Production Of Polyunsaturated Fatty Acids Research Articles

Lipase Production by Yarrowia lipolytica in Solid-State Fermentation Using Amazon Fruit By-Products and Soybean Meal as Substrate

The production of polyunsaturated fatty acids from fish oil, which is related to various health benefits including effects against cardiovascular diseases, antihypertensive, anticancer, antioxidant, antidepression, anti-aging, and anti-arthritis effects, among others, can be advantageously performed through the application of lipase. However, the high cost associated with enzyme production can make the process unfeasible and thus alternative substrates should be investigated to solve these problems. This research aimed to produce lipase by Yarrowia lipolytica IMUFRJ50682 in solid-state fermentation using by-products of the food processing industry (andiroba oil cake and soybean meal) and verify the potential application in the initial hydrolysis of fish oil to further produce polyunsaturated fatty acids in a suitable process. A screening was carried out for the analysis of andiroba oil cake and soybean meal combinations in different proportions (0:100 to 100:0, respectively) at 48 h of the fermentation process. Afterward, the solid matrix composed by soybean meal and andiroba oil cake was supplemented with soy oil and Tween 80 to improve the lipase activity. The enzymatic extract was characterized in relation to the protein profile by electrophoresis. Finally, the enzymatic extract and the solid biocatalyst produced were applied to evaluate the potential hydrolysis of the fish oil in an initial study. Maximum lipolytic activity (63.7 U·g−1) was achieved using andiroba oil cake and soybean meal (50:50) after 24 h of fermentation. Soybean oil 1.5% and Tween 80 (0.001%) in an emulsion provided an increase of 1.5-fold (82.52 U·g−1) in the enzyme activity. The electrophoretic analysis demonstrated a band between 37 and 40 kDa that may be related to lipase and a band of 75 kDa referring to the α subunit of the β-conglycinin present in soybean meal. After 48 h, the solid biocatalyst showed a higher degree of hydrolysis (DH) (71.0%) than the enzymatic extract (61.5%). The solid biocatalyst was stable during storage at room temperature for 7 months. The production of lipases using Amazon fruit by-product and soybean meal in solid-state fermentation is viable as well as the application of the extract and solid biocatalyst in the initial application for the hydrolysis of fish oil to further produce polyunsaturated fatty acids in an industrially suited process.

Microalgae as Raw Materials for Aquafeeds: Growth Kinetics and Improvement Strategies of Polyunsaturated Fatty Acids Production.

Studies have shown that ancient cultures used microalgae as food for centuries. Currently, scientific reports highlight the value of nutritional composition of microalgae and their ability to accumulate polyunsaturated fatty acids at certain operational conditions. These characteristics are gaining increasing interest for the aquaculture industry which is searching for cost-effective replacements for fish meal and oil because these commodities are one of the most significant operational expenses and their dependency has become a bottleneck for their sustainable development of the aquaculture industry. This review is aimed at highlighting the use of microalgae as polyunsaturated fatty acid source in aquaculture feed formulations, despite their scarce production at industrial scale. Moreover, this document includes several approaches to improve microalgae production and to increase the content of polyunsaturated fatty acids with emphasis in the accumulation of DHA, EPA, and ARA. Furthermore, the document compiles several studies which prove microalgae-based aquafeeds for marine and freshwater species. Finally, the study explores the aspects that intervene in production kinetics and improvement strategies with possibilities for upscaling and facing main challenges of using microalgae in the commercial production of aquafeeds.

Okara Waste as a Substrate for the Microalgae Phaeodactylum tricornutum Enhances the Production of Algal Biomass, Fucoxanthin, and Polyunsaturated Fatty Acids

Despite the rich nutritional content of okara, the majority remains underutilized and discarded as food waste. In this study, solid-state fermentation of okara with food-grade fungi was performed to extract and solubilize any remnant nutrients locked within the lignocellulosic matrix to produce a nutrient-rich okara fermentate. Fermented okara media (FOM) was used as the sole nutrient source for growing marine diatom, Phaeodactylum tricornutum. Results have shown a two-fold increase in biomass production when grown on FOM (0.52 g L−1) as compared with conventional Guillard’s F/2 media (0.25 g L−1). Furthermore, cellular fucoxanthin content was enhanced significantly by two-fold to reach a final concentration of 15.3 mg g−1 compared to 7.3 mg g−1. Additionally, a significantly higher amount of polyunsaturated fatty acid (PUFA) was produced, particularly eicosapentaenoic acid (EPA) which yield has increased by nearly three-fold. Metabolomics analysis of intracellular contents in fermented okara culture revealed a significantly enhanced accumulation of nitrogenous metabolites, alongside the decrease in sugar metabolites as compared to F/2 culture, thus indicating metabolic flux towards pathways involved in cellular growth. This study demonstrated an innovative and low-cost strategy of using fermented okara as a nutritious substrate for achieving a sustainable media replacement for high density algal growth with a simultaneous enhancement of production in highly valued nutraceuticals, including fucoxanthin and EPA.

Agriculture of microalgae Chlorella vulgaris for polyunsaturated fatty acids (PUFAs) production employing palm oil mill effluents (POME) for future food, wastewater, and energy nexus

Malaysia is one of the second largest world palm oil exporters; correspondingly, the massive production of palm oil mill effluent (POME) is a significant concern. The present investigation aimed to isolate and characterize the potential microalgae and maximize the growth and biomass productivity of Chlorella sp. using POME. Chlorella vulgaris was cultured in BG-11 (control) and POME with 1:1, 1:2, 1:3, and 1:4 dilution ratios. Binary solvent extraction was applied to extract lipids, and polyunsaturated fatty acids (PUFAs) in the fatty acid methyl ethers were determined using gas chromatography coupled with mass spectrometry (GC-MS). Results suggest the lipid level of 21 wt.% was the highest amount obtained from biomass Chlorella vulgaris cultivated in 1:4 diluted POME. Chlorella sp. in POME with a 1:4 dilution ratio gives the highest biomass yield. It also yields the maximum dry cell weight of 0.42 g/L. Therefore, this study indicates that diluted POME with different dilutions is a suitable growth medium for Chlorella vulgaris biomass cultivation. Pairing wastewater with algae culture reduces biomass production and water treatment costs. Further studies demand more attention for future food, wastewater, and energy nexus.

Enhanced production of high-value polyunsaturated fatty acids (PUFAs) from potential thraustochytrid Aurantiochytrium sp.

Due to growing health concerns, the urban population is utterly inclined towards a healthy lifestyle and incorporated nutritional food supplements to lower common health risks. The ω-3 and ω-6 PUFAs consumption is increasing, hence alternative commercial production is essentially developed. The microbial source is an emerging platform to overcome the global demand for omega PUFAs. Marine oleaginous protist Aurantiochytrium sp. found a potential source to produce substantial DHA and SFA. The objective of the present research was to enhance the PUFA yield by optimizing maximum tolerable glucose concentration with a suitable nitrogen ratio (10:1). The maximum lipid and DHA yield and content were determined 4.30, 1.34 g/L, and 62.4, 33.49 % of total biomass and lipid at 30 g/L glucose respectively, which is one of among highest reported, however relative PUFA was maximum 46.97 % (DHA) in total lipid at 10 g/L glucose. Remaining 42–53.6 % SFA could be used for biodiesel.

Extracellular SQSTM1 exacerbates acute pancreatitis by activating autophagy-dependent ferroptosis

Acute pancreatitis (AP) is an abdominal inflammatory disease initiated by damaged pancreatic acinar cells and developed by systemic inflammation. SQSTM1 (sequestosome 1) has an intracellular function in mediating substrate degradation during macroautophagy/autophagy, and it can be released by macrophages and monocytes to trigger lethal inflammation during bacterial infection. Here, we report that extracellular SQSTM1 acts as a mediator of AP by enhancing the sensitivity to autophagy-dependent ferroptotic cell death. Serum SQSTM1 is elevated in AP patients as well as in mice that have cerulein-induced AP. The administration of SQSTM1-neutralizing antibodies protects against experimental AP in mice. Mechanistically, recombinant SQSTM1 protein (rSQSTM1) increases AGER (advanced glycosylation end-product specific receptor)-dependent ACSL4 (acyl-CoA synthetase long chain family member 4) expression, leading to polyunsaturated fatty acid production for autophagosome formation and subsequent ferroptosis. The rSQSTM1-elicited pathological responses during AP are attenuated in mice with the conditional deletion of Ager in the pancreas. These findings may provide not only new insights into the mechanism of autophagy-dependent cell death, but also suggest that targeting the extracellular SQSTM1 pathway is a potential strategy for the treatment of AP.

Plasma Levels of Omega-3 and Omega-6 Derived Oxylipins Are Associated with Fecal Microbiota Composition in Young Adults

Pre-clinical studies suggest that circulating oxylipins, i.e., the oxidation products of polyunsaturated fatty acids (PUFAs), modulate gut microbiota composition in mice, but there is no information available in humans. Therefore, this study aimed to investigate the relationship between omega-3 and omega-6 derived oxylipins plasma levels and fecal microbiota composition in a cohort of young adults. 80 young adults (74% women; 21.9 ± 2.2 years old) were included in this cross-sectional study. Plasma levels of oxylipins were measured using liquid chromatography-tandem mass spectrometry. Fecal microbiota composition was analyzed by V3-V4 16S rRNA gene sequencing. We observed that plasma levels of omega-3 derived oxylipins were positively associated with the relative abundance of Clostridium cluster IV genus (Firmicutes phylum; rho ≥ 0.415, p ≤ 0.009) and negatively associated with the relative abundance of Sutterella genus (Proteobacteria phylum; rho ≥ -0.270, p ≤ 0.041), respectively. Moreover, plasma levels of omega-6 derived oxylipins were negatively associated with the relative abundance of Acidaminococcus and Phascolarctobacterium genera (Firmicutes phylum; all rho ≥ -0.263, p ≤ 0.024), as well as Sutterella, Succinivibrio, and Gemmiger genera (Proteobacteria phylum; all rho ≥ -0.263, p ≤ 0.024). Lastly, the ratio between omega-6 and omega-3 oxylipins plasma levels was negatively associated with the relative abundance of Clostridium cluster IV genus (Firmicutes phylum; rho = -0.334, p = 0.004) and Butyricimonas genus (Bacteroidetes phylum; rho = -0.292, p = 0.014). In conclusion, our results show that the plasma levels of omega-3 and omega-6 derived oxylipins are associated with the relative abundance of specific fecal bacteria genera.

Novel Interactions of Myristic Acid and FADS3 Variants Predict Atopic Dermatitis among Indonesian Infants.

Fatty acids exert a range of different biological activities that could be relevant in the development of atopic dermatitis (AD). This study investigated the association of glycerophospholipid fatty acids (GPL-FA) with AD, and their interactions with single nucleotide polymorphisms (SNP) of the FADS1-3 gene cluster. Among 390 infants of the Indonesian ISADI study, GPL-FA were measured in umbilical plasma (P-0y) and in buccal cells at birth (B-0y), and again in buccal cells at AD onset or one year (B-1y). Prospective and cross-sectional associations with AD were assessed by logistic regression. Interactions of GPL-FA with 14 SNP were tested assuming an additive model. AD was diagnosed in 15.4% of participants. In B-1y, C18:2n-6 was inversely associated with AD; and positive associations were observed for C18:1n-9, C20:4n-6, C22:6n-3 and C20:4n-6/C18:2n-6. There were no prospective associations with AD, however, a significant interaction between the SNP rs174449 and B-0y C14:0 (myristic acid) was observed. This study indicates that Indonesian infants with AD have increased rates of endogenous long-chain polyunsaturated fatty acid production, as well as higher C18:1n-9 levels. GPL-FA measured at birth do not predict later AD incidence; however, genotype interactions reveal novel effects of myristic acid, which are modified by a FADS3 variant.

Contribution of anthocyanin and polyunsaturated fatty acid biosynthesis to cold tolerance during bud sprouting in tree peony

Tree peony is an economically important crop that is widely used in the food, floriculture, and pharmaceutical industries. However, the buds of tree peony are susceptible to low temperature stress. To elaborate the metabolic and transcriptional changes during bud sprouting, we performed metabolite and transcriptome analyses of the buds of Paeonia suffruticosa cultivar ‘Yulouchun’ at three developmental stages under low temperature treatment. The results showed that the contents of anthocyanin and α-linolenic acid (ALA) increased, concomitant with increased production of sucrose, gibberellic acid, indolylacetic acid, trans -zeatin riboside, and jasmonic acid as well as reduced accumulation of abscisic acid. Transcriptome profiling revealed 6355 differentially expressed genes (DEGs) during bud growth. We identified many structural DEGs whose expression was correlated with the accumulation of anthocyanin, ALA, sucrose, and hormones. In particular, the expression of transcription factors (TFs) PsMYB113 and PsMYB123 was found to be positively correlated with anthocyanin biosynthetic genes flavonoid 3′,5′-Hydroxylase , dihydroflavonol 4-reductase ( DFR ), anthocyanidin synthase ( ANS ), and two UDP-glycosylatransferase s. A positive correlation between a bZIP TF PsDPBF3 and an ALA biosynthetic gene fatty acid desaturase3 ( FAD3 ) was also found. Transcript abundances of these TFs and structural genes changed under sucrose and hormone treatments. Silencing of PsMYB113 and PsMYB123 resulted in decreased anthocyanin production and tolerance to freezing in tree peony buds. In addition, PsDPBF3 -silenced buds displayed reduced ALA levels and low temperature hardiness. In vivo promoter-binding assays verified that both PsMYB113 and PsMYB123 trans-activated the expression of DFR and ANS , while PsDPBF3 specifically regulated the transcription of FAD3 . Taken together, our data suggest that the production of anthocyanin and polyunsaturated fatty acid is closely implicated in cold tolerance of tree peony buds. • Cold stress increased various metabolite contents during bud sprouting of tree peony. • Transcriptome profiling revealed 6355 DEGs in cold-treated tree peony buds. • Silencing of PsMYB113 , PsMYB123 , and PsDPBF3 led to reduced tolerance to cold stress. • PsMYB113 and PsMYB123 bound to the promoters of anthocyanin-related DFR and ANS. • PsDPBF3 specifically trans-activated the expression of PUFA-associated FAD3 .

Integration of the Exogenous Tuning of Thraustochytrid Fermentation and Sulfur Polymerization of Single-Cell Oil for Developing Plant-like Oils.

In this study, we have demonstrated a bioprocessing approach encompassing the exogenous addition of low-molecular-weight compounds to tune the fatty acid (FA) profile in a novel thraustochytrid strain to produce desirable FAs. Maximum lipid recovery (38%, dry wt. biomass) was obtained at 1% Tween 80 and 0.25 mg/L of Vitamin B12. The transesterified lipid showed palmitic acid (C16, 35.7% TFA), stearic acid (C18, 2.1% TFA), and oleic acid (C18:1, 18.7% TFA) as the main components of total FAs, which are mainly present in plant oils. Strikingly, D-limonene addition in the fermentation medium repressed the production of polyunsaturated fatty acid (PUFAs). Sulfur-polymerization-guided lipid separation revealed the presence of saturated (SFAs, 53% TFA) and monounsaturated fatty acids (MUFAs, 46.6% TFA) in thraustochytrid oil that mimics plant-oil-like FA profiles. This work is industrially valuable and advocates the use of sulfur polymerization for preparation of plant-like oils through tuneable thraustochytrid lipids.

Comparative transcriptomic and lipidomic analyses indicate that cold stress enhanced the production of the long C18-C22 polyunsaturated fatty acids in Aurantiochytrium sp.

Aurantiochytrium sp. belonging to Thraustochytrids are known for their capacity to produce long-chain polyunsaturated fatty acids (PUFAs). However, effects of cold stress accompanied with staged-temperature control on the fatty acid metabolism in Aurantiochytrium sp. were rarely studied. In this study, cold stress (15°C, 5°C) was applied for Aurantiochytrium sp., with the physiological responses (morphology, growth, fatty acid profiling) and gene expression related FA synthesis, lipid metabolism, and regulatory processes was observed. Results showed that there is a significant change for the lipid types under 5°C (251 species) and 15°C (97 species) treatment. The 5°C treatment was benefit for the C18–C22 PUFAs with the yield of docosahexaenoic acid (DHA) increased to 1.25 times. After incubation at 15°C, the accumulation of eicosadienoic acid (EA) (20:2) was increased to 2.00-fold. Based on transcriptomic and qPCR analysis, an increase in genes involved in fatty acid synthase (FAS) and polyketide synthase (PKS) pathways was observed under low-temperature treatment. With upregulation of 3-ketoacyl-CoA synthase (2.44-fold), ketoreductase (2.50-fold), and dTDP-glucose 4,6-Dehydratase (rfbB) (2.31-fold) involved in PKS pathway, the accumulation of DHA was enhanced under 5°C. While, FAS and fatty elongase 3 (ELO) involved in the FAS pathway were upregulated (1.55-fold and 2.45-fold, respectively) to accumulate PUFAs at 15°C. Additionally, glycerol-3-phosphate acyltransferase (GPAT), lysophospholipid acyltransferase (LPAT), phosphatidic acid phosphatase (PAP), phosphatidylserine synthase (PSS), and phosphatidylserine decarboxylase (PSD) involved in glycerophospholipid biosynthesis were upregulated at 5°C increasing the accumulation of phosphatidic acid (PA), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and phosphatidylinositol (PI). However, glycolysis and the TCA cycle were inhibited under 5°C. This study provides a contribution to the application of two-staged temperature control in the Aurantiochytrium sp. fermentation for producing cold stress-enhancing PUFAs, in order to better understand the function of the key genes for future genetic engineering.

Can sensory boar taint levels be explained by fatty acid composition and emitted volatile organic compounds in addition to androstenone and skatole content?

This study aimed at understanding which molecules were responsible for the differences existing in boar taint sensory evaluation. The latter was therefore linked to the results of skatole and androstenone chemical analyses, fatty acid composition and VOC profiles of heated backfat. This study confirmed that some discrepancy exists between chemical analysis and sensory evaluation of tainted backfats. Significant correlations between human nose scores and fatty acid composition were not revealed. Strong correlations between emissions and contents in skatole and androstenone were found. Oxidation products of polyunsaturated fatty acids, with fatty odor descriptors, were found to be more present in the VOC profiles of boar fat considered untainted through the human nose methodology. Weak coefficient of determination for partial least square regression indicates that other factors, yet unknown, are responsible for sensory evaluation outcomes. These findings hence support the idea that high human nose score is mainly due to boar taint compounds rather than general differences in VOC profiles.

Silencing 1,3-β-glucan synthase gene promotes total lipid production and changes fatty acids composition by affecting carbon flow distribution in Phaeodactylum tricornutum

To clarify the effect of 1,3-β-glucan (known as chrysolaminarin) synthase ( Pt BGS) on carbon flow distribution, expression of 1,3-β-glucan synthase gene ( Ptbgs ) was silenced by RNA interference in Phaeodactylum tricornutum . The results showed that the chrysolaminarin content in all transgenic strains was significantly lower than that in the wild-type (WT), while the total lipid content increased to varying degrees. Importantly, the decrease in chrysolaminarin content was significantly correlated with the increase in total lipid content. There was no significant difference in the protein content between all the transgenic strains and WT. Thus, Pt BGS mainly affected the distribution of carbon flow in total lipids and polysaccharides , mainly chrysolaminarin. Silencing Ptbgs changed the fatty acids composition , and specifically promoted polyunsaturated fatty acids production and reduced monounsaturated fatty acids content, but had only a little effect on saturated fatty acids content. Interestingly, the growth of transgenic strains was not influenced while the lipid content increased, indicating that Ptbgs silencing may be an effective strategy to improve lipid production in diatoms. • Distribution of carbon flow can be affected by 1,3-β-glucan synthase ( Pt BGS). • Inhibiting the expression of Ptbgs promoted lipid accumulation. • Silencing Ptbgs changed the fatty acids composition. • Interfering with Ptbgs exerted little effect on growth in Phaeodactylum tricornutum . • Ptbgs silencing may be an effective strategy to improve lipid production in diatoms.

Whole genome analysis and elucidation of docosahexaenoic acid (DHA) biosynthetic pathway in Aurantiochytrium sp. SW1

Aurantiochytrium sp., a fungoid marine protist that belongs to Stramenophila has proven its potential in the production of polyunsaturated fatty acids (PUFAs), especially docosahexaenoic acids (DHA). In this study, genomic characterisation of a potential producer for commercial production of DHA, Aurantiochytrium sp. SW1 has been carried out via whole genome sequencing analysis. The genome size of this strain is 60.89 Mb, with a total of 11,588 protein-coding genes. Among these, 9,127 genes could be functionally annotated into a total of 7,248 (62.5 %) from UniProt, 6,554 (56.6 %) from KEGG and 8,643 (74.6 %) genes from eggNOG protein database. The highest proportion of genes belongs to the protein family of metabolism were further assigned into 11 metabolic categories. The highest number of genes belonging to lipid metabolism (321 genes) followed by carbohydrate metabolism (290 genes), metabolism of cofactors and vitamins (197 genes) and amino acid metabolism (188 genes). Further analysis into the biosynthetic pathway for DHA showed evidence of all genes involved in PKS (polyketide synthase)-like PUFA synthase pathway and incomplete fatty acid synthase-elongase/desaturase pathway. Analysis of PUFA synthase showed the presence of up to ten tandem acyl carrier protein (ACP) domains which might have contributed to high DHA production in this organism. In addition, a hybrid system incorporating elements of FAS, Type I PKS and Type II PKS systems were found to be involved in the biosynthetic pathways of fatty acids in Aurantiochytrium sp. SW1. This study delivers an important reference for future research to enhance the lipid, especially DHA production in Aurantiochytrium sp, SW1 and establishment of this strain as an oleaginous thraustochytrid model.

Homologous and Heterologous Expression of Delta(12)-Desaturase in Mucor circinelloides Enhanced the Production of Linolenic Acid.

Linolenic acid (LA) is gaining more interest within the scientific community. This is because it has a potential medical role in reducing the risk of inflammation, carcinogenesis, atherosclerosis and diabetes and is a valuable nutraceutical for human health. The oleaginous fungus Mucor circinelloides produces a high lipid content (36%), including valuable polyunsaturated fatty acids (PUFAs). However, the critical step in which oleic acid (OA) is converted into LA is not efficient at supplying enough substrates for PUFA synthesis. Hence, we propose a method to increase LA production based on genetic engineering. The overexpression of the Δ12-desaturase gene from M. circinelloides and Mortierella alpina increased the LA content and improved the lipid accumulation (from 14.9% to 21.6% in the Δ12-desaturase gene of the M. circinelloides overexpressing strain (Mc-D12MC) and from 14.9% to 18.7% in the Δ12-desaturase gene of M. alpina overexpressing strain (Mc-D12MA)). Additionally, the up-regulated expression levels of these genes targeted the genes involved in NADPH production, implying that the elevated Δ12-desaturase gene may function as a critical regulator of NADPH and lipid synthesis in M. circinelloides. This study provides the first evidence to support the design of metabolic engineering related to LA and PUFA production in M. circinelloides for potential industrial applications.

Utilization of saline and viscous food-processing liquid waste for cultivation of thraustochytrid for production of polyunsaturated fatty acids

Utilization of saline and viscous food-processing liquid waste for cultivation of thraustochytrid for production of polyunsaturated fatty acids

Combined effects of eutrophication and warming on polyunsaturated fatty acids in complex phytoplankton communities: A mesocosm experiment

Climate change and eutrophication are among the main stressors of shallow freshwater ecosystems, and their effects on phytoplankton community structure and primary production have been studied extensively. However, their combined effects on the algal production of polyunsaturated fatty acids (PUFA), specifically, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are currently unresolved. Moreover, the proximate reasons for changes in phytoplankton EPA and DHA concentrations are unclear, i.e., the relative importance of ecological (changes in the community composition) vs. ecophysiological (within taxa changes in EPA and DHA levels) factors.We investigated the responses of phytoplankton EPA and DHA concentrations to warming (IPCC climate scenario) and nutrient additions in mesocosms which had been run continuously at varying temperature and nutrient levels for 15 years prior to this study. Nutrient treatment had a significant effect on phytoplankton EPA and DHA concentrations and about 59 % of the variation in EPA and DHA concentrations could be explained by changes in the phytoplankton community structure. Increased biomass of diatoms corresponded with high EPA and DHA concentrations, while cyanobacteria/chlorophyte dominated mesocosm had low EPA and DHA concentrations. Warming had only a marginal effect on the EPA and DHA concentrations in these mesocosms. However, a significant interaction was observed with warming and N:P ratio.Our findings indicate that direct nutrient/temperature effects on algal physiology and PUFA metabolism were negligible and the changes in EPA and DHA concentrations were mostly related to the phytoplankton community structure and biomass. These results also imply that in shallow temperate lakes eutrophication, leading to increased dominance of cyanobacteria, will probably be a greater threat to phytoplankton EPA and DHA production than warming. EPA and DHA are nutritionally important for upper trophic level consumers and decreased production may impair secondary production.

Dark stress for improved lipid quantity and quality in bioprospected acid-tolerant green microalgae.

The cost of microalgae cultivation is one of the largest limitations to achieving sustainable, large-scale microalgae production of commercially desirable lipids. Utilizing CO2 as a 'free' carbon source from waste industrial flue gas emissions can offer wide-ranging cost savings. However, these gas streams typically create acidic environments, in which most microalgae cannot survive due to the concentration of CO2 and the presence of other acidic gasses such as NO2 and SO2. To address this situation, we investigated growth of a mixed acid-tolerant green microalgal culture (91% dominated by a single Coccomyxa sp. taxon) bioprospected at pH 2.8 from an acid mine drainage impacted water body. The culture was grown at pH 2.5 and fed with a simulated flue gas containing 6% CO2 and 94% N2. On reaching the end of the exponential growth phase, the culture was exposed to either continued light-dark cycle conditions or continual dark conditions. After three days in the dark, the biomass consisted of 28% of lipids, which was 42% higher than at the end of the exponential phase and 55% higher than the maximum lipid content achieved under light/dark conditions. The stress caused by being continually in the dark also favoured the production of omega-3 and omega-6 polyunsaturated fatty acids (PUFAs; 19.47% and 21.04%, respectively, after 7 days) compared to 7-days of light-dark treatment (1.94% and 9.53%, respectively) and showed an increase in nitrogen content (C:N ratio of 6.4) compared to light-dark treatment (C:N ratio of 11.9). The results of the research indicate that use of acid tolerant microalgae overcomes issues using flue gasses that will create an acidic environment and that applying dark stress is a low-cost stressor stimulates production of desirable dietary lipids.

Microalgae-Based PUFAs for Food and Feed: Current Applications, Future Possibilities, and Constraints

Microalgae are currently considered an attractive source of highly valuable compounds for human and animal consumption, including polyunsaturated fatty acids (PUFAs). Several microalgae-derived compounds, such as ω-3 fatty acids, pigments, and whole dried biomasses are available on the market and are mainly produced by culturing microalgae in open ponds, which can be achieved with low setup and maintenance costs with respect to enclosed systems. However, open tanks are more susceptible to bacterial and other environmental contamination, do not guarantee a high reproducibility of algal biochemical profiles and productivities, and constrain massive cultivation to a limited number of species. Genetic engineering techniques have substantially improved over the last decade, and several model microalgae have been successfully modified to promote the accumulation of specific value-added compounds. However, transgenic strains should be cultured in closed photobioreactors (PBRs) to minimize risks of contamination of aquatic environments with allochthonous species; in addition, faster growth rates and higher yields of compounds of interest can be achieved in PBRs compared to open ponds. In this review, we present information collected about the major microalgae-derived commodities (with a special focus on PUFAs) produced at industrial scale, as well genetically-engineered microalgae to increase PUFA production. We also critically analyzed the main bottlenecks that make large-scale production of algal commodities difficult, as well as possible solutions to overcome the main problems and render the processes economically and environmentally safe.

Eco-friendly production of nutraceutical and cosmeceutical fatty acids by oleaginous fungus Lichtheimia hyalospora UCP 1266 using renewable substrates

Polyunsaturated fatty acids (PUFAs) are essential for human functions and can be used in nutraceuticals; however, traditional sources are environmentally unsustainable. A promising strategy to reduce the production costs of PUFAs is the use of economical agro-industrial sources as substrates in culture media for oleaginous microorganisms. In this study, we investigated the potential of the fungus Lichtheimia hyalospora UCP 1266 (isolated from the Caatinga soil, Brazil) in the production of PUFAs, through the metabolic conversion of alternative substrates crude glycerol (CG) and corn steep liquor (CSL). The cultivation of L. hyalospora UCP 1266 in medium containing glucose (Synthetic Medium for Mucorales - SMM) yielded 2.1 g/L of biomass and 0.6 g/L of total lipids. However, assay 4 of the 22 full-factorial design, with CG 8% and CSL 8%, provided higher yields of biomass (15.5 g/L) and total lipids (12.8 g/L). The lipids produced in this medium presented a composition of saturated, monounsaturated and polyunsaturated fatty acids (SFAs=35.13%, MUFAs=46.09% and PUFAs=18.14%). The microorganism proved to be promising in the production of omega 6 (linoleic acid, C18:2), γ-linolenic acid (C18:3), omega 3 (α-linolenic acid, C18:3) and omega 9 (oleic acid, C18:1). The results indicated L. hyalospora UCP 1266 as an oleaginous fungus with great potential for use in the development of nutraceutical ingredients for food or applied in cosmeceuticals and/or nutricosmetics.