Fig. 4. Specific upregulation of pathways involved in brown algae carbohydrate catabolism during the utilization of fresh brown algal tissues.
A Heatmap of the 51 PULs identified in the genome of Z. galactanivorans DsijT. PUL 1 to 50 were identified during the annotation of the Z. galactanivorans DsijT genome by the presence of the susCD-like pair, their boundaries are based on bioinformatic predictions (Supplementary Table S3 in [42]). PUL51 targeting 3,6-anhydro-D-galactose and involved in carrageenan catabolism (but lacking the susCD-like pair) was further described [25]. For each PUL, the mean log2FC of all genes is represented, taking maltose as a control condition. Carbon sources and PULs were arranged according to a hierarchical clustering analysis (Ward’s method). A PUL was considered regulated (induced in red, repressed in blue) if more than 50% of the genes were significantly differentially expressed (*) and strongly regulated if more than 80% of the genes were significantly differentially expressed (**). Putative substrates targeted by the PULs are indicated. Hash signs denote PULs biochemically characterized previously in Z. galactanivorans (##) or in another organism (#). B Heatmap representing the log2FC of individual genes contained in the PULs induced with macroalgae and which clustered together in A. C Activity of extracellular polysaccharidases collected in the microcosms containing macroalgae after 65 h. The mean value measured in the uninoculated controls was subtracted from each value. Bars are means of independent replicates (n = 2 or 3) shown as individual points. Significant difference from zero was tested when n = 3 (t-test; *p < 0.05). L. dig: Laminaria digitata; F. ser: Fucus serratus; A. nod: Ascophyllum nodosum; FCSP: fucose-containing sulfated polysaccharide; PS: Polysaccharide.