Bound cellulose-methane formate use and product-removal feedback #1326

Source-based self-adversarial finding

Record: kb/communities/Clostridium_Cellulovorans_Methanosarcina_Cellulose_Methane_Coculture.yaml (CommunityMech:000174). Reviewed at db05129c5f8a9fb47b6ed716405dce1be845a207 against PMID:28191038, full primary main body.

The existing graph omits important constraints: M. barkeri did not grow with formate alone after nine months; a mixed-substrate monoculture consumed only a small fraction of supplied formate; the substantial formate/acetate depletion is coculture-specific. Gas/product measurements and RT-qPCR support the authors' conceptual pathways, not direct tracing of each substrate's electron contribution.

The feedback arrow/node also present VFA depletion as a unique mediator of pH stabilization and improved cellulose degradation. The paper reports both substrate consumption and a changed fermenter production pattern. Butyrate/lactate were lower but not net-depleted; improved cellulose degradation did not significantly increase C. cellulovorans cell density or growth yield. MUTUALISM overstates reciprocal measured fitness.

Acceptance

• Retain measured cellulose-to-methane conversion, substrate depletion and both existing arrows with appropriate certainty.
• Bound formate use to the tested conditions, preserve negative and mixed-substrate controls, and distinguish conceptual pathways from resolved flux.
• Explain the M. barkeri-to-fermenter direction as product-removal feedback, not reverse substrate donation.
• Qualify pH/product-removal mediation, preserve changed fermentation and unchanged fermenter growth, remove categorical mutualism, add a gap/tests/history.

Whole record, primary Background/Methods/Results/Discussion/Conclusions, main table and six main figure captions read. No visual image/supplement inspection claimed. Dedup: all 665 issue titles/bodies plus ignored/hidden local review/history/research/test files. #965 is a different methane-panel acetate-exchange issue.