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Title: Hydrolysis of dilute acid pretreated mixed hardwood and purified microcrystalline cellulose by cell-free broth from Clostridium thermocellum

The cellulase activity in cell-free broths from Clostridium thermocellum is examined on both dilute-acid-pretreated mixed hardwood (90% maple, 10% birch) and Avicel. Experiments were conducted in vitro in order to distinguish properties of the cellulase from properties of the organism and to evaluate the effectiveness of C. thermocellum cellulase in the hydrolysis of a naturally occurring, lignin-containing substrate. The results obtained establish that essentially quantitative hydrolysis of cellulose from pretreated mixed hardwood is possible using this enzyme system. Pretreatment with 1% H/sub 2/SO/sub 4/ and a 9-s residence time at 220, 210, 200, and 180/sup 0/C allowed yields after enzymatic hydrolysis (percentage of glucan solubilized/glucan potentially solubilized) of 97.8, 86.1, 82.0, and 34.6%, respectively. Enzymatic hydrolysis of mixed hardwood with no pretreatment resulted in a yield of 10.1%. Hydrolysis yields of greater than 95% were obtained from 0.6 g/l mixed hardwood pretreated at 220/sup 0/C in 7 hours at broth strengths of 60 and 80% (v/v) and in approximately 48 hours with 33% broth. Hydrolysis of pretreated mixed hardwood is compared to hydrolysis of Avicel. The initial rate of Avicel hydrolysis saturates with respect to enzyme, whereas the initial rate of hydrolysis of pretreated wood is proportional to the amountmore » of enzyme present. Initial hydrolysis rates for pretreated wood and Avicel at 0.6 g/l are greater for wood at low broth dilutions (1.25:1 to 5:1) by up to 2.7-fold and greater for Avicel at high broth dilutions (5:1 to 50:1) by up to 4.3-fold. Maximum rates of hydrolysis are achieved at less than 2 g substrate/liter for both pretreated wood and Avicel).« less
Authors:
;
Publication Date:
OSTI Identifier:
6803615
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biotechnol. Bioeng.; (United States); Journal Volume: 29:1
Research Org:
Dartmouth College, Hanover, NH
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; CELLULOSE; ACID HYDROLYSIS; ENZYMATIC HYDROLYSIS; WOOD; CELLULASE; CLOSTRIDIUM THERMOCELLUM; ENZYME ACTIVITY; ETHANOL; IN VITRO; LIGNIN; QUANTITY RATIO; SUBSTRATES; SULFURIC ACID; THERMOPHILIC CONDITIONS; ALCOHOLS; BACTERIA; CARBOHYDRATES; CHEMICAL REACTIONS; CLOSTRIDIUM; DECOMPOSITION; ENZYMES; GLYCOSYL HYDROLASES; HYDROGEN COMPOUNDS; HYDROLASES; HYDROLYSIS; HYDROXY COMPOUNDS; INORGANIC ACIDS; LYSIS; MICROORGANISMS; O-GLYCOSYL HYDROLASES; ORGANIC COMPOUNDS; POLYSACCHARIDES; SACCHARIDES; SOLVOLYSIS 090222* -- Alcohol Fuels-- Preparation from Wastes or Biomass-- (1976-1989); 140504 -- Solar Energy Conversion-- Biomass Production & Conversion-- (-1989)