Evolutionary dynamics of microbial communities in bioelectrochemical systems

Abstract

SUMMARYBio-electrochemical systems can generate electricity by virtue of mature microbial consortia that gradually and spontaneously optimize performance. To evaluate selective enrichment of these electrogenic microbial communities, five, 3-electrode reactors were inoculated with microbes derived from rice wash wastewater and incubated under a range of applied potentials. Reactors were sampled over a 12-week period and DNA extracted from anodal, cathodal, and planktonic bacterial communities was interrogated using a custom-made bioinformatics pipeline that combined 16S and metagenomic samples to monitor temporal changes in community composition. Some genera that constituted a minor proportion of the initial inoculum dominated within weeks following inoculation and correlated with applied potential. For instance, the abundance of Geobacter increased from 423-fold to 766-fold between −350 mV and −50 mV, respectively. Full metagenomic profiles of bacterial communities were obtained from reactors operating for 12 weeks. Functional analyses of metagenomes revealed metabolic changes between different species of the dominant genus, Geobacter, suggesting that optimal nutrient utilization at the lowest electrode potential is achieved via genome rearrangements and a strong inter-strain selection, as well as adjustment of the characteristic syntrophic relationships. These results reveal a certain degree of metabolic plasticity of electrochemically active bacteria and their communities in adaptation to adverse anodic and cathodic environments.

High-throughput 96-well bioelectrochemical platform for screening of electroactive microbial consortia

“…The electrochemical results from inocula screening indicated that the most electroactive consortia were obtained from the lakes that indicated the highest Cu content, ORP, and conductivity (yellow and purple, Table 1), which is consistent with previous studies pertaining to the effect of set potential on electrogenic biofilm growth [33,[47][48][49][50][51]. Colorful lakelets contained various Cu and Zn oxyminerals, and hence expected to be a relevant source of electroactive bacteria [42,[52][53][54].…”

Using ASAR for Analysis of Electrogenic and Human Gut Microbial Communities

“…Functional analyses of metagenomes from our lab scale experiments was sufficient to reveal metabolic changes between different species of the MFC dominant genus, Geobacter, suggesting that optimal nutrient utilization at the lowest electrode potential is achieved via genome rearrangements and a strong inter-strain selection, as well as adjustment of the characteristic syntrophic relationships. These observations show a certain degree of metabolic and genomic plasticity of electrochemically active bacteria and their communities in adaptation to adverse anodic and cathodic compartments (Szydlowski et al, 2019).…”

“…NADH-quinone oxidoreductase (nuoB/C/G/L, nuoD. nuoH genes) and NADH-ubiquinone oxidoreductase (nad3) genes show the strongest dependence on the applied potential and their abundancy evolves strongly over the period of the experiment (Szydlowski et al, 2019).…”

Novel species identification and deep functional annotation of electrogenic biofilms, selectively enriched in a microbial fuel cell array

“…The high abundance of EET-related and hydrocarbon degrading genes in pH 7 OCP, as seen in Table 1, as well as the total number of unique annotations may reflect higher metabolic diversity of this community due to the lack of external electron circuit. Indeed previous studies comparing MFC communities (Ishii et al, 2018;Kouzuma et al, 2018;Szydlowski et al, 2020) reveal higher functional diversity in communities grown at OCP, whereas the presence of external circuit applies selective pressure on the microbial metabolism.…”