Abstract

A xylanase producing bacterium was isolated from paper mill sludge in Thunder Bay, Canada. The newly isolated bacterium was identified as Pseudomonas boreopolis according to its 16S rRNA gene sequence and designated as LUQ1. The zymogram analysis indicated that there was one band of protein with xylanase activity, and the molecular weight of the enzyme was about 20 kDa. This xylanase works best at pH 6.0 and 65°C. The xylanase can be induced to express by xylose. The expression was enhanced on increasing the concentration of xylose, which reached its highest activity at 12 mM of xylose in fermentation. Wheat bran was the best carbon source in submerged fermentation. The highest xylanase activity of 25.61 U/ml was obtained at 96 h using wheat bran feedstock. When barley straw and wheat bran were used as feedstocks, the addition of 10 mM of xylose increased xylanase activity by ~50% and ~15%, respectively. The results showed that the strain LUQ1 has a great potential to produce xylanase for industrial applications.

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