Valorization of low-cost, carbon-rich substrates by edible ascomycetes and basidiomycetes grown on liquid cultures

Three ascomycetes (Morchella vulgaris AMRL 36, M. elata AMRL 63, Tuber aestivum AMRL 364) and four basidiomycetes strains (Lentinula edodes AMRL 124 and 126, Agaricus bisporus AMRL 208 and 209) were screened for their ability to grow on liquid static flask cultures of glucose, glycerol, molasses and waste flour-rich hydrolysates with C/N ratio of 20 and produce biomass, exopolysaccharides and lipids. The profile of lipid fatty acids was also assessed. Selected strains were furthermore cultivated in C/N = 50. Results showed that substrate consumption, biomass formation and secondary metabolites production were strain, substrate and C/N ratio dependent. The maximum biomass (X), lipid (L) and exopolysaccharides (EPS) values noted were Xmax = 25.2 g/L (C/N = 20; molasses) and Lmax = 6.51 g/L (C/N = 50; rice cereal hydrolysates) by T. aestivum strain AMRL 364 and EPSmax = 2.41 g/L by M. elata strain AMRL 63 (C/N = 50; molasses), respectively. When C/N ratio of 50 was applied, biomass, lipid production and substrate consumption seem to be negatively affected in most of the trials. The adaptation and capability of the mushroom strains to be cultivated on substrates based on agro-industrial waste streams and infant food of expired shelf date offers the opportunity to set a circular oriented bioprocess.