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1.
Growth and differentiation of mycelial strands in Rigidoporus lignosus have been shown to depend on suitable combinations of the pH of the media and the nature of the nitrogen and carbon sources. Amino acids as sole nitrogen sources gave rise to vegetative mycelium. At pH 4.5, growth and mycelial strand differentiation required asparagine, as the fungus failed to grow in the absence of this amino acid. However, at pH 6, differentiation of strands occurred appreciably in asparagine-deficient media, suggesting a close balance between pH and amino acid requirements. Ammonium was required for strand differentiation, while nitrate, as a sole nitrogen source, maintained the fungus undifferentiated. Of the carbohydrates tested, only glucose, fructose and mannose supported strand differentiation. Starch was found to be particularly effective in promoting growth of vegetative mycelium. Strand differentiation required more specific conditions than growth of the vegetative mycelium. 相似文献
2.
Purification and characterization of an aflatoxin degradation enzyme from Pleurotus ostreatus 总被引:3,自引:0,他引:3
Nineteen fungi were tested for their ability to degrade aflatoxin B1 (AFB1). An extracellular enzyme from the edible mushroom Pleurotus ostreatus showed afaltoxin-degradation activity detected by thin-layer chromatography (TLC). An enzyme with this activity was purified by two chromatographies on DEAE-Sepharose and Phenyl-Sepharose. The apparent molecular mass of the purified enzyme was estimated to be 90 kDa by SDS-PAGE. Optimum activities were found in the pH range between 4.0 and 5.0 and at 25 degrees C. Also, degradation activity of several dyes in the presence of H2O2 was tested, resulting in the detection of bromophenol blue-decolorizing activity. Based on these data, we suggest this enzyme is a novel enzyme with aflatoxin-degradation activity. Fluorescence measurements suggest that the enzyme cleaves the lactone ring of aflatoxin. 相似文献
3.
Kwang-Soo Shin 《Mycoscience》1995,36(1):31-35
The oxidative degradation of syringic acid by the extracellular peroxidase ofPleurotus ostreatus was studied. Three products formed in the oxidation of syringic acid by the peroxidase in the presence of O2 and H2O2 were identified as 2,6-dimethoxyphenol, 2,6-dimethoxy-1,4-dihydroxybenzene, and 2,6-dimethoxy-1,4-benzoquinone. A free radical was detected as the reaction intermediate of the extracellular peroxidase-catalyzed oxidation of acetosyringone. These results can be explained by mechanisms involving the production of a phenoxy radical and subsequent decarboxylation. This is the first time that 2,6-dimethoxyphenol has been identified in extracellular peroxidase-catalyzed reactions. 相似文献
4.
Laccase (EC 1.10.3.2) from the culture filtrate of a strain of white rot basidiomycetePleurotus ostreatus was purified using DEAE-Toyopearl 650M and butyl-Toyopearl 650M column chromatographies and Superdex 75 HR 10/30 fast protein
liquid chromatography. Molecular weight of the purified laccase was about 55,000, and the isoelectric point was 3.0. The optimum
pH for enzyme activity was 6.5, and the optimum temperature was 50°C. This enzyme contained 7.4% sugar and two copper atoms
per molecule. The substrate specificity was similar to those of other fungal laccases. Comparison of the N-terminal amino
acid sequence of theP. ostreatus laccase with those fromPleurotus ostreatus Florida,Coriolus hirsutus, Phlebia radiata, basidiomycete PM1 (CECT 2971),Trametes villosa, Pycnoporus cinnabarinus, Ceriporiopsis subvermispora, andAgaricus bisporus showed 95, 65, 60, 55, 55, 55, 50, and 35% similarity, respectively, in the first 20 residues. No similarity in this region
was detected with laccases fromNeurospora crassa, Aspergillus nidulans, andCryptococcus neoformans. 相似文献
5.
Bonomo RP Cennamo G Purrello R Santoro AM Zappalà R 《Journal of inorganic biochemistry》2001,83(1):67-75
The conformation changes in solution of three fungal laccases in different environmental conditions were examined by circular dichroism (CD) and electron paramagnetic resonance (EPR) spectroscopy. CD measurements indicate that the secondary structure of proteins depends slightly on the pH or ionic strength, though the presence of salt could interfere in the molecular recognition process between substrates and enzymes. The enzymes, however, are highly destabilized by prolonged exposure to low pH or high temperature. The observed unfolding of the proteins coincides with their inactivation and, in some cases, with precipitation. On the other hand, these conditions do not determine the disruption of the geometric arrangement of their metal centres, and this fact suggests that these centres represent the more stable core of the proteins. 相似文献
6.
Lihua Liu Zhiwei Lin Teng Zheng Ling Lin Chuanqi Zheng Zhanxi Lin Shihua Wang Zonghua Wang 《Enzyme and microbial technology》2009,44(6-7):426-433
Laccase is a widespread group of multi-copper enzymes which can catalyze the oxidation of a variety of organic compounds, with concomitant reduction of molecular oxygen to water. It has a wide application in industrial processes, particularly in renewable bio-energy industry. In this study, Pleurotus ostreatus strain 10969 with high yield of laccase, previously isolated from edible fungus growing on Juncao, was applied for optimization of fermentation media and growth parameters for the maximal enzyme production through response surface methodology and further characterization of the laccase activity. The results show that glucose and Mg2+ are the key ingredients for laccase production with the optimum concentration of 0.0988 g/mL and 7.3 mmol/L respectively. Compared to the initial medium, the highest laccase yield observed is approximately increased by 2.5 times under the optimized conditions. Extracellular laccase was then purified and its characters were analyzed. The molecular weight of the laccase is about 40 kDa, and the optimum pH and temperature for its activity is 4.0 and 50 °C with the corresponding Km and Vmax of 0.31 mmol/L and 303.25 mmol/min respectively. DTT, β-mercaptoethanol and NaN3 nearly inhibit all activity of the laccase, as well as the metal ions especially Ag+. In summary, our results will facilitate the utilization of plant lignin in biomass energy industry. 相似文献
7.
Maity KK Patra S Dey B Bhunia SK Mandal S Das D Majumdar DK Maiti S Maiti TK Islam SS 《Carbohydrate research》2011,346(2):2451-372
A water soluble polysaccharide isolated from the hot aqueous extract of Pleurotusostreatus cultivar was found to contain d-glucose and d-galactose in a molar ratio of nearly 7:1. Structural investigation was carried out using acid hydrolysis, methylation analysis, periodate oxidation, Smith degradation, and NMR studies (1H, 13C, DEPT-135, TOCSY, DQF-COSY, NOESY, ROESY, HMQC, and HMBC). On the basis of the above mentioned experiments the structure of the repeating unit of the polysaccharide was established as:This heteroglycan stimulates macrophages, splenocytes, and thymocytes. 相似文献
8.
Comparative characterization of four laccases from Trametes versicolor concerning phenolic C-C coupling and oxidation of PAHs 总被引:1,自引:0,他引:1
Koschorreck K Richter SM Swierczek A Beifuss U Schmid RD Urlacher VB 《Archives of biochemistry and biophysics》2008,474(1):213-219
The laccase genes lccα, lccβ, lccγ and lccδ encoding four isoenzymes from Trametes versicolor have been cloned and expressed in Pichia pastoris. Biochemical characterization allowed classification of these laccases into two distinct groups: Lccα and Lccβ possessed higher thermal stability, but lower catalytic activity towards 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) compared to Lccγ and Lccδ. Activities of the laccases were quite different as well. Laccase Lccδ showed highest phenolic C-C coupling activity with sinapic acid, but lowest oxidizing activity towards polycyclic aromatic hydrocarbons (PAHs). Highest activity towards PAHs was observed with Lccβ. After 72 h, more than 80% of fluorene, anthracene, acenaphthene and acenaphthylene were oxidized by Lccβ in the presence of ABTS. Investigation of the structural basis of the different activities of the laccases demonstrated the impact of positions 164 and 265 in the substrate binding site on oxidation of PAHs. 相似文献
9.
Intergeneric hybridization between Pleurotus ostreatus and Schizophyllum commune was studied using PEG-induced fusion. The fusion of protoplasts from auxotrophic mutant strains resulted in the formation of fusion hybrids in the frequencies of 3.6 to 7.3×10–5. Most of these fusion hybrids were monokaryotic and sterile and no heterokaryosis occurred. Most fusants showed a significantly higher nuclear DNA content when compared to parental strains and no diploids (parent 1 genome plus parent 2 genome) were found. Some fusion hybrids revealed both parental fragments in nuclear and mitochondrial rDNA PCR profiles. AP-PCR (Arbitrarily-primed Polymerase Chain Reaction) fingerprints also indicated that most of the fusion products were recombinant hybrids. 相似文献
10.
Marnyye A. Velázquez-Cedeño Gerardo Mata Jean-Michel Savoie 《World journal of microbiology & biotechnology》2002,18(3):201-207
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. 相似文献
11.
Nona Mikiashvili Solomon P. Wasser Eviatar Nevo Vladimir Elisashvili 《World journal of microbiology & biotechnology》2006,22(9):999-1002
Summary The effect of various carbon and nitrogen sources on laccase, manganese-dependent peroxidase (MnP), and peroxidase production by two strains of Pleurotus ostreatus was investigated. The maximal laccase yield of P. ostreatus 98 and P. ostreatus 108 varied depending upon the carbon source from 5 to 62 U l−1 and from 55 to 390 U l−1, respectively. The highest MnP and peroxidase activities were revealed in medium supplemented by xylan. Laccase, MnP, and peroxidase activities of mushrooms decreased with supplementation of defined medium by inorganic nitrogen sources. Peptone followed by casein hydrolysate appeared to be the best nitrogen sources for laccase accumulation by both fungi. However, their positive effects on enzyme accumulation were due to a higher biomass production. The secretion of MnP and peroxidase by P. ostreatus 108 was stimulated with supplementation of casein hydrolysate to the control medium since the specific MnP and peroxidase activities increased 15-fold and 3.5-fold, respectively. 相似文献
12.
A study was conducted to determine the spatial distribution of somatic incompatibility groups (SIGs) in Rigidoporus lignosus populations responsible for white root disease in a south Sumatera rubber plantation. Most isolates colonizing the stumps were somatically compatible with isolates from either a nearby stump or a living rubber tree, which suggested evidence of stump-to-tree or stump-to-stump clonal growth of the fungus. SIGs of R. lignosus occupied an area territorially in which the minimum size estimate for the largest genotype was 25m in length. 相似文献
13.
Biodegradation of soil-adsorbed polycyclic aromatic hydrocarbons by the white rot fungus Pleurotus ostreatus 总被引:2,自引:0,他引:2
Facundo J. Márquez-Rocha Vanessa Z. Hernández-Rodríguez Rafael Vázquez-Duhalt 《Biotechnology letters》2000,22(6):469-472
The white rot fungus, Pleurotus ostreatus, metabolized four soil adsorbed polycyclic aromatic hydrocarbons: 50% of pyrene (0.1 mg g–1 dry soil), 68% of anthracene and 63% of phenanthrene were mineralized after 21 d. Biodegradation was increased to 75%, 80% and 75%, respectively of the initial concentration when 0.15% Tween 40 was added. Biodegradation of pyrene in the presence of surfactant and H2O2 (1.0 mM) was 90%. Benz[a]pyrene was also oxidized by Pleurotus ostreatus but it is not mineralized. 相似文献
14.
A Gram-positive bacterium was isolated from a rottingPleurotus ostreatus fruiting body that markedly reduced the level of extracellular toxins (i.e., tolaasins) produced byPseudomonas tolaasii, the most destructive pathogen of cultivated mushrooms. The isolated bacterium is saprophytic but not parasitic nor pathogenic
toP. ostreatus. A low ratio, ca. 10−3 cells of the isolated bacterium for oneP. tolaasii cells, was sufficient for detoxification in vitro. Inoculation of the isolated bacterium prevents the development of bacterial
disease inP. ostreatus andAgaricus bisporus. The suppression of the disease development, however requires the initial cell density equivalent to ca. 10−1 cells of the isolated bacterium for one cells of the pathogen. The effects is ascribed to the inactivation of tolaasin by
the live, suppressive bacterial cells, and not to metabolites secreted from the organism into culture media. Examination by
conventional bacteriological tests and with testing kits, i.e., MicroStationTMSystem Release 3.5 (Biolog Inc., Hayward, CA), ATB Expression (bioMerieux Inc. Japan) and VITEK (bioMerieux Inc. Japan), failed
to assign the organism to any defined bacterial genus. The suppressive bacterium may be useful in future for the development
of biocontrol system and/or the construction of genetically modified edible fungi resistant to the disease caused byP. tolaasii. 相似文献
15.
Ai Min Ma Lin Jun Shan Hui Jie Wang Zhao Ping Du Bi Jun Xie 《World journal of microbiology & biotechnology》2008,24(4):501-507
Hydrophobins fulfill various physiological functions in fungal development and growth, based on their mechanism of self-assembly
at hydrophilic–hydrophobic interfaces into nano-scale, amphipathic membranes. One hydrophobin with an approximate molecular
weight of 15 kDa, designated Po.HYD1, was purified from aerial hyphae of Pleurotus ostreatus strain Pm039. Ultrastructures of self-assembled films formed by Po.HYD1 on hydrophobic and hydrophilic substrates were revealed
by atomic force microscopy (AFM). A monomolecular adsorption layer, thickness ranging from 3.2 to 3.8 nm, was observed on
the surface of highly oriented pyrolytic graphite (HOPG), while a typical rodlet layer with uniform thickness of 4.2 ± 0.1 nm
formed on the mica surface. Comparison of CD spectra showed significant secondary structural changes between monomeric and
self-assembled states. The spectrum of monomeric Po.HYD1 had a maximum ellipticity at 190 nm and a minimum at 209 nm, and
that of assemblage showed the maximum at 195 nm and the minimum shifted to 215–218 nm. Po.HYD1 showed high surface activity,
based on the dramatic drop of surface tension through self-assembly at the water–air interface. Moreover, Po.HYD1 is capable
of stabilizing the emulsion consisting of water and hexane. 相似文献
16.
Ulla Moilanen Johann F. Osma Erika Winquist Matti Leisola Susana Rodríguez Couto 《Engineering in Life Science》2010,10(3):242-247
In this study crude laccases from the white‐rot fungi Cerrena unicolor and Trametes hirsuta were tested for their ability to decolorize simulated textile dye baths. The dyes used were Remazol Brilliant Blue R (RBBR) (100 mg/L), Congo Red (12.5 mg/L), Lanaset Grey (75 mg/L) and Poly R‐478 (50 mg/L). The effect of redox mediators on dye decolorization by laccases was also assessed. C. unicolor laccase was able to decolorize all the dyes tested. It was especially effective towards Congo Red and RBBR with 91 and 80% of color removal in 19.5 h despite the fact that simulated textile dye baths were used. Also Poly R‐478 and Lanaset Grey were partially decolorized (69 and 48%, respectively). C. unicolor laccase did not need any mediators for removing the dyes. However, T. hirsuta laccase was only able to decolorize simulated Congo Red and RBBR dye baths (91 and 45%, respectively) in 19.5 h without mediators. When using mediators the decolorization capability was enhanced substantially, e.g. Poly R‐478 was decolorized by 78% in 25.5 h. On the whole, both laccases showed potential to be used in industrial applications. 相似文献
17.
The effect of pH on the transformation of syringic and vanillic acids by the laccases of Rhizoctonia praticola and Trametes versicolor 总被引:1,自引:0,他引:1
Laccases (benzenediol: oxygen oxidoreductases, EC 1.10.3.2) from Rhizoctonia praticola and Trametes versicolor formed different products from syringic and vanillic acids at different pH values, but both enzymes generated the same chemicals at a particular pH. The products were separated by thin-layer and high-performance liquid chromatography. Four compounds were determined from syringic acid (m/z 168, 334, 350 and 486) at pH 6.9, but only two of these (m/z 168 and 334) were found at pH 3.5. In the case of vanillic acid two isomeric dimers (m/z 304) and 2-methoxy-1,4-benzoquinone (m/z 138) were identified. The dimers were formed at both pH values (pH 3.5 and 6.9), but 2-methoxy-1,4-benzoquinone appeared only at pH 3.5. 相似文献
18.
Two strains of Pleurotus ostreatus (IE-8 and CP-50) were grown on defined medium added with wheat straw extract (WSE). Mycelia from these cultures were used as an inoculum for solid fermentation using sugar cane bagasse (C:N=142). This substrate was used separately either as a mixture of heterogeneous particle sizes (average size 2.9 mm) or as batches with two different particle sizes (0.92 mm and 1.68 mm). Protein enrichment and production of lignocellulolytic enzymes on each particle size was compared. The effect of ammonium sulphate (AS) addition was also analyzed (modified C:N=20), this compound favored higher levels of protein content. Strain CP-50 showed the highest increase of protein content (48% on particle size of 1.68 mm) when compared to media with no additional N source. However, strain IE-8 produced the highest levels of all enzymes: xylanases (5.79 IU/g dry wt on heterogeneous particles) and cellulases (0.18 IU/g dry wt on smallest particles), both without the addition of AS. The highest laccase activity (0.040 IU/g dry wt) was obtained on particles of 1.68 mm in the presence of AS. Since effect of particle size and addition AS was different for each strain, these criteria should be considered for diverse biotechnological applications. 相似文献
19.
Pseudomonas tolaasii strain PT814 produces extracellular toxins, tolaasins, and a volatile toxin, tovsin, that are responsible for the induction
of brown blotch and rotting, respectively, in a cultivated mushroom,Pleurotus ostreatus. Insertions of single transposon mini-Tn5Km 1 into the chromosome ofP. tolaasii strain PT814 generated mutants that are pleiotropically defective in tolaasin and protease production, and altered in colony
morphology. The mutants, however, produce tovsin at the level of wild-type. Variants phenotypically similar to the pleiotropic
mutants ofP. tolaasii strain PT814 spontaneously occurred inP. tolaasii strain S8501 at 22–30°C in vitro. The occurrence of variants was significantly reduced in the presence of extracts ofP ostreatus or at a temperature of 15–20°C. ThertpA gene (rtpA=regulator gene of tolaasin production and other pleiotropic traits) isolated from aP. tolaasii strain PT814 gene library restored the wild-type phenotype in both the mini-Tn5km 1 insertion and spontaneous mutants. mini-Tn5km 1 insertions were also located in the allele ofrtpA. Nucleotide sequencing of thertpA DNA revealed an open reading frame of 2,751 bp predicted to encode a protein consisting of 917 amino acid residues with a
molecular mass of 100.6 kDa and displaying the conserved amino acid sequence of both sensor, and receiver domains of “bacterial
two-component regulators”. The data suggest that the machinery responding to environmental stimuli is essential for the pathogenic
interaction ofP. tolaasii with the mushroom. 相似文献
20.
Enzyme Activities and Chemical Changes in Wet Olive Cake after Treatment with Pleurotus ostreatus or Eisenia fetida 总被引:1,自引:0,他引:1
A laboratory experiment was conducted to evaluate the enzyme activities and chemical changes recorded in a recalcitrant phenolic-rich
waste after treatment with Pleurotus ostreatus or Eisenia fetida. The waste used was wet olive cake (alperujo in Spanish), a waste produced in huge amounts by the olive oil industry. Both P. ostreatus and E. fetida were very effective in removing phenolic compounds, the initial concentration in the wet olive cake being reduced in both
cases by around 90%. Laccase and manganese peroxidase activities were measured in the growth medium of P. ostreatus, and catechol 2,3 dioxygenase activity was only detected in the waste treated with Eisenia; these could be the main factors responsible for the oxidation of phenolic compounds. Increases of dehydrogenase and β-glucosidase
activities were detected in the degraded wet olive cake by fungi or earthworms. In comparison with the natural wet olive cake,
the degraded products had lower total organic carbon and humic acid contents but were rich in nitrogen and other nutrients,
having lower C:N ratios. In addition, the toxicity of the wet olive cake against the seeds of Lepidium sativum significantly decreased after degradation. The low toxicity as well as moderate stability and maturity recorded in the wet
olive cake treated with P. ostreatus or E. fetida imply that these products could be used as soil amendments. 相似文献