Precultures were grown in 150 mL serum bottles with rubber septum under anaerobic conditions. The serum bottles were filled with preboiled growth medium and flushed with free O2 nitrogen. Before inoculating the preculture with the first post-sporal Hungate-tube culture, a heat shock was performed at 80 °C for 3.5 min to stimulate the germination of spores. The preculture was then inoculated (10% v/v) and incubated at 35 °C without agitation for 24 h. After the microorganism growth, the reactor was inoculated at 10% (v/v) and the pH was set at 6.2 by the addition of NaOH 3 M.