Optimization of docosahexaenoic acid production by Schizochytrium limacinum SR21

Culture conditions of Schizochytrium limacinum SR21 for the purpose of microbial docosahexaenoic acid (DHA) production were investigated. The strain SR21 showed a wide tolerance to salinity; that is, the optimum salinity was between 50% and 200% that of sea water. Monosaccharides (glucose and fructose) and glycerol supported good cell growth and DHA yield. Di- and polysaccharides, oleic acid, and linseed oil gave low DHA yields. A high content of DHA (more than 30% of total fatty acids) was obtained from culture on glucose, fructose, and glycerol, and also the strain had simple polyunsaturated fatty acid profiles. The major polyunsaturated fatty acids other than DHA were n-6 docosapentaenoic acid only, and the contents of icosapentaenoic acid and arachidonic acid were less than 1%. Using corn steep liquor as a nitrogen source, a high total fatty acid content was obtained. The total fatty acid content in the dry cell weight increased as the concentration of the nitrogen source decreased, reached more than 50%. An increase in carbon source concentration led to a high DHA yield. A maximum DHA yield of more than 4 g/l was obtained in both glucose and glycerol media at 9% and 12% respectively. S. limacinum SR21 was thought to be a promising resource for microbial DHA production yielding a good level of productivity as well as a simple polyunsaturated fatty acid profile. Received: 26 June 1997 / Received revision: 29 August 1997  / Accepted: 19 September 1997     

Dietary polyunsaturated fatty acids (C18:2 omega6 and C18:3 omega3) do not suppress hepatic lipogenesis

Omega 3 polyunsaturated fatty acids are promoted as beneficial in the prevention of metabolic and cardiovascular diseases. In general, dietary omega 3 fatty acids are derived from plant sources as linolenic acid (LNA, C18:3 omega3) the precursor to eicosapentaenoic acid (EPA, C20:5 omega3) and docosahexaenoic acid (DHA, C22:6 omega3). However, it remains unclear if the polyunsaturated fatty acid (PUFA) LNA can provide the same health benefits as the very long chain highly unsaturated fatty acids (HUFA) EPA and DHA generally derived from oily fish. In this study, mice were fed synthetic diets containing lard (low in PUFA and HUFA), canola oil (to supply PUFA), or a mixture of menhaden and arasco (fish and fungal) oils (to supply HUFA) for 8 weeks. The diets were neither high in calories nor fat, which was supplied at 6%. The lard and canola oil diets resulted in high levels of hepatic triglycerides and cholesterol and elevation of lipogenic gene expression. By comparison livers from mice fed the fish/fungal oil diet had low levels of lipid accumulation and more closely resembled livers from mice fed standard laboratory chow. SREBP1c and PPARgamma gene and protein expression were high in livers of animals fed diets containing lard or canola oil compared with fish/fungal oil. Hepatic fatty acid analyses indicated that dietary PUFA were efficiently converted to HUFA regardless of source. Therefore, differences in hepatic lipid levels and gene expression between dietary groups were due to exogenous fatty acid supplied rather than endogenous pools. These results have important implications for understanding the regulation of hepatic lipogenesis by dietary fatty acids.     

Chylomicron remnant induction of lipid accumulation in J774 macrophages is associated with up-regulation of triacylglycerol synthesis which is not dependent on oxidation of the particles

The influence of chylomicron remnants on lipid accumulation and synthesis and the activity and/or expression of mRNA for some of the key enzymes involved was investigated in the murine macrophage cell line J774. The effects of varying the polyunsaturated fatty acid (PUFA) composition and oxidation state of the remnants were also examined. Chylomicron remnants derived from corn oil (rich in n-6 PUFA) or fish oil (rich in n-3 PUFA) were prepared in vivo and oxidised by incubation with CuSO(4). The native and oxidised remnants caused a marked rise in intracellular triacylglycerol levels, but the rise induced by corn oil remnants (four- to sixfold) was greater than that observed with fish oil remnants (<2-fold). Triacylglycerol synthesis, as measured by the incorporation of [3H]oleate and [3H]glycerol into cellular triacylglycerol, was increased by all four remnant types tested, and corn oil remnants had a significantly greater effect than fish oil remnants. Oxidation of the remnants did not affect the results obtained. Although the incorporation of [3H]oleate into cholesteryl ester by the cells was not significantly changed by any of the four types of remnants tested, the activity and expression of mRNA for acyl Co-enzyme A: cholesterol acyltransferase (ACAT) was increased by corn oil, but not by fish or oxidised corn, remnants. Neutral cholesteryl ester hydrolase (nCEH) activity, however, was also raised by corn oil remnants. These studies indicate that chylomicron remnants induce the accumulation of triacylglycerol in J774 macrophages, and that increased synthesis of triacylglycerol plays a major role in this process. Furthermore, they demonstrate that these effects are enhanced when the remnants are enriched in n-6 PUFA as compared with n-3 PUFA, but not after oxidation of the particles, suggesting that the fatty acid composition of chylomicron remnants may be more important than their oxidation state in their ability to induce foam cell formation.     

发酵法生产多不饱和脂肪酸的研究进展

文章从高产菌株的筛选,发酵条件等方面介绍了微生物发酵生产多不饱和脂肪酸的主要研究进展。同时简要介绍了多不饱和脂肪酸的提取制备技术,并对其发展前景提出了建议。     

Different edible oil beneficial effects (canola oil, fish oil, palm oil, olive oil, and soybean oil) on spontaneously hypertensive rat glomerular enlargement and glomeruli number

We have tested the different edible oil effects on the blood pressure (BP) control and the following glomerular protection. Six groups of 12-week-old male spontaneously hypertensive rats (SHR) (n = 5), have received different edible oils (fish, canola, palm, olive, and soybean) or a placebo by gavage for 13 weeks. Renal cortex was analyzed through light microscopy and stereology. Usual BP increase, glomerulosclerosis, glomerular enlargement, and glomeruli loss in SHR has been prevented (fish, canola and palm oils) or attenuated (olive and soybean oils) by these oil long-term administration. The most favorable effect has been seen in the fish oil administration (source of n-3 polyunsaturated fatty acids, PUFA, eicosapentaenoic and docosahexaenoic acids), followed by both canola and palm oils (source of n-3 PUFA plus n-9 monounsaturated, MUFA, and saturated fatty acid, respectively), and finally both olive and soybean oils (source of n-9 MUFA and n-6 PUFA, respectively).     

Overproduction of free fatty acids in E. coli: implications for biodiesel production

Whereas microbial fermentation processes for producing ethanol and related alcohol biofuels are well established, biodiesel (methyl esters of fatty acids) is exclusively derived from plant oils. Slow cycle times for engineering oilseed metabolism and the excessive accumulation of glycerol as a byproduct are two major drawbacks of deriving biodiesel from plants. Although most bacteria produce fatty acids as cell envelope precursors, the biosynthesis of fatty acids is tightly regulated at multiple levels. By introducing four distinct genetic changes into the E. coli genome, we have engineered an efficient producer of fatty acids. Under fed-batch, defined media fermentation conditions, 2.5 g/L fatty acids were produced by this metabolically engineered E. coli strain, with a specific productivity of 0.024 g/h/g dry cell mass and a peak conversion efficiency of 4.8% of the carbon source into fatty acid products. At least 50% of the fatty acids produced were present in the free acid form.     

High cell density cultivation of a novel Aurantiochytrium sp. strain TC 20 in a fed-batch system using glycerol to produce feedstock for biodiesel and omega-3 oils

A recently isolated Australian Aurantiochytrium sp. strain TC 20 was investigated using small-scale (2 L) bioreactors for the potential of co-producing biodiesel and high-value omega-3 long-chain polyunsaturated fatty acids. Higher initial glucose concentration (100 g/L compared to 40 g/L) did not result in markedly different biomass (48 g/L) or fatty acid (12–14 g/L) yields by 69 h. This comparison suggests factors other than carbon source were limiting biomass production. The effect of both glucose and glycerol as carbon sources for Aurantiochytrium sp. strain TC 20 was evaluated in a fed-batch process. Both glucose and glycerol resulted in similar biomass yields (57 and 56 g/L, respectively) by 69 h. The agro-industrial waste from biodiesel production—glycerol—is a suitable carbon source for Aurantiochytrium sp. strain TC 20. Approximately half the fatty acids from Aurantiochytrium sp. strain TC 20 are suitable for development of sustainable, low emission sources of transportation fuels and bioproducts. To further improve biomass and oil production, fortification of the feed with additional nutrients (nitrogen sources, trace metals and vitamins) improved the biomass yield from 56 g/L (34 % total fatty acids) to 71 g/L (52 % total fatty acids, cell dry weight) at 69 h; these yields are to our knowledge around 70 % of the biomass yields achieved, however, in less than half of the time by other researchers using glycerol and markedly greater than achieved using other industrial wastes. The fast growth and suitable fatty acid profile of this newly isolated Aurantiochytrium sp. strain TC 20 highlights the potential of co-producing the drop-in biodiesel and high value omega-3 oils.     

The effect of dietary fish oils on eicosanoid biosynthesis in peritoneal macrophages is influenced by both dietary N-6 polyunsaturated fats and total dietary fat

Recent research has implicated dietary fish oils in the reduction of eicosanoids formed from arachidonic acid and amelioration of chronic diseases such as coronary heart disease, atherosclerosis and inflammation. Feeding studies were conducted to determine if the efficacy of dietary n-3 polyunsaturated fatty acids (PUFA) from fish oils was influenced by the quantity of n-6 polyunsaturated fatty acids and the total level of fat in the diet. Groups of mice were fed diets composed of 5 and 20% total fat with varying proportions of linoleic acid as a source of n-6 PUFA. Menhaden oil as a source of n-3 PUFA was fed at two levels of n-6 at each level of total fat. Eicosanoid biosynthesis was stimulated and assayed in the mouse peritoneum using zymosan as an inflammatory stimulus. Production of LTE4 and PGE2 was enhanced by increasing n-6 PUFA in the diet at both levels of total fat. High dietary fat significantly suppressed leukotriene (LT) synthesis. Dietary menhaden oil reduced LTE4 and PGE2 synthesis at both levels of dietary n-6 in the low fat study. In animals on 20% dietary fat menhaden oil significantly reduced LT synthesis only at a relatively low dietary n-6 PUFA. On a high n-6 PUFA high fat diets, menhaden oil did not significant affect LTE4 synthesis in response to zymosan stimulation. The results suggest that the effectiveness of fish oils in reducing eicosanoids in response to specific stimulation is influenced by the level of n-6 and the total quantity of fat in the diet.     

五种微绿球藻产油和产多不饱和脂肪酸的研究

从5种微绿球藻中鉴别出4个高产油藻种和1个产油量很低的藻种。4种高产油微绿球藻在平台期油脂含量最高,占细胞干重的57%以上,其中三酰基甘油的含量占细胞干重的32.4%-45.2%。分析5种微绿球藻细胞的脂肪酸组成及4种高产油藻三酰基甘油中的脂肪酸组成,发现在高产油藻中,总的饱和脂肪酸和单不饱和脂肪酸的比例达到95%以上,多不饱和脂肪酸在5%以下,而在产油量很低的微绿球藻中多不饱和脂肪酸比例达45%以上。高产油微绿球藻三酰基甘油的多不饱和脂肪酸含量在4%以下,是生物柴油的优质原料,而产油量低的微绿球藻可用于提取C20:5脂肪酸(EPA)。       

Co‐utilization of acidified glycerol pretreated‐sugarcane bagasse for microbial oil production by a novel Rhodosporidium strain

Acidified glycerol pretreatment is very effective to deconstruct lignocellulosics for producing glucose. Co‐utilization of pretreated biomass and residual glycerol to bioproducts could reduce the costs associated with biomass wash and solvent recovery. In this study, a novel strain Rhodosporidium toruloides RP 15, isolated from sugarcane bagasse, was selected and tested for coconversion of pretreated biomass and residual glycerol to microbial oils. In the screening trails, Rh. toruloides RP 15 demonstrated the highest oil production capacity on glucose, xylose, and glycerol among the 10 strains. At the optimal C:N molar ratio of 140:1, this strain accumulated 56.7, 38.3, and 54.7% microbial oils based on dry cell biomass with 30 g/L glucose, xylose, and glycerol, respectively. Furthermore, sugarcane bagasse medium containing 32.6 g/L glucose from glycerol‐pretreated bagasse and 23.4 g/L glycerol from pretreatment hydrolysate were used to produce microbial oils by Rh. toruloides RP 15. Under the preliminary conditions without pH control, this strain produced 7.7 g/L oil with an oil content of 59.8%, which was comparable or better than those achieved with a synthetic medium. In addition, this strain also produced 3.5 mg/L carotenoid as a by‐product. It is expected that microbial oil production can be significantly improved through process optimization.     

Pilot study of dietary fatty acid supplementation in the treatment of adult periodontitis

The anti-inflammatory effects of both n-3 and n-6 polyunsaturated fatty acids (PUFA) have been demonstrated in vitro and in many disease states, in particular in the treatment of rheumatoid arthritis. The benefit of n-3 PUFA supplementation has been documented in animal models of periodontal inflammation and a trend towards reduced inflammation has been seen in human experimental gingivitis. The purpose of this study was to examine the potential anti-inflammatory effects of PUFA supplementation, by administration of fish oil as a source of the n-3 PUFA, eicosapentaenoic acid, and borage oil as a source of the n-6 PUFA, gamma-linolenic acid (GLA), to adults with periodontitis. Thirty adult human subjects with periodontitis were administered either fish oil 3000 mg daily; borage oil 3000 mg daily; fish oil 1500 and borage oil 1500 mg daily, or placebo. The modified gingival index, the plaque index (PI), periodontal probing depths and beta-glucuronidase levels in gingival crevicular fluid were measured at baseline and after 12 weeks of treatment. Improvement in gingival inflammation was observed in subjects treated with borage oil (P<0.016), with a trend apparent in subjects treated with fish oil or a combination of PUFA. There was no statistically significant improvement in PI, although a trend was apparent in those receiving borage oil. Improvement in probing depth was seen in those subjects treated with either fish oil alone or borage oil alone, but statistical significance was only seen for the comparison of borage oil and placebo (P<0.044). No change was seen in gingival crevicular fluid (GCF) beta-glucuronidase levels. The use of borage oil supplementation, a source of the n-6 PUFA, GLA, can have beneficial effects on periodontal inflammation. n-6 PUFA supplementation seemed to offer more impressive results than either n-3 PUFA supplementation or the combination of lower doses of the two supplements. Additional studies will be necessary to more fully assess the potential of these agents to favorably affect periodontal inflammation.     

Engineering oilseeds to produce nutritional fatty acids

There is a growing body of evidence suggesting that regular consumption of foods rich in omega-3 long chain polyunsaturated fatty acids has multiple positive health benefits. The fats and oils from marine fish contain high contents of these beneficial fatty acids but increased consumer demand has also increased strain on the ability of the world's fisheries to meet demand from wild capture. Many consumers are choosing fish oil supplements or are eating foods that have been complemented with fish oils instead of consuming fish directly. However, removing undesirable odors, flavors and contaminants is expensive. In contrast, oils derived from land plants such as soybean are inexpensive and contaminant free. Recent strides in plant molecular biology now allow the engineering of oilseeds for the production of novel fats and oils, including those synthesized by complex, multigene biosynthetic pathways such as the omega-3 long chain polyunsaturated fatty acids. Given the potential benefits to the environment with regards to overfishing and the health prospects of increased consumption of these healthy fatty acids, producing these fatty acids in oilseeds is a desirable and worthy goal. In this review, we will describe the recent advances in this field along with some of the technical hurdles encountered thus far.     

Optimizing production of polyunsaturated fatty acids in Marchantia polymorpha cell suspension culture

Chlorophyll containing callus cells of Marchantia polymorpha are able to grow under dim illumination in the presence of an organic carbon source and retain the ability to produce polyunsaturated fatty acids (PUFA), including C(20) fatty acids. Highest PUFA production was achieved using 2,4-dichlorophenoxyacetic acid as growth regulator. Inoculum size, illumination intensity, organic carbon source, and ferrous ion are the major factors affecting PUFA productivity. Maximum PUFA productivity is attained under low light intensity, with a photon flux density ca. 20 micromol m(-2) s(-1). Optimal inoculum size and glucose concentration for PUFA production are 8-12% and 20-30 g l(-1), respectively. Ferrous ion can promote PUFA productivity by increasing the intracellular lipid content. Highest productivities for PUFA, arachidonic acid (ARA), and eicosapentaenoic acid (EPA) were 35.0+/-2.1, 6.7+/-0.4 and 6.6+/-0.4 mg l(-1) day(-1), respectively. PUFA production in the M. polymorpha culture is shown to be strongly growth-associated. Environmental stress (osmotic pressure) is ineffective in promoting PUFA productivity. Chitosan, an elicitor, also has no effect on intracellular PUFA content in cultured M. polymorpha cells.     

The Fat-1 Mouse has Brain Docosahexaenoic Acid Levels Achievable Through Fish Oil Feeding

Fat-1 transgenic mice endogenously convert n-6 to n-3 polyunsaturated fatty acids (PUFA). The aims of this study were to test whether a) fish oil feeding can attain similar brain n-3 PUFA levels as the fat-1 mouse, and b) fat-1 mouse brain docosahexaenoic acid (22:6n-3; DHA) levels can be potentiated by fish oil feeding. Fat-1 mice and their wildtype littermates consumed either a 10% safflower oil (SO) or a 2% fish oil and 8% safflower oil chow (FO). Brain total lipid and phospholipid fraction fatty acids were analyzed using GC-FID. Wildtype mice fed FO chow had similar brain levels of DHA as fat-1 mice fed SO chow. Fat-1 mice fed FO chow had similar brain n-3 PUFA levels as fat-1 mice fed SO chow. In conclusion, brain levels of DHA in the fat-1 mouse can be obtained by and were not further augmented with fish oil feeding.     

The effects of n-3 and n-6 polyunsaturated fatty acids on plasma lipids and fatty acids of treated phenylketonuric children

Dietary-treated phenylketonuric patients (PKUs) display low levels of long-chain polyunsaturated fatty acids (PUFA) in plasma lipids. In a 6-month clinical trial we observed a decrease of triglycerides and an increase of n-3 long-chain PUFA in plasma of PKUs supplemented with fish oil, while no major differences in respect to the baseline values were found in a group supplemented with blackcurrant oil. A more complete source of long-chain PUFA of both the n-6 and n-3 series should be investigated for dietary supplementation of PKU patients.     

Eicosapentaenoic and docosahexaenoic acids enriched polyunsaturated fatty acids from the coastal marine fish of Bay of Bengal and their therapeutic value

Eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) enriched polyunsaturated fatty acids (PUFA) significantly present in marine fish oil emerge as preventive agents for combating many health problems specially in chronic or metabolic disorders. The fish in the coastal area of Bay of Bengal has remained unexplored with respect to EPA/DHA enriched PUFA content in its oils, although it may be a potential source in harnessing the health benefit. In this study, seven varieties of the coastal fish were analysed for the content of EPA/DHA. The one locally known as lotte, (Harpadon nehereus) though has low content of total lipids, was found to have high EPA/DHA in its oil. The phospholipids rich fraction was extracted from the total fish oil. The EPA/DHA enriched PUFA was isolated to investigate the potential use for health benefits. EPA/DHA is found to act as protective agent against mercury poisoning studied in cell culture as well as in animal mode. It is found to be highly preventive in diabetes. The lotte is available in the coastal area of Bay of Bengal adjoining West Bengal, India in large scale and it is the first report showing EPA/DHA enriched PUFA in these fish oil that can be availed to harness in important health benefits.     

Effect of saturated, omega-3 and omega-6 polyunsaturated fatty acids on myocardial infarction

Dietary fatty acids have cholesterol lowering, antiatherogenic, and antiarrhythmic properties that decrease the risk of myocardial infarction (MI). This study was designed to study the effects of various oils rich in either polyunsaturated (omega-3 or omega-6) fatty acids (PUFA) or saturated fatty acids (SFA) on the severity of experimentally induced MI. Male albino Sprague-Dawley rats (100-150 g; n = 20) were fed diets enriched with fish oil (omega-3 PUFA), peanut oil (omega-6 PUFA), or coconut oil (SFA) for 60 days. Experimental MI was induced with isoproterenol. Mortality rates; serum enzymes aspartate amino transferase; alanine amino transferase; creatine phosphokinase (CPK); lipid profiles in serum, myocardium, and aorta; peroxide levels in heart and aorta; activities of catalase and superoxide dismutase; and levels of glutathione were measured. The results demonstrated that mortality rate, CPK levels, myocardial lipid peroxides, and glutathione levels were decreased in the omega-3 PUFA treated group. Maximum increase in parameters indicative of myocardial damage was seen in the coconut oil group. These findings suggest that dietary omega-3 PUFA offers maximum protection in experimentally induced MI in comparison to omega-6 PUFA and SFA enriched diets. SFA was found to have the least protective effect.     

Antarctic microorganisms as source of the omega-3 polyunsaturated fatty acids

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are long-chain polyunsaturated fatty acids (PUFAs) that belong to the omega-3 group. They are essential fatty acids found in phospholipid of cell membranes. There is strong evidence that these nutrients may also favorably modulate many diseases. Primary sources of omega-3 PUFAs in the human diet are fish and fish-derived products. The fishing industry worldwide, however, is becoming unable to satisfy the growing demand for these PUFAs. A promising cost-effective alternative source of PUFAs is bacterial production. We identified 40 Antarctic marine bacterial isolates by 16S rRNA gene sequence analysis. Fifteen genera in three phyla were represented in the collection. Isolates were tested for ability to produce EPA using a method in which their ability to reduce 2,3,5-triphenyltetrazolium chloride (TTC) is determined and by gas chromatography coupled to mass spectrometry (GC–MS). All isolates could reduce TTC, and GC–MS analysis showed that four produced EPA and that six produced DHA. We show for the first time that isolates identified as Cellulophaga, Pibocella and Polaribacter can produce EPA and DHA, only DHA or only EPA, respectively. One isolate, Shewanella sp. (strain 8-5), is indicated to be a good candidate for further study to optimize growth and EPA production. In conclusion, a rapid method was tested for identification of new EPA producing strains from marine environments. New EPA and DHA producing strains were found as well as a potentially useful PUFA production strain.     

Effects of dietary n-3 fatty acids on the composition of cholesteryl esters and triglycerides in plasma and liver perfusate of the rat

The effects of polyunsaturated fatty acids of the omega-3 family (PUFA n-3), (addition of fish oil), on the molecular composition of cholesteryl esters and triglycerides in plasma and liver perfusate of rats were studied. Rats fed a diet rich in saturated fatty acids (addition of lard) served as controls. Supplemention with PUFA n-3 not only decreases the plasma concentrations of free cholesterol, cholesteryl esters, and triglycerides, it also significantly alters the plasma composition of cholesteryl esters and triglycerides. Analyses of liver perfusate indicate a decrease in triglycerides secretion by in vitro perfused liver and reciprocal changes in relative contents of cholesteryl esters fractions with C(16) and C(20) acyl chains. This finding may be a result of chain-shortening of long-chain fatty acids probably in peroxisomal beta-oxidative system. Alterations in plasma cholesteryl esters and triglycerides composition of the fish oil group could be affected further by additional factors such as increased plasma cholesterol esterification activity and presence of triglyceride species of intestinal origin.     

Oleaginous yeast Meyerozyma guilliermondii shows fermentative metabolism of sugars in the biosynthesis of ethanol and converts raw glycerol and cheese whey permeate into polyunsaturated fatty acids

We studied the biotechnological potential of the recently isolated yeast Meyerozyma guilliermondii BI281A to produce polyunsaturated fatty acids and ethanol, comparing products yields using glucose, raw glycerol from biodiesel synthesis, or whey permeate as substrates. The yeast metabolism was evaluated for different C/N ratios (100:1 and 50:1). Results found that M. guilliermondii BI281A was able to assimilate all tested substrates, and the most efficient conversion obtained was observed using raw glycerol as carbon source (C/N ratio 50:1), concerning biomass formation (5.67 g·L⁻¹) and lipid production (1.04 g·L⁻¹), representing 18% of dry cell weight. Bioreactors experiments under pH and aeration-controlled conditions were conducted. Obtained fatty acids were composed of ~67% of unsaturated fatty acids, distributed as palmitoleic acid (C_16:1, 9.4%), oleic acid (C_18:1, 47.2%), linoleic acid (C_{18:2 n−6}, 9.6%), and linolenic acid (C_{18:3 n−3}, 1.3%). Showing fermentative metabolism, which is unusual for oleaginous yeasts, M. guilliermondii produced 13.7 g·L⁻¹ of ethanol (yields of 0.27) when growing on glucose medium. These results suggest the promising use of this uncommonly studied yeast to produce unsaturated fatty acids and ethanol using cheap agro-industrial residues as substrates in bioprocess.