Fig. 6
HPAEC chromatogram (a) and direct infusion ESI–MS analysis (b, c) of deacetylated chito-oligosaccharides (CHOS) obtained upon incubating L. plantarum cells harboring pSIP_1261CsnA (b) or pSIP_CsnAcwa2 (c) with chitosan. The HPAEC chromatograms include a negative control (pEV) and a substrate blank containing chitosan without addition of cells. Standards for deacetylated oligomers are not easily accessible. It is known from earlier work [37] that chitosan oligomers elute between 7 and 14 min, as is observed; the presence of such oligomers was confirmed by MS analysis. The MS-spectra show deacetylated CHOS from DP 2 to DP 6 {[M + H]+: m/z 341 (DP2), 502 (DP3), 663 (DP4), 824 (DP5), 985 (DP6); and double charged species of the same compounds; [M + 2H]2+: m/z 251 (DP3), 332 (DP4), 412 (DP5), 493 (DP6)}