P levan

Bacteroides strains were cultured anaerobically to stationary phase in TYG and diluted 1:200 into pre-reduced minimal media containing glucose (G8250, MilliporeSigma), galactose (G0750, MilliporeSigma), fructose (F0127, MilliporeSigma), arabinose (A3256, MilliporeSigma), xylose (X1500, MilliporeSigma), chondroitin sulfate (C9819, MilliporeSigma), heparin (MilliporeSigma, H4784), hyaluronic acid (MilliporeSigma, 53747), levan (P-LEVAN, Megazyme), or inulin (P-INUL, Megazyme) where indicated in pre-reduced 96-well or 384-well clear microplates (Corning). To remove free fructose from inulin, a 1% inulin solution was passed over a ZebaSpin de-salting column (ThermoFisher) prior to the addition of cultures. Kinetic absorbance measurements were taken at 600 nm every 15 min for 96 h using a Tecan Infinite M-plex maintained at 37 °C in a Coy anaerobic chamber with a 2.5% hydrogen atmosphere.

Bt and Bo strains were cultured in TYG containing 2 µg/mL tetracycline overnight before being diluted 50-fold into minimal media containing 0.5% galactose anaerobically grown to mid-exponential phase at 37 °C (approximately 4 h). Cultured cells were pelleted by centrifugation before the supernatant was removed, and cells were resuspended in 2X minimal media lacking a carbon source. Equal volumes of each cell suspension were transferred to a pre-reduced, white, clear bottom 384-well microplate (Corning 3765) containing equal volume of following polysaccharides: chondroitin sulfate (MilliporeSigma, C9819), heparin (MilliporeSigma, H4784), hyaluronic acid (MilliporeSigma, 53747), levan (Megazyme, P-LEVAN), or inulin (Megazyme, P-INUL) where indicated. Absorbance at 600 nm and luminescence were measured every 15 min for 18 h using a Tecan Infinite M-Plex instrument anaerobically at 37 °C temperature. RLU were calculated as luminescence values divided by absorbance at 600 nm and normalized to identical measurements from each strain supplied only galactose.