A novel thermophile β-galactosidase from Thermothielavioides terrestris producing galactooligosaccharides from acid whey

?-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 ?-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.

Automated summary

Galactosidases play a crucial role in the food industry, especially in the production of galactooligosaccharides with prebiotic activity. A novel β-galactosidase from the fungus Thermothielavioides terrestris was successfully produced heterologously in Pichia pastoris, showing optimal activity at 60℃ and pH 4. The enzyme, TtbGal1, demonstrated efficient production of GOS from lactose solutions and acid whey, highlighting its potential to valorize waste from the dairy industry.