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We evaluated the accumulation of okadaic acid (OA), a diarrhetic toxin, and the antioxidant responses in the marine annelid Laeonereis acuta exposed to the benthic toxigenic dinoflagellate Prorocentrum cf. lima. Nontoxic Tetraselmis sp. was used as a control diet. Living cells of the two algae were supplied as food to animals kept in agar medium for 72 h. To assess the significance of the observed effects, our experimental design treated the algal species (diet), algal cell densities, and exposure time as fixed factors. Responses of the organisms were assessed through oxidative stress biomarkers (glutathione-S-transferase [GST], catalase [CAT], reduced glutathione [GSH] and lipid peroxidation [LPO]). Toxin accumulation was measured by LC-MS/MS in whole-body homogenates after 12, 24 and 72 h of exposure. Worms exposed to the toxigenic dinoflagellate gradually accumulated OA, with toxin levels directly related to the cell density of Prorocentrum cf. lima. Worms fed with Prorocentrum cf. lima exhibited decreased CAT activity, increased LPO levels – both interactively affected by algal species and time – and decreased GSH levels, which were interactively affected by algal species and cell density. Higher LPO levels, along with the inhibition of CAT and GSH, clearly indicated an oxidative stress situation in worms exposed to the toxigenic dinoflagellate. Laeonereis acuta accumulated moderate OA levels and may act as a vector of OA to food webs in estuarine areas under high Prorocentrum cf. lima abundance.

CDs are carbon fluorescent nanomaterials that have gained significant attention in recent years owing to their unique properties. In this work, we utilized a simple solution to produce CDs with func-tionalized amino groups via a one-step carbonization from a chitosan precursor. This simultaneous approach does not use special reagent for either the formation step or the amino-functionalization step of CDs. The as-prepared amino-functionalized CDs that possesses expected characteristics, such as nano-size distribution, monodispersible, high blue light emission, high absolute quantum yield of 5.52%, and functionalized amino groups on the surface. Furthermore, this work demonstrated the low cytotoxicity and high biocompatibility of the CDs, through the improvements in the astaxanthin production of alga Tetraselmis sp. (more than doubled (up to 0.044 mg/L), relative to the control). Thus, as-prepared CDs have promising properties not only for applications in bioimaging, drug delivery or sensors, but also as promoter in algal biorefinery

The aim of this study was to evaluate the growth-promoting effects of the combination of magnesium aminoclay (MgAC) and amino-functionalized carbon dots (N(CD)s) on Tetraselmis sp. cultures with an emphasis on N(CD)s. To that end, simply sol-gel-synthesized MgAC and one-pot carbonization-synthesized N(CD)s were utilized. The as-prepared N(CD)s possessed the expected amino-functional groups, exhibited strong blue emission with bright luminescence, and showed a quantum yield (QY) of 5.69%. The maximum specific growth rate and biomass productivity were achieved with the combination of 0.1 g L−1 MgAC and 40 μg mL−1 N(CD)s, which afforded improvements in lipid and protein accumulation relative to the control, whereas carbohydrate accumulation slightly decreased. At low concentrations (0.1 g L−1), MgAC demonstrated growth stimulation. The N(CD) addition to the MgAC-containing medium further supported the Tetraselmis sp. cultures in counteracting the effects of UV radiation and in improving photosynthesis activity. In these ways, increased growth and biomass productivity under UV irradiation and enhanced pigment contents under the light-irradiance condition were obtained. Therefore, use of the MgAC-N(CD) combination as a culture-medium supplement is a promising method for microalgae biorefinery applications.

A Tetraselmis sp. was selected for its antioxidant activity owing to its high lipid peroxidation inhibition capacity. With the aim to monitor culture conditions to improve antioxidant activity, effects of CO2-induced acidification on Tetraselmis growth, elemental composition, photosynthetic parameters and antioxidant activity were determined. Two pH values were tested (6.5 and 8.5) in batch and continuous cultures in photobioreactors. Acidification enhanced cell growth under both culture methods. However, the microalgae physiological state was healthier at pH 8.5 than at pH 6.5. Indeed, photosynthetic parameters measured with pulse amplitude modulated (PAM) fluorometry showed a decrease in the photosystem II (PSII) efficiency at pH 6.5 in batch culture. Yet, with the exception of the PSII recovering capacity, photosynthetic parameters were similar in continuous culture at both pH. These results suggest that lowering pH through CO2-induced acidification may induce a lower conversion of light to chemical energy especially when coupled with N-limitation and/or under un-balanced culture conditions. The highest antioxidant activity was measured in continuous culture at pH 6.5 with an IC50 of 3.44 ± 0.6 μg mL−1, which is close to the IC50 of reference compounds (trolox and α-tocopherol). In addition, the principal component analysis revealed a strong link between the antioxidant activity and the culture method, the photophysiological state and the nitrogen cell quota and C:N ratio of Tetraselmis sp.. These results highlight Tetraselmis sp. as a species of interest for natural antioxidant production and the potential of PAM fluorometry to monitor culture for production of biomass with a high antioxidant activity.

The production of biocrude with and without sodium hydroxide catalyst (Na2CO3) through hydrothermal liquefaction of Tetraselmis sp. microalga at different organic solids loading was investigated. The HTL experimental study was conducted at reaction temperatures of 310oC, 330oC, 350oC and 370oC at 5 min fixed reaction time with organic solids loading of 10%w/w, 15%w/w, 20%w/w, 25%w/w, 30%w/w, and at 40%w/w. The results of the study showed that organic solids loading above 20%w/w had no substantial changes on biocrude yield. The catalyst had very little effect on the yield of biocrude but substantially enhanced its quality when compared with non-catalysed reactions. Although, Na2CO3 catalyst may be used for HTL of Tetraselmi sp. in laboratory-scale studies, it is highly unnecessary for commercial-scale. Thus potentially reducing the production cost in future commercialization of HTL-alga-biorefinery. Keywords: Biocrude, Na2CO3 catalyst, hydrothermal liquefaction, Microalga, organic solids loading

Chromosome visualization is a technique used in many modern applications such as classification, in situ hybridization and genetic improvements, etc. Algal biotechnology grew steadily into an important global industry. Dunaliella salina (Teodoresco, 1905) is a model microalgae having tremendous potential for production of carotenoids for commercial use. The chromosomal size of microalgae is very small, and techniques for karyotype analysis are still unclear. In this work, it tried to simplify the techniques and establish a detailed step-by-step protocol using Dunaliella salina as a model and proved the technique in Tetraselmis chuii (Stein, 1878) which can be reproducible. The most important points were considered in the techniques as metaphase resting, fixation, dehydration and rehydration, hydrolysis and preparation of chromosomes for microscopic observations. During standardization, various concentration and duration of colchicine treatment were tested for metaphase arrest, replaced ethanol for methanol during fixation and dehydration, used a rehydration solution before hydrolysis and observed acid, base and enzymes impact on partial hydrolysis process of the cells. Colchicine treatment was found to be species dependent, and optimum concentration was 0.1% for 6 h (h) for Dunaliella salina, and methanol proved better to dehydrate for the preservation of algal cells. The low 500 mM concentration of HCl, 30 mM KOH and 5% enzyme proved to be suitable for the hydrolysis process for algal chromosome visualization. The technique permits clear visualization and counting of the smallest chromosome from unicellular algae. This technique described detail step by step without ambiguity and steps can be adapted on a species-specific manner.

The investigation of Titanium dioxide (TiO2) nanoparticles on the thermal characteristic ofTetraselmis chuii(T.Chuii) microalgae during combustion process has been carried out through a thermogravimetric (TG) analyzer.T.Chuiimicroalgae samples were cultured within 8 days at BBPBAP Jepara, Central Java, Indonesia. The microalgae sediment was dried at 80°C for 24 hours then was powdered by means of a mortar. Thereafter, the dried powder of microalgae was filtered with a size of 60 mesh. Titanium dioxide (TiO2) nanoparticles were used as catalysts with the particle size of < 25 nm; these were obtained from Singapore’s Sigma Aldrich. Amount of 0.03 mg of TiO2and 10 mg ofT.Chuiimicroalgae were mixed mechanically using a mortar to guarantee the homogeneous blend, and then this sample was heated up in the oven for 14 hours at 80°C. The TG experiment was performed at a temperature range 25 to 900°C with atmospheric air at a flow rate of 50 mL/min and a heating rate of 15 °C/min. Differential method ofArrheniusis applied to evaluate kinetic parameters, including reaction order (n), activation energy (Ea), and pre-exponential factor (log A) that were 0.9; 74,191 kJ/mol and 6.38 min-1for the stage II and 0.87; 118.47 kJ/mol and 7.29 min-1for stage V.

This study aims to analyze the thermal characteristics ofTetraselmis chuii(T.Chuii) microalgae in the presence of TiO2(Titanium dioxide). The experiment was carried out on thermal analyzer equipment under inert condition. The blended sample has a mass ratio of microalgae and TiO2that was 10:0.03 (wt%). The results of the thermal analysis show that the addition of TiO2can change the temperature characteristics during the reaction process. The Coats-Redfern method is applied to calculate activation energy (Ea) resulted in the value of the blended fuel in the second stage that was 56.9 kJ/mol lower than that of pure microalgae that was 70.68 kJ/mol and conversely in the third stage the value of activation energy for blended fuel was 264.57 kJ/mol higher than pure microalgae that was 223.25 kJ/mol. Overall results pointed out that TiO2had a significant impact on the thermal characteristic ofTetraselmis chuiiduring the pyrolysis process.

Larval rearing techniques with suitable nursery feed should be prioritized for better survival and growth. We evaluate the potential use of Cyclops abyssorum divergens as a natural live food candidate instead of the costly traditional Artemia franciscana in the feeding strategy for Dicentrarchus labrax larvae. C. abyssorum divergens and A. franciscana were enriched with mixed valuable algae strains (Isochrysis galbana, Tetraselmis chuii, Chlorella marina and Nannochloropsis oculata) that were used in equal biomass proportions (1:1:1:1) on dry weight basis. Amino acids and fatty acid profiles were found to be highly significantly different in enriched C. abyssorum divergens (EC) compared to enriched A. franciscana (EA). The findings also revealed compensated deficiency in some amino acids such as histidine, isoleucine, and methionine in EC and also increased levels of total essential amino acids (EAA) in EC by 8.2 % more than that of EA. Further metabolizing of palmitic acid (C16:0) and bio-conversion of α- linolenic acid, ALA (C18:3 n-3) to high accumulation of DHA fatty acid lead to higher PUFAs contents in EC and lower levels in EA. Specific growth rates (SGR) and survival percentages (S %) of D. labrax were higher in larvae fed with EC compared to the lower values in EA. Moreover, analyzing final carcass composition revealed increased levels of DHA fatty acid attaining DHA/EPA ratio in fish-fed EC of 2.95 % (>1) compared to 0.90 % (

The awareness of harmful effects of synthetic compounds and an inclination towards the usage of natural products have led to the exploitation of microalgae as a source of natural colors. Because of their health benefits, algal pigments have massive commercial value as natural colorants in the nutraceutical, cosmetics, and pharmaceutical industries. One of the important natural sources of microalgae are antioxidants, bioactive components: such as polyunsaturated fatty acids, β-carotene, sulfated polysaccharides and sterols. However, these antioxidant-rich fractions and carotenoids possess low storage stability and exhibit high sensitivity to light, heat, and oxygen. During the extraction process, there is some loss of required materials, and also, chances of the contamination from toxic solvents. There are few reports on algal-extract encapsulation and algal biomass encapsulation, and only a few types of wall materials that can show better stability, shelf life, and controlled release have been investigated. In this work, we investigated micro-encapsulation of the fresh algal biomass of Tetraselmis chuii and studied the effect of the wall material and the processing conditions of the spray dryer on the preservation of β-carotene and antioxidant compounds. Our studies revealed that a native species of Tetraselmis from Mexico, which is an important aquaculture feed, produce a considerable amount of β-carotene as much as 1.3% of its biomass. We found preservation of 80–92% of beta-carotene and 46–81% phenolic-compounds in freshly microencapsulated microalgae even after three months of storage in dark condition at 25 °C, maltodextrin at 130 °C was found the best wall material. This alga is suitable for use in aquaculture and food industry because fresh microalgae can be microencapsulated without loss of its nutritional values, and it is easier to handle and transport. This can serve as a functional food with better preservation of its antioxidant value and can be processed without any toxic solvent component.

Data on growth, productivity, pigments and proximate composition of the four different indigenous marine microalgae (isolated from Cox's Bazar Coast) were collected to compare the growth performance, pigments and nutritional composition. Chlorella sp., Nannochloropsis sp., Tetraselmis sp. and Chaetoceros sp. are the four different marine microalgae. Growth curve was determined as the prerequisite to identify the stationary phase for each of the isolated microalgae. Data on growth curves were collected in terms of cell density and optical density to observe the growth rates and division per day. Isolated species were mass cultured in commercial culture medium. When the culture reached at stationary phase, microalgae were extracted to determine productivity, pigments, and proximate composition. The data of productivity (volumetric, areal and lipid productivity), pigments (Chlorophyll a, b, c, carotenoids, and phycobiliproteins), and proximate composition (protein, lipid, and carbohydrate) were significantly (p < 0.05) different among the four different microalgae. Therefore, this data will contribute to the selection of potential microalgae species through proper characterization for vast industrializations.

Producing biocrude from hydrothermal liquefaction (HTL) of microalgae has the potential to complement fossil fuels, while simultaneously reducing greenhouse gas emissions. However, biocrude recovery from the HTL reaction product has been a concern. In this study, analysis of yields and property of biocrude recovered with and without using dichloromethane (DCM) organic solvent was investigated. The HTL experiment were performed at reaction temperature of 350oC and 20 min reaction time using 16 w/w % solids each of Spirulina sp. and Tetraselmis sp. Data obtained showed that use of DCM favours maximum biocrude yield but of lower quality when compared with DCM-free biocrude. Biocrude yield of 58wt% was obtained from Tetraselmis sp. and 48wt% from Spirulina sp. when DCM was used. About 38 and 40wt% biocrude yields were derived with DCM-free recovery process. Higher carbon content, energy dense, and lower heteroatoms content constitutes biocrude recovered without DCM treatment, which is in contrast to the biocrude recovered with DCM. In addition, an average energy input of 13MJ/kg is required to produce unit biocrude, with an additional energy input ~0.5MJ/kg to evaporate DCM when used in biocrude recovery.Keywords— Bio-energy, Hydrothermal liquefaction, Microalgae, Organic solvent, Separation method

[Purpose] This study investigated the effects of marine phytoplankton supplementation (Oceanix®, Tetraselmis chuii ) on 1) maximal isometric strength and immune function in healthy humans following a one-week high-intensity resistance-training program and 2) the proinflammatory cytokine response to exercise in a rat model. [Methods] In the human trial, 22 healthy male and female participants were randomly divided into marine phytoplankton and placebo groups. Following baseline testing, participants underwent a 14-day supplement loading phase before completing five consecutive days of intense resistance training. In the rat model, rats were randomly divided into four groups (n=7 per condi tion): (i) control, (ii) exercise, (iii) exercise + marine phy toplankton (2.55 mg/kg/day), or (iv) exercise + marine phytoplankton (5.1 mg/kg/day). Rats in the exercising groups performed treadmill exercise 5 days per week for 6 weeks. [Results] In the human model, marine phytoplankton prevented significant declines in the isometric peak rate of force development compared to placebo. Additional ly, salivary immunoglobulin A concentration was signifi cantly lower following the resistance training protocol in the placebo group but not in the marine phytoplankton group. Marine phytoplankton in exercising rats de creased intramuscular levels and serum concentrations of tumor necrosis factor-alpha (TNF-α) and interleu kin-1 beta (IL-1β) and intramuscular concentrations of malondialdehyde. [Conclusion] Marine phytoplankton prevented dec rements in indices of functional exercise recovery and immune function. Mechanistically, these outcomes could be prompted by modulating the oxidative stress and proinflammatory cytokine response to exercise.

Estuarine ecosystems near mega-cities are sinks of anthropogenic endocrine disrupting chemicals (EDCs). As the most important primary producer, indigenous microalgae and their secreted extracellular polymeric substances (EPSs) might interact with EDCs and contribute to their fate and risk. Tetraselmis sp. is a representative model of estuarine microalga, for which EDC toxicity and its effects on EPS synthesis have rarely been studied. Through microalgal isolation, algal cell growth tests, EDC removal and the characterization of related EPS profiles, the present work intends to clarify the comparative responses of Tetraselmis sp. to nonylphenol (NP), bisphenol A (BPA) and 17α-ethinylestradiol (EE2). The results showed that the half inhibitory concentration on cell growth was 0.190–0.313 mg/dm3 for NP, which was one order of magnitude lower than the comparable values for BPA and EE2 at 2.072–3.254 mg/dm3. Regarding chlorophyll, NP induced its degradation, EE2 led to its decreased production, and BPA had no obvious effect. Under EDC stress, only the concentrations of colloidal polysaccharides and proteins responded dose-dependently to EE2. Except for the colloidal fraction in the EE2 treatment group, the increase in neutral monosaccharides, especially glucose and galactose, was a common response to EDCs. Compared to the recalcitrant BPA, NP underwent abiotic degradation in alga-free water, and EE2 could be biodegraded in water containing this microalga. The chemical-specific responses of cell growth, chlorophyll and related EPS profiles were driven by the different fates of EDCs, and the underlying mechanism was further discussed. The results obtained in the present work are of critical importance for understanding the fate and effects of different EDCs mediated by microalgae and their related EPSs.

Prorocentrum lima is a cosmopolitan benthic dinoflagellate capable of producing the diarrhetic shellfish toxins (DSTs) okadaic acid (OA) and dinophysistoxin (DTX). These compounds may cause oxidative stress and accumulate in bivalve tissues, which become vectors of intoxication to human consumers. We investigated DST accumulation, detoxification and oxidative stress biomarkers in clams (Anomalocardia flexuosa) experimentally exposed to P. lima cells or their compounds. Experimental diets consisted of 6000 cells mL-1 of the non-toxic chlorophyte Tetraselmis sp. (C; control condition), and combinations of C with 10 P. lima cells mL-1 (T10), 100 P. lima cells mL-1 (T100), or to a toxin concentration of ∼4 μg OA L-1 and ∼0.65 μg DTX-1 L-1 (T100d). Clams were exposed to these diets for 7 days (uptake phase), followed by a 7-day depuration period. No DSTs were detected in clams exposed to treatments C (control) nor to T100d (dissolved compounds) during either uptake or detoxification phase. Conversely, clams exposed to T10 or T100 accumulated, on average, up to 2.5 and 35 μg DST kg-1 in their whole bodies at the end of the uptake phase. These concentrations are ∼64 and ∼4.5 times lower than the regulatory level of 160 μg OA kg-1, respectively. Accumulated OA quotas were 12-22 times higher in the digestive gland (DG) than in remaining tissues over the uptake phase. Quick toxin transformation was indicated by the early detection of conjugated compounds - DTX-1 and OA esters - in the DG after 6 h of exposure, with OA-ester representing the main compound (30 - 100 %) in that tissue over the experiment. During the depuration period, detoxification rates represented 0.024 h-1, 0.04 h-1 and 0.052 h-1 for OA, DTX-1 and OA-ester, respectively. The activities of catalase, glutathione S-transferase, glutathione peroxidase and the levels of oxidative stress by lipoperoxidation varied similarly in the DG of A. flexuosa individuals subjected to T100, T100d and the control condition. However, contrasting antioxidant responses were measured in those exposed to T10. These findings indicate that no oxidative stress was primarily induced by DST-producing dinoflagellates in this clam species under laboratory conditions representative of toxic bloom situations. Even though, possible interactions should be considered under multistressor scenarios.

Corrosion control on petroleum pipe wells can only be done through the addition of corrosion inhibitors. In this study, the corrosion inhibitors studied were sourced from marine microorganisms, namely the type of microalgae Tetraselmis chuii sp. The aim to be achieved in this study was to determine the mechanism and efficiency of inhibition of the extraction of microalgae biomass in corrosion of carbon steel in an environment of petroleum conditions. To achieve this goal, a potentiodynamic polarization method (Tafel extrapolation) was used and the Electrochemistry Impedance Spectroscopy (EIS) method used the galvanostat-potentiostat device (Voltalab 40, PGZ 301). The results obtained from this study indicate that API 5L X65 carbon steel in the petroleum environment is very significantly corroded, caused by acidic media derived from acetic acid and dissolved CO2. The inhibition ability of the Tetraselmis chuii sp. Biomass extract. in line with the increasing extraction concentration reaching optimum at a concentration of 250 ppm with inhibition efficiency reaching 70%. The mechanism of inhibition takes place through the formation of a protective layer adsorbed on the surface of carbon steel. The protective membrane formed is uneven and tends to be porous.

The presence of pharmaceutical and personal care product (PPCP) residues in the aquatic environment is an emerging issue due to their uncontrolled release through gray water, and accumulation in the environment that may affect living organisms, ecosystems and public health. The aim of this study is to assess the toxicity of benzophenone-3 (BP-3), bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT), butyl methoxydibenzoylmethane (BM), methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT), 2-ethylhexyl salicylate (ES), diethylaminohydroxybenzoyl hexyl benzoate (DHHB), diethylhexyl butamido triazone (DBT), ethylhexyl triazone (ET), homosalate (HS) and octocrylene (OC) on marine organisms from two major trophic levels, including autotrophs (Tetraselmis sp.) and heterotrophs (Artemia salina). In general, results showed that both HS and OC were the most toxic UV filters for our tested species, followed by a significant effect of BM on Artemia salina due to BM&mdash, but only at high concentrations (1 mg/L). ES, BP3 and DHHB affected the metabolic activity of the microalgae at 100 &micro, g/L. BEMT, DBT, ET, MBBT had no effect on the tested organisms, even at high concentrations (2 mg/L). OC toxicity represents a risk for those species, since concentrations used in this study are 15&ndash, 90 times greater than those reported in occurrence studies for aquatic environments. For the first time in the literature, we report HS toxicity on a microalgae species at concentrations complementing those found in aquatic environments. These preliminary results could represent a risk in the future if concentrations of OC and HS continue to increase.

This study aims to determine the maximum specific biomass growth rates of Nannochloropsis gaditana and Tetraselmis chuii grown in sequential batch reactors. The maximum specific growth rates of N. gaditana and T. chuii were found to be 0.23 ± 0.04 gVSS/gVSS⋅d and 0.22 ± 0.05 gVSS/gVSS⋅d respectively. Optical density measured at 550 nm (OD550) accurately predict volatile suspended solids (VSS) concentration in N. gaditana growth media but not in T. chuii growth media. We observed decoupling of nitrate uptake from cell growth for both microalgae as growth continued well beyond the point where concentrations of nitrate in the growth media fell below the detection limit. This nitrate decoupling highlights the challenges in current microalgae growth models as growth was independent of the extracellular dissolved nitrogen in the system.

The presence of pharmaceutical and personal care products’ (PPCPs) residues in the aquatic environment is an emerging issue due to their uncontrolled release, through grey water, and accumulation in the environment that may affect living organisms, ecosystems and public health. The aim of this study is to assess the toxicity of benzophenone-3 (BP-3), bis-ethylhexyloxyphenol methoxyphenyl triazine (BEMT), butyl methoxydibenzoylmethane (BM), methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT), 2-Ethylhexyl salicylate (ES), diethylaminohydroxybenzoyl hexyl benzoate (DHHB), diethylhexyl butamido triazone (DBT), ethylhexyl triazone (ET), homosalate (HS), and octocrylene (OC) to marine organisms from two major trophic levels including autotrophs (Tetraselmis sp.) and heterotrophs (Artemia salina). In general, EC50 results show that both HS and OC are the most toxic for our tested species, followed by a significant effect of BM on Artemia salina but only at high concentrations (1 mg/L) and then an effect of ES, BP3 and DHHB on the metabolic activity of the microalgae at 100 μg/L. BEMT, DBT, ET, MBBT had no effect on the tested organisms, even at high concentrations (2mg/L). OC toxicity represent a risk for those species since it is observed at concentrations only 15 to 90 times higher than the highest concentrations reported in the natural environment and HS toxicity is for the first time reported on microalgae and was very important on Tetraselmis sp. at concentrations close to the natural environment concentrations.

Four different strains of marine algae viz. Tetraselmis tetrathele, Tetraselmis striata, Tetraselmis chuii, and Tetraselmis gracilis were isolated from the saltpans in Kovelong, Chennai, Tamil Nadu, India. The systematic position of Tetraselmis striata BBRR1 was confirmed through molecular identification. Under laboratory conditions, T. striata Butcher BBRR1 grown in f/2-medium recorded highest biomass concentration of 0.58 ± 0.021 g L−1, volumetric productivity of 0.025 ± 0.004 g L−1 d−1, 19 ± 2.3% proteins, 17 ± 1.5% carbohydrates, and 15 ± 2.4% lipids. Volumetric biomass productivity of 0.063 ± 0.08 g L−1 d−1, specific growth rate of 0.45 day−1 and lipid content of 19.42 ± 0.98% were recorded for the alga T. striata Butcher BBRR1 cultivated in 10-m2 open raceway ponds using Modified CFTRI ABRR1 medium. The fatty acid profile of T. striata Butcher BBRR1 showed the presence of 33.14% palmitic acid, 22.64% 11-octadecenoic acid, and 21.94% heptadecanoic acid. This study confirms the feasibility of cultivating the marine alga T. striata in open raceway ponds to produce biomass, which can be used for the production of biofuels.

Pulsed electric fields (PEF) is a promising technology that allows the selective extraction of high-added value compounds by electroporation. Thus, PEF provides numerous opportunities for the energy efficient isolation of valuable microalgal bioactive substances (i.e., pigments and polyphenols). The efficiency of PEF-assisted extraction combined with aqueous or dimethyl sulfoxide (DMSO) solvents in recovering pigments and polyphenols from microalgae Tetraselmis chuii (T. chuii) and Phaeodactylum tricornutum (P. tricornutum) was evaluated. Two PEF treatments were applied: (1 kV/cm/400 pulses, 3 kV/cm/45 pulses), with a specific energy input of 100 kJ/kg. The total antioxidant capacity (TAC) was positively influenced by the use of DMSO. The highest TAC in the T. chuii culture was achieved at a lower extraction time and electric field than for P. tricornutum. The use of DMSO only improved the polyphenols&prime, extraction for P. tricornutum, whereas the PEF and extraction time were more important for T. chuii. Carotenoids and chlorophyll a were more efficiently extracted using DMSO, while chlorophyll b levels were higher following aqueous extraction for both microalgae. In P. tricornutum, the TAC and pigment extraction efficiency were in general higher at lower extraction times. It can be concluded that PEF may be a promising alternative for the enhancement of the selective extraction of antioxidant bioactive compounds from microalgae.

Recently isolated microalgae Tetraselmis sp. IMP3, Tetraselmis sp. CTP4, and Skeletonema sp. were studied. The three novel strains contained relatively high levels of polyunsaturated fatty acids (PUFA) and n3 PUFA. However, highly unsaturated n3 FA contents were relatively low (5.7-13.0% of the total FA). In general, eicosapentaenoic acid (EPA, 20:5 n3) contents were low (< 6.4% of the total FA). However, in Skeletonema biomass, EPA levels were higher than 10% of the total FA. alpha-Linolenic acid (ALA, 18:3 n3) and 16:3 n4 were the main PUFA in Tetraselmis strains and Skeletonema, respectively. High contents of myristic (14:0) and palmitoleic (16:1 n7) acids were found in Skeletonema (exceeding 20% of the total FA in both cases), whereas the Tetraselmis strains were rich in palmitic (16:0), 15-27% of the total FA, and oleic (18:1 n9) acids, 12-19% of the total FA. Linoleic acid (18:2 n6) content was low in Skeletonema (< 1% of the total FA). This microalga had the highest total polyphenol content, reaching 300-400 mg/100 g dw. Gentisic acid was the main phenolic compound in the aqueous and ethanolic extracts of this microalga. The highest antioxidant activity was displayed by Skeletonema. The ferric ion reducing antioxidant power (FRAP) and 2,2 '-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) methods showed higher antioxidant power for Skeletonema sp. extracts, reaching an ABTS reduction of more than 80%. Concerning anti-inflammatory activity, ethanolic extracts of Skeletonema sp. exhibited the highest inhibitory capacity of cyclooxygenase-2 (COX-2), 82 +/- 2%, which compares to 36 +/- 9% in Tetraselmis sp. CTP4 and 45 +/- 5% in Tetraselmis sp. IMP3. Aqueous extracts had always a lower anti-inflammatory capacity, 6-30%. Therefore, these microalgae have potential for multiple applications, ranging from bioactive feedstocks to aquaculture and nutraceutical uses. SFRH/BPD/102689/2014, (SFRH/BD/129795/2017, SFRH/BD/105541/2014, project 0055 ALGARED+ 5E-INTERREG V-A info:eu-repo/semantics/publishedVersion

Lipid-extracted microalgae (LEM, Tetraselmis KCTC 12236BP), a solid waste by-product obtained from algal biodiesel production, is typically considered a rich source of antioxidant compounds, including phenolic compounds. The purpose of this study was to apply a statistically-based methodology to enhance the extraction of total phenolic compounds (TPCs) and antioxidant activity (AA) from LEM and to verify the production of epigallocatechin gallate (EGCG), a bioactive material, under optimum conditions. The optimal extractions of TPC and AA were explored by varying the key variables, including the extraction temperature, ethanol concentration, extraction time, and ultrasonic power, through statistical optimization. The optimal extraction conditions were identified through 27 runs following the central composite design. The regression analyses of TPC and AA showed good fit of the experimental data to the second-order polynomial models, with coefficient of determination (R2) values of 0.8769 and 0.8432, respectively. In the variation experiment, the maximum TPC and AA values of 9.8 mg GAE/g and 91.8% were obtained respectively with an extraction temperature of 74.4 &deg, C, ethanol concentration of 55.4%, extraction time of 59.6 min, and ultrasonic power of 700 W. HPLC coupled with diode array detection was used to identify and quantify the phenolic compounds in the extracts, and EGCG (0.12 mg/g DM) was identified as a major peak in the analysis, demonstrating that high value-added material with a bioactive property can be produced from LEM. The results indicated that statistical optimization is applicable for optimizing the extraction of TPC and AA from LEM and provided a scientific basis for applying ultrasound-assisted extraction on an industrial scale by optimizing the conditions. LEM has a high TPC value, particularly with regard to EGCG, and excellent AA, considering it is highly used as a functional material for food, cosmetics, and medicine.

Several species of the genus Tetraselmis (Chlorodendrophyceae, Chlorophyta) were recently discovered to possess unsuspected biomineralization capacities: they produce multiple intracellular inclusions of amorphous calcium carbonate (ACC), called micropearls. Early light-microscopists had spotted rows of refractive granules in some species, although without identifying their mineral nature. Scanning electron microscope (SEM) observations showed that the distribution of the micropearls in the cell forms a pattern, which appears to be characteristic for a given species. The present study shows that this pattern correlates with the shape of the chloroplast, which differs between Tetraselmis species, because micropearls align themselves along the incisions between chloroplast lobes. This was observed both by SEM and in live cells by light microscopy (LM) using Nomarski differential interference contrast. Additionally, molecular phylogenetic analyses, of rbcL and ITS2 gene sequences from diverse strains of Chlorodendrophyceae, corroborated the morphological observations by identifying two groups among nominal Tetraselmis spp. that differ in chloroplast morphology, micropearl arrangement, and ITS2 RNA secondary structure.

The suitable culture condition for specific microalgae species is vitally important for their optimal growth and biochemical production. Therefore, this study emphasized on the isolation and screening of indigenous microalgae species with high growth performance from Setiu wetlands, Terengganu, Malaysia. Successfully isolated microalgae were identified based on morphological and molecular approaches using 18S rDNA technique. Microalgae were screened to identify their species with high growth performance based on optical density and Nile red fluorescence dye. Further, the effect of different salinity towards the growth performance of isolated microalgae and proximate composition including protein, lipid, and carbohydrate were identified. Out of nine microalgae strain, three species of indigenous microalgae were successfully isolated and identified known as Chlorella vulgaris, Tetraselmis chuii, and Isochrysis galbana during 16 days of culture period. The highest optical density was found in C. vulgaris, T. chuii, and I. galbana with 1.228 ± 0.039 a.u, 0.758 ± 0.024 a.u and 0.853 ± 0.048 a.u, respectively. Chlorella vulgaris, T. chuii, and I. galbana were also showed the highest specific growth rate with 0.548 μmax/day, 0.686 μmax/day and 0.478 μmax/day, respectively. Using Nile red fluorescent dye screening, C. vulgaris, T. chuii and I. galbana also showed the highest fluorescence intensity of lipid, carotenoid and chlorophyll a content. Based on these criteria, C. vulgaris, T. chuii and I. galbana were selected for further determination on the effect of salinity towards the growth and proximate composition of the selected microalgae. The optimum salinity level of culture medium for T. chuii was 40 ppt with the highest cell density (6.215 × 106 cells/mL; Day 6), protein content (40.47 ± 0.51% of dry weight) and carbohydrate content (42.57 ± 0.83% of dry weight). For I. galbana, 24 ppt was found to be the best culture medium in term of the highest cell density (20.58 × 106 cells/mL; Day 7), and carbohydrate content (29.28 ± 0.47% of dry weight), while lipid content was highest at 40 ppt (15.68 ± 0.58% of dry weight). For C. vulgaris, 10 ppt was the best culture medium in term of the highest cell density (31.17 × 106 cells/mL) and lipid content (13.12 ± 1.12% of dry weight), while carbohydrate and protein content were highest at 0 ppt with 44.53 ± 0.56% and 40.16 ± 2.22% of dry weight, respectively. Overall, the variation of salinity had affected the growth and biochemical compositions of C. vulgaris, T. chuii and I. galbana. Therefore, this study is important for the cultivation of C. vulgaris, T. chuii and I. galbana of different specific target by manipulating the salinity variation of culture medium that can be used as a feed in aquaculture industry.

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.

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.

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.

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%).

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.

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.

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.

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.

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.

Hydrothermal liquefaction (HTL) is a thermal depolymerization process used to convert wet biomass such as microalgae into bio-crude oil. Four main products, gas, bio-crude oil, an aqueous phase, and solid residue, are generated through HTL. In this study, various HTL conditions were investigated to enhance the phosphorus content in the aqueous phase as well as the yield of bio-crude oil. Tetraselmis sp. was used as the microalgae feedstock, and the product yields according to catalyst type were explored. The phosphate ion (PO43−) content in the aqueous phase was significantly enhanced when acetic acid was added because of the effect of pH. In addition, it was found that both the bio-crude oil yield and the ammonium ion content could be increased by recycling the post-HTL aqueous phase, while the phosphate content was not.

Shrimp is an important traded fishery commodity. When subjected to stress, shrimp usually suffers from oxidative stress, which leads to cell injury, senescence, and death. To maintain shrimp good health, performance and production, antioxidant and immune systems are important. Natural antioxidants found in microalgae may be used to increase the cell protection against oxidative damage, being a promising alternative to the carcinogenic synthetic antioxidants. In this study, Tetraselmis chuii was evaluated for its effect on survival, growth and oxidative stress biomarkers on Litopenaeus vannamei postlarvae (PL). The antioxidant properties of the formulated feed with T. chuii inclusion were determined using four antioxidant chemical assays. Meanwhile, the oxidative stress biomarkers on PL were analyzed by hydrogen peroxide, membrane stability and lipid peroxidation assays. Results showed that PL reared on diets supplemented with 50% T. chuii had a significantly higher (P ≤ 0.05) survival (97.6 ± 1.4%) and lower oxidative stress in terms of hydrogen peroxide content (10.08 ± 0.4 mM g−1 FW) and electrolyte leakage (10.8 ± 0.3%). The result of this study also showed that shrimp PL reared on diets supplemented with microalgal, T. chuii have high resistance to reverse salinity stress test (76.7–100%). However, no significant differences (P ≥ 0.05) were found in the growth and lipid peroxidation. Due to the positive effect on oxidative stress status, survival and resistance to salinity stress, the feeding of L. vannamei PL with diet containing at least 50% of T. chuii is recommended as a natural source of antioxidant for PL.

To increase the carotenoid-rich biomass production, various exogenous conditions as well as nutritional stress in terms of carbon sources were tested using a yeast strain, Rhodotorula mucilaginosa AY-01, isolated as a carotenoid producer. Biomass and carotenoid production were monitored according to the type of substrates. For cost reduction and carbon source recycling in bio-refinery, crude biomass designated to microalgal wastes was collected from Tetraselmis tertiolecta KCTC12432BP. Afterward it was used for the biodiesel production and considered as suitable carbon source for the cultivation of R. mucilaginous AY-01. The results indicated about a 27% increase in total biomass and 15.7% increase in carotenoid production respectively, as compared to glycerol supplemented medium. It is worth to note that microalgal wastes substrate can be used as an alternative carbon and nitrogen sources for the cultivation of R. mucilaginous AY-01 and contribute to the enhancement of the economic competition of biodiesel production from microalgae.

Even though hydrothermal liquefaction (HTL) is a promising route to produce crude oils (referred to as “green crude”), the molecular composition of the nitrogen fraction of such green crude oils is not fully understood. The goal of this work was to identify and quantify the fraction of fatty amides in green crude oils obtained from five different samples derived from Desmodesmus armatus, Tetraselmis sp., and Chlorella sp. biomass treated under different HTL conditions (260 or 340 °C as batch or continuous processes). The goal of this work was to elucidate the nature of the high nitrogen content of the green crude oils. We identified at least 19 distinct fatty amides present in green crude oils and quantified them based on relevant standards in purified fractions after functional group-based separation and enrichment. It was not known how much these compounds contributed to the oils or which molecular fraction they are associated with. We found that fatty amides exclusively partitioned with the neutral fra...

Isolation, quantification and characterization of bioactive compounds from microalgae Tetraselmis species have been performed to elucidate the potential use as a bioactive material. Microalga are a promising source of lipids for biofuel production and represent a diverse group of microscopic photosynthetic organisms and are able to convert solar energy into biomasses. The imposition of oxidative stresses by various environmental factors leads to the production of reactive oxygen species (ROS) in plant cells, including algal cell. Antioxidant activity of water soluble bioactive substances (WSBS) was determined by DPPH, ABTS, FRAP and similar SOD radical-scavenging assay. The content analysis of lipid, sugar, polyphenol and protein was performed to evaluate the potent usefulness of WSBS from the whole cells cultivated under the optimum conditions for the production of biodiesel. The yield of WSBS was determined to be 17% based on the total carbohydrate assay. The relative activity of WSBS toward FRAP and DPPH reagent was observed ranging from 13 to 55%, showing the significant anti-oxidative properties with wide range of temperatures from room temperature to 80℃. The outcomes of this study support utilization of WSBS from microalgae Tetraselmis species as a potential source of naturally occurring antioxidants.

The use of biomass of microalgae as a feedstock to produce bioethanol is very promising, it is caused by a large amount of carbohydrates contained in microalgae physiology cell. The main obstacle of enzymatic hydrolysis in order to produce bioethanol is the bound starch granules in a rigid cell wall. Therefore, pre-treatment steps needed to remove and convert complex carbohydrates into simple sugars before the fermentation process. Tetraselmis Chuii microalgae species are green microalgae (Chlorophyta) in which the cell wall containing cellulose and hemicellulose as the main constituent, therefore, this study observe the effect of the use of cellulase enzymes and xylanase as a strategy to open up the cell walls of microalgae. Another investigated parameter is the enzyme concentration, temperature, pH, and methods of use of enzymes. The results showed that the highest yield of glucose obtained was 31.912% (w / w) and is achieved under the conditions of a temperature of 45oC, pH of 4.5, the amount of biomass of microalgae as 5 g/L, the concentration of cellulase enzymes and xilanase 30% (w / w) at 40 minute at mechanism using cellulase and xylanase enzymes simultaneously.

Water soluble polysaccharides (WSPs) were isolated from defatted microalgae Tetraselmis sp. KCTC 12432 BP (T.S1) and KCTC 12236 BP (T.S2), and purified by a combination of ethanol precipitation, immobilized metal affinity chromatography and size-exclusion column chromatography. Biochemical properties of WSPs obtained from the supernatant (S 1 and S 2) and purification steps (EP 1 and EP 2) have been elucidated for their potential use as a biologically active material. Oxidative effect on efficiency from the hydrolytic fenton reaction (FS 1 and FS 2) was also employed to assess the WSPs production and biological activity from T.S1 and T.S2, respectively. Antioxidant activity of the purified WSPs from EP 2 toward 1,1-diphenyl-2-picryl-hy-drazyl (DPPH), 2,2’-Azinobis (3-ethylbenzothiazoline-6-sulfonic acid) di-ammonium salt (ABTS), and ferric reducing antioxidant power (FRAP) of radical-scavenging showed significant differences depending on the monosaccharide compositions of WSPs. On the other hand, a significant specific tyrosinase inhibitory activity was observed from the WSPs purified from EP 1 (10 ¼mol/g/min) indicating the potential use as a whitening source. The outcomes of our study support the utilization of WSPs from these microalgal species as a potential source of naturally occurring whitening and antioxidants to ease oxidative stresses. According to our knowledge related to microalgal studies, until now this is the first study which demonstrates the significance between primary structure and potential biological activities of WSPs purified from the defatted microalgae Tetraselmis species.

Modification of algae–silica (AS) hybrid material from Tetraselmis sp. biomass (AS) was performed through a sol–gel simultaneous process and coated with Fe3O4 magnetite nanoparticles (MNPs). Algae–silica hybrid material from Tetraselmis sp. biomass-coated MNPs (AS-MNPs) were used as adsorbents of heavy metal ions. The adsorption processes of Ni(II), Cu(II), and Zn(II) ions with AS and algae-silica-magnetite nanoparticles (AS-MNPs) fit pseudo-second-order kinetic models. The rate constant and adsorption capacity of Ni(II), Cu(II), and Zn(II) ions for AS-MNPs obtained from these experiments were higher than those of AS. AS-MNPs material is an effective adsorbent and can be used to absorb heavy metal ions in solution.

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.

Bisphenol-A (BPA) is a chemical used in the production of polycarbonate plastic and epoxy resins that may be related to the occurrence of human endocrine disorders. The present study aims to indicate a microalgae for use in ecotoxicological tests concerning BPA contamination of aquatic environments by analyzing its toxicity for the freshwater species Pseudokirchneriella subcapitata, and the two marine species Tetraselmis chuii and Skeletonema costatum. The standardization of the test involved determination of suitable nominal concentrations of BPA and the most appropriate species for use as biomarkers. S. costatum and P. subcapitata demonstrated resistance to BPA, features that are not of interest for toxicity markers. T. chuii presented an adequate sensitivity to BPA, compatible with parameters used in human toxicology for this substance, and is indicated as a potential biomarker for the presence of BPA in marine environments. The IC50 of T. chuii was 2.5 μM with R2 = 0.9, indicating reliability to demonstrate that low concentrations of BPA has significant toxicity to this species.

In recent years, there has been increasing consumer interest in carotenoids, particularly of marine sustainable origin with applications in the food, cosmeceutical, nutritional supplement and pharmaceutical industries. For instance, microalgae belonging to the genus Tetraselmis are known for their biotechnologically relevant carotenoid profile. The recently isolated marine microalgal strain Tetraselmis sp. CTP4 is a fast-growing, robust industrial strain, which has successfully been produced in 100-m3 photobioreactors. However, there are no reports on total carotenoid contents from this strain belonging to T. striata/convolutae clade. Although there are several reports on extraction methods targeting chlorophytes, extraction depends on the strength of cell coverings, solvent polarity and the nature of the targeted carotenoids. Therefore, this article evaluates different extraction methods targeting Tetraselmis sp. CTP4, a strain known to contain a mechanically resistant theca. Here, we propose a factorial experimental design to compare extraction of total carotenoids from wet and freeze-dried microalgal biomass using four different solvents (acetone, ethanol, methanol or tetrahydrofuran) in combination with two types of mechanical cell disruption (glass beads or dispersion). The extraction efficiency of the methods was assessed by pigment contents and profiles present in the extracts. Extraction of wet biomass by means of glass bead-assisted cell disruption using tetrahydrofuran yielded the highest amounts of lutein and β-carotene (622 ± 40 and 618 ± 32 µg g-1 DW, respectively). Although acetone was slightly less efficient than tetrahydrofuran, it is preferable due to its lower costs and toxicity. info:eu-repo/semantics/publishedVersion

The effects of bio-optical characteristics on lipid and biomass production rates for Emiliania huxleyi and Tetraselmis sp. were studied under different irradiances and spectra. Biomass and lipid production increased from irradiances of 50–800 μE m−2 s−1 but differed for each spectrum. The highest biomass and neutral lipid production rates for E. huxleyi occurred under a red-blue LED array, which mimicked the absorption spectra of the cell’s chlorophyll a and accessory pigments, especially fucoxanthins. Biomass and neutral lipid production for Tetraselmis sp. were enhanced under broader spectra of cool white and grow lights. Neutral lipids per cell volume were similar for the two species and inversely proportional to chlorophyll a concentrations. High biomass and neutral lipid production rates were associated with high total quantum absorption and low quantum absorption per cell. Generally, quantum efficiencies were highest for high light treatments with high total quantum absorption and high production rates. Using reconstructed quantum absorption by pigments, the bio-optical model showed that photoprotective pigments were dependent on light intensity and spectra. Quantum efficiencies increased when excluding the contribution of photoprotective pigments to total quantum absorption since they did not directly contribute to photosynthesis, but did promote higher production rates.