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Gene dependence is substrate- and strain-specific; no clinical microbiome threshold follows.\nexposure: Defined pectic substrates; growth media and recombinant-enzyme assays\nevidence_span: {\"source_cache\": \"artifacts/pectin-research/29255254.fulltext.txt\", \"locator\": \"Primary full-text span; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"514f1ffe2924a1c555e3ecea968fb7260d0f55aa1b22c057697dbc59676c5796\", \"start_char\": 3594, \"end_char\": 6987, \"text_sha256\": \"73cf8a91e0bec8b92fd78e4630a68e5b8f3e0fe9202fad389959e3de9259167c\"}\n[pectin-p29255254] Dietary pectic glycans are degraded by coordinated enzyme pathways in human colonic Bacteroides. 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