Effect of C/N ratio and aeration on the fatty acid composition of heterotrophicChlorella sorokiniana

The effect of the carbon to nitrogen (C/N) ratio of the medium and the aeration rate on the lipid content and fatty acid composition ofChlorella sorokiniana was investigated using heterotrophic, batch culture. Both parameters had a significant effect. A C/N ratio of approximately 20, was found to indicate a change from carbon to nitrogen limitation forC. sorokiniana. Cell lipid content was at a minimum at this value and increased at both higher and lower C/N values. Low C/N ratios favoured a high proportion of trienoic fatty acids at the expense of monoenoic acids. Aeration enhanced cell growth, fatty acid yield and the synthesis of unsaturated dienoic and trienoic fatty acids, but reduced cell lipid content. The results demonstrate that the fatty acid composition and lipid content of heterotrophically-grown microalgae can be favourably manipulated by varying culture conditions.     

Rhizosphere microorganism effects on soluble amino acids,sugars and organic acids in the root zone ofAgropyron cristatum,A. smithii andBouteloua gracilis

Three axenic and rhizosphere microorganism-inoculated shortgrass steppe plant species were evaluated for possible differences in residual organic carbon and nitrogen present as sugars, organic acids and amino acids. IntroducedAgropyron cristatum was compared toA. smithii andBouteloua gracilis, which are dominant species in the native shortgrass steppe. These plants, grown for 90 days in root growth chambers, showed differences in residual organic carbon and nitrogen per gram of root, and rhizosphere microbe presence resulted in additional changes in these compounds. The root biomass ofB. gracilis was significantly increased with microbes present. TheAgropyron species had significantly lower amino acid levels with microbes present, while under the same conditions, theB. gracilis showed significant decreases in residual sugars. Based on the amino acids, sugars and organic acids, the C/N ratio of the sterileA. cristatum was higher than forB. gracilis. Rhizosphere microbe presence did not result in changes in these C/N ratios. These results suggest thatA. cristatum, with microbes present, will have lower levels of amino acids present, whileB. gracilis, with a lower C/N ratio, will have sugars used to a greater extent by the rhizosphere microbes. This resulted in the higher levels of residual soluble organic C and N in the rhizosphere ofB. gracilis, in comparison with the introducedA. cristatum. These differences may be critical in influencing the course of nutrient accumulation and plant competition in short-grass steppe communities, and in understanding basic aspects of plant-rhizosphere microorganism interactions.     

Diet-induced variations in fatty acid content and composition of two on-grown stages of Artemia Salina

Three species of microalgae, the freshwater Euglena gracilis and themarine Dunaliella salina and Tetraselmis suecica, were fed tothe brine shrimp Artemia salina in order to compare their suitabilityin terms of fatty acid enrichment, and their effect on the biometric parametersof the zooplankter. The fatty acid content and composition were analyzed for the post-larval and pre-adult stages of Artemia fed the algae and theresults compared to the initial content of unfed 24-hour post-hatch nauplii.Differences in the total fatty acid content occurred between the three stages,the fatty acid profile being determined by the composition of the diet. A decreasing trend for almost all the individual fatty acids occurred throughdevelopment from post-larva to pre-adult with each of the three algal diets.Biometrical differences between Artemia fed the marine algae and that fed Euglena were not consistent in the post-larval stage, but became considerable in the pre-adult stage. Artemia fed with Euglena achieved twice the weight of animals fed the marine algae and showed thehighest length. The implications for the use of on-grown Artemia as afeed in larviculture of marine and freshwater fish and crustaceans are considered.     

Effect of eight benthic diatoms as feed on the growth of red abalone (Haliotis rufescens) postlarvae

The growth rate of abalone post larvae of Haliotis rufescens fed ad libitum with a benthic monoalgal diatom culture maintained as monocultures on a semi-commercial scale, was evaluated and correlated with the biochemical composition of the diatoms. The cell size (7.0 × 4.0 μm to 21.0 × 7.5 μm), protein percentage (7.42% to 13.66%), and ash content (49.03% to 59.61%) were different among diatom strains; lipid percentage, nitrogen free extract, and energy content (Kcal g⁻¹) were similar among diatom strains. The values of essential and non-essential amino and fatty acids composition differed among diatom strains. Differences in the abalone shell length and orthogonal analyses revealed postlarval growth was dependent on the quality of the food source. Postlarvae abalone displaying the longest shell lengths were fed Nitzschia thermalis var. minor and Amphiprora paludosa var. hyalina (1,712.0 ± 61 μm and 1,709 ± 67 μm, respectively), followed by Navicula incerta (1,413.3 ± 43 μm). The fatty acid content of benthic diatoms and abalone growth rate were not correlated.     

Inverse relationship between carotenoid and lipid formation in Rhodotorula gracilis according to the C/N ratio of the growth medium

Production of carotenoid by Rhodotorula gracilis was highest at 26 mg/g dry weight with a carbon/nitrogen (C/N) ratio in the medium of 10:1. This was 15 times higher than when the C/N ratio was 160:1. With this high C/N ratio, the yeast produced up to 55% lipid compared only 20% lipid with the low C/N ratio. Both carotenoid and lipid production were non-growth associated.     

A comparison of the major lipid classes and fatty acid composition of marine unicellular cyanobacteria with freshwater species

The fatty acid composition of two motile (strains WH 8113 and WH 8103) and one nonmotile (strain WH 7803) marine cyanobacteria has been determined and compared with two freshwater unicellular Synechocystis species (strain PCC 6308 and PCC 6803). The fatty acid composition of lipid extracts of isolated membranes from Synechocystis PCC 6803 was found to be identical to that of whole cells. All the marine strains contained myristic acid (14:0) as the major fatty acid, with only traces of polyunsaturated fatty acids. This composition is similar to Synechocystis PCC 6308. The major lipid classes of the nonmotile marine strain were identified as digalactosyl diacylglycerol, monogalactosyl diacylglycerol, phosphatidylglycerol, and sulfoquinovosyl diacylglycerol, identical to those found in other cyanobacteria.Abbreviations DGDG Digalactosyl diacylglycerol - MGDG Monogalactosyldiacylglycerol - PG Phosphatidylglycerol - SGDG sulfoquinovosyl diacylglycerol - gc gas chromatography - ms mass spectrometry     

Surface properties and intracellular speciation revealed an original adaptive mechanism to arsenic in the acid mine drainage bio-indicator Euglena mutabilis

Euglena mutabilis is a protist ubiquitously found in extreme environments such as acid mine drainages which are often rich in arsenic. The response of E. mutabilis to this metalloid was compared to that of Euglena gracilis, a protist not found in such environments. Membrane fatty acid composition, cell surface properties, arsenic accumulation kinetics, and intracellular arsenic speciation were determined. The results revealed a modification in fatty acid composition leading to an increased membrane fluidity in both Euglena species under sublethal arsenic concentrations exposure. This increased membrane fluidity correlated to an induced gliding motility observed in E. mutabilis in the presence of this metalloid but did not affect the flagellar dependent motility of E. gracilis. Moreover, when compared to E. gracilis, E. mutabilis showed highly hydrophobic cell surface properties and a higher tolerance to water-soluble arsenical compounds but not to hydrophobic ones. Finally, E. mutabilis showed a lower accumulation of total arsenic in the intracellular compartment and an absence of arsenic methylated species in contrast to E. gracilis. Taken together, our results revealed the existence of a specific arsenical response of E. mutabilis that may play a role in its hypertolerance to this toxic metalloid.     

Content of arachidonic and eicosapentaenoic acids in polar lipids from Gracilaria (Gracilariales,Rhodophyta)

Fatty acid composition, especially the distribution of eicosapolyenoic acids in several species of Gracilaria, was analyzed in relation to their taxonomy. The species have been grouped into two types based on distribution of these polyenoic acids: Type 1, which contains palmitic, oleic and arachidonic acids as the major components, and Type II, which contains eicosapentaenoic acid in addition to Type I fatty acids. Octadecapolyenoic acids were detected only in trace amounts in each Type. A similar remarkable difference also was observed in the fatty acid composition of lipid classes. The major component of eicosapolyenoic acids in Type I was arachidonic acid in all lipid classes. In Type II, eicosapentaenoic acid was the major component in monogalactosyl diacylglycerol, digalactosyl diacylglycerol, sulfoquinovosyl diacylglycerol and phosphatidylglycerol. Arachidonic and eicosapentaenoic acids were contained in large amounts in Type II phosphatidylcholine. Grouping of Gracilaria species into Type I and Type II is not entirely consistent with morphological and taxonomic features, but the difference in fatty acid composition is likely due to genetic rather than to environmental factors.     

The effect of rapamycin on biodiesel-producing protist Euglena gracilis

Rapamycin induces autophagy with lipid remodeling in yeast and mammalian cells. To investigate the lipid biosynthesis of Euglena gracilis, rapamycin was supplemented in comparison with two model algae, Chlamydomonas reinhardtii and Cyanidioschyzon merolae. In Euglena, rapamycin induced the reduction of chlorophylls and the accumulation of neutral lipids without deterring its cell proliferation. Its lipidomic profile revealed that the fatty acid composition did not alter by supplementing rapamycin. In Chlamydomonas, however, rapamycin induced serious growth inhibition as reported elsewhere. With a lower concentration of rapamycin, the alga accumulated neutral lipids without reducing chlorophylls. In Cyanidioschyzon, rapamycin did not increase neutral lipids but reduced its chlorophyll content. We also tested fatty acid elongase inhibitors such as pyroxasulfone or flufenacet in Euglena with no significant change in its neutral lipid contents. In summary, controlled supplementation of rapamycin can increase the yield of neutral lipids while the scheme is not always applicable for other algal species.     

Lipid content and fatty acid composition in hypogeous organs ofHelleborus species (Ranunculaceae)

Root and rhizome of fourHelleborus species:H. viridis, H. odorus, H. niger, H. foetidus were examined throughout a two-year period in order to determine the variation of lipid content and fatty acid composition during the ontogenetic cycle. In the deciduous geophytesH. viridis andH. odorus subsp.laxus the lipid content reaches its maximum during the quiescent phase, whereas in the evergreen geophyteH. niger the lipid content is highest during the main growth period. In the chamaephyteH. foetidus lipid content is always very low and it does not show variation throughout the year. In all species the fatty acids detected in the neutral fraction are myristic, palmitic, stearic, oleic and linoleic acid. Palmitic and linoleic acid are always present in larger quantities. The pattern of the relative content of saturated/unsaturated fatty acids seems to be linked to the life form of these species.     

Lipid quality of the diatoms Skeletonema costatum and Navicula gregaria from the South Atlantic Coast (Argentina): evaluation of its suitability as biodiesel feedstock

Since the fatty acid ester profile of a given biofuel is relatively consistent with the source’s fatty acid profile, the properties of the biodiesel produced from a particular feedstock exhibit predictable quality. Thus, lipid fractions and the fatty acid composition of stationary growth-phase cultures of the local strains of the diatoms Skeletonema costatum and Navicula gregaria were analysed to evaluate their suitability as biodiesel feedstock. Total lipid content was 20.83 pg cell⁻¹ in S. costatum and 19.17 pg cell⁻¹ in N. gregaria. Neutral lipids were the main fraction of total lipids in both species, accounting for ca. 65% and 76%, respectively. S. costatum was predominant in saturated fatty acids (SFAs; 43.48 %) and monounsaturated fatty acids (MUFAs; 40.11%), while N. gregaria was predominant in MUFAs (54.85%), followed by SFAs (33.42%). In S. costatum, the main fatty acids in neutral lipid fraction were myristic, palmitic, palmitoleic and oleic acids, while the main ones in N. gregaria were palmitic and palmitoleic acids. The oils extracted from these species presented linolenic acid contents within biodiesel’s quality specifications. However, in neutral lipid fraction both species showed eicosapentaenoic acid levels higher than the required limit. The lipid quality analysed in both species suggests that a biodiesel derived from these oils may present an acceptable cetane number, but likely poor cold-flow properties. This baseline information is useful for future research tending to find more suitable conditions in order to improve oil yield. In addition, both estuarine species neither compete with agriculture for food nor require farmland nor fresh water.     

Triacylglycerols in the seeds of northern Scots pine,Pinus sylvestris L., and Norway spruce,Picea abies (L.) Karst.

The geographical variation in the composition of triacylglycerols in seeds of Scots pine (Pinus sylvestris L.) and Norway spruce [Picea abies (L.) Karst.], grown in Finland, was analyzed. The total lipid content of pine seeds was slightly higher in the northernmost provenance (68 °50N), whereas the lipid content of spruce seeds was not affected systematically by the geographical origin of the seeds. The species studied differed in the proportions of fatty acids in their triacylglycerols, though the three most abundant components were the same, i.e. oleic acid (181 n9), linoleic acid (182n-6) and 5,9,12-octadecatrienoic acid (183 5c9c12c). These fatty acids corresponded to more than 80 mol% of the total fatty acids. According to mass spectrometric analyses, the triacylglycerols of both spruce and pine seeds consisted of the same molecular species with 52–56 acyl carbons, but in different proportions. Molecules with 54 acyl carbons represented approximately 75% of the pine and 85% of the spruce triacylglycerols, with the most abundant molecular species being 545, 546 and 547. Some minor differences in the fatty acid composition of triacylglycerols of pine seeds from different seed collecting areas were found: the proportion of linoleic acid slightly increased whereas that of 5,11,14-eicosatrienoic acid decreased towards the northern origins. Similar differences were not found in the proportions of fatty acids in spruce seed lots. Furthermore, the proportions of triacylglycerols in both pine and spruce seeds from northern and southern collecting areas were not significantly different. The higher content of total lipids in spruce seeds compared with pine seeds may be due to the structure of the seed coat, and the lipophilic layers inside it, acting as a barrier to imbibition.     

Dr Han L. Golterman,a Limnologist: a tribute on the occasion of his 65th birthday and retirement

The green algae D. tertiolecta, the flagellate I. galbana and the diatom C. gracilis were grown in batch cultures. The organisms were analysed for lipid class composition at the logarithmic and stationary growth phases using the Chromarod-Iatroscan thin layer chromatography with flame ionization detection (TLC-FID) system.There were major differences in lipid class production among the organisms investigated, but few differences in lipid class distribution between log phase and stationary phase cultures of D. tertiolecta and I. galbana. C. gracilis displayed the general trend exhibited in diatom metabolism, which can be characterized by an increase in triacylglycerol synthesis in situations of stress.     

Lipid Accumulation during Canola Seed Germination in Response to Cinnamic Acid Derivatives

The objective of this research was to investigate how ferulic and p-coumaric acids affect lipid and fatty acid composition during canola (Brassica napus L.) seed germination. Data showed that both compounds increased total lipid and fatty acid contents in the cotyledons during germination. The largest accumulation in lipids occurred at 1.0 mM p-coumaric acid with an increase in all unsaturated fatty acids. The results suggest that allelochemicals interfere in canola seed germination by reducing lipid mobilization.     

Organic aggregates formed by benthopleustophyte brown alga Acinetospora crinita (Acinetosporaceae,Ectocarpales)

This work presents the elemental, polysaccharide, and fatty acid compositions of benthic aggregates formed by the filamentous brown alga Acinetospora crinita, which are widely spread on the rocky bottoms of the Mediterranean Sea. The aggregates can be characterized as mineralized centers in which regeneration of nutrients and recycling of dissolved organic matter actively occur and favor the development of an abundant phytoplankton community. Analyses of the stable isotopes of C and N display their marine origin and could provide evidence of the processes that occur inside/outside of the aggregates. The monosaccharide compositions of Adriatic and Tyrrhenian mucilages produced by brown alga A. crinita were quite similar. In particular, the Adriatic sample compositions resembled the average composition of the Tyrrhenian high molecular weight exopolymers, and the observed differences could be ascribed to different degradation stages. The fatty acid patterns found for the aggregates were similar to those observed in the isolated A. crinita algae with variable contributions from embedded diatom species. The bacterial contribution to the fatty acid pool was quite low, most likely due to the known poor conditions for their heterotrophic growth.     

Lipid contents of five species of notothenioid fish from high-Antarctic waters and ecological implications

Comprehensive data are presented on the total lipid contents of five species of notothenioid fish collected during summer 1991 in the Weddell Sea and the Lazarev Sea south of 69°S. The species were selected based on their different modes of life, benthic, benthopelagic and pelagic, to examine how the life style — among other factors — affects the proximate composition of these high-Antarctic fishes. Lipid contents of whole specimens showed an extremely wide range from 3.1 to 67.5% of dry weight (%DW), with corresponding carbon/nitrogen (C/N) ratios between 3.4 and 11.3. Lowest lipid contents were found in the benthic species Bathydraco marri and Dolloidraco longedorsalis with means of 11.0 and 11.9 %DW. The benthopelagic Trematomus lepidorhinus had an intermediate mean lipid content of 20.8 %DW, and the pelagic species Pleuragramma antarcticum and Aethotaxis mitopteryx were richest in lipid with means of 47.0 %DW and 60.8 %DW. There was a pronounced ontogenetic lipid accumulation with increasing size discernible in the lipid-rich species, especially in P. antarcticum. No clear relationship was found between lipid content and sex or maturity in A. mitopteryx and T. lepidorhinus, only the males of B. marri had higher lipid contents than the females. Lipid contents and water contents were inversely correlated. In conclusion, the mode of life of these species was clearly reflected by their lipid contents and lipids seem to have an important function, particularly as buoyancy aids in the pelagic species, which like all notothenioids lack a swim-bladder.     

Distribution of alkanes and fatty acids in theCondalia montana (Rhamnaceae) species complex

The alkane and fatty acid composition of the lipid extracts from leaves of 14 populations ofCondalia: C. microphylla f.xanthocarpa, C. microphylla f.erythrocarpa, C. microphylla f.melanocarpa, C. montana, andC. buxifolia, were determined by gas chromatography. Seventeen alkanes and 14 fatty acids were investigated and a predominance of nonacosane, hentriacontane, palmitic and linoleic acids in all species was found.     

Lipid composition of halophilic species of Dunaliella from the dead sea

The lipid patterns of six halophilic Dunaliella species from the Dead Sea (C₉, D_11a, D_11b, D₁₃, F_20a and D. viridis) were found to be generally similar to those of halotolerant Dunaliella species previously examined, except for the presence in the halphilic Dunaliella of small to trace amounts of one or more (up to five) unidentified glycolipids. The lipids of two of the halophilic algae, species C₉ and D_11b, were studied in detail and were found to be similar in composition. Glycolipids were the major group (55.0 and 53.2 mol % for C₉ and D_11b, respectively), followed by neutral lipids (mainly triacyglycerols: 21.3 mol %; 24.6 mol %), whereas phospholipids were a much smaller fraction (6.5 mol %; 5.8 mol %). Monogalactosyldiacylglycerol was the largest component (22.0 mol %; 24.3 mol %) but digalactosyldiacylglycerol (18.7 mol %; 14.9 mol %) and sulfoquinovosyldiacylglycerol (14.3 mol %; 14.0 mol %) were also present in high concentrations. All phospholipids were present at low concentrations: phosphatidylglycerol (4.4 mol %; 3.1 mol %); phosphatidylethanolamine (1.1 mol %; 0.7 mol %); phosphatidylcholine (0.9 mol %; 1.9 mol %); and phosphatidylinositol (traces). Diacylglyceryl-O-(N,N,N-trimethyl)homoserine was present in C₉ and D_11b (3.3 mol %; 9.3 mol %) and in all the other species examined. Fatty acid composition of the individual lipid components of C₉ and D_11b showed characteristic differences between glycolipids and phospholipids, in a similar pattern for both algae. The major fatty acids detected in all species examined were -linolenic, linoleic, palmitic, oleic and a polyunsaturated sixteen carbon acid.     

Composition of lipids, fatty acids and sterols in Okinawan corals

A survey of lipid composition was made for 15 cnidarians from Okinawa, Japan. Eleven zooxanthellate scleractinian corals, an azooxanthellate scleractinian coral Tubastrea sp., a soft coral Lobophytum crassum, a hydroid coral Millepora murrayi and a sea anemone Boloceroides sp. were examined to elucidate the total lipid content, fatty acid composition for each lipid class and sterol composition. All specimens contained monoalkyldiacylglycerol which migrated between the triacylglycerols and esters on thin layer chromatography (TLC). Analysis by high performance thin layer chromatography (HPTLC) and Gas chromatography-mass spectrometry (GC-MS) revealed that these cnidarians were rich in wax ester and triacylglycerol, and that palmitic acid (16:0) was the most abundant fatty acid component of these lipid classes, followed by stearic (18:0) and oleic (18:1, n-9) acid in order of concentration. Of 11 sterols separated, four sterols were identified. It is suggested that sterol composition may be more useful for the biochemical classification of these cnidarians than fatty acid composition.     

Identification of the alga known as <Emphasis Type="Italic">Nannochloropsis</Emphasis> Z-1 isolated from a prawn farm in Hainan,China as <Emphasis Type="Italic">Chlorella</Emphasis>

An alga known as “Nannochloropsis”, isolated from a prawn farm in Hainan, China, has been critically investigated and identified as Chlorella, a member of the Chlorophyceae based on fatty acid composition, ultrastructure, and 18S rDNA. Cells of this alga were spherical, measured by 1–6 μm in diameter and were enclosed in thin walls of approximately 0.04 μm thickness. They contained several small mitochondria, two to three thylakoids and had no vacuoles. There were many pyrenoids in the algal cells and their thylakoid lamellae were sparse and not translucent. Many lipid droplets were present in the cytoplasm. The total lipid content of this alga was 3% per gram dry weight and its major fatty acids were C_16:0, C_18:0, C_18:1, C_18:2, C_18:3 and C_20:0. Eicosapentaenoic acid (C_20:5, EPA) was not detected. The length of its 18S rDNA sequence was 1,712 bp. 18S rDNA sequence analyses indicated that this alga was a species of Chlorella.