Overproduction of a β-fructofuranosidase1 with a high FOS synthesis activity for efficient biosynthesis of fructooligosaccharides.

Aureobasidium melanogenum 11-1 was found to be able to produce over 281.7 ± 7.1 U/mL of β-fructofuranosidase activity. The protein deduced from the cloned β-fructofuranosidase1 gene had the conserved motif A (IGDP), motif D (RDP) and motif E (ET) and 11 N-glycosylation sites, indicating it was a β-fructofuranosidase with the high-level fructooligosaccharide (FOS) biosynthesis. Overexpression of the β-fructofuranosidase1 gene in the yeast strain 11-1 made a tranformant 33 produce 557.7 U/mL of β-fructofuranosidase activity. The molecular weight of the β-fructofuranosidase1 in which all the carbohydrates were removed by the Endo-H was 82.4 kDa. Within 7 h of the transfructosylation reaction, the yield of FOS was 0.66 g of FOS/g of sucrose and percentages of GF2, GF3 and GF4 were 79.5%, 18.9% and 1.6%. This demonstrated that the β-fructofuranosidase1 and the transformant 33 had highly potential applications in biotechnology for FOS production.