Characterization of a mycelial fructosyltransferase from Aspergillus tamarii NKRC 1229 for efficient synthesis of fructooligosaccharides

An efficient system for biotransformation of sucrose to fructooligosaccharides (FOS) was obtained using Aspergillus tamarii NKRC 1229 mycelial fructosyltransferase (m-FTase). Zymographic analysis confirmed mycelial localization of the FTase (36 U/g) and lyophilized fungal pellets were used for bioconversion. m-FTase had molecular weight similar to 75 kDa with optimum activity at pH 7.0 and 20 degrees C. FOS production after parametric optimization (sucrose-50% w/v, m-FTase dose - 4.5% w/v, inoculum age - 48 h and incubation time-24 h) reached 325 g/L (55% yield) with 14% residual sucrose, 25% glucose and 6% fructose. FTase activity was enhanced after pre-treatment with organic solvents and SDS. FOS was purified in a single step using gel filtration matrix, Bio-Gel P2. FOS was characterized using Diffusion ordered spectroscopy-Nuclear Magnetic Resonance (H-1 DOSY-NMR) and Fourier-transform infrared spectroscopy (FTIR). Continuous generation of FOS was achieved using recyclable mycelia upto 10 consecutive cycles.