Effect of Culture Variables on Production of a Novel Xylanase by the Phytase-Producing Strain Aspergillus carneus M34 in Shake Flask Cultures

The effects of culture conditions on the production of a novel xylanase (group Ⅰ of family 11 endoxylanases) by Aspergillus carneus M34 in a submerged culture was performed using a filamentous fungus with phytase activity isolated from Taiwanese soil. Among the various carbon sources tested, birch wood xylan was the most effective carbohydrate for the formation of xylanase activities, followed by oat xylan. In addition, the fungus produced xylanase activity in the presence of a soluble carbon source, such as arabinose. No xylanolytic enzyme activity was detected when the organism was grown on dextrin. The highest xylanase activity was found in a medium containing peptone (5.8 mg N/liter) as the nitrogen source. The production of this novel enzyme was tolerant to a wide range of initial culture pH values, with pH 8.0 supporting the highest xylanase production. The optimum temperature and agitation rate for the microorganisms to produce xylanase were 40℃ and 130 rpm, respectively. Fermentation in shake flask cultures using the optimized medium with 15 g birch wood xylan/liter and peptone containing 5.8 mg N/liter, with fermentation conditions of initial pH of 8, a temperature of 40℃, and an agitation rate of 130 rpm, yielded 46.9 U/ml of xylanase and 650.7 (U/liter h) of xylanase productivity in 72 h. This crude enzyme showed a pH optimum of 7.0 and was stable in the range of pH 3.0 to 11.0. The optimum temperature of the crude xylanase was 50-60℃, with maximum thermal stability at 40℃.

並列關鍵字

Culture variables ； Aspergillus carneus M34 ； Xylanase ； Shake flask culture ； Submerged fermentation

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