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Lignocellulose Degradation by Soil Micro-organisms
KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Träkemi och massateknologi. KTH, Skolan för kemivetenskap (CHE), Centra, Wallenberg Wood Science Center.ORCID-id: 0000-0001-8135-588X
2016 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Lignocellulosic biomass is a sustainable resource with abundant reserves. Compared to petroleum ‐ based products, the biomass ‐ derived polymers and chemicals give better environmental profiles. A lot of research interest is focused on understanding the lignocellulose structures.

Lignin, among the three major wood components, represents most difficulty for microbial degradation because of its complex structure and because cross ‐ linking to hemicellulose makes wood such a compact structure. Nevertheless, wood is naturally degraded by wood ‐ degrading micro ‐ organisms and modified and partly degraded residual of lignin goes into soil. Therefore soil serves as a good environment in which to search for special lignin ‐ degraders. In this thesis, different types of lignin have been used as sole carbon sources to screen for lignin ‐ degrading soil micro ‐ organisms. Eleven aerobic and three anaerobic microbe strains have been isolated and identified as able to grow on lignin. The lignin degradation patterns of selected strains have been studied and these partly include an endwise cleavage of  β‐ O ‐ 4 bonds in lignin and is more complex than simple hydrolytic degradation.

As lignin exists in wood covalently bonded to hemicellulose, one isolated microbe strain, Phoma herbarum, has also been studied with regards to its ability to degrade covalent lignin polysaccharide networks (LCC). The results show that its culture filtrate can attack lignin ‐ polysaccharide networks in a manner different from that of the commercial enzyme product, Gammanase, possibly by selective cleavage of phenyl glucoside bonds. The effects on LCC of Phoma herbarum also enhance polymer extractability. Hot ‐ water extraction of a culture filtrate of Phoma herbarum ‐ treated fiberized spruce wood material gave an amount of extracted galactoglucomannan more than that given by the Gammanase ‐ treated material and non ‐ enzyme ‐ treated material.

Over millions of years of natural evolution, micro ‐ organisms on the one hand develop so that they can degrade all wood components to get energy for growth, while plants on the other hand also continuously develop to defend from microbial attack. Compared with lignin and cellulose, hemicelluloses as major components of plant cell walls, are much more easily degraded, but hemicelluloses differ from cellulose in that they are acetylated to different extents. The biological functions of acetylation are not completely understood, but it is suggested is that one function is to decrease the microbial degradability of cell walls. By cultivation of soil micro ‐ organisms using mannans acetylated to deffernent degrees as sole carbon source on agar plates, we were able to see significant trends where the resistance towards microbial degradation of glucomannan and galactomannan increased with increasing degree of acetylation. Possible mechanisms and the technological significance of this are discussed. Tailoring the degree of acetylation of polysaccharide materials might slow down the biodegradation, making it possible to design a material with a degradation rate suited to its application.

sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2016. , s. 59
Serie
TRITA-CHE-Report, ISSN 1654-1081 ; 2016:10
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-182336ISBN: 978-91-7595-868-2 (tryckt)OAI: oai:DiVA.org:kth-182336DiVA, id: diva2:904230
Disputas
2016-03-18, Kollegiesalen, Brinellvägen 8, KTH, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Forskningsfinansiär
Knut and Alice Wallenberg Foundation
Merknad

QC 20160223

Tilgjengelig fra: 2016-02-23 Laget: 2016-02-18 Sist oppdatert: 2017-03-02bibliografisk kontrollert
Delarbeid
1. Isolation and identification of microorganisms from soil able to live on lignin as a carbon source and to produce enzymes which cleave beta-O-4 bond in a lignin model compound
Åpne denne publikasjonen i ny fane eller vindu >>Isolation and identification of microorganisms from soil able to live on lignin as a carbon source and to produce enzymes which cleave beta-O-4 bond in a lignin model compound
Vise andre…
2012 (engelsk)Inngår i: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 46, nr 3-4, s. 227-242Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Several strains of fungi were isolated and identified from Scandinavian soil using agar plates with lignin as a carbon source. The strains grew significantly faster on this medium than on control plates without lignin. Different types of technical lignins were used, some of which contained trace amounts of sugars, even if the increased growth rate seemed not related to the sugar content. Some strains were cultivated in shaking flask cultures with lignin as a carbon source, with lignin apparently consumed by microbes - while accumulation of the microorganism biomass occurred. The cell-free filtrates of these cultures could reduce the apparent molecular weights of lignosulphonates, while the culture filtrate of one strain could cleave the beta-O-4 bond in a lignin model compound.

Emneord
lignin biodegradation, carbon source, soil microorganisms, extracellular enzymes, beta-O-4 bond
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-101134 (URN)000306779000010 ()2-s2.0-84864568077 (Scopus ID)
Merknad

QC 20120824

Tilgjengelig fra: 2012-08-24 Laget: 2012-08-23 Sist oppdatert: 2017-12-07bibliografisk kontrollert
2. Isolation of exceedingly low oxygen consuming fungal strains able to utilize lignin as carbon source
Åpne denne publikasjonen i ny fane eller vindu >>Isolation of exceedingly low oxygen consuming fungal strains able to utilize lignin as carbon source
(engelsk)Inngår i: Cellulose Chemistry and Technology, ISSN 0576-9787Artikkel i tidsskrift (Fagfellevurdert) Accepted
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-182253 (URN)
Merknad

QS 2016

Tilgjengelig fra: 2016-02-18 Laget: 2016-02-18 Sist oppdatert: 2017-11-30bibliografisk kontrollert
3. Phoma herbarum, a soil fungus able to grow on natural lignin and synthetic lignin (DHP) as sole carbon source and cause lignin degradation
Åpne denne publikasjonen i ny fane eller vindu >>Phoma herbarum, a soil fungus able to grow on natural lignin and synthetic lignin (DHP) as sole carbon source and cause lignin degradation
(engelsk)Manuskript (preprint) (Annet vitenskapelig)
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-182261 (URN)10.1007/s10295-016-1783-1 (DOI)
Merknad

QC 20160818

Tilgjengelig fra: 2016-02-18 Laget: 2016-02-18 Sist oppdatert: 2016-11-01bibliografisk kontrollert
4.
Posten ble ikke funnet. Det kan skyldes at posten ikke lenger er tilgjengelig eller det er feil id i adressefeltet.
5. Culture Filtrates from a Soil Organism Enhances Extractability of Polymers from Fiberised Spruce Wood
Åpne denne publikasjonen i ny fane eller vindu >>Culture Filtrates from a Soil Organism Enhances Extractability of Polymers from Fiberised Spruce Wood
(engelsk)Manuskript (preprint) (Annet vitenskapelig)
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-182279 (URN)
Merknad

QS 2016

Tilgjengelig fra: 2016-02-18 Laget: 2016-02-18 Sist oppdatert: 2016-02-23bibliografisk kontrollert
6. The Degree Of Acetylation Affects The Microbial Degradability Of Hemicelluloses
Åpne denne publikasjonen i ny fane eller vindu >>The Degree Of Acetylation Affects The Microbial Degradability Of Hemicelluloses
Vise andre…
(engelsk)Manuskript (preprint) (Annet vitenskapelig)
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-182286 (URN)
Merknad

QS 2016

Tilgjengelig fra: 2016-02-18 Laget: 2016-02-18 Sist oppdatert: 2016-02-23bibliografisk kontrollert

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