Increasing the availability of oxygen promotes the metabolic activities and population growth of cable bacteria in freshwater sediments

Microbial succession in a marine sediment: Inferring interspecific microbial interactions with marine cable bacteria

“…Desulfosarcina , Desulfatiglans , and SEEP‐SRB1 are canonical sulfate‐reducing bacteria capable of utilizing diverse carbon substrates, with some isolates capable of degrading methane and other hydrocarbons (Jochum et al, 2018 ; Petro et al, 2019 ; Watanabe et al, 2017 ). Experiments have demonstrated that sulfide oxidation carried out by cable bacteria, combined with enhanced anion diffusion generated by their electric field, enriches sulfate at suboxic depths (Huo et al, 2022 ; Rao et al, 2016 ; Risgaard‐Petersen et al, 2012 ), which in turn can stimulate sulfate reduction, at least in sediments where sulfate reduction is limited by sulfate supply at depths occupied by cable bacteria (Marzocchi et al, 2020 ; Sandfeld et al, 2020 ). The association between sulfate reducers and cable bacteria activity has implications for biogeochemistry and bioremediation, for example by suppressing methanogenesis (Scholz et al, 2020 ), and stimulating the anaerobic degradation of organic compounds, including hydrocarbons (Liu et al, 2022 ), at least in low salinity systems.…”

“…By contrast, evidence from recent studies has pointed to the growth of cable bacteria as a stimulating factor for other microbes, promoting the activity of other bacterial taxa and/or biogeochemical processes (Kessler et al, 2019 ; Vasquez‐Cardenas et al, 2015 ), and driving an increase in microbial network complexity (Liu et al, 2022 ). These findings point to a different ecological role for cable bacteria—as providers of resources for other microbes, for example by solubilizing ferrous iron (Kessler et al, 2019 ), or by acting as an electron acceptor for chemoautotrophy, as hypothesized by Vasquez‐Cardenas et al ( 2015 ) and Otte et al ( 2018 ), and in freshwater or low salinity systems, by recycling sulfate at suboxic depths (Huo et al, 2022 ; Liu et al, 2022 ; Sandfeld et al, 2020 ). Cable bacteria may perform different ecological functions in different sediment horizons.…”

“…Since their discovery about a decade ago (Pfeffer et al, 2012 ), cable bacteria have been observed in a wide range of depositional sedimentary environments (Aller et al, 2019 ; Burdorf et al, 2016 ; Hermans et al, 2020 ; Scholz et al, 2021 ), and frequently at high cell densities (Malkin et al, 2017 ). Especially where these bacteria achieve high biomass, their metabolic activity can drive intense localized changes in pH and strongly influence the cycling of oxygen, sulfur, iron, manganese, phosphorus, carbonate, organic carbon, and trace metals (Huo et al, 2022 ; Rao et al, 2016 ; Risgaard‐Petersen et al, 2012 ; Sulu‐Gambari et al, 2016a , 2016b ; van de Velde et al, 2016 ), with impacts on the ecosystem level (Seitaj et al, 2015 ). The biogeochemical consequences of cable bacteria growth in sediments are not limited to their direct metabolic activities, but additionally involve their interspecific interactions with a myriad of other microorganisms in their complex sedimentary environment (Daghio et al, 2016 ; Liu et al, 2022 ; Scholz et al, 2021 ).…”