Combining microbial cultures for efficient production of electricity from butyrate in a microbial electrochemical cell

Abstract

Butyrate is an important product of anaerobic fermentation; however, it is not directly used by characterized strains of the highly efficient anode respiring bacteria (ARB) Geobacter sulfurreducens in microbial electrochemical cells. By combining a butyrate-oxidizing community with a Geobacter rich culture, we generated a microbial community which outperformed many naturally derived communities found in the literature for current production from butyrate and rivaled the highest performing natural cultures in terms of current density (~11 A/m2) and Coulombic efficiency (~70%). Microbial community analyses support the shift in the microbial community from one lacking efficient ARB in the marine hydrothermal vent community to a community consisting of ~80% Geobacter in the anode biofilm. This demonstrates the successful production and adaptation of a novel microbial culture for generating electrical current from butyrate with high current density and high Coulombic efficiency, by combining two mixed micro bial cultures containing complementing biochemical pathways.

A Generalized Model for Complex Wastewater Treatment with Simultaneous Bioenergy Production Using the Microbial Electrochemical Cell

“…4b) decrease from interface to the anode surface. Moreover, as it has been proved by experiments [45,46] the major biofilm microorganisms are electrogens and for this simulation the mean value of electrogens to methanogens ratio is 5.94. The biofilm thickness varied dynamically from 11 micron to 14.6 micron over time (Fig.…”

A combined model for large scale batch culture MFC-digester with various wastewaters through different populations

“…The oxidation of acetate by the electrogenic bacteria and endogenous respiration processes are the main sources of electron generation. Thus, the electron mass balance is defined as follows [13]: (24) where , are determinations of electrons generated by substrate consumption (molekgCODS -1 ) and self-oxidation of biomass through endogenous respiration (mole-kgCODX -1 ), and show the fraction of energy-generating electrons (dimensionless) and time conversion factor (86400 s day -1 ), respectively.…”

“…These microbial groups are therefore in A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 5 competition with one another. Due to the assumption that electrons are transferred by the conduction-based mechanism, not mediated transfer, electrogens are considered existent in the biofilm [24,25]. The degradation rate of organic wastewater, and rate of acetate consumption by acetoclastic methanogenic bacteria in the liquid bulk are represented as follows [21]: …”

Synthetic Ecology of Microbes: Mathematical Models and Applications

“…Syntrophic microbial consortia are widely used in microbial fuel cells, where multiple fermentative bacteria degrade a mixture of complex organic pollutants and exoelectrogenic microorganisms (typically Geobacter species) rapidly convert fermentation intermediates into electrical current or chemicals/biofuels thereby eliminating their feedback inhibition on fermentative bacteria 106 . Synthetic microbial consortia have been used to design more efficient microbial fuel cells 107; 108; 109; 110; 111; 112; 113 . A notable example is the study by Venkataraman et al 110 , which demonstrated that a mutualistic co-culture of Pseudomonas aeruginosa and Enterobacter aerogenes in a bioelectrochemical system leads to up to 14-fold increase in electric power generation compared to either of the monocultures.…”

“…A more recent study addressed the issue that butyrate, which is an anaerobic fermentation by-product is not directly used by Geobacter sulfurreducens in anode. A synthetic consortium composed of two different but complementary mixed cultures was designed for the anode to overcome this issue, where one oxidizes butyrate to acetate and the other (enriched in Geobacter species) produces electric current by the consumption of acetate 112 . This synthetic community led to an enhanced production of electric current that outperformed the previous naturally derived communities.…”