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alpha-Amylase production in high cell density submerged cultivation of Aspergillus oryzae and A. nidulans
- Agger, T., Spohr, A.B., Nielsen, J.
- Applied microbiology and biotechnology 2001 v.55 no.1 pp. 81-84
- Aspergillus oryzae, alpha-amylase, biomass, carbon, fermentation, genes, mixing
- The effect of biomass concentration on the formation of Aspergillus oryzae alpha-amylase during submerged cultivation with A. oryzae and recombinant A. nidulans strains has been investigated. It was found that the specific rate of alpha-amylase formation in chemostats decreased significantly with increasing biomass concentration in the range of approx. 2-12 g dry weight kg(-1). When using a recombinant A. nidulans strain in which the gene responsible for carbon catabolite repression of the A. oryzae alpha-amylase gene (cre A) was deleted, no significant decrease in the specific rate of alpha-amylase formation was observed. On the basis of the experimental results, it is suggested that the low value of the specific alpha-amylase productivity observed at high biomass concentration is caused by slow mixing of the concentrated feed solution in the viscous fermentation medium.