Effect of temperature on growth and lipid production of the cold-adapted Rhodotorula glutinis strains

Abstract

Cold-adapted oleaginous yeasts are excellent lipid-producers and they are considered as a potential source of triglycerides (TAG) for the biodiesel synthesis. The lipogenesis is influenced by temperature. This work evaluated the effect of different temperatures on the growth and lipids accumulation by two strains of Rhodotorula glutinis (R4 and R48). Yeasts were cultured (168 h, 250 rpm) at 15, 20 and 25°C in nitrogen-limited glucose-based medium (MI). An increase of biomass, lipid production and total lipids content was observed along the culture time for the yeasts at the three incubation temperatures. The highest biomass (11.48-13.53 g L-1) was yielded after 72 h at 20 and 25°C and remained constant until the end of the culture. At 15°C the growth was slower for both strains. Effects of temperature on lipid production and accumulation were more pronounced in R48 strain. The highest values of these parameters were reached at 20° C (5.64 g L-1; 45.74) and 25°C (5.48 g L-1; 49.15%) after 120 h of culture. While at 15 °C results were lower. R4 was less affected by temperature and significant differences were not observed. The higher lipid production (5.68-7.00 g L-1) and lipids accumulation (48.02-53.00%) were yielded after 120 h. The presence of TAG in microbial lipids was determined qualitatively using thin layer chromatography (TLC). The results showed that these yeasts are able to synthesize TAG under the culture conditions tested. Qualitatively, there was an increase in the production of TAG (larger size and density of spots) with temperature. The fatty acids profile determined by GC-FID is suitable for biodiesel synthesis. R4 and R48 are interesting yeasts for microbial oils production and they are capable to grow and produce lipids between 15 and 25°C.