(1→6)- and (1→3)(1→6)-β-glucans from Lasiodiplodia theobromae MMBJ: Structural characterization and pro-inflammatory activity

The chemical composition and structural characterization of exopolysaccharides from the fungus Lasiodiplodia theobromae MMBJ are described, and the immunomodulatory activity of a purified beta-glucan was evaluated. L. theobromae MMBJ produced three different beta-glucans. One, fraction PEPS, was a branched (1 -> 3)(1 -> 6)-beta-glucan and was insoluble in cold water. The other two, fractions SEPS-005R and SEPS-10E, were characterized as linear (1 -> 6)-beta-glucans with molar mass of 1.8 x 10(6) Da and 7.0 x 10(3) Da, respectively. From a total of 2.2 g/L of EPS produced by L theobromae through submerged fermentation, 1.5 g/L (67%) was of the branched (1 -> 3)(1 -> 6)-beta-glucan, while 25% (w/w) were linear (1 -> 6)-beta-glucans. Tests conducted with macrophages showed that the high molar mass (1 -> 6)-beta-glucan fraction (SEPS-005R) induced a pro-inflammatory response pattern. (C) 2015 Elsevier Ltd. All rights reserved.