Fig. 2

Role of calcium and carbonate ions on butanol production by strain BOH3 in defined medium amended with cassava. Blank stands for absence of CaCO₃, CaCl₂ stands for 10 mM CaCl₂, Na₂CO₃ stands for 10 mM Na₂CO₃, CaCl₂ + Na₂CO₃ stands for 10 mM CaCl₂ and 10 mM Na₂CO₃, CaCO₃ stands for 10 mM CaCO₃. The fermentation was performed at 37 °C for 96 h. Initial cassava flour concentration is 100 g/L containing 68 g/L of starch. Data represent the mean ± SD of triplicate individual experiments