| 1. |
- Henriksson, Gunnar, 1965-, et al.
(author)
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Monocomponent endoglucanases : an excellent tool in wood chemistry and pulp processing
- 2005
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In: 13th ISWFPC (International Symposium on Wood, Fibre and Pulping Chemistry), Auckland, New Zealand, 16-19 May 2005: Proceedings. ; , s. 503-508
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Conference paper (peer-reviewed)abstract
- Highly pure cellulases of endoglucanase type produced by genetically modified fungi are commercially available. They are useful tools both for analytical wood chemistry and potentially also as industrial chemicals for novel processes for the pulp and paper industry. Here the functionality of cellulases and some application of endoglucanases are reviewed. The mechanisms behind the effects of the enzyme are discussed.
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| 2. |
- Akin, Danny E., et al.
(author)
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Progress in enzyme-retting of flax
- 2004
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In: Journal of Natural Fibers. - 1544-0478. ; 1:1, s. 21-47
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Journal article (peer-reviewed)abstract
- New methods for retting flax are sought to overcome problems in the current method of dew-retting of flax. Published data are reviewed and new data presented on the development and testing of a method to ret flax using pectinase-rich enzyme mixtures plus chelators based on cost and fiber yield and properties. In spray enzyme retting (SER), flax stems are crimped to physically disrupt the plant's protective barrier and then sprayed until soaked with, or briefly immersed in, an enzyme/ chelator formulation. Flax is then incubated at temperatures optimal for enzyme activity, washed, and dried. Pilot scale tests, conducted with 10 kg samples of flax retted with a series of formulations, showed that this method effectively retted flax stems from a variety of sources, including fiber flax, mature fiber flax, and linseed straw. Fiber yield, strength, and fineness were significantly influenced by variations in enzyme-chelator amounts. Cellulases in pectinase mixtures appeared to preferentially attack dislocations in fibers and fiber bundles resulting in loss of fiber strength. Polygalacturonases alone effectively separated fiber from non-fiber components. The SER method proved to be an effective framework for further tests on enzyme-chelator formulations that now must be integrated with physical processing to optimize the extraction of flax fibers based on cost and fiber yield and properties.
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| 3. |
- Antonsson, Stefan, et al.
(author)
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Biomimetic synthesis of suberin for new biomaterials
- 2005
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In: Appita Annual Conference. ; , s. 561-564
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Conference paper (peer-reviewed)abstract
- Suberin is the biopolymer giving cork (oak bark) its hydrophobic and resistant characteristics. It acts as a diffusion barrier in bark and roots of plants. Similarly to lignin, it is a phenolic polymer with good affinity to cellulose and other wood polysaccharides, but it also contains polyaliphatic and strongly hydrophobic elements. In order to produce a lignin derivative similar to suberin, a desired lignin starting material should be of low molecular weight and have a high content of hydroxylic phenolic groups. By means of cross flow nanofiltration of softwood kraft pulping black liquor and pH-precipitation with diluted sulphuric acid, such a lignin has been obtained. Due to the fact that too much organics entering the recovery boiler frequently is the bottleneck for pulp production increases, a removal of part of the lignin can be economically very favourable. By using this lignin together with linola oil, a linseed oil with a large amount of unsaturated structures, an attempt was made to create a new hydrophobic lignin derivative similar tosuberin. The product was analysed with FT-IR, Fourier Transformed Infra Red Spectroscopy and GPC, Gel Permeation Chromatography. The suberin like material obtained from this lignin could be polymerised on thermo mechanical pulp fibres by means of Mn(III)-driven phenolic coupling. The ability of the suberin monomers to act as a hydrophobic paper coating was evaluated with contact angle measurements and the results indicate that this lignin derivative was potentially of interest due to its capability to interact well with wood fibres and make paper hydrophobic.
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| 7. |
- Azhar, Shoaib, et al.
(author)
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Chemoenzymatic separation of softwood polymers
- 2011
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In: Proceedings of the 16th international symposium of wood, fiber and pulp chemistry. - 9787501982066 ; , s. 932-936
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Conference paper (peer-reviewed)abstract
- Spruce wood chips were chemically pre-treated with sodium hydroxide to open up the compact structure of wood. The wood was then treated with enzymes (xylanase, gamanase and mannanase) and subjected to extraction with a mixture of methanol and alkali to efficiently isolate lignin and hemicelluloses. Chemical pre-treatment improved enzyme efficiency which consequently enhanced the extraction of lignocelluloses with higher average molar mass than the references.
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| 8. |
- Azhar, Shoaib, et al.
(author)
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Extraction of polymers from enzyme-treated softwood
- 2011
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In: BioResources. - 1930-2126. ; 6:4, s. 4606-4614
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Journal article (peer-reviewed)abstract
- In a biorefinery context it is an advantage to fractionate and extract different wood components in a relatively pure form. However, one major obstacle for efficient extraction of wood polymers (lignin, polysaccharides etc.) is the covalent lignin-polysaccharide networks present in lignified cell walls. Enzymatic catalysis might be a useful tool for a controlled degradation of these networks, thereby enhancing the extraction of high molecular weight polymers. In this work, a methanol-alkali mixture was used to extract two different wood samples treated with endoxylanase and gammanase, respectively. Wood chips were pretreated with alkali prior to enzymatic treatment to enhance the cell-wall accessibility to enzymes. Extractions were also carried out on non-enzyme-treated samples to evaluate the enzymatic effects. Results showed that the enzymatic treatment increased the extraction yield, with gammanase as the more efficient of the two enzymes. Furthermore, polymers extracted from xylanase-treated wood had a higher degree of polymerization than the reference.
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| 9. |
- Bi, Ran, et al.
(author)
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Isolation and identification of microorganisms from soil able to ive on lignin as carbon source and produce enzymes that cleave beta-O-4mbond in lignin
- 2011
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In: Cellulose Chemistry and Technology. - 0576-9787.
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Journal article (peer-reviewed)abstract
- Twenty one strains of micro organism from Scandinavian soil had been isolated that could utilize lignin as only carbon source and 11 strains of them were identified. Different types of technical lignins were used.5 faster growing strains were cultivated in shaking flask cultures with ligninosulfonate as sole carbon source,and lignin appeared to be consumed after several days while mycelia was observed accumulated.Cell free filtrates of the 5 faster growing strains could lower the apparent molecular weights of lignosulphonates and the culture filtrate of one strain could cleave the lignin model compound with.The significances of the results are discussed.
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| 10. |
- Christiernin, Maria, et al.
(author)
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Analysis of lignin isolated from poplar cell suspension cultures
- 2005
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In: 59th Appita Annual Conference and Exhibition, incorporating the 13th ISWFPC. ; , s. 81-86
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Conference paper (peer-reviewed)abstract
- We have investigated lignin structures in pure primary cell walls. Poplar cell suspension cultures, Populus tremula x tremuloides, were harvested after 7, 14 and 21 days of growth. Carbohydrate monomer analysis also points at the presence of primary wall exclusively. Confocal microscopy of the cells dyed with acriflavin demonstrates that lignin is present. Klason content increases during growth from 0.7 to 3.9 percent. GC analysis of samples subjected to thioacidolysis shows that the lignin constitutes of guaiacyl units as compared to poplar wood which have syringyl as the main monomer. The amount of monomers per unit Klason lignin is lower than in wood and it decreases during cultivation possibly indicating a larger relative content of carbon-carbon bonds in the polymeric lignin in the cell cultures as compared to wood. Five lignin structures were identified with massspectrometry.
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