Oleaginous yeasts for biochemicals, biofuels and food from lignocellulose‐hydrolysate and crude glycerol

Abstract

Microbial lipids produced from lignocellulose and crude glycerol (CG) can serve as sustainable alternatives to vegetable oils, whose production is, in many cases, accompanied by monocultures, land use changes or rain forest clearings. Our projects aim to understand the physiology of microbial lipid production by oleaginous yeasts, optimise the production and establish novel applications of microbial lipid compounds. We have established methods for fermentation and intracellular lipid quantification. Following the kinetics of lipid accumulation in different strains, we found high variability in lipid formation even between very closely related oleaginous yeast strains on both, wheat straw hydrolysate and CG. For example, on complete wheat straw hydrolysate, we saw that one Rhodotorula glutinis strain, when starting assimilating D‐xylosealso assimilated the accumulated lipids, while a Rhodotorula babjevae strain could accumulate lipids on D‐xylose. Two strains (Rhodotorula toruloides CBS 14 and R. glutinis CBS 3044) were found to be the best out of 27 tested to accumulate lipids on CG. Interestingly, the presence of hemicellulose hydrolysate stimulated glycerol assimilation in both strains. Apart from microbial oil, R. toruloides also produces carotenoids. The first attempts of extraction using the classical acetone‐based method showed that β‐carotene is the major carotenoid. However, there are indications that there are also substantial amounts of torulene and torularhodin, which have a very high potential as antioxidants.

From straw to salmon: a technical design and energy balance for production of yeast oil for fish feed from wheat straw

“…Using forest residues such as branches and tops in regions with good availability would increase the amount of biomass available for yeast oil production, and ongoing laboratory studies by our research groups and others show promising results for Rhodotorula spp. fed with wood hydrolysate ([ 58 ], unpublished results). Although yeast oil was shown to perform better than ordinary vegetable oil in terms of PED fossil in this study, there is a risk that this production method, if implemented on a large scale, soon would face similar sustainability issues as the crop production it replaced.…”

Mushrooms for enhanced agriculture sustainability – the MUSA concept

“…However, SMS should be considered a promising source of valuable products and starting material for several uses rather than valueless waste (Leong et al, C3-BIOECONOMY, Revista de Investigación y Transferencia en Bioeconomía Circular y Sostenible Nº4 (2023) 2022). Recent publications show that SMS is a potential source of feed, food, bioactive compounds, biofuels, and enzymes, and it can be used as a biofertilizer, soil amendment, bioremediation agent, and several other uses (Martín et al, 2023). Valorization of SMS is crucial for the sustainability of the mushroom industry.…”

“…The current project intends to assess the fermentability of SMS hydrolysates with oleaginous yeasts. We have previously cultivated oleaginous yeasts in hydrolysates of other lignocellulosic materials (Passoth et al, 2023), and we expect that SMS hydrolysates will also be suitable substrates.…”

Enhanced glycerol assimilation and lipid production in Rhodotorula toruloides CBS14 upon addition of hemicellulose primarily correlates with early transcription of energy-metabolism-related genes

“…Microbial oils have the potential to replace VO in the production of biodiesel and feed and food additives [7,8]. Oleaginous yeasts are known to be among the fastest lipid producers on earth [9][10][11]. Among these, Rhodotorula species, which are basidiomycetes oleaginous yeasts, can convert a variety of industrial low-value residues, such as lignocellulose hydrolysates, including hemicellulose from pulp-and-paper industry or crude glycerol, a residue from biodiesel production, into lipids and carotenoids [11][12][13][14][15][16][17].…”

“…Oleaginous yeasts are known to be among the fastest lipid producers on earth [9][10][11]. Among these, Rhodotorula species, which are basidiomycetes oleaginous yeasts, can convert a variety of industrial low-value residues, such as lignocellulose hydrolysates, including hemicellulose from pulp-and-paper industry or crude glycerol, a residue from biodiesel production, into lipids and carotenoids [11][12][13][14][15][16][17]. In a recent study, we could show that lipid production rate was increased in Rhodotorula species when cultured on crude glycerol and hemicellulose hydrolysate (CGHH), compared to crude glycerol (CG) as the sole carbon source [13].…”