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

Abstract

Background The production of microbial lipids has attracted considerable interest during the past decade since they 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 psychrophilic basidiomycetous 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 not influence the yield coefficients of both biomass and lipids production, but had positive effect on the growth rate and thus on volumetric productivity of lipid. In glucose-based media, cellular multiplication occurred first, while the lipogenic phase followed whenever the culture was limited by a nutrient other than glucose. The extent of the carbon excess had positive effects on triacylglycerols production, that was maximum with 120 g L -1 glucose, in terms of lipid concentration (19 g L -1 ), lipid/biomass (68%) and lipid/glucose yields (16%). Both glucose concentration and growth temperature influenced the composition of fatty acids, whose unsaturation degree decreased when the temperature or glucose excess increased. Conclusions This study is the first proposed biotechnological application for Rhodotorula glacialis species, whose oleaginous biomass accumulates high amounts of lipids within a wide range of temperatures through appropriate cultivation C:N ratio. Although R. glacialis DBVPG 4785 is a cold adapted yeast, lipid production occurs over a broad range of temperatures and it can be considered an interesting microorganism for the production of single cell oils.

Microbial lipid production by cold‐adapted oleaginous yeast Yarrowia lipolytica B9 in non‐sterile whey medium

“…Another reason of this decrease can be attributed to the conversion of stored lipids into citric acid, as reported by Makri et al 54 Th ese results are in good agreement with those reported by investigators, who show that incubation time strongly aff ects the cell growth and lipid accumulation in diff erent oleaginous microorganisms including the yeast Y. lipolytica. 5,49,54,55…”

“…However, there is only one report on the production of lipids by cold-adapted oleaginous yeasts, with the aim to develop a novel potential alternative feedstock for biodiesel industry. 5 Cheese whey is a green-yellowish liquid resulting from the precipitation and removal of milk casein in cheese making processes. Although several possibilities of cheese whey utilization have been explored, a major portion of the world cheese whey production is discarded as effl uent.…”

“…In non-oleaginous species, excessive carbon remains unutilized or is converted into storage polysaccharides, while, in oleaginous species, it is preferentially channeled toward lipid synthesis. 4,5 Another important factor aff ecting lipid accumulation in oleaginous yeasts is temperature. Cold-adapted yeasts (obligate psychrophilic or psychrotolerant yeasts) are characterized as micro-organisms having both high lipid content and rich unsaturated fatty acids composition.…”

“…Namely, changes in lipid metabolism of cold-adapted yeasts constitute the major adaptation of metabolic functions occurring during growth at low temperatures. [5][6][7][8][9][10] Composition of lipids is also very important for the quality of biodiesel. Saturated fatty acids (such as C16:0 and C18:0) and monounsaturated fatty acids (such as C16:1 and C18:1) are generally preferred for biodiesel were centrifuged at 5,000 rpm for 5 min.…”

Strain‐ and temperature‐dependent changes of fatty acid composition in Wickerhamomyces anomalus and Blastobotrys adeninivorans

“…The FAs C18:2(n-6), linoleic acid and C18:3(n-3), alpha-linolenic acid are essential to all higher animals. Usually, the degree of unsaturation increases Applied Biochemistry in yeasts with decreasing cultivation temperature [e.g., [7][8][9]. However, in some cases, it has also been observed that the saturation degree remained constant or even decreased at lower temperature, instead of an increase of the C16:C18 ratio that has been observed at lower temperatures [10,11].…”