Fig. 7
Characterization of the biosurfactant (YG) produced by Rhodotorula babjevae YS3 with glucose as the sole carbon source using LC–MS in positive electrospray ionization mode (+ESI). a MS showing the sodiated adducts of lactonic sophorolipids (LS) with pentadecatrienoic (C15:3) and octadecadienoic (C18:2) lipid side chains at m/z values 581 and 625 respectively, while the adduct ion at m/z 713 represents di-acetylated lactonic sophorolipid (Ac2LS) with octadecanoic (C18) lipid chain. b The ion at m/z 579 corresponds to lactonic sophorolipid with hexadecanoic lipid chain (LS-C16). c Disodiated adduct ion of the fragmented tridecenoic fatty acid side chain was observed at m/z 257, the protonated ion at m/z 374 represents the acidic sophorolipid with tridecenoic acidic chain (AS-C13:1) after loss of the terminal hexose (C6H11O6) from the sophorose disaccharide, sodiated adduct of fragmented mono-acetylated disaccharide moiety (AcSophorose) was observed at m/z 407. d The protonated ions at m/z 285 and 535 represent fragmented octadecanoic fatty acid side chain and lactonic sophorolipid with tridecenoic lipid chain (LS-C13:1) respectively; the sodiated adduct of fragmented di-acetylated sophorose moiety (Ac2Sophorose) was observed at m/z 449. e The sodiated adducts of the fragmented sophorose moiety and the acidic sophorolipid with undecanoic acidic side chain (AS-C11) were observed at m/z 365 and 549 respectively