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Title: Thermostable and Alkaline xylanase from an alkaliphilic Actinomycete
Authors: Amare, Siraw
Keywords: Actinomycete
Date Added: 31-Aug-2007
Abstract: A xylanase producing alkaliphilic actinomycete strain designated AS-19 was isolated from Lake Abjata, an alkaline Soda Lake in Ethiopia. The strain produce xylanase in solid state fermentation (SSF) using different agricultural residues (wheat bran, sugarcane bagass, and saw dust) as substrates without enrichment of the medium .The highest level of enzyme was produced in wheat bran (165 U/g). Maximum production of xylanase was observed at wheat bran-tomoisturing agent ratio of 1:1.5(w/v) at 37 0C for 72 h. Birch wood xylan enhances enzyme production with 110 % while xylose, aribinose, glucose, lactose and fructose strongly repressed the enzyme production. In the presence of metal ions such as HgCl2, and, ZnSO4 the activity of the enzyme was strongly inhibited. Birch wood xylan was hydrolyzed more rapidly than oat spelt xylan. The optimum pH of the enzyme was 8.5-10 and stable at alkaline pH (8-10). The optimum temperature for enzyme activity was 70-80 0C at pH 9. The enzyme after 4 h incubation retained 77.7 and 54 % of its original activity at 75 and 80 0C respectively, at pH 9. The enzyme is also stable over wide temperature range (50-80 0C) for 1 h at pH 9. Thus, the result showed that the enzyme is both alkaline and thermostable. The enzymatic products of xylan hydrolysis were a series of short-chain xylooligsaccharides, indicating the enzyme was an endoxylanase. These are some characteristics that make this enzyme potentially very attractive for industrial applications.
Description: A Thesis submitted to the School of Graduate studies, Addis Ababa University in partial ful fillment of the requirement for the Degree of Masters of Science in Biology (Applied Microbiology)
URI: http://hdl.handle.net/123456789/27
Appears in:Thesis - Biology

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