Kinetic study and modelling of ethanol production from glucosexylose mixtures using the genetically-engineered strain Escherichia coli KO11

Abstract

Kinetics of ethanol fermentation on different synthetic glucose/xylose mixtures using Escherichia coli KO11 was studied. No substrate inhibition was observed in both glucose-only and xylose-only experiments. In single substrate fermentations, results show that glucose was the preferred substrate and its ethanol conversion rate was 1.5 times higher than the one obtained with xylose. In mixed-sugar fermentations, glucose was fully consumed significantly earlier than xylose, indicating an initial inhibition on xylose fermentation. The xylose consumption rate after the depletion of glucose significantly decreased with an increase in the initial glucose content. An unstructured kinetic model for ethanol production from glucose, xylose, and their mixtures using Escherichia coli KO11 was developed based on metabolic analysis. Ethanol inhibition and effect of pH were taken into account in the proposed model. Terms related to the inhibition on xylose metabolism by glucose were also included. Good agreement between model predictions and experimental data was obtained.