Bacterial strain Bacillus tequilensis BT21 isolated from marine sediments was found to produce extracellular xylanase. The xynBT21 gene encoding xylanase enzyme was cloned and expressed in Escherichia coli. The gene encoded a protein consisting of 213 amino acid residues with calculated molecular mass of 23.3 kDa. Purified recombinant xylanase had optimum activity at 60 °C and pH=6. The enzyme was highly stable in alkaline pH, at pH=7 it remained 100% active for 24 h, while its activity increased at pH=8 and 9 during incubation. B. tequilensis BT21 xylanase had alkaline pI of 9.4 and belongs to glycosyl hydrolase family 11. The mode of action of XynBT21 on beechwood xylan and xylooligosaccharides was studied. It hydrolysed xylooligosaccharides and beechwood xylan yielding mainly xylobiose (X₂) with a small amount of xylose (X₁), indicating that XynBT21 was probably an endo-acting xylanase. Enzymatic hydrolysis using wheat bran as a substrate revealed that xylanase reported here has the potential to produce xylobiose from wheat bran. Xylooligosaccharides, especially xylobiose, have strong bifidogenic properties and are increasingly used as a prebiotic. This is the first report that describes this novel xylanase enzyme from marine B. tequilensis BT21 used for the release of xylobiose from wheat bran.

中文翻译：

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芽孢杆菌BT21的重组木聚糖酶：生化特性及其在农业残留物中生产木糖的应用。

从海洋沉积物中分离出的细菌菌株tequilensis BT21被发现产生细胞外木聚糖酶。克隆了编码木聚糖酶的xynBT21基因，并在大肠杆菌中表达。该基因编码的蛋白质由213个氨基酸残基组成，计算的分子量为23.3 kDa。纯化的重组木聚糖酶在60°C和pH = 6时具有最佳活性。该酶在碱性pH值下非常稳定，在pH = 7的条件下在24小时内保持100％的活性，而在温育过程中在pH = 8和9时其活性增加。龙舌兰BT21木聚糖酶的碱性pI为9.4，属于糖基水解酶家族11。研究了XynBT21对山毛榉木聚糖和木寡糖的作用方式。它水解了木寡糖和山毛榉木聚糖，主要产生木糖（X ₂）和少量木糖（X ₁），这表明XynBT21可能是一种内在作用的木聚糖酶。使用麦麸作为底物的酶促水解显示，此处报道的木聚糖酶具有从麦麸生产木糖的潜力。低聚木糖，尤其是木糖，具有很强的双歧化特性，并越来越多地用作益生元。这是第一个描述这种新型木聚糖酶的酶的报道，该酶是从海洋B. tequilensis BT21中用于从麦麸中释放木糖的。