Search

Algae are natural sources of nutrients, but the presence of anti-nutritional factors often compromises nutrient apparent digestibility coefficients (ADCs) in several fish species. In this study, physical-mechanical and enzymatic technological processing was applied to two seaweeds (Gracilaria gracilis and Ulva rigida) and three microalgae (Nannochloropsis oceanica, Chlorella vulgaris, and Tetraselmis sp.) in order to evaluate its effectiveness in improving nutrient ADC values in diets for European seabass. A practical commercial-based diet was used as reference (REF) and experimental diets were prepared by replacing 30% of REF diet with each test alga used either intact or after processing. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and fast performance liquid chromatography (FPLC) analyses revealed that enzymatic processing was more effective than the physical one in changing the protein and peptides composition, increasing the amount of low-molecular-weight compounds in seaweeds and N. oceanica microalgae. Protein digestibility was significantly affected by algae species and in the case of the microalgae by the technological process. Gracilaria gracilis is better digested than U. rigida and physical processing enhanced protein and energy ADC values. Nannochloropsis oceanica and C. vulgaris are better digested than Tetraselmis sp.; the highest protein and energy ADCs were observed in diets containing enzymatically processed N. oceanica (NAN-ENZ) and physically processed C. vulgaris (CHLO-PHY), followed by the diet with physically processed Tetraselmis sp. (TETR-PHY). Results clearly showed that it is possible to increase nutrient accessibility and digestibility of algae by fish, by selecting the most adequate method to disrupt the cell wall. Moreover, the physical-mechanical and enzymatic technological processes used in this study are scalable to the industrial level.

The investigation on combustion characteristic and kinetic parameters of Tetraselmis chuii microalgae was carried out under thermogravimetric analyzer. The sample of microalgae has prepared by the Center for Brackish Water Aquaculture (BBPBAP) Jepara, Indonesia. The drying out the water content in the sediment was performed by an oven at temperature 80 °C as long as 24 h. The dry sample then the crushed and followed by sieving to be mesh size of 60. The thermal decomposition of Tetraselmis chuii microalgae was investigated by a thermogravimetric apparatus, in which the 10 mg of sample was heated up in the temperatures range of 25-900 °C with an atmospheric airflow rate of 50 mL/min and a heating rate of 15 °C/min. The mass loss during temperature expansion was recorded by a computer to be a thermogravimetric (TG) graph and used to evaluate the thermal characteristic of the sample. The kinetic parameters were evaluated in the active combustion zone by the Arrhenius method, resulted in the respective values of reaction order (n), logarithmic frequency factor (log A), and activation energy (E) were 1.24, 9.0 min−1 and 101.05 kJ mol−1 for stage II, and 2.38, 33.31 min−1 and 502.88 kJ mol−1 for stage IV.

Hydrothermal liquefaction (HTL) of biomass is an emerging technology that is being developed to produce renewable crude oil in water at sub-critical conditions. Different feedstocks and reaction conditions result in different product fractions of renewable crude and co-products of solid, aqueous and gas phase products. Biomass considered as feedstocks for HTL include microalgae, sewage sludge and lignocelluloses. Each of these biomass sources contains varying amounts of lipid, carbohydrate, protein and lignin organic fractions as well as some inorganic components. To develop a bulk kinetic model to predict the yields of crude, solid, aqueous and gas phase products, HTL experiments were conducted at reaction temperatures of 250, 300 and 350 °C over reaction times of 0–60 min with Tetraselmis sp. microalgae, sewage sludge and Radiata pine. The crude was analysed via gas-chromatography mass-spectrometry to identify variations in the compounds in the crude produced from different types of biomass. The highest crude yield was produced from algae at up to 30%, followed by up to 25% from sludge and up to 10% from pine. A reaction temperature of 300 or 350 °C was preferable for maximum crude yield and increasing reaction time over 5 min was seen to cause minimum variation in crude yield for most cases. The variation in product distribution is strongly dependent on both the organic and inorganic content of the biomass feedstock. A unified bulk kinetic model for prediction of crude yield from a wide range of biomass was developed. Predictions showed up to 15% variation from measurements illustrating that further experimental data from HTL of a wider range of feedstocks are required to refine the model and build up model rigour.

Microalgae can grow effectively on various wastewaters, including those generated in aquaculture as a result of operation of hatcheries and farming systems. These organisms are able to remove pollutants from their growth environment, while the biomass produced can be further exploited. Such biomass contains lipids rich in polyunsaturated fatty acids and other substantial nutrients and can be used as a live feed in shrimp farming or in fisheries, i.e. as live feed for zooplankton or as fish feed supplement after enzymatic and/or chemical treatment. In the current work, a shrimp farm wastewater (SFW) with high nutrient (P, N) concentrations was used as growth medium for six newly isolated marine microalgae strains from Saudi Arabian coastal waters, including Chlorella sp., Dunaliella sp., Nannochloropsis sp., Navicula sp. (two strains) and Tetraselmis sp.. The growth yields and kinetics parameters were compared to those obtained in synthetic f/2 medium. Among these strains, Navicula sp. (both strains) and Tetraselmis sp. were able to grow well on SFW, producing high lipid quantities (especially Navicula sp. 1) containing polyunsaturated fatty acids, including eicosapentaenoic acid. However, microalgae lipids produced in SFW medium were in general more saturated than those produced in f/2 medium. It seems that several desaturases, of both the C16 and C18 group, and probably the C16:0 elongase, were inhibited in SFW medium modifying accordingly the fatty acid profile. Considering the overall physiological behavior of the strains, including biomass yields and fatty acid composition, we conclude that SFW can be valorized in a sustainable way for microalgae production in fisheries.

The aim of this study was to isolate and characterize the extracellular polysaccharides (EPS) from defatted microalga Tetraselmis KCTC 12236 BP (T1) and Tetraselmis KCTC 12432 BP (T2), both were isolated and used microalgal biomasses for the production of biodiesel. The difference of molecular diversity of EPS in T1 were obviously observed from each sample based on MALDI-TOF mass spectra analysis. Higher productivity and significant antioxidant activity were only observed from the EPS isolated from T1 than that of T2. Therefore, EPS from T1 were used for further study to elucidate the relationship between the EPS and its biological activity. These results suggest the importance of the understanding of primary structure to address the biological role of EPS in microalgal species.

In the photic zone, phytoplankton experience diurnal variation in light intensity. However, prolonged exposure to aphotic condition influences their physiological state. Pigment composition is a useful biomarker to decipher cells physiological state and adaptive response to changing environmental conditions. Chlorophyll, a natural pigment, is biosynthesised even in darkness and studies have shown this ability is determined by genetic characteristics of an organism. The purpose of this study was to examine the influence of darkness on pigments and chlorophyll autofluorescence of Tetraselmis indica. Dark exposure (up to 6 months) had no significant impact on chlorophyll a and b concentration, whereas carotenoids were enhanced. Upon re-illumination pigments gradually recovered to pre-dark phase condition. These adaptive survival strategies of T. indica by altering pigment concentration in response to prolonged darkness are interesting. The absence of loroxanthin and loroxanthin esters in T. indica is reported in a first Tetraselmis species so far. In addition, the evaluation of autofluorescence and cellular chlorophyll concentration pointed out that they are not interdependent in this species. Hence, careful consideration of these two factors is needed when either of them is used as a proxy for other. The results obtained encourage a thorough study of pigment analysis, especially when subjected to darkness, to elucidate potential role in the evolution, chemotaxonomy, and survivability of species.

This study reveal the combined effect of initial population density (IPD) (0.1, 0.5 and 1.0 g L−1) and nitrogen (0 N-nil nitrogen; 1 N-optimized concentration of nitrogen; 2 N–doubling of optimized nitrogen concentration) on growth, biomass, lipid and fatty acid content of the oceanic microalga Tetraselmis sp. were tested. The experiment was carried out in multi-room light-emitting diode chamber for two weeks with continuous illumination of light such as 14:10 h L:D of photoperiod (PP) and 150 μmol m−2 s−1 of photosynthetic photon flux intensity (PPFI). The maximum optical density (1.15 abs), cells concentration (253 × 104 cells mL−1), chlorophyll ‘a’ (2.68 mg L−1) and fatty acids content were found in the combination of 0.5 g L−1 initial population density and 1 N, whereas the highest biomass (0.95 g L−1) was noticed in 1 g L−1 initial population density and 2 N, and total lipid (48 ± 1.14%) was high in 0.5 g L−1 initial population density and 2 N combination.

Mariculture production has increased in the last decades, with untreated wastewater discharged directly into the sea, impacting coastal ecosystems. There is a need for mariculture wastewater treatment systems that are cost-effective. This can be met by the implementation of wastewater treatment systems that in addition to removing pollutants are capable of producing valuable by-products such as biomass for the biofuel industry. In this study, Dunaliella sp., Nannochloropsis sp. and Tetraselmis sp. microalgae were cultivated in controlled environments simulating mariculture wastewaters. Single stage culture systems were used to grow these microalgae, the growing conditions included inducing stress with different photon flux densities (900, 1500 and 2000 μmol m−2 s−1), and low carbon, nitrogen and phosphorus concentrations obtained at the stationary phase, in order to force these microalgae to increase their lipid content. The best results were obtained with Tetraselmis sp., which achieved 132.8 mg L−1 day−1 of biomass productivity at 900 μmol m−2 s−1. Nevertheless the best lipid productivity was reached at 1500 μmol m−2 s−1, also by Tetraselmis sp., being 29.5 mg L−1 day−1, where biomass productivity was of 124.5 mg L−1 day−1. All three microalgae species were able to remove >90% of nitrogen and orthophosphates, and 80% of carbon, which makes them suitable for treating mariculture wastewater, and in addition, represent a valuable high lipid content biomass byproduct usable as raw material for biodiesel synthesis.

Microalgae Tetraselmis species were used to evaluate the biological characteristics of water-soluble polysaccharides (WSPs) as one of the significant bioactive substances (BAS) from these photosynthetic microalgae species. Compositional analysis of these BAS shows that they are mainly composed of WSPs along with negligible amount of proteins and lipids. WSPs were partially purified and characterized for their compositional, structural and biological properties such as antioxidant, tyrosinase inhibitory activity and antifungal activies. These WSPs showed the significant antioxidant, antifungal and tyrosinase inhibitory activities, respectively. The outcomes of this study demonstrated that WSPs can be the potent source of biological moieties for further investigations along with specific potent biological activities.

This study aimed to investigate the potential of four sea water microalgae, isolated and cultivated at M&prime, diq Bay in Morocco, as a new source of natural antioxidants. These microalgae belong to different classes, including Phaedactylium tricornitum (Bacillariophyceae), Nannochloropsis gaditana (Eustigmatophyceae), Nannochloris sp (Trebouxiophyceae), and Tetraselmis suecica (Chlorodendrophycea). The antioxidant properties were screened by the use of in vitro assays, namely 2,2-difenil-1-picrylhydrazyl, Ferric reducing antioxidant power, and Ferrous ions chelating activity, and compoundidentification was carried out in methanol and acetone extracts of both dried and fresh microalgae biomass by HPLC&ndash, PDA&ndash, MS analysis. Among the investigated microalgae, Phaedactylium tricornutum was the richest one regarding its carotenoid (especially all-E-fucoxanthin) and phenolic (especially protocatechuic acid) contents, as well as antioxidant activity (65.5%), followed by Nannochloris sp, Tetraselmis suicica, and Nannochloropsis gaditana, with antioxidant activity of 56.8%, 54.9%, and 51.1%, respectively.

Biochemical composition of microalgae, a promising feedstock for biodiesel production, can be modified under different nutritional modes. The objective of this study was to investigate the influence of autotrophy and mixotrophy on the growth and biochemical composition of Tetraselmis sp. KY114885. Time-course variations of lipids and starch were determined using gravimetric and colorimetric methods. After direct transesterification, lipid profile on days 12 and 20 of cultivation period was determined. The results revealed higher growth of microalgae in mixotrophic cultures containing 5 g L−1 glucose, whereas 7.5 g L−1 glucose suppressed growth. Mixotrophy enhanced the lipid and starch yields in a distinctive trend. The fatty acid composition changed with the different nutritional regimes and the length of growth in batch culture. Glucose supplementation elevated the portions of monounsaturated fatty acids, particularly oleic acid, and decreased the percentage of saturated and polyunsaturated fatty acids. The present study suggests that mixotrophic cultivation of Tetraselmis sp. KY114885 may be a feasible strategy to improve growth parameters and the biochemical composition of the alga for biofuel production. The results also shed light on carbon allocation in the algae grown under two different trophic modes.

Microalgae could be of importance for future biodiesel production as an alternative for a third generation of biofuels. To select the most appropriate strain for biodiesel production, three microalgae species, namely Isochrysis sp., Nannochloropsis maritima and Tetraselmis sp., isolated from Tunisian coast, were biochemically characterized. Initially, gas chromatography analysis showed that Isochrysis sp. and N. maritima contained 5- and 10-fold total fatty acids, respectively, more than Tetraselmis sp. Then, the two microalgae Isochrysis sp. and N. maritima were subject to random mutagenesis using ultraviolet-C radiation. Subsequently, a total of 18 mutants were obtained from both species. The neutral lipid evaluation on said 18 mutants allowed the retention of only 7 to further fatty acid characterization. Finally, gas chromatography revealed that the mutant 5c Isochrysis sp. was characterized by a high level of saturated fatty acids (52.3%), higher amount of monounsaturated fatty acids (29.3%), lower level of polyunsaturated fatty acids (18.4%) and a significant 1.3-fold increase in its C16-C18 content compared to the wild-type strain, which would make it an interesting candidate for biofuel production.

Date palm (Phoenix dactylifera L.) is the main fruit crop found in the arid and semi-arid regions of the world. It naturally adapts to the adverse environments of extreme heat and water scarcity and prevents further desertification in addition to producing fruits with high nutritional value. It is seen in many parts of the world that traditional cultivation practices such as mixed planting and chemical fertilizers have led to low fruit quality resulting in low market values. Long generation time also hinders production of the dates. Tissue culture is therefore considered the most promising solution for rapid large-scale production of true-to-type clonal plants. The plantlets originating from in vitro callus proliferation are transferred from synthetic media to soil. The conventional method of using chemical fertilizers also leads to low plantlet viability with increased environmental and health risk. The current research targets the use of a local microalga, Tetraselmis sp. QUCCCM8, identified as an organic source of nutrients, a substitute for chemical fertilizers to acclimatize cultured date palmlets to soil. Soil was supplemented with different concentrations of algal biomass and plant growth was monitored for 3 months. Soil without any fertilizer and soil amended with 1 g conventional fertilizer were used as negative and positive control, respectively. Supplementation with 0.5 g of algal biomass led to higher plant growth rates, 100% survival rates, high ability of rooting (3.17 ± 0.14 roots), higher number of leaves (2.5 ± 0.25 leaves), largest stem thickness, longer shoot (33.75 ± 1.56 cm), and higher total chlorophyll (159.61 ± 9.6 mg L−1) as compared to conventional fertilizer. These stated findings are significantly higher than the control. Furthermore, elemental analysis of the soil showed that supplementation with algal biomass increased the soil total nitrogen, potassium, and phosphorus contents essential for plant growth. Finally, the comparison of heavy metals composition between soils amended with conventional fertilizer and algae-based fertilizer highlights the potential use of algae as a safe and efficient biofertilizer post tissue culture mode of plantlet generation. This enhanced the viability of healthy plantlets without affecting the environment, averting usage of chemical fertilizers. Funding information This report was made possible by the NPRP award [NPRP8-1087-1-207] from the Qatar National Research Fund (a member of The Qatar Foundation). Scopus

The present study aimed to triggering of growth, lipid and fatty acids production of oceanic microalgae Tetraselmis sp. for biofuel production under mutagenic treatment with ethyl methanesulfonate (EMS). The maximum optical density (0.51 ± 0.02), cells concentration (138 ± 6.9 × 104 cells mL−1), biomass (0.63 ± 0.03 g L−1), chlorophyll ‘a’ (3.91 ± 0.19 mg L−1) were found in DKMK06 in first generation which was treated with EMS at 50 μmol mL−1 for 60 min. DKMK06 was exhibited the highest lipid productivity (48 ± 0.9%) during first generation and DKMK05 during second and third generations and percentages of lipid were 46.5 ± 1.1 and 41 ± 1.1%. The same trend has been observed in FAME contents and highest saturated and mono unsaturated fatty acid combinations were found in DKMK05 in 2nd generation (42.49%) followed by third generation (41.5%) which were higher than the first generation produced by DKMK06 (39.98%).

Summary The composition of digestive microbiomes is known to be a significant factor in the health of a variety of hosts, including animal livestock. Therefore, it is important to ascertain how readily the microbiome can be significantly altered. To this end, the role of changing diet on the digestive microbiome of the Pacific oyster (Crassostrea gigas) was assessed via weekly faecal sampling. Over the course of 12 weeks, isolated individual oysters were fed either a control diet of Tetraselmis algae (Tet) or a treatment diet which shifted in composition every 4 weeks. Weekly faecal samples from all oysters were taken to characterize their digestive bacterial microbiota. Concurrent weekly sampling of the algal feed cultures was performed to assess the effect of algal microbiomes, independent of the algal type, on the microbiomes observed in the oyster samples. Changing the algal feed was found to be significantly associated with changes in the faecal microbiome over a timescale of weeks between control and treatment groups. No significant differences between individual microbiomes were found within control and treatment groups. This suggests the digestive microbiome of the Pacific oyster can be quickly and reproducibly manipulated.

Microalgae are cultured commercially as healthy food, cosmetic products, food preservatives, and a source of valuable compounds. However, the high cost of commercial culture medium is one of the challenges to microalgal production. Therefore, it is essential to find an alternative cost-effective culture medium. Aquaculture wastewater is considered as a highly potential candidate due to its high nutrient content and large quantity generated from the rapid growth of aquaculture sector. In this study, Tetraselmis chuii cultured in different media with or without wastewater was evaluated for its growth, proximate composition and carotenoid production. The results showed that significantly (P < 0.05) higher growth (4.3 × 105 cells mL−1) and protein (56.4% dry weight), lipid (44% dry weight) and carbohydrate (20% of dry weight) contents were found in T. chuii when they were cultured in the combination of both wastewater and Conway (wastewater + Conway) medium. However, carotenoid production of T. chuii was significantly increased (P < 0.05) when it was cultured in wastewater only, followed by Conway + wastewater and Conway medium only. Therefore, the incorporation of wastewater with commercial medium Convey is recommended for a cost-effective microalgae culture, as well as for the enhancement of growth and nutritional content of microalgae.

The Roseobacter-group species Phaeobacter inhibens produces the antibacterial tropodithietic acid (TDA) and the algaecidal roseobacticides with both compound classes sharing part of the same biosynthetic pathway. The purpose of this study was to investigate the production of roseobacticides more broadly in TDA-producing roseobacters and to compare the effect of producers and non-producers on microalgae. Of 33 roseobacters analyzed, roseobacticide production was a unique feature of TDA-producing P. inhibens, P. gallaeciensis and P. piscinae strains. One TDA-producing Phaeobacter, 27-4, did not produce roseobacticides, possibly due to a transposable element. TDA-producing Ruegeria and Pseudovibrio did not produce roseobacticides. Addition of roseobacticide-containing bacterial extracts affected the growth of the microalgae Rhodomonas salina, Thalassiosira pseudonana and Emiliania huxleyi, while growth of Tetraselmis suecica was unaffected. During co-cultivation, growth of E. huxleyi was initially stimulated by the roseobacticide producer DSM 17395, while the subsequent decline in algal cell numbers during senescence was enhanced. Strain 27-4 that does not produce roseobacticides had no effect on algal growth. Both bacterial strains, DSM 17395 and 27-4, grew during co-cultivation presumably utilizing algal exudates. Furthermore, TDA-producing roseobacters have potential as probiotics in marine larviculture and it is promising that the live feed Tetraselmis was unaffected by roseobacticides-containing extracts.

Microalgae hold promise as a renewable energy source for the production of biofuel, as they can convert light energy into chemical energy through photosynthesis. However, cost-efficient harvest of microalgae remains a major challenge to commercial-scale algal biofuel production. We first investigated the potential of electrolytic water as a flocculant for harvesting Tetraselmis sp. Alkaline electrolyzed water (AEW) is produced at the cathode through water electrolysis. It contains mineral ions such as Na+, K+, Ca2+, and Mg2+ that can act as flocculants. The flocculation activity with AEW was evaluated via culture density, AEW concentration, medium pH, settling time, and ionic strength analyses. The flocculation efficiency was 88.7% at 20% AEW (pH 8, 10 min) with a biomass concentration of 2 g/l. The initial biomass concentration and medium pH had significant influences on the flocculation activity of AEW. A viability test of flocculated microalgal cells was conducted using Evans blue stain, and the cells appeared intact. Furthermore, the growth rate of Tetraselmis sp. in recycled flocculation medium was similar to the growth rate in fresh F/2 medium. Our results suggested that AEW flocculation could be a very useful and affordable methodology for fresh biomass harvesting with environmentally friendly easy operation in part of the algal biofuel production process.

Предложено новое объяснение линейного роста плотности культур микроводорослей. Получены уравнения, описывающие зависимость коэффициента поглощения света и удельной скорости синтеза биомассы от концентрации хлорофилла а. Рассчитан удельный коэффициент экстинкции для культуры Tetraselmis viridis, который составил 0,008 мг · м-2 хлорофилла а.

Phytoplankton are important sources of dietary fatty acids (FAs) for higher trophic levels, yet FA composition varies among phytoplankton taxa, and under different growth conditions. Changes in the environment that lead to shifts in the composition of phytoplankton communities may thus alter FA supply in marine food chains. Reproductive processes in free-spawning marine invertebrates, which provision eggs with lipid to fuel early embryonic development, are particularly impacted by FA composition of the diet. In order to explore the effects of taxonomic changes in the source of phytodetrital food resources on invertebrate consumers, we conducted captive feeding experiments to examine differences in reproductive fitness of deposit-feeding sea cucumbers ( Parastichopus californicus ) fed two different algal diets. Body- and egg-condition variables were measured in females that were fed detritus of either the green alga Tetraselmis sp. or the diatom Thalassiosira sp., which differ in nutritional and FA composition. Subsequent timing of development and survival were recorded for pre- and post-feeding larval stages. FA analyses were conducted on feeds, spawned gonads, and eggs to identify specific FAs allocated to reproduction. Females that were fed Tetraselmis sp. had higher fecundity, but showed reduced larval survival relative to females that were fed the diatom Thalassiosira sp. Similar rates of larval development were recorded in both treatments. Significant differences were observed in the abundance of 20:5ɷ3 (EPA), 20:4ɷ4 (ARA), 22:3ɷ6 (DHA), 12:0, 16:0, and 18:0 FAs in eggs and gonads from females fed the two diets. Diet-related variation in fecundity and egg quality could directly affect recruitment success in P. californicus , and suggests that reproductive strategies may be altered under different environmental conditions. If feeding conditions are favorable to planktotrophic larvae, then producing a larger number of eggs with lower energy density (such as under Tetraselmis -fed treatments) may be acceptable, whereas different conditions may favor maternal investment in a smaller number of better-provisioned eggs (such as in Thalassiosira- fed treatments).

Variable fluorescence fluorometry, an analytical approach that estimates the fluorescence yield of chlorophyll a ( F 0 , a proximal measure of algal concentration) and photochemical yield ( F V / F M , an indicator of the physiological status of algae) was evaluated as a means to rapidly assess photoautotrophs. Specifically, it was used to gauge the efficacy of ballast water treatment designed to reduce the transport and delivery of potentially invasive organisms. A phytoflagellate, Tetraselmis spp. (10–12 μm) and mixed communities of ambient protists were examined in both laboratory experiments and large-scale field trials simulating 5-d hold times in mock ballast tanks. In laboratory incubations, ambient organisms held in the dark exhibited declining F 0 and F V / F M measurements relative to organisms held under lighted conditions. In field experiments, increases and decreases in F 0 and F V / F M over the tank hold time corresponded to those of microscope counts of organisms in two of three trials. In the third trial, concentrations of organisms ≥ 10 and F 0 and F V / F M decreased. Rapid and sensitive, variable fluorescence fluorometry is appropriate for detecting changes in organism concentrations and physiological status in samples dominated by microalgae. Changes in the heterotrophic community, which may become more prevalent in light-limited ballast tanks, would not be detected via variable fluorescence fluorometry, however.

Lipids in microalgae are energy-rich compounds and considered as an attractive feedstock for biodiesel production. To redirect carbon flux from competing pathways to the fatty acid synthesis pathway of Tetraselmis sp., we used three types of chemical inhibitors that can block the starch synthesis pathway or photorespiration, under nitrogen-sufficient and nitrogen-deficient conditions. The starch synthesis pathway in chloroplasts and the cytosol can be inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 1,2-cyclohexane diamine tetraacetic acid (CDTA), respectively. Degradation of glycine into ammonia during photorespiration was blocked by aminooxyacetate (AOA) to maintain biomass concentration. Inhibition of starch synthesis pathways in the cytosol by CDTA increased fatty acid productivity by 27% under nitrogen deficiency, whereas the blocking of photorespiration in mitochondria by AOA was increased by 35% under nitrogen-sufficient conditions. The results of this study indicate that blocking starch or photorespiration pathways may redirect the carbon flux to fatty acid synthesis.

The nutritional value of Pseudodiaptomus annandalie and its suitability as feed to milkfish larvae were determined. Pure isolates of P. annandalie was subjected to feeding in four different microalgal species (Chlorella sp., Chaetoceros calcitrans, Isochrysis galbana and Tetraselmis chuii) for 15 days of culture. Lipid extraction was done using Bligh and Dyer method and analyzed in a gas chromatograph for fatty acid profile. Results were analyzed using univariate ANOVA (p.0.05) and subsequent Tukey tests. Results of the first experiment showed that the number of fatty acids in P. annandalie varied significantly at different microalgal diets. DHA/EPA ratio was highest in Chaetoceros calcitrans (4.91%). This suggest that Chaetoceros calcitrans is the best microalgal food for P. annandalie because it promotes high DHA/EPA ratio in its fatty acid profile which is an important requirement for fish larvae. When live P. annandalie together with other natural foods were tested, results showed that treatment fed live copepods had significantly (p

International audience; The aim of this study is to predict Tetraselmis cells growth-kinetic and to induce the synthesis of bioactive compounds (chlorophylls, carotenoids and starch) with high potential for biotechnological applications. Using the statistical criteria, the Baranyi-Roberts model has been selected to estimate the microalgae growth-kinetic values. The simultaneous effects of salinity, light intensity and pH of culture medium were investigated to maximize the production of total chlorophylls, carotenoids and starch. The optimal culture conditions for the production of these compounds were found using Box-Behnken Design. Results have shown that total chlorophyll and carotenoids were attained 21.6mg·g-1DW and 0.042mg·g-1DW, respectively. In addition, the highest starch content of 0.624g·g-1DW has been obtained at neutral pH with high irradiance (182μmolphotonsm-2 s-1) and low salinity (20). A highly correlation (R2 = 0.884) has been found between the gravimetric and flow cytometric measurements of chlorophyll content.

Lipid extraction is a critical step in the downstream processing of biodiesel production from microalgae. Solvent extraction using mixtures of non-polar and polar solvents is one of the most well-known processes for this purpose. Hexane is the most common solvent of choice for large-scale lipid extractions due to its technical and economic advantages, especially its high selectivity toward lipids and low cost. In this study, extractions using mixtures of hexane and polar solvents were evaluated for their performance in order to develop a more efficient method for large-scale lipid extraction from microalgae. The combination of hexane and methanol resulted in the highest fatty acid methyl ester (FAME) yield for lipids from Tetraselmis sp. The effects of extraction conditions, including proportions of methanol to hexane, ratios of total solvent volume to dry biomass, and extraction time, on extraction yields were evaluated to determine optimum conditions providing higher lipid and FAME yields. The optimal conditions were as follows: proportion of hexane to methanol of 1:1, ratio of total solvent volume to dry biomass of 10 mL/g, and extraction time of 120 min. Finally, the selected solvent mixture and optimal conditions were applied to larger scale extraction experiments with scale-up factors of 10, 50, and 100. FAME yields of large-scale extractions were almost completely consistent with increasing scale-up factors. The results of this study suggest that a hexane and methanol mixture is a promising solvent for large-scale lipid extraction from microalgae.

In this study, hypersaline media were used for ocean cultivation of the marine microalga Tetraselmis sp. KCTC12432BP for enhanced biomass and fatty acid (FA) productivity. Hypersaline media (55, 80, and 105 PSU) were prepared without sterilization by addition of NaCl to seawater obtained from Incheon, Korea. The highest biomass productivity was obtained at 55 PSU (0.16 g L−1 day−1) followed by 80 PSU (0.15 g L−1 day−1). Although the specific growth rate of Tetraselmis decreased at salinities higher than 55 PSU, prevention of contamination led to higher biomass productivity at 80 PSU than at 30 PSU (0.03 g L−1 day−1). FA content of algal biomass increased as salinity increased to 80 PSU, above which it declined, and FA productivity was highest at 80 PSU. Ocean cultivation of Tetraselmis was performed using 50-L tubular module photobioreactors and 2.5-kL square basic ponds, closed- and open-type ocean culture systems, respectively. Culturing microalgae in hypersaline medium (80 PSU) improved biomass productivities by 89 and 152% in closed and open cultures, respectively, compared with cultures with regular salinity. FA productivity was greatly improved by 369% in the closed cultures. The efficacy of salinity shift and N-deficiency to enhance FA productivity was also investigated. Lowering salinity to 30 PSU with N-starvation following cultivation at 80 PSU improved FA productivity by 19% in comparison with single-stage culture without N-deficiency at 30 PSU. The results show that salinity manipulation could be an effective strategy to improve biomass and FA productivity in ocean cultivation of Tetraselmis sp.

Open ponds are the preferred cultivation system for large-scale microalgal biomass production. To be more sustainable, commercial scale biomass production should rely on seawater, as freshwater is a limiting resource, especially in places with high irradiance. If seawater is used for both pond fill and evaporative volume makeup, salinity of the growth media will rise over time. It is not possible for any species to achieve optimum growth over the whole saline spectrum (from seawater salinity level up to salt saturation state). In this study, we investigated the effects of gradual salinity increase (between 35 and 233 ppt) on biomass productivity and biochemical composition (lipid and carbohydrate) of six marine, two halotolerant, and a halophilic microalgae. A gradual and slow stepped salinity increase was found to expand the salinity tolerance range of tested species. A gradual reduction in biomass productivity and maximum photochemical efficiency was observed as a consequence of increased salinity in all tested species. Among the marine microalgae, Tetraselmis showed highest biomass productivity (32 mg L−1 day−1) with widest salinity tolerance range (35 to 109 ppt). Halotolerant Amphora and Navicula were able to grow from 35 ppt to 129 ppt salinity. Halophilic Dunaliella was the only species capable of growing between 35 and 233 ppt and showed highest lipid content (56.2%) among all tested species. This study showed that it should be possible to maintain high biomass in open outdoor cultivation utilizing seawater by growing Tetraselmis, Amphora, and Dunaliella one after another as salinity increases in the cultivation system.

Brachionus plicatilis is used to feed fish and crustacean larvae in the aquaculture industry. It is well established that the type of microalgae may influence rotifer production. This experiment was conducted to determine the effect of five different locally available microalgae species at Fisheries Research Institute (FRI), Kampung Pulau Sayak, Kedah, Malaysia on the instantaneous growth rate (μ) of rotifer. Nannochloris sp., Tetraselmis sp., Isochrysis sp., Chlorella sp., and Nannochloropsis sp. were used as feed at different algae densities (0.1, 0.3, 0.7 and 1.5 × 106 cells/ml) and culture volumes (20, 70 and 210 ml). At algae densities ranging from 0.3 to 1.5 × 106 cells/ml, an average μ value of more than 0.90 per day were recorded for all algae species. However, at density of 0.1 × 106 cells/ml, only Tetraselmis sp. resulted in the significantly highest μ value compared with others (p < 0.05). In terms of volume, smaller culture volume of Tetraselmis sp. (20 ml) showed significantly higher μ compared with higher volume (70 and 210 ml cultures).

After a 1.5-year screening survey in the lagoons of Western Greece in order to isolate and culture sturdy species of microalgae for aquaculture or other value-added uses, as dictated primarily by satisfactory potential for their mass culture, five species emerged, and their growth was monitored in laboratory conditions. Amphidinium carterae, Nephroselmis sp., Tetraselmis sp. (var. red pappas), Asteromonas gracilis, and Dunaliella sp. were batch cultured using low (20 ppt), sea (40 ppt), and high salinity (50 or 60 or 100 ppt) and in combination with low (2000 lux) and high (8000 lux) intensity illumination. The results exhibited that all these species can be grown adequately in all salinities and with the best growth in terms of maximum cell density, specific growth rate (SGR), and biomass yield (g dry weight/L) at high illumination (8000 lux). The five species examined exhibited different responses in the salinities used, whereby Amphidinium clearly performs best in 20 ppt, far better than 40 ppt, and even more so than 50 ppt. Nephroselmis and Tetraselmis grow almost the same in 20 and 40 ppt and less well in 60 ppt. Asteromonas performs best in 100 ppt, although it can grow quite well in both 40 and 60 ppt. Dunaliella grows equally well in all salinities (20, 40, 60 ppt). Concerning the productivity, assessed as the maximum biomass yield at the end of the culture period, the first rank is occupied by Nephroselmis with ~3.0 g d.w./L, followed by Tetraselmis (2.0 g/L), Dunaliella (1.58 g/L), Amphidinium (1.19 g/L), and Asteromonas (0.7 g/L) with all values recorded at high light (8000 lux).

Penelitian ini membahas tentang penentuan batas laju alir yang diberikan kepada mikroalga Tetrashelmis chuii dan Spirrulina sp terhadap ketahananya dalam hal mengadsorpsi CO2 dengan konsentasi umpan CO2 yang cukup besar. Tujuan dari penelitian ini adalah menentukan batas toleransi laju alir gas umpan dengan konsentrasi CO2 konstan pada mikroalga (Tetraselmiss chuii dan Spirrulina sp) dalam fotobioreaktor. Hal ini diperlukan untuk mengkarakteristikan jenis mikroalga terhadap ketahanannya dalam menerima umpan gas yang diberikan untuk mengurangi jumlah CO2 dengan dilakukannya variasi laju alir umpan masuk fotobioreaktor yaitu 1 l/menit , 1,5 l/menit dan 2 l/menit dengan konsentrasi CO2 sebesar 33 %. Didapatkan hasil bahwa laju alir yang optimum yang dimiliki oleh mikroalga paling baik dalam penyerapan CO2 yaitu Spirrulina sp dengan kemampuan laju alir 1 l/menit dengan penyerapan sebesar 83,13 % dibanding Tetraselmis chuii dengan laju alir 1,5 l/menit dengan penyerapan sebesar 76,10 %.

Microalgae as feedstock of bioenergy, mainly biodiesel, is receiving an increased attention from scientific and industrial point of view. The selection of promising strains and optimization of the production process are essential keys to develop an economically viable project. In this context, fifty-seven strains of marine microalgae have been isolated from the Moroccan Atlantic and Mediterranean coasts. The selection of most promising strains was based on biomass productivity, lipid content and fatty acids profile. Nannochloropsis gaditana (24), Chlorella sp (67), Dunaliella tertiolecta (29) , Isochrysis sp (77), Phaeodactylium tricornutum (23) and Chaetoceros sp (63) showed the best growth rate, whereas lipid content was highest in Navicula sp (up to 63%) and Tetraselmis sp (up to 56%), Dunaliella sp (up to 50%), Nannochloropsis sp (up to.60%) and Chaetoceros sp (up to 56%). Fatty Acids Methyl Ester profiles were analyzed and most strains studied showed a high rate of PUFA’s mainly those belonging of Dunaliella , Tetraselmis , Isochrysis and Nannochlorpsis genuis. For Bacillariophyceae, despite their high content in lipids, their FAME profile was rich in PUFA’s which affects the quality of biodiesel. This study describes the microalgae screening process and demonstrates that Nannochloropsis sp, Dunaliella tertiolecta, Isochrysis sp and Tetraselmis sp are among promising species as biodiesel feedstock.

Data of this article describes growth, survival rate, water quality and hemato-biochemical indices of Nile Tilapia (Oreochromis niloticus) fry. To collect the data, the Nile Tilapia fry was reared in 30 L glass aquarium (18 fish/ tank) for 56-days under controlled environmental condition. Feed was prepared with 25 and 50% replacement of commercial fish meal with Nannochloropsis sp. and Tetraselmis sp. microalgae, while no replacement was made for control feed. Initial and final body weight of fish was recorded to find the data of growth rate; survival rate was calculated from the initial and final live individuals recorded during the experiment; physico-chemical parameters were analyzed to collect water quality data; hemato-biochemical indices were collected using hematology analyzer and photometry. The data on growth, survival rate and hemato-biochemical indices were statistically significant (p < 0.05). Therefore, these data might contribute to the selection of marine microalgae to improve the water quality during fish farming which could enhance the growth and survivability of fish. In addition, the data of hemato-biochemical indices represent that feeding selected marine microalgae might result in the production of healthy and disease-free fish.

Unwanted proliferation of and adhesion by microalgae, as involved in fouling and species invasion, are important problems across many maritime operations and coastal industrial activities. The algicidal mechanisms of ultraviolet light-emitting diodes (UV-LEDs) and the synergistic algicidal effects between UV-LEDs and chlorine treatments in seawater were investigated in this study. Tetraselmis sp. was employed as the challenge organism. Five UV wavelengths (265, 280, 285, 300 and 315 nm) and three chlorine dosages (0.6, 0.8 and 1 mg L−1) were examined in a factorial experiment to optimize the disinfection performance achieved by combined UV-LED/chlorine treatments in seawater. Overall, the combined treatments showed a more effective inactivation of the microalgae than did the single treatments. Treatment with UV285 combined with 0.8 mg L−1 chlorine resulted in 3.12-log inactivation at 100 mJ cm−2 (i.e. 2.34 Einsteins L-1, 67 s). This optimal combination showed a higher inactivation rate constant and lower energy consumption (EE,2) than did the other treatments. The contribution of UV-LEDs, chlorine and hydroxyl radical (·OH) in the inactivation of Tetraselmis sp. by the combined UV-LED/chlorine disinfection process was investigated to illustrate the mechanism of this synergistic process, the results indicated that ·OH generated by photolysis were not the only contributors to the inactivation of the microalgae. Although a UV300/chlorine treatment demonstrated the highest chlorine photolysis rate, the inactivation constant of this treatment was lower than that of UV285/chlorine. These results demonstrated a synergistic algicidal effect of the combined disinfection system caused by exposure to the 285 nm UV-LED and low dosages of chlorine, which could provide an important basis for further developments and possibly industrial applications in the future.

In this study, an efficient, simple and eco-friendly biological method, immobilized Tetraselmis chuii beads (TetraBeads) were tested for its efficacy in maintaining water quality to improve the survival and growth of Penaeus monodon postlarvae. Results showed that the tanks, treated with Tetrabeads, were able to significantly (p

This study investigates the capability of Tetraselmis sp. for treating mariculture wastewater in a 70-L high-rate algal pond and determines the feasibility of using the resulting biomass. The culture medium contained 45 mg L–1 nitrates, 10 mg L–1 nitrites, 30 mg L–1 ammonium, 17 mg L–1 orthophosphates and 270 mg O2 L–1 of dissolved organic matter as chemical oxygen demand (COD). The culture was kept under a 12 h:12 h light:darkness photoperiod using a photosynthetically active photon flux density of 1500 μmol m–2 s–1, and a temperature of 23 ± 2 °C. A 4-cycle growth semicontinuous culture was used obtaining on average 1.19 g L−1 dry biomass, with lipid content of 62.16 mg g−1. In the first batch culture cycle, 11.4 % of highly non-saturated fatty acids were obtained, and a significant decrease thereof was observed in subsequent batch culture cycles. Nutrient removals were 95.5 ± 0.4 % total nitrogen, 94.4 ± 0.5 % ortho-phosphates and 61.4 ± 3.9 % COD. These results show the feasibility of mariculture wastewater treatment using the studied microalga, with the advantage of producing biomass containing accumulated lipids and usable as food for mariculture species. Thus, it may be possible to reduce the cost of wastewater treatment and of culturing marine species.

The rich nutritional profile of microalgae biomass has made it a promising clean label food ingredient that has the potential to fortify incorporated food with simultaneous modification of the structural properties. This work investigated the effect of high pressure homogenization (HPH) at 300, 600, and 900 bar on the microstructural and rheological properties of four microalgal suspensions, namely, Arthospira platensis, Isochrysis sp., Nannochloropsis sp., and Tetraselmis sp. HPH treatment resulted in the disintegration of microalgal cells, which altered the cell morphology, particle size, and rheological properties. A. platensis, Isochrysis sp., and Tetraselmis sp. showed a linear HPH intensity-dependent cell disintegration as evidenced by an increase in viscosity of the suspensions. While A. platensis exhibited the most pronounced effect of HPH treatment, Nannochloropsis sp. showed a minimal response that was attributable to its strong cell walls. The significant interspecies differences in the colloidal properties of the HPH-treated microagal suspensions coincided with the proportion of various nutrients where the fluctuation of lipids (between 8% and 17%) and proteins (between 10% and 57%) affected hydrophilic/hydrophobic interactions between the macromolecules. The findings demonstrate that HPH can be used to tailor microalgae biomass for specific food applications as potential structuring ingredients.

Microalgae constitute an underexploited feed resource for ruminant nutrition. The unique digestive tract of ruminants makes them best suited to utilise complex polysaccharides and non-protein nitrogen of eukaryotic microalgae, though contrasting effects on rumen fermentation have been reported. The current study aimed to assess the effects of microalgae species, inclusion level and basal substrates on in vitro rumen fermentation parameters. To this end, haylage and maize silage were supplemented with 2.5, 5 and 10% (w/w, dry matter basis) of Chlorella vulgaris, Nannochloropsis oceanica and Tetraselmis sp. and incubated for 24-h with rumen inocula non-adapted to microalgae. No significant interaction was observed among basal substrate, microalgae species and inclusion level for any of the parameters evaluated. Substrate and microalgae species interaction affected most fermentation parameters. The lowest gas and methane productions and yields, total volatile fatty acids (VFA) production and concentrations of acetic, butyric and most minor VFA observed when C. vulgaris was incubated with haylage suggest that rumen fermentation was inhibited to a greater extent by this microalgae, probably reflecting a low availability of rapidly fermentable carbohydrates due to differences in cell wall structure and composition. However, the opposite was observed when C. vulgaris was incubated with maize silage, suggesting an improvement in the synchrony between fermentable energy and degradable nitrogen. Microalgae species and inclusion level interaction mainly affected methanogenesis. The lowest methane yield with N. oceanica at 10% may be explained by its high content of polyunsaturated fatty acids. The interaction between basal substrate and microalgae inclusion level did not affect any parameter. Overall, the effects of the interactions between substrate and microalgae species and microalgae species and inclusion level, underpin the importance of identifying optimal microalgae species and inclusion levels according to the basal diet fed to ruminants.

Hydrothermal liquefaction is a promising technology for microalgae-based biofuel production. However, hydrothermal liquefaction’s aqueous wastes have little established reuse, and contain significant fractions of toxic ammoniacal nitrogen. Careful reuse of this waste can assure microalgae-based biofuels are produced with less environmental impact and larger energy efficiency. Microbial electrolysis cells were investigated to valorize this waste product by converting the leftover organics into hydrogen and remove ammonia. Waste hydrothermal liquefaction aqueous phase from two microalgal strains, Tetraselmis sp. and Chlorella sp. were used as feedstocks for hydrogen production in microbial electrolysis cells. Chlorella and Tetraselmis aqueous phase-fed microbial electrolysis cells reach an average current density of 5.1 ± 0.19 A/m2 and 3.8 ± 0.08 A/m2. Compound removal rates and mass removal percentages were also investigated for each feedstock. Acetic acid, propionic acid, ethanol, and glycerol were effectively removed from the aqueous byproduct. Further, microbial electrolysis cells separated up to 34.3% of ammoniacal nitrogen present in the aqueous phase. Charge transfer analysis indicated that proton transfer, not ammonium transfer, contributed to the majority of the hydrogen production in the cathode. Finally, the microbial electrolysis cell effluent was reused to grow the same microalgal strains, leading to the development of a circular biofuel production system. Microalgae regrowth studies using microbial electrolysis cell effluent showed nearly complete removal of total organic carbon, but significantly less removal of total nitrogen. Tetraselmis sp. growth occurred with the Tetraselmis-derived MEC effluent, however, the control medium without effluent produced the most growth. These findings support the possibility of a circular biofuel framework using MECs, but additional constraints, including the removal of inorganic contaminants, are necessary to realize the circular processes.

The growth performance and mass production of Eurycercus beringi sp. nov., comes under cladocera isolated from Adyar creek, Chennai fed with different diets includes Chlorella sp, Nannochloropsis sp, Chaetoceros sp, Thalassiosira sp, Tetraselmis sp, Dunaliella sp and Isochrysis sp, rice bran and baker’s yeast as monospecific and mixed diets (1:1) have been investigated. The species reproduce parthenogenetically attained a size range of 300- 1098 μ m and tolerate salinity range of 3–35‰ with fecundity range of 2–7 numbers with minimum maturation period of 3–6 days depending on quality of feed with minimum aeration. Salinity found to play a significant role in survival with maximum survival at 25 ‰. There is a significant difference (p × 105 cells/ml) i.e. 8 and 7 number of individual/broodstock respectively where as the species attained maturity within 3 days in the treatment fed with Chlorella sp followed by combination of Chlorella and Chaetoceros sp (4 days) and Chlorella and Thalassiosira sp as monospecific diet (4 days each). Mass culture of E. beringi sp. nov. at 100 nos/L was carried out using microalgae, rice bran and baker’s yeast revealed a maximum density 5887 ± 109 nos/L recorded at 30 ‰ within 7 days when fed with mixed diets of Chlorella and Nannochloropsis sp followed by rice bran with baker’s yeast (4586 ± 167 nos/L). Partial replacement of Artemia nauplii with E. beringi sp. nov. (1:1) with highest survival (65 ± 3 %) during early post larval stages of Penaeus indicus revealed its potential to use as live feed in larval rearing. The study highlighted the scope of E. beringi sp. nov. to use as live feed during the larval rearing of brackishwater finfish and shellfishes.

Marine green microalgae are a sustainable source of high-quality protein. However, due to their green pigmentation and composition of volatiles, their incorporation into food products is a challenge. Incorporation of cell-wall disrupted Tetraselmis chuii (Tc) into bread (0, 4, 8, 12 and 16% wheat flour substitution) affected dough rheology and bread quality negatively. These effects were more pronounced at addition levels necessary for a EFSA nutrition claim on protein enrichment (12 and 16%). Treatment of Tc with ethanol not only removed much of the green pigmentation and volatiles, but also reduced the negative impact on dough rheology and bread quality. Doughs prepared with ethanol treated Tc (TcEt) showed a clear improvement in dough rheology evident as increased dough-stability-time (DST), resistance to extension (Rmax) and elastic-recovery-compliance (Je) particularly at substitution levels >4%. This was accompanied by an increase in bread quality e.g. at 12% substitution level specific volume increased from 2.1 to 2.69 mL/g, crumb firmness decreased from 1358 to 297 g and slice brightness increased from 25.2 to 49.0. Ethanol treatment of algae may be a feasible strategy to address the sensory and structural challenges that hinder incorporation of algae into foods at levels that can potentially confer nutritional benefits.

Bioaccumulation of radiocaesium in many marine organisms occurs through complex trophic transfer mechanisms. The present study addresses the trophic transfer of 134 Cs in the widely distributed marine bivalve, the Manila clam Ruditapes philippinarum , by experimentally determining the assimilation efficiency (AE) and the specific role of food quality or diet on the AE in this marine invertebrate. Pulse-chase feeding experiments were carried out on this clam using the phytoplankton species Tetraselmis chuii , Phaeodactylum tricornutum and Isochrysis galbana . Depuration kinetics of 134 Cs over 21 days were analysed using a two-component exponential model. Observed assimilation efficiencies were consistently less than 10% but slightly varied among individuals fed on the three different phytoplankton species diets ( T. chuii : AE = 8.4 ± 0.6%; P. tricornutum : AE = 9.8 ± 0.5%; I. galbana : AE = 5.3 ± 0.6%), although no statistical differences were observed. Comparing results from these experiments with existing data from the literature on the same species exposed to caesium through seawater, it appears that trophic transfer processes are the main accumulation pathway, contributing up to 96% of the global 134 Cs bioaccumulation in this bivalve species.