Cable bacteria with electric connection to oxygen attract flocks of diverse bacteria

Abstract

Cable bacteria are centimeter-long filamentous bacteria that conduct electrons via internal wires, thus coupling sulfide oxidation in deeper, anoxic sediment with oxygen reduction in surface sediment. This activity induces geochemical changes in the sediment, and other bacterial groups appear to benefit from the electrical connection to oxygen. Here, we report that diverse bacteria swim in a tight flock around the anoxic part of oxygen-respiring cable bacteria and disperse immediately when the connection to oxygen is disrupted (by cutting the cable bacteria with a laser). Raman microscopy shows that flocking bacteria are more oxidized when closer to the cable bacteria, but physical contact seems to be rare and brief, which suggests potential transfer of electrons via unidentified soluble intermediates. Metagenomic analysis indicates that most of the flocking bacteria appear to be aerobes, including organotrophs, sulfide oxidizers, and possibly iron oxidizers, which might transfer electrons to cable bacteria for respiration. The association and close interaction with such diverse partners might explain how oxygen via cable bacteria can affect microbial communities and processes far into anoxic environments.

Electron Transfer in the Biogeochemical Sulfur Cycle

“…In benthic microbial fuel cells, cable bacteria may interact with other electrogenic bacteria (e.g., in the family Desulfuromonadaceae) through extracellular electron transfer. Recently, Bjerg et al discovered through Raman microscopy that diverse bacteria form a tightly packed flock around the anoxic part of cable bacteria in a freshwater sediment enrichment culture [25]. Further analysis indicated that these flocking bacteria included sulfide oxidizers, which might transfer electrons to cable bacteria for sulfur oxidation.…”

“…Meanwhile, a recent study has discovered that cable bacteria mediating electrogenic sulfur oxidation can enhance the bioavailability of pyrene and promote the enrichment of degradative bacteria, thereby facilitating the removal of pyrene [82]. Therefore, the unique biological characteristics of cable bacteria endow them with a significant role in global biogeochemical cycles, and the LDET is advantageous for a variety of applications, such as microbial fuel cells for electricity generation or bioremediation of organic contaminants in sediments [25].…”

“…For instance, electron transfer occurs in consortia of sulfate-reducing bacteria and anaerobic methanotrophic archaea (ANMEs) [20][21][22], as well as in a novel multicellular filamentous bacterium known as cable bacteria [23]. These cable bacteria are not only capable of oxidizing sulfide through long-distance electron transfer (LDET) but can also receive electrons from other sulfur oxidizers [24,25]. These findings add to the complexity of the biogeochemical sulfur cycle while also explaining the key consequences of electron transfer in this cycle.…”

Enhancing Clinical Utility: Utilization of International Standards and Guidelines for Metagenomic Sequencing in Infectious Disease Diagnosis

“…Mapping longer sequences (70 bp to 1 Mbp), share similar features such as long-read support and split alignment [180] SAMtools (v1.19.2) Manipulating and analyzing sequence alignment data, crucial for post-processing and downstream analysis of metagenomic data [181,182] De Novo Metagenome Assembly MEGAHIT (v1.2.9)…”

Editorial: Electromicrobiology—from electrons to ecosystems, volume II

“…Cable bacteria are surrounded by a veil of microorganisms that swim around them (Thorup et al, 2021 ). These veil microorganisms dispersed once the cable bacterium was physically cut (Bjerg et al, 2023 ). In this volume, Lustermans et al investigate whether the presence of the microbial veil is connected to a cable bacteria progression and senescence in its environment and the subsequent geochemical changes.…”