Structural elucidation of the exopolysaccharide produced by the mangrove fungus Penicillium solitum.

•Exopolysaccharide GW-12 was obtained from mangrove fungus Penicillium solitum.•GW-12 was a mannan with branches and its molecular weight was about 11.3kDa.•Backbone of GW-12 consisted of (1→2)-α-d-Manp and (1→6)-α-d-Manp.•Main chain was branched by single α-d-Manp at C-6 position of (1→2)-α-d-Manp.