusters, resembling the heating-induced dissociation of SPG in water at 7?C; the second one might correspond to the dissociation of helical strands to individual chains. The ability of PGN to undergo a conformation/viscosity transition in water upon heating is very valuable to immobilize cells or enzymes or therapeutic DNA/RNA, which makes PGN a potentially useful biomaterial.
Fourier transform infrared (FT-IR) spectroscopy has been successfully applied for the identification of bacteria and yeasts, but only to a limited extent for discriminating specific groups of ...filamentous fungi. In the frame of this study, 73 strains – from different associated hosts/substrates and geographic regions – representing 16 taxa of the edible mushroom genus Pleurotus (Basidiomycota, Agaricales) were examined through the use of diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. A binary matrix, elaborated on the basis of presence/absence of specific absorbance peaks combined with cluster analysis, demonstrated that the spectral region 1800–600 cm−1 permitted clear delimitation of individual strains into Pleurotus species. In addition, closely related species (e.g., Pleurotus ostreatus and Pleurotus pulmonarius) or taxa of the subgenus Coremiopleurotus demonstrated high similarity in their absorbance patterns, whereas genetically distinct entities such as Pleurotus dryinus, Pleurotus djamor, and Pleurotus eryngii provided spectra with noteworthy differences. When specific regions (1800–1700, 1360–1285, 1125–1068, and 950–650 cm−1) were evaluated in respect to the absorbance values demonstrated by individual strains, it was evidenced that this methodology could be eventually exploited for the identification of unknown Pleurotus specimens with a stepwise process and with the aid of a dichotomous key developed for this purpose. Moreover, it was shown that the nature of original fungal material examined (mycelium, basidiomata, and basidiospores) had an effect on the outcome of such analyses, and so did the use of different mycelium growth substrates. In conclusion, application of FT-IR spectroscopy provided a fast, reliable, and cost-efficient solution for the classification of pure cultures from closely related mushroom species.
► DRIFT spectroscopy is a rapid and accurate method for discriminating mushroom species. ► Mycelium material is suitable for strain classification through FT-IR spectroscopy. ► FT-IR spectra are influenced by the growth media and type of biological material used. ► A novel dichotomous identification key is elaborated for Pleurotus species. ► DRIFT spectroscopy is fast, reliable, and cost-efficient for mushroom taxa delimitation.
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•Selenium application had no significant effect on the growth of P. eryngii.•The uptake ability of P. eryngii to exogenous Se was Na2SeO3 > Se yeast > Na2SeO4.•Both the boiling and ...frying treatments resulted in Se loss in P. eryngii.•Frying reduced the bioaccessibility of Se in P. eryngii, while boiling enhanced it.•Se yeast and boiling are the ideal Se source and cooking method for P. eryngii.
Understanding the effects of processing on the Se content and bioaccessibility in food is critical in guiding the development of Se-enriched products. In this study, Se-enriched Pleurotus eryngii was obtained by applying different Se supplements to the substrate. Selenium content and its bioaccessibility among raw and processed fruit bodies were compared. The application of exogenous Se had no significant effect on the yield of P. eryngii, while amendment Se yeast could slightly promote the growth of P. eryngii. The enrichment ability of P. eryngii among different Se supplements declined in the order of Na2SeO3 > Se yeast > Na2SeO4. However, the processing treatments resulted in 6.6%–45.9% Se loss. The Se bioaccessibility of P. eryngii was 78.4%–89.7%. Frying treatment reduced Se bioaccessibility in samples, whereas boiling treatment enhanced it. Therefore, Se yeast and boiling treatment are recommended as the ideal Se supplement and processing method for Se-enriched P. eryngii.
Arsenic poisoning in ground water had been major challenge for the mankind in arsenic hit areas. In India, this problem is a big alarm in the entire Gangetic belt. The arsenic poisoning through ...drinking water has caused lots of health hazards to humans especially related hepato-biliary. This present study was carried out to investigate the therapeutic role of the ethanolic extract of Pleurotus cornucopiae on Sodium Arsenite induced hepatotoxicity in rats. Sodium Arsenite at the dose of 8mg/kg-1 body weight orally caused liver damage in rats as manifested by the significant rise in serum levels of Serum Glutamic Pyruvate Transaminase (SGPT), Serum Glutamate Oxalate Transaminase (SGOT), Alkaline Phosphatase (ALP) and Bilirubin levels compared with control. Oral administration of 400mg extracts of P. cornucopiae (/kg) for 30 days to Sodium Arsenite treated rats showed significant ameleoration in these levels. Thus, the entire study reveals that ethanolic extract of P. cornucopiae at the dose of 400 mg/kg-1 body weight shows hepatoprotective effect against arsenic induced toxicity.
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