Structural modification of cell wall mannans of Candida albicans serotype A strains grown in yeast extract-Sabouraud liquid medium under acidic conditions.

The cell wall mannans of two Candida albicans serotype A strains, NIH A-207 and J-1012 (abbreviated as A and J strains, respectively), cultured in yeast extract-Sabouraud liquid medium at pH 2.0, contained neither a phosphate group nor a beta-1,2-linked mannopyranose unit (H. Kobayashi, P. Giummelly, S. Takahashi, M. Ishida, J. Sato, M. Takaku, Y. Nishidate, N. Shibata, Y. Okawa, and S. Suzuki, Biochem. Biophys. Res. Commun. 175:1003-1009, 1991). In this study, the mannans obtained from A and J strains grown in pH 2.0 medium (abbreviated as mannans A2 and J2, respectively) exhibited quite different reactivities against rabbit anti-C. albicans and anti-Saccharomyces cerevisiae sera compared with those of mannans from the corresponding strains cultured in conventional medium at pH 5.9 (abbreviated as mannans A and J, respectively). Namely, mannans A2 and J2 lost reactivity against the former serum but reacted with the latter serum to a higher extent than mannans A and J. In order to account for these difference in more detail, mannans A2 and J2 were subjected to acetolysis. Elution profiles of the acetolysates were completely different from those of acetolysates obtained from mannans A and J reported in our previous papers. The 1H nuclear magnetic resonance spectra of the oligosaccharides from mannans A2 and J2 obtained by this procedure indicate that the side chains are composed of alpha-linked mannopyranose units densely linked to the alpha-1,6-linked backbone. The long side chains containing one alpha-1,3-linked mannopyranose unit are markedly increased.