Fig. 5. Polysaccharide extracted from Polaribacter sp. Hel_I_88 contains high amounts of glucose in the form of α-glucan.

A Intracellular enriched extract (IC) or attached extracellular extract (EC) was subjected to acid hydrolysis (AH) and analyzed via HPAEC-PAD to determine monosaccharide composition (mol% of carbohydrate in the sample). IC was incubated with different recombinantly expressed Polaribacter sp. GH13s or Christiangramia forsetii GH16 laminarinase⁸⁸ and analyzed via (B) reducing end assay (25 μg of protein incubated with 0.5% extract solution for 24 h) or (C) FACE. Pure polysaccharide extract and extract after acid hydrolysis (AH) were used as controls. For FACE analysis, a mixture of glucose (dp1), maltose (dp2) and maltotriose (dp3) was used as standard. Values of the reducing end assay are corrected against untreated extract. All (n = 3) non-0 values are shown (dots) alongside the standard deviation (gray bar) and mean value (white line). Significance (one-sided Student’s t test) is displayed as asterisks (significant to *0.05, **0.005, ***0.0005) either directly with the bar (to samples treated with C. forsetii GH16) or at the top (to a sample containing all tested Polaribacter sp. GH13s).