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Rhamnogalacturonan I is a recalcitrant pectin domain during Clostridium thermocellum-mediated deconstruction of switchgrass biomass

ABSTRACT: The amounts of hemicellulosic and pectic polysaccharides, two complex cell wall glycans that contribute to plant biomass recalcitrance and that are partially solubilized during CBP of switchgrass aerial biomass by Clostridium thermocellum were evaluated in the liquor, solid residues and residue washate recovered during a 120-h CBP process. After 120 h, 24% of milled switchgrass was solubilized in the C. thermocellum CBP platform. Higher concentrations of arabinose, xylose, galactose, and glucose accumulated in the CBP-fermentation liquor and washate compared to fermentation controls without C. thermocellum, indicating that C. thermocellum solubilized hemicelluloses, but did not fully metabolize them. After five days of fermentation, the relative amount of rhamnose in the solid residues increased by 16% compared to controls, and CBP solid residues had more than 23% increased reactivity against RG-I reactive monoclonal antibodies, indicating that the pectic polymer rhamnogalacturonan I (RG-I) was not effectively solubilized from switchgrass biomass by C. thermocellum CBP. Similarly, the amount of mannose (Man) in the CBP solid residues increased by 7% and reactivity against galactomannan reactive antibodies increased by greater than 14%,indicating that the hemicellulosic polymer galactomannan was also resistant to degradation by C. thermocellum during CBP fermentation.

INSTRUMENT(S): Q Exactive Plus

ORGANISM(S): Panicum Virgatum (ncbitaxon:38727)

SUBMITTER: Paul Abraham

PROVIDER: MSV000100953 | MassIVE | Tue Feb 24 09:42:00 GMT 2026

REPOSITORIES: MassIVE

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Rhamnogalacturonan I is a recalcitrant pectin domain during Clostridium thermocellum-mediated deconstruction of switchgrass biomass

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