Characterization of a thermostable xylanase from an alkaliphilic Bacillus sp.
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A xylanase gene (xyn10) from alkaliphilic Bacillus sp. N16-5 was cloned and expressed in Pichia pastoris. The deduced amino acid sequence has 85% identity with xylanase xyn10A from B. halodurans and contains two potential N-glycosylation sites. The glycosylated Xyn10 with MW 48 kDa can hydrolyze birchwood and oatspelt xylan. The enzyme had optimum activity at pH 7 and 70°C, with the specific activity of 92.5U/mg. The Xyn10 retained over 90% residual activity at 60°C for 30 min but lost all activity at 80°C over 15 min. Most tested ions showed no or slight inhibition effects on enzyme activity.
KeywordsBacillus sp. Heterologous expression Pichia pastoris Thermostable xylanase
This study was supported by the Ministry of Sciences and Technology of China (973 programs 2007CB707801, 863 programs 2006AA020201 and 2007AA021306) and Hubei Province Nature Science Foundation (2008CDB058).
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