Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, 5 Iroon Polytechniou Str., Zografou Campus, Athens, 15780, Greece.
Laboratory of Food Chemistry and Technology, School of Chemical Engineering, National Technical University of Athens, 5 Iroon Polytechniou Str., Zorgafou Campus, Athens, 157 80, Greece.
N Biotechnol. 2021 Jul 25;63:45-53. doi: 10.1016/j.nbt.2021.03.002. Epub 2021 Mar 15.
β-Galactosidases are key enzymes in the food industry. Apart from the hydrolysis of the saccharide bond of lactose, they also catalyze transgalactosylation reactions, producing galactooligosaccharides (GOS) with prebiotic activity. Here we report the heterologous production in Pichia pastoris of a novel β-galactosidase from the fungus Thermothielavioides terrestris. The enzyme (TtbGal1) was purified and characterized, showing optimal activity at 60 °C and pH 4. TtbGal1 is thermostable, retaining almost full activity for 24 h at 50 °C. It was applied to the production of GOS from defined lactose solutions and acid whey, a liquid waste from the Greek yoghurt industry, reaching yields of 19.4 % and 14.8 %, respectively. HILIC-ESI-QTOF-MS analysis revealed the production of GOS with up to 4 saccharide monomers. The results demonstrate efficient GOS production catalyzed by TtbGal1, valorizing acid whey, a waste with a heavy polluting load from the dairy industry.
β-半乳糖苷酶是食品工业中的关键酶。除了水解乳糖的糖键外，它们还催化转半乳糖基反应，产生具有益生元活性的半乳糖低聚糖（GOS）。在这里，我们报告了来自真菌Thermothielavioides terrestris 的新型β-半乳糖苷酶在巴斯德毕赤酵母中的异源生产。该酶（TtbGal1）被纯化并进行了表征，在 60°C 和 pH4 下表现出最佳活性。TtbGal1 具有热稳定性，在 50°C 下保持近 24 小时的几乎全部活性。它被应用于从定义的乳糖溶液和酸乳清（希腊酸奶工业的液体废物）生产 GOS，分别达到 19.4%和 14.8%的产率。HILIC-ESI-QTOF-MS 分析表明可生产出具有多达 4 个糖单体的 GOS。结果表明，TtbGal1 催化的 GOS 生产效率高，可利用具有高污染负荷的乳制品工业废物酸乳清。
