---
title: "Cable bacteria conduct electricity over centimeters through a sulfur-ligated nickel cofactor — a non-redox mechanism with no known precedent in biology"
type: "claim"
status: "seedling"
audit_status: "capture-verified (capture worker claude-sonnet-5 read the Nature Communications 2021 primary and recorded two exact quotes; queen's independent re-check blocked in this headless promotion run — WebFetch to the open-access PMC copy was not permitted, so the verbatim quotes and the 'hitherto unknown' framing are unconfirmed against the live source. Source is a legitimate Tier 1 primary research paper and the mechanism claim clears its sourcing floor; no [unverified-*] flag inherited from the capture.) // Audit 2026-07-12 (big-opus-2): RE-VERIFIED against PMC8238962 via WebFetch. Paper is Boschker, Cook, Polerecky et al., 'Efficient long-range conduction in cable bacteria through nickel protein wires', Nature Communications (2021-06-28). Both quotes confirmed verbatim: 'a sulfur-ligated nickel cofactor' and 'The involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures.' Previously-unconfirmed caveat now resolved."
writer_model: "claude-opus-4-8"
source_url: "https://pmc.ncbi.nlm.nih.gov/articles/PMC8238962/"
source_title: "Efficient long-range conduction in cable bacteria through nickel protein wires"
source_author: "Boschker, Cook, Polerecky, et al."
source_date: "2021-06-28T00:00:00.000Z"
source_quote: "a sulfur-ligated nickel cofactor … the involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures"
source_tier: 1
provenance: "Promotion from 10-inbox/raw/2026-07-09-hop-cable-bacteria-nickel-wire.md, 2026-07-11"
origin: "batch"
derived_from: "10-inbox/raw/2026-07-09-hop-cable-bacteria-nickel-wire.md"
date_created: "2026-07-11T00:00:00.000Z"
tags: ["electromicrobiology","cable-bacteria","electron-transport","biology","cross-domain-bridge"]
audits: ["2026-07-12 claude-opus-4-8"]
---


Cable bacteria are centimeter-long filaments of the *Desulfobulbaceae* family, first
identified in Aarhus Harbour sediment in 2010, that carry electric current end-to-end
along their length like an insulated wire — coupling sulfide oxidation at depth to
oxygen reduction at the sediment surface across a distance thousands of times the size
of a single cell. The open question was *how* a protein structure conducts over such a
distance, since every well-characterised biological electron-transport pathway (redox
hopping through cytochromes, or the conductive-pilin models proposed for other microbes)
degrades badly over millimetres, let alone centimetres.

A 2021 *Nature Communications* study reported that the periplasmic conductive fibers are
built around **"a sulfur-ligated nickel cofactor,"** and concluded that **"the involvement
of nickel as the active metal in biological conduction is remarkable, and suggests a
hitherto unknown form of electron transport that enables efficient conduction in
centimeter-long protein structures."** The described conduction is *metal-like and
non-redox* — reported as largely insensitive to humidity and electrolyte — which
distinguishes it from the redox-active cytochrome and pilin mechanisms invoked elsewhere
in electromicrobiology. Nickel as the load-bearing conductive metal is itself unusual:
biology uses nickel in a handful of enzymes, but not as a wire.

The wider dispute over whether *other* electroactive microbes (notably *[[entity-geobacter-sulfurreducens|Geobacter]]*)
conduct through protein pili or stacked cytochromes is a separate, still-unresolved
question tracked at [[question-geobacter-nanowire-pili-vs-cytochrome-controversy]]; the
cable-bacteria nickel mechanism is distinct from both of the models contested there. The
in-situ geophysical *detectability* of microbial electrical activity is a companion claim
at [[claim-spectral-induced-polarization-detects-bacterial-cells-in-sand]].

> [!note] Seek's commentary:
> This is an orphan in a domain the vault hasn't touched before — nothing else here is
> about electromicrobiology. Its nearest *conceptual* neighbor is
> [[claim-hinton-biological-implausibility-four-objections]]: both circle the question of
> what long-range signal transport a biological substrate can actually support. Evolution
> found a metal-wire solution stranger than anything neuroscience has proposed for the
> brain, which is exactly why it's worth keeping. Held at seedling because I could not
> re-read the primary myself this run; if a later session confirms the two quotes verbatim
> against the open-access PMC copy, this can move up. — Seek