Hyperactive α-amylase production by Aspergillus oryzae IFO 30103 in a new bioreactor.

AIMS

To improve the α-amylase production in solid-state fermentation (SSF) condition utilizing a new bioreactor (NB) system.

METHODS AND RESULTS

In NB system, 20 g of wheat bran moistened with liquid medium in 1:1 ratio (w/v) was taken on the tray present inside the upper vessel and an additional 80 ml medium was supplemented into the lower vessel. Oxygen uptake rate was improved by supplying compressed air that lifted the liquid medium into the upper vessel and touched the substrate bed. This condition probably facilitated the heat transfer to liquid medium, reduce water loss and catabolite repression. With 1% glucose supplementation, maximum α-amylase activity of 22 317 Ugds(-1) was produced by Aspergillus oryzae IFO 30103 within a very short incubation period (48 h) at 2-cm bed height with air flow rate of 0·1 l min(-1)  g(-1) wheat bran at 32°C and initial medium pH of 6.

CONCLUSIONS

Within a short incubation period, significantly high α-amylase activity was obtained and it is higher than those reported to date at bioreactor scale operating with a fungal strain.

SIGNIFICANCE AND IMPACT OF THE STUDY

The reactor is novel and can overcome some of the major problems associated with SSF process. A. oryzae IFO 30103 is reported as the best fungal source for α-amylase production.