Lipid production by Cryptococcus curvatus growing on commercial xylose and subsequent valorization of fermentation waste-waters for the production of edible and medicinal mushrooms

Abstract

A rarely studied Cryptoccus curvatus strain (viz. NRRL Y-1511) was cultivated in shake-flask submerged nitrogen-limited experiments, with commercial xylose being employed as substrate and has been proved as quite appropriate for total biomass, lipid and endopolysaccharide production. A batch bioreactor trial compared to the equivalent shake-flask experiment showed larger amounts of total lipid and biomass produced. Total dry biomass of 26.1 g/L containing c. 30 % of lipids was synthesized. Endopolysaccharides in relatively high concentrations were synthesized in the early growth stages decreasing afterwards in favor of storage lipid synthesis. Lipid production bioprocess was successfully simulated by a modified Velruyten-Aggelis model and the optimized parameter values were found to be similar to those experimentally measured. Lipids contained mostly neutral fractions (triacylglycerols) and were rich in the fatty acid Δ9C18:1, constituting a suitable starting material for the synthesis of high-quality biodiesel. Within the frame of bio-refinery, lipid fermentation waste-waters were used as maceration waters for a novel mushroom cultivation process of Pleurotus ostreatus, Lentinula edodes and Ganoderma adspersum edible and medicinal mushrooms. These waste-waters were used for first time in mushroom cultivation process demonstrating positive effect on laccase and sporophore production by these mushroom species.