. That fermentation demonstrated better solvent production compared to the two-step process [30]. In addition, a study by Maddox et al. [31], an ABE fermentation conducted at low temperature (as low as 28 °C) made the culture became solventogenic instead of acidogenic. Higher solvents were obtained at the temperature of 34 °C compared to other temperature values, however, the pH must be maintained at 5.0 throughout the process. Thus, by referring to these previous reported experiments, the simultaneous process for ABE fermentation is possible to be conducted and its yield was comparable with the two-step process.