白腐菌对纸浆漂白的研究进展*

综述了白腐菌对纸浆的漂白作用。包括用于纸浆漂白的白腐菌类型,白腐菌漂白纸浆的纸浆类型,白腐菌漂白纸浆的工艺装置,以及微生物漂白存在的问题和前景。     

Antimicrobial textile treated with chitosan from Aspergillus niger mycelial waste

The waste biomass of Aspergillus niger, following citric acid production, was used as a source for fungal chitosan extraction. The produced chitosan was characterized with deacetylation degree of 89.6%, a molecular weight of 25,000 dalton, 97% solubility in 1% acetic acid solution and comparable FT-IR spectra to standard shrimp chitosan. Fungal chitosan was applied as a cotton fabric finishing agent using pad-dry-cure method. The topographical structure of chitosan-treated fabrics (CTF) was much improved compared with control fabrics. CTF, after durability tests, exhibited a powerful antimicrobial activity against both E. coli and Candida albicans, the captured micrographs for E. coli cells contacted with CTF showed a complete lysis of cell walls with the prolonging contact time. The produced antimicrobial CTF could be proposed as a suitable material for many medical and hygienic applications.     

五蕊寄生种子萌发特性

采用室内与野外实验相结合的方法,对五蕊寄生（Dendrophthoe pentandra）种子萌发特性以及鸟类消化过程对其种子萌发的影响进行研究。结果表明：五蕊寄生种子对温度和光照较敏感,与黑暗条件相比,光照能显著提高种子的萌发率;20℃为种子萌发的最适温度,萌发率达53.8%,高温35℃及低温10℃均不利于种子萌发。研究发现纯色啄花鸟（Dicaeum concolor）是该植物的主要食果者,种子外的果肉不是限制种子萌发的关键因素,人为去除果肉并不能提高种子的萌发率,但可缩短种子萌发的时间,果实通过纯色啄花鸟类肠道消化后,随着粪便排出的种子萌发率显著提高（达69%）,暗示纯色啄花鸟在五蕊寄生的种子萌发过程中具有重要的作用。     

New enzymatic immobilized biocatalysts for detoxification of organophosphorus compounds

New immobilized biocatalysts based on phosphotriesterase and porous fabric materials impregnated with chemically cross-linked chitosan and sulphate chitosan gels were investigated. Analysis of the rheological characteristics of enzyme-containing gels confirmed their high plasticity and mechanical strength, while scanning electron microscopy verified their macroporous structure. The fabric matrix could absorb and retain a large amount of liquid thereby increasing its own weight 3.5–4.5 fold. The catalytic characteristics of the immobilized biocatalyst hydrolyzing Paraoxon, Coumaphos, Chlorpyrifos and Diisopropyl fluorophosphate were investigated. The catalytic efficacy of the soluble enzyme was 3.0–5.5-times higher compared to the immobilized form mainly due to the lower K_m values. With constant 55–60% humidity the biocatalyst retained 77% and 67–70% activity after 50-day storage at 4°C and 23°C, respectively. Benzalkonium chloride appeared to be an appropriate preservative for long-term storage of immobilized biocatalyst in a wet state.     

Effect of hydrolytic and oxidative enzymes produced by solid-state fermentation on greige linen fabric

Solid state fermentation (SSF) was applied for production of fungal enzyme preparations from Phanerochaete chrysosporium, Aspergillus oryzae, Aspergillus giganteus and Trichoderma virens using cotton seed-coat fragment waste as a carbon source and enzyme inducer. Lignin-holocellulose matrix of cotton seed coat fragment proved to be effective in inducing production of ligninolytic, cellulolytic and xylanolytic enzymes in solid-state fermentation. The effect of the enzymes produced by SSF on greige linen fabric is discussed and evaluated. In the first experiment the hydrolytic and accompanying oxidative enzymes in the buffer extract of the whole SSF cultures were used for fabric treatment. In the second trial, the enzymes produced in situ (whole SSF material—mixture of fungal biomass, residual substrate and enzymes) were used for the treatment. Weight loss, reducing sugar liberation and removal of colouring materials were measured. The results showed that at equal enzyme charges the intact SSF materials were more efficient than the enzyme extracts. Of the six strains evaluated, Ph. chrysosporium VKM F-1767 was the most effective in removing colouring matters from greige linen fabric.     

Immobilization of catalase on cotton fabric oxidized by sodium periodate

Cotton fabric was first oxidized with sodium periodate, and then employed to immobilize catalase. Optimization studies for oxidation of the fabric and immobilization of the enzyme were performed. The properties of the immobilized catalase were examined and compared with those of the free enzyme. A high activity of the immobilized enzyme was obtained when the fabric was oxidized at 40°C and pH 6.0 for 8h in a bath containing 0.20 mol L^?1 sodium periodate and the enzyme was immobilized at 4°C for 24h with a catalase dosage of 120.0 U mL^?1. The immobilized enzyme exhibited optimum activity at 40°C, while the free enzyme had optimal temperature of 30°C, suggesting that the immobilized catalase could be used in a broader temperature range. Both the immobilized and free enzyme had pH optima of 7.0. The staining test and reusability showed that the catalase was fixed covalently on the oxidized cotton fabric.     

Two mannanases from Sclerotium rolfsii in total chlorine free bleaching of softwood kraft pulp

The plant pathogenic basidiomycete Sclerotium rolfsii produces a wide range of extracellular hemicellulolytic enzymes. To study the effect of β-mannanases in total chlorine free bleaching of softwood pulp, two purified β -mannanases from S. rolfsii, with molecular masses of 42 and 61 kDa, a xylanase preparation from S. rolfsii and combinations of these were tested in a O(QX)P bleaching sequence (O = oxygen delignification, X = treatment with enzymes, Q = chelation of metals, P = treatment with hydrogen peroxide in alkaline solution). A brightness increase of 1.6 and 1.9% ISO was obtained with the 42 and 61 kDa mannanase and a combination of each of these enzymes with xylanases gave a brightness increase of 2.5 and 2.8% ISO, respectively. The effect of mannanases and xylanases was nearly additive. Both mannanases alone caused a lower decrease of the kappa number as compared to xylanases. The mannanases differed in their ability to release oligosaccharides from different mannans. The 61 kDa mannanase liberated larger fragments and caused rapid depolymerisation of mannans, which seems to promote the bleaching of pulp.     

Restored perfusion and reduced inflammation in the infarcted heart after grafting stem cells with a hyaluronan‐based scaffold

The aim of this study is to investigate the blood perfusion and the inflammatory response of the myocardial infarct area after transplanting a hyaluronan‐based scaffold (HYAFF^®11) with bone marrow mesenchymal stem cells (MSCs). Nine‐week‐old female pigs were subjected to a permanent left anterior descending coronary artery ligation for 4 weeks. According to the kind of the graft, the swine subjected to myocardial infarction were divided into the HYAFF^®11, MSCs, HYAFF^®11/MSCs and untreated groups. The animals were killed 8 weeks after coronary ligation. Scar perfusion, evaluated by Contrast Enhanced Ultrasound echography, was doubled in the HYAFF^®11/MSCs group and was comparable with the perfusion of the healthy, non‐infarcted hearts. The inflammation score of the MSCs and HYAFF^®11/MSCs groups was near null, revealing the role of the grafted MSCs in attenuating the cell infiltration, but not the foreign reaction strictly localized around the fibres of the scaffold. Apart from the inflammatory response, the native tissue positively interacted with the HYAFF^®11/MSCs construct modifying the extracellular matrix with a reduced presence of collagene and increased amount of proteoglycans. The border‐zone cardiomyocytes also reacted favourably to the graft as a lower degree of cellular damage was found. This study demonstrates that the transplantation in the myocardial infarct area of autologous MSCs supported by a hyaluronan‐based scaffold restores blood perfusion and almost completely abolishes the inflammatory process following an infarction. These beneficial effects are superior to those obtained after grafting only the scaffold or MSCs, suggesting that a synergic action was achieved using the cell‐integrated polymer construct.     

Thermo-responsive non-woven scaffolds for "smart" 3D cell culture

The thermo‐responsive polymer poly(N‐isopropylacrylamide) has received widespread attention for its in vitro application in the non‐invasive, non‐destructive release of adherent cells on two dimensional surfaces. In this study, 3D non‐woven scaffolds fabricated from poly(propylene) (PP), poly(ethylene terephthalate) (PET), and nylon that had been grafted with PNIPAAm were tested for their ability to support the proliferation and subsequent thermal release of HC04 and HepG2 hepatocytes. Hepatocyte viability and proliferation were estimated using the Alamar Blue assay and Hoechst 33258 total DNA quantification. The assays revealed that the pure and grafted non‐woven scaffolds maintained the hepatocytes within the matrix and promoted 3D proliferation comparable to that of the commercially available Algimatrix? alginate scaffold. Albumin production and selected cytochrome P450 genes expression was found to be superior in cells growing on pure and grafted non‐woven PP scaffolds as compared to cells grown as a 2D monolayer. Two scaffolds, namely, PP‐g‐PNIPAAm‐A and PP‐g‐PNIPAAm‐B were identified as having far superior thermal release capabilities; releasing the majority of the cells from the matrices within 2 h. This is the first report for the development of 3D non‐woven, thermo‐responsive scaffolds able to release cells from the matrix without the use of any enzymatic assistance or scaffold degradation. Biotechnol. Bioeng. 2012; 109:2147–2158. © 2012 Wiley Periodicals, Inc.