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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/69

Title: Xylanase and Cellulase production by a termite associated Xylaria species
Authors: Tulu, Degefu
Keywords: Xylaria
Xylanase
cellulase
Termites
Date Added: 4-Sep-2007
Abstract: Xylaria sp. are known to be associated with termites. However, the benefit the termites get from this association is not yet known. Termites collect wood pieces from the surrounding and collect it in the mound. The wood is then converted to soft spongy mass, called comb. The comb is normally invaded with fungal mycelia. It is well known that termites use cellulose as energy source after degradation to glucose with the help of microbial celluloses in the gut. But lignified celluloses cannot be digested by cellulases. We hypothesize that the fungus probably helps to delignify cellulose fiber either directly though lignin degradation or through removal of the hemi cellulose that cement the lignin to the cellulose fiber. To test this hypothesis we collected termite comb from Zuway and extracted proteins. The extract showed high xylanase activity (24U/g comb) and no detectable cellulose activity. This indicates that the role of the fungus is probably to remove lignin from the cellulose fiber. The fact that there was no detectable cellulose in the comb indicates that the fungus and the termite are not competing for cellulose. The fungus was isolated from the comb in pure culture. It was then grown in culture using submerged fermentation (SmF) and solid-state fermentation (SSF). However enzyme production in SSF was much higher than in SmF. Maximum enzyme production in SSF using wheat bran was obtained at a substrate to moisture level ration of 1:0.5 to 1:2 addition of different sugars to the SSF substrate didn’t affect enzyme production, indicating that enzyme production is probably constitutive. The xylanase was optimally active in the pH range of 4 to 6 and at temperature of 40-degree cent. These properties make Xylaria xylanase potentially attractive as animal feed supplements.
Description: A Thesis submitted to school of graduate studies of Addis Ababa University in partial fulfillment of the degree of masters in Biology (Applied Mivrobiology).
URI: http://hdl.handle.net/123456789/69
Appears in:Thesis - Biology

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