Glucoamylases production of Aspergillus niger in solid state fermentation using a continuous counter-current reactor

Abstract

This work presents the continuous production of fungal biomass and glucoamylase by solid state fermentation (SSF) in a counter-current reactor adapted for this purpose. Pre-germinated conidia of Aspergillus niger were used as an inoculum, and sugarcane bagasse, embedded with a nutritive solution, was the solid support. The solids residence time distribution (RTD) was carried out by feeding one impule of blue-coloured humidified bagasse and its RTD was fixed at 20 h. This study demonstrated that the values of the measured parameters (pH, moisture, biomass, glucoamylases production) were similar to those reported for batch SSF using the same solid support and micro-organism. A marked increase in biomass occurred from the progressive compartment (from compartment 1 to 9) into the reactor and the enzyme production was important (40 IU g(-1) dry exit solids). No mycelium damage or sporulation was observed by microscopy analysis. The above results confirmed that the continuous production of enzymes by SSF under no sterile conditions was successful. Inoculation with pre-germinated conidia shortened the processing time and allowed control of the age of the mycelium in each compartment. Aeration was accomplished by natural convection and moisture content had to be controlled. This process can be applied to the continuous production of fungal biomass and metabolites in SSF with industrial applications using environmental-friendly biotechnology.