Utilisation of starch processing wastewater for production of microbial biomass protein and fungal α-amylase by Aspergillus oryzae

The production of microbial biomass protein (MBP) and fungal alpha-amylase from starch processing waste-water (SPW) by a selected strain Aspergillus oryzae was investigated as part of a comprehensive SPW treatment programme. A simple, non-aseptic, one-stage process was successfully carried out by using ail air lift bioreactor under the optimised growth conditions at pH 5.0 and 35 degrees C. Bioproduct yields of 6.1 g/litre of MBP that contained 38% protein, and 55 EU/ml of alpha-amylase enzyme were obtained from a 12-h batch culture. The pellet bioproduct led to easy harvesting of the biomass protein. The SPW was treated by removing 95% COD, 93% BOD and 98% suspended solids, and can be used for farm irrigation. The alpha-amylase had a stable enzyme activity at pH 5-9 and 25-35 degrees C. Pretreatment by hydrolysis and sterilization of SPW and nutrient supplementation may be unnecessary. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.