Microalgae for use in tropical aquaculture I: Gross chemical and fatty acid composition of twelve species of microalgae from the Northern Territory,Australia

Twelve species of microalgae, isolated from north Australian marine, freshwater and hypersaline environments, were grown under controlled conditions of temperature, pH, photon flux density and salinity, and analysed for ash, total protein, water soluble carbohydrates, chlorophylla, total lipids, total fatty acids and fatty acid composition. Highest levels of the polyunsaturated fatty acid eicosapentaenoic acid [20:5(n-3)] were found in the marine diatoms.Nitzschia (frustulum) andN. closterium (23.1% and 15.2% of total fatty acids, respectively). None of the species studied had levels of docosahexaenoic acid [22:6(n-3)] greater than 1.1 % of total fatty acids. None of the chlorophyte species contained significant levels of either 20:5(n-3) or 22:6(n-3). The highest total fatty acid concentration of all species in the study was found in the freshwater chlorophyte speciesScenedesmus dimorphus (105 mg g^–1 dry wt). The hypersaline speciesDunaliella salina had the highest total lipid content (28.1% dry wt), followed byN. closterium, N. (frustulum) andNavicula sp. (24.2–27.8% dry wt).Chlamydomonas sp. had the highest protein content (66.9% dry wt).N. (frustulum) was highlighted as a possible useful source of lipids and polyunsaturated fatty acids in mixed microalgal diets for mariculture organisms used in tropical aquaculture.Author for correspondence     

Total fatty acid composition as a taxonomic index of some marine microalgae used as food in marine aquaculture

Total lipid and total fatty acid composition was studied in twelve marine microalgae species, belonging to the Eustigmatophyceae, Chlorophyceae, Haptophyceae and Prasinophyceae, cultured under comparable conditions.Species of the same class showed a particular fatty acid composition, indicating specific fatty acid bioconversion modes. The fatty acid composition of the different microalgae was compared to previously published data.     

Growth,lipid content,productivity, and fatty acid composition of tropical microalgae for scale‐up production

Biomass and lipid productivity, lipid content, and quantitative and qualitative lipid composition are critical parameters in selecting microalgal species for commercial scale‐up production. This study compares lipid content and composition, and lipid and biomass productivity during logarithmic, late logarithmic, and stationary phase of Nannochloropsis sp., Isochrysis sp., Tetraselmis sp., and Rhodomonas sp. grown in L1‐, f/2‐, and K‐medium. Of the tested species, Tetraselmis sp. exhibited a lipid productivity of 3.9–4.8 g m^?2 day^?1 in any media type, with comparable lipid productivity by Nannochloropsis sp. and Isochrysis sp. when grown in L1‐medium. The dry biomass productivity of Tetraselmis sp. (33.1–45.0 g m^?2 day^?1) exceeded that of the other species by a factor 2–10. Of the organisms studied, Tetraselmis sp. had the best dry biomass and/or lipid production profile in large‐scale cultures. The present study provides a practical benchmark, which allows comparison of microalgal production systems with different footprints, as well as terrestrial systems. Biotechnol. Bioeng. 2010;107: 245–257. © 2010 Wiley Periodicals, Inc.     

Effects of salinity on cell growth and docosahexaenoic acid content of the heterotrophic marine microalga Crypthecodinium cohnii

The effects of salinity on cell growth and docosahexaenoic acid (DHA) content of three marine microalgal strains, Crythecodinium cohnii ATCC 30556, C. cohnii ATCC 50051 and C. cohnii RJH were investigated. The lag phases of the three strains increased with increasing salinity in Porphyridium medium. The specific growth rate of C. cohnii ATCC 30556 was the highest at 9 g L⁻¹ NaCl while the other two strains had their highest specific growth rates at 5 g L⁻¹ NaCl. The highest cell dry weight concentrations of 2.51 g L⁻¹ and 1.56 g L⁻¹ were achieved at 9 g L⁻¹ NaCl for C. cohnii ATCC 30556 and ATCC 50051, respectively, while the highest dry weight concentration of 2.49 g L⁻¹ was achieved at 5 g L⁻¹ NaCl for C. cohnii RJH. The highest cell growth yield coefficient on glucose was 0.5 g g⁻¹ for both C. cohnii ATCC 30556 and C. cohnii RJH and 0.45 g g⁻¹ for C. cohnii ATCC 50051. All three strains responded to the change of salinity by modifying their cellular fatty acid compositions. At 9 g L⁻¹ NaCl, C. cohnii ATCC 30556 had the highest total fatty acid content and DHA (C22:6) proportion. In contrast, C. cohnii ATCC 50051 and C. cohnii RJH had the highest DHA content at 5 g L⁻¹ NaCl. C. cohnii ATCC 30556 and ATCC 50051 had the highest DHA yield (131.55 and 68.24 mg L⁻¹ respectively) at 9 g L⁻¹ NaCl while C. cohnii RJH had the highest DHA yield (128.83 mg L⁻¹) at 5 g L⁻¹ NaCl. Received 27 May 1999/ Accepted in revised form 27 August 1999     

Effect of temperature on the growth,total lipid content and fatty acid composition of recently isolated tropical microalgae Isochrysis sp., Nitzschia closterium,Nitzschia paleacea,and commercial species Isochrysis sp. (clone T.ISO)

The effect of temperature from 10 °C to 35 °C on the growth, total lipid content, and fatty acid composition of three species of tropical marine microalgae, Isochrysis sp., Nitzschia closterium, N. paleacea (formerly frustulum), and the Tahitian Isochrysis sp. (T.ISO), was investigated.Cultures of N. closterium, Isochrysis sp. and T.ISO grew very slowly at 35 °C, while N. closterium did not grow at temperatures higher than 30 °C or lower than 20 °C. N. paleacea was low-temperature tolerant, with cells growing slowly at 10 °C. N. paleacea produced the highest percentage of lipids at 10 °C, while the other species produced maximum amounts of lipid at 20 °C. None of the species maintained high levels of polyunsaturated fatty acids (PUFAs) at high growth temperature and there was a significant inverse relationship between the percentage of PUFAs and temperature for N. paleacea. A curved relationship was found between temperature and percentage of PUFA for N. closterium and tropical Isochrysis sp., with the maximum production of PUFA at 25 °C and 20 °C, respectively. The two Nitzschia species produced higher levels of the essential fatty acid eicosapentaenoic acid [20:5(n-3)] at lower growth temperatures, but the two Isochrysis species had little change in percentage of 20:5(n-3) with temperature. Only T.ISO had the highest percentage of 22:6(n-3) at lowest growth temperature (11.4% total fatty acids at 10 °C).School of Mathematical and Physical SciencesAuthor for correspondence     

Lipid and fatty acid composition of microalgae used in Malaysian aquaculture as live food for the early stage of penaeid larvae

The total ash, chlorophyll, phaeopigment, lipid and fatty acid contents of three microalgae (the diatomsChaetoceros calcitrans, Skeletonema costatum and the prymnesiophyteIsochrysis galbana) used in tropical Malaysian penaeid mariculture were studied. The axenic laboratory cultures were grown in f-2 medium, while outdoor cultures were grown in a commercial medium designed for optimum nutrition in tropical outdoor aquaculture operations. Considerable amounts (3–9% of the total fatty acid) of the polyunsaturated fatty acid 20:5w3 (eicosapentaenoic acid) were present in the diatoms; very small amounts were also found inI. galbana. Lipid contents were three to five times higher than chlorophylla. There was an increase with culture age in the relative proportion of total C18 and C20 fatty acid components. The algae contained the w3-polyunsaturated fatty acids (PUFA) necessary for the growth and survival rate of the prawn larvae. However, onlyChaetoceros calcitrans grew well under the conditions of temperature and salinity in the hatchery.     

Effect of light intensity on the proximate biochemical and fatty acid composition of Isochrysis sp. and Nannochloropsis oculata for use in tropical aquaculture

The total protein, carbohydrate, lipid and ash compositions, and fatty acid contents of two species of marine microalgae, the eustigmatophyte Nannochloropsis oculata (formerly ‘Chlorella sp., Japan’) and the chrysophyte Isochrysis sp. (Tahitian) used in tropical Australian mariculture, were studied. The microalgae were grown under a range of culture conditions (41 and 601 laboratory culture, 3001 bag culture, and 80001 outdoor culture) and four light regimes (100 to 107 μ E m⁻² s⁻¹, 240 to 390 μ E m⁻² s⁻¹, 340 to 620 μ E m⁻² s⁻¹, and 1100 to 1200 μE m⁻² s⁻¹ respectively) to determine the effect of light intensity on the chemical composition of large scale outdoor cultures. Laboratory and bag cultures were axenic and cultured in Walne medium while outdoor cultures were grown in a commercial medium designed for optimum nutrition in tropical outdoor aquaculture operations. Change in growth medium and photon flux density produced only small changes in the proximate biochemical composition of both algae. N. oculata and Isochrysis sp. both showed a trend towards slightly lower carbohydrate and higher chlorophyll a in shaded outdoor culture. Isochrysis sp. showed significant concentrations of the essential polyunsaturated fatty acid 22:6(n−3) (docosahexaenoic acid) from 5.3 to 10.3% of total fatty acid, and 20:5(n−3) (eicosapentaenoic acid) ranged from 0.6 to 4.1%. In contrast, N. oculata had high concentrations of 20:5(n−3) (17.8 to 39.9%) and only traces of 22:6(n−3). The fatty acid composition of Isochrysis sp. grown at high photon flux density (1100–1200 μE m⁻² s⁻¹) under outdoor culture showed a decrease in the percentage of several highly unsaturated fatty acids, including 20:5(n−3), and an increase in 22:6(n−3). N. oculata showed a similar decrease in the percentage of 20:5(n−3). High light intensity caused a decrease in the ratio of total C₁₆ unsaturated fatty acids to saturated 16:0 in N. oculata, and a decrease in the ratio of total C₁₈ unsaturated fatty acids to saturated 18:0 together with a decrease in the ratio of total unsaturated fatty acids to total saturated fatty acids in both microalgae.     

The amino acid and gross composition of marine diatoms potentially useful for mariculture

The amino acid and gross compositions of three benthic diatoms (Cylindrotheca fusiformis Reimann and Lewin, Navicula jeffreyi Hallegraeff et Burford and Nitzschia closterium (Ehr. W. Smith) and three chain-forming diatoms (Lauderia annulata Cleve, Skeletonema costatum (Greville) Cleve and a tropical Skeletonema sp. (CS-252)), were determined during late-logarithmic growth phase.Four of the six species were rich in protein, ranging from 31% (S. costatum) to 38% (N. closterium) of the dry weight, and contained 4.9 to 6.5% carbohydrate and 9.4 to 18% ash. The other two species, C. fusiformis and L. annulata contained only 16% protein but had nearly twice the total carbohydrate (11 to 12%) and two to three times the ash (29 to 35%) of the other species. All species contained a similar percentage of lipid (18 to 20%), and a high protein quality based on their total amino acid composition.The usefulness of these diatoms for mariculture will be determined by growth rates, gross composition and acceptability to the animal. N. closterium had the fastest growth rates of the benthic mat-forming diatoms, it was rich in protein, and it may be a good candidate for abalone culture. The two Skeletonema spp. had the fastest growth rates of the chain-forming diatoms, and are already widely used for prawn larval culture in Australia. Feeding trials are now necessary to confirm the high nutritional value of these diatom species for specific animals.     

温度、光照和盐度对2株曼氏骨条藻生长及脂肪酸组成的影响

研究温度、光照、盐度对2株曼氏骨条藻（Skeletonema munzelii）SM-1、SM-2生长、总脂含量及脂肪酸组成的影响,以确定其生长及油脂、多不饱和脂肪酸积累的最适生态条件。在实验室智能光照培养箱内不充气培养控制条件下,采用单因子试验分别研究了不同温度（10、15、20、25和30℃）、光照强度（20、40、60、80、100和120μmol/m2·s）、盐度（10、15、20、25、30、35和40）对2株藻的生长、总脂含量及脂肪酸组成的影响。结果表明：不同温度、光照强度及盐度对2株藻的生长、总脂及脂肪酸含量影响均有显著影响（P〈0.05）。藻株SM-1生长的最适温度为25℃,最适光强60μmol/m2·s,最适盐度30,而低温（10~15℃）,低光照（20μmol/m2·s）,低盐度（盐度15）更有利于总脂及PUFA的积累。SM-2生长的最适温度为20℃,最适光强60μmol/m2·s,最适盐度30,而低温（10~15℃）,低光照（20μmol/m2·s）更有利于其总脂及PUFA的积累,低盐（盐度15）则更有利于PUFA的积累。因此在实际生产中,2株藻可先在最适条件下培养以增加生物量,后转至利于PUFA积累的条件下提高PUFA产量。     

分离自象山港的15种海洋微藻脂肪酸比较研究

在160μmol.m-2.s-1光强、（20±2）℃条件下对分离自象山港的15种海洋微藻进行培养,在稳定期离心收集,冷冻干燥后用Bligh-Dyer法提取总脂,皂化衍生化后用气相色谱-质谱联用分析系统对其含有的脂肪酸进行定量和定性的分析。结果表明,这15种微藻总脂含量均较高,其中有9种微藻的总脂含量超过干重的10%,中心硅藻纲中共有的含量相对较高的主要脂肪酸为C14∶0、C16∶0、C16∶1（n-7）脂肪酸和EPA,针胞藻纲的赤潮异湾藻则含有高比例的C16∶0、C18∶4（n-3）和EPA,纵裂甲藻纲和甲藻纲中共有的含量相对较高的主要脂肪酸为C16∶0、C18∶4（n-3）、C18∶5（n-3）和DHA,而隶属于定鞭藻门颗石藻纲的颗石藻含量相对较高的主要脂肪酸分别为C16∶0、C18∶4（n-3）和DHA。这些藻是否可以作为生物饵料还需实际养殖投喂效果决定。     

Effect of salinity of medium on cellular fatty acid composition of marine algaPorphyridium cruentum (Rhodophyceae)

Porphyridium cruentum Näg. (clone 161) was found to grow best in medium containing between 0.45 M and 0.8 M NaCl. From studies done on growing cultures, the palmitic acid content of the cells decreased with increasing NaCl concentration of the medium. Conversely, when the culture was transferred from a 0.8 M NaCl medium to 0.2 M NaCl, the amount of palmitic acid in thePorphyridium cells increased with time of incubation and it contributed up to 64.5% of the total fatty acid content. There appears to be a negative correlation between the cellular content of palmitic acid and the growth lag. The oleic acid content varied only marginally with increasing NaCl concentration. The poly-unsaturated acid content (linolenic and arachidonic acids) decreased initially and then increased with NaCl concentration up to and beyond ca. 0.8 M NaCl respectively. At 1.5 M NaCl, the poly-unsaturated fatty acids amounted to 78.2% of the total fatty acids in the cell. For stationary phaseP. cruentum cultures, a similar relationship existed between fatty acids and NaCl concentration. However, palmitic acid was accumulated up to three-fold more when compared to the exponential culture grown in low salinity. In addition stearic acid was also found in significant quantities.     

5株新分离海洋硅藻总脂和脂肪酸组成的比较研究

从浙江渔山列岛、朱家尖海域拖网采集浮游植物,采用平板分离法和水滴分离法分离、纯化出5株硅藻,用MAV培养基进行培养,采用Bligh—Dyer法和气相色谱-质谱法,对5株海洋硅藻的总脂及脂肪酸组成进行了分析比较。结果表明：在水温17—25℃,盐度25,自然光照,不充气培养条件下,5株海洋硅藻的总脂含量为15．14％-28．07％,除成对海链藻（Thalassiosirabinata）外,大龙骨藻（Tropidoneismaxima）、咖啡双眉藻（Amphoracoffeaeformis）、曼氏骨奈藻SM-2012—1（Skeletonemamunzelii）、曼氏骨条藻SM-2012-2（Skeletonemamunzelii）的总脂含量均超过其干重的20％。除咖啡双眉藻的20：4n_6含量高于20：5n4外,其它4株硅藻的20：5n．3在脂肪酸组成中含量较高,达22．04％-27．74％;5株硅藻中C18系列脂肪酸含量较低,为0．13％-7．6％;咖啡双眉藻除外的其它4株硅藻均舍有一定量的22：6n-3（2．40％-3．45％）。最终选出大龙骨藻（Tropidoneis maxima）、曼氏骨条藻SM-2012-1（Skeletonemamunzelii）、曼氏骨条藻SM-2012-2（Skeletonemamunzelii）具有开发的潜能。     

Effect of feeding and lack of food on the growth, gross biochemical and fatty acid composition of juvenile catfish

The effect of feeding and starvation on growth, gross body composition and fatty acid composition of body muscle and liver were investigated in juvenile African catfish ( Clarias gariepinus ). The relative composition of fatty acids was influenced by starvation. In both liver and muscle there were marked relative decreases of 14: 0, 16: 1n9 and 18: 1n9 fatty acids and relative increases of 20: 5n3 and 22: 6n3 when these were compared to the controls. Preference of utilization of fatty acids from liver and body muscle during starvation was highest for 14: 0>16: 1n9>18: 1n9 and conservation highest for 22: 6n3>20: 5n3. The changes of these fatty acids were smaller in muscle than in the liver.     

Use of freeze-dried microalgae for rearing gilthead seabream, Sparus aurata L., larvae. II. Biochemical composition

The objectives of this study were to test whether freeze-dried microalgae are nutritionally adequate for rearing rotifers as food for gilthead seabream larvae. The elemental composition (C, N, H) and fatty acid composition were analysed in larvae of gilthead seabream, Sparus aurata L., rotifers Brachionus plicatilis and Brachionus rotundiformis and freeze-dried microalgae Nannochloropsis oculata. Four larval feeding treatments were tested: (A) larvae fed rotifers cultivated with freeze-dried microalgae and daily addition of freeze-dried microalgae to the larval tanks; (B) larvae fed rotifers cultivated with freeze-dried microalgae and daily addition of live microalgae to the larval tanks; (C) larvae fed rotifers cultivated with freeze-dried microalgae, without addition of microalgae to the larval tank and (D) larvae fed rotifers cultivated with live microalgae and daily addition of live microalgae to the larval tanks. No significant differences were observed between the biochemical composition of larvae with treatment A (with freeze-dried microalgae) and the composition of larvae in treatment D that were obtained with the acceptable methods for culture systems (with live microalgae).     

Influence of culture temperature on the growth,biochemical composition and fatty acid profiles of six Antarctic microalgae

The growth, biochemical composition and fatty acid profiles of six Antarctic microalgae cultured at different temperatures, ranging from 4, 6, 9, 14, 20 to 30 ^∘C, were compared. The algae were isolated from seawater, freshwater, soil and snow samples collected during our recent expeditions to Casey, Antarctica, and are currently deposited in the University of Malaya Algae Culture Collection (UMACC). The algae chosen for the study were Chlamydomonas UMACC 229, Chlorella UMACC 234, Chlorella UMACC 237, Klebsormidium UMACC 227, Navicula UMACC 231 and Stichococcus UMACC 238. All the isolates could grow at temperatures up to 20 ^∘C; three isolates, namely Navicula UMACC 231 and the two Chlorella isolates (UMACC 234 and UMACC 237) grew even at 30 ^∘C. Both Chlorella UMACC 234 and Stichococcus UMACC 238 had broad optimal temperatures for growth, ranging from 6 to 20 ^∘C (μ = 0.19 – 0.22 day^–1) and 4 to 14 ^∘C (μ = 0.13 – 0.16 day^–1), respectively. In contrast, optimal growth temperatures for NaviculaUMACC 231 and Chlamydomonas UMACC 229 were 4 ^∘C (μ = 0.34 day^–1) and 6–9 ^∘C (μ = 0.39 – 0.40 day^–1), respectively. The protein content of the Antarctic algae was markedly affected by culture temperature. All except Navicula UMACC 231 and Stichococcus UMACC 238 contained higher amount of proteins when grown at low temperatures (6–9 ^∘C). The percentage of PUFA, especially 20:5 in Navicula UMACC 231 decreased with increasing culture temperature. However, the percentages of unsaturated fatty acids did not show consistent trend with culture temperature for the other algae studied.     

Effect of long chain fatty acids on triacylglycerol accumulation,fatty acid composition and related gene expression in primary cultured bovine satellite cells

Abstract

This study was conducted to determine the effects of long chain fatty acids (LCFAs) on triacylglycerol (TAG) content, as well as on genes associated with lipid synthesis and fatty acid composition in bovine satellite cells. Both saturated (palmitic and stearic) and unsaturated (oleic and linoleic) fatty acids stimulated the TAG accumulation at a concentration of 100?µM and oleate increased it significantly more than stearate and palmitate. The results revealed that the lipid droplet formation was markedly stimulated by linoleate and oleate at 100?µM. Compared to control, the expressions of adipose triglyceride lipase, carnitine acyltransferase 1 and the fatty acid translocase 36 were upregulated by LCFAs. All the fatty acids also significantly increased diacylglycerol acyltransferase 2 than the untreated control (p?<?0.05). The monounsaturated fatty acids significantly increased (p?<?0.05) in response to oleate and linoleate compared to the control as did the polyunsaturated fatty acids (p?<?0.05), in addition to stearate, linoleate and oleate. In contrast, saturated fatty acids were significantly decreased in the oleate and linoleate-treated groups. The study results contribute to our enhanced understanding of LCFAs’ regulatory roles on the bovine cell lipid metabolism.     

In vitro culture and conservation of microalgae: Applications for aquaculture, biotechnology and environmental research

Summary Microalgae are a highly diverse group of unicellular organisms comprising the eukaryotic protists and the prokaryotic cyanobacteria or blue-green algae. The microalgae have a unique environmental status; being virtually ubiquitous in euphotic aquatic niches, they can occupy extreme habitats ranging from tropical coral reefs to the polar regions, and they contribute to half of the globe’s photosynthetic activity. Furthermore, they form the basis of the food chain for more than 70% of the world’s biomass. Microalgae are a valuable environmental and biotechnological resource, and the aim of this review is to explore the use of in vitro technologies in the conservation and sustainable exploitation of this remarkable group of organisms. The first part of the review evaluates the importance of in vitro methods in the maintenance and conservation of microalgae and describes the central role of culture collections in applied algal research. The second part explores the application of microalgal in vitro technologies, particularly in the context of the aquaculture and biotechnology industries. Emphasis is placed upon the exploitation of economically important algal products including aquaculture feed, biomass production for the health care sector, green fertilizers, pigments, vitamins, antioxidants, and antimicrobial agents. The contribution that microalgae can make to environmental research is also appraised; for example, they have an important role as indicator organisms in environmental impact assessments. Similarly, designated culture collection strains of microalgae are used for ecotoxicity testing. Throughout the review, emphasis is placed on the application of in vitro techniques for the continued advancement of microalgal research. The paper concludes by assessing future perspectives for the novel application of microalgae and their products.     

Effect of growth temperature and media composition on the fatty acid composition of Bacillus stearothermophilus AN 002

The influence of growth temperature, media composition and cell age on the chemical composition of Bacillus stearothermophilus strain AN 002 has been determined. The total cellular protein decreased and the free amino acid content increased with growth temperature, in both exponential and stationary growth phase. The protein and free amino acid contents of cells were higher in the stationary phase than in the exponential phase, irrespective of growth temperature and media composition. The RNA content was only reduced in cells grown at 55° C. No significant variations were observed in the DNA and carbohydrate contents with respect to growth temperature and cell age. The total lipid and fatty acid compositions on the other hand varied as a function of growth temperature, cell age and media composition. Differences in the relative concentrations of even, odd and branched chain fatty acids were noticed. Novariation was observed in the antiiso and unsaturated fatty acids with respect to growth temperature. The unique variations in the fatty acid composition and total lipids at the growth temperature of 50° C and their variations in the stationary growth phase seem to be characteristic for B. stearothermophilus AN 002.     

Effect of growth temperature and salt concentration on the fatty acid composition of Flavobacterium halmephilum CCM2831

Abstract In this study the fatty acid composition of Flavobacterium halmephilum CCM2831 grown at different temperatures and salt concentrations is reported. At elevated growth temperatures the amount of cellular saturated long-chain acids (C_18:0 and C_20:0) and the branched-chain acid br-C_17:0 increased, and the concentrations of both cyclic acids and the branched chain acid br-C_15:0 decreased. Increasing the salt concentration in the medium resulted in a gradual increase in cellular cyclopropanoic acids and a concomitant decrease in the monounsaturated fatty acid content.