Rhamnose is a sugar described as a plant cell wall component, and it appears in this corpus both as a genomic pathway marker and as a candidate prebiotic substrate 1,2. Source tables refer to it as “Rhamnose” and, in gap listings, as “Rhamnose utilization” 3.
Candidate selective prebiotic in consortium design
In the cystic fibrosis formulation-design project, the rhamnose row reports 1% pathway completeness for Pseudomonas aeruginosa (PA) against 100% completeness in neisseria mucosa (N. mucosa) and gemella sanguinis (G. sanguinis), with a reported selectivity of 0.99 2.
That selectivity is a genomic prediction, not an observed growth result. The project’s rationale frames the candidates as “100% commensal pathway completeness vs 0% PA” and states explicitly that the prediction “must be validated experimentally”; the same report’s Section 2.11 is narrower, giving PA fucose and rhamnose completeness as 1% and tying other candidates to single carriers (xylitol completeness 98% in Streptococcus salivarius) 2.
The wider claim — that genomic pathway comparison yields sugar alcohol prebiotics as a strategy “qualitatively different from amino acid supplementation” — is therefore a hypothesis rather than a demonstrated result: growth selectivity remains untested, each candidate pathway occurs in only 1–2 core species, xylitol completeness is 98% in Streptococcus salivarius, and PA fucose and rhamnose completeness is 1% 2. See computational-pathway-prediction-validation and competitive-exclusion-consortium-design.
Pathway completeness across Pseudomonas
In the Pseudomonas carbon-ecology project, within a subgenus-level comparison (Pseudomonas sensu stricto versus Pseudomonas_E species), “rhamnose and fucose are more complete in P. aeruginosa (66.8%) than P. fluorescens group (41.3% and 45.1% respectively), though this difference was not statistically significant after FDR correction” — FDR (false discovery rate) correction being the multiple-testing adjustment applied across the pathway comparisons 1. The contrast is thus a null result at the resolution available, not a demonstrated clade difference, and the figure is reported inside a group-level analysis rather than as a standalone species-level completeness value 1.
Rhamnose nevertheless carried weight as a predictive feature: among the top environment-classifier pathways it ranked third with importance 0.086, behind D-serine (0.132, associated with rhizosphere niches) and arabinose (0.094), and ahead of fucose (0.085) and xylose (0.070) 1.
Utilization gaps in fitness-data organisms
Rhamnose utilization is listed as a carbon-source gap in 31 organisms, with Marinobacter, P. putida and Phaeo given as examples 3. Such gaps are candidates for the prioritization logic discussed in experimental-prioritization-of-functional-dark-matter.
Tensions
Within cf_formulation_design, the rationale’s blanket “100% commensal pathway completeness vs 0% PA” does not match the project’s own per-pathway numbers, which give PA rhamnose completeness as 1% and 100% completeness only for N. mucosa and G. sanguinis 2. The report does not explain the inconsistency between the 0% framing and the 1% table value, so it is recorded here as an unresolved internal discrepancy and is not averaged or reconciled.
Across projects, the two reports characterise PA differently: cf_formulation_design treats near-absent rhamnose capability in PA (1%) as the basis for selectivity, while pseudomonas_carbon_ecology reports rhamnose completeness in P. aeruginosa at 66.8% inside a subgenus-level comparison whose difference from the P. fluorescens group did not survive FDR correction 2,1. Neither source addresses the other, and neither states why the values differ; differences in genome panel, aggregation level or completeness definition are only hypotheses, untested in this corpus. The discrepancy is left open: settling which value applies to a clinical formulation would require a recomputation of rhamnose pathway completeness on a single declared genome set.
Related pages
- computational-pathway-prediction-validation — rhamnose selectivity is a genomic prediction that “must be validated experimentally” 2
- null-results-under-limited-statistical-resolution — the P. aeruginosa versus P. fluorescens group rhamnose/fucose contrast was not significant after FDR correction 1
- metabolic-capacity-specialization — rhamnose ranked third (importance 0.086) among environment-classifier pathways 1
- fucose, xylitol, xylose, arabinose — sugars tabulated alongside rhamnose in these projects 2,1