The p FNB removal occurred

The p-FNB removal occurred in the following order: TBES > MBES > TECS > MECS > MBS > TBS ( Fig. 1). These findings indicated that microbial degradation of p-FNB in the BS was suppressed by high-temperature, but microbial specificity for p-FNB degradation was well preserved or elevated in the BES with the cooperative electrical stimulation. The poorest degradation efficiency of p-FNB in the TBS indicated that microbial nitro-group Atractyloside and dehalogenation were inhibited by high-temperature, which is similar to the results reported by Kohring et al. (1989). As the culture temperature increased from 30 °C to 55 °C, the energy needed for microbial growth maintenance is increased by almost ten-fold ( Heijnen and Kleerebezem, 2010), and the poor p-FNB degradation efficiency was owing to the inability of refractory p-FNB providing enough electron donors in the chemical form. Since the microbial communities used in the present study originated from identical sources, individual high temperature may exert an adverse effect on the evolution of unique communities for p-FNB degradation, while the cooperative role of electrical stimulation can supply additional electrons from solid-state electrodes for microbial respiration ( Gregory et al., 2004), benefiting communities capable of p-FNB degradation.