Total lipid and fatty acid composition of eight strains of marine diatoms

Fatty acid composition and total lipid content of 8 strains of marine diatoms (Nitzschia frustrula, Nitzschia closterium, Nitzschia incerta, Navicula pelliculosa, Phaeodactylum tricornutum, Synedra fragilaroides) were examined. The microalgae were grown under defined conditions and harvested at the late exponential phase. The major fatty acids in most strains were 14∶0 (1.0%–6.3%), 16∶0 (13.5–26.4%), 16∶1n−7 (21.1%–46.3%) and 20∶5n−3 (6.5%–19.5%). The polyunsaturated fatty acids 16∶2n−4, 16∶3n−4, 16∶4n−1 and 20∶4n−6 also comprised a significant proportion of the total fatty acids in some strains. The characteristic fatty acid composition of diatoms is readily distinguishable from those of other microalgal groups. Significant concentration of the polyunsaturated fatty acid 20∶5n−3 (eicosapentaenoic acid) was present in each strain, with the highest proportion in B222 (19.5%). Project supported by the Hi-Tech “863” Programs of the China Ministry of Science and Technology (863-819-02-01).     

Comparative fatty acid composition of fourSargassum species (Fucales,Phaeophyta)

Fatty acid composition of fourSargassum species from Qingdao and Shidao, Shandong Province was investigated. 16:0 (palmitic acid) was the major saturated fatty acid. C₁₈ and C₂₀ were the main polyunsaturated fatty acids (PUFAs). Arachidonic acid and eicosapentaenoic acid predominated among polyenoic acids in all the algal species examined, except forSargassum sp. which had low concentration of eicosapentaenoic acid. Contribution No. 2354 from the Institute of Oceanology, Chinese Academy of Sciences     

Analysis of fatty acid composition of sea cucumber Apostichopus japonicus using multivariate statistics

Fatty acids （FAs） provide energy and also can be used to trace trophic relationships among organisms. Sea cucumber Apostichopus japonicus goes into a state of aestivation during warm summer months. We examined fatty acid profiles in aestivated and non-aestivated A. japonicus using multivariate analyses （PERMANOVA, MDS, ANOSIM, and SIMPER）. The results indicate that the fatty acid profiles of aestivated and non-aestivated sea cucumbers differed significantly. The FAs that were produced by bacteria and brown kelp contributed the most to the differences in the fatty acid composition of aestivated and non- aestivated sea cucumbers. Aestivated sea cucumbers may synthesize FAs from heterotrophic bacteria during early aestivation, and long chain FAs such as eicosapentaenoic （EPA） and docosahexaenoic acid （DHA） that produced from intestinal degradation, are digested during deep aestivation. Specific changes in the fatty acid composition of A. japonicus during aestivation needs more detailed study in the future.     

EFFECT OF LIGHT INTENSITY ON THE TOTAL LIPID AND FATTY ACID COMPOSITION OF SIX STRAINS OF MARINE DIATOMS

The effect of light intensity ( 1500 Ix and 5000 Ix) on the total lipid and fatty acid composition of six strains of marine diatoms Cylindrotheca fusiformis (B211 ), Phaeodactylum tricornutum (Bl14, Bl18 and B221) Nitzschia closterium (B222) and Chaetoceros gracilis (B13) was investigated.The total lipids of B13, Bl14, and B211 grown at 5000 Ix were lower than those grown at 1500 Ix. No evident changes were observed in Bl18, B221 and B222. Fatty acid composition changed considerably at different light intensity although no consistent correlation between the relative proportion of a single FA and light intensity. The major fatty acids of the 6 strains were 14:0, 16:0, 16:l(n- 7) and 20:5(n-3) . Cylindrothecafusiformis had high percentage of 20:4n - 6 (9.2 - 10.9% ) . The total polyunsaturated fatty acid /rl all 6 strains decreased with increasing light intensity. The percentage of the highly unsaturated fatty acid eicosapentaenoic acid (EPA) decreased with increasing light intensity in all strains except Chaetoceros gracilis.     

Effect of growth phase on the fatty acid compositions of four species of marine diatoms

The fatty acid compositions of four species of marine diatoms (Chaetoceros gracilis MACC/B13, Cylindrotheca fusiformis MACC/B211, Phaeodactylum tricornutum MACC/B221 and Nitzschia closterium MACC/B222), cultivated at 22 ℃±1 ℃ with the salinity of 28 in f/2 medium and harvested in the exponential growth phase, the early stationary phase and the late stationary phase, were determined. The results showed that growth phase has significant effect on most fatty acid contents in the four species of marine diatoms. The proportions of 16:0 and 16: 1n-7 fatty acids increased while those of 16 :3n-4 and eicosapentaenoic acid (EPA) decreased with increasing culture age in all species studied. The subtotal of saturated fatty acids (SFA) increased with the increasing culture age in all species with the exception of B13. The subtotal of monounsaturated fatty acids (MUFA) increased while that of polyunsaturated fatty acids (PUFA) decreased with culture age in the four species of marine diatoms. MUFA reached their lowest value in the exponential growth phase, whereas PUFA reached their highest value in the same phase.     

EFFECTS OF HARVEST STAGE ON THE TOTAL LIPID AND FATTY ACID COMPOSITION OF FOUR CYLINDROTHECA STRAINS

Four strains of Cylindrotheca (B156, B164, B196, and B200) were harvested at three phases in the growth curve and their total lipid and fatty acid composition were determined. Total lipid reached highest values in the late stationary phase in B156 (24.0%), B164 (26.6%) and B200 (17.3%), in the exponential phase in B196 (15.5%). Saturated fatty acids increased with the devel-opment of the culture in B156 and B196, and reached their highest values in the late stationary phase in B156 (41.7%) and B196 (45.1%), in the early stationary phase in B164 (45.4%) and B200 (37.6%). Monounsaturated fatty acids increased with the development of the culture in B196 and B200, and reached their highest values in the late stationary phase in B196 (32.4%) and B200 (32.8%), in the early stationary phase in B164 (31.0%) and in the exponential phase in B156 (29.3%). Polyunsaturat-ed fatty acids decreased in the later phases of the culture in B164, B196 and B200, and peaked in theexponential phase in B164 (29.5%), B196 (42.9%) and B200 (37.3%), and in the early stationary phase in B156 (32.0%).     

Monthly changes of glycogen, lipid and free amino acid of oyster

Monthly difference of the chemical composition of oyster cultured along the eastern coast of Shandong Province was analyzed. The components analyzed included glycogen, fatty acid and free amino acid （FAA）. The content of glycogen was high in January and March （2.89 and 2.82 g（100 g） ^-1 on average, respectively） and low in October （2.07g（100g）^- 1 on average）. The low content of neutral lipids in October reflected a relatively poor nutritional value of oyster （1.42 g（ 100 g）^- 1 on average）. The main fatty acids of oyster were palmitic acid （16：0）, oleic acid （18： 1）, eicosapentaenoic acid （EPA, 20： 5（0 3） and docosahexaenoic acid （DHA, 22：6（0 3）. The major FAAs of oyster were Taurine, Glutamicacid, Glycin, Alanine, Arginine and Proline. Taurine was the most abundant FAA with its content ranging from 603 mg（100 g） ^-1 to 1 139 mg（ 100 g） ^-1. The high contents of glycogen, polyunsaturated fatty acid and FAA showed that oyster cultured along the eastern coast of Shandong Province was nutritionally good in January and March.     

Responses in growth, lipid accumulation, and fatty acid composition of four oleaginous microalgae to different nitrogen sources and concentrations

Nitrogen deficiency is an effective strategy for enhancing lipid production in microalgae. Close relationships exist among lipid production, microalgal species, and nitrogen sources. We report growth, lipid accumulation, and fatty acid composition in four microalgae （Chloroeoccum ellipsoideum UTEX972, Chlorococcum nivale LB2225, Chlorococcum tatrense UTEX2227, and Scenedesmus deserticola JNU19） under nitrate- and urea-nitrogen deficiencies. We found three patterns of response to nitrogen deficiency： Type-A （decrease in biomass and increase in lipid content）, Type-B （reduction in both biomass and lipid content）, and Type-C （enhancement of both biomass and lipid content）. Type-C microalgae are potential candidates for large-scale oil production. Chlorococcum ellipsoideum, for example, exhibited a neutral lipid production of up to 239.6 mg/（L＇d） under urea-nitrogen deficiency. In addition, nitrogen deficiency showed only a slight influence on lipid fractions and fatty acid composition. Our study provides useful information for further screening hyper-lipid microalgal strains for biofuel production.     

金枪鱼油的精炼工艺对脂肪酸组成的影响

粗鱼油通过精炼可以除去非甘油三酯杂质成分,研究表明黄鳍金枪鱼鱼油精炼的工艺参数为:800 g/L的H3PO4脱胶,添加量为油量的1%(体积分数);300 g/L的NaOH脱酸,添加量为油量的2%(体积分数);活性土脱色,添加量为油量的10%(质量分数);85℃下减压蒸馏脱臭15 min。经过精炼,鱼油呈淡黄色,澄清透明,有淡鱼腥味,理化指标达到鱼油SC/T3502-2000标准的精制鱼油一级要求,精制鱼油中PUFA的总含量(w)达37.06%,DHA和EPA含量(w)分别为25.10%和4.45%。