Concentration of NaCl in the Growth Medium

Cells of Saccharomyces rouxii (a salt-tolerant yeast) were grown in the presence of two levels of NaCI, 0 and 15%. Mannans obtained from both the cell walls and culture filtrates (extracellular) were examined. Yields based on the dry weight of cells demonstrated that the levels of both cell wall and extracellular mannans were lower when cells were grown in the presence of 15% NaCI. However, the carbohydrate and protein contents of the mannan preparations were not altered. The cell wall mannans obtained from the two growth conditions had similar molecular weights, whereas the extracellular mannans had different molecular weight distributions. Structural analyses showed that the cell wall and extracellular mannans had similar structures. Both had an aol-6-linked backbone to which single mannose and mannobiose units were connected as side chains, predominantly by od-2 linkages. The mannans also contained mannosyloligosaccharides, mannotriose, mannobiose, and mannose attached to protein through an O-glycosidic bond. The molecular structure of the cell wall mannans remained unchanged at both levels of NaCI. However, in the presence of 15% NaCl, the side chains consisting of a mannobiose unit were slightly reduced.