Comparison of extracellular cellulase activities of ClosTridium thermocellum LQRI and trichoderma reesei QM9414

Journal Article · Sat Aug 01 04:00:00 EDT 1981 · Appl. Environ. Microbiol.; (United States)

OSTI ID:5110815

Ng, T K; Zeikus, J G

The crude extracellular cellulase of Clostridium thermocellum LQRI (virgin strain) was very active and solubilized microcrystalline cellulose at one-half the rate observed for the extracellular cellulase of Trichoderma reesei QM9414 (mutant strain). Clostridium thermocellum cellulase activity differed considerably from that of Trichoderma reesei as follows: higher endoglucanase/exoglucanase activity ratio; absence of extracellular cellobiase or beta-xylosidase activity; long-chain oligosaccharides instead of short-chain oligosaccharides as initial (15-min) hydrolytic products on microcrystalline cellulose; mainly cellobiose or xylobiose as long-term (24-h) hydrolysis products of Avicel and MN300 or xylan; and high activity and stability at 60 to 70 degrees Celcius. Under optimized reaction conditions, the kinetic properties (V max, 0.4 mu mol/min per mg of protein; energy of activation, 33 kJ; temperature coefficient, 1.8) of Clostridium thermocellum cellulose-solubilizing activity were comparable to those reported for Trichoderma reesei, except that the dyed Avicel concentration at half-maximal velocity was twofold higher (182 mu M). The cellulose-solubilizing activity of the two crude cellulases differed considerably in response to various enzyme inhibitors. Most notably, Ag/sup 2 +/ and Hg/sup 2 +/ effectively inhibited Clostridium thermocellum but not Trichoderma reesei cellulase at less than 20 mu M, whereas Ca/sup 2 +/, Mg/sup 2 +/, and Mn/sup 2 +/ inhibited Trichoderma reesei but not Clostridium thermocellum cellulase at greater than 10 mM. Both enzymes were inhibited by Cu/sup 2 +/ (greater than 20 mM), Zn2+ (greater than 10 mM), and ethylene glycol-bis (beta-aminoethyl ether)-N, N-tetraacetic acid (greater than 10 mM). The overal rates of cellooligosaccharide degradation were higher for Trichoderma reesei than for Clostridium thermocellum cellulase, except that the rates of conversion of cellohexaose to cellotrisse were equivalent.

• Research Organization: Dept. of Bacteriology, Univ. of Wisconsin-Madison, Madison
• OSTI ID: 5110815
• Journal Information: Appl. Environ. Microbiol.; (United States), Journal Name: Appl. Environ. Microbiol.; (United States) Vol. 42:2; ISSN AEMID
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
BACTERIA
BIOSYNTHESIS
CARBOHYDRATES
CELLULASE
CELLULOLYTIC ACTIVITY
CELLULOSE
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CLOSTRIDIUM
CLOSTRIDIUM THERMOCELLUM
COMPARATIVE EVALUATIONS
DECOMPOSITION
ENZYME ACTIVITY
ENZYMES
FUNGI
GLYCOSYL HYDROLASES
HYDROLASES
HYDROLYSIS
INHIBITION
KINETICS
LYSIS
MICROORGANISMS
O-GLYCOSYL HYDROLASES
ORGANIC COMPOUNDS
PLANTS
POLYSACCHARIDES
REACTION KINETICS
SACCHARIDES
SACCHARIFICATION
SOLVOLYSIS
SYNTHESIS
TRICHODERMA
TRICHODERMA VIRIDE