Oleaginous yeasts- substrate preference and lipid productivity: a view on the performance of microbial lipid producers

Abstract

Background Oleaginous yeasts are promising microbial platforms for sustainable, bio-based production of biofuels and oleochemical building blocks. Bio-based residues provide sustainable and cost-effective carbon sources for fermentative yeast oil production without land-use change. Considering the regional abundancy of different waste streams, we chose complex biomass residue streams of marine origin; macroalgae hydrolysate, and terrestrial origin; wheat straw hydrolysate in the presence, and absence of corn steep liquor as a complex nitrogen source. We investigated the biomass and lipid yields of an array of well-described oleaginous yeasts; R. glutinis, T. asahii, R. mucilaginosa, R. toruloides, C. oleaginosus growing on these hydrolysates. Furthermore, their sugar utilization, fatty acid profile, and inhibitory effect of the hydrolysates on yeast growth were compared. For correlative reference, we initially performed comparative growth experiments for the strains on individual monomeric sugars separately. Each of these monomeric sugars was a dominant carbon source in the complex biomass hydrolysates evaluated in this study. In addition, we evaluated N-acetylglucosamine, the monomeric building block of chitin, as a low-cost nitrogen and carbon source in yeast fermentation. Results C. oleaginosus provided the highest biomass and lipid yields. In the wheat straw and brown algae hydrolysates, this yeast strain gained 7.5 g/L and 3.8 g/L lipids, respectively. Cultivation in algae hydrolysate resulted in a higher level of unsaturated fatty acids in the lipids accumulated by all yeast strains. R. toruloides and C. oleaginosus were able to effectively co-utilize mannitol, glucose, and xylose. Growth rates on wheat straw hydrolysate were enhanced in presence of corn steep liquor. Conclusions Among the yeast strains investigated in this study, C. oleaginosus proved to be the most versatile strain in terms of substrate utilization, productivity, and tolerance in the complex media. Various fatty acid profiles obtained on each substrate encourage the manipulation of culture conditions to achieve the desired fatty acid composition for each application. This could be accomplished by combining the element of carbon source with other formerly studied factors such as temperature and oxygen. Moreover, corn steep liquor showed promise for enhancement of growth in the oleaginous strains provided that carbon substrate is available.

Adaptation of Proteome and Metabolism in Different Haplotypes of Rhodosporidium toruloides during Cu(I) and Cu(II) Stress

“…Briefly, biomass was converted into fatty acid methyl ester (FAME) by MultiPurposeSampler MPS robotic (Gerstel, Linthicum Heights, MD, USA). FAMEs were analyzed by gas chromatography (GC-2025 coupled to an AOC-20i auto-injector and an AOC-20s auto-sampler, Shimadzu, Duisburg, Germany) and a flame ionization detector [ 20 ]. A Zebron ZB-wax column (Phenomenex, Aschaffenburg, Germany) was used for separation.…”

Mastering targeted genome engineering of GC-rich oleaginous yeast for tailored plant oil alternatives for the food and chemical sector

“…Its superiority over other oleaginous microorganisms in having high triglyceride (TAG) content, substrate flexibility, and rapid growth rate has made this yeast a prime candidate for oleochemical production [5][6][7]. To date, C. oleaginosus has displayed the highest carbon source flexibility linked with high de-novo oil productivity and yield of any oleaginous yeast strain [7][8][9][10][11][12][13]. Moreover, compared to other yeasts, C. oleaginosus is highly resistant to fermentation inhibitors (including weak organic acids e.g.…”

Screening of xylose utilizing and high lipid producing yeast strains as a potential candidate for industrial application

“…Only a small fraction of the known yeast species are oleaginous, and only about 5% of those have been reported to accumulate over 25% lipids [ 8 ]. Species known to accumulate lipids include Trichosporon asahii, Cutaneotrichosporon oleaginosus, Y. lipolytica, as well as the red yeasts Rhodotorula glutinis, Rhodotorula mucilaginosa, Rhodosporidium toruloides, and some Candida species [ 2 , 8 , 9 ]. Both R. glutinis and R. toruloides are well-studied yeasts able to utilize pentose sugars [ 10 – 14 ].…”