Carbon‐ and nitrogen‐limited growth of Penicillium chrysogenum in fed batch culture: The optimal ammonium ion concentration for penicillin production

Abstract

AbstractFed batch culture was used to investigate penicillin production when the growth of Penicillium chrysogenum was limited by the supply of either sucrose and or ammonium ions. It was found that a ‘quasi steady state’ (in which the growth rate was virtually equal to the dilution rate) could be established under these conditions. Some metabolic parameters (specific sucrose consumption rate and growth yields) were dependent on the ratio of sucrose: ammonium ions in the feed medium over a range of ammonium concentrations both above and below the double substrate‐limited point. The maximum specific rate of penicillin production required the supply of a large excess of ammonium ion, about five times the growth‐limiting level. That is, the ratio of ammonium‐nitrogen: sucrose, fed to the (sucrose‐limited) culture, was 0.11 and the residual ammonium ion concentration was in excess of 18 mmol dm−3, at a dry biomass concentration of 0.6%.