OXIDATIVE PRETREATMENT OF SPRUCE TO FACILITATE ENZYMATIC HYDROLYSIS OF POLYSACCHARIDES

OXIDATIVE PRETREATMENT OF SPRUCE TO FACILITATE ENZYMATIC HYDROLYSIS OF POLYSACCHARIDES

By Dylan Montgomery

Thesis Advisors: Dr. Barbara J. W. Cole and Dr. Raymond C. Fort, Jr.

A Lay Abstract of the Thesis Presented

in Partial Fulfillment of the Requirements for the

Degree of Master of Science

(in Chemistry)

May, 2010

Brown rot fungi are wood-decaying organisms that degrade wood polysaccharides, the chains of sugar units that act as structural components in wood cell walls. The fungi accomplish this degradation with Fenton oxidation, a chemical reaction between ferrous iron and hydrogen peroxide. This oxidative system degrades the structural components of wood, allowing the brown rot fungi to cleave the sugar chains with hydrolytic enzymes. In an attempt to facilitate the isolation of simple sugar solutions from wood by treatment with commercial polysaccharide-cleaving enzymes, spruce pin chips and wood meal were treated with three oxidative pretreatments. The primary objective was to partially degrade the wood cell wall and increase the accessibility of the polysaccharides to the enzymes. The treatments consisted of autoxidation (oxidation by molecular oxygen), Fenton oxidation, and the strong oxidant peracetic acid (PAA). The results of the pretreatments were analyzed by incubating the treated wood samples with the commercial cellulose-cleaving enzyme preparation Cellulysin and determining the amount of the cellulose unit glucose released by the enzyme. Glucose content was determined with high pH anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD), a technique that separates sugars in a resin-filled column and then detects them with an electrochemical reaction at a gold electrode. The autoxidation and Fenton oxidation pretreatments did not significantly increase the glucose yield, while PAA treatment afforded a slight increase in the amount of released glucose. Chemical compounds resulting from degradation of the wood component lignin were extracted from the reaction product solutions and analyzed with chromatography-mass spectrometry (GC-MS). This technique separates and identifies organic compounds. The compounds vanillin and vanillic acid were identified as the predominant products. GC-MS analysis of extracts of the autoxidation and Fenton oxidation product solutions yielded only trace amounts of vanillin. Attempts to detect the lignin degradation product methanol in the oxidation product solutions yielded negative results.