Using HF-MUC2-derived O-glycans from healthy versus CD HF-MUC2 (remission and active disease), as the sole carbon source for fluorescence reporter Bacteroides thetaiotaomicron-GFP (B. theta-GFP) (71), we found that O-glycans on HF-MUC2 were able to support the growth of B. theta-GFP in vitro in minimal media comparable to glucose alone (Fig. 6E), confirming the O-linked oligosaccharides from human fecal MUC2 are functional. The gene discussed is MUC2; the disease is hydrops fetalis.