酵母β-葡聚糖水解酶的表达及应用

Expression and Application of Yeast β-Glucanase

摘要:

酵母β-葡聚糖是一种具有多种生物功能的细胞壁结构多糖，但天然的酵母β-葡聚糖水溶性较差，影响了其在医疗、保健食品和化妆品行业中的应用。作者通过β-1，3-葡聚糖水解酶Gly5m和β-1，6-葡聚糖水解酶BT3312水解酵母β-葡聚糖制备小分子酵母葡聚糖，提高其水溶性。以大肠杆菌为宿主，异源表达β--1，3-葡聚糖水解酶Gly5m和β-1，6-葡聚糖水解酶BT3312。在25 ℃条件下，添加0.2 mmol/L IPTG诱导后，Gly5m和BT3312的最高酶活分别为1 0β86 U/mL和2 355 U/mL。酵母β-葡聚糖经过Gly5m和BT3312水解后，溶解率分别提高了2.6倍和2.4倍。采用Gly5m和BT3312共同水解，酵母β-葡聚糖溶解率提高了3.2倍（水溶性酵母葡聚糖的质量浓度为12.5 g/L）。因此，Gly5m和BT3312在提高酵母葡聚糖的水溶性和制备小分子酵母葡聚糖领域具有重要的应用价值。

Abstract:

Yeast β-glucan is a component of cell wall structural polysaccharide with various biological functions. However, the poor water solubility of natural yeast β-glucan has limited its application in medical, health food and cosmetic industries. The low molecule β-glucan was prepared to improve the solubility by degradation of yeast β-glucan using β-1,3-glucanase Gly5m and β-1,6-glucanase BT3312. Heterologous expression of β-1,3-glucanase Gly5m and β-1,6-glucanase BT3312 were expressed by Escherichia coli. After induced with 0.2 mmol/L IPTG at 25 ℃, the highest enzyme activities of Gly5m and BT3312 were 1 086 U/mL and 2 355 U/mL, respectively. The solubility of yeast β-glucan separately hydrolyzed by Gly5m or BT3312 increased by 2.6 or 2.4 times. The solubility of yeast β-glucan co-hydrolyzed by Gly5m and BT3312 increased by 3.2 times, and the concentration of water-soluble yeast glucan reached 12.5 g/L. Therefore, Gly5m and BT3312 have important application value in improving the water solubility of yeast glucan and preparing small molecule yeast glucan.