Molecular mass and chain conformation of carboxymethylated derivatives of beta-glucan from sclerotia of Pleurotus tuber-regium

Seven water-insoluble (1 --> 3)-beta-D-glucan fractions TM8-1 to TM8-7 with weight-average molecular mass M(w) ranged from 2.22 to 77.4 x 10(4) obtained from the sclerotia of Pleurotus tuber-regium were carboxymethylated to produce the water-soluble fractions CTM8-1 to CTM8-7 with M(w) ranged from 3.87 to 87.8 x 10(4). The degree of substitution (DS) of CTM8 fractions was analyzed by ir and elemental analysis (EA) to be 0.3-0.68. The M(w) and the intrinsic viscosity [eta] of the CTM8 fractions were measured by size-exclusion chromatography combined with multiangle laser light scattering (SEC-MALLS), MALLS, and viscometry in phosphate buffer solution (PBS) at 37 degrees C. The dependencies of [eta] and radius of gyration (z) (1/2) on M(w) for the CTM8 samples were found to be [eta] = (8.82 +/- 0.03) x 10(-3) M(w)(0.78 +/- 0.04) (cm(3) g(-1)) and (z) (1/2) = (3.09 +/- 0.05) x 10(-3) M(w)(0.75 +/- 0.06) (nm) in the M(w) range from 3.87 x 10(4) to 53.2 x 10(4). Based on current theories for wormlike chain model, the conformational parameters of the CTM8 were obtained to be 790 (nm(-1)) for M(L), 9.6 (nm) for q, which were higher than those of the native TM8 fractions, suggesting a more extended flexible chain of CTM8 in PBS. On the whole, the CTM8 fractions showed higher antitumor activity than their corresponding TM8 fractions. In view of data from molecular parameters and bioactivity, the antitumor activity of the CTM8 fractions may be correlated to its water solubility and relatively extended chain.     

Comparative study on the growth and yield of<Emphasis Type="Italic"> Pleurotus ostreatus</Emphasis> mushroom on different lignocellulosic by-products

Eight lignocellulosic by-products were evaluated as substrates for cultivation of the oyster mushroom, Pleurotus ostreatus (Jacq. ex. fr) Kummer. The yields of mushroom on the different substrates were 183.1, 151.8, 111.5, 87.8, 49.5, 23.3, 13.0 and 0.0 g for composted sawdust of Triplochiton scleroxylon, rice straw, banana leaves, maize stover, corn husk, rice husk, fresh sawdust, and elephant grass, respectively. The biological efficiency (BE) followed the same pattern and ranged from 61.0% for composted sawdust to 0.0% for elephant grass. The yield of mushroom was positively correlated to cellulose (r ² =0.6), lignin (r ² =0.7) and fibre (r ² =0.7) contents of the substrates. Based on the yield and BE of the substrates tested, rice straw appeared to be the best alternate substrate for growing oyster mushrooms. Electronic Publication     

Screening of Pleurotus ostreatus isolates for their ligninolytic properties during cultivation on natural substrates

Thirteen basidiospore-derived isolates of Pleurotus ostreatus f6 strain differing in the level of ligninolytic enzyme production and other characteristics (mycelium extension rate, colony morphology) from the parental strain were cultivated on natural substrates. Under these conditions ligninolytic enzyme activity, loss of organic mass, polycyclic aromatic hydrocarbons (PAHs) degradation and colonization of sterile and nonsterile soil were studied. The activity of ligninolytic enzymes was substantially higher in straw than in liquid culture, although the differences between the isolates were less pronounced on this substrate. Some of the isolates showed a very good ability to decompose the lignocellulosic substrate (straw) and a relatively high loss of organic mass was found after 50 days of cultivation in these strains. The original strain f6 and isolates B13 and B26 successfully degraded all seven tested PAH compounds present in experimental soil samples, but the higher or lower ligninolytic enzyme production of isolates tested had no substantial effect on the extent of the degradation. In our screening, six basidiospore-derivedisolates growing well in nonsterile soil were found, whichcould be suitable for the prospective biotechnological exploitation.     

rtpA, a gene encoding a bacterial two-component sensor kinase, determines pathogenic traits ofPseudomonas tolaasii, the causal agent of brown blotch disease of a cultivated mushroom,Pleurotus ostreatus

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.     

The use of a white rot fungi (Pleurotus ostreatus) immobilized on Amberlite XAD-4 as a new biosorbent in trace metal determination

The present work proposes the use of Pleurotus ostreatus immobilized on Amberlite XAD-4 as new biosorbent in trace metal determination. The effects of experimental parameters, such as “pH and flow rate of sample solution, amount of solid phase, eluent type, and concentration” on the recovery of the metal ions were investigated. Maximum adsorption of Cr(III), Cd(II) and Cu(II) ions took place in the pH range 4-5. These metal ions can be desorbed with 1 M HCl (recovery 95-100%). 0.2 g adsorbent amount and 2.5 mL min⁻¹ flow rate was found to be optimum of all preconcentration experiments. The sorption capacity after 10 cycles of sorption and desorption does not vary more than 2.0%. The influences of the contaminant ions on the retentions of the analytes were also examined. The results showed that P. ostreatus immobilized on Amberlite XAD-4 can be considered as very promising material in trace metal determination.     

Ligninolytic enzymes activities of Oyster mushrooms cultivated on OMW (olive mill waste) supplemented media, spawn and substrates

Ligninolytic enzymes activities (laccases, peroxidases (total, MnP and MiP) and aryl-alcohol oxidase (AAO)) were measured during the cultivation of six commercial Pleurotus sp. strains on MMP media, on cereal grains (spawn) and on straw substrates (the three commonly utilized cultivation steps to obtain fruiting bodies) supplemented with several concentrations of autoclaved (OMW) or gamma-irradiated (iOMW) olive mill waste. Results indicated that all the strains were able to grow on MMP media and spawn containing up to 30% OMW and iOMW and on straw substrates mixed with 50% OMW. None of the strains showed AAO activity and there was not a single strain which showed the highest laccases and peroxidases activities, independently of the utilized substrate. Pleurotus mycelia adjusted their enzymatic mechanisms depending on their variety, type of substrate, concentration of OMW or iOMW added. OMW was a better supplement to use than iOMW because OMW induced higher exo-enzymes activities.     

Response Surface Analysis of Solid State Growth of <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis> Mycelia utilizing Whey Permeate

A novel approach to utilizing whey permeate, the cultivation of mycelia of the edible mushroom Pleurotus ostreatus, is introduced. Response surface analysis (RSA) was successfully applied to determine the combination of substrate concentration, temperature and pH that would result in a maximal mycelial extension rate under solid state cultivation. The conditions to maximize the mycelial extension rate were predicted to be 44 g lactose l⁻¹, pH 6.0 and 24.2 °C. Subsequent verification of these levels agreed with model predictions.     

Evaluation of sulfated fungal beta-glucans from the sclerotium of Pleurotus tuber-regium as a potential water-soluble anti-viral agent

Six water-insoluble fractions of fungal beta-glucans extracted by hot alkali (TM8-1 to TM8-6) from the sclerotia of Pleurotus tuber-regium (PTR) having different molecular weights (M(w)) were sulfated to give their corresponding water-soluble derivatives (S-TM8-1 to S-TM8-6) with the degree of sulfation (DS) ranging from 1.14 to 1.74. The in vitro anti-viral activities of the native beta-glucans (TM8s) and their sulfated derivatives (S-TM8s) were evaluated by the cytopathic effect assay (CPE) and the plaque reduction assay (PRA) against four kinds of viruses, including herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2), respiratory syncytial virus (RSV), and influenza A virus (Flu A). Although TM8s were inactive in inhibiting the viral replication in cell cultures, the S-TM8 fractions with the defined M(w) range had potent anti-viral activity against HSV-1 and HSV-2 as shown by the CPE assay. The PRA results suggested that S-TM8 fractions seemed to exert their anti-viral effect by binding to the viral particles, preventing the latter from infecting the host cells. It was plausible that the negative charges on the polymer chain of S-TM8 could interact with the positively charged glycoproteins on the surface of HSV, minimizing the interaction between the HSV and the negatively charged host cells. The anti-viral activity of the S-TM8s might also be explained by their more extended chain conformation in solution due to an increase in one of their molecular parameter, persistence length (q), as compared to the native TM8s. The potential use of S-TM8s as a water-soluble anti-HSV agent is discussed.     

5种珍稀食药用真菌活性提取物对果蝇寿命影响的研究

探讨了松茸、栎金钱菌、蜂窝菌、云芝、杏鲍菇活性提取物对果蝇寿命的影响,分别用这5种食药用真菌活性提取物各以5、20g/L的剂量加入培养基中培养果蝇,观察其对果蝇寿命的影响.结果表明,松茸、栎金钱菌、蜂窝菌、云芝、杏鲍菇的活性提取物能显著延长果蝇的平均寿命和半数死亡时间,其平均寿命延长率分别达23.96%、53.22%、23.09%、32.58%、20%.这提示松茸、栎金钱菌、蜂窝菌、云芝、杏鲍菇都具有良好的延寿效果.     

Use of Pleurotus dryinus for lignocellulolytic enzymes production in submerged fermentation of mandarin peels and tree leaves

It has been shown that the wood-rotting mushroom Pleurotus dryinus IBB 903 is able to effectively produce cellulases, xylanase, laccase, and manganese peroxidase in submerged fermentation of mandarin peels and tree leaves. Gradual increasing of lignocellulosic substrates concentration from 1 to 4–6% enhanced enzyme accumulation in culture liquid. A simple and inexpensive medium containing mandarin peels and yeast extract as sole carbon and nitrogen sources allowed simultaneous production of high levels of both hydrolases and oxidases by P. dryinus IBB 903. Supplementation of this medium by copper and manganese caused earlier and faster accumulation of laccase and manganese peroxidase increasing their yield by 1.5 and 7.5 times, respectively. In addition, by adding manganese to the medium it is possible to regulate the ratio of laccase and MnP in enzyme preparation. The presence of lignocellulosic substrate is the requisite for MnP production by P. dryinus IBB 903 since there was no production of MnP when mushroom has been cultivated in the synthetic medium with different carbon source. Among carbon source tested only utilization of glucose resulted to 21-fold increase of fungus laccase specific activity compared to control medium without carbon source. Carboxymethyl cellulase and xylanase appeared to be inducible enzymes.