Single cell oils of the cold-adapted oleaginous yeast Rhodotorula glacialis DBVPG 4785

Background: The production of microbial lipids has attracted considerable interest during the past decade sincethey can be successfully used to produce biodiesel by catalyzed transesterification with short chain alcohols.Certain yeast species, including several psychrophilic isolates, are oleaginous and accumulate lipids from 20 to 70%of biomass under appropriate cultivation conditions. Among them, Rhodotorula glacialis is a psychrophilicbasidiomycetous species capable to accumulate intracellular lipids.Results: Rhodotorula glacialis DBVPG 4785 is an oleaginous psychrophilic yeast isolated from a glacial environment.Despite its origin, the strain abundantly grew and accumulated lipids between -3 to 20°C. The temperature did notinfluence the yield coefficients of both biomass and lipids production, but had positive effect on the growth rateand thus on volumetric productivity of lipid. In glucose-based media, cellular multiplication occurred first, while thelipogenic phase followed whenever the culture was limited by a nutrient other than glucose. The extent of thecarbon excess had positive effects on triacylglycerols production, that was maximum with 120 g L-1 glucose, interms of lipid concentration (19 g L-1), lipid/biomass (68%) and lipid/glucose yields (16%). Both glucoseconcentration and growth temperature influenced the composition of fatty acids, whose unsaturation degreedecreased when the temperature or glucose excess increased.Conclusions: This study is the first proposed biotechnological application for Rhodotorula glacialis species, whoseoleaginous biomass accumulates high amounts of lipids within a wide range of temperatures through appropriatecultivation C:N ratio. Although R. glacialis DBVPG 4785 is a cold adapted yeast, lipid production occurs over a broadrange of temperatures and it can be considered an interesting microorganism for the production of single cell oils.