Anode surface bioaugmentation enhances deterministic biofilm assembly in microbial fuel cells

Abstract

Microbial fuel cells (MFCs) are devices that can generate energy while aiding biodegradation of waste through the activity of an electroactive mixed biofilm. Metabolic cooperation is considered essential for MFCs’ efficiency, especially during early-anode colonization. Yet, the specific ecological processes that drive the assembly of an optimized anode-attached community remain unknown. Here, we show, using 16S rRNA gene amplicon and shotgun metagenomic sequencing that bioaugmentation of the anode surface with an electroactive consortium originating from a well-established anodic biofilm, dominated by different Desulfuromonas strains, resulted in an extremely rapid voltage generation (reaching maximal voltage within several hours). This was in sharp contrast to the highly stochastic and slower biofilm assembly that occurred when the anode-surface was not augmented. By comparing two inoculation media, wastewater and filtered wastewater, we were able to illustrate two different "source-communities" for newly arriving species that with time colonized the anode surface in a different manner and resulted in dramatically different community assembly processes. Remarkably, an efficient anode colonization process was obtained only if unfiltered wastewater was added, leading to a near-complete replacement of the bioaugmented community by Geobacter lovleyi. We propose that anode bioaugmentation reduced stochasticity by creating available niches that were quickly occupied by specific newly-arriving species that positively supported the fast establishment of a highly-functional anode biofilm.

Engineering microbial technologies for environmental sustainability: choices to make

“…The similarity between economics and microbial behaviour even goes further, as trading of essential resources between microorganisms can accelerate the total growth of the microbial community (Tasoff et al ., 2015). In an open system, in which immigration of new microorganism can influence microbial assembly and function in the receiving engineered or natural ecosystem (Mei and Liu, 2019; Dottorini et al ., 2021), the complete process is carried out with more accuracy and a higher efficiency by multiple species than on an individual basis, as for example illustrated in anode biofilm assembly in microbial fuel cells (Yanuka‐Golub et al ., 2021).…”

Specific Desulfuromonas Strains Can Determine Startup Times of Microbial Fuel Cells

“…Phylogenetic analysis of this colony revealed that additional bacterial species were present (Supplementary Figure S3), therefore, we referred to it as a highly enriched electroactive consortium. Then, the colonies were applied on clean anodes by spreading the colony onto the anode surface, and then these anodes were inoculated inside MFCs [30]. Figure 5 compares the lag time and time to reach steady-state current density for all experimental sets conducted in this study.…”