Fructooligosaccharides production by Aspergillus sp. N74 in a mechanically agitated airlift reactor

Batch fructooligosaccharides (FOSs) production by fructosyltransferase from Aspergillus sp. N74 in a mechanically agitated airlift reactor was investigated. Two biomass concentrations (6 and 9.5 g L^-1 in biomass dry weight) of Aspergillus sp. N74 were used for the evaluation of fructosyltransferase activity. The enzymatic reactions were carried out at the following conditions: initial sucrose concentration 70% (w/v), pH 5.5, 60 °C, 350 rpm, and superficial aeration rate 0.012 m s^-1; the reactor was operated in batch for 26 h. A biomass concentration and time reaction effect on FOS production and composition was observed. The obtained FOS yield (Y_FOS) for 6 g L^-1 of biomass dry weight was 69% (43% 1-kestose and 26% nystose), while for 9.5 g L^-1 of biomass dry weight a peak in the Y_FOS of 70% was observed (43% 1-kestose, 25% nystose and 2% 1-β-fructorianosyl nystose) after 4 h of reaction, which was reduced to the 57% (18% 1-kestose, 33% nystose and 6% 1-β-fructofuranosyl nystose) at the end of the reaction time. These results present the designed reactor and the native strain Aspergillus sp. N74 as an industrial alternative for the fructooligosaccharides production.