The inhibition effect of methanol, as a component of crude glycerol, on the growth rate of Cupriavidus necator and other micro-organisms

• Methanol at all concentrations tested has adverse effect on growth of Cupriavidus necator.
• A model for predicting reduction in C. necator growth is proposed.
• The model was found to fit the experimental data very well.
• Plausible inhibition mechanisms based on the model are proposed.
• The model is applicable to fermentation systems containing short chain alcohols.

Methanol is known for its toxicity to a wide range of micro-organisms. The presence of methanol in a system can significantly suppress microbial growth. In this paper, the growth of Cupriavidus necator DSM4058 in mineral medium containing methanol in a range 0–125 g/L is reported. It was found that methanol tested at any concentration had a negative influence on growth. However, the reduction in specific growth rate could be predicted by neither substrate nor product inhibition equations, and so a model, based on a saturation equation was developed and is presented here. The model is shown to fit particularly well, not only with the C. necator data but also with several sets of data extracted from publications based on other micro-organisms. It was found that the model successfully predicted the data with regression coefficients of over 96%, regardless of micro-organism or particular alcohol inhibitor.