白腐菌对木质素降解能力的测定

本文测定了7种霉菌对木质素的降解作用。结果表明,在测试的7种霉菌中,米曲霉(Aspergillus oryzal)2013、米曲霉2014、米曲霉2015和黑曲霉(Aspergillus niger)对木质素的降解能力较强,其降解率均达到90%以上。野外分离得到的细菌对木质素没有降解作用。     

层孔菌产漆酶的摇瓶最适培养条件研究

筛选到一株高产漆酶的层孔菌W－1,对其兴体产漆酶的培养条件进行了优化,确定了最适的碳源、氮源,并用正交试验确定了培养基中碳源和氮源的浓度。在最优化的培养条件下,培养7d后,W－1产生的漆酶活力可以达到7．1U／mL。采用补料的方法,可以得到大量的漆酶粗酶液。     

Oxidase of the white rot fungus Panus tigrinus 8/18

Extracellular oxidase of the white rot fungus Panus tigrinus earlier reported as laccase)contains copper but has no absorption spectrum typical of ‘blue’ oxidases. Thioglycolate and sodium azide inhibit the activity of this enzyme at concentrations 2.5–3 orders lower than those needed for fungal laccases. The oxidase of P. tigrinus oxidizes syringaldazine, coniferyl alcohol, ABTS, syringic acid, diaminobenzidine, guaiacol, catechol and vanillylacetone with different efficiencies. Oxygen consumption and no hydrogen peroxide formation were detected during substrate oxidation by P. tigrinus oxidase. It is proposed that P. tigrinus oxidase is a new ligninolytic enzyme.     

Taxonomic identification of Streptomyces exfoliatus K10 and characterization of its poly(3-hydroxybutyrate) depolymerase gene

Abstract Using fungi grown on synthetic agar medium, we evaluated and compared the concentration of various H₂O₂-producing enzymes. Our results showed that oxidase production in solid medium was better than that found in liquid medium and as high as that detected in wood samples. High yields of oxidases made it possible to compare different oxidases in the same culture extracts and under different conditions. Our results also indicated that H₂O₂ production is ubiquitous in the white rot fungi tested and that enzyme levels are influenced by the substrate composition.     

贝壳状革耳菌和黄孢平革菌固体培养酶系比较

白腐菌黄孢平革菌(Phanerochaete chrysosporium)与贝壳状革耳菌(Panus conchatus)在类似自然状态的固体培养条件下酶的分泌情况有较大差异。P.conchatus和P.chrysosporium的主要木素降解酶分别是漆酶和锰过氧化物酶;两种菌均产生较高水平的木聚糖酶;P.conchatus在整个培养过程中所产生的内切葡聚糖酶、微晶纤维素酶和纤维二糖酶活力均比P.chrysosporium相应酶的活力低得多,尤其是内切葡聚糖酶。研究结果初步揭示了P.conchaus降解木素的主要酶系及选择性降解木素的原因。     

Modification of malachite green by Fomes sclerodermeus and reduction of toxicity to Phanerochaete chrysosporium

Malachite green (MG) is a triphenylmethane dye used as a fungicide but also possesses a high toxicity to mammalian cells. The toxicity of MG to Fomes sclerodermeus and Phanerochaete chrysosporium was assessed. P. chrysosporium was highly sensitive to the dye and it was unable to grow on solid media containing 64 microM of MG, lower concentrations caused a delay in growth. The radial growth of F. sclerodermeus was not affected at this concentration and up to 128 microM. In liquid media both fungi were more sensitive. F. sclerodermeus not only was able to grow in the presence of high concentrations of MG, but also it was able to decolorize and detoxify the dye. MG treated with supernatants containing high laccase activity in the presence or absence of 1-hydroxybenzotriazole (1-HBT) gave a colorless product (DMG) that was not toxic to P. chrysosporium and other white rot fungi tested. On the basis of the data of maximal absorbance, it is probable that the mechanism involved in the modification of the dye was different if 1-HBT was added to the reaction.     

Laccase production and simultaneous decolorization of synthetic dyes in unique inexpensive medium by new isolates of white rot fungus

Morphological and biochemical analysis of the newly isolated white rot fungal (WRF-1) strain has ability to secrete laccase in the economical medium consisted of synthetic dyes, groundnut shell (GNS) and cyanobacterial biomass (algal bloom) under submerged shaking condition at pH 5.0 and 30 °C ± 2 °C temperature. WRF-1 strain was found to decolorize synthetic dyes efficiently at pH 5.0 and 30 °C ± 2 °C temperature. The laccase activity of strain was purified to homogeneity by chromatography with yield up to 70%. The molecular mass of laccase was found to be 70 kDa by SDS-PAGE and isoelectric point was 4.8. Biotransformation of the dyes was followed spectrophotometrically and dyes were found to decolorize completely after 6 days of fermentation. LC-MS studies were used to decipher the degradation profile of synthetic dyes by WRF-1. Indigo carmine gets degraded to isatin sulfonic acid and 4-amino-3-methylbenzenesulphonic acid whereas methyl orange degraded metabolites were identified as p-N,N′-dimethylamine phenyldiazine and p-hydroxybenzene sulfonic acid. Thus the study would give a road map for the production and application of laccase enzyme on a larger scale using low cost substrate.     

A critical review of the application of white rot fungus to environmental pollution control

Research on white rot fungi for environmental biotechnology has been conducted for more than 20 years. In this article, we have reviewed processes for cell growth and enzyme production including the factors influencing enzyme productivity and the methods for enhancement of enzyme production. Significant progress has been achieved in molecular biology related to white rot fungi, especially related to the extraction of genetic material (RNA and DNA), gene cloning and the construction of genetically engineered microorganisms. The development of biotechnologies using white rot fungi for environmental pollution control has been implemented to treat various refractory wastes and to bioremediate contaminated soils. The current status and future research needs for fundamentals and application are addressed in this review.     

固定化白腐真菌对多种染料脱色的研究*

白腐真菌F17Schizophyllumsp.对不同结构的多种染料具有较强的脱色能力。聚酯无纺布是该菌固定化的最佳载体。利用正交实验,确定了该菌株固定化细胞制备的最优操作条件。与游离菌相比,固定化菌不仅提高其脱色能力,而且在pH值和染料浓度的变化情况下,仍保持稳定的脱色率。固定化菌对染料脱色后的紫外可见光谱分析表明,可见光区吸收峰消失,紫外区的光吸收峰有所增加,染料结构发生了变化。     

Oligomers of 4-chloroaniline are intermediates formed during its biodegration by Phanerochaete chrysosporium

Abstract Lignin peroxidase H2 (LP-H2) from Phanerochaete chrysosporium oxidized 4-chloroaniline to form several oligomers. Included among the compounds identified were: 4,4'-dichloroazobenzene, 2-(4-chloroanilino)-5-hydroxybenzoquinone-di-4-chloroanil and 2-amino-5-(4-chloroanilino) benzoquinone-di-4-chloroanil. In contrast to results by other, we showed that oligomers of 4-chloroaniline were also formed by the fungus in vivo. It was also demonstrated that, although these potentially toxic intermediates are made, they are also degraded.     

The Isolation of Soluble Proteins,Glycoproteins, and Proteoglycans from Bone

Procedures are described for the isolation from bone of fractions containing proteins, glycoproteins and proteoglycans. Extraction of powdered bone with solutions of the sodium salts of ethylendiaminetetra-acetic acid (EDTA) at pH 7.5 solubilised about 7% of the organic material. These extracts contained about 1.8% of the total collagen and at least 60% of the total non-collagenous protein of bone. The extracts were dialysed against water to remove EDTA and then against a pH 5 buffer. At this stage a precipitate (Cl) formed which was removed by centrifugation. The supernatant was applied to a column of the carboxylio ion-exchange resin, Amberlite CG-50. The effluent at pH 5 contained the proteoglycans and more-acidic glycoproteins and was therefore named the Acidic Fraction (AF). The material adsorbed to the resin (Fraction G2) was eluted by equilibration to pH 8. AF was further fractionated by cetylpyridinium chloride (CPC) precipitation into three relatively pure components:(i) CP-S, a glycoprotein soluble in CPC, (ii) bone sialoprotein (BSP) which formed a CPC precipitate soluble in 0.2M-MgCl₂; and (iii) a proteoglycan fraction which formed a CPC precipitate insoluble in 0.2M-MgCl₂. The G2 fraction contained most of the soluble collagen together with glycoproteins and other non-collagenous proteins. These were fractionated by chromatography on DEAE-cellulose at pH 7.2 using stepwise elution with increasing concentrations of NaCl. Some resolution of the mixture was obtained, though most of the fractions contained more than one component. These procedures have been used on an analytical scale to assess the yields and recoveries of total protein, hydroxyproline and sialic acid in the fractions described above. This has been compared with the large scale procedure for the preparation of the fractions, which have been studied in previous work.     

Resistance of phenolic-treated oil palm stem plywood against subterranean termites and white rot decay

The objectives of the study were to evaluate the effectiveness of phenolic resin in protecting oil palm stem (OPS) plywood against both subterranean termites (Coptotermes curvignathus) and white rot fungi (Pycnoporous sanguineus). Specially cooked, Low molecular weight phenol formaldehyde (LMW PF) resin was used to treat the OPS veneer whilst commercial urea formaldehyde (UF) resin was used to bond the phenolic-treated veneer. OPS plywood were produced using two types of lay-up (100% outer veneer type and 100% inner veneer type) with adhesive spread rate of 200 g/m². The results show that treatment of OPS veneer with LMW PF has significantly enhanced the resistance of OPS plywood against both termites and white rot fungi. In the termites resistance test, the percentage of weight loss for untreated samples were 19.2% (outer veneer) and 23.9% (inner veneer), while for phenolic treated samples were only 10.7% and 15.8%, respectively. The phenolic treatment was able to enhance the resistance towards termites by 38% and towards white rot fungi by 62%. The study has shown LMW PF resin can be used to protect OPS plywood from termites and white rot fungi.     

Decolorization of reactive dyes by a thermostable laccase produced by Ganoderma lucidum in solid state culture

Dye decolorizing potential of the white rot fungus Ganoderma lucidum KMK2 was demonstrated for recalcitrant textile dyes. G. lucidum produced laccase as the dominant lignolytic enzyme during solid state fermentation (SSF) of wheat bran (WB), a natural lignocellulosic substrate. Crude enzyme shows excellent decolorization activity to anthraquinone dye Remazol Brilliant Blue R (RBBR) without redox mediator whereas diazo dye Remazol Black-5 (RB-5) requires a redox mediator. Polyacrylamide gel electrophoresis (PAGE) of crude enzyme confirms that the laccase enzyme was the major enzyme involved in decolorization of either dyes. Native and SDS-PAGE indicates that the presence of single laccase with molecular weight of 43 kDa. N-Hydroxybenzotriazole (HBT) at a concentration of 1 mM was found as the best redox mediator. RB-5 (50 mg l^−l) was decolorized by 62% and 77.4% within 1 and 2 h, respectively by the crude laccase (25 U ml⁻¹). RBBR (50 mg l^−l) was decolorized by 90% within 20 h, however, it was more efficient in presence of HBT showing 92% decolorization within 2 h. Crude laccase showed high thermostability and maximum decolorization activity at 60 °C and pH 4.0. The decolorization was completely inhibited by the laccase inhibitor sodium azide (0.5 mM). Enzyme inactivation method is a good method which averts the undesirable color formation in the reaction mixture after decolorization. High thermostability and efficient decolorization suggest that this crude enzyme could be effectively used to decolorize the synthetic dyes from effluents.     

Biodegradation of bioaccessible textile azo dyes by Phanerochaete chrysosporium

Azo dyes are important chemical pollutants of industrial origin. Textile azo dyes with bioaccessible groups for lignin degrading fungi, such as 2-methoxyphenol (guaiacol) and 2,6-dimethoxyphenol (syringol), were synthesised using different aminobenzoic and aminosulphonic acids as diazo components. The inocula of the best biodegradation assays were obtained from a pre-growth medium (PAM), containing one of the synthesised dyes. The results of the dye biodegradation assays were evaluated every 7 days, by the decrease of the absorbance at the maximum wavelength of the dye, by the decrease of the sucrose concentration in the culture medium and by the increase of the biomass during the 28 days of assay. It was observed that the extent of dye biodegradation depended on the sucrose concentration, on the degraded dye structure and, on the dye present in the PAM medium.