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 amount 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).
- Research Organization:
- Dartmouth College, Hanover, NH
- OSTI ID:
- 6803615
- Journal Information:
- Biotechnol. Bioeng.; (United States), Vol. 29:1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
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
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