Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9602425 | Biomolecular Engineering | 2005 | 10 Pages |
Abstract
Oxygen transfer in the fungal mat is a major concern in solid-state fermentation (SSF). Oxygen supply into the mycelial layers is hampered by diffusion limitation. For aerobic fungi, like Aspergillus oryzae, this oxygen depletion can be a severely limiting factor for growth and metabolite production. This paper describes the effects of a low oxygen concentration on growth at the levels of individual hyphae, colonies and overcultures, and on α-amylase production in overcultures. PDA medium was used to study the effect of a low oxygen concentration on hyphal elongation rate and branching frequency of hyphae, and radial extension rate of colonies of A. oryzae. We found similar saturation constants (KO2) of 0.1% (v/v in the gas phase) for oxygen concentration described with Monod kinetics, for branching frequency of hyphae and colony extension rate. When A. oryzae was grown as an over-culture on wheat-flour model substrate at 0.25% (v/v) oxygen concentration, the reduction in growth was more pronounced than as individual hyphae and a colony on PDA medium. Experimental results also showed that the specific α-amylase production rate under the condition of 0.25% (v/v) oxygen was reduced. Because the value of KO2 is relatively low, it is reasonable to simplify the kinetics of growth of A. oryzae to zero-order kinetics in coupled diffusion/reaction models.
Related Topics
Physical Sciences and Engineering
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Bioengineering
Authors
Yovita S.P. Rahardjo, Susana Sie, Frans J. Weber, Johannes Tramper, Arjen Rinzema,