Production of lipid from depolymerised lignocellulose using the biocontrol yeast, Rhodotorula minuta: The fatty acid profile remains stable irrespective of environmental conditions

The oleaginous yeast Rhodotorula minuta has been used previously as a biocide agent and for the production of β-carotene. In addition, R. minuta has been shown to produce up to 40% lipids, while demonstrating a faster growth rate than the similar oleaginous yeasts; Lipomyces starkeyii and Rhodotorula glutinis. In this study this promising yeast was evaluated for its potential to produce glyceride lipids under the harsh conditions and complex sugar mixtures produced from depolymerised lignocellulose. The fatty acid profile of R. minuta was not found to change significantly irrespective of the environmental conditions and contained approximately 20% palmitic acid, 5% stearic acid, 60% oleic acid and 15% linolenic acid. R. minuta was found to grow on a range of sugars, and could consume xylose and glucose when both sugars were present, however, R. minuta was found to be highly sensitive to inhibitors, such as furfurals and organic acids, formed under the harsh lignocellulose depolymerisation conditions. Accordingly R. minuta did not grow well on biomass depolymerised with an acid pre-treatment stage. However, R. minuta was cultured successfully on food waste depolymerised with no additional acids, producing up to 19 g /L cell mass with a lipid content of up to 25% of the dry cell weight.