Updated project metadata. Bacteroidetes have multiple polysaccharide utilization loci (PUL) which are specific for the decomposition of polysaccharides. The marine Bacteroidetes strain Flavimarina sp. Hel_I_48 encodes two separate PULs which target xylose-containing polysaccharides. We elucidated the specificity of these two PULs by correlating proteome data with biochemical activities of the encoded carbohydrate active enzymes. Proteomics revealed that one PUL targets glucuronoxylans whereas the other PUL targets arabinoxylans.