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Hemicelluloses from Agricultural and Forestry Crops Isolation, Characterisation, and Enzymatic Hydrolysis

Andersson, Alexandra LU (2007)
Abstract (Swedish)
Popular Abstract in Swedish

Hemicellulosa är en fantastisk källa av förnyelsebar råvara, vars användning har potental att bli kraftigt utökad i framtiden. Hemicellulosor är tillsammans, med lignin och cellulosa bland de mest förekommande klasserna av ämnen i växtcellernas väggar. Dessa tre beståndsdelar är tätt sammanlänkade, vilket gör det svårt att separera dem från varandra. Hemicellulosor är komplexa polysackarider och två stora klasser är heteroxylaner och heteromannaner.



I detta arbete har extraktion, isolering, karaktärisering, modifiering och enzymatisk hydrolys av hemicellulosor från lantbruks- och skogsråvara, undersökts. Extraktion av hemicellulosorna arabinoxylan från kornskal och majsfibrer... (More)
Popular Abstract in Swedish

Hemicellulosa är en fantastisk källa av förnyelsebar råvara, vars användning har potental att bli kraftigt utökad i framtiden. Hemicellulosor är tillsammans, med lignin och cellulosa bland de mest förekommande klasserna av ämnen i växtcellernas väggar. Dessa tre beståndsdelar är tätt sammanlänkade, vilket gör det svårt att separera dem från varandra. Hemicellulosor är komplexa polysackarider och två stora klasser är heteroxylaner och heteromannaner.



I detta arbete har extraktion, isolering, karaktärisering, modifiering och enzymatisk hydrolys av hemicellulosor från lantbruks- och skogsråvara, undersökts. Extraktion av hemicellulosorna arabinoxylan från kornskal och majsfibrer samt acetylerad galaktoglukomannan (AcGGM) från granflis utfördes med värmeextraktion vid neutrala förhållanden, med mikrovågsugn eller ångexplosion. Extraktion av polymera hemicellulosor var möjlig och de hemicellulosor som blivit extraherade vid neutrala förhållande var alla acetylerade. Isolering och koncentrering av de vattenlösliga hemicellulosorna utfördes med både membranfiltrering och gelfiltrering.



Glycosyl hydrolaser är viktiga verktyg för karakterisering och modifiering av hemicellulosornas egenskaper och struktur. Sidogruppernas betydelse för AcGGMs löslighet undersöktes med hjälp av ett a-galaktosidas och kemisk deacetylering med alkali. B-Mannanas-katalyserad hydrolys av AcGGM med olika grad av naturliga och kemiska substituenter avslöjade steriskt hinder och lägre hydrolyshastighet med ökad substituering. Hydrogeler skapades från kemiskt modifierad AcGGM. BSA inkorporerades som en modellsubstans. Frisläppningen av BSA från AcGGM-innehållande hydrogeler ökade med tillsats av b-mannanas.



En mannan-bindande moduls affinitet mot galaktomannan demonstrerades i ett två-fas system. En potentiell metod för initiell upprening av enzymer innehållande en kolhydratbindande modul har föreslagits.



Sammanfattningsvis har metoder för extraktion, vidare isolering med membranfiltrering, karaktärisering med gelfiltrering och enzymatisk hydrolys av hemicellulosor presenterats. Slutligen har ett exempel på användning av dessa hemicellulosor exemplifierats genom skapandet av hydrogeler. Detta arbete har bidragit med kunskap om hemicellulosornas kemi och förslag till framtida applikationer ämnade för ett mer miljömässigt hållbart samhälle. (Less)
Abstract
Hemicelluloses are tremendous sources of renewable raw materials, which utilisation have the potential to be highly increased in the future. Hemicelluloses are among the major groups of compounds in plant cell walls, together with cellulose and lignin. These three components are closely associated, making them difficult to separate from each other. Hemicelluloses are complex polysaccharides and two major classes are heteroxylans and heteromannans.



In this work, the extraction, isolation, characterisation, modification and enzymatic hydrolysis of hemicelluloses from agricultural and forestry crops have been investigated. Extraction of the hemicelluloses arabinoxylan from barley husks, and corn fibres and acetylated... (More)
Hemicelluloses are tremendous sources of renewable raw materials, which utilisation have the potential to be highly increased in the future. Hemicelluloses are among the major groups of compounds in plant cell walls, together with cellulose and lignin. These three components are closely associated, making them difficult to separate from each other. Hemicelluloses are complex polysaccharides and two major classes are heteroxylans and heteromannans.



In this work, the extraction, isolation, characterisation, modification and enzymatic hydrolysis of hemicelluloses from agricultural and forestry crops have been investigated. Extraction of the hemicelluloses arabinoxylan from barley husks, and corn fibres and acetylated galactoglucomannan (AcGGM) from spruce chips, was performed with heat treatment at neutral conditions, using microwave irradiation or steam pretreatment. Extraction of polymeric hemicelluloses was possible and the hemicelluloses extracted from all species investigated were acetylated. Isolation and concentration of the soluble hemicelluloses were performed with membrane filtration and size-exclusion chromatography (SEC), respectively.



Glycosyl hydrolases are important tools for the characterisation and modification of the properties and structure of hemicelluloses. The influence of side group substitution on AcGGM solubility was investigated using an a-galactosidase and chemical de-acetylation with alkali. B-mannanase catalysed hydrolysis of AcGGM with various degrees of natural and chemical substituents revealed steric hindrance and decreased hydrolysis rate with increased substitution. Hydrogels were made from chemically modified AcGGM. BSA was incorporated as a model drug. The release of BSA from AcGGM hydrolgels was increased by the addition of b-mannanase.



The affinity of a mannan-binding module to galactomannan was demonstrated in an aqueous two-phase system. A potential method for primary recovery of enzymes with the aid of a carbohydrate-binding module is suggested.



In conclusion, methods of extracting hemicelluloses are presented together with further isolation with membrane filtration, characterisation with SEC and enzymatic hydrolysis. Finally, an example of the utilisation of hemicelluloses is provided by creating hydrogels. This work has gained insight into the chemistry of hemicelluloses and suggestions for future applications aimed at a more sustainable society. (Less)
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author
supervisor
opponent
  • Associate Professor Schols, Henk, Wageningen University, The Netherlands
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Proteiner, enzymologi, Physical chemistry, Fysikalisk kemi, enzymology, hydrogels, Plant biochemistry, Växtbiokemi, Proteins, a-galactosidase, b-mannanase, hemicellulase, corn fibre, barley husks, spruce, size-exclusion chromatography, arabinoxylan, microwave irradiation, steam pretreatment, membrane filtration, hemicellulose, galactoglucomannan
pages
66 pages
publisher
Department of Biochemistry, Lund University
defense location
Hörsal B Kemicentrum Sölvegatan 39 Lund
defense date
2007-06-13 10:15
ISBN
978-91-7422-163-3
language
English
LU publication?
yes
id
58e0b431-21c5-4ef5-9942-8ef38a182906 (old id 548787)
date added to LUP
2007-10-09 09:28:38
date last changed
2016-09-19 08:45:09
@misc{58e0b431-21c5-4ef5-9942-8ef38a182906,
  abstract     = {Hemicelluloses are tremendous sources of renewable raw materials, which utilisation have the potential to be highly increased in the future. Hemicelluloses are among the major groups of compounds in plant cell walls, together with cellulose and lignin. These three components are closely associated, making them difficult to separate from each other. Hemicelluloses are complex polysaccharides and two major classes are heteroxylans and heteromannans.<br/><br>
<br/><br>
In this work, the extraction, isolation, characterisation, modification and enzymatic hydrolysis of hemicelluloses from agricultural and forestry crops have been investigated. Extraction of the hemicelluloses arabinoxylan from barley husks, and corn fibres and acetylated galactoglucomannan (AcGGM) from spruce chips, was performed with heat treatment at neutral conditions, using microwave irradiation or steam pretreatment. Extraction of polymeric hemicelluloses was possible and the hemicelluloses extracted from all species investigated were acetylated. Isolation and concentration of the soluble hemicelluloses were performed with membrane filtration and size-exclusion chromatography (SEC), respectively.<br/><br>
<br/><br>
Glycosyl hydrolases are important tools for the characterisation and modification of the properties and structure of hemicelluloses. The influence of side group substitution on AcGGM solubility was investigated using an a-galactosidase and chemical de-acetylation with alkali. B-mannanase catalysed hydrolysis of AcGGM with various degrees of natural and chemical substituents revealed steric hindrance and decreased hydrolysis rate with increased substitution. Hydrogels were made from chemically modified AcGGM. BSA was incorporated as a model drug. The release of BSA from AcGGM hydrolgels was increased by the addition of b-mannanase.<br/><br>
<br/><br>
The affinity of a mannan-binding module to galactomannan was demonstrated in an aqueous two-phase system. A potential method for primary recovery of enzymes with the aid of a carbohydrate-binding module is suggested.<br/><br>
<br/><br>
In conclusion, methods of extracting hemicelluloses are presented together with further isolation with membrane filtration, characterisation with SEC and enzymatic hydrolysis. Finally, an example of the utilisation of hemicelluloses is provided by creating hydrogels. This work has gained insight into the chemistry of hemicelluloses and suggestions for future applications aimed at a more sustainable society.},
  author       = {Andersson, Alexandra},
  isbn         = {978-91-7422-163-3},
  keyword      = {Proteiner,enzymologi,Physical chemistry,Fysikalisk kemi,enzymology,hydrogels,Plant biochemistry,Växtbiokemi,Proteins,a-galactosidase,b-mannanase,hemicellulase,corn fibre,barley husks,spruce,size-exclusion chromatography,arabinoxylan,microwave irradiation,steam pretreatment,membrane filtration,hemicellulose,galactoglucomannan},
  language     = {eng},
  pages        = {66},
  publisher    = {ARRAY(0x98a5e70)},
  title        = {Hemicelluloses from Agricultural and Forestry Crops Isolation, Characterisation, and Enzymatic Hydrolysis},
  year         = {2007},
}