Synthetic Saccharomyces cerevisiae‐Shewanella oneidensis consortium enables glucose‐fed high‐performance microbial fuel cell

Abstract

Microbial fuel cells (MFCs) were green and sustainable bio‐electrochemical reactors for simultaneous wastewater treatment and electricity harvest from organic wastes. However, exoelectrogens, such as Shewanella and Geobacter being widely studied in MFCs, could only use a limited spectrum of carbon sources. To expand the carbon source range being used in MFCs, we herein rationally designed a glucose‐fed fungus‐bacteria microbial consortium including a fermenter (Saccharomyces cerevisiae) in which the ethanol pathway was knocked out and the lactic acid biosynthesis pathway from Bovin was introduced into S. cerevisiae, and an exoelectrogen (Shewanella oneidensis MR‐1). We optimized the co‐culturing conditions of the microbial consortium to achieve an optimal coordination between carbon source metabolism of the fermenter and extracellular electron transfer of the exoelectrogen, such that lactate, the metabolic product of glucose by the recombinant S. cerevisiae, was continuously supplied to S. oneidensis in a constant level until glucose exhaustion. This metabolic coordination between the fermenter and the exoelectrogen enabled bioelectricity production in a glucose‐fed MFC. Furthermore, a porin protein encoded by oprF gene from Pseudomonas aeruginosa was incorporated into the outer membrane of S. oneidensis to enhance membrane permeability and its hydrophobicity, which in turn facilitated its biofilm formation and power generation. The glucose‐fed MFC inoculated with the recombinant S. cerevisiae‐recombinant S. oneidensis generated a maximum power density of 123.4 mW/m2, significantly higher than that of recombinant S. cerevisiae‐wild‐type S. oneidensis (71.5 mW/m2). Our design strategy of synthetic microbial consortia was highly scalable to empower the possibility of a wide range of carbon sources being used in MFCs, e.g., xylose, cellulosic biomass, and recalcitrant wastes. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1830–1838, 2017

Shewanella oneidensis MR-1 electron acceptor taxis and the perception of electrodes poised at oxidative potentials

“…In contrast to Geobacter sp, which forms thick (20-45 m) and stable electroactive biofilms [16][17][18], MR-1 forms thinner (1-16 m) and relatively loosely adherent biofilms and typically populates electrodes only partially [18][19][20][21]. Geobacter sp also generally perform better regarding maximum current density of MFCs.…”

Interkingdom microbial consortia mechanisms to guide biotechnological applications

“…This study further demonstrates that interkingdom consortia can be utilized even for the synthesis of complex pharmaceutical and therapeutic compounds, such as alkaloids and flavonoids. Moreover, depending on the interkingdom consortia designed, various carbon sources could be used to produce the desired effects, enabling flexibility (Table 2) (Lin et al, 2017). Further tests for each consortium should also be carried out to ensure the optimum ratio of each species (starting inoculum), starting compound and highyield production.…”

Fungi-Based Microbial Fuel Cells

“…It is commonly known that the fermentative microorganisms of the consortium can transform large organic molecules into smaller fermentation products that can be used by electrogenic species. Lin et al designed an MFC that employed a microbial consortium, including the electrogen Shewanella oneidensis MR-1 and genetically engineered S. cerevisiae as a fermenter, with glucose as a carbon source [56]. The ethanol pathway was knocked out in S. cerevisiae cells, while the lactic acid pathway was programmed in the cells.…”