Fig. 3. Phytoplankton bloom associated bacteria encode a multitude of α-glucan-degrading enzymes.

A Maximum likelihood tree of the main GH13s encoded in the α-glucan PULs of 53 bloom-associated flavobacterial isolates as well as PUL-associated GH13s from the top 50 expressed MAGs of the 2020 Helgoland spring bloom¹⁷. Groups are clustered for clarity with arrows indicating group size. Numbers under the enzyme descriptions represent the number of sequences in the group with the included number of MAG-associated sequences in parenthesis. Colored arrows correspond to (B) characterization of representative Polaribacter sp. Hel_I_88 GH13 enzymes. 25 μg protein were incubated with 0.5% poly- or oligosaccharide for 24 h. Shown are all non-0 values (dots) with standard deviation (bars) and mean (white lines) activity of recombinantly produced enzyme on different oligo- and polysaccharides measured via DNS-assay (all values corrected against oligo-/polysaccharide without enzyme, n = 3). Significance to controls containing laminarin with enzyme is indicated by asterisks above the respective bars (one-sided Student’s t test, significant to *0.05, **0.005, ***0.0005). M Maltose, M3 Maltotriose, IM3 Isomaltotriose, Pan Panose, IPan Isopanose, M5 Maltopentose, α-cyc α-Cyclodextrin, β-cyc β-Cyclodextrin, Pul Pullulan, Gly Glycogen, Dex Dextrin, Lam Laminarin. See also Supplementary Fig. S5 for corresponding degradation patterns investigated via FACE and TLC.