Bioelectrochemical assessment of a novel electrogenic Bacillus altitudinis AC11.2 for electricity generation in microbial fuel cell (MFC) system.

Electrogen is a microbial group that plays an important role as anodic biocatalyst of microbial fuel cells (MFCs), one of the most extensively studied microbial-based technologies for bioelectricity generation. The aims of this research were to isolate potential electrogenic bacteria from aquaculture pond sediments and conduct a thorough evaluation on the MFCs' electricity production and efficiency parameters. A total of 18 electrogenic bacteria having various electrochemical abilities was successfully isolated using thioglycollate solid media enriched with Fe³⁺. Five isolates (namely KCf1, KCf2, KCf4, KCf10, and KCf14) were non-pathogenic electrogens and able to produce relatively stable and high open-circuit voltage values (690–810 mV) on glucose-fed MFCs. Further evaluations on electricity production in close-circuit mode (fixed resistor technique, polarization tests, and analysis of power overshoot phenomenon) and efficiency parameters (Coulombic and energy efficiencies) showed that KCf2, molecular identified as Bacillus altitudinis AC11.2, was the most potential MFC biocatalyst among all isolates. It produced an MPP value of 67.11 mW m⁻², current density of 333.03 mA m⁻², and Coulombic and energy efficiency of 53.86% and 63.27%, respectively. Efforts to increase the MFC's electrical output have been done by assembling four reactors in series and parallel circuits, obtaining the maximum total voltage of 1.6–2.0 V (for series configuration). This potential output was higher than a portable zinc–carbon battery (1.5 V) and a Ni–Cd battery (1.2 V). However, the voltage reversal suffered in series circuits was another challenge in the development of MFCs for bioelectricity production, since the existence of this phenomenon due to biological factors (microbial metabolism dynamics) are not easy to be controlled. [ABSTRACT FROM AUTHOR]