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dc.creatorZeng, Jijiao
dc.date.accessioned2013-09-19T18:43:46Z
dc.date.available2013-09-19T18:43:46Z
dc.date.issued2012
dc.identifier.urihttp://hdl.handle.net/2376/4693
dc.descriptionThesis (Ph.D.), Washington State Universityen_US
dc.description.abstractThe main aim of this dissertation research was to understand the natural microbial degradation process of lignocellulosic materials in order to develop a new, green and more effective pretreatment technology for bio-fuel production. The biodegradation of wheat straw by white rot fungi Phanerochaete chrysosporium was investigated. The addition of nutrients significantly improved the performance of P.chrysosporium on wheat straw degradation. The proteomic analysis indicated that this fungus produced various pepetides related to cellulose and lignin degradation while grown on the biomass. The structural analysis of lignin further showed that P.chrysosporium preferentially degraded hydroxycinnamtes in order to access cellulose. In details, the effects of carbon resource and metabolic pathway regulating compounds on manganeses peroxidase (MnP) were studied. The results indicated that MnP activity of 4.7 ± 0.31 U mL-1 was obtained using mannose as a carbon source. The enzyme productivity further reached 7.36 ± 0.05 U mL-1 and 8.77 ± 0.23 U mL-1 when the mannose medium was supplemented with cyclic adenosine monophosphate (cAMP) and S-adenosylmethionine (SAM) respectively, revealing highest MnP productivity obtained by optimizing the carbon sources and supplementation with small molecules. In addition, the effects of nutrient additives for improving biological pretreatment of lignocellulosic biomass were studied. The pretreatment of wheat straw supplemented with inorganic salts (salts group) and tween 80 was examined. The extra nutrient significantly improved the ligninase expression leading to improve digestibility of lignocellulosic biomass. Among the solid state fermentation groups, salts group resulted in a substantial degradation of wheat straw within one week, along with the highest lignin loss (25 %) and ~ 250% higher efficiency for the total sugar release through enzymatic hydrolysis. The results were correlated with pyrolysis GC-MS (Py-GC-MS), thermogravimetric (TG) /differential thermogravimetric (DTG) and X-ray diffraction (XRD). Finally, the fungal secretomes and composition, functional groups, and structural changes of the fungal spent wheat straw lignin were determined.Milled wood lignin (MWL) was extracted from biological treated and untreaed wheat straw. Detailed structural analysis through two dimentional heteronuclear multiple quantum coherence nuclear magnetic resonances (2D HMQC NMR) of the pretreated lignin (acetylated) revealed low abundances of the substructures dibenzodioxacin and cinnamyl alcohol. Further analysis of lignin by Fourier transmission infrared (FTIR) and pyrolysis gas chromatography/ mass spectrometry (Py-GC/MS) demonstrated the significant decrease of guaiacyl units. The results support previous findings on the biodegradation of wheat straw as analyzed by 13C cross polarization magic angle spinning (CPMAS). Revealing the characteristic behavior of P. chrysosporium-mediated biomass degradation, the information presented in this paper offers new insight into the understanding of biological lignin degradation of wheat straw by P. chrysosporium.en_US
dc.description.sponsorshipDepartment of Biological and Agricultural Engineering, Washington State Universityen_US
dc.language.isoEnglish
dc.rightsIn copyright
dc.rightsNot publicly accessible
dc.rightsclosedAccess
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.rights.urihttp://www.ndltd.org/standards/metadata
dc.rights.urihttp://purl.org/eprint/accessRights/ClosedAccess
dc.subjectEngineeringen_US
dc.subjectEnergyen_US
dc.subjectEnvironmental engineeringen_US
dc.subjectBio-degradationen_US
dc.subjectCellulose hydrolysisen_US
dc.subjectherbaceous cropsen_US
dc.subjectLigninen_US
dc.subjectLigninaseen_US
dc.subjectNMRen_US
dc.titleDEGRADATION OF WHEAT STRAW CELL WALL BY WHITE ROT FUNGI PHANEROCHAETE CHRYSOSPORIUM
dc.typeElectronic Thesis or Dissertation


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