Purification and structure analysis of mycolic acids in <Emphasis Type="Italic">Corynebacterium glutamicum</Emphasis>

Corynebacterium glutamicum is widely used for producing amino acids. Mycolic acids, the major components in the cell wall of C. glutamicum might be closely related to the secretion of amino acids. In this study, mycolic acids were extracted from 5 strains of C. glutamicum, including ATCC 13032, ATCC 13869, ATCC 14067, L-isoleucine producing strain IWJ-1, and L-valine producing strain VWJ-1. Structures of these mycolic acids were analyzed using thin layer chromatography and electrospray ionization mass spectrometry. More than twenty molecular species of mycolic acid were observed in all 5 strains. They differ in the length (20–40 carbons) and saturation (0–3 double bonds) of their constituent fatty acids. The dominant species of mycolic acid in every strain was different, but their two hydrocarbon chains were similar in length (14–18 carbons), and the meromycolate chain usually contained double bonds. As the growth temperature of cells increased from 30°C to 34°C, the proportion of mycolic acid species containing unsaturated and shorter hydrocarbon chains increased. These results provide new information on mycolic acids in C. glutamicum, and could be useful for modifying the cell wall to increase the production of amino acids.     

Nuclear Deoxyribonucleic Acid Metabolism and Membrane Fatty Acid Content Related to Chilling Resistance in Germinating Cotton (Gossypium barbadense)

Chilling damage was examined in the chilling-sensitive plant Gossypium barbadense. Between 30 and 36 h of germination at 34°C, the seedlings are extremely sensitive to temperatures below 10°C. The initiation of chilling damage by exposure to 2°C for 5 h during the sensitive period resulted in a large reduction in DNA synthesis. The reduction was correlated with a reduced efficiency of nuclear DNA polymerase activity. Comparing a more chilling resistant genotype to a more sensitive variety indicated that the resistant genotype nuclear DNA polymerase activity is more efficient when exposed to a chilling stress. Resistance was also correlated with a higher degree of unsaturated fatty acid content in the nuclear membranes of the resistant variety.     

Regulation of the synthesis of unsaturated fatty acids by growth temperature in Bacillus subtilis

Bacillus subtilis synthesizes, almost exclusively, saturated fatty acids, when grown at 37° C. When cultures were transferred from 37° C to 20° C, a chloramphenicol- and rifampicin-sensitive synthesis of a C-16 unsaturated fatty acid was observed. Synthesis of this compound reached a plateau after 5 h at 20° C, reaching levels of 20% of the total fatty acid content. [¹⁴C]-labelled fatty acids attached as thioesters to acyl-carriers compounds, such as coenzyme A (CoA) or acyl-carrier protein (ACP) synthesized de novo by glycerol-requiring auxotrophs deprived of glycerol to arrest phospholipid synthesis, could not be desaturated at 20° C. Desaturation of these fatty acids was readily observed when glycerol was restored to the cultures allowing resumption of transfer of acyl-moieties from acyl-thioesters to phospholipid. It was also observed that depletion of the pools of CoA and ACP by starvation of pantothenate auxotrophs had no effect on the observed synthesis of unsaturated fatty acid at 20° C. The overall results indicate that synthesis of unsaturated fatty acids in B. subtilis is a cold-inducible process and that phospholipids are obligate intermediates in this fatty acid desaturation pathway.     

Interpopulation variability on embryo growth,seed dormancy break,and germination in the endangered Iberian daffodil Narcissus eugeniae (Amaryllidaceae)

The main goal of the study was to assess germination requirements in a threatened daffodil to elaborate a detailed protocol for plant production from seeds, a key tool for conservation. Experiments were carried out both in the laboratory and outdoor conditions. In Pseudonarcissi section, endemic Iberian species of Narcissus studied heretofore have different levels of morphophysiological dormancy (MPD). Embryo length, radicle emergence, and shoot emergence were analyzed to determine the level of MPD. Both interpopulational variability and seed storage duration were also studied. Mean embryo length in fresh seeds was 1.32 mm and the embryo had to grow until it reached at least 2.00 mm to germinate. Embryo growth occurs during warm stratification, after which the radicle emerges when temperatures go down. Seed dormancy was broken in the laboratory at 28/14°C in darkness followed by 15/4°C, but the germination percentage varies depending on the population. In outdoor conditions, seed dispersal occurs in June, the embryo grows during the summer and then the radicle emerges in autumn. The radicle system continues to grow during the winter months, but the shoot does not emerge until the beginning of the spring because it is physiologically dormant and requires a cold period to break dormancy. Early cold temperatures interrupt embryo growth and induce dormancy in seeds with an advanced embryo development. Seeds of N. eugeniae have deep simple epicotyl MPD. In addition, we found that embryo growth and germination were improved by seed storage duration.     

Fatty acid effects on calcium influx and efflux in sarcoplasmic reticulum vesicles from rabbit skeletal muscle

Low concentrations of fatty acids inhibited initial Ca uptake by sarcoplasmic reticulum vesicles, the extent of inhibition varying with chain length and unsaturation in a series of C₁₄–C₂₀ fatty acids. Oleic acid was a more potent inhibitor of initial Ca uptake than stearic acid at 25°C, whereas at 5°C there was less difference between the inhibitory effects of low concentrations of these fatty acids. When the fatty acids were added later, during the phase of spontaneous Ca release that follows Ca uptake in reactions carried out at 25°C, 1–4 μM oleic and stearic acids caused Ca content to increase. This effect was due to marked inhibition of Ca efflux and slight stimulation of Ca influx. At concentrations of >4 μM, both fatty acids inhibited the Ca influx that occurs during spontaneous Ca release; in the case of oleic acid, this inhibition resembled that of initial Ca uptake at 5°C. The different effects of fatty acids at various times during Ca uptake reactions may be explained in part if alterations in the physical state of the membranes occur during the transition from the phase of initial Ca uptake to that of spontaneous Ca release.     

Temperature sensitive phases during the germination of lettuce (Lactuca sativa) seeds

Lettuce seeds cvs Hilde, Feltham King and Avoncrisp were subjected, at different phases during imbibition at 22°C, to a high temperature (33°C) inhibitory for germination, for periods ranging from 4 to 144 h, before returning them to 22°C. The results showed, that the first 4h of imbibition and also the phase between the commencement of mitosis and the onset of radicle emergence were more sensitive to the effects of high temperature than other phases in the germination process. Short exposures (8–24 h) to 33°C commencing at the latter phase delayed germination by up to 4 days, and at the earlier by up to 8 days. Percentage germination was unaffectd except after prolonged exposures (> 48 h) from the beginning of imbibition, which reduced it. Seedling emergence from moist sieved soil was both delayed and reduced when imbibing seeds were exposed for a short period from the beginning of imbibition to 33°C compared with seeds imbibing continuously at 19°C. Germination was delayed and not reduced when seed was exposed to 33°C at the phase between commencement of mitosis and the onset of radicle emergence.     

Factors influencing the storability of Fagus sylvatica L. seeds after release from dormancy

Seeds of beech (Fagus sylvatica L.) that have been subjected to dormancy breaking consisting of 10 weeks of prechilling at 3 °C and 34 % water content (WC) and then desiccation to 10 % WC, are non-dormant (ND). ND seeds are characterised by greater sensitivity to storage conditions, than no prechilled, dormant (D) seeds. The aim of the present work was to investigate factors affecting the loss of seed viability during storage of D and ND beech seeds at different temperatures (4 and 20 °C) and humidity levels (45 and 75 % RH) for 3 weeks. In general, both D and ND seeds maintained a high germination capacity after storage at 4 °C. At 20 °C and 45 and 75 % RH the germination capacity of D seeds diminished to 80 and 28 %, respectively. Under the same conditions, ND seeds lost germination capacity to a greater degree, with only 62 and 7 % germinated seeds, respectively. At 20 °C, an increase in production of reactive oxygen species was observed, and the increase was significantly higher in ND seeds. The loss of germination capacity was coincident with an increase in electrolyte leakage and accumulation of free fatty acids, which suggests that membrane deterioration was the cause of the decline in germinability. ND seeds stored at 20 °C and 45 and 75 % RH showed a greater decrease than D seeds in contents of the primary phospholipids phosphatidylcholine (PC) and phosphatidylethanolamine (PE) as well as in polyunsaturated fatty acids (18:2 and 18:3). ND seeds possessed more unsaturated fatty acids, especially 18:3, than D seeds in the phospholipid fraction before storage. D seeds were characterised by a significantly higher level of α-tocopherol and UV-absorbing phenols. The level of ascorbate was similar in D and ND seeds. D seeds contained glutathione in both reduced (GSH) and oxidised (GSSG) forms, and GSSG dominated GSH. ND seeds contained more GSSG form than D seeds. We concluded that the membranes of ND seeds are exposed to greater oxidative stress during storage due to higher levels of unsaturation and lower levels of α-tocopherol, the main antioxidant that protects membranes against free radical attack.     

Evaluation of different protocols for the analysis of lipophilic plant metabolites by gas chromatography–mass spectrometry using potato as a model

In the analysis of lipophilic plant metabolites by gas chromatography?Cmass spectrometry a step is required to release fatty acids and other analytes from complex molecules. Seven alternative methods were compared to the standard method of 1% H₂SO₄/50°C/16?h using Desirée and Phureja potato tubers as models. With two sodium methoxide alkali-catalysed methods (0.5?M NaOCH₃/50°C/1 and 16?h) recoveries of ferulic acids increased, long chain fatty acids and sterols decreased, 2-hydroxy acids were negligible, solanidine was absent and ??5-avenasterol isomerisation was minimal. Using a harsh alkali hydrolysis (1.0?M KOH/120°C/24?h) followed by a mild methylation (1% H₂SO₄/50°C/1.5?h), recoveries of polyunsaturated fatty acids were poor, sterols decreased but ??5-avenasterol isomerisation was minimal. With a mild alkali hydrolysis (0.5?M NaOH/100°C/5?min) followed by methylation with boron trifluoride (14%BF₃/100°C/30?min) recoveries of sterols and 2-hydroxy fatty acids were similar to the standard method and ??5-avenasterol isomerisation was high. Lower ferulic acid recoveries, absence of solanidine and overestimation of fatty alcohols were evident in both methods involving alkali hydrolysis. Three different methods using hydrochloric acid (1.00?M HCl/70°C/5?h, 0.63?M HCl/110°C/2?h and 2.00?M HCl/50°C/24?h) all gave increased recoveries of 2-hydroxy acids, ferulic acids, solanidine and sterols, although ??5-avenasterol isomerisation increased. Hydrochloric acid methods are recommended for studies requiring quantitative determinations (i.e. concentration of metabolite in sample). Either the hydrochloric acid methods or the standard sulphuric acid method are suggested for determining relative concentrations between samples, although there is a requirement for further studies.     

Oxidation of Fatty Acids by Leishmania braziliensis panamensis1

Heating cultures of Leishmania braziliensis panamensis (grown at 26°C) to 34°C for 1.5–12 h transformed the cells to an ellipsoidally shaped form. The heat treatment caused an increase in the rate of oxidation of both medium and long chain fatty acids but decreased the rate of oxidation of [1-¹⁴C]glucose. The rate of fatty acid oxidation continued to increase for times as long as 20 h after returning the cultures to 26°C. In both the promastigote and heat-induced ellipsoidal forms, the ratio of ¹⁴CO₂ release from [1-¹⁴C]laurate to that from [12-¹⁴C]laurate was generally larger than four, whereas this ratio from [1-¹⁴C]oleate relative to [10-¹⁴C]oleate was approximately two. These data show that metabolic and morphological differentiation begin after a short heat treatment and that some metabolic changes may continue even after the reverse transformation is initiated. The data also suggest that either the ω-terminal portion of the fatty acids is not completely oxidized to acetyl CoA and/or that there are two functional fatty acid oxidation pathways in Leishmania.     

Response of in vitro pollen germination and pollen tube growth of groundnut (Arachis hypogaea L.) genotypes to temperature

Air temperatures of greater than 35 °C are frequently encountered in groundnut‐growing regions, especially in the semi‐arid tropics. Such extreme temperatures are likely to increase in frequency under future predicted climates. High air temperatures result in failure of peg and pod set due to lower pollen viability. The response of pollen germination and pollen tube growth to temperature was quantified in order to identify differences in pollen tolerance to temperature among 21 groundnut genotypes. Plants were grown from sowing to harvest in a poly‐tunnel under an optimum temperature of 28/22 °C (day/night). Pollen was collected at anther dehiscence and was exposed to temperatures from 10° to 47·5 °C at 2·5 °C intervals. The results showed that a modified bilinear model most accurately described the response to temperature of percentage pollen germination and maximum pollen tube length. Genotypes were found to range from most tolerant to most susceptible based on both pollen characters and membrane thermostability. Mean cardinal temperatures (T_min, T_opt and T_max) averaged over 21 genotypes were 14·1, 30·1 and 43·0 °C for percentage pollen germination and 14·6, 34·4 and 43·4 °C for maximum pollen tube length. The genotypes 55‐437, ICG 1236, TMV 2 and ICGS 11 can be grouped as tolerant to high temperature and genotypes Kadiri 3, ICGV 92116 and ICGV 92118 as susceptible genotypes, based on the cardinal temperatures. The principal component analysis identified maximum percentage pollen germination and pollen tube length of the genotypes, and T_max for the two processes as the most important pollen parameters in describing a genotypic tolerance to high temperature. The T_min and T_opt for pollen germination and tube growth, rate of pollen tube growth were less predictive in discriminating genotypes for high temperature tolerance. Genotypic differences in heat tolerance‐based on pollen response were poorly related (R² = 0·334, P = 0·006) to relative injury as determined by membrane thermostability.     

Improvement of polyunsaturated fatty acids synthesis by the coexpression of CYB5 with desaturase genes in Saccharomyces cerevisiae

Since Saccharomyces cerevisiae contains Δ9 fatty acid desaturase (OLE1) as a sole fatty acid desaturase, it produces saturated and monounsaturated fatty acids of 16- and 18-carbon compounds. We showed earlier that Kluyveromyces lactis Δ12 (KlFAD2) and ω3 (KlFAD3) fatty acid desaturase genes enabled S. cerevisiae to make also polyunsaturated fatty acids (PUFAs), linoleic (18:2n-6), and α-linolenic (18:3n-3) acids. Unlike Δ9 fatty acid desaturase Ole1p, the two added fatty acid desaturases (KlFAD2and KlFAD3) do not contain a cytochrome b5 domain, and we now report on effects of the overexpression of K. lactis and S. cerevisiae cytochrome b5 (CYB5) genes as well as temperature effects on PUFA synthesis. Without extra cytochrome b5, while PUFA synthesis is significant at low temperature (20 °C), it was marginal at 30 °C. Overexpression of cytochrome b5 at 20 °C did not affect the fatty acid synthesis so much, but it significantly enhanced the synthesis of PUFA at 30 °C.     

Morphophysiological dormancy in seeds of the ANA grade angiosperm Schisandra arisanensis (Schisandraceae)

We determined the kind of seed dormancy in Schisandra arisanensis, an ANA grade ([A]mborellales [N]ymphaeales [A]ustrobaileyales) angiosperm with medicinal value. Seeds have small underdeveloped embryos, and following seed maturity their length increased approximately 360% before radicle emergence. Germination was delayed 6–8 weeks, and the percentage and rate were much higher at 15/6, 20/10 and 25/15°C than at 30/20°C. For seeds incubated at 5/5°C (8 weeks) → 15/6°C (4 weeks) → 20/10°C (8 weeks) → 25/15°C (12 weeks) → 20/10°C (5 weeks), embryos grew at 15/6°C → 20/10°C, and almost all seeds that germinated (89%) did so at 20/10°C → 25/15°C. When seeds were incubated in a complementary temperature sequence, 25/15°C (12 weeks) → 20/10°C (8 weeks) → 15/6°C (4 weeks) → 5/5°C (9 weeks) → 15/6°C (4 weeks), embryos grew at 25/15°C → 20/10°C. Nearly all seeds that germinated (93%) did so at 25/15°C → 20/10°C and at 15/6°C following 9 weeks at 5/5°C. Based on the temperature requirements for embryo growth and seed germination, seeds of this species have non‐deep simple morphophysiological dormancy (C_1bB).     

Ecophysiology of embryo development and seed germination of the European woodland herbaceous perennial Corydalis cava (L.) Schweigg. & Körte subsp. cava (Fumariaceae)

In this study we examined the germination ecology with special reference to the temperature requirements for embryo development and germination of Corydalis cava subsp. cava, under both outdoor and laboratory conditions. Corydalis cava is a spring flowering woodland tuberous geophyte widely distributed across Europe. Germination phenology, including embryo development and radicle and cotyledon emergence, was investigated in a population growing in northern Italy. Immediately after harvest, seeds of C. cava were sown both in the laboratory under simulated seasonal temperatures and naturally. Embryos, undifferentiated at the time of seed dispersal, grew during summer and autumn conditions, culminating in radicle emergence in winter, when temperatures fell to ca 5°C. Cotyledon emergence also occurred at ca 5°C, but first emergence was delayed until late winter and early spring. Laboratory experiments showed that high (summer) followed by medium (autumn) and low temperatures (winter) are needed for physiological dormancy loss, embryo development and germination respectively. Unlike seeds of C. cava that germinated in winter, in other Corydalis species radicle emergence occurred in autumn (C. flavula) or did not depend on a period of high summer temperature to break dormancy (C. solida). Our results suggest that subtle differences in dormancy and germination behavior between Corydalis species could be related to differences in their geographical distribution.     

Differentiation of the Soft-Rotting Erwinias (the Carotovora Group) by Fatty Acid Composition

About 90 % of total cellular fatty acids in E. carotovora, grown on KB medium for 1 day at 28°C, were the saturated, even-carbon straight chains 12 : 0 (5.9%), 14 : 0 (1.7%) and 16 : 0 (30.1 %), and the unsaturated 16 : 1 (36.6%) and 18 : 1 (15.0%) fatty acids. Other components were the hydroxy-substituted 3-OH 14 : 0 (5.3%) and 21 minor fatty acids each occurring less than 0.1 % of the total — 14 of them reported herein for the first time in Erwinia. The ratio of 16 : 1/18 : 1 in KB-grown cells was as useful in differentiating subspecies of E. carotovora as previously reported by other workers for TSA-grown cells. A comparison of fatty acid profiles of E. carotovora on 4 different media, KB, TSA, NA and PDA, indicated that on KB there was the greatest proportion of Class A and C fatty acids, and the highest number of detectable components. Significant differences were noted in the 5 major fatty acids and in cyclic fatty acids among the 4 species of the carotovora group –E. carotovora, E. chrysanthemi, E. rhapontici and E. cypripedii. These differences could be expressed as algorithms that, when used in sequential dichotomous steps, could differentiate the 4 species.     

Seed germination time course and seedling development of Clintonia udensis Trautv. et Mey. (Uvulariaceae): a typical cool temperate woodland perennial in Japan

Seed germination time course and seedling development mechanisms of Clintonia udensis Trautv. et Mey. (Uvulariaceae) were investigated under experimental condition. Seed germination tests were carried out under four thermal regimes, i. e. 10, 15, 20, and 25°C, after seeds were harvested, and stored at 5°C in wet conditions for 6 months under light‐exposed or shaded conditions. Approximately 63% of all seeds produced had the potential to germinate beyond 4 years and 6 months. The developmental process after germination continued for over 2 years. Phase I: the radicle first breaks through the seed coat 2 years after fructification. Phase II: the radicle becomes much larger with a hypocotyle. Phase III: part of the cotyledon elongates over 20 mm. Phase IV: the plumule further develops in two steps, i. e. the plumule is first formed, while cotyledon is disappearing, and then the plumule appears with second and third radicles, growing with cotyledon.     

Impact of membrane fatty acid composition on the uncoupling sensitivity of the energy conservation of Comamonas testosteroni ATCC 17454

The fatty acid composition of pyruvate-grown Comamonas testosteroni ATCC 17454 was analyzed after growth at 30 and 20°C and after half-maximum growth inhibition caused by different membrane-active chemicals at 30°C. Palmitic acid (16:0), palmitoleic acid (16:1 ω7c) and vaccenic acid (18:1 ω7c) were the dominant fatty acids. At 20°C, the proportion of palmitic acid decreased and those of palmitoleic and vaccenic acid increased. Saturation degree was also lowered when half-maximum growth inhibition was caused by 4-chlorosalicylic acid, 2,4-dichlorophenoxyacetic acid and 2,4-dinitrophenol and, to a lesser extent, in the presence of 2,4-dichlorophenol, phenol and ethanol. It appeared that the dissociated forms of the former group of chemicals were preferentially incorporated near the head group region of the lipid bilayer, thereby somewhat extending the outer region of the membranes, and that the increased amount of bent, unsaturated fatty acids helped to maintain membrane integrity. Irrespective of how the decrease of the saturation degree was triggered, it caused electron transport phosphorylation (adenosine triphosphate synthesis driven by n-hexanol oxidation) to become more sensitive to uncoupling. Apparently, the viscosity and phase stability of the cytoplasmic membrane of C. testosteroni were maintained at the price of a reduced protection against energy toxicity.     

Fungal infection dynamics in response to temperature in the lepidopteran insect Galleria mellonella

This study examines how the dynamics of fungus–insect interactions can be modulated by temperature. The wax moth, Galleria mellonella, is a well‐studied and important model insect whose larvae in the wild develop optimally at around 34 °C in beehives. However, surprisingly little research on wax moths has been conducted at relevant temperatures. In this study, the entomopathogenic fungus Metarhizium robertsii inflicted rapid and substantial mortality on wax moth larvae maintained at a constant temperature of 24 °C, but at 34 °C a 10 fold higher dose was required to achieve an equivalent mortality. The cooler temperature favored fungal pathogenicity, with condial adhesion to the cuticle, germination and hemocoel invasion all significantly enhanced at 24 °C, compared with 34 °C. The wax moth larvae immune responses altered with the temperature, and with the infective dose of the fungus. Enzyme‐based immune defenses (lysozyme and phenoloxidase) exhibited enhanced activity at the warmer temperature. A dramatic upregulation in the basal expression of galiomicin and gallerimycin was triggered by cooling, and this was augmented in the presence of the fungus. Profiling of the predominant insect epicuticular fatty acids revealed a 4–7 fold increase in palmetic, oleic and linoleic acids in larvae maintained at 24 °C compared with those at 34 °C, but these failed to exert fungistatic effects on topically applied fungus. This study demonstrates the importance of choosing environmental conditions relevant to the habitat of the insect host when determining the dynamics and outcome of insect/fungus interactions, and has particular significance for the application of entomopathogens as biocontrol agents.     

Inhibition of methanogenesis and its reversal during biogas formation from cattle manure

The composition of volatile fatty acids in the biogas digester based on cattle manure as substrate and stabilised at 25°C showed that it contained 87–88% branched chain fatty acids, comprising of isobutyric and isovaleric acids, in comparison to 38 % observed in the digester operating at 35°C. Mixed cellulolytic cultures equilibrated at 25°C (C-25) and 35‡C (C-35) showed similar properties, but rates of hydrolysis were three times higher than that observed in a standard biogas digester. The proportion of isobutyric and isovaleric were drastically reduced when C-25 was grown with glucose or filter paper as substrates. The volatile fatty acids recovered from C-25 (at 25°C) inhibited growth of methanogens on acetate, whereas that from C-35 was not inhibitory. The inhibitory effects were due to the branched chain fatty acids and were observed with isobutyric acid at concentrations as low as 50 ppm. Addition of another micro-organismRhodotorula selected for growth on isobutyric completely reversed this inhibition. Results indicate that the aceticlastic methanogens are very sensitive to inhibition by branched chain fatty acids and reduction in methane formation in biogas digester at lower temperature may be due to this effect.     

哈氏弧菌脂酰-ACP合成酶的体外功能

【目的】系统鉴定哈氏弧菌脂酰-ACP合成酶(Acyl-ACP synthetase,Aas S)以不同链长游离脂肪酸和非脂肪链羧酸作为底物的体外催化反应。【方法】利用非变性蛋白质凝胶电泳和紫外分光光度计法从定性和定量两个方面分析了Aas S的体外催化功能与活性。【结果】Aas S能够催化不同链长直链的自由脂肪酸合成脂酰-ACP,其中以C6–C12作为底物时活性最高;以羟基脂肪酸作为底物的情况下,Aas S催化C8–C14的羟基脂肪酸有较高的活性。非脂肪链羧酸类作为底物的反应中,20种蛋白质氨基酸、苯甲酸和水杨酸均可以作为Aas S的底物,合成相应的脂酰-ACP。【结论】本研究系统地证明了哈氏弧菌脂酰-ACP合成酶(Aas S)对不同底物的不同催化活性,为生物体内氨基酸代谢和菌黄素合成代谢的研究提供了可行性的分析依据。     

The effect of low temperature on fatty acid composition and tocopherols of the red microalga, <Emphasis Type="Italic">Porphyridium cruentum</Emphasis>

Porphyridium cruentum was grown in 10 L batch culture at 18°C, pH 8.0 and 28‰ salinity. The cells were harvested in the stationary phase and the fatty acid composition analysed by GC and tocopherol content by HPLC. A total of 14 fatty acids were identified including saturated fatty acids (13:0, 14:0, 14:0 iso, 15:0, 16:0, 16:0iso) and monounsaturated fatty acids (MUFAs; 16:1(n-7), 18:1(n-7), 18:1(n-9). Polyunsaturated fatty acids (PUFAs) were the predominant fatty acids detected, reaching 43.7% of total fatty acids in the stationary phase of culture. Among the PUFAs, eicosapentaenoic acid (EPA, 20:5(n-3)) was dominant (25.4%), followed by 12.8% arachidonic acid (AA, 20:4(n-6)). α-Tocopherol and γ-tocopherol contents were 55.2 μg g⁻¹ dry weight and 51.3 μg g⁻¹ dry weight respectively.