Adaptation of Volvariella volvacea metabolism in high carbon to nitrogen ratio media

Abstract

Increasing glucose concentration (up to 46%) in the culture medium of Volvariella volvacea resulted in a noticeable biomass increase (63.82%) and intracellular polysaccharide (IPS) production (32.84% in absolute and 51.34% in relative values). In high glucose concentrations, decreased biomass yields on glucose consumed were recorded. A non-negligible lipid was synthesized (up to 32.22%, w/w) in the first growth steps. Lipids and IPS were decreased as fermentation proceeded. Fatty acid composition of lipids was not remarkably affected by the C/N ratio imposed, whereas the concentration of neutral lipids increased in the high C/N ratio media. Phospholipid was the richest in saturated fatty acids lipid fraction. The major phospholipid classes, i.e. phosphatidyl-choline and phosphatidyl-inositol, were differentially affected by the high glucose concentrations, as the former increased its proportion and the latter decreased. Linoleic was the predominate fatty acid. C/N ratio and fermentation time affected IPS composition, as glucose increased in a high C/N ratio, while fructose and mannitol decreased.

Keywords: Biomass; Fungi; Glucose; Lipids; Polysaccharides.