Relationship between biodiversity and power generated by anodic bacteria enriched from petroleum-contaminated soil at various potentials

Abstract

Microbial Fuel Cell (MFC) technology has become an alternative platform for bioremediation and power generation. Herein, three different potentials (−0.3 V, 0.0 V, +0.3 V vs Ag/AgCl) were used to improve the ability of the microbial community to degrade diesel fuel and assess their long-term community behaviour. The maximum current density was observed for the anode poised at −0.3 V (0.92 mAcm⁻²). Biofilm characterisation revealed that the most diverse bacterial community was obtained from the surface of the anode operated at −0.3 V. It was the most abundant in Rhodococcus and Mycobacterium species, which are capable of biosurfactant production and hydrocarbon degradation. In addition, negative potential promoted the growth of electroactive genera such as Geobacter and Desulfovibrio. That led to a superior power density of 83.2 mWm⁻², compared to 20.9 and 31.6 mWm⁻² at 0.0 and +0.3 V, respectively. The SEM analysis illustrated the morphologies of anodic biofilms, indicating the presence of conductive nanowires at −0.3 V. Electrochemical and bacterial community data demonstrated a correlation between community diversity and power output at different potentials. Furthermore, we have detected several microbial taxa capable of biosurfactant production. These results revealed the most effective approaches to enriching communities in petroleum-contaminated soil. This is the first time that various poised potentials were studied to enrich electroactive communities targeting diesel fuel degradation, with a focus on understanding dynamic changes of these communities.