Influence of Agitation and Aeration on Single Cell Oil Production by Rhodotorula glutinis from Glycerol

摘要

In the present study, the yeast Rhodotorula glutinis has been assessed with the aim of producing microbial lipids from glycerol under different aeration conditions. For such a purpose, experiments were carried out in shake flasks, under different conditions of agitation (150 to 250 rpm) and aeration (2.5 to 5.0 of flask volume-to-medium volume ratio). Furthermore, their influence on fermentative parameters (lipid and cell concentration, biomass yield; lipid yield; and lipid volumetric productivity) has been investigated using a 22 full factorial design. The statistical analysis has revealed a strong influence of both variables on substrate consumption, lipid accumulation, cell growth and lipid productivity. As a whole, results suggest that higher aeration levels provide greater cell and lipid concentrations, and lipid volumetric productivity. The best results (4.5 g/L of lipids and Q_P = 0.95 g/L-day) were achieved at the highest aeration (5.0 flask volume-to-medium volume ratio) and agitation (250 rpm) levels. Their fatty acid profile showed that oleic acid was produced in greater quantity (53.5%), followed by linoleic acid (18.7%), palmitic acid (6.8%) and stearic acid (9.9%). The microbial oil presented viscosity of 39.3 cP at 50℃ and free fatty acid content of 1.93% ± 0.08%. These are significant results and contribute to establishing operational conditions that maximize single-cell oil production from glycerol by Rhodotorula glutinis, i.e. an alternative source as renewable raw material for lipid-based biorefineries.