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ARS Home » Research » Publications at this Location » Publication #65635
Title: GLUCOSE TOLERANT AND THERMOPHILIC BETA-GLUCOSIDASES FROM YEASTS

Author
item Saha, Badal
item Bothast, Rodney

Submitted to: Biotechnology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Agricultural residue, particularly corn fiber, is available in sufficient quantities from the corn wet milling industry to serve as a low cost feedstock for production of fuel alcohol. Industrial enzyme technology for conversion of fiber to fermentable sugars must be improved in order to lower the cost of fuel production from fiber. One particular enzyme is sensitive to the simple sugar, glucose, and high temperatures and controls fiber breakdown. We screened 48 yeast strains (obtained from the ARS (NRRL) Culture Collection, Peoria, IL) for production of glucose and a high temperature tolerant enzyme. Enzymes from 15 yeast strains showed very high glucose tolerance. Novel glucose tolerance and activity at high temperature found in three yeast enzyme preparations are desired attributes suitable for industrial application.

Technical Abstract: The enzyme, beta-glucosidase, is sensitive to glucose and high temperatures and is rate limiting during enzymatic hydrolysis of cellulose to glucose. Forty-eight yeast strains belonging to the genera Candida, Debaryomyces, Kluyveromyces and Pichia (obtained from the ARS Culture Collection, Peoria, IL) were screened for production of extracellular glucose tolerant and thermophilic beta-glucosidase activity using p-nitrophenyl-beta-D-glucosidase as substrate. Enzymes from 15 yeast strains showed very high glucose tolerance (<50% inhibition at 30%, w/v glucose). The optimal temperatures and pH for these beta-glucosidase activities varied from 30 to 65 deg C and pH 4.5 to 6.5. The beta-glucosidases from all these yeast strains hydrolyzed cellobiose.