How Fine Structural Differences of Xylooligosaccharides and Arabinoxylooligosaccharides Regulate Differential Growth of Bacteroides Species.

Xylooligosaccharides (XOS) and arabinoxylooligosaccharides (AXOS) could be used to selectively favor growth of certain gut bacterial groups. The objective of this research was to understand how the structural differences of XOS and AXOS influenced the growth of Bacteroides species commonly found in the intestine. We report that the specific structural details of XOS and AXOS dictate the differential growth of Bacteroides species in the intestine. We also investigated the expression of two polysaccharide utilization loci (PULs) in a strain of Bacteroides ovatus upon growth on AXOS using three different susC transcripts as sentinel reporter genes. 23-α-l-Arabinofuranosyl-xylotriose (A4) was shown to upregulate small xylan PUL gene expression, while 23,33-di-α-l-arabinofuranosyl-xylotriose (A6) decreased expression of this PUL. These results reveal new details about the potentially very specific structure-function relationship of XOS and AXOS that could be used in targeted alteration of the microbial population in the gut through dietary interventions to maintain health.