Akhavan Sepahy Abbas, Ghazi Shokoofeh, Akhavan Sepahy Maryam
Department of Microbiology, Faculty of Basic Sciences, Islamic Azad University, 16 South Makran St., Heravi Sq., Pasdaran, Tehran 19585, Iran.
Enzyme Res. 2011;2011:593624. doi: 10.4061/2011/593624. Epub 2011 Aug 29.
A xylanase producer Bacillus mojavensis strain, called AG137, isolated from cotton farm (Kashan-Iran). The optimal xylanase activity reached at 55°C & pH 9.0. Enzyme yield was studied using a medium with different agricultural wastes as inducers. Xylanase production of about 249.308 IU/mL was achieved at pH 8 and 37°C, within 48 h submerged fermentation in enzyme production medium supplemented with 2% (w/v) oat bran as an optimum carbon source. A mixture of 1% (w/v) yeast extract and 1% (w/v) tryptone as optimum nitrogen sources, agitation speed 200 rpm, and inoculum size 2% (v/v) were the optimums for maximum production. Accordingly, xylanase yield from 194.68 IU/mL under non-optimized fermentation condition enhanced to 302.466 IU/mL in optimized condition. Screened xylanase is thermostable, presenting 70% stability at 60°C during 30 min. Further enzyme incubation in higher temperature caused a decrease in the residual enzyme activity, yet it retained 68%-50% of its activity after 1 hour from 45°C to 55°C. Besides, it is stable in pH 9 and 10, maintaining over 70% of its activity for 2 h. The enzyme also could preserve 71% and 63% of its initial activity after 3 hours of pre-incubation in the same alkaline condition. Produced xylanase therefore was introduced as an alkaline-active and stable one, displaying suitable thermostability feature, confirmed by HPLC analysis. Hence, all xylanase properties highlight its promising uses in industrial scale.
从棉花农场（伊朗卡尚）分离出的一株木聚糖酶产生菌莫哈韦芽孢杆菌菌株AG137。木聚糖酶的最佳活性在55°C和pH 9.0时达到。使用含有不同农业废弃物作为诱导剂的培养基研究了酶产量。在pH 8和37°C条件下，以2%（w/v）燕麦麸作为最佳碳源，在酶生产培养基中进行48小时的深层发酵，木聚糖酶产量达到约249.308 IU/mL。1%（w/v）酵母提取物和1%（w/v）胰蛋白胨的混合物作为最佳氮源、搅拌速度200 rpm以及接种量2%（v/v）是最大产量的最佳条件。因此，在非优化发酵条件下木聚糖酶产量从194.68 IU/mL提高到优化条件下的302.466 IU/mL。筛选出的木聚糖酶具有热稳定性，可以在60°C下保持30分钟70%的稳定性。在更高温度下进一步孵育酶会导致残余酶活性降低，但在45°C至55°C下1小时后仍保留其68%-50%的活性。此外，它在pH 9和10时稳定，在2小时内保持超过70%的活性。在相同碱性条件下预孵育3小时后，该酶也能保留其初始活性的71%和63%。因此，所产生的木聚糖酶被认为是一种碱性活性且稳定的酶，具有合适的热稳定性特征，这通过高效液相色谱分析得到证实。因此，所有木聚糖酶的特性都突出了其在工业规模上的广阔应用前景。
