Abstract
BackgroundThe ability of some microorganisms to accumulate lipids is well known; however, only recently the number of studies on microbial lipid biosynthesis for obtaining oleochemical products, namely biofuels and some building blocks for chemistry, is rapidly and spectacularly increased. Since 1990s, some oleaginous yeasts were studied for their ability to accumulate lipids up to 60–70% of their dry weight. Due to the vast array of engineering techniques currently available, the recombinant DNA technology was the main approach followed so far for obtaining lipid-overproducing yeasts, mainly belonging to the Yarrowia lipolytica. However, an alternative approach can be offered by worldwide diversity as source of novel oleaginous yeasts. Lipogenic aptitude of a number of yeast strains has been reviewed, but many of these studies utilized a limited number of species and/or different culture conditions that make impossible the comparison of different results. Accordingly, the lipogenic aptitude inside the yeast world is still far from being fully explored, and finding new oleaginous yeast species can acquire a strategic importance.Results Holtermanniella wattica, Leucosporidium creatinivorum, Naganishia adeliensis, Solicoccozyma aeria, and Solicoccozyma terricola strains were selected as a result of a large-scale screening on 706 yeasts (both Ascomycota and Basidiomycota). Lipid yields and fatty acid profiles of selected strains were evaluated at 20 and 25 °C on glucose, and on glycerol, xylose, galactose, sucrose, maltose, and cellobiose. A variable fatty acid profile was observed in dependence of both temperature and different carbon sources. On the whole, L. creatinivorum exhibited the highest performances: total lipid yield (YL) >7 g/l on glucose and glycerol, % of intracellular lipids on cell biomass (YL/DW) >70% at 20 °C on glucose, lipid coefficient (YL/Glu) around 20% on glucose, and daily productivity (YL/d) on glucose and sucrose >1.6 g/(l*d).ConclusionsThis study provides some meaningful information about the lipogenic ability of some yeast species. Variable lipid yields and fatty acid profiles were observed in dependence of both temperature and different carbon sources. L. creatinivorum exhibited the highest lipogenic performances.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0672-1) contains supplementary material, which is available to authorized users.
Highlights
The ability of some microorganisms to accumulate lipids is well known; only recently the number of studies on microbial lipid biosynthesis for obtaining oleochemical products, namely biofuels and some building blocks for chemistry, is rapidly and spectacularly increased
The ability of some microorganisms to accumulate high intracellular amounts of lipids has been known for decades; only recently the number of studies on microbial lipid biosynthesis for obtaining oleochemical products, namely biofuels and some building blocks for lubricants, adhesives, solvents, biosurfactants, cosmetics, and degradable polymers, has rapidly and spectacularly increased, becoming a growing part of the so-called “white biotechnology” [1,2,3,4]
The 2D scatter plot reporting the correlation between estimated intracellular lipid yield (EILY) and dry weight (DW) exhibited a quite dispersed distribution of the 706 tested strains (Additional file 5: Figure S4)
Summary
The ability of some microorganisms to accumulate lipids is well known; only recently the number of studies on microbial lipid biosynthesis for obtaining oleochemical products, namely biofuels and some building blocks for chemistry, is rapidly and spectacularly increased. The ability of some microorganisms to accumulate high intracellular amounts of lipids has been known for decades; only recently the number of studies on microbial lipid biosynthesis for obtaining oleochemical products, namely biofuels and some building blocks for lubricants, adhesives, solvents, biosurfactants, cosmetics, and degradable polymers, has rapidly and spectacularly increased, becoming a growing part of the so-called “white biotechnology” [1,2,3,4]. Finding new biological sources of lipids acquires a strategic importance to reduce (or even to avoid) any competition with food resources [8, 9] In this framework, microbial lipids are among the most promising feedstock sources for oil production because their composition is quite similar to that found in most vegetable oils [10]. Taking into consideration the possibility to store big amounts of feedstock surpluses, the production of lipids via microorganisms has a lot of advantages, namely quite a simple process due to their short life cycle, no seasonal and climatic influences, and a greater ease to scale-up the process [11,12,13,14,15,16,17]
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