Updated project metadata. A xylan ulitization locus in Polaribacter sp. Q13, named XUL-Q13, was predicted to be involved in mixed-linkage xylan utilization. To support this, Polaribacter sp. Q13 was cultivated separately in triplicates on mixed-linkage xylan (MX_1, MX_2, MX_3), xylose (X_1, X_2, X_3) and glucose (G_1, G_2, G_3) and their proteomes were analyzed. In addition, the proteome of the resting cells (T0) was also analyzed.