Biochemical characterization of a novel thermophilic α-galactosidase from Talaromyces leycettanus JCM12802 with significant transglycosylation activity

• A GH27 α-galactosidase was identified in T. leycettanus and expressed in P. pastoris.
• The recombinant Aga27A shows maximum activity at 70°C and is thermotolerant at 65°C.
• It's acidic with optimal activity at 4.0 and keeps stable over pH 3.0–11.0 at 70°C.
• It has strong resistance to most metal ions and great tolerance to galactose.
• It shows the preferable transglycosylation capacity with various substrates.

Thermophilic α-galactosidases have great potentials in biotechnological and medicinal applications due to their high-temperature activity and specific stability. In this study, a novel α-galactosidase gene of glycoside hydrolase family 27 (aga27A) was cloned from Talaromyces leycettanus JCM12802 and successfully expressed in Pichia pastoris GS115. Purified recombinant Aga27A (rAga27A) was thermophilic and thermotolerant, exhibiting the maximum activity at 70°C and retaining stability at 65°C. Like most fungal α-galactosidases, rAga27A had an acidic pH optimum (pH 4.0) but retained stability over a boarder pH range (pH 3.0–11.0) at 70°C. Moreover, the enzyme exhibited strong resistance to most metal ions and chemicals tested (except for Ag+ and SDS) and great tolerance to galactose (19 mM). The preferable transglycosylation capacity of rAga27A with various substrates further widens its application spectrum. Thus rAga27A with excellent enzymatic properties will be ideal for applications in various industries, especially for the synthesis of galactooligosaccharides.