Enzymatic synthesis of novel oligosaccharides from N-acetylsucrosamine using β-fructofuranosidase from Aspergillus oryzae

•Novel oligosaccharides were produced from N-acetylsucrosamine.•N-Acetyl-1-kestosamine and N-acetylnystosamine were produced.•Aspergillus oryzae β-fructofuranosidase was used for the oligosaccharide production.•These oligosaccharides were produced also by using dried A. oryzae mycelia.•We prepared A. oryzae mycelia suitable for the production of these oligosaccharides.

Mycelia of Aspergillus oryzae NBRC100959 contain 2 types of β-fructofuranosidases, transfructosylation-catalyzing enzyme (βFFaseI), and hydrolysis-catalyzing enzyme (βFFaseII). Using βFFaseI extracted from the mycelia of strain NBRC100959, two novel oligosaccharides consisting of GlcNAc and fructose, β-d-fructofuranosyl-(2→1)-β-d-fructofuranosyl-(2↔1)-2-acetamido-2-deoxy-α-d-glucopyranoside (N-acetyl-1-kestosamine, 1-KesNAc) and β-d-fructofuranosyl-(2→1)-β-d-fructofuranosyl-(2→1)-β-d-fructofuranosyl-(2↔1)-2-acetamido-2-deoxy-α-d-glucopyranoside (N-acetylnystosamine, NysNAc), were synthesized from β-d-fructofuranosyl-(2↔1)-2-acetamido-2-deoxy-α-d-glucopyranoside (N-acetylsucrosamine, SucNAc). We next planned to synthesize 1-KesNAc and NysNAc using A. oryzae mycelia. However, it was thought that the presence of βFFaseII is disadvantageous for the production of these oligosaccharides by βFFaseI, because βFFaseII hydrolyzed 1-KesNAc and NysNAc. We succeeded to produce A. oryzae mycelia containing βFFaseI as the major β-fructofuranosidase, by increasing sucrose concentration in the culture medium. Then, using a dried sample of these A. oryzae mycelia, reaction for the oligosaccharide production was performed. As the results, 190 mg of 1-KesNAc and 60 mg of NysNAc were obtained from 0.6 g of SucNAc. This whole-cell catalysis method facilitates the synthesis of 1-KesNAc and NysNAc because extraction and purification of βFFaseI from mycelia are unnecessary.

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