Xylanolytic activity of Clostridium acetobutylicum
Of 20 strains of Clostridium spp. screened, 17 hydrolyzed larch wood xylan. Two strains of Clostridium acetobutylicum, NRRL B527 and ATCC 824, hydrolyzed xylan but failed to grow on solid media with larch xylan as the sole carbon source; however, strain ATCC 824 was subsequently found to grow on xylan under specified conditions in a chemostat. These two strains possessed cellulolytic activity and were therefore selected for further studies. In cellobiose-limited continuous cultures, strain NRRL B527 produced maximum xylanase activity at pH 5.2. Strain ATCC 824 produced higher xylanase, xylopyranosidase, and arabinofuranosidase activities in chemostat culture with xylose than with any other soluble carbon source as the limiting nutrient. The activities of these enzymes were markedly reduced when the cells were grown in the presence of excess glucose. The xylanase showed maximum activity at pH 5.8 to 6.0 and 65/sup 0/C. The enzyme was stable on the alkaline side of pH 5.2 but was unstable below this pH value. The extracellular xylanolytic activity from strain ATCC 824 hydrolyzed 12% of the larch wood xylan during a 24-h incubation period, yielding xylose, xylobiose, and xylotriose as the major hydrolysis products. Strain ATCC 824, after being induced to grow in batch culture in xylan medium supplemented with a low concentration of xylose, failed to grow reproducibility in unsupplemented xylan medium. A mutant obtained by mutagenesis with ethyl methanosulfonate was able to grow reproducibility in batch culture on xylan. Both the parent strain and the mutant were able to grow with xylan as the sole source of carbohydrate in continuous culture with the pH maintained at either 5.2 or 6.0. Under these conditions, the cells utilized approximately 50% of the xylan.
- Research Organization:
- Univ. of Guelph, Ontario
- OSTI ID:
- 5619345
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Vol. 50:4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
CLOSTRIDIUM ACETOBUTYLICUM
CELLULOLYTIC ACTIVITY
XYLANS
ENZYMATIC HYDROLYSIS
CONTINUOUS CULTURE
GROWTH
NUTRIENTS
BACTERIA
CARBOHYDRATES
CHEMICAL REACTIONS
CLOSTRIDIUM
DECOMPOSITION
ENZYME ACTIVITY
HEMICELLULOSE
HYDROLYSIS
LYSIS
METHANOGENIC BACTERIA
MICROORGANISMS
ORGANIC COMPOUNDS
POLYSACCHARIDES
SACCHARIDES
SOLVOLYSIS
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