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An innovative microalgae harvesting technique using electroflocculation was carried out at different voltage treatments (4, 7, and 9 V) using a fabricated voltage regulator and compared with harvesting by electroflocculation at 12 V using a car battery to efficiently electroflocculate Tetraselmis tetrathele. This study was conducted to determine the ideal voltage settings that could improve the quality of harvested paste in terms of nutritional value and metal contamination for its later use in aquaculture. The use of 7 V achieved low Pb content producing the best harvest biomass (1.4 kg, 87 min) which is comparable to the harvest biomass (1.7 kg, 68 min) using a 12 V car battery. Storage of T. tetrathele paste is best done in a chiller (2 ± 1 °C) rather than a freezer (-20 ± -4 °C) for ease in reactivation and maintaining higher cell viability for later use as a starter in aquaculture. Storage in a chiller allows T. tetrathele paste to be resuspended after six months and used as a starter culture. [ABSTRACT FROM AUTHOR]

Wastewaters contain nutrients that can be used as culture media for microalgae. In this study, density, growth, and biochemical compositions (protein, lipid and carbohydrates) of Tetraselmis tetrathele were investigated using mollasse and beer wastewater. A completely randomized experimental design was performed containing treatments; Conway, mollasse, and beer wastewater in two concentrations of diluted (5 ml per liter of culture medium, v/v), and concentrated (10 ml per liter of culture medium, v/v) over a 11-day period. The highest cell density was obtained in the concentrated mollasse treatment (96.7×103 cells per ml) and the highest specific growth rate obtained in the dilute Conway treatment (15.5 per day). In addition, the highest amount of protein and lipid (39.5% and 8.1%, respectively) was measured in the concentrated beer treatment and the lowest recorded in the concentrated Conway treatment (10.70% and 2.98%, respectively). The highest amount of carbohydrates (28.92%) was obtained in diluted mollasse treatment. Therefore, based on the results of growth rate and biochemical compositions of T. tetrathele, it can be concluded that the beer and mollasse wastes are suitable media for growth of T. tetrathele. [ABSTRACT FROM AUTHOR]

Microalgae can use either ammonium or nitrate for its growth and vitality. However, at a certain level of concentration, ammonium nitrogen exhibits toxicity which consequently can inhibit microalgae productivity. Therefore, this study is aimed to investigate the tolerance of Tetraselmis tetrathele to high ammonium nitrogen concentrations and its effects on growth rate, photosynthetic efficiency (Fv/Fm), pigment contents (chlorophyll a, lutein, neoxanthin, and β-carotene), and fatty acids production. Experiments were performed at different ammonium nitrogen concentrations (0.31–0.87 gL−1) for 6 days under a light source with an intensity of 300 μmol photons m−2 s−1 and nitrate-nitrogen source as the experimental control. The findings indicated no apparent enhancement of photosynthetic efficiency (Fv/Fm) at high levels of ammonium nitrogen (NH4+-N) for T. tetrathele within 24 h. However, after 24 h, the photosynthetic efficiency of T. tetrathele increased significantly (p < 0.05) in high concentration of NH4+-N. Chlorophyll a content in T. tetrathele grown in all of the different NH4+-N levels increased significantly compared to nitrate-nitrogen (NO3-N) treatment (p < 0.05); which supported that this microalgal could grow even in high level of NH4+-N concentrations. The findings also indicated that T. tetrathele is highly resistant to high ammonium nitrogen which suggests T. tetrathele to be used in the aquaculture industry for bioremediation purpose to remove ammonium nitrogen, thus reducing the production cost while improving the water quality.

The integration of two-stage microalgal cultivation and abiotic stresses is considered a cost‐effective and simple strategy for enhancing both primary and secondary metabolites in microalgae. Here, two-stage cultivation of Tetraselmis tetrathele in Conway medium (CM) and food factory wastewater (FWW) was performed. The stationary phase was observed after eight days (first stage) with the highest microalgal dry weight of 2.70 g/L in CM and 2.51 g/L in FWW. In the second stage, microalgal cultures were exposed to different light intensities (100 and 300 μmol photons/(m2.s) of LED and 35 and 100 μmol photons/(m2.s) of fluorescent lamp) and salinities (25 and 40 g/L) for three days. In FWW and CM cultures, illuminated with a fluorescent lamp at 35 μmol photons/(m2.s) and having 40 g/L salinity, the maximum total phenolic compounds (TPCs) were found to be 17.57 and 15.02 mg GAE/g dry weight, respectively. These results showed that salinity stress stimulates the accumulation of TPCs in T. tetrathele. The highest flavonoid yield was found to be 5.18 and 5.12 mg QE/g dry weight in CM under LED light stress of 300 μmol photons/(m2.s) and salinity stress of 40 g/L, respectively. Increasing fluorescent light intensity from 35 to 100 μmol photons/(m2.s) and LED light intensity from 100 to 300 μmol photons/(m2.s) maximized saturated fatty acids to 48.72 % in CM and to 41.86 % in FWW. Moreover, salinity and light stresses influenced microalgal biodiesel properties, such as the cetane number (CN) value. The results of this study can be applied to enhance microalgal bioactive compounds based on their cultivation conditions. [Display omitted] • Tetraselmis tetrathele was cultivated in food wastewater (FWW) and Conway medium. • Integration of two-stage microalgal cultivation and abiotic stresses was studied. • Co-production of biodiesel and phenolic compounds was investigated. • Salinity stress maximized microalgal total phenolic compounds to 17.57 mg GAE/g DW. • The highest cetane number value was found as 52.26 in FWW under LED light stress. [ABSTRACT FROM AUTHOR]

This work aims at the induction of the synthesis bioactive compounds in microalgae which are used in aquacultures. Experiments were done using Tetraselmis tetrathele in batch culture for 8 days under different salinity levels. The growth of the alga at salinity 20 ppm was increased by fivefold and synthesis of carotenoids by 20-fold in comparison to the controlled. Increasing NaCl concentration resulted in increasing the fatty acid accumulation in T. tetrathele cells. Saturated fatty acids were the main constituent in the fatty acid methyl esters (FAMEs) (3.48 mg/g) at salinity 25 ppm. The predominated fatty acids were tridecylic, myristic and pentadecanoic which have potential antimicrobial activities. GC–MS analyses of the alga acetone extract grown under different NaCl concentrations were established. The results showed the presence of 18 bioactive compounds: 9-octadecenamide; in addition to the different esters of some fatty acids: hexanedioic, 1,2-cyclohexanedicarboxylic, phthalic, oleanitrile, hexanedioic and 1,2-cyclohexanedicarboxylic (71.5%; 64.9%; 55.4%; 49.6%; 18.7%; 25.2% and 14.5%, respectively). The study suggested that the alga biosynthesized various bioactive compounds under different salinity levels as defense mechanisms. Accordingly, the growth of T. tetrathele under salinity stress before being used in aquacultures is recommended.

The Closed Ecological Recirculating Aquaculture System (CERAS) simulates the food chain of hydrosphere and also includes materials cyclical type of food production systems. In the present study, the nourishment salt form kuruma shrimp aquacultural waste (waste water, foam liquid) collected from the CERAS was used as a medium to raise Chaetoceros gracilis and Tetraselmis tetrathele . F medium was used as a control. The results show that although the growth speed of C. gracilis which cultured in aquacultural waste + Manganese medium was 1 day slower compare with the F medium, there were no significant difference in the lipid composition and the fatty acid, amino acid compositions profile of C. gracilis and T. tetrathele between two groups. Fed shrimp larvae on the algae collected form the two groups for 3 weeks until post-larva stage and collect the shrimp larvae as analytical samples, and then they were divided into two dietary groups and the larvae fed on algae which cultured in F medium was used as a control. There were no significant differences in the larval quality and fatty acid, amino acid compositions profile of shrimp larvae between the two groups. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two-stage cultivation of Tetraselmis tetrathele was conducted in food wastewater. • Abiotic stresses were applied during stationary growth phase. • Salinity stress could enhance pigment contents of Tetraselmis tetrathele. • Salinity and light intensity stresses increased antioxidant capacity of microalgae. This study leveraged the salinity and light intensity stresses during the stationary phase for enhancing the pigment contents and antioxidant capacity of Tetraselmis tetrathele. The highest pigments content was obtained in cultures under salinity stress (40 g L−1) illuminated using fluorescent light. Furthermore, the best inhibitory concentration (IC 50) for scavenging the 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals was found as 79.53 µg mL−1 in ethanol extract and cultures under red LED light stress (300 µmol m−2 s−1). The highest antioxidant capacity in a ferric-reducing antioxidant power (FRAP) assay (1,778.6 µM Fe+2) was found in ethanol extract and cultures under salinity stress illuminated using fluorescent light. Maximum scavenging of the 2.2-diphenyl-1-picrylhydrazyl (DPPH) radical was found in ethyl acetate extracts under light and salinity stresses. These results indicated that abiotic stresses could enhance the pigment and antioxidant components of T. tetrathele , which are value-added compounds in the pharmaceutical, cosmetic, and food industries. [ABSTRACT FROM AUTHOR]

This work aims at the induction of the synthesis bioactive compounds in microalgae which are used in aquacultures. Experiments were done using Tetraselmis tetrathele in batch culture for 8 days under different salinity levels. The growth of the alga at salinity 20 ppm was increased by fivefold and synthesis of carotenoids by 20-fold in comparison to the controlled. Increasing NaCl concentration resulted in increasing the fatty acid accumulation in T. tetrathele cells. Saturated fatty acids were the main constituent in the fatty acid methyl esters (FAMEs) (3.48 mg/g) at salinity 25 ppm. The predominated fatty acids were tridecylic, myristic and pentadecanoic which have potential antimicrobial activities. GC–MS analyses of the alga acetone extract grown under different NaCl concentrations were established. The results showed the presence of 18 bioactive compounds: 9-octadecenamide; in addition to the different esters of some fatty acids: hexanedioic, 1,2-cyclohexanedicarboxylic, phthalic, oleanitrile, hexanedioic and 1,2-cyclohexanedicarboxylic (71.5%; 64.9%; 55.4%; 49.6%; 18.7%; 25.2% and 14.5%, respectively). The study suggested that the alga biosynthesized various bioactive compounds under different salinity levels as defense mechanisms. Accordingly, the growth of T. tetrathele under salinity stress before being used in aquacultures is recommended. [ABSTRACT FROM AUTHOR]

This study assessed the toxicity of water-accommodated fraction (WAF) and chemically enhanced WAF (CEWAF) of bunker C oil and dispersant (DISP) to a microalga, Tetraselmis tetrathele. The 72-h median effective concentration (72-h EC) of CEWAF and DISP were determined at 3.30 % and 2.40 %, respectively. The no observed effect concentration (NOEC) of CEWAF to T. tetrathele was at 2.0 % and lowest observed effect concentration (LOEC) was at 3.0 % while NOEC and LOEC of DISP to T. tetrathele were determined at 1.0 % and 2.0 %, respectively. The addition of dispersant to oil increased the amount of total PAH present in the CEWAF test solutions. DISP alone was highly toxic, and the toxicity of CEWAF was primarily caused by the presence of dispersant. [ABSTRACT FROM AUTHOR]

Recent developments in the technology of cryopreservation have permitted the long-term storage of many strains of microalgae with reliable rates of survival. However, many strains still cannot be recovered from storage in liquid nitrogen. Here, we investigated the effects of various cryoprotectants in achieving comparatively high survival rate around 50%. The strains tested included two freshwater algae, Chlorella vulgaris C-27 and M-207A7, and two marine algae, Nannochloropsis oculata ST-4 and Tetraselmis tetrathele T-501. Cells of these strains were suspended in various cryoprotective solutions and slowly cooled to −40°C prior to immersion in liquid nitrogen. Little or no cryoprotection was seen with dimethyl sulfoxide (DMSO) alone or in combination with sorbitol or proline; with glycerol alone; or with ethylene glycol (EG) alone. However, survival rates of approximately 50% were observed using a cryoprotectant mixture of 5% DMSO, 5% EG, and 5% proline. Viability persisted during a storage period of 15 years. Similarly, chlorophyll content was not significantly changed during this 15-year interval. Thus, the present study demonstrates the advantage of cryopreservation using liquid nitrogen. We expect that this method will contribute to both basic and applied biology through the establishment of cryopreserved microalgal culture collections. [ABSTRACT FROM AUTHOR]

The cyclopoid copepod Apocyclops dengizicus was isolated from a marine shrimp pond, Penaeus monodon, Kuala Selangor, Malaysia, and reared in the laboratory for 3 months to establish a pure population stock. Amino acids and fatty acids of A. dengizicus were determined when fed Chaetocerous calcitrans (C), Tetraselmis tetrathele (T) and their combination (CT) (1:1 by number). The protein contents in A. dengizicus that received C, T and CT were 46.8%, 60.5% and 55.3% of dry weight respectively. Correspondingly, the lipid was 19.0%, 17.8% and 19.1% of dry weight for C, T and CT respectively. The A. dengizicus cultured on C, T and CT had total essential amino acids without tryptophan measurement of 57.1, 60.3 and 67.8 and total non-essential amino acids of 42.9%, 40.0% and 32.2% of total amino acids. The fatty acid content of A. dengizicus showed that it was able to synthesize docosahexenoic acid (22:6n-3, DHA), eicosapentaenoic acid (20:5n-3, EPA) and arachidonic acid (20: 4n-6, ARA) from examined microalgal diets. The DHA:EPA:ARA ratios of A. dengizicus fed on C, T and CT were 6.8:3.0:1, 14.0:5.8:1 and 11.6:2.6:1 respectively. Apocyclops dengizicus could be suitable live food for larval fish and shrimp rearing because it meets their nutritive requirements. [ABSTRACT FROM AUTHOR]

This work had as objective to prove different types of artificial and natural zeolites, about the growth of two microalgae species used in the feeding of shrimp larvae: the diatom Chaetoceros muelleri and the flagellate Tetraselmis tetrathele. The zeolites was proven: ZEBEN-56, ZESTEC-56, AZ, BZ and CZ incorporating 10 mg/l to the means of cultivation in each case. They were carried out the cultivations in flasks of a liter, to illumination constant salinity of 35% and temperature that it oscillated from 26 to 28‰C. They were and compared the concentrations of 4 replicas in alternating days and they were determined and compared several parameters populations for the exponential phase of the cultivation. It was obtained significant differences among the treatments for the case of C. muelleri being obtained bigger concentration with the artificial zeolites due to the great contribution of silica of the same ones and to the use of this mineral on the part of the diatom, being ended up achieving 35% of more growth with ZEBEN 56 that with the control. For the case of T. tetrathele the biggest concentrations were achieved with the natural zeolite CZ being obtained 30% more than the cellular concentration compared with the control and almost twice as much compared with the artificial zeolites. In general, the use of the zeolites increased the durability of the cultivations. [ABSTRACT FROM AUTHOR]

The current research aimed to increase biomass production by manipulating the light intensity between 300 and 2500 μmol m−2 s−1 into a semi-continuous culture system. The growth productivity, photosynthetic performance, pigments, lipids, and fatty acids compositions of Tetraselmis tetrathele were closely investigated. This microalga could tolerate high light intensity (1500 μmol m−2 s−1), where the light intensity per cell ranged 13 μmol m−2 s−1 g-dw−1 cell−1 produced 2.92–3.34 g-dw L−1 of dry-cell weight during steady-state growth condition, approximately 1.8 times higher than the condition at 300 μmol m−2 s−1. Interestingly, maximal electron transport rate of photosystem II (ETR max) was induced to reflect the photoacclimation activity and accompanied with variations in pigments, lipids, and fatty acids profile to protect cells from photo-oxidative damage. The scavenging role of β -carotene as a vital photoprotective pigment was achieved upon exposure to excessive light, about 1.9-fold higher than 300 μmol m−2 s−1 light intensity. [Display omitted] • Tetraselmis tetrathele biomass increased 1.8-fold with adequate CO 2 and nutrients. • Applicability of Tetraselmis tetrathele to cope with high light stress • Better grasp of physiological factors to sustainably maximize microalgae production [ABSTRACT FROM AUTHOR]