High-value Lipids Research Articles

Mechanistic insights into lipid extraction from wet microalgae using hydrophobic deep eutectic solvents under hydrothermal conditions

Hydrophobic deep eutectic solvents (HDESs) were first employed under hydrothermal conditions to form a two-phase system for instantaneous and efficient lipid extraction from wet microalgae, preventing lipid degradation and avoiding the use of toxic solvents. Ten HDESs were assessed for their efficiency and selectivity in lipid extraction. Among them, OCT-DEC, composed of octanoic acid and decanoic acid, achieved the highest extraction efficiency at 95.42 %, while also preventing the co-extraction of proteins and reducing sugars. Molecular dynamics simulations revealed that lipid extraction efficiency is primarily influenced by lipid-HDES interactions, which drive lipid diffusion, and the interfacial properties of the two-phase hydrothermal system, which resist lipid diffusion. The superior performance of OCT-DEC is attributed to its high hydrogen bond density and short bond lifetimes, which, combined with its structural stability, synergistically reduce resistance to lipid diffusion at the interface. Additionally, OCT-DEC significantly enhances the thermal stability of unsaturated fatty acids, such as C20:5, effectively preventing the degradation of high-value lipids and highlighting its potential for hydrothermal extraction of these valuable compounds.

Implicating the red body of Nannochloropsis in forming the recalcitrant cell wall polymer algaenan

Stramenopile algae contribute significantly to global primary productivity, and one class, Eustigmatophyceae, is increasingly studied for applications in high-value lipid production. Yet much about their basic biology remains unknown, including the nature of an enigmatic, pigmented globule found in vegetative cells. Here, we present an in-depth examination of this “red body,” focusing on Nannochloropsis oceanica. During the cell cycle, the red body forms adjacent to the plastid, but unexpectedly it is secreted and released with the autosporangial wall following cell division. Shed red bodies contain antioxidant ketocarotenoids, and overexpression of a beta-carotene ketolase results in enlarged red bodies. Infrared spectroscopy indicates long-chain, aliphatic lipids in shed red bodies and cell walls, and UHPLC-HRMS detects a C32 alkyl diol, a potential precursor of algaenan, a recalcitrant cell wall polymer. We propose that the red body transports algaenan precursors from plastid to apoplast to be incorporated into daughter cell walls.

Comparison of different small-scale cultivation methods towards the valorization of a marine benthic diatom strain for lipid production

Marine benthic diatoms have the capacity to produce quality biomass and bioactive compounds for various commercial applications. Amphora sp. NCC169 is one of such species that have high-value lipid production. However, mass-production of Amphora sp. NCC169 in traditional suspension photobioreactor is challenged by its sensitivity to stirring and turbulence. The aim of this study is to compare the biomass and lipid productivity of Amphora sp. NCC169 cultures between a Fernbach flask and a low-maintenance, laboratory-scale culture system adapted from previously described vertically oriented porous substrate bioreactor (PSBR) designs. Results revealed that cells in the PSBR could achieve significantly higher biomass productivity (Pbiomass = 0.51 ± 0.05 g·m−2·day−1) and lipid productivity (Plipid = 0.10 ± 0.03 g·m−2·day−1) than those in Fernbach flasks after 20 days of cultivation (Pbiomass = 0.29 ± 0.01 g m−2 day−1; Plipid = 0.07 ± 0.01 g·m−2·day−1). Cellular photosynthetic efficiency remained favorable in both culture conditions (Fv/Fm > 0.5) for the duration of the experiments.

Genome-Wide Analysis of Glycerol-3-Phosphate Acyltransferase (GPAT) Family in Perilla frutescens and Functional Characterization of PfGPAT9 Crucial for Biosynthesis of Storage Oils Rich in High-Value Lipids.

Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the first step in triacylglycerol (TAG) biosynthesis. However, GPAT members and their functions remain poorly understood in Perilla frutescens, a special edible-medicinal plant with its seed oil rich in polyunsaturated fatty acids (mostly α-linolenic acid, ALA). Here, 14 PfGPATs were identified from the P. frutescens genome and classified into three distinct groups according to their phylogenetic relationships. These 14 PfGPAT genes were distributed unevenly across 11 chromosomes. PfGPAT members within the same subfamily had highly conserved gene structures and four signature functional domains, despite considerable variations detected in these conserved motifs between groups. RNA-seq and RT-qPCR combined with dynamic analysis of oil and FA profiles during seed development indicated that PfGPAT9 may play a crucial role in the biosynthesis and accumulation of seed oil and PUFAs. Ex vivo enzymatic assay using the yeast expression system evidenced that PfGPAT9 had a strong GPAT enzyme activity crucial for TAG assembly and also a high substrate preference for oleic acid (OA, C18:1) and ALA (C18:3). Heterogeneous expression of PfGPAT9 significantly increased total oil and UFA (mostly C18:1 and C18:3) levels in both the seeds and leaves of the transgenic tobacco plants. Moreover, these transgenic tobacco lines exhibited no significant negative effect on other agronomic traits, including plant growth and seed germination rate, as well as other morphological and developmental properties. Collectively, our findings provide important insights into understanding PfGPAT functions, demonstrating that PfGPAT9 is the desirable target in metabolic engineering for increasing storage oil enriched with valuable FA profiles in oilseed crops.

Simultaneous production of high-value lipids in Schizochytrium sp. by synergism of chemical modulators.

The study focuses on the simultaneous improvement of biomass, lipid, and docosahexaenoic acid (DHA) productivities in a single reactor using modulator control strategies. The efficacy of three different biochemical modulators, sesamol (Ses), 6-benzylaminopurine (6-BAP), and ethylenediaminetetraacetic acid (EDTA), as potential stimulants in augmenting the biomass, lipid, and DHA production of Schizochytrium sp. MTCC 5890 was elucidated. After 48h of cultivation, among tested modulators, the individual supplementation of 6-BAP and Ses showed improvement in biomass, lipid, and DHA accumulation by 28.2%, 56.1%, and 87.2% and 21.7%, 47.9%, and 91%, respectively, over the non-supplemented group. In addition, the cooperative effect of selected concentrations, i.e., 10 mgL-1 6-BAP and 200 mgL-1 Ses, further increased the productivities of biomass of 13.5 gL-1d-1 ± 0.66, lipid of 7.4 gL-1d-1 ± 0.69, and DHA of 3.2 gL-1d-1 ± 1.09 representing 8%, 39%, and 69% increase over the individual addition of 6-BAP or Ses, respectively, in batch culture. Supplementation with 6-BAP + Ses at 12h of time point eventually increased the lipid yield to 15.6 ± 0.42 gL-1 from 7.88 ± 0.31 gL-1 (control) and DHA yield to 6.4 ± 0.11 gL-1 from 2.23 ± 0.09 gL-1 (control), respectively. Furthermore, the process was optimized in continuous culture supplemented with 6-BAP + Ses for enhanced productivities. Continuous culture resulted in maximum biomass (2.04 ± 1.12 gL-1day-1), lipid (1.0 ± 0.73 gL-1day-1), and DHA (0.386 ± 0.22 gL-1day-1) productivities, which were higher as compared with the batch and fed-batch processes by 26 ± 1.21%, 22 ± 1.01%, and 21 ± 0.98% and 24 ± 0.45%, 16 ± 0.38%, and 14 ± 0.12%, respectively. This work represents the potential application of the combined effect of modulators for the simultaneous enhancement of biomass production and lipid and DHA productivities. KEY POINTS: • The cumulative study of 6-BAP and sesamol proved to be more efficient in the simultaneous production of biomass, lipid, and DHA in a single reactor. • Addition of a combination of 6-BAP + Ses remarkably increased the biomass, lipid, and DHA productivities in tandem in continuous culture.

Deciphering the change pattern of lipid metabolism in Saccharomyces cerevisiae responding to low temperature

In fermentation, the yield of some lipid products is deeply affected by thermal variation. However, changes in lipid metabolism responding to low temperature are still poorly understood. In this work, transcriptome and lipidomic analysis were carried out to depict the changes of lipid metabolism at low and optimal temperature. Transcriptome analysis demonstrated that ribosome biogenesis and carbon metabolism were the most enrichment pathways induced by the dropped temperature. The data revealed that yeast cells adjusted membrane fluidity by altering the contents of different lipid species (phospholipids, glycerides, sphingolipids and sterols) apart from adjusting the unsaturation level of the corresponding fatty acids. According to the transcriptome analysis of glucose-energy metabolism, Snf1 was considered as the core regulator of energy metabolism in yeast’ adapting to low temperature. These findings improve our understanding of the carbon metabolism of Saccharomyces cerevisiae under cold stress and provide valuable information for the production of high-value lipid products through metabolic engineering.

Microalgal glycerol-3-phosphate acyltransferase role in galactolipids and high-value storage lipid biosynthesis.

Glycerolipids are the most abundant lipids in microalgae, and glycerol-3-phosphate:acyl-CoA acyltransferase (GPAT) plays an important role in their biosynthesis. However, the biochemical and biological functions of algal GPAT remain poorly characterized. Here, we characterized the endoplasmic reticulum (ER)-associated GPAT of the model unicellular green alga Chlamydomonas reinhardtii (CrGPATer). Enzymatic assays indicated that CrGPATer is an sn-1 acyltransferase using a variety of acyl-CoAs as the acyl donor. Subcellular localization revealed that CrGPATer was associated with ER membranes and lipid droplets. We constructed overexpression (OE) and knockdown (KD) transgenic C. reinhardtii lines to investigate the in vivo function of CrGPATer. Lipidomic analysis indicated that CrGPATer OE enhanced the cellular content of galactolipids, especially monogalactosyldiacylglycerol, under nitrogen deficiency stress. Correspondingly, CrGPATer KD lines contained lower contents of galactolipids than the control. Feeding experiments with labeled phosphatidic acid revealed that the intermediate of the eukaryotic Kennedy pathway could be used for galactolipid biosynthesis in the chloroplasts. These results provided multiple lines of evidence that the eukaryotic Kennedy pathway mediated by CrGPATer may be involved in galactolipid biosynthesis in C. reinhardtii. OE of CrGPATer significantly increased the content of triacylglycerol and the yield of biomass. Moreover, the content and yield of 1, 3-olein-2-palmitin, a high-value lipid that can be used as an alternative for human milk fat in infant formula, were significantly enhanced in the OE transgenic lines. Taken together, this study provided insights into the biochemical and biological functions of CrGPATer and its potential as a genetic engineering target in functional lipid manufacturing.

Expression of glycerol-3-phosphate acyltransferase increases non-polar lipid accumulation in Nannochloropsis oceanica

Microalgae are considered a suitable production platform for high-value lipids and oleochemicals. Several species including Nannochloropsis oceanica produce large amounts of essential omega-3 polyunsaturated fatty acids (PUFAs) which are integral components of food and feed and have been associated with health-promoting effects. N. oceanica can further accumulate high contents of non-polar lipids with chemical properties that render them a potential replacement for plant oils such as palm oil. However, biomass and lipid productivities obtained with microalgae need to be improved to reach commercial feasibility. Genetic engineering can improve biomass and lipid productivities, for instance by increasing carbon flux to lipids. Here, we report the overexpression of glycerol-3-phosphate acyltransferase (GPAT) in N. oceanica during favorable growth conditions as a strategy to increase non-polar lipid content. Transformants overproducing either an endogenous (NoGPAT) or a heterologous (Acutodesmus obliquus GPAT) GPAT enzyme targeted to the endoplasmic reticulum had up to 42% and 51% increased non-polar lipid contents, respectively, compared to the wild type. Biomass productivities of transformant strains were not substantially impaired, resulting in lipid productivities that were increased by up to 37% and 42% for NoGPAT and AoGPAT transformants, respectively. When exposed to nutrient stress, transformants and wild type had similar lipid contents, suggesting that GPAT enzyme exerts strong flux control on lipid synthesis in N. oceanica under favorable growth conditions. NoGPAT transformants further accumulated PUFAs in non-polar lipids, reaching a total of 6.8% PUFAs per biomass, an increase of 24% relative to the wild type. Overall, our results indicate that GPAT is an interesting target for engineering of lipid metabolism in microalgae, in order to improve non-polar lipid and PUFAs accumulation in microalgae.

Extraction of High-Value Lipids and Phenolic Compounds from Sorghum Bran via a Sequential Supercritical Carbon Dioxide Approach

Extraction of High-Value Lipids and Phenolic Compounds from Sorghum Bran via a Sequential Supercritical Carbon Dioxide Approach

Maximizing unsaturated fatty acids production by using sugarcane agroindustry wastes in cultivation of Desmodesmus sp. in a flat plate photobioreactor

Microalgae lipid accumulation can be accomplished by different strategies rather than naturally reaching the stationary phase. Many studies employ nitrogen (N) depletion to improve lipid production; however, this approach might not be a suitable alternative when growth in wastewater is attempted. Agro-industry effluents in particular can have high concentrations of N, so nutrient removal is also required. This study evaluated two possibilities of achieving stress conditions in Desmodesmus sp. cultivation: light intensity and CO2 concentration. The culture medium also included liquid and solid residues from the sugarcane agro-industry: vinasse and a biofertilizer produced from bagasse biochar. Optimization of growth in a flat plate photobioreactor was conducted by combining a two-level factorial design and simplex methodology. Both the highest biomass and polyunsaturated fatty acid productivities (150.2 and 21.4 mg L−1 day−1, respectively) were achieved near the central points (5% CO2 in air and 1000 μmol m−2 s−1 light intensity). These results show the possibility of microalgae growth in a sustainable medium coupled with high-value lipid production, e.g., omegas-3, − 6, and − 9.

Chrysotila pseudoroscoffensis as a source of high-value polar lipids with antioxidant activity: A lipidomic approach

Microalgae are emerging as sustainable sources of a wide range of high-value compounds. However, the knowledge about microalgae polar lipids is still limited, despite their interest due to their chemical diversity and bioactivity. This study shows, for the first time, the polar lipidome of the haptophyte microalga Chrysotila pseudoroscoffensis unveiled by using hydrophilic interaction liquid chromatography-high resolution mass spectrometry (HILIC-HRMS and MS/MS) and gas chromatography–mass spectrometry (GC–MS). Freeze-dried C. pseudoroscoffensis biomass has a lipid content of 6.4 %, containing higher amounts of ash (45.5 %), proteins (11.6 %), and sugars (11.0 %). Uronic acids (53.8 mol%) are the sugars present in higher content, followed by glucose (13.7 mol%) and galactose (12.7 mol%). The polar lipid species identified by HILIC-MS/MS included betaine lipids, glycolipids, and phospholipids, some of them with recognised bioactive properties. Among the lipid classes found from C. pseudoroscoffensis, some are less reported in algae: betaine lipids diacylglycerylcarboxyhydroxymethylcholine (DGCC) and monoacylglycerylcarboxyhydroxymethylcholine (MGCC) (characteristic of haptophyte microalgae); acid glycolipid class glucuronosyldiacylglycerol (GlcADG) (mainly reported in plants with protective effects in phosphate-deprivation conditions); and phospholipid classes monomethylphosphatidylethanolamine (MMPE) and lysomonomethylphosphatidylethanolamine (MMLPE). As estimated by colorimetric assays, glycolipids and phospholipids accounted for 64 and 3 % of the total lipid extracts, respectively. Fatty acid profiling by GC–MS showed that total esterified fatty acids accounted for about 32 % of the total lipid extracts, of which 23 % were omega-3 polyunsaturated fatty acids (PUFA). Four lipid extract concentrations (12.5, 62.5, 125 and 250 μg mL−1 in ethanol) were tested and displayed antioxidant capacity toward 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. A dose-dependent behaviour was observed with IC50 of 111.9 μg mL−1 for ABTS and IC35 of 234.8 μg mL−1 for DPPH assay. In conclusion, the lipid extracts of C. pseudoroscoffensis may be a source of high-value lipids for the development of novel microalgae-based products, namely nutraceuticals and cosmeceuticals.

Canvasing the Substrate-Binding Pockets of the Wax Ester Synthase.

The biosynthesis of wax esters and triglycerides in bacteria is accomplished through the action of the wax ester synthase/acyl-coenzyme A:diacylglycerol acyltransferase (WS/DGAT or wax ester synthase). A hallmark of these enzymes is the broad substrate profile that accepts alcohols, diglycerides, and fatty acyl-CoAs of various carbon chain lengths and degrees of branching. These enzymes have a broad biotechnological potential due to their role in producing high-value lipids or simple fuels similar to biodiesel through biosynthetic routes. Recently, a crystal structure was solved for the wax ester synthase from Marinobacter aquaeolei VT8 (Maqu_0168), providing a much clearer picture of the architecture of this enzyme and enabling a more precise analysis of the important structural features of the protein. In this work, we used the structure to canvas amino acids lining the proposed substrate-binding pockets and tested the effects of exchanging specific residues on the substrate profiles. We also developed an approach to better probe the residues that alter fatty acyl-CoA selectivity, which has proven more difficult to investigate. Our findings provide an improved blueprint for future efforts to understand how these enzymes position substrates for catalysis and to tailor or improve these enzymes in future biosynthetic schemes.

High-value lipids accumulation by Pavlova pinguis as a response to nitrogen-induced changes

The challenges of exploring the potential of microalgal strains for biotechnological applications include the optimization of their cell growth and chemical composition. To overcome this, it is essential to understand the mechanisms that lead to the accumulation of desired products within microalgal cells. In this study, a gradient of nitrogen as nitrate (NO3−−N) concentrations was used for the preparation of P. pinguis growth medium. The algal growth dynamics, pigments, nutrient uptake, and detailed lipid composition across treatments were assessed. Increasing the NO3−−N level led to higher lipid content (21%), a higher cell uptake rate (0.20 pg NO3−−N cell−1 d−1) and more accumulation of chlorophylls, carotenoids, and high-value lipids. Eicosapentaenoic acid, essential fatty acids, phytol and stigmasterol were the key high-value lipids that were positively influenced by higher NO3−−N levels. High NO3−−N conditions induced an increase of 54% in total sterol content, while low NO3−−N conditions resulted in increased proportions of saturated fatty acids (66% more) and decreased proportions of polyunsaturated fatty acids (14% less). The low NO3−−N level also led to higher amounts of monoglyceride (1.60 mg g−1; 64% more). The analysis of P. pinguis lipids before and after hydrolysis provided an insight into the composition of the esterified lipids across treatments. NO3−−N supplementation was revealed to be an effective strategy for enhancing P. pinguis lipid composition, for nutraceutical and pharmaceutical industries (high NO3−−N level). A greater understanding of the NO3−−N uptake and the use efficiency by P. pinguis was reached, showing its potential for further biotechnological applications.

Effects of phosphorus-induced changes on the growth, nitrogen uptake, and biochemical composition of Pavlova pinguis and Hemiselmis cf. andersenii

The understanding of the phosphorus-induced changes in the biochemical composition of microalgae is of great importance for achieving efficiency in high-value lipid production. To study the chemoplasticity of Pavlova pinguis (Haptophyceae) and Hemiselmis cf. andersenii (Cryptophyceae), their growth, carotenoid and chlorophyll a content, and their monosaccharide and lipid profiles were analyzed against several phosphorus (P) regimes: low (LP), medium (MP), and high (HP). For both microalgal cultures, increasing initial P concentrations showed a positive effect on biomass productivities. Carbon-rich pools presented significant differences (p< 0.05) for P. pinguis against P treatments, in contrast to H. cf. andersenii. Differential responses to P-induced changes in microalgae monosaccharide and lipid profile were observed. Hemiselmis cf. andersenii increased its proportion in galactose (up to 3 times) from LP to HP conditions, whereas P. pinguis decreased (up to 20%) its glucose proportion from LP to HP conditions. For P. pinguis, the lowest amount (13.12 mg g−1 dw) of sterols was observed at LP conditions, in contrast to its carotenoid content (4.32 mg g−1 dw). P-replete conditions were the most effective in inducing high-value lipid accumulation. Non-targeted lipid analysis revealed which samples would need to be processed to fully exploit its high-value lipids, namely H. cf andersenii under MP and HP conditions. This study demonstrated that P played an important role in carbon allocation, nitrogen uptake, and lipid regulation on P. pinguis and H. cf. andersenii, and that P-replete conditions could be useful for optimizing high-value lipids with potential for nutraceutical and pharmaceutical fields.

Aeroterrestrial and Extremophilic Microalgae as Promising Sources for Lipids and Lipid Nanoparticles in Dermal Cosmetics

Microscopic prokaryotic and eukaryotic algae (microalgae), which can be effectively grown in mass cultures, are gaining increasing interest in cosmetics. Up to now, the main attention was on aquatic algae, while species from aeroterrestrial and extreme environments remained underestimated. In these habitats, algae accumulate high amounts of some chemical substances or develop specific compounds, which cause them to thrive in inimical conditions. Among such biologically active molecules is a large family of lipids, which are significant constituents in living organisms and valuable ingredients in cosmetic formulations. Therefore, natural sources of lipids are increasingly in demand in the modern cosmetic industry and its innovative technologies. Among novelties in skin care products is the use of lipid nanoparticles as carriers of dermatologically active ingredients, which enhance their penetration and release in the skin strata. This review is an attempt to comprehensively cover the available literature on the high-value lipids from microalgae, which inhabit aeroterrestrial and extreme habitats (AEM). Data on different compounds of 87 species, subspecies and varieties from 53 genera (represented by more than 141 strains) from five phyla are provided and, despite some gaps in the current knowledge, demonstrate the promising potential of AEM as sources of valuable lipids for novel skin care products.

Profiling of Essential Mineral Content, Heavy Metals, and Bacterial Contaminants in Conventional and Organic Eggs Available in the Hypermarkets of the Eastern Province of Saudi Arabia

Eggs are commonly regarded as one of the best sources of various macro and micronutrients, in particular, high biological value (BV) proteins and both saturated and unsaturated fatty acids. Apart from proteins, eggs are excellent sources of various high health value lipid components, carotenoids, minerals, and both water and lipid-soluble vitamins. However, the nutrient-rich nature of this 'superfood' also makes them susceptible to microbial contamination from various sources, such as fecal matter, drinking water for layer chicken, and the surrounding environment. Moreover, drinking water and chicken feed are also sources of heavy metal contamination. The presence of both factors poses serious health concerns for consumers. The main aim of this research was to proximate heavy metals and bacterial contaminants in nine different brands of brown organic and conventional white eggs available in the hypermarkets of the Eastern Province of Saudi Arabia. An Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) was used to determine the concentration of metals with high sensitivity. Standard plate count was followed by enrichment of bacterial contaminants in a double-strength nutrient broth medium for microbiological assessment. The results indicated that Pb, Cd, Al, and As were present in high concentrations in all egg brands of both types (organic and conventional). The estimated daily intake (EDI) values for Ca, Fe, Mn, and Mg were within the range of WHO-recommended thresholds, and these essential minerals were present in adequate amounts in all egg brands. The two major groups predominating the microbial loads were the family Enterobacteriaceae and Pseudomonas sp. The presence of heavy metals, such as Al, As, Pb, and Cd, in nearly all the brands in amounts that exceeded the established ADI and EDI thresholds was considerably concerning. In particular, the elevated levels of Cd and Pb in group 1 and group 2A probable human carcinogens, respectively, demands that local regulatory authorities investigate the sources of heavy metal contamination and alleviate this considerable risk to human health. Furthermore, this study could be a benchmark for establishing food safety and hygiene standards for local egg production, storage, handling, and transport in Saudi Arabia.

Use of Waste Substrates for the Lipid Production by Yeasts of the Genus Metschnikowia-Screening Study.

Oleogenic yeasts are characterized by the ability to accumulate increased amounts of lipids under certain conditions. These microbial lipids differ in their fatty acid composition, which allows them to be widely used in the biotechnology industry. The interest of biotechnologists is closely linked to the rising prices of fossil fuels in recent years. Their negative environmental impact is caused by significantly increased demand for biodiesel. The composition of microbial lipids is very similar to vegetable oils, which provides great potential for use in the production of biodiesel. In addition, some oleogenic microorganisms are capable of producing lipids with a high proportion of unsaturated fatty acids. The presented paper’s main aim was to study the production of lipids and lipid substances by yeasts of the genus Metschnikowia, to cultivate crude waste animal fat to study its utilization by yeasts, and to apply the idea of circular economy in the biotechnology of Metschnikowia yeasts. The work focuses on the influence of various stress factors in the cultivation process, such as reduced temperature or nutritional stress through the use of various waste substrates, together with manipulating the ratio of carbon and nitrogen sources in the medium. Yeast production properties were monitored by several instrumental techniques, including gas chromatography and Raman spectroscopy. The amount of lipids and in particular the fatty acid composition varied depending on the strains studied and the culture conditions used. The ability of yeast to produce significant amounts of unsaturated fatty acids was also demonstrated in the work. The most suitable substrate for lipid production was a medium containing glycerol, where the amount of accumulated lipids in the yeast M. pulcherrima 1232 was up to 36%. In our work, the crude animal fat was used for the production of high-value lipids, which to the best of our knowledge is a new result. Moreover, quantitative screening of lipase enzyme activity cultivated on animal fat substrate on selected yeasts of the genus Metschnikowia was performed. We found that for the yeast utilizing glycerol, animal fat seems to be an excellent source of carbon. Therefore, the yeast conversion of crude processed animal fat to value-added products is a valuable process for the biotechnology and food industry.

Graphene coated magnetic nanoparticles facilitate the release of biofuels and oleochemicals from yeast cell factories

Engineering of microbial cells to produce high value chemicals is rapidly advancing. Yeast, bacteria and microalgae are being used to produce high value chemicals by utilizing widely available carbon sources. However, current extraction processes of many high value products from these cells are time- and labor-consuming and require toxic chemicals. This makes the extraction processes detrimental to the environment and not economically feasible. Hence, there is a demand for the development of simple, effective, and environmentally friendly method for the extraction of high value chemicals from these cell factories. Herein, we hypothesized that atomically thin edges of graphene having ability to interact with hydrophobic materials, could be used to extract high value lipids from cell factories. To achieve this, array of axially oriented graphene was deposited on iron nanoparticles. These coated nanoparticles were used to facilitate the release of intracellular lipids from Yarrowia lipolytica cells. Our treatment process can be integrated with the growth procedure and achieved the release of 50% of total cellular lipids from Y. lipolytica cells. Based on this result, we propose that nanoparticles coated with axially oriented graphene could pave efficient, environmentally friendly, and cost-effective way to release intracellular lipids from yeast cell factories.

Microalgae as Sustainable Biofactories to Produce High-Value Lipids: Biodiversity, Exploitation, and Biotechnological Applications.

Microalgae are often called “sustainable biofactories” due to their dual potential to mitigate atmospheric carbon dioxide and produce a great diversity of high-value compounds. Nevertheless, the successful exploitation of microalgae as biofactories for industrial scale is dependent on choosing the right microalga and optimum growth conditions. Due to the rich biodiversity of microalgae, a screening pipeline should be developed to perform microalgal strain selection exploring their growth, robustness, and metabolite production. Current prospects in microalgal biotechnology are turning their focus to high-value lipids for pharmaceutic, nutraceutic, and cosmetic products. Within microalgal lipid fraction, polyunsaturated fatty acids and carotenoids are broadly recognized for their vital functions in human organisms. Microalgal-derived phytosterols are still an underexploited lipid resource despite presenting promising biological activities, including neuroprotective, anti-inflammatory, anti-cancer, neuromodulatory, immunomodulatory, and apoptosis inductive effects. To modulate microalgal biochemical composition, according to the intended field of application, it is important to know the contribution of each cultivation factor, or their combined effects, for the wanted product accumulation. Microalgae have a vital role to play in future low-carbon economy. Since microalgal biodiesel is still costly, it is desirable to explore the potential of oleaginous species for its high-value lipids which present great global market prospects.

Optimized production and enrichment of α-linolenic acid by Scenedesmus sp. HSJ296

The essential fatty acid α-linolenic acid is vital for human physiology and health. The green alga Scenedesmus sp. HSJ296 can accumulate large amounts of α-linolenic acid. In this work, we optimized the fermentation of Scenedesmus sp. HSJ296 in a 50-L fermenter, resulting in a biomass productivity of 3.12 ± 0.45 g L−1 d−1. We then extracted lipids from the biomass by supercritical fluid CO2 extraction with 95% ethanol as entrainer, achieving a lipid extraction rate as high as 73.47 ± 4.28%. After decolorization and enrichment by lipase hydrolysis, and low-temperature solvent crystallization, the content of unsaturated fatty acids in the lipid fraction from the biomass was enriched up to 92.5 ± 1.2%, with α-linolenic acid accounting for 62.6 ± 0.9%. The saturated fatty acids mainly consist of palmitic acid (C16:0, 3.1 ± 0.1%) and stearic acid (C18:0, 0.9 ± 0.1%). The remaining saturated fatty acid fraction, with relatively higher saturated fatty acid content, can be used as raw material for biodiesel production. Overall, we established an optimized α-linolenic acid production process that provides an important theoretical and technical basis for microalgae-based production of high-value lipids.