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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.

Live feed is the basic food source and nutrient security for successful seed production of any commercially important aquaculture species of fishes, mollusks and crustaceans. Both plant and animal originated aquatic microscopic organisms are generally termed as live food. They are the basic food items in early stages (larval stage) of life cycle due to small sizes, easy digestibility and enriched in nutrients. TheNannochloropsis sp.;Nannochlorum sp. andTetraselmis sp. are rich with relatively high content of essential fatty acids in comparison to other marine algae. Likelihood, the rotiferBrachionus sp. is ideal feed item for brackishwater finfish and mud crab larvae rearing due to its special features like rapid reproduction, slow movement, suitable size and easy digestion by the newly hatched larvae. The present study is the report on comparison of growth performance of live feed (microalgae and rotifer) in outdoor culture condition. The study was conducted at the hatchery complex of Bangladesh Fisheries Research Institute, Brackishwater Station, Paikgacha, Khulna. In outdoor culture condition the growth pattern obtained for three microalgae wereTetraselmis sp.>Nannochlorum sp.>Nannochloropsis sp.Highest average growth 6.87×106±1.97×106, 6.91×106±1.69×106 and 6.23×106±1.53×106was observed forNannochloropsis sp.,Nannochlorum sp.andTetraselmis sp.respectively in trial 3. Average growth of rotifer (Brachionus sp.) found highest 189±18.10 ind./ml at combined media of yeast and microalgae and lowest growth 119.67±17.60 ind./ml noticed with baker's yeast media.Nannochloropsis sp.contains more energy among all microalgae butTetraselmis sp.carry highest level of protein. The highest level of protein 56.3±0.18% found in rotifer enriched with microalgae+fish oil and lowest protein content noticed with microalgaeenrichmentmedia.So, research finding suggests that, treatment T3 would be the best recommendations for rotifer culture.

The environmental effects of nanoplastics-NPLs have been addressed mainly through short-term exposures to a few types of polymers, neglecting other NPLs that are economically relevant like polymethylmethacrylate - PMMA. This work aimed to assess long-term effects of PMMA-NPLs on the marine primary consumer Brachionus plicatilis, evaluating the influence of different exposure routes (waterborne, foodborne and both) and food items (Nannochloropsis gaditana and Tetraselmis chuii). Rotifers were 21 days exposed to: a) control, with clean medium and food-CTR; b) contaminated medium (8.1 mg PMMA-NPLs/L) and clean algae-MC; c) clean medium and contaminated algae (pre-incubated for 96 h on 8.1 mg PMMA-NPLs/L)-AC; and, d) contaminated medium and algae–MC/AC. Mortality (lx), total number of organisms (TN), fecundity (mx), populational growth rate (r), generational time (gt), and feeding rates were assessed. Effects on r and mx were found after 21 days. Organisms from AC had higher r than MC. MC/AC organisms performed better than control in all endpoints. Overall organisms fed with N. gaditana had higher TN, mx and r than those fed with T. chuii. In the AC treatments, rotifers fed with N. gaditana had higher mx. Results highlight that exposure route and food type may modulate NPLs’ effects, supporting the need for standardization of assays.

There arose one of the most important ecological transitions in Earth’s history approximately 750 million years ago during the middle Neoproterozoic Era (1000 to 541 million years ago, Ma). Biomarker evidence suggests that around this time there was a rapid shift from a predominantly bacterial-dominated world to more complex ecosystems governed by eukaryotic primary productivity. The resulting ‘Rise of the algae’ led to dramatically altered food webs that were much more efficient in terms of nutrient and energy transfer. Yet, what triggered this ecological shift? In this study we examined the theory that it was the alleviation of phosphorus (P) deficiency that gave eukaryotic alga the prime opportunity to flourish. We performed laboratory experiments on the cyanobacteriumSynochystis salinaand the eukaryotic algaeTetraselmis sueciaand examined their ability to compete for phosphorus. Both these organisms co-occur in modern European coastal waters and are not known to have any allelopathic capabilities. The strains were cultured in mono and mixed cultures in chemostats across a range of dissolved organic phosphorus (DIP) conditions to reflect modern and ancient oceanic conditions of 0.2 μM P and 2 μM P, respectively. Our results show that the cyanobacteria outcompete the algae at the low input (0.2 μM P) treatment, yet the eukaryotic algae were not completely excluded and remained a constant background component in the mixed-culture experiments. Also, despite it’s relatively large cell size, the algaeT. sueciahad a high affinity for DIP. With DIP input concentrations resembling modern-day levels (2 μM), the eukaryotic algae could effectively compete against the cyanobacteria in terms of total biomass production. These results suggest that the availability of phosphorus could have influenced the global expansion of eukaryotic algae. However, P limitation does not seem to explain the complete absence of eukaryotic algae in the biomarker record before ca. 750 Ma.

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.

For mushroom production usually a mixture of horse and chicken manure and straw is used. For every kg of mushrooms, 5 kgs of waste is produced, a total of 800.000 tonnes per year in the Netherlands. Processing options are often either costly or complex. As the champost contains high salt concentrations, washing results in a solid (less salty) fraction with better re-use options and a nutrient-rich liquid fraction. On the latter fraction growth of five species of commercially relevant micro algae was tested in small-scale well tests. In addition, the press water was also treated with H2O2/UV to reduce the brown colour of the solution. In the majority of the triplicate well tests, growth of three of the five common saltwater algae species (Nannochloropsis gaditana, Porphyridium purpureum, and Tetraselmis chuii) on press water fractions of spent mushroom waste (champost) was found to be comparable to or better than their growth on control media. Dunaliella salina growth was relatively low. Arthrospira platensis only grew on press water when treated with H2O2. Overall, the results indicate that washing of champost results in a mineral rich solution suitable for growth of several (saltwater) algae.

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.

Ultrasonic harvesting could reduce the energy consumption and costs associated with separating microalgae from growth media. The responsiveness of microalgae cells to an ultrasonic standing wave depends on the cell radius and acoustic contrast factor (ACF). The ACF can vary as cell composition (e.g. lipid, protein, carbohydrate content) varies depending on the algae strain, cultivation conditions, and growth stage. Two independent experimental methods were used to characterize the ACF of three algae ;strains—Nannochloropsis salina, Chlamydomonas reinhardtii, and Tetraselmis chuii—as a function of dynamic cellular composition over 9- to 14-day growth periods. For N. salina, lipid content increased from 25 ± 1% to 33 ± 1% ash-free dry weight (AFDW) and ACF decreased by 46% (from 0.041 ± 0.002 to 0.022 ± 0.002) between growth days 3 and 10. For C. reinhardtii, lipid content increased from 26 ± 1% to 40 ± 1% AFDW and ACF decreased by 33% (from 0.051 ± 0.013 to 0.034 ± 0.006) between growth days 3 and 9. For T. chuii, lipid content and ACF remained stable (~ 10% AFDW and ~ 0.3) over the growth period. ACF decreased as lipid content increased because lipids have a negative ACF in the growth media; however, cell size had a greater impact on cell responsiveness because the ratio of the acoustic radiation force to the drag force is proportional to cell radius squared.

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.

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.

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.

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).

Growth pattern of five species of microalgae viz., Chaetoceros calcitrans, Dunaliella sp., Isochrysis galbana, Tetraselmis tetrahele and Nannochloropsis salina were studied under indoor controlled conditions (at 230C) and under outdoor (at 28-30°C) conditions. The variations in ammonia and pH levels in the culture flasks over a period of 90 days were also studied. Results revealed that the pattern of growth of all five species of algae were significantly different (p

CO2 fixation by phototrophic microalgae and cyanobacteria is seen as a possible global carbon emissions reducer; however, novel microalgae and cyanobacterial strains with tolerance to elevated temperatures and CO2 concentrations are essential for further development of algae-based carbon capture. Four novel strains isolated from the Arabian Gulf were investigated for their thermotolerance and CO2-tolerance, as well as their carbon capture capability. Two strains, Leptolyngbya sp. and Picochlorum sp., grew well at 40 °C, with productivities of 106.6 ± 10.0 and 87.5 ± 2.1 mg biomass L−1 d−1, respectively. Tetraselmis sp. isolate showed the highest biomass productivity and carbon capture rate of 157.7 ± 10.3 mg biomass L−1 d−1 and 270.8 ± 23.9 mg CO2 L−1 d−1, respectively, both at 30 °C. Under 20% CO2, the biomass productivity increased over 2-fold for both Tetraselmis and Picochlorum isolates, to 333.8 ± 41.1 and 244.7 ± 29.5 mg biomass L−1 d−1. These two isolates also presented significant amounts of lipids, up to 25.6 ± 0.9% and 28.0 ± 2.0% (w/w), as well as presence of EPA and DHA. Picochlorum sp. was found to have a suitable FAME profile for biodiesel production. Both Tetraselmis and Picochlorum isolates showed promising characteristics, making them valuable strains for further investigation towards commercial applications and CO2 capture. The authors would like to thank Mahroof Eroth, Dr. Ahmed Easa, and Dr. Abdulrahman Al Muftah from Qatar University, Andy Selwood from Cawthron Institute, and the QDVC team for their support. This work was supported by QDVC and Qatar University [Project QUEX-CAS-QDVC-14/15-7]. Scopus

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.

Interactions between algae and associated bacterial communities in the phycosphere depend on many factors such as culture age, nutrient availability, and antibiotic production and greatly influence algal survival and growth. The microbial community associated with the marine microalga Tetraselmis suecica F&M-M33 in a laboratory culture and an outdoor mass culture, set up from the laboratory one, run during a whole year was investigated in different seasons through isolation in pure culture of bacteria, amplified ribosomal DNA restriction analysis (ARDRA) of all the isolates, and terminal restriction fragment length polymorphism (T-RFLP) analysis. The total number of bacterial isolates was 152, which clustered in thirty-six 16S rDNA groups by ARDRA. Sequencing of a representative of each ARDRA group permitted identification of bacterial genera never reported before in association with microalgae in outdoor mass cultures, although most of them were previously found to be associated with the marine environment (e.g., seawater, sea sediments). T-RFLP analysis revealed that spring and autumn bacterial community profiles were closely related, while the bacterial laboratory community was considerably different (less than 50 % similarity) from that associated with the outdoor culture in different seasons. T-RFLP results suggest the presence of a core of bacteria that are closely associated with the alga and of a part of the community which varies seasonally.

We report the results of survival and growth in size and dry mass of spat of the Caribbean pearl oyster Pinctada imbricata cultivated under outdoor (field culture) and indoor (Laboratory) conditions. Field group fed on environmental seston. Laboratory groups were fed with mono, binary and ternary mixtures of three cultivated algae: Isochrysis galbana (Ig), Tetraselmis chuii (Ig) and the Chaetoceros sp. (Ch-A, isolated from north-eastern Venezuela). After 30 days of trial, fatty acid profiles of spat were determined along with growth in length and height shell, adductor muscle and soft tissue dry mass. During the field grow-out phase (field culture), samplings were performed at days 1, 15 and 30 to measure environmental variables of phytoplankton biomass (chlorophyll a), dissolved oxygen, seston, temperature and salinity. A significant increase in size and soft tissue mass occurred in spat fed the diets including the tropical diatom (Chaetoceros sp.). In contrast, monoalgal diets of Tc and Ig yielded no significant differences in size and mass of spat, compared with the field culture. These results suggest that nutritional requirements of cultivated spat for specific fatty acids of physiological importance for marine bivalves, such as: 16:0, 16:1n-7, 18:2n-6, 20:4n-6, 18:3n-3 and 20:5n-3, were satisfied from microalgal diets with Ch-A, alone or in combination, compared with spat fed from the field culture.

The prasinophytes (early diverging Chlorophyta), consisting of simple unicellular green algae, occupy a critical position at the base of the green algal tree of life, with some of its representatives viewed as the cell form most similar to the first green alga, the 'ancestral green flagellate'. Relatively large-celled unicellular eukaryotic phytoflagellates (such as Tetraselmis and Scherffelia), traditionally placed in Prasinophyceae but now considered as members of Chlorodendrophyceae (core Chlorophyta), have retained some primitive characteristics of prasinophytes. These organisms share several ultrastructural features with the other core chlorophytes (Trebouxiophyceae, Ulvophyceae and Chlorophyceae). However, the role of Chlorodendrophycean algae as the evolutionary link between cellular individuality and cellular cooperation has been largely unstudied. Here, we show that clonal populations of a unicellular chlorophyte, Tetraselmis indica, consist of morphologically and ultrastructurally variant cells which arise through asymmetric cell division. These cells also differ in their physiological properties. The structural and physiological differences in the clonal cell population correlate to a certain extent with the longevity and function of cells.

Dinoflagellate paralytic shellfish toxin (PST) production is mediated by several abiotic and biotic factors. This study compared the relative importance of nitrogen source and concentration, prey alarm cues and grazer presence on toxin production of the marine dinoflagellate Alexandrium catenella (Group I, strain BF-5). In separate assays run under either nutrient-replete (F/2 medium) or nutrient-depleted (filtered seawater) conditions, PST production of A. catenella was measured as a function of varying concentrations of added nitrogen sources (ammonium and urea), alarm cues from lysed conspecific (A. catenella Group I strains) and interspecific (the diatom, Thalassiosira weissflogii, and the green flagellate, Tetraselmis sp.) algae, and the presence of a grazer (the copepod Acartia hudsonica). Results showed that addition of ammonium or urea did not increase PST production. Unexpectedly, interspecific alarm cues increased toxin production but conspecific ones did not. Grazer presence dramatically induced PST production in A. catenella, irrespective of nutrient conditions, and this effect was an order of magnitude greater than any of the other variables tested. These results corroborate previous studies on grazer-induced PST production, and support the hypothesis that grazer-induced toxin production is not an experimental artifact, but rather a prey defense mechanism.

In the process of modernization and development, a human being always needed energy, which increased the dependency on the available sources of fossil fuel. Tetraselmis,a green algal genus belong to the order Chlorodendrales, are described by their strong green coloured chloroplast, flagellated cell bodies, and the occurrence of a pyrenoid within the chloroplast. In this study, four different strains of Tetraselmis species were successfully isolated from the saltpans Kovelong, Chennai, Tamil Nadu, India. The isolated strains were cultured in the normal basal medium and their morphological features were subsequently studied. The species of Tetraselmis straiata (T. straiata) Butcher BBRR1 was confirmed using molecular identification of 18S rRNA gene analysis and its observed systematic position. Among the four different isolates, T. straiata Butcher BBRR1 recorded a highest biomass concentration of 0.58 ± 0.021 g L-1, 15% lipids, 19% proteins and 17% carbohydrates when it grown under laboratory condition. Whereas, in open raceway ponds, T. straiata BBRR1 produced 0.95 ± 0.06 g L-1 biomass, 19% lipids, 28% proteins and 21% carbohydrates in an modified CFTRI I medium. The fatty acids profile of T. straiata Butcher BBRR1showed the presence of 33.14 % Palmitic acid, 22.64% 11- Octadecenoic acid and 21.94% Heptadecanoic acid. Since T. straiata BBRR1 can be cultivated in open ponds without a major contaminations, this species can be used as novel biomass feedstock to produce biofuels. This study may suggest the potential of T. straiata BBRR1 for biofuel production and could compete the energy demand in the future. In addition, this species contains healthful components of carotenoids, lipids and proteins, all these may provide a health benefits beyond basic nutrition.

The commercial production of microalgae for food applications has been the focus of much attention lately. Culturing marine microalgae in reactors with LED lamps has several advantages. Marine algae contain valuable components such as antioxidants, which are described in this report, and high salinities in production systems can lead to less contamination. By producing them in closed systems at different LED light wavelengths (colours) high biomass concentrations can be obtained and production of biomass and valuable components can be increased. This report summarizes interesting components (i.e. pigments, lipids, carbohydrates) from marine microalgae in addition to general effects of light, nutrients, salt, pressure and mutations on algae growth. The influence of several parameters on biomass growth and pigment formation of several commercially interesting marine algae species is described. These parameters include light intensity, wavelength, light path length, nitrogen source and concentration, mutagens, dilution/refreshment rates, mixing conditions, temperature, salt concentration, flashing (alternating L/D cycles), mixotrophic/phototrophic conditions, alternative nutrient sources, mixed cultures and Si addition. Species that are described in detail include Dunaliella salina and tertiolecta, Arthrospira platensis, Nannochloropsis gaditana and sp., Phaeodactylum tricornutum, Porphyridium purpureum, Tetraselmis chuii, Odontella aurita and Odontella sinensis. Het kweken van zoutwateralgen in reactoren met LED lampen heeft verschillende voordelen. Zoutwateralgen bevatten waardevolle inhoudsstoffen, zoals antioxidanten, die in dit rapport beschreven worden. Verder kan de hoge saliniteit in kweeksystemen leiden tot minder contaminatie. Door ze te kweken in gesloten systemen bij verschillende LED lichtgolflengtes (kleuren) kunnen hoge biomassaconcentraties behaald worden en kan de productie van biomassa en waardevolle inhoudsstoffen gestuurd worden. Dit rapport bevat informatie over interessante inhoudsstoffen (o.a. pigmenten, vetten, koolhydraten) uit zoutwateralgen evenals de algemene effecten van licht, nutriënten, zout, druk en mutaties op algengroei. Verder wordt de invloed van diverse parameters op biomassagroei en pigmentvorming van een aantal commercieel interessante mariene algensoorten beschreven. Dit gaat o.a. om de effecten van lichtsterkte, golflengte, lichtpadlengte, stikstofbron en concentratie, mutagenen, verdunnings/ verversingssnelheden, mengcondities, temperatuur, zoutgehalte, flashing (wisselende L/D cycli), mixotrofe/fototrofe omstandigheden, alternatieve nutriëntenbronnen, mengcultures en Si additie worden beschreven. De soorten die nader beschreven worden zijn: Dunaliella salina en tertiolecta, Arthrospira platensis, Nannochloropsis gaditana en sp., Phaeodactylum tricornutum, Porphyridium purpureum, Tetraselmis chuii, Odontella aurita en Odontella sinensis.

CO2 fixation by phototrophic microalgae and cyanobacteria is seen as a possible global carbon emissions reducer, which could also be applied to produce useful products. In Qatar, the prospect of using microalgae is very promising: high solar irradiance, large areas of non-arable land, and large amounts of CO2 sources make it an ideal place for algae cultivation. Nonetheless, application of algae in the region is limited, primarily due to a lack of suitable algae which can grow under relevant outdoor conditions, such as high temperatures, increased salinities, as well as elevated CO2 concentrations when using industrial CO2 sources. Furthermore, such algae also need to be able to produce commercially valuable products. One of the most comprehensive resources for novel algae strains in the region is the Qatar University Culture Collection of Cyanobacteria and Microalgae (QUCCCM), which houses a large diversity of strains, the potential of which still remains largely unexplored. This research focused on evaluation of biomass productivity of four novel marine strains from this culture collection, under elevated temperatures and CO2 concentrations. The strains were also evaluated for their carbon capture potential, as well as commercial potential, through biomass analysis. Two strains were identified as cyanobacteria (Leptolyngbya sp. and Pleurocapsa sp.) and two were identified as microalgae (Tetraselmis sp. and Picochlorum maculatum). As cyanobacterial strains in some cases are known to produce toxins, both cyanobacteria were analyzed for presence of genes for cylindrospermopsin, microcystin and saxitoxin production, and found to be negative for all three. All four strains were then cultivated under various temperatures, ranging from 30 to 45˚C. The most productive strain was Tetraselmis sp., with a maximum biomass productivity of 157.7 ± 10.9 mg L-1 d-1 at 30˚C, with a decreasing productivity for increasing temperatures. Leptolygnbya sp. showed an opposite trend, increasing in productivity from 91.4 ± 10.2 to 106.6 ± 7.1 mg L-1 d-1 with increasing temperature from 30 to 40˚C respectively. None of the strains were able to grow at 45 ˚C. The biomass of the four strains cultivated under different temperatures was analyzed for lipid, protein and carbohydrate content, as well as total carbon and nitrogen content. Picochlorum maculatum was found to have the highest lipid and protein content, with 24.0 ± 1.3, 28.0 ± 1.4 and 27.0 ± 1.4 % (w/w) lipids and 21.2 ± 0.2, 23 ± 0.1, and 20 ± 0.9 % (w/w) proteins for cultivation at 30, 35 and 40˚C respectively. This strain also had the highest nitrogen content (12.2 ± 0.05 % at 40˚C) and carbon content (51.2 ± 0.25 % at 45˚C). Compared to Picochlorum maculatum, Tetraselmis sp. showed a slightly lower lipid content (25.6 ± 0.64 and 22.5 ± 0.78% for 30 and 35˚C respectively) and total carbon content (46.9 ± 0.8 and 47.6 ± 0.9% C (w/w) for 30 and 35˚C respectively), however due to the higher productivity, the carbon capture rate for Tetraselmis sp. was the highest of the tested strains, at 270 mg CO2 L-1 d-1 at 30˚C. Pleurocapsa sp. showed the lowest nitrogen content, at 4.4% N (w/w) for 30˚C. There is indication that this strain is capable of fixating atmospheric nitrogen. This is very beneficial for large-scale cultivation, as it reduces the requirements for nitrogen fertilizer, which can greatly reduce costs and improve production sustainability. Furthermore, spectrophotometric analysis of Pleurocapsa sp. and Leptolyngbya sp. showed production of phycobilin proteins, which can have a high commercial value. The tolerance of the strains to increased concentrations of CO2 in the gas phase was also studied for CO2 concentrations ranging from 5% to 30% (v/v). With productivities of 53.7 ± 11.4, 162.2 ± 5.4, 333.8 ± 29.1 and 312.8 ± 12.8 mg L-1 d-1 for 5, 10, 20 and 30% CO2 respectively, Tetraselmis sp. showed that a significant productivity increase could be obtained with increased CO2 concentrations. Picochlorum maculatum showed a similar trend, with slightly lower productivities of 67.1 ± 0.2, 160.5 ± 21.8, 244.1 ± 20.9 and 219.9 ± 15.6 mg L-1 d-1 for 5, 10, 20 and 30% CO2 respectively. Leptolyngbya sp. showed similar productivities for CO2 concentrations ranging from 5-30%, indicating that the strain was not influenced by increasing CO2 concentrations as were the other two strains. Pleurocapsa sp. on the other hand showed no growth at 30% CO2, and stable similar productivities at 5, 10 and 20% CO2. Overall, it can be concluded that for both microalgal strains (Tetraselmis sp. and Picochlorum maculatum) increased CO2 concentrations resulted in a significantly increased productivity, and as of such they would be the most interesting to further investigate for direct coupling to enriched CO2 gas sources, such as industrial flue gasses. Furthermore, besides having the highest productivities of the four investigated strains, Tetraselmis sp. is generally known to have promising characteristics for feed purposes (amino acid profiles and presence of omega-3 fatty acids) as well as for biofuel purposes due to high lipid amounts. Based on these results, Tetraselmis sp. is a very interesting candidate for CO2 capture and production of valuable products in Qatar. Further investigation into this strain is necessary to confirm the presence of such components in this particular strain, as well as to identify conditions which increase specific product productivity, and the capability of direct coupling to industrial flue gas.

There is a lot of interest in the commercial production of microalgae for food applications. Producing marine microalgae in reactors with LED lights has several advantages. Marine microalgae contain valuable components such as antioxidants, and high salinity levels in production systems can prevent contaminations with other organisms. Production in closed systems at different light wavelengths (colours) can result in high biomass concentrations and better control of biomass growth and production of valuable components. Several industries produce salt waste streams, often with associated processing costs. In this report a number of these streams is discussed (liquid fraction of cattle manure biogas slurry, potassium and sodium brines from dairy industries, brackish groundwater, seawater, purge water and brine from salt processing). An option for reducing costs (for disposal or treatment) is the production of marine microalgae on these streams. The algae can be used as food (ingredient). This report describes batch experiments in which growth of nine microalgae species was tested on these waste streams: Nannochloropsis gaditana, Phaeodactylum tricornutum, Tetraselmis chuii (two strains), Porphyridium purpureum, Dunaliella salina, Odontella aurita, Arthrospira platensis and Tetraselmis tetrathele. The experiments were performed in well plates and 1 L reactors with artificial (LED) lights. From the tests it was concluded that several of the algae species can be cultured on different waste streams. The best results were obtained with N. gaditana, A. platensis, P. purpureum en T. chuii (AF&F) on (diluted) brines from the dairy industry and the diluted liquid fraction of biogas slurry. It is recommended to optimize some of these combinations further in experiments. De commerciële kweek van microalgen voor foodtoepassingen staat sterk in de belangstelling. Het kweken van zoutwateralgen in reactoren met LED lampen heeft verschillende voordelen. Zoutwateralgen bevatten waardevolle inhoudsstoffen, zoals antioxidanten, en hoge saliniteit in kweeksystemen kan leiden tot minder contaminatie. Door ze te kweken in gesloten systemen bij verschillende LED lichtgolflengtes (kleuren) kunnen hoge biomassaconcentraties behaald worden en kunnen productie van biomassa en waardevolle inhoudsstoffen gestuurd worden. Vanuit verschillende industrieën komen zoute reststromen vrij, die vaak een negatieve waarde hebben. In dit rapport worden een aantal van deze stromen besproken (dunne fractie digestaat van rundermest, kalium- en natriumpekels van zuivelindustrieën, brak grondwater, zeewater, purgewater en ruwe pekel van zoutwinning). Een mogelijkheid om de kosten (voor lozing of zuivering) te verminderen is de kweek van zoutwateralgen op deze stromen. De algen kunnen gebruikt worden als voeding(singrediënt). Dit rapport beschrijft batchexperimenten waarin de groei van negen verschillende zoutwateralgen getest wordt op de genoemde reststromen. Nannochloropsis gaditana, Phaeodactylum tricornutum, Tetraselmis chuii (twee stammen), Porphyridium purpureum, Dunaliella salina, Odontella aurita, Arthrospira platensis en Tetraselmis tetrathele. De experimenten werden uitgevoerd in wellplaten en 1 L reactoren met kunstlicht. Uit de testen bleken een aantal zoutwateralgen kweekbaar op verschillende reststromen. De best kweekbare algen waren N. gaditana, A. platensis, P. purpureum en T. chuii (AF&F) met name op de (verdunde) pekels uit de zuivelindustrie en de verdunde vloeibare fractie van digestaat. Het verdient aanbeveling om een aantal van deze combinaties verder experimenteel te optimaliseren.

Summary Algal cultures are usually co-cultures of algae and bacteria, especially when considering outdoor mass cultivation. The influence of associated bacteria on algal culture performance has been poorly investigated, although bacteria may strongly affect biomass (or derived product) yield and quality. In this work, the influence on growth and productivity of Tetraselmis suecica F&M-M33 of bacterial communities and single bacterial isolates from the algal phycosphere was investigated. Xenic laboratory and outdoor cultures were compared with an axenic culture in batch. The presence of the bacterial community significantly promoted culture growth. Single bacterial isolates previously found to be strictly associated with T. suecica F&M-M33 also increased growth compared with the axenic culture, whereas loosely associated and common seawater bacteria induced variable growth responses, from positive to detrimental. The increased growth was mainly evidenced as increased algal biomass production and cell size, and occurred after exhaustion of nutrients. This finding is of interest for biofuel production from microalgae, often attained through nutrient starvation processes leading to oil or carbohydrate accumulation. As axenic T. suecica F&M-M33 showed a similar growth with or without vitamins, the most probable mechanism behind bacterial positive influence on algal growth seems nutrient recycling.

Unicellular algae play important roles in the biogeochemical cycles of numerous elements, particularly through the biomineralization capacity of certain species (e.g., coccolithophores greatly contributing to the "organic carbon pump" of the oceans), and unidentified actors of these cycles are still being discovered. This is the case of the unicellular alga Tetraselmis cordiformis (Chlorophyta) that was recently discovered to form intracellular mineral inclusions, called micropearls, which had been previously overlooked. These intracellular inclusions of hydrated amorphous calcium carbonates (ACCs) were first described in Lake Geneva (Switzerland) and are the result of a novel biomineralization process. The genus Tetraselmis includes more than 30 species that have been widely studied since the description of the type species in 1878., The present study shows that many other Tetraselmis species share this biomineralization capacity: 10 species out of the 12 tested contained micropearls, including T. chui, T. convolutae, T. levis, T. subcordiformis, T. suecica and T. tetrathele. Our results indicate that micropearls are not randomly distributed inside the Tetraselmis cells but are located preferentially under the plasma membrane and seem to form a definite pattern, which differs among species. In Tetraselmis cells, the biomineralization process seems to systematically start with a rod-shaped nucleus and results in an enrichment of the micropearls in Sr over Ca (the Sr/Ca ratio is more than 200 times higher in the micropearls than in the surrounding water or growth medium). This concentrating capacity varies among species and may be of interest for possible bioremediation techniques regarding radioactive Sr-90 water pollution., The Tetraselmis species forming micropearls live in various habitats, indicating that this novel biomineralization process takes place in different environments (marine, brackish and freshwater) and is therefore a widespread phenomenon.

Providing a specific pathogen free (SPF) shrimps to the farmers is a big challenge that must be addressed to meet the demand. In general, microalgae are utilized in aquaculture as a live feed for the shrimps. However their importance in the attenuation of negative impacts of pathogenic microbial load, eutrophication and promotion of shrimps growth has to be delineated by experimental investigations to justify the above specific pathogen free shrimps. The present study was carried out to investigate the feeding of five different microalgae and algae enriched Artemia salina. Nauplii on digestive enzyme activity, growth, survival rate, microbial load on Penaeus monodon and Litopenaeus vannamei from Zoea to post larvae (20 stages) and other water quality. Microalgae such as Isochrysis galbana, Cheatoceros calcitrans, Tetraselmis sp, Chlorella sp and Nannochloropsis sp were obtained from AMET Microbial Culture Collection Centre, Department of Marine Biotechnology, AMET University. Penaeus monodon and Litopenaeus vannamei at PL 20 stage showed maximum protease and amylase (digestive enzyme) activity, maximum length and survival rate when fed with Artemia salina Nauplii enriched with C. calcitrans followed by Chlorella sp. On studying the water quality parameters such as, pH, temperature, salinity, dissolved oxygen and ammonia it was found better in tank II where the shrimps were fed with Artemia salina enriched with C. calcitrans. Regarding the vibrio load at different stages of P. monodon and L. vannamei larvae and cultured water it was comparatively lower in tank II where the shrimps were fed with Cheatoceros calcitrans and enriched Artemia salina than other groups.

Direct conversion of microalgae to advanced biofuels with hydrothermal liquefaction (HTL) is an attractive option which has drawn attention in recent years. The presence of heteroatoms in the resultant biocrude, energy input and the process water has been a long-term concern. In this study, the pretreatment of microalgae biomass for protein extraction was conducted prior to HTL for biocrude production. The impact of operating conditions on both the pretreatment and hydrothermal liquefaction steps was investigated. Following HTL using the pretreated algae with an initial solid content of 16% w/w for 30 min at 310 °C, the biocrude yield was 65 wt%, which was more than a 50% improvement in yield as compared to HTL of untreated algae under the same reaction conditions. To achieve a similar biocrude yield using the untreated algae required a much higher reaction temperature of 350 °C. Using recycled process water as reaction media led to a 25 wt% higher biocrude yield. HTL of pretreated algae led to 32–46% nitrogen reduction in resultant biocrude. The biocrude had a higher heating value (HHV) of 28 MJ kg−1 to 34 MJ kg−1. A maximum of 15 wt% protein extract was obtained during pretreatment at 150 °C, 20 min. A similar energy input was required in biocrude production from the untreated route and the combined pretreatment and HTL.

An experimental study was carried out to observe the microbial response to two different plankton-derived organic matter inputs in a coastal sedimentary community of Ubatuba, Sao Paulo, SE Brazil. The organic enrichment experiment was conducted in order to test experimentally the stimulus of the sediment prokaryotic community after the input of labile material simulating an algal bloom reaching the sea floor. A total of 57 corers (two treatments: the diatom Phaeodactylum tricornutun and the phytoflagelate Tetraselmis sp. and a control) were maintained for a total of 30 days in constant temperature, circulation and oxygenation. After the addition of algae an increase in oxygen consumption was observed, accompanied by an increase of prokaryotic total and live density, showing an immediate response from the community to the input of labile material in the sediment. Analyses of molecular fingerprints of bacterial communities by denaturing gel gradient electrophoresis (DGGE) showed differences in bacterial community composition between both treatments and control just after algae addition. This was well evidenced after bacteria genomic libraries analyses that showed differences in diversity and dominance between treatments. In general, Gammaproteobacteria was the most diverse and abundant group in the sediment samples. However, the addition of phytoflagellates led to a shift in dominance in favor of Alphaproteobacteria while diatom input led to a greater bacterial diversity.

Harmful algae may differently affect their primary grazers, causing sub-lethal effects and/or leading to their death. The present study aim to compare the effects of three toxic benthic dinoflagellates on clearance and grazing rates, behavioral changes, and survival of Artemia salina. Feeding assays consisted in 1-h incubations of brine shrimps with the toxic Prorocentrum lima, Gambierdiscus excentricus and Ostreopsis cf. ovata and the non-toxic Tetraselmis sp. Brine shrimps fed unselectively on all toxic and non-toxic algal preys, without significant differences in clearance and ingestion rates. Acute toxicity assays were performed with dinoflagellate cells in two growth phases during 7-h to assess differences in cell toxicity to A. salina. Additionally, exposure to cell-free medium was performed to evaluate its effects on A. salina survival. The behavior of brine shrimps significantly changed during exposure to the toxic dinoflagellates, becoming immobile at the bottom by the end of the trials. Dinoflagellates significantly affected A. salina survival with 100% mortality after 7-h exposure to cells in exponential phase (all treatments) and to P. lima in stationary phase. Mortality rates of brine shrimps exposed to O. cf. ovata and G. excentricus in stationary phase were 91% and 75%, respectively. However, incubations of the brine shrimps with cell-free medium did not affect A. salina survivorship. Significant differences in toxic effects between cell growth phases were only found in the survival rates of A. salina exposed to G. excentricus. Acute exposure to benthic toxic dinoflagellates induced harmful effects on behavior and survival of A. salina. Negative effects related to the toxicity of benthic dinoflagellates are thus expected on their primary grazers making them more vulnerable to predation and vectors of toxins through the marine food webs.

The study was undertaken to know the effect of algal oil as one of the diet ingredients for the betterment of growth, microbial identification and immunological parameters in the fish Daniorerio rerio. The oil was extracted from four micro algae such as Tetraselmis sp., Dunaliella sp., Pavlovasp sp., and Chaetoceros sp., The oil obtained from the four different algae were mixed with other feeding ingredients and fed to Zebra fish Daniorerio rerio. The water quality parameters like temperature, pH, dissolved oxygen, ammonia (NH3), growth parameters such as weight (absolute growth rate, specific growth rate, food conversion ratio), food consumption and food conversion efficiency were studied biochemically in Daniorerio rerio. Bacterial clearance was evaluated and total viable count of bacteria in different parts of the fish such as gut, gill and body surface were enumerated. Among the oil incorporated diet prepared from the four species of microalgae, Tetraselmis sp., had the maximum growth that ranged from 1.34 g to 2.86 g and control had the minimum growth that ranged from 1.14 g to 2.16 g. The maximum food consumption rate recorded in Pavlova sp., was 0.27 g. Among the total protein estimated in 1st, 5th, 10th, 15th, 20th, 25th and 30th days, the maximum protein 6.147 mg/ml was noticed in the fishes which are fed with the feed incorporated with oil obtained from Chaetoceros sp. Among the total lipid estimation in 1st, 5th, 10th, 15th, 20th, 25th and 30th days of feeding, the maximum lipid 6.147 mg/ml was noticed in feed prepared from Dunaliella sp. Among the total carbohydrate estimation in 1st, 5th, 10th, 15th, 20th, 25th and 30th days, the maximum carbohydrate 2.751 mg/ml was noticed in feed Pavlova sp. Among the total carotenoid estimation in 1st, 5th, 10th, 15th, 20th, 25th and 30th days of feeding, the maximum carotenoid 0.70 mg/ml was noticed in the animal they are fed with the diet incorporated with oil obtained from Chaetoceros sp. Among the total bacterial clearance noticed in 1, 2, 3 and 4 hours, the maximum bacterial clearance was noticed in feed having Pavlova sp. oil incorporation after 4 hours. It was found that the Zebra fish fed with the diet incorporated with oil from Tetraselmis sp., gave good growth and pigment production.

The work presented here provides greater insight into the occurrence of the main inorganic elements in algae and how this varies for different species of algae and production methods. It also provides valuable insights into the behavior of algal ashes during combustion, particularly in regard to their interaction with quartz bed material, which is of direct relevance to agglomeration in fluidized bed reactors. A diverse range of algal species was selected for this work using a species of marine microalgae (Tetraselmis sp.) and marine macroalgae (Derbesia tenuissima) and a species of freshwater macroalgae (Oedogonium sp.). Two samples of Oedogonium were tested. One sample was cultivated using a standard nutrient addition regime, and the other was starved of essential nutrients at the completion of the culture cycle. Samples of algae were subject to chemical fractionation and the mode of occurrence of the main inorganic elements was inferred from their leaching behavior. Both the relative proportions of the...

This paper will show the results of a research project about nutrient removal from brines by means of microalgae. This work was a part of a much more ambitious project that searches for possible solutions for management of brines. The objectives of the present research about microalgae were: selection of species for nitrate removal in desalination brines; optimization of control parameters; and determination of possible commercial use. None of the most common species of algae used for industrial culture could be adapted to brine conditions. Spontaneous colonisation of brine by species occurring in the surroundings of the desalination plant provided strains that were finally used in the experiments here presented. In laboratory conditions, the best results were obtained for Tetraselmis seucica illuminated with fluorescent tubes with light period 16–18 h and constant temperature of 22°C. In the outdoor pilot plant Oocystis sp was found the most efficient in nitrate removal (45%) and the most product...

Microalgae harvesting by air flotation is a promising technology for large-scale production of biofuel, feed and nutraceuticals from algae. With an adherence-to-hydrocarbon method and two different types of flotation cells (mechanically agitated cell and Jameson cell), microalgal surface hydrophobicity and bubble size were identified to be critical for effective froth flotation of microalgae. Freshwater alga Chlorella sp. BR2 showed naturally a high hydrophobicity and an ideal response to flotation. However, many marine microalgae possess a low surface hydrophobicity and are thus difficult to harvest. This paper shows that a step-wise optimization approach can substantially improve the flotation of a low surface hydrophobicity marine microalga, Tetraselmis sp. M8, to near full recovery with an enrichment ratio of 11.4.

Marine biota is currently exposed to plastic pollution. The biological effects of plastics may vary according to polymer types (e.g. polystyrene, polyethylene, acrylate), size of particles (macro, micro or nanoparticles) and their shape. There is a considerable lack of knowledge in terms of effects of nanoplastics (NP) to marine biota particularly of polymers like polymethylmethacrylate (PMMA). Thus, this study aimed to assess its ecotoxicological effects using a battery of standard monospecific bioassays with four marine microalgae (Tetraselmis chuii, Nannochloropsis gaditana, Isochrysis galbana and Thalassiosira weissflogii) and a marine rotifer species (Brachionus plicatilis). The tested PMMA-NP concentrations allowed the estimation of median effect concentrations for all microalgae species. T. weissflogii and T. chuii were respectively the most sensitive (EC50,96h of 83.75 mg/L) and least sensitive species (EC50,96h of 132.52 mg/L). The PMMA-NP were also able to induce mortality in rotifers at concentrations higher than 4.69 mg/L with an estimated 48 h median lethal concentration of 13.27 mg/L. A species sensitivity distribution curve (SSD), constructed based on data available in the literature and the data obtained in this study, reveal that PMMA-NP appears as less harmful to marine biota than other polymers like polystyrene.

It is well known that marine microalgae have a high diversity and potency as natural food for aquaculture, a high bioactive compound, and source of biofuel. Tetraselmis sp. is one of the marine-green algae, which has a high lipid content. A completely randomized design was used in this experiment with four levels of temperature treatments (28°C, 30°C, 32°C, and 34°C) and three levels of nitrate treatments (0 gr/L, 0.2 gr/L and 0.4 gr/L) with length of culture was 21 days. The result of our study showed that the highest growth rate was found at 30°C with double nitrate concentration account for 0.20 cell/day. The highest biomass was found at 0.20 g/L nitrate treatment for 34°C temperature treatment account for 0.17 g/L, while the lowest dry weight was 0.08 g/L that was found at 0.0 g/L nitrate treatment for 28°C temperature treatment. The highest free fatty acid percentage was found at 30°C of temperature treatment at the 0.40 g/L of nitrate concentration treatment, account for 8.81 %. Statistically, results showed that increasing temperature affected significantly to biomass and free fatty acid while increasing nitrate was different significantly on growth rate, and biomass.

Photosynthetic unicellular sources contain a large variety of proteins. The types of proteins vary between different microalgae and cyanobacteria. The aim was to study the effect of the variation in proteins and in non-proteinaceous components present in various unicellular protein isolates on their emulsion behavior. Algae soluble protein isolates (ASPIs, 66–77% w/w protein) of Nannochloropsis gaditana, Tetraselmis impellucida and Arthrospira (Spirulina) maxima were studied, using commercially available WPI as a reference (93% w/w protein). All protein isolates could form emulsions stable against creaming (d 3,2 0.2–0.3 μm) at pH 8.0. The amount of each ASPI needed (C cr ; on protein basis) to form these stable emulsions varied between the isolates, but was within the range of proteins from both similar (photosynthetic) sources (algae and sugar beet leaves) and other protein sources (dairy, legume and egg). Minor differences were observed in the pH dependence of flocculation amongst the ASPI stabilized emulsions. For the ASPIs, the expected correlation between interfacial and molecular properties (adsorption rate constant and ζ-potential) and the emulsion behavior (C cr and droplet size as a function of pH) was absent.

Hydrothermal liquefaction (HTL) of microalgae biomass is a promising conversion technology in which wet biomass is treated under high temperature (280–350 °C) and pressure (5–21 MPa), and the associated water in the wet biomass forms the reaction medium. A significant fraction of the microalgae can be converted into biocrude, which separates from the aqueous layer by gravity and/or chemical/mechanical methods. Since the HTL process uses the whole biomass, increasing lipid content during microalgae cultivation is not essential. With an overall goal to utilize highly productive algal strains as feedstocks for liquid hydrocarbon fuel precursors, we investigated the HTL conversion of a marine microalgae (Tetraselmis sp.) in the presence of co-solvents. HTL was performed using a 1.2 L Parr reactor at 275–350 °C for 30 min in the presence or absence of a co-solvent (ethylene glycol and isopropyl alcohol). Results showed that the conversion of Tetraselmis sp. was promoted by higher reaction temperature. The biocrude yield increased from 26.3 ± 1.6% to 31.0 ± 2.1% as the temperature increased from 275 °C to 350 °C. Addition of 10% isopropyl alcohol as co-solvent promoted a 14.5 ± 4.9% increase in biocrude yield and also increased production of gaseous products. In contrast, the use of ethylene glycol as co-solvent did not have a significant effect on biocrude yield. Financial support from Qatar National Priorities Research Program (NPRP grant # 8-646-2-727 from the Qatar National Research Fund) is acknowledged. Steve Kohl and Patrick Hurbain of DRI are acknowledged for their assistance in laboratory analysis. Stephen Spain of University of Nevada, Reno is also acknowledged for his support with FTIR and 1 H NMR analyses . Scopus

Recent focus on algae biomass as an alternative energy source can be attributed to building pressure for conservation of dwindling fossil fuels and reduced greenhouse gas emissions. Both micro- and macroalgae have many advantages over terrestrial plants, including typically faster growth rates and, therefore, higher rates of carbon fixation. This paper reports the combustion characteristics of a species of microalgae and two species of macroalgae under conditions that are relevant for the large-scale use of biomass for heat and other products. The tested species were Tetraselmis sp. (marine microalgae), Derbersia tenusissima (marine macroalgae), and Oedogonium sp. (freshwater macroalgae). Two variants of Oedogonium were tested. One variant was cultivated using standard nutrient additions, and the other variant was starved of essential nutrients. Carbon conversion to CO and CO2 and the release of N as NO were determined for the algae by oxidizing fixed-bed samples of each alga in air at 800 and 1000 °C. Th...

We investigated the effect of the stimulation of bacterial growth on Artemia performance in combination with a standard and with a low algal feeding regime. In both regimes, organic carbon (supplied as sucrose or soluble potato starch) and 15N labeled inorganic nitrogen (supplied as NaNO3) were used to stimulate bacterial growth in the Artemia cultures at C/N ratio 10 and 50. After a culture period of 15 days, significantly improved biomass production was obtained in all treatments with the low algae feeding regime, supplemented by carbohydrate addition. In addition, results of 15N accumulation and fatty acid analysis in Artemia indicated that Artemia utilized more bacteria in algae-limited conditions. Our study shows that bacteria can be used as a nutrient source for Artemia compensating for suboptimal algae supply. In Artemia pond cultures, carbohydrate addition may hence potentially be used to stimulate the conversion of nitrogen waste into heterotrophic bacterial biomass. This can be converted into protein-rich Artemia biomass, especially when algae are in sub-optimal supply. These findings open perspectives for alternative Artemia pond production protocols, in addition to the present management procedures that exclusively focus on phytoplankton blooms as nutrient source to sustain dense Artemia populations.

Four strains of marine microalgae commonly used as live feeds in hatcheries (Isochrysis sp. T.ISO, Tetraselmis suecica, Phaeodactylum tricornutum, Nannochloropsis sp.) were grown in a novel solid-state photobioreactor, the twin-layer system. Microalgae were immobilized by self adhesion to vertically oriented twin-layer modules which consisted of two different types of ultrathin layers, a macroporous source layer (glass fiber nonwoven) through which the culture medium was transported by gravity flow, and a microporous substrate layer (plain printing paper) which carried the algae on both surfaces of the source layer. This simple open cultivation system effectively separated the immobilized microalgae from the bulk of the growth medium and permitted prolonged cultivation of microalgae with average biomass yields of 10–15 g dry weight m−2 growth area after 14–25 days of cultivation. Algal biomass was harvested as fresh weight (with 72–84 % water content) without the need to pre-concentrate algae. No aeration or external CO2 supply was necessary, and due to the microporous substrate layer, no eukaryotic contaminations were observed during the experiment. All experiments were conducted in Germany under greenhouse conditions with natural sunlight. Small-scale growth experiments performed under the same conditions revealed that growth over most of the experimental period (24 days) was linear in all tested algae with growth rates (dry weight per square meter growth area) determined to be 0.6 g m−2 day−1 (Isochrysis), 0.8 g m−2 day−1 (Nannochloropsis), 1.5 g m−2 day−1 (Tetraselmis), and 1.8 g m−2 day−1 (Phaeodactylum). Due to its cost-effective construction and with further optimisation of design and productivity at technical scales, the twin-layer system may provide an attractive alternative to methods traditionally used to cultivate live microalgae.

Mariculture has currently brought greatly valuable products in many fields simultaneously released a large amount of wastewater contributing to water pollutions on account of its organic and inorganic constituents. Nowadays, with the development of environmental engineering, more and more approaches, especially friendly-environmental and highly effective wastewater biological methods, are being applied to tackle pollutions and minimize adverse effects of treatments to reach the sustainable development. This report focuses on the study of proliferation combined with elimination of polluting substances of marine algae species Tetraselmis suiscica, Tetraselmis sp., Platymonas sp. in aq- uaculture wastewater sampled from Can Gio District, Ho Chi Minh City, Vietnam with levels of concentration during 14 days under normal marine algae culture conditions, and compared to that in Daigo’s IMK media. The results shown that, the algae species all grew rapidly simultaneously gave high nutrients removal yields (COD, N, P) and created a considerable amount of biomass within a short period of culture. Particularly, Platomonas sp. and Tetraselmis suiscica could proliferate as well as give high treatment yields of organic substances (COD), PO43-, NO3-, NH4+ and Total Nitrogen in concentrated wastewater. To sum up, this study showed the potential of using microalgae to reduce COD, nitrogen and phosphorus in mariculture wastewater. Ngành nuôi trồng thủy hải sản trong những nằm gần đây đã mang lại nhiều sản phẩm có giá trị trong nhiều lĩnh vực đồng thời thải ra một lượng lớn nước thải gây ô nhiễm nguồn nước bởi các thành phần vô cơ và hữu cơ có trong nước thải. Ngày nay, với sự phát triển của kỹ thuật môi trường, ngày càng nhiều cách tiếp cận, đặc biệt là các phương pháp sinh học hiệu quả cao và thân thiện với môi trường đang được ứng dụng để xử lý ô nhiễm và giảm thiểu hậu quả bất lợi sau xử lý, nhằm hướng tới sự phát triển bền vững. Bài báo cáo tập trung nghiên cứu khả năng sinh trưởng và phát triển của ba loài vi tảo biển Tetraselmis suiscica, Tetraselmis sp., Platymonas sp. kết hợp với việc loại bỏ các hợp chất gây ô nhiễm có trong nước thải từ ao nuôi tôm của huyện Cần Giờ, Việt Nam và so sánh đối chiếu với môi trường dinh dưỡng Daigo’s IMK trong 14 ngày nuôi trồng. Kết quả cho thấy những vi tảo sinh trưởng rất nhanh nhờ vào việc sử dụng các chất ô nhiễm trong nước thải, đặc biệt hiệu suất xử lý COD, PO43-, NO3-, NH4+ và nitơ tổng của Platomonas sp. và Tetraselmis suiscica rất cao thậm chí trong môi trường nước thải đậm đặc. Do đó, chúng tôi kết luận, vi tảo có tiềm năng rất lớn trong việc giảm nồng độ chất hữu cơ, phốt pho và nitơ trong nước thải nuôi trồng thủy hải sản., Journal of Vietnamese Environment, Vol 8 No 2 (2016)

In the wake of intensive fossil fuel usage and CO2 accumulation in the environment, research is targeted toward sustainable alternate bioenergy that can suffice the growing need for fuel and also that leaves a minimal carbon footprint. Oil production from microalgae can potentially be carried out more efficiently, leaving a smaller footprint and without competing for arable land or biodiverse landscapes. However, current algae cultivation systems and lipid induction processes must be significantly improved and are threatened by contamination with other algae or algal grazers. To address this issue, we have developed an efficient two-stage cultivation system using the marine microalga Tetraselmis sp. M8. This hybrid system combines exponential biomass production in positive pressure air lift-driven bioreactors with a separate synchronized high-lipid induction phase in nutrient deplete open raceway ponds. A comparison to either bioreactor or open raceway pond cultivation system suggests that this process potentially leads to significantly higher productivity of algal lipids. Nutrients are only added to the closed bioreactors, while open raceway ponds have turnovers of only a few days, thus reducing the issue of microalgal grazers.

RESUMEN. Algas y microalgas son productoras de compuestos antioxidantes como respuesta protectora al daño producido por estrés (radiación UV, variación de temperatura, iluminación excesiva, entre otros). En el presente estudio, se evaluó en condiciones de laboratorio el contenido de fenoles totales en cuatro especies de microalgas marinas: Chaetoceros muelleri (Lemmermann, 1898), Thalassiosira weissflogii (Grunow, 1977), Dunaliella tertiolecta (Butcher, 1959) y Tetraselmis chuii (Butcher, 1959), sometidas a diferentes condiciones de iluminación por efecto del material de las unidades de cultivo (recipientes de vidrio transparente y de plástico azul). Los fenoles totales fueron extraídos y se cuantificaron mediante espectrofotometría. Independiente de la condición de iluminación, el mayor número de células se encontró en D. tertiolecta y C. muelleri con 904.000 y 965.000 cél mL-1, respectivamente. La concentración de fenoles totales (mgEAG g-1 peso seco) fue diferente entre especies; sin embargo, no se encontraron diferencias significativas respecto a la condición de iluminación. Los extractos de D. tertiolecta cultivada en vidrio y T. chuii cultivada en plástico, mostraron el mayor contenido de fenoles (1,54 y 1,52 mgEAG g-1 peso seco, respectivamente). Se concluye que la producción de compuestos fenólicos fue mayor en los cultivos con microalgas verdes, independientemente de la condición de iluminación.

Micro algae are a diverse group of aquatic, photosynthetic organisms which are the primary food source for many crustaceans, molluscs and fish species occurring naturally in the marine food chain. In the recent past, micro algae have shown great importance as food supplements not just for the marine Eco system but for the cattle - poultry feed stocks as well as the human beings. Micro algae render most of the essential nutrients such as amino acids, proteins, sugars, fatty acids, vitamins etc. which will supplement and provide a balanced mixture of nutrients to the animals there by enhancing the quality of eggs, meat, fish meat and other co products. 50 strains of micro algae that can be potentially useful for the food security program were screened from QUCCM (Qatar University Culture Collection of Cyanobacteria and Micro algae) for their biochemical composition.Following the screening process,10 eminent strains such as Chlorella sp, Nannochloris sp, Tetraselmis sp, Desmodesmus sp, Myconastes sp, Chlamydomonas sp, Scenedesmus sp, Chlrococcum sp, Ourococcus sp, Chlorocystis sp representing major micro algal taxa were chosen whose protein content was estimated to be (20–45%) and carbohydrates (8–20%) that may best be adapted to Qatar's environmental conditions. Proteins are composed of different amino acids and hence the nutritional quality of a protein is determined basically by the content, proportion and availability of its amino acids. Therefore, Amino acid profiling was also performed for few selected strains using the method adapted from Heinrikson and Meredith 1984 and quantified by HPLC using UV detector. The profiles obtained for some of the strains showed similarity and richness in all the essential amino acids particularly high in glycine, serine, aspartate and glutamate. On the other hand, the micro algal polysaccharides extracted by acid hydrolysis was quantified using HPLC coupled with RI detector. The profiles exhibited variability in sugar compositions showing the presence of mainly glucose, fructose and xylose in different amounts. Above all, most of the strains displayed a reasonably fair growth rate (0.2–1.5 per day approx.) which further supports algae being used as feed by attaining more mass in lesser time.Therefore it was highlighted that micro algae have a very diverse profile for metabolites under standard growth conditions. Chlorella sp was rich in its protein content while Chlorocystis sp exhibited its importance in sugars. The presence of all essential amino acids in microalgae helps fulfill the missing nutritional requirements in animals and humans. Micro algae are able to enhance the nutritional content of conventional food preparations and therefore positively affect the life of organisms consuming it. Based on the available information on toxic properties or any other adverse effects of algae, none of the them caused any anomalies on feeding experiments during various toxicity tests making them completely safe for use as feed (Chamorro, 1980). It can be concluded that microalgae have an important role in food security and the nutritional profiles of Qatari isolates closely matched the overseas strains. A segment of World algal production can be used for animal feed application and aquaculture.KeywordsMicroalgae, Protein, Carbohydrate, Amino acids, Amino acid profiling, HPLC