Institute of Animal Nutrition, Sichuan Agricultural University, Yaan, Sichuan 625014, China.
Br J Nutr. 2010 May;103(10):1507-13. doi: 10.1017/S0007114509993333. Epub 2010 Jan 12.
The xyn2 gene of a filamentous mesophilic fungus, Trichoderma reesei, coding xylanase 2 (Xyn2) was previously expressed in Pichia pastoris. In the present study, the recombinant Xyn2 was prepared from a 15 litre fermenter, and subsequently characterised. It has been confirmed to have a molecular mass of 21 kDa, an optimal pH of 6.0 and an optimal temperature of 60 degrees C. When tested using oat-spelt xylan, it showed a Km and catalytic rate constant (kcat) of 1.1 mg/ml and 512.4/s, respectively. Analysis of the products from oat-spelt xylan degradation confirmed that the enzyme was an endoxylanase with xylotriose and xylobiose as the main degradation products. The unprocessed Xyn2 was supplemented to a xylan-containing diet to determine its influences on performance and nutrient digestibilities by weaned pigs. Results showed that the average body-weight gain increased 16.9 % when piglets received Xyn2 at a concentration of 500 U/kg diet. There also was a positive (0.05 < P < 0.10) effect on the digestibility values of crude protein, ash, Ca and acid-detergent fibre with Xyn2 supplementation. The potential benefits of Xyn2 in the nutrition of weaned pigs should make it an alternative applicant for industrial xylanase production.
先前曾在毕赤酵母中表达丝状嗜温真菌里氏木霉的 xyn2 基因，该基因编码木聚糖酶 2（Xyn2）。在本研究中，从 15 升发酵罐中制备重组 Xyn2，随后对其进行了特性分析。已证实其分子量为 21 kDa，最适 pH 值为 6.0，最适温度为 60°C。当用燕麦-斯佩尔特木聚糖进行测试时，其 Km 和催化速率常数（kcat）分别为 1.1 mg/ml 和 512.4/s。对燕麦-斯佩尔特木聚糖降解产物的分析证实，该酶是一种内切木聚糖酶，主要降解产物为木三糖和木二糖。未加工的 Xyn2 被添加到含木聚糖的饮食中，以确定其对断奶仔猪性能和养分消化率的影响。结果表明，当仔猪日粮中添加 500 U/kg 的 Xyn2 时，平均体重增加了 16.9%。Xyn2 补充剂对粗蛋白、灰分、Ca 和酸性洗涤剂纤维的消化率值也有积极影响（0.05 < P < 0.10）。Xyn2 在断奶仔猪营养中的潜在益处使其成为工业木聚糖酶生产的替代候选者。
