Are Geobacter's conductive 'nanowires' protein pili or stacked cytochromes — and did Malvankar break from Lovley's pili model?

The question

For roughly two decades, the conductive filaments ("nanowires") of Geobacter sulfurreducens have been explained by two competing structural models: Derek Lovley's lab long argued they are conductive type-IV pili (protein filaments); Nikhil Malvankar — originally trained in Lovley's group — later argued the conductive filaments are instead polymerized stacks of multiheme cytochromes (notably OmcS/OmcZ). The capture that raised this reports the dispute as still active as of ~2024, and frames it as a mentor/protégé break.

Why it matters

• It is a genuinely distinct claim from the cable-bacteria nickel-wire mechanism (claim-cable-bacteria-conduct-through-nickel-protein-wire) — a different organism and a different pair of candidate mechanisms — and worth its own claim-note if it can be sourced properly.
• It is a recurring vault-resonant pattern: a scientific-priority / attribution dispute running through named people, close kin to the credit-and-attribution threads already in the vault.
• Resolving it would let the vault state cleanly which conduction mechanisms are established versus contested across electromicrobiology.

Why it is a question and not yet a claim-note

The capture sourced this dispute only to secondary coverage (Scientific American, Frontiers in Microbiology summaries) — Tier 3. Attributing specific, opposed scientific positions to named researchers is a contested claim, and the sourcing floor (00-meta/specs/sources.md) requires escalation to Tier 1–2 for contested attribution. No direct quotes from Malvankar or Lovley, and no specific primary paper, were captured. Promoting it as a claim-note now would rest a contested attribution on a soft-for-truth source.

What would answer it

• Malvankar et al. cryo-EM / structural papers on OmcS/OmcZ cytochrome filaments (e.g. Cell 2019 and follow-ups) — read the primary for their own framing of the filament's identity.
• Lovley-lab primary papers stating the conductive-pili model in their own words.
• A recent (2023–2024) review or head-to-head primary confirming the dispute is still unresolved, and pin down whether the "broke from his mentor" narrative is accurate or a secondary-source simplification.

Routed from the promotion of 10-inbox/raw/2026-07-09-hop-cable-bacteria-nickel-wire (2026-07-11) — a "further lead" the capture itself flagged as deserving its own note.

Progress log

• Answered 2026-07-25 by the promotion of the follow-up capture 2026-07-16-are-geobacters-conductive-nanowires-protein-pili-or-stacked.md, which sourced the dispute to Tier 1 primaries this question's 'What would answer it' list called for. Structural identity: claim-geobacter-conductive-filaments-are-omcs-cytochrome-polymers and claim-geobacter-pili-are-secretory-pseudopili-not-nanowires establish the current leading model — the conductive filaments are OmcS/OmcZ cytochrome polymers, and the PilA pili are secretory pseudopili, not nanowires. Original model: claim-lovley-2005-proposed-geobacter-nanowires-are-conductive-pili. The 'break': claim-malvankar-lab-overturned-pili-model-without-lovley settles the second half on the publication record (Malvankar's 2019/2021 structures exclude Lovley; Lovley kept defending e-pili in mBio 2022) while flagging the 'personal falling-out' framing as unsourced interpretation. Residual: the dispute is not physically closed — claim-2024-paper-disputes-geobacter-cytochrome-nanowire-conductivity reopens whether the cytochrome nanowires' measured conductivities are consistent with their structures; that narrower, load-bearing verification is now carried by question-verify-guberman-pfeffer-2024-cytochrome-nanowire-conductivity-inconsistency rather than by leaving this question open.