We expressed a putative β-galactosidase Asac_1390 from hyperthermophilic crenarchaeon Acidilobus saccharovorans in Escherichia coli and purified the recombinant enzyme. Asac_1390 is composed of 490 amino acid residues and showed high sequence similarity to family 1 glycoside hydrolases from various thermophilic Crenarchaeota. The maximum activity was observed at pH 6.0 and 93°C. The half-life of the enzyme at 90°C was about 7 hours. Asac_1390 displayed high tolerance to glucose and exhibits hydrolytic activity towards cellobiose and various aryl glucosides. The hydrolytic activity with p-nitrophenyl (pNP) substrates followed the order pNP-β-D-galactopyranoside (328 U mg⁻¹), pNP-β-D-glucopyranoside (246 U mg⁻¹), pNP-β-D-xylopyranoside (72 U mg⁻¹), and pNP-β-D-mannopyranoside (28 U mg⁻¹). Thus the enzyme was actually a multifunctional β-glycosidase. Therefore, the utilization of Asac_1390 may contribute to facilitating the efficient degradation of lignocellulosic biomass and help enhance bioconversion processes.

中文翻译：

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一种新型的高度热稳定的多功能β-糖苷酶，其来自Crnarchaeon Acidilobus saccharovorans。

我们在大肠杆菌中表达了一种超嗜热克雷氏嗜酸杆菌嗜糖菌的推定β-半乳糖苷酶Asac_1390，并纯化了重组酶。Asac_1390由490个氨基酸残基组成，与来自各种嗜热Crenarchaeota的Family 1糖苷水解酶具有很高的序列相似性。在pH 6.0和93°C时观察到最大活性。该酶在90°C的半衰期约为7小时。Asac_1390显示出对葡萄糖的高度耐受性，并表现出对纤维二糖和各种芳基葡糖苷的水解活性。对硝基苯基（pNP）底物的水解活性遵循pNP - β -D-吡喃半乳糖苷（328 U mg ^-1），pNP-β -D-吡喃葡糖苷（246毫克ü ^-1），PNP- β -D-吡喃木糖苷（72毫克ü ^-1），和PNP- β -D-吡喃甘露糖苷（28毫克ü ^-1）。因此，该酶实际上是多功能的β-糖苷酶。因此，Asac_1390的利用可能有助于促进木质纤维素生物质的有效降解，并有助于增强生物转化过程。