Modelling MgCO3 buffered succinic acid production by Actinobacillus succinogenes

Abstract

Thie current study focused on using a previously published model known to accurately predict the cultivation of Actinobacillus succionogenes on glucose in a NaOH neutralised system, for the prediction of batch system behaviour when MgCO3 is used as a pH buffer in a batch reactor system. The use of MgCO3 as a neutralising agent resulted in a biomass growth lag of about 8 h, followed by a sharp increase untill 15 h at which point the biomass concentration remained constant throughout the fermentation run. The maximum biomass concentration was 3.62 g/L. The fermentation ceased at a final SA concentration of 38.12 g/L and the SA yield on glucose was 0.81 g/g from an initial glucose concentration of 60 g/L. At the end of the fermentation, 79 % of the glucose as consumed. A residual glucose concentration of 12.84 g/L at the maximum SA concentration indicated product-related inhibition. The biomass, acetic acid (AA), and formic acid (FA) concentrations were incorrectly predicted by the model which implies that the use of MgCO3 as a buffer agent changed the metabolic fluxes of the organism.