Modification of high-lignin softwood kraft pulp with laccase and amino acids

This study demonstrates the potential of laccase-facilitated grafting of amino acids to high-lignin content pulps to improve their physical properties in paper products. Research studies have recently reported that increases in anionic fiber charge can improve strength properties of paper. In an effort to increase carboxylic acid groups, we developed a unique two-stage laccase grafting protocol in which fibers were initially treated with laccase followed by grafting reactions with amino acids. The bulk acid group content was measured, and a variety of amino acids including glycine (Gly), phenylalanine (Phe), serine (Ser), arginine (Arg), histidine (His), alanine (Ala), and aspartic acid (Asp) were examined. The effects of optimizing laccase dose, and amino acid structures, on fiber modification chemistry were studied. Histidine provided the best yield of acid groups on pulp fiber, and was used for the preparation of handsheets for physical strength testing. Laccase-histidine treated pulp showed an increase in strength properties of the resulting paper.     

Assessment of wood-inhabiting Basidiomycetes for biokraft pulping of softwood chips

Wood-inhabiting Basidiomycetes have been screened for various applications in the pulp and paper industry and it is evident that different fungi need to be used to suit the specific requirements of each application. This study assessed the suitability of 278 strains of South African wood-decay fungi for the pre-treatment of softwood chips for kraft pulping. The influence of these fungi on kappa number, yield and strength properties of pulp was evaluated. A number of these strains were more efficient in reducing kappa number than the frequently used strains of Phanerochaete chrysosporium and Ceriporiopsis subvermispora. Six strains of Stereum hirsutum and a strain of an unidentified species were able to reduce the kappa number significantly without a significant influence on the pulp yield. Treatment of wood with two strains of S. hirsutum, one strain of Peniophora sp. and a strain of an unidentified species resulted in paper with improved strength properties.     

Catalytic properties of endoxylanase fusion proteins from Neocallimastix frontalis and effect of immobilization onto metal-chelate matrix

The production of hybrid enzymes with novel properties and the research for new methods for enzyme immobilization in bioreactors are of major interest in biotechnology. We report here the second part of a study concerning the improvement of the properties of the endoxylanase XYN3A4 from the anaerobic fungi Neocallimastix frontalis. The effects of gene fusion and immobilization on metal-chelate matrix are also compared for the reference enzymes XYN3, XYN3A, XYN4 used for the construction of the fusion protein XYN3A4. The influence of the metal ion in the immobilization process was first investigated and best immobilization yields were obtained with the Cu(II) ion whereas best coupling efficiencies were reached with the Ni(II) ion. It was also observed that XYN3, XYN3A and XYN34 had a lower rate of hydrolysis when immobilized on Ni(II)-IDA and more difficulties to accomodate small substrates than the soluble enzymes. Nevertheless, a major difference was noted during the hydrolysis of birchwood xylan and it appears that the reaction using the immobilized XYN3A4 chimeric enzyme leads to the accumulation of a specific product.     

Biosoftening of coir fiber using selected microorganisms

Coir fiber belongs to the group of hard structural fibers obtained from coconut husk. As lignin is the main constituent of coir responsible for its stiffness, microbes that selectively remove lignin without loss of appreciable amounts of cellulose are extremely attractive in biosoftening. Five isolated strains were compared with known strains of bacteria and fungi. The raw fiber treated with Pseudomonas putida and Phanerocheate chrysosporium produced better softened fiber at 30±2 °C and neutral pH. FeSO₄ and humic acid were found to be the best inducers for P. chrysosporium and P. putida, respectively, while sucrose and dextrose were the best C-sources for both. Biosoftening of unretted coir fibers was more advantageous than the retted fibers. Unlike the weak chemically softened fiber, microbial treatment produced soft, whiter fibers having better tensile strength and elongation (44.6–44.8%) properties. Scanning electron microscopy photos showed the mycelia penetrating the pores of the fiber, removing the tylose plug and degrading lignin.     

Effect of Fine-Grain Percent on Soil Strength Properties Improved By Biological Method

In many civil engineering projects, the foundation soils do not provide the required mechanical properties and therefore, there is a need to improve the soil. Compaction, soil reinforcement, soil mixing with natural, or chemical additives are common soil stabilization methods used to improve the soil mechanical properties. The incidence of some environmental problems in traditional improvement techniques has encouraged engineers to explore new methods. Recently in this category, a new technique in geotechnical engineering called biogeotechnology is introduced to improve the mechanical properties of the soil. It is an environmentally friendly approach that uses biological methods to solve geotechnical problems. This technique uses minerals producer microorganisms. This study investigates the possibility of improving soil strength properties with microbial calcite precipitation and the effect of fine-grained percentages in this regard. In order to determine the soil strength properties, consolidated drained direct shear tests have been carried on untreated and treated soil samples. The results showed that this method is applicable to improve all soil samples (from 100% coarse-grained (i.e., sand) to 100% fine-grained (i.e., clay)). However, increasing the strength in the sand is much more enhanced than that for finer soils. It was found that a considerable increase in cohesion of treated soil can be achieved for soil samples with maximum 10% fine content.     

Mycelial paper: A potential resource recovery process?

Eleven species of fungi representative of a broad range of cell-wall compositions were evaluated with respect to their papermaking potential as additives to woodpulp furnishes. Some of these species were also examined for their ability to grow on a spent liquor from the pulp-and-paper industry. Handsheets with various levels of incorporated mycelia exhibited a wide range of species-dependent properties. Behavior of the mycelia in the sheets can be modified to a degree by physical and chemical treatments. The overall results suggest that small amounts (5–10% of the sheet constituents) of mycelia, grown inexpensively on waste effluents, might be incorporated into wood fiber paper without serious deleterious effects on paper strength properties. In some cases improved paper is obtained, and larger quantities of mycelia might be used to impart specific properties to the product.     

Do the unique properties of nanometals affect leachability or efficacy against fungi and termites?

Nanotechnology has the potential to affect the field of wood preservation through the creation of new and unique metal biocides with improved properties. This study evaluated leachability and efficacy of southern yellow pine wood treated with copper, zinc, or boron nanoparticles against mould fungi, decay fungi, and Eastern subterranean termites. Results showed that nanocopper with and without surfactant, nanozinc, and nanozinc plus silver with surfactant resisted leaching compared with metal oxide controls. Nearly all nanoboron and boric acid was released from the treated wood specimens during leaching. Mould fungi were moderately inhibited by nanozinc oxide with surfactant, but the other nanometal preparations did not significantly inhibit mould fungi. Mass loss from Gloeophyllum trabeum was significantly inhibited by all copper preparations, while Antrodia sp. was not inhibited by nanometal treatments. Nanometals imparted high resistance in southern yellow pine to the white-rot fungus, Trametes versicolor. Unleached specimens treated with nanoboron or nanozinc plus surfactant caused 100% and 31% mortality, respectively. All specimens treated with nanozinc or nanozinc plus silver inhibited termite feeding, but the copper treatments were less effective against termites. Nanozinc possessed the most favorable properties: leach resistance, termite mortality, and inhibition of termite feeding and decay by the white-rot fungus.     

AM真菌在植物病虫害生物防治中的作用机制

丛枝菌根(Arbuscular Mycorrhizae,AM)真菌是一类广泛分布于土壤生态系统中的有益微生物,能与大约80%的陆生高等植物形成共生体。由土传病原物侵染引起的土传病害被植物病理学界认定为最难防治的病害之一。研究表明,AM真菌能够拮抗由真菌、线虫、细菌等病原体引起的土传性植物病害,诱导宿主植物增强对病虫害的耐/抗病性。当前,利用AM真菌开展病虫害的生物防治已经引起生态学家和植物病理学家的广泛关注。基于此,围绕AM真菌在植物病虫害生物防治中的最新研究进展,从AM真菌改变植物根系形态结构、调节次生代谢产物的合成、改善植物根际微环境、与病原微生物直接竞争入侵位点和营养分配、诱导植株体内抗病防御体系的形成等角度,探究AM真菌在植物病虫害防治中的作用机理,以期为利用AM真菌开展植物病虫害的生物防治提供理论依据,并对本领域未来的发展方向和应用前景进行展望。     

Improvement of the physical properties of reprocessed paper by using biological treatment with modified cellulase

A primary need for waste paper reprocessing is to preserve optical properties and the physical strength of the paper fibers. In this study, modified cellulase with copolymer, polyethylene oxide (PEO) derivatives and maleic anhydride (MA) was applied to the reprocessing of mixed office waste (MOW). Modified cellulase was prepared by a chemical reaction between amino groups of the cellulase and the MA functional groups of the copolymer. In MOW reprocessing, modified cellulase improved several physical properties of the paper including freeness, optical properties, and physical strength compared to the conventional process. Even though native cellulase improved the physical properties, paper treated with modified cellulase exhibited an increase in physical properties such as tensile strength and internal bond over those of unmodified cellulase. From these results, modified cellulase method is a new biological treatment that will save pulp resources, which are added to waste paper reprocessing to maintain the strength of paper.     

Endophytic Phomopsis sp. colonization in Oryza sativa was found to result in plant growth promotion and piperine production

Endophytic fungi have been reported to have the acquired ability to synthesize host plant specific medicinal natural products. Many fungi with such properties have been characterized and optimized for the conditions which favor maximal production of desired products. However, the inherent plant colonization property of promising endophytic fungi is least studied. Exploiting the transgenome functioning of these fungi have immense applications to add beneficial features to nonhost plants. In the present study, the endophytic fungus Phomopsis sp. isolated from Piper nigrum was confirmed for piperine production by HPLC and LCMS/MS. Further, the fungal isolate was studied for its colonization ability in Oryza sativa. Interestingly, the fungi treated plants were found to have significant plant growth enhancement when compared to the control. Further screening of extract from treated plants by HPLC and LCMS/MS resulted in the confirmation of presence of piperine. The observed result is extremely significant as it opens up novel applications of endophytic fungal colonization in taxonomically diverse plants.     

Physicochemical properties of the exocellular polysaccharide from Cyanospira capsulata

This paper reports on the chemical structure and on some physicochemical properties of a new exopolysaccharide, CC-EPS, secreted by a filamentous nitrogen-fixing cyanobacterium, Cyanospira capsulata. Solution properties of CC-EPS were studied with the aim of characterizing the conformational state of the polysaccharide in water and in aqueous salt solution, in view of the peculiar rheological properties. Because the molecule has two different uronic acid residues, a variation of pH and/or ionic strength was considered to be the best perturbation to disclose any possible ordered structures. We found no evidence for a cooperative conformational transition from the change of the chiro-optical properties or from the smooth increase of pKa as a function of the degree of ionization, alpha, of the polyacid. The same conclusion was drawn from the study of the temperature dependence and ionic strength dependence (in the range up to 0.1 M NaCl) of solution properties. The data suggest that the solution conformation of CC-EPS is a random coil with a chain flexibility comparable to that of alginate.     

湿垃圾来源的蚯蚓粪肥对连作障碍土壤质量和黄瓜产量的影响

随着城市化的发展,湿垃圾产量与日俱增,湿垃圾资源化利用迫在眉睫。利用蚯蚓处理湿垃圾制作蚯蚓粪肥用于农田土壤改良,是一项有效的湿垃圾资源化利用途径以及有利于缓解蔬菜连作障碍方面问题。该文以常规有机肥为参照,选取以湿垃圾及其厌氧沼渣为原料制作的蚯蚓粪肥为研究对象,研究连续3年施加蚯蚓粪肥对黄瓜(Cucumis sativus)土壤综合质量和作物产量的影响。结果表明,经过3年的改良后,施加60.0 t/hm²蚯蚓粪肥的黄瓜产量提高了5.60%,土壤有机质含量提高了50.0%,且蚯蚓粪肥的效果要高于常规有机肥;土壤全氮含量达到最高,高于背景值33.0%;土壤的养分含量(硝态氮、速效磷、速效钾)也得到了提高,其中速效钾含量升高了94.0%。经过3年的改良,土壤中的细菌数量在施加了有机肥后明显增加,其中以添加30.0t/hm²蚯蚓粪肥的细菌数量最多;土壤细菌/真菌的比值有所提高,土壤生物性状得到改善。土壤的呼吸强度随着有机肥的施入而升高,以施加60.0t/hm²蚯蚓粪肥的最大;土壤pH略有降低,盐度无明显变化。因此,湿垃圾来源的蚯蚓...     

Utilization of acrylates emulsion terpolymer with chitosan as a finishing agent for cotton fabrics

Cotton fabrics were treated with finishing bath formulation containing emulsion lattices based on acrylate monomers, chitosan and polyethylene glycol (PEG) to provide cotton fabrics with antibacterial, UV-protection as well as improvement of dyeing properties with direct, acid and reactive dyes. The terpolymer emulsion, chitosan and PEG concentrations as well as fabric pretreatment with alkali significantly affected the performance properties, antimicrobial activity, UV-protection and dyeing behavior of treated cotton fabric. The finished fabrics were characterized in terms of FTIR, X-ray diffraction, scanning electron microscope (SEM) as well as mechanical properties such as tensile strength, elongation at break (%), abrasion resistance and air permeability. The obtained data showed that the tested fabrics have appropriate antibacterial activity with highly UV-protection properties with increasing chitosan concentration up to 3%. The mechanical properties expressed as tensile strength and abrasion resistance increased after finishing treatment. Moreover, the performance of the finished fabrics and dyeing properties with different dyes classes were greatly influenced by the action of alkali pretreatment of cotton fabrics, adding the polyethylene glycol to the finishing bath formulation as well as emulsion and chitosan concentrations.     

Fungi recovered from root-knot nematodes infecting vegetables under protected cultivation

A survey was conducted in root-knot nematode-infested plastic houses to determine the diversity and frequency of occurrence of fungi associated with the nematode. The relationships between percentage fungal parasitism and physicochemical properties of soil were also investigated. Fifty-nine plastic houses were sampled in southeastern Spain, 42 treated with nematicides and 17 left untreated. Eleven fungal genera and unidentified fungi were isolated from nematode eggs or juveniles. Fungal parasitism occurred more frequently in untreated (82.4%) than treated (50%) soils. The species richness in untreated soils ranged from 0 to 5, the Shannon–Wiener diversity index (a measurement of how many different fungi there are in site taking into account how evenly they are distributed among the site) from 0 to 2.01, and the evenness index from 0.46 to 0.99. In treated soils, species richness ranged from 0 to 4, the Shannon–Wiener diversity index from 0 to 1.61, and the evenness index from 0.81 to 1. Of the sites with nematophagous fungi, Arthrobotrys dactyloides (34%), Cylindrocarpon sp., Neosartoria hiratsukae (17%), and Fusarium solani (14%) were the fungi most frequently found. Physicochemical properties of soil were similar in nematicide treated and untreated soils. Percent fungal parasitism in untreated soils correlated positively with lime, silt and carbonate content of soil.     

Evaluation of thermally modified Grevillea robusta heartwood as an alternative to shortage of wood resource in Kenya: Characterisation of physicochemical properties and improvement of bio-resistance

Heat treatment of Grevillea robusta, a tropical wood species of low natural durability, was carried-out under inert conditions to improve its decay resistance. Resistance of heat treated samples was evaluated by malt agar block tests after three months of exposure to several wood rotting fungi. Also resistance of heat treated wood against termites was tested in the laboratory and in the field. Results showed that durability against fungi and termites was greatly improved after treatment. There was a good correlation between decay resistance and mass loss due to thermal treatment. Microscopic, FTIR and (13)C MAS NMR analysis were performed to characterize wood chemical and anatomical modifications that occur after treatment to understand the reasons of the durability improvement.     

Novel pre-treatment processes to promote linen-containing fabrics properties

This study was undertaken to investigate the effect of plasma pre-treatment, followed by enzymatic treatment in the absence and presence of bleaching agent on the properties of linen and linen-containing fabrics. Different plasma gases (air, oxygen and nitrogen), enzymes (acid-cellulases, neutral-cellulase and alkaline-pectinase) as well as bleaching agents (peracetic acid and H₂O₂) were used. The changes in physico-mechanical properties, surface morphology and dyeing properties of the treated substrates have been investigated. The obtained results indicated that plasma pre-treatment followed by subsequent acid-cellulases/peracetic acid or alkaline-pectinase/H₂O₂ treatment result in: a dramatic improvement in hydrophilicity and wettability as well as in the degree of whiteness of the treated substrates, an improvement in reduction of surface roughness and extent of post-reactive dyeing, along with a weight loss and a drop in the tensile strength. The extent of surface modification as well as the changes in the above-mentioned properties are governed by the characteristics of the substrate, the plasma gas, the nature and dose of the used enzyme, as well as the type of bleaching agent and additive. The optimal treatment sequence for attaining better performance properties was O₂-plasma followed by alkaline-pectinase/H₂O₂ treatment in presence of PEG 400.     

Development of environmentally-benign wood preservatives based on the combination of organic biocides with antioxidants and metal chelators

Wood extractives can be envisaged to protect heartwood by at least three different mechanisms, i.e. fungicide, free radical scavengers/antioxidants and as metal chelators. In short-term laboratory decay tests using two different wood species and decay fungi, the combination of different organic fungicides with various antioxidants and/or metal chelators gave enhanced activity as compared to the organic biocide alone, with the best results usually obtained with all three compounds. Outdoor ground-contact stakes treated with a biocide and antioxidant combination and exposed for 30 months also gave enhanced protection against both decay fungi and termites. It was concluded that the combination of an organic biocide with metal chelating and/or antioxidant additives gives enhanced protection to wood against fungi as compared to the biocide alone and, consequently, it may be possible to develop environmentally-benign wood preservative systems based on this idea.     

Mechanical properties and decay resistance of wood-polymer composites prepared from fast growing species in Turkey

Some mechanical properties of wood-polymer composites from maritime pine (Pinus pinaster Ait.) and poplar (Populus x. euramericana cv. I-214) wood were investigated. Three different monomers; styrene (ST), methyl methacrylate (MMA) and styrene/methyl methacrylate (ST/MMA) mixture were used in preparation of wood-polymer composites (WPCs). Full-loading (FL), half-loading (HL) and quarter-loading (QL) were used as polymer content levels. Untreated pine and pine-polymer composite samples were tested in compression strength parallel to grain and static bending strength. WPCs mechanical properties increased compared to untreated wood. The polymer had greater effect on the strengths of the ST/MMA treated pine than on the ST and MMA treated pine samples. Increasing of the mechanical properties should improve the structural competitiveness of WPCs made from fast growing-low density woods. Weight losses due to fungal attack for pine and poplar-polymer composites were also determined. Although polymers at full and half loading levels helped decreasing weight losses due to both fungi for each wood species, weight losses were still found to be higher.     

Changes in microorganisms populations in the soil after fumigation

Soil fumigation with dazomet, metam sodium, chloropicrin and chloropicrin + 1.3 D resulted in significant decrease of fungi and increase of bacteria populations in trials carried out in four farms located in different areas. Depending on the farm and the active substance applied, the fungi population was decreased by 1.4- to 3500-fold in comparison to control. Metam sodium and chloropicrin showed the best efficacy, both of them almost totally eliminated the fungi from the soil environment.The total number of bacteria was increased by the chemical fumigation with all tested products. While the population of fluorescent Pseudomonads in all treated plots increased from 2- to 100-fold, depending on the farm, the number of Bacillus spp. was not changed or decreased compared with non fumigated soil.The nematology analysis of the soil indicated that any chemical fumigant significantly limited the population of plant parasitic nematodes, which number was, anyway, below the damage threshold. However, in most cases dazomet and metam sodium reduced the total number of all nematodes present in the soil.The fumigation with chloropicrin and 1,3 D at dose of 30 g/m2 resulted in an increase of the total number of all nematodes in soil.     

Improvement of shrink-resistance and tensile strength of wool fabric treated with a novel microbial transglutaminase from Streptomyces hygroscopicus

In this study, a novel microbial transglutaminase (MTG) from Streptomyces hygroscopicus WSH03-13 was applied in the processing of wool fabrics. The results indicated that MTG treatment could improve felting properties and decrease tensile strength loss of wool fabrics. For the wool fabrics used in this study, MTG treatment following chemical and protease pretreatment led to a 2.32% of area shrinkage and about 16% recovery in tensile strength based on the samples without MTG treatment. Moreover, a traditional resin treatment was compared with the role of MTG. Although the tensile strength of wool fabrics treated by MTG was lower than that treated by resin treatment, the fabrics had similar anti-felting properties, and the chemical oxygen demand of wastewater was only half of the latter.