Production of fructooligosaccharides by the mycelia of Aspergillus japonicus immobilized in calcium alginate

This work describes fructose oligosaccharide (FOS) production by the immobilized mycelia (IM) of a strain of Aspergillus japonicus, isolated from soil. The microorganism was inoculated into 50 ml of medium composed of sugar cane molasses (5•0% of total sugars); yeast powder, 2•0%; K2HPO4, 0•5%; NaNO3, 0•2%; MgSO4•7H2O, 0•05%; KCl, 0•05%, final pH 5•0, and the flasks were agitated in an orbital shaker at 200 rpm for 60 h, at 30°C. The β-fructofuranosidase activity (Uf), transfructosylating activity (Ut), hydrolyzing activity (Uh), and FOS production were analyzed by high performance liquid chromatography. FOS production was performed in a batch process in a 2-l jar fermenter by IM in calcium alginate beads. The optimum pH and temperature were 5•0–5•6 and 55°C, respectively. No loss of activity was observed when the mycelium was maintained at 60°C for 60 min. Maximum production was obtained using 5•75% (cellular weight/volume) of mycelia (122•4 Ut g−1) and 65% sucrose solution (w:v) for 4 h of reaction, when the final product reached 61•28% of total FOS containing GF2 (30•56%), GF3 (26•45%), GF4 (4•27%), sucrose (9•6%) and glucose (29•10%). In the assay conditions, 23 batches were performed without loss of activity of the IM, showing that the micro-organism and the process utilized have potential for industrial applications.