Identification and Functional Characterization of a Fructooligosaccharides-Forming Enzyme from Aspergillus aculeatus

Area of Science:

• Enzymology
• Biotechnology
• Food Science

Background:

• Fructosyltransferases (FTs) from Aspergillus aculeatus are of interest for prebiotic production.
• However, their amino acid sequences and structural characteristics have not been previously elucidated.

Purpose of the Study:

• To sequence and characterize a heat-resistant fructosyltransferase (AcFT) from Aspergillus aculeatus.
• To investigate its structural features and potential for fructooligosaccharides (FOS) production.

Main Methods:

• Isolation and purification of AcFT from Pectinex Ultra SP-L via heat treatment.
• Analysis of enzyme isoforms (AcFT1 and AcFT2) including glycosylation, activity, pI, and optimal pH.
• Partial protein sequencing and homology modeling to determine structural features.
• Characterization of FOS production profile and transferase/hydrolase ratio.

Main Results:

• Two isoforms, AcFT1 and AcFT2, with optimal activity at 60°C were identified.
• Both isoforms exhibited high transfructosylation capability (~90%) producing kestose, nystose, and fructosylnystose.
• Partial sequencing identified AcFT as Aspac1_37092, a 654-residue FT. Homology modeling revealed a typical glycoside hydrolase family 32 (GH32) fold.

Conclusions:

• This study provides the first report on the amino acid sequence and structural features of a heat-resistant FOS-producing enzyme from Aspergillus aculeatus.
• The characterized AcFT enzyme demonstrates significant potential for industrial applications in the prebiotics sector.