Citric acid production byAspergillus foetidusin batch and fed‐batch cultures

Abstract

Abstract Sucrose and ammonium nitrate, respectively, were the preferred carbon and nitrogen sources for citric acid production by Aspergillis foetidus CCRC 30206. For a 7‐day fermentation, the maximal citric acid production of 7.2 ∼ 28.4 g/l appeared at an initial sucrose concentration of 12 % under various initial levels of nitrogen and phosphorous sources. Citric acid production commenced and ceased earlier in either the nitrogen‐limited (NH4NO3, 0.5g/l) or the phosphorous‐limited (KH2PO4, 0.2 g/1) medium. The richer media delayed the onset of citric acid production. Nonetheless, 48.3 g/1 of citric acid was produced in the medium rich in nitrogen (NH4NO3, 2.0 g/1) and phosphorous (KH2PO4, 1.4 g/1) when the batch culture was extended to 16 days. The cultivation time of this rich medium was reduced to 12 days in a fed‐batch culture under dual limitation of both nitrogen and phosphorous.