The predominance of polyunsaturated fatty acids in the butterfly Morpho peleides before and after metamorphosis

We hypothesized that the polyunsaturated fatty acids of the butterfly were probably derived from the diet and that there might be a great loss of body fat during metamorphosis. To substantiate these hypotheses, we analyzed the fatty acid composition and content of the diet, the larva, and the butterfly Morpho peleides. Both the diet and the tissues of the larva and butterfly had a high concentration of polyunsaturated fatty acids. In the diet, linolenic acid accounted for 19% and linoleic acid for 8% of total fatty acids. In the larva, almost 60% of the total fatty acids were polyunsaturated: linolenic acid predominated at 42% of total fatty acids, and linoleic acid was at 17%. In the butterfly, linolenic acid represented 36% and linoleic acid represented 11% of total fatty acids. The larva had a much higher total fatty acid content than the butterfly (20.2 vs. 6.9 mg). Our data indicate that the transformation from larva to butterfly during metamorphosis drastically decreased the total fatty acid content. There was bioenhancement of polyunsaturated fatty acids from the diet to the larva and butterfly. This polyunsaturation of membranes may have functional importance in providing membrane fluidity useful in flight.     

Changes in fatty acids,amino acids and carbon/nitrogen biomass during nitrogen starvation of ammonium- and nitrate-grownIsochrysis galbana

Growth of cells ofIsochrysis galbana with either nitrate or ammonium as the N-source, and the effects of subsequent N-starvation of these cells, were compared. During exponential N-sufficient growth nitrate-grown cells had double the fatty acid content of the ammonium-grown cells but lower concentrations of a few amino acids. Following resuspension in N-free medium the fatty acid content of the ammonium-grown cells increased to that of the nitrate-grown cells, but there was no further increase in fatty acid content on a C-biomass or cellular basis during the following 4 days for either culture. Fatty acid synthesis was continuous during N-starvation, while it occurred during the light-phase only in exponential growth. The proportion of 18:1n9 fatty acid increased from 10 to 25% total fatty acids during N-starvation. Intracellular free amino acid content decreased in a similar manner in both cultures on N-starvation, the ratio of intracellular free amino-N/cell-C falling more rapidly than overall cellular N/C. It was concluded that optimal amino acid and fatty acid content would be attained by growth in the presence of excess nitrate. Measurements of chlorophyll and carotenoid content and ofin vivo fluorescence indicated that these parameters had potential for monitoring the C and N biomass in cultures grown under relatively constant (not necessarily continuous) illumination.     

光质对湛江等鞭金藻生长和脂肪酸组成的影响

在气升式光生物反应器中研究不同光质光影响湛江等鞭金藻的生长。结果表明,藻细胞密度的大小顺序为：红光〉白光＋红光、白光〉白光＋蓝光＋红光〉白光＋蓝光〉蓝光。蓝光下多不饱和脂肪酸百分含量最高,占总脂肪酸的50．01％。白光下总单不饱和脂肪酸和总饱和脂肪酸含量最高,占总脂肪酸的24．19％和27．46％。多不饱和脂肪酸中C18：4。．3含量最高,占总脂肪酸的20．3％-23.3％,最高值出现在蓝光下;其次为C22：6n-3（DHA）,占总脂肪酸的10．2％-12．3％,在蓝光和白光＋蓝光中较高;而C18：2n-6和C18：3n-3均以红光下的为最高,分别达3．11％和8．04％。     

Fatty acid profiles of cells from the insect cell line iprl-21 (Spodoptera frugiperda) and of the tissue culture medium after repeated use

Summary When IPL-1 medium was used for three serial incubations of cells of the IPRL-21 insect cell line (Spodoptera frugiperda, J. E. Smith) at least 23 fatty acids were identified from the media and/or from the cells. During the first incubation only negligible changes occurred in the total fatty acid content of the medium, but after the second and third incubations the total content decreased. Seven of the 23 fatty acids (palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, and arachidonic acids) comprised 92% of the total fatty acid content, but the specific concentrations varied after each 7-day incubation. During the first incubation, the concentration of the monoene fatty acids increased, and the concentration of the more highly unsaturated fatty acids decreased. During the second and third serial incubations, the specific concentrations of all fatty acids decreased, with the exception of palmitoleic acid. These changes in the total fatty acid content and in the specific concentration of individual fatty acids in the cell indicated uptake of fatty acids from the medium and/or cellular lipid biosynthesis. The fatty acid content of the cells differed during the active growth phase and the stationary phase.     

The influence of carbon source on the level and composition of ceramides of the Candida lipolytica yeast

Candida lipolytica yeast was grown batchwise on two different carbon sources, glucose and n-hexadecane. Free ceramides were quantitatively isolated from sphingolipid fractions of total lipids by a combination of column chromatography and preparative thin-layer chromatography. Their composition, after acid methanolysis, was analysed by gas-liquid chromatography. The ceramide content accounted for 2.6% of the total cell lipids in hexadecane-grown cells, which was 1.5 times higher than in glucose-grown cells. The fatty acid composition of ceramides was characterized by the predominance of fatty acids shorter than 20 carbon atoms and by high concentrations of fatty acids with 16 carbon atoms after growth on both carbon sources. The dominant fatty acid was hydroxylated 16:0 in the glucose-grown cells and 16:0 in the hexadecane-grown cells. The striking finding was the low degree of fatty acid hydroxylation and relatively high proportion of odd-numbered fatty acids in ceramide of the n-hexadecane-grown cells. The ceramides contained an unusual long-chain base composition. In hexadecane-grown cells more than 60% of the long-chain bases were C₁₉ phytosphingosine. In glucose-grown cells more than one-half of the total long-chain bases were tetrahydroxy bases, 4,5-dihydroxysphinganine and 4,5-dihydroxyeicosasphinganine. Received: 20 April 1998 / Received revision: 10 July 1998 / Accepted: 29 July 1998     

Fatty Acid Compositions of Triglyceride and Phospholipid from Candida tropicalis Grown on n-Alkanes

The content of total cellular lipid of Candida tropicalis grown on a mixture of n-alkanes (C₁₀–C₁₈) was about 20% of the dry cell weight at the exponential growth phase and 14% at the early stationary phase. Phospholipid corresponded to approximately 70 % of the total lipid independent of the growth phases. The composition of cellular lipid classes did not change significantly during the growth. On the other hand, a drastic time-course change in fatty acid composition was observed. The proportion of odd-chain fatty acids, one of the most specific cellular components of the yeast grown on the n-alkane mixture, increased in both phospholipid and triglyceride along with the yeast growth. In the meantime, the proportion of polyunsaturated fatty acids varied markedly during the course of cultivation, showing a peak at the early growth phase. The high content of polyunsaturated fatty acids at the early stages of growth correlated to the contents of these acids in phospholipid rather than in triglyceride.     

Effect of exogenous sterols on the growth and fatty acid composition of the oomycetePythium debaryanum

Exogenous ergosterol and cholesterol were found to affect the growth and lipogenesis of the oomycete fungusPythium debaryanum, which is unable to synthesize de novo steroid compounds. These sterols stimulated the growth of the fungus during its submerged cultivation in glucose-peptone medium. This was accompanied by the shortening of the lag phase, the lengthening of the period of active growth, and by a 3.7-or 4.3-fold increase in the maximum biomass in response to the addition of ergosterol or cholesterol, respectively. In the presence of ergosterol, the cellular content of polyenoic fatty acids increased, and the relative content of eicosapolyenoic fatty acids reached 31.4% of the total amount of fatty acids in cells. Conversely, cholesterol decreased the cellular content of polyenoic acids, and the relative content of eicosapolyenoic acids fell to 19.6% of the total amount of fatty acids. It may be inferred that exogenous sterols enhance the yield of pharmacologically active polyenoic acids because of the growth stimulation.     

Composition of Fatty Acids and Carbohydrates in Leptospira

The fatty acid and monosaccharide composition of four pathogenic and two saprophytic strains of Leptospira was analyzed by gas chromatography (GC) and GC-mass spectrometry. Among the fatty acids, palmitic acid was most abundant and constituted 30 to 50% of the total fatty acids. Even-numbered unsaturated acids including octadecenoic, hexadecenoic, octadecadienoic, and tetradecadienoic acids comprised 40 to 60% of the total fatty acids. Tetradecanoic acid was about 5% in saprophytic strains, but 1% or less in pathogenic strains. The amount of chloroform-methanol extract of L. biflexa strain Ancona was 14 to 20% of the dry weight of the cell. Tetradecadienoic acid was found in the chloroform-methanol insoluble fraction, suggesting the presence of the acid in a bound form. GC analysis of monosaccharides revealed the existence of arabinose, xylose, rhamnose, mannose, galactose, glucose, glucosamine, and muramic acid in the cells. Among the neutral sugars, glucose was a minor component and was especially low in pathogenic strains. Total pentose content was about two to three times greater than total hexose.     

Lipids and fatty acids in muscle, liver and skin of three edible fish from the Senegalese coast: Sardinella maderensis, Sardinella aurita and Cephalopholis taeniops

Lipid content and fatty acid composition were determined in three species of edible fish caught in Senegalese waters during the upwelling season (January, 1993). Sardinella maderensis and Sardinella aurita are fat fish containing more than 5% (fresh wt.) of lipids, whereas Cephalopholis taeniops is a lean fish with approximately 1% of lipids. Skin, liver and muscle were studied for each fish species. About 40 fatty acids were identified by GC and GC/MS as methyl esters and N-acyl pyrrolidides. Palmitic acid was the main acid in the muscle and skin of all samples studied (20-33% of total fatty acids). Oleic acid was the main fatty acid in the liver of S. maderensis (27.2%+/-0.1) and S. aurita (44.7%+/-0.1). Arachidonic acid was a minor component in all samples. The flesh (muscle) of the three fish species contained high concentrations of omega3 polyunsaturated fatty acids (PUFA), ranging from 16.0 to 29.1% and including 20:5 omega3 (eicosapentaenoic acid, EPA) and 22:6 omega3 (docosahexaenoic acid, DHA) acids as major components. These two acids together accounted for 24.7%+/-0.1 and 12.9%+/-0.1 of total acids in the skin of S. maderensis and S. aurita, respectively. The percentages of PUFA found in the fish studied were very similar to those in fish used commercially as sources of PUFA. Muscle sterols, which accounted for 9-11% of total lipids, consisted mainly of cholesterol (up to 97% of total sterols).     

Effects of nitrogen source and concentration on growth rate and fatty acid composition of Ellipsoidion sp. (Eustigmatophyta)

In order to study the effects of different nitrogen source and concentrationon the growth rate and fatty acid composition, a marine microalga Ellipsoidion sp. with a high content of eicosapentaenoic acid (EPA) wascultured in media with different nitrogen sources and concentrations.During the pre-logarithmic phase, the alga grew faster with ammoniumas N source than with nitrate, but the reverse applied during thepost-logarithmic phase. The alga grew poorly in N-free mediumor medium with urea as the sole N source. In the same growth phase,ammonium medium resulted in higher yield of total lipid, but the EPA yielddid not differ significantly different from that using nitrate medium. Themaximum growth rate occurred in medium containing 1.28 mmolL^-1 sodium nitrate, while maximum EPA and total lipid contents werereached at 1.92 mmol L^-1, when EPA accounted for 27.9% totalfatty acids. The growth rate kept stable when NH₄Cl ranged from0.64 to 2.56 mmol L^-1, and the maximum content of total lipidand EPA occurred in the medium with 2.56 mmol L^-1NH₄Cl. The EPA content was higher in the pre- thanpost-logarithmic phase, though the total lipid content was lower. Thehighest EPA content expressed as percent total fatty acid was 27.9% innitrate medium and and 39.0% in ammonium medium.     

BIOCHEMICAL COMPOSITION AND FATTY ACID CONTENT OF FILAMENTOUS NITROGEN-FIXING CYANOBACTERIA

The biochemical composition and fatty acid content of twelve strains of filamentous, heterocystous, nitrogen-fixing cyanobacteria have been determined. When grown under diazotrophic conditions, protein, carbohydrate, lipid, and nucleic acids comprised 37–52%, 16–38%, 8–13%, and 8–11% of the dry weight, respectively. The presence of a combined nitrogen source resulted in an increase in the protein content of the cells and a decrease in the levels of lipids and carbohydrates, although biomass productivity was not affected significantly. Biochemical composition also changed during culture growth, with the highest levels of proteins and lipids occurring as the culture entered stationary phase, whereas the highest levels of carbohydrate and nucleic acids were found during the exponential phase. Total fatty acid levels in the strains assayed ranged between 3 and 5.7% of the dry weight. With regard to fatty acid composition, all strains showed high levels of polyunsaturated fatty acids (PUFAs) and saturated fatty acids (SAFAs), with values of 24–45% and 31–52% of total fatty acids, respectively, whereas the levels of monounsaturated fatty acids (MUFAs) were in general lower (11– 32%). Palmitic acid (16:0) was the most prevalent SAFA, whereas palmitoleic (16:1n- 7) and oleic acid (18:1n-9) were the most abundant MUFAs in all the strains. Among PUFAs, γ-linolenic acid (GLA, 18:3n-6) was present at high levels (18% of total fatty acids) in Nostoc sp. (Chile) and at lower levels (3.6% of total fatty acids) in Anabaenopsis sp. The presence of GLA has not been previously reported in these genera of cyanobacteria. The rest of the strains exhibited high levels (12–35% of total fatty acids) of α-linolenic acid (ALA, 18:3n-3). Linoleic acid (18:2n-6) was also present at a substantial level in most of the strains. Eicosapentaenoic acid (EPA, 20:5n-3) was also detected in Nostoc sp. (Albufera). Some filamentous nitrogen-fixing cyanobacteria therefore represent potential sources of commercially interesting fatty acids.     

Biochemical composition of Tunisian Nigella sativa L. at different growth stages and assessment of the phytotoxic potential of its organic fractions

The present study was conducted to study some biochemical characteristics of Tunisian Nigella sativa at different developmental stages of plant growth (vegetative, flowering and fruiting stages) and to screen the chemical constituents and the phytotoxic activity of their organic extracts on lettuce (Lactuca sativa L.). The GC–MS analysis of petroleum ether fractions revealed that N. sativa seeds were rich in linoleic acid (58% of total fatty acids), oleic acid (22% of total fatty acids) and palmitic acid (12% of total fatty acids). The fatty acid composition of aerial parts showed an increase in the level of saturated fatty acids accompanied by a concomitant decrease of polyunsaturated fatty acids levels during the developmental stage. The phytochemical investigation showed that among the organic extracts, the methanolic extract from aerial parts harvested at the fruiting stage contained the highest amounts of phenolic and flavonoid compounds. The phytotoxic study revealed that N. sativa negatively affected the growth of lettuce plants. This effect was largely dependent on the developmental stage at which material was collected and the nature of extracting solvent. The methanolic extract of aerial parts harvested at the vegetative stage was the most active on seedling growth of lettuce.     

Total lipid and fatty acid composition of seaweeds for the selection of species for oil‐based biofuel and bioproducts

We investigated the potential of seaweeds as feedstock for oil‐based products, and our results support macroalgae (seaweeds) as a biomass source for oil‐based bioproducts including biodiesel. Not only do several seaweeds have high total lipid content above 10% dry weight, but in the brown alga Spatoglossum macrodontum 50% of these lipids are in the form of extractable fatty acids. S. macrodontum had the highest fatty acid content (57.40 mg g^?1 dw) and a fatty acid profile rich in saturated fatty acids with a high content of C18:1, which is suitable as a biofuel feedstock. Similarly, the green seaweed Derbesia tenuissima has high levels of fatty acids (39.58 mg g^?1 dw), however, with a high proportion of PUFA (n‐3) (31% of total lipid) which are suitable as nutraceuticals or fish oil replacements. Across all species of algae the critical parameter of fatty acid content (measured as fatty acid methyl esters, FAME) was positively correlated (R² = 0.67) with total lipid content. However, the proportion of fatty acids to total lipid decreased markedly with total lipid content, generally between 30% and 50%, making it an inaccurate measure of the potential to identify seaweeds suitable for oil‐based bioproducts. Finally, we quantified within species variation of fatty acids across locations and sampling periods supporting either environmental effects on quantitative fatty acid profiles, or genotypes with specific quantitative fatty acid profiles, thereby opening the possibility to optimize the fatty acid content and quality for oil production through specific culture conditions and selective breeding.     

Production of Dihomo-γ-Linolenic Acid by a Δ5-Desaturase-Defective Mutant of Mortierella alpina 1S-4

A mutant, which has low Δ5-desaturase activity, of an arachidonic acid-producing fungus, Mortierella alpina 1S-4, was shown to be a novel potent producer of dihomo-γ-linolenic acid (DHGA). On submerged culture under optimal conditions for 6 days at 28°C in a 10-liter fermentor, the mutant produced 3.2 g of DHGA per liter of culture broth (123 mg/g of dry mycelia), which accounted for 23.4% of the total mycelial fatty acids. Mycelial arachidonic acid amounted to only 19 mg/g of dry mycelia (0.5 g/liter of culture broth), which accounted for 3.7% of the total mycelial fatty acids. The other major mycelial fatty acids were palmitic acid (11.0%), stearic acid (12.8%), oleic acid (22.7%), linoleic acid (8.9%), γ-linolenic acid (6.5%), and lignoceric acid (7.8%). More than 97 mol% of the DHGA produced was found in the triglyceride fraction irrespective of the growth temperature employed (12 to 28°C).     

Changes of Lipid Composition with Growth Phase of Cryptococcus neoformans

Qualitative and quantitative profiles of phospholipids, neutral lipids, and fatty acid composition in Cr. neoformans during the growth phase were investigated in relation to pyrophosphatidic acid. A marked increase of the total lipid content, which depended on the accumulation of triglyceride in yeast cells with the growth, was observed. The total phospholipid contents in yeast cells remained almostly constant during the exponential phase and slightly decreased in the stationary phase. The major phospholipids of this yeast were phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, and cardiolipin, the next groups being pyrophosphatidic acid, phosphatidic acid, lysophos-phatidylcholine, and unidentified components. The amounts of phosphatidylcholine, phosphatidylinositol, and cardiolipin were fairly constant throughout the growth phase, but the amount of phosphatidylethanolamine increased and that of phosphatidylserine decreased with progressive growth. The pyrophosphatidic acid contents were 0.9~0.7% for total phospholipid during the growth phase. The major fatty acids of pyrophosphatidic acid were C_16:0, C_18:1, and C_18:2 acids. The changing patterns of fatty acid composition in pyrophosphatidic acid through the growth phase closely resembled that of phosphatidic acid, which contained larger amounts of C_18:1 acid (35~45%) than C_16:0 acid (30~25%) and C_18:2 acid (30~25%). Phosphatidylserine and phosphatidylinositol contained considerable amounts of saturated fatty acid (C_16:0 acid, more than 55%). On the other hand, phosphatidylcholine, phosphatidylethanolamine, and cardiolipin contained extremely large amounts of unsaturated fatty acid (C_18:1 and C_18:2 acid, 85ç90%).     

Characterizations of Phospholipids from Paramecium tetraurelia Cells and Cilia*,†

Phospholipids from Paramecium tetraurelia strains 51s and d,95 cultures and isolated cilia were characterized. The following classes of phospholipids were identified in whole cell lipids: the 1-alkyl-2–acylglyceryl and the 1,2–diacylglyceryl forms of phosphonylethanolamine, phosphorylethanolamine. and phosphorylcholine; cardiolipin: ceramide aminoethylphosphonate and 5 other sphingolipids: phosphatidylserine; phosphatidylinositol; and lyso derivatives of the major glycerophospholipids. Cilia lipids were rich in ether lipids, phosphonolipids. and sphingolipids. Net lipid biosynthesis did not occur, as determined by the weight of lipids extracted from culture medium compared with the weight of lipids extracted from culture medium and ciliates after 7 days of growth. Total lipids/cell decreased with culture age. changes in the neutral lipid fraction accounting for the major decrease. Phospholipid class distributions changed with culture age—the glyceryl phosphorylethanolamine and choline content of cells decreased, while the glyceryl ohosphonylethanolamine content remained relatively constant: hence, the ratio of phosphonolipids to total phospholipids increased. All fatty acids observed in total lipids from cells and cilia were also present in the glycerophospholipids. Total lipids from cilia contained a greater percent of polyunsaturated fatty acid than those of whole cells. Whole cells and cilia glyceryl phosphonolipids contained up to 93% eicosatetraenoic plus eicosapentaenoic fatty acids. The enrichment of phosphonolipids in cilia accounted for most of the polyunsaturated fatty acid enrichment observed in cilia total lipids. The fatty acid composition of all major whole cell glycerophospholipid classes changed dramatically with culture age, while only small changes occurred in cilia glycerophospholipid fatty acids.     

Production of Dihomo-gamma-Linolenic Acid by a Delta5-Desaturase-Defective Mutant of Mortierella alpina 1S-4

A mutant, which has low Delta5-desaturase activity, of an arachidonic acid-producing fungus, Mortierella alpina 1S-4, was shown to be a novel potent producer of dihomo-gamma-linolenic acid (DHGA). On submerged culture under optimal conditions for 6 days at 28 degrees C in a 10-liter fermentor, the mutant produced 3.2 g of DHGA per liter of culture broth (123 mg/g of dry mycelia), which accounted for 23.4% of the total mycelial fatty acids. Mycelial arachidonic acid amounted to only 19 mg/g of dry mycelia (0.5 g/liter of culture broth), which accounted for 3.7% of the total mycelial fatty acids. The other major mycelial fatty acids were palmitic acid (11.0%), stearic acid (12.8%), oleic acid (22.7%), linoleic acid (8.9%), gamma-linolenic acid (6.5%), and lignoceric acid (7.8%). More than 97 mol% of the DHGA produced was found in the triglyceride fraction irrespective of the growth temperature employed (12 to 28 degrees C).     

Seasonal variation in fatty acid composition of silver pomfrets,Pampus argenteus (Euphrasen), in Kuwait waters

Proximate and fatty acid composition of wild silver pomfrets, Pampus argenteus, were studied in Kuwait waters for a period of 1 year (November 2007–October 2008) to see whether there were any seasonal compositional differences between males and females. Ten adults (five males, five females) were sampled each month during (i) Pre‐spawning (March–May), (ii) Spawning (June–August), (iii) Post‐spawning (September–November), and (iv) Winter (December–February). Both sexes had significantly (P < 0.05) higher whole body moisture and lower crude protein and lipid contents in winter compared to the respective males and females sampled in other seasons. However, females had significantly higher (9.1%) lipid content during the pre‐spawning season than females in other seasons (7.0–8.2%). The most abundant fatty acid in whole body lipid in both sexes was C16 followed by C18:1n‐9, which accounted for about 31–35% and 22–24% of total lipids, respectively. Males in the pre‐spawning and spawning seasons had significantly higher total monosaturated fatty acids (MUFA) than males and females in post‐spawning and winter. Males had significantly higher total polyunsaturated fatty acids (PUFA) during post‐spawning seasons than females in pre‐spawning and winter seasons. However, there were no significant differences (P > 0.05) in total saturated fatty acids (SFA), PUFA, EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid) or n‐3/n‐6 ratios between respective males and females in different seasons. Livers in males had significantly (P < 0.05) higher MUFA, SFA, PUFA, EPA and DHA than respective females in all months during the spawning season. Female gonads had significantly (P < 0.05) higher MUFA and PUFA but lower SFA content than males in different months during the spawning season. In contrast to the liver, the gonad DHA content and n‐3/n‐6 ratios in females were significantly higher than in males. The gonads from both sexes contained more than double the amount of EPA present in liver; in the case of DHA this was more than three‐fold higher in female gonads, but not in males. Thus, the presence of higher proportions of PUFA, EPA and DHA in gonads, particularly in eggs of silver pomfret, indicates their need for these fatty acids, which may be used as a guideline for dietary essential n‐3 fatty acid requirements for feed formulation of this species. A higher content of DHA in eggs also indicates the higher requirement for DHA in the broodstock diet of silver pomfret.     

Development of High‐Level Omega‐3 Eicosapentaenoic Acid (EPA) Production from Phaeodactylum tricornutum

Phaeodactylum tricornutum is a lipid‐rich marine diatom that contains a high level of omega‐3 polyunsaturated fatty acids, especially eicosapentaenoic acid (EPA). In an effort to reduce costs for large‐scale cultivation of this microalga, this study first established a New BBM medium (0.3 x strength BBM with only 3% of the initial phosphate level) to replace the traditional F/2 medium. Phaeodactylum tricornutum could grow in extremely low phosphate concentrations (25 µM), without compromising the EPA content. In the presence of sea salts, silicate addition was not necessary for high rate growth, high EPA content, or lipid accumulation in this species. Using urea as the sole nitrogen source tended to increase EPA contents per dry biomass (by 24.7%) while not affecting growth performance. The use of sea salts, rather than just sodium chloride, led to significantly improved biomass yields (20% increase) and EPA contents of total fatty acid (46–52% increase), most likely because it supplied sufficient essential elements such as magnesium. A salinity level of 35 led to significantly higher biomass yields compared with 20, but salinity had no significant influence on EPA content. EPA became the dominant fatty acid with average levels of 51.8% of total fatty acids during the exponential growth phase at 20 ppt in New BBM medium with sea salts.     

The effect of lipids and temperature on the physiology and growth ofVolvariella volvacea

Vegetable oils promoted mycelial growth ofVolvariella volvacea. Ethyl esters of major components of saponified fatty acids (palmitic, stearic, oleic and linoleic acid) from vegetable oils were stimulatory. The stimulatory effect of these fatty acids varied with concentration and degree of unsaturation; relatively high concentrations being inhibitory. Mycelial growth appears to be promoted by low concentrations of fatty acids. Supplementation of growth medium with sunflower oil altered membrane permeability and this resulted in an increased uptake of glucose. The total mycelial lipids accounted for only 30% of consumed lipids, the remainder being metabolized. The failure of the fungus to adjust the degree of unsaturation in membrane lipids when it was transferred to 0°C may partially explain its susceptibility to chilling injury.