The objective of this research was to investigate the influence of physicochemical
properties of lignocellulosic biomass on the rate and extent of cellulose conversion, i.e.
the "hydrolyzability" of the substrate.
The initial two parts of this thesis investigated the interactions between various
components of pretreated biomass. The relevance of cellulase partitioning between the
cellulose and non-cellulose components of pretreated switchgrass was determined.
Furthermore, a method was developed to assess the changes in surface area of the non-cellulose
fraction during saccharification. The overall conclusion from these studies was
that for an optimally pretreated switchgrass sample the cellulose and non-cellulose
components are fully disassociated and the non-cellulose fraction does not appear to
interfere with cellulose conversion.
The third study determined the changes in physicochemical properties of native
and pretreated poplar during simultaneous saccharification and fermentation (SSF).
While this study gave an unprecedented insight into the dynamics of SSF, it was also
apparent that parameters measuring the complete feedstock are inadequate for explaining
cellulose reactivity/hydrolyzability during saccharification.
As a consequence of these conclusions, the final study focused on properties of
model celluloses and initial rates of hydrolysis by the major cellulase - CBHI. The
content of insoluble ends was measured by different modified soluble reducing sugar
assays and by tritium labeling through NaB³H₄ reduction reactions. The content of
insoluble reducing ends partially explained the relative initial rates of hydrolysis. However, comparisons between celluloses in their crystalline and corresponding
amorphous state revealed that crystallinity also accounts for some of the observed rate
differences. Furthermore, surface characteristics, such as the presence of pores, must be
considered to fully explain cellulose reactivity. / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26187 |
| Date | 01 December 1998 |
| Creators | Meunier-Goddik, Lisbeth |
| Contributors | Penner, Michael H. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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