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Information on the nutritional requirements and preferred diets of sea cucumber juveniles is extremely limited and this has hindered development of hatchery culture methods. This study assessed ingestion, cell wall digestion and relative nutritional values of two live micro-algae (Isochrysis aff. galbana (TISO) and Chaetoceros muelleri) and six concentrated micro-algae products (Instant Algae®, Reed Mariculture Inc.) for early juveniles of sandfish, Holothuria scabra. Seven of the eight micro-algae tested were ingested by juveniles with the exception of live TISO. Faeces excretion times varied between ingested diets that passed through the juvenile gut in less than 1 h. The cell walls of five of the eight micro-algae tested were partially or mostly digested (Chaetoceros muelleri, TW1200®, Palova 1800®, Isochrysis 1800® and Shellfish 1800®), while the cell walls of Tetraselmis 3600® and 3H 1800® remained intact. Juvenile growth rates were significantly different between diet treatments over the duration of a 14 day growth trial. Mean (± SE) length of early juveniles at the end of the growth trial was highest for those fed live C. muelleri (4.10 ± 0.03 mm) followed by TW 1200® (3.49 ± 0.05 mm). Juvenile survival did not differ significantly between diet treatments and was highest for those fed C. muelleri (79.33 ± 6.11%) followed by TW1200® (78.33 ± 1.20%). Pearson's correlation tests were used to identify key correlations between the levels of specific nutrients and juvenile performance (growth and survival). A significant positive correlation between growth and dietary protein content (P < 0.05), and a highly significant positive correlation between growth and dietary EPA:DHA ratio (P < 0.01) provide new information to inform diet selection for juvenile sandfish that will help improve juvenile performance and support improved hatchery production. Use of commercially available micro-algae concentrates as a replacement for live micro-algae in sandfish hatcheries supports development of cheaper, simpler post settlement rearing protocols for this species.

Knowledge of ingestion and digestion of micro-algae by bivalve larvae is critical for provision of appropriate larval nutrition supporting maximal growth and survival. However, little is known about the ingestion and digestion of micro-algae by giant clam larvae. This study determined the rates of ingestion and digestion of commercially available micro-algae concentrates by Tridacna noae larvae of different ages using epifluorescence microscopy. The micro-algae used were Isochrysis sp. (Isochrysis 1800®), Pavlova sp. (Pavlova 1800®), Tetraselmis sp. (Tetraselmis 3600®) and Thalassiosira weissflogii (TW 1200®). None of the four micro-algal concentrates were ingested by T. noae larvae at 24 h post-fertilisation, but all were ingested at 48 h and 72 h post-fertilisation, at different frequencies. At 48 h post-fertilisation, Isochrysis sp. and Pavlova sp. were ingested by 77% and 70% of veligers, respectively, while T. weissflogii and Tetraselmis sp. were ingested by 10% and 30% of veligers, respectively. Similar rates of ingestion were observed for each micro-alga by larvae at 72 h post-fertilisation. Larvae capable of ingesting micro-algae concentrates were significantly larger than those that were empty and the minimum antero-posterior shell length of T. noae larvae capable of ingesting Pavlova sp. and Isochrysis sp. was 141 μm and 132 μm, respectively. Digestion of micro-algae by 48 h-veligers was observed 2 h after the start of feeding in 26.1% and 14.3% of larvae that had ingested Isochrysis sp. and Pavlova sp., respectively, but digestion of Tetraselmis sp. and T. weissflogii was not observed until 4 h and 8 h after the start of feeding, respectively. Complete digestion of Pavlova sp. and Isochrysis sp. took up to 12 h in larvae at both 48 h and 72 h post-fertilisation. Our results provide a basis for developing a more nutritionally informed approach to hatchery culture of T. noae.

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.

Biofouling is a global problem that affects virtually all the immersed structures. Currently, several novel environmentally friendly approaches are being tested worldwide to decrease the toxicity of biocides in non-fouling species, such as the encapsulation/immobilization of commercially available biocides, in order to achieve control over the leaching rate. The present study addresses the toxicity of two widely used booster biocides, zinc pyrithione (ZnPT) and copper pyrithione (CuPT), in its free and incorporated forms in order to assess their toxicity and anti-fouling efficacy in target and non-target species. To achieve this goal, the following marine organisms were tested; the green microalgae Tetraselmis chuii (non-target species) and both target species, the diatom Phaeodactylum tricornutum and the mussel Mytilus edulis. Organisms were exposed to both biocides, two unloaded nanostructured materials and nanomaterials loaded with biocides, from 10 μg/L to 100 mg/L total weight, following standard protocols. The most eco-friendly and simultaneously efficient anti-fouling solution against the two photosynthetic species (nanoclays loaded with ZnPT) was then tested on mussels to assess its lethal efficacy (LC50 = 123 μg/L) and compared with free biocide (LC50 = 211 μg/L) and unloaded material (LC50 > 1000 μg/L). A second exposure test with sub-lethal concentrations (lower than 100 μg/L), using mussels, was carried out to assess biochemical changes caused by the tested compounds. Oxidative stress, detoxification and neurotransmission markers were not responsive; however, different antioxidant patterns were found with free ZnPT and loaded nanoclay exposures. Thus, the immobilization of the biocide ZnPT into nanoclays proved to be a promising efficient and eco-friendly anti-fouling strategy.

Feeding copepods during early larval culture stages of marine fish has proven to be advantageous for growth and survival of marine finfish larvae. However, commercial availability of most copepods is limited; thus, there is an impetus to evaluate promising copepod species to meet the diverse dietary demands of various marine fish. The marine cyclopoid copepod, Oithona colcarva, was isolated out of zooplankton samples taken from waters within Tampa Bay, Florida. Once isolated, trials were conducted to determine the appropriate culture parameters for producing nauplii to feed marine fish larvae. The effects of temperature (22°C, 26°C and 30°C), salinity (15, 20, 25, 30 and 35 g L−1), stocking density (0.5, 1.0, 2.0, 4.0 and 8.0 individuals mL−1) and diet (Nanno 3600 microalgae paste, Colurella adriatica, Rhodomonas lens, Tisochrysis lutea, Chaetoceros gracilis and/or Tetraselmis chuii) on nauplii production during a single life cycle of reproducing individuals were examined. Results of those trials indicated that a culture temperature of 30°C and a salinity of 30 g L−1 were advantageous for maximum nauplii production. Furthermore, a diet containing a 1:1:1 mixture of T. lutea, C. gracilis and T. chuii and a stocking density of at least 8 individuals mL−1 were identified as beneficial. The results of these trials, the potential for large-scale culture and observations on the performance of marine fish larvae fed Oithona colcarva nauplii are discussed.

In this study, it has aimed that Nannochloropsis oculata, Tetraselmis chuii, and Dunaliella salina microalgae species were examined effects on growth in different salinity and to determine the optimum salinity concentration for the culture. Cultures were growth in flask enriched with F/2 medium arranged to be pH 8 as culture temperature to be 22±2ºC and were performed in triplicate. In different salinity concentration, the highest cell density for Nannochloropsis oculata was obtained at ‰20 between ‰30 concentrations of salinity, for Tetraselmis chuii the highest cell density was determined at ‰30 and ‰40 concentrations of salinity. For Dunaliella salina microalga, the highest cell density was obtained at ‰40 concentrations of salinity.

Recently, microalgae have been attracting a wide attention as a source of high-lipid feedstock to produce biodiesel. A total of twenty one halophilic microalgae were isolated from the hypersaline Bardawil lagoon North Sinai, Egypt. Nine of them were further characterized with respect to biomass and fatty acid productivities. Biomass productivity as cellular dry weight (CDW), fatty acid content and, consequently, fatty acid productivity of the chlorophyte Tetraselmis elliptica was the highest among alltested strains (0.122 g CDW L−1 d−1, 77.36 mg g−1 CDW and 14.1 mg L−1 d−1, respectively). Lipid fractionation showed that total lipids represented 12.96 mg g−1 CDW and neutral lipids represented 37% of the total lipids with corresponding iodine value of 70.3 g I2/100 g oil. In all fractions, C16:0 and C18:1n-9 were predominant, being as high as 31 and 20% of total fatty acids in neutral lipids, 26 and 24% of total fatty acids in polar lipids and 28 and 26% of total fatty acids in phospholipids, respectively. This study demonstrates that the halophilic microalga T. elliptica isolated from hypersaline water is a promising species for biodiesel feedstock.

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.

Photosynthetic unicellular organisms are considered as promising alternative protein sources. The aim of this study is to understand the extent to which these green sources differ with respect to their gross composition and how these differences affect the final protein isolate. Using mild isolation techniques, proteins were extracted and isolated from four different unicellular sources (Arthrospira (spirulina) maxima, Nannochloropsis gaditana, Tetraselmis impellucida, and Scenedesmus dimorphus). Despite differences in protein contents of the sources (27-62% w/w) and in protein extractability (17-74% w/w), final protein isolates were obtained that had similar protein contents (62-77% w/w) and protein yields (3-9% w/w). Protein solubility as a function of pH was different between the sources and in ionic strength dependency, especially at pH < 4.0. Overall, the characterization and extraction protocol used allows a relatively fast and well-described isolation of purified proteins from novel protein sources.

We report here the first mitogenome sequences for the chlorophyte class Chlorodendrophyceae. The mitogenomes of Tetraselmis sp. CCMP 881 and Scherffelia dubia (SAG 17.86) are 46,904 bp and ...

Pada ekosistem air, mikroalga merupakan penghasil alami energi dan senyawa metabolit potensial. Mikroalga ekstraseluler memiliki fungsi sebagai penghambat dan memicu pertumbuhan senyawa. Tetraselmis chuii memiliki komponen bioaktif seperti asam lemak dan ester yang digunakan sebagai agen antibakteri. Antimikroba adalah senyawa yang dapat menghambat pertumbuhan mikroba. Proses ekstraksi dipengaruhi oleh metode ekstraksi, berbagai pelarut, dan kondisi ekstraksi. Tujuan penelitian ini adalah untuk mendapatkan informasi tentang penggunaan berbagai pelarut dan ekstraksi siklus total terhadap hasil ekstrak Tetraselmis chuii, mengetahui aktivitas antimikroba ekstrak Tetraselmis chuii terhadap S. aureus, E. coli, A. flavus dan C. Albicans, dan mengidentifikasi senyawa bioaktif ekstrak Tetraselmis chuii yang bertindak sebagai agen antimikroba dengan menggunakan metode GC-MS. Hasil penelitian menunjukkan bahwa rendemen tertinggi dihasilkan dari pelarut aseton pada 3 siklus ekstraksi, yaitu sebesar 35.19%. Uji aktivitas antimikroba terbaik menghasilkan ekstrak dari pelarut kloroform dengan ekstraksi 3 siklus dengan diameter zona hambatan 16.43 mm pada S.aureus, 16.07 mm pada E. coli, 15.46 mm di C. albicans, dan 15.8 mm di A.flavus. Senyawa bioaktif dari ekstrak Tetraselmis chuii berpotensi sebagai senyawa antimikroba, termasuk asam lemak, ester, alkohol, keton, benzene, dan alkana.

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.

Background Caulerpa lentillifera is one of the most important economic green macroalgae in the world. Increasing demand for consumption has led to the commercial cultivation of C. lentillifera in Japan and Vietnam in recent decades. Concomitant with the increase of C. lentillifera cultivation is a rise in disease. We hypothesise that epiphytes or other microorganisms outbreak at the C. lentillifera farm may be an important factor contributing to disease in C. lentillifera. The main aims are obtaining differences in the microbial community structure and diversity between healthy and diseased C. lentillifera and key epiphytes and other microorganisms affecting the differences through the results of high-throughput sequencing and bioinformatics analysis in the present study. Results A total of 14,050, 2479, and 941 operational taxonomic units (OTUs) were obtained from all samples using 16S rDNA, 18S rDNA, and internal transcribed spacer (ITS) high-throughput sequencing, respectively. 16S rDNA sequencing and 18S rDNA sequencing showed that microbial community diversity was higher in diseased C. lentillifera than in healthy C. lentillifera. Both PCoA results and UPGMA results indicated that the healthy and diseased algae samples have characteristically different microbial communities. The predominant prokaryotic phyla were Proteobacteria, Planctomycetes, Bacteroidetes, Cyanobacteria, Acidobacteria, Acidobacteria and Parcubacteria in all sequences. Chlorophyta was the most abundant eukaryotic phylum followed by Bacillariophyta based on 18S rDNA sequencing. Ascomycota was the dominant fungal phylum detected in healthy C. lentillifera based on ITS sequencing, whereas fungi was rare in diseased C. lentillifera, suggesting that Ascomycota was probably fungal endosymbiont in healthy C. lentillifera. There was a significantly higher abundance of Bacteroidetes, Cyanobacteria, Bacillariophyta, Ulvales and Tetraselmis in diseased C. lentillifera than in healthy C. lentillifera. Disease outbreaks significantly change carbohydrate metabolism, environmental information processing and genetic information processing of prokaryotic communities in C. lentillifera through predicted functional analyses using the Tax4Fun tool. Conclusions Bacteroidetes, Cyanobacteria, Bacillariophyta, Ulvales and Tetraselmis outbreak at the C. lentillifera farm sites was an important factor contributing to disease in C. lentillifera.

In this study, a new electrocoagulation electrode configuration has been investigated in order to induce dielectrophoretic (DEP) force for the enhanced harvesting of marine microalgae (Tetraselmis sp.). Asymmetrical aluminum electrodes with an alternative current power supply were used. The impact of electrode configuration, current density and electrolysis time were evaluated. A maximum algal harvesting efficiency of 90.9% was achieved using 7.1 mA/cm2 current density and 10 min electrolysis time. The energy consumption was found to be 4.62 kWh/kg of microalgae. The major significance of using the new electrode configuration was found in the aluminum content in the harvested biomass which decreased by 52% compared to the conventional symmetrical electrocoagulation electrodes. 2020 Elsevier Ltd The authors would like to thank Qatar University for the provided financial support. The authors would also like to thank the Center for Sustainable Development at Qatar University for providing the marine microalgae species. Scopus

Wastewater treatment, along with the simultaneous production of valuable chemical compounds, including lipids by microalgae is a challenging but attractive study. Towards this goal, the candidate microalgae were selected from culture collections or isolated from wastewater in this study. The initial screening test using microalgae revealed that various eukaryotic as well as prokaryotic microalgae showed steady growth in municipal wastewater samples. Among them, Tetraselmis sp. NKG400013 and Parachlorella kessleri NKG021201 from culture collections, and Chloroidium saccharophilum NKH13 from the wastewater sample exhibited high biomass productivity. Furthermore, P. kessleri NKG021201 and C. saccharophilum NKH13 showed high lipid productivity (56 ± 1 mg/L/day for NKG021201, 35 ± 10 mg/L/day for NKH13). During this cultivation, 99% of nitrogen and 82% of phosphorous compounds were removed from the wastewater sample by the strain NKG021201. Analysis of fatty acid compositions of P. kessleri NKG021201 and C. saccharophilum NKH13 revealed that lipids derived from these microalgae were suitable for the application of biodiesel fuels, indicating that these microalgae were promising for wastewater treatment and lipid production.

Both enzymatic or oxidative carotenoids cleavages can often occur in nature and produce a wide range of bioactive apocarotenoids. Considering that no detailed information is available in the literature regarding the occurrence of apocarotenoids in microalgae species, the aim of this study was to study the extraction and characterization of apocarotenoids in four different microalgae strains: Chlamydomonas sp. CCMP 2294, Tetraselmis chuii SAG 8-6, Nannochloropsis gaditana CCMP 526, and Chlorella sorokiniana NIVA-CHL 176. This was done for the first time using an online method coupling supercritical fluid extraction and supercritical fluid chromatography tandem mass spectrometry. A total of 29 different apocarotenoids, including various apocarotenoid fatty acid esters, were detected: apo-12&rsquo, zeaxanthinal, &beta, apo-12&rsquo, carotenal, apo-12-luteinal, and apo-12&rsquo, violaxanthal. These were detected in all the investigated strains together with the two apocarotenoid esters, apo-10&rsquo, zeaxanthinal-C4:0 and apo-8&rsquo, zeaxanthinal-C8:0. The overall extraction and detection time for the apocarotenoids was less than 10 min, including apocarotenoids esters, with an overall analysis time of less than 20 min. Moreover, preliminary quantitative data showed that the &beta, apo-8&rsquo, carotenal content was around 0.8% and 2.4% of the parent carotenoid, in the C. sorokiniana and T. chuii strains, respectively. This methodology could be applied as a selective and efficient method for the apocarotenoids detection.

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 endocrine-disrupting chemical bisphenol A (BPA) has attracted much attention because of its estrogenic activity and widespread environmental contamination. In this study, we investigated the BPA biodegradation abilities of various bacterial strains isolated from deserts and arid soils from southern Tunisia. Ten bacterial strains that belong to Pseudomonas putida, Pseudomonas aeruginosa, Enterobacter cloacae, Klebsiella sp. and Pantoea sp. showed high BPA removal potential in mineral salt medium (MSM) containing 1 mM BPA. BPA removal rates varied between strains and ranged from 36 to 97%. The strain G320 (P. putida) presented the highest BPA removal rate with 97% within 4 days at 30 °C. The half-life when increasing the BPA concentration to 3 mM was 2 days for strain G320, while total degradation was achieved within 8 days. BPA biodegradation products were identified by GC–MS, and their toxicity was assessed by an algal toxicity test. BPA detoxification was confirmed by evaluating the effect of its biodegradation metabolites on algal growth (dry weight), cells morphology and chlorophylls levels of Tetraselmis sp. strain V2. Results showed the interesting potential of desert soil’s bacteria in BPA detoxification as well as the eventual use of the algal specie in toxicity assessment. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13205-019-1756-y) contains supplementary material, which is available to authorized users.

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.

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

Tetraselmis desikacharyi is a marine alga, known as an important plankton for aquaculture as a feed organism. However, the genomic study on this class is rare. Here, we present a complete Chlorodendrophyceae chloroplast genome of T. desikacharyi, belonging to Chlorodendrophyceae with a full length of 149,934bp, characterized by a very small single-copy (SSC) region without any genes and a large inverted repeat (IR) region. A maximum-likelihood (ML) phylogenetic analysis was performed using three kinds of data comprising 50 protein-coding genes, which placed the Chlorodendrophyceae as a deep-diverging lineage of the core Chlorophyta.nnT. desikacharyi, characterized by their intense green colored chloroplast, is important for aquaculture as a feed organism, and for studying plankton growth cycles due to their fast growth rate (Arora et al., 2013; Norris et al., 1980). However, only two chloroplast genomes have been published in ...

Microalgae are currently considered one of the most promising resources for biofuel production, aquaculture feedstock and new pharmaceuticals. Among them, green algae of the genus Tetraselmis are extensively studied for their lipid accumulation in nutrient-starvation conditions. In this paper, we present the full-transcriptome of Tetraselmis suecica and differential expression analysis between nitrogen-starved and -repleted conditions (at stationary phase) focusing not only on lipid metabolism but giving new insights on nutrient starvation responses. Transcripts involved in signal transduction pathways, stress and antioxidant responses and solute transport were strongly up-regulated when T. suecica was cultured under nitrogen starvation. On the contrary, transcripts involved in amino acid synthesis, degradation of sugars, secondary metabolite synthesis, as well as photosynthetic activity were down-regulated under the same conditions. Among differentially expressed transcripts, a polyketide synthase and three lipoxygenases (involved in the synthesis of secondary metabolites with antipredator, anticancer and anti-infective activities) were identified, suggesting the potential synthesis of bioactive compounds by this microalga. In addition, the transcript for a putative nitrilase, enzyme used in nitrile bioremediation, is here reported for the first time for T. suecica. These findings give new insights on T. suecica responses to nutrient starvation and on possible biotechnological applications for green algae.

The widespread use of microplastics and nanomaterials resulting in environmental contamination is of high concern. Microplastics have been found to modulate the toxicity of other environmental contaminants. Thus, the hypothesis that microplastics increase the toxicity of gold nanoparticles to the marine microalgae Tetraselmis chuii was tested. In a laboratory bioassay, T. chuii cultures were exposed for 96 h to ∼5 nm diameter gold nanoparticles (AuNP) and to virgin 1–5 μm diameter microplastics (MP), alone and in mixture. The treatments were: control; citrate-control; AuNP alone (0.1, 0.3 and 3 mg/L); MP alone (0.3, 0.9 and 4 mg/L) and mixture of the two substances in three different concentrations (0.1 mg/L AuNP + 0.3 mg/L MP; 0.3 mg/L AuNP + 0.9 mg/L MP; 3 mg/l AuNP + 4 mg/L MP). The effect criterion was the inhibition of the average specific growth rate. AuNP alone and MP alone did not cause significant decrease of T. chui average specific growth rate up to 3 mg/L and 4 mg/L, respectively. The mixture containing 3 mg/L AuNP + 4 mg/L MP significantly reduced the average specific growth rate of the microalgae. Therefore, this mixture was more toxic to T. chuii than its components individually. Overall, the results of the present study indicated that the MP and AuNP tested have a relatively low toxicity to T. chuii, but the toxicity increases when they are in mixtures containing high concentrations of both substances. These proof-of-concept findings stress the need of more research on the toxicity of mixtures containing microplastics and nanomaterials.

Marine microalgae constitute a natural source of compounds (e.g., alkanes, triacylglycerols) useful for biodiesel production—yet improvement of lipid productivity by microalgae is a sine qua non for the economic feasibility of such a microalga-based process. Toward this goal, five Tetraselmis strains, Tetraselmis suecica UW605, T. suecia AROSA, and three Tetraselmis sp. strains, coded as lipogenic (63LG and 75LG) or non-lipogenic (46NLG) on the basis of stationary-phase cell flotation features, were cultured semi-continuously and subjected to 10 and 30% renewal rates; the effects upon growth rate and lipidic profile were accordingly assessed. As expected, cell productivity by all strains was higher under a renewal rate of 30%. Chlorophyll, protein, and total lipid content per cell also increased with the highest renewal rate. Conversely, cell content of neutral lipids, measured with Nile red staining, decreased with increasing renewal rate. The non-lipogenic strain 46NLG revealed a much lower total lipid content, at the 10% renewal rate, than all other strains, but a higher neutral lipid content. This result supports the use of the flotation method for the selection of lipogenic strains. The diverse profiles of the various Tetraselmis strains and the effect of renewal rate on their neutral lipid content emphasize the importance of strain screening to promote a suitable microalgae selection for biodiesel production purposes.

The present work uncovers a potentially ancient but yet undescribed biomineralization process, in which unicellular planktonic eukaryotes produce multiple intracellular inclusions of near-amorphous calcium carbonate (ACC), called micropearls. This process is not linked to a specific habitat and occurs in multiple areas around the world in marine, brackish and freshwater environments. This unsuspected biomineralization capacity was discovered to be common in the Tetraselmis genus (Chlorodendrophyceae, Chlorophyta). In these organisms, the micropearls may be slightly enriched in strontium and their arrangement forms a pattern (alignements linked to the chloroplast shape), which is characteristic for a given species. Another organism forming micropearls highly enriched in barium was detected in Lake Geneva (Switzerland). It is still unidentified, but might belong to the zooplankton. All the micropearls seem to result of a biologically controlled process. They represent a new physiological feature for eukaryotes.

Commercial production of microalgal biomass for food and feed is a recent worldwide trend. Although it is common to publish nutritional data for microalgae grown at the lab-scale, data about industrial strains cultivated in an industrial setting are scarce in the literature. Thus, here we present the nutritional composition and a microbiological and toxicological evaluation of Tetraselmis sp. CTP4 biomass, cultivated in 100-m3 photobioreactors at an industrial production facility (AlgaFarm). This microalga contained high amounts of protein (31.2 g/100 g), dietary fibres (24.6 g/100 g), digestible carbohydrates (18.1 g/100 g) and ashes (15.2 g/100 g), but low lipid content (7.04 g/100 g). The biomass displayed a balanced amount of essential amino acids, n-3 polyunsaturated fatty acids, and starch-like polysaccharides. Significant levels of chlorophyll (3.5 g/100 g), carotenoids (0.61 g/100 g), and vitamins (e.g., 79.2 mg ascorbic acid /100 g) were also found in the biomass. Conversely, pathogenic bacteria, heavy metals, cyanotoxins, mycotoxins, polycyclic aromatic hydrocarbons, and pesticides were absent. The biomass showed moderate antioxidant activity in several in vitro assays. Taken together, as the biomass produced has a balanced biochemical composition of macronutrients and (pro-)vitamins, lacking any toxic contaminants, these results suggest that this strain can be used for nutritional applications. Agência financiadora Fundação para a Ciencia e a Tecnologia (FCT) UID/Multi/04326/2019 ALGARED+ 5E - INTERREG V-A Espana-Portugal project 0055 Fundacao para a Ciencia e a Tecnologia (FCT) SFRH/BD/105541/2014 SFRH/BPD/81882/2011 SFRH/BPD/100627/2014 CI-ECO - POCI-01-0145-FEDER-007679 FCT UID/CTM/50011/2013 Q-PNA - FCT UID/QUI/00062/2013 info:eu-repo/semantics/publishedVersion

To assess the influence of food type on biomarkers, mussels (Mytilus galloprovincialis) were maintained under laboratory conditions and fed using 4 different microalgae diets ad libitum for 1 week: (a) Isochrysis galbana; (b) Tetraselmis chuii; (c) a mixture of I. galbana and T. chuii; and (d) a commercial food (Microalgae Composed Diet, Acuinuga). Different microalgae were shown to present different distribution and fate in the midgut. I. galbana (approximate to 4 mu m empty set) readily reached digestive cells to be intracellularly digested. T. chuii (approximate to 10 mu m empty set and hardly digestible) was retained in stomach and digestive ducts for long times and extracellularly digested. Based on these findings, it appeared likely that the presence of large amounts of microalgal enzymes and metabolites might interfere with biochemical determinations of mussel's biomarkers and/or that the diet-induced alterations of mussels' digestion could modulate lysosomal and tissue-level biomarkers. To test these hypotheses, a battery of common biochemical, cytological and tissue-level biomarkers were determined in the gills (including activities of pyruvate kinase, phosphoenolpyruvate carboxykinase and cytochrome c oxidase) and the digestive gland of the mussels (including protein, lipid, free glucose and glycogen total content, lysosomal structural changes and membrane stability, intracellular accumulation of neutral lipids and lipofuscins, changes in cell type composition and epithelial thinning, as well as altered tissue integrity). The type of food was concluded to be a major factor influencing biomarkers in short-term experiments though not all the microalgae affected biomarkers and their responsiveness in the same way. T. chuii seemed to alter the nutritional status, oxidative stress and digestion processes, thus interfering with a variety of biomarkers. On the other hand, the massive presence of I. galbana within digestive cells hampered the measurement of cytochemical biomarkers and rendered less reliable the results of biochemical biomarkers (as these could be attributed to both the mussel and the microalgae). Research to optimize dietary food type, composition, regime and rations for toxicological experimentation is urgently needed. Meanwhile, a detailed description of the food type and feeding conditions should be always provided when reporting aquatic toxicological experiments with mussels, as a necessary prerequisite to compare and interpret the biological responses elicited by pollutants. This work was funded by the Spanish Ministry of Economy and Finance (BMW-CTM2012-40203-C02-01), the University of the Basque Country UPV/EHU (UFI 11/37) and the Basque Government (Consolidated Research Groups Grant IT810-B). EB-R was recipient of a doctoral fellowship (PRE2013 1 640) financed by the Department of Education of the Basque Government (Eusko Jaurlaritza).

Summary: Biomass and metabolite production of three marine (Tetraselmis sp., Nannochloropsis sp., Chlorocystis sp.) and three freshwater microalgae (Scenedesmus sp., Chlorella sp., Monoraphidium sp.) were studied under different iron concentrations. The biomass concentration in control cultures (i.e., no iron added) was in the range of 291.5 707.5 mg/L, suggesting that these microalgae could use dissolved iron in the source water and also the carried over iron from the inoculum. In terms of biomass production, 0.05 mg/L or less Fe3+ supplementation was optimum for all the marine microalgae, however addition of iron did not have any significant effect on the biomass yield of freshwater microalgae (P < 0.05). Different iron supplementations, however, resulted in mixed trends in metabolites contents among these strains. Nevertheless, iron uptake by these microalgae was low while extra iron could remain in the culture media or precipitate. The biomass concentrations of Nannochloropsis sp. and Scenedesmus sp. cultures, when grown in outdoor 1000 L raceway tanks without iron supplementation, were 721.5 mg/L and 530 mg/L, respectively. From the indoor and outdoor experiments, it can be concluded that some microalgae have a very low iron requirement. Scopus

A halo-tolerant Tetraselmis sp. was grown in a 100,000 L raceway pond in the Qatari desert environment. As the biomass density reached 0.679 g/L, after 7 days, five different harvesting methods (i.e., cross-flow filtration, electrocoagulation, and coagulation-flocculation by FeCl3, NaOH, and alum) were applied to harvest the biomass. Hydrothermal liquefaction, for all the harvested biomass, was conducted at 350 °C for 30 mins in 10 mL Swagelok unions. The biocrude yield from cross-flow processed biomass (i.e., control) was 50.8%. Biocrude yield from electrocoagulation and alum processed biomass were 62.7% and 60.4% respectively where aluminum could have a catalytic effect. Biocrude yield from FeCl3 and NaOH processed biomass were 42.9% and 19.8% respectively. The total fraction of alkenes and alkanes was higher in the biocrude obtained from alum-harvested biomass, compared to other biocrude samples. However, the transition of metal species from biomass to biocrude was very low in all the biocrudes. The authors would like to acknowledge the support of Qatar National Research Fund (QNRF, a member of Qatar Foundation) for providing the funding (under grant NPRP8-646-2-272 ) for this study. The authors appreciate the assistance of Dr. Ahmad, Mr. Attia, and Mr. Solaiman of Central Laboratory unit (QU) for the sample analyses using CHNS, EDX, and FTIR. The authors also appreciate the assistance of Ms. Noora from Environment Science Center (QU) for biocrude analysis using GC-MS. Appendix A Scopus

Microalgae can excrete exopolymer substances (EPS) with a potential to form hetero-aggregates with microplastic particles. In this work, two freshwater (Microcystis panniformis and Scenedesmus sp.) and two marine (Tetraselmis sp. and Gloeocapsa sp.) EPS producing microalgae were exposed to different microplastics. In this study, the influence of the microplastic particles type, size and density in the production of EPS and hetero-aggregates potential was studied. Most microalgae contaminated with microplastics displayed a cell abundance decrease (of up to 42%) in the cultures. The results showed that the formed aggregates were composed of microalgae and EPS (homo-aggregates) or a combination of microalgae, EPS and microplastics (hetero-aggregates). The hetero-aggregation was dependent on the size and yield production of EPS, which was species specific. Microcystis panniformis and Scenedesmus sp. exhibited small EPS, with a higher propension to disaggregate, and consequently lower capabilities to aggregate microplastics. Tetraselmis sp. displayed a higher ability to aggregate both low and high-density microplastics, being partially limited by the size of the microplastics. Gloeocapsa sp. had an outstanding EPS production and presented excellent microplastic aggregation capabilities (adhered onto the surface and also incorporated into the EPS). The results highlight the potential of microalgae to produce EPS and flocculate microplastics, contributing to their vertical transport and consequent deposition. Thus, this work shows the potential of microalgae as biocompatible solutions to water microplastics treatment. published

International audience; Integrated multi-trophic aquaculture (IMTA) systems are a promising solution for sustainable aquaculture combining nutrient recycling with increased biomass production. An innovative land-based recirculating aquaculture system (RAS) was studied in France for a 60-day experiment. It combined a European sea bass (Dicentrarchus labrax) RAS with two other production systems: high rate algal ponds (HRAP) with natural marine polyspecific algal assemblages, and oysters in separate open tanks. The objective was the assessment of: 1) the efficiency and the stability of the microalgae bioremediation of the effluent from a fish RAS in spring and summer, 2) the abundance and the diversity patterns of the microalgae biomass for consumption in the oyster compartment of the IMTA. Silicate was added every week after the beginning of the experiment for maintaining a Si:N:P molar ratio of 10:5:1 in the HRAP to encourage the growth of diatoms. The HRAP have an overall removal efficiency of 98.6 ± 0.2% for NO3-N, 98.0 ± 0.4% for NO2-N, 97.3 ± 0.7% for NH4-N and 96.1 ± 0.6% for PO4-P, with removal rates of 335.8 ± 0.8, 23.6 ± 0.2, 30.9 ± 0.2, and 22.3 ± 0.2 mgm−2 d−1, respectively. The concentration of total suspended solid (TSS) and chlorophyll a (chl a) increased during the experiment and reached maximum values on day 46 (135.3 ± 34.7 mg TSS l−1 and 0.42 ± 0.03 mg chl a l−1) after which the microalgae collapsed due to a CO2 limitation (pH ca. 10). Sequencing analysis revealed that the microalgae community was dominated by Tetraselmis sp. from day 1 to day 16 (45.7% to 73.8% relative abundance). From day 30 to day 43 the culture was dominated by diatoms, Phaeodactylum sp. (83.4% to 98.1% relative abundance). Although the stable carbon isotope signatures confirmed that the microalgae were consumed, oysters' growth was limited in the RAS-IMTA, suggesting that oysters were under stress or not fed enough

Motility is a fundamental property which includes a number of highly attuned cellular functions that enable an organism to move in a coordinated fashion. Many microorganisms use different external chemical and physical factors in order to direct their search toward food or a suitable niche for survival and growth. The aim of this study was to develop procedure for the cell motion analysis in order to determine the cell speed changes in laboratoryinduced stress conditions. Dunaliella tertiolecta and Rhodomonas maculata, two motile biflagellate algal species differing in cell symmetry and position of flagella, were selected as model organisms. Motility of algal cells was examined in dependence of changing concentrations of toxic heavy metal cadmium and different salinities in the growth media. Determination of cell motility, corresponding to length and shape of trajectories, were recorded with the open access bioimage software ICY (The Institut Pasteur, France). Differences in cell speed are related to morphological features of the corresponding algal species. Cell adaptation response to cadmium stress is manifested through decrease in cell speed, as well as changes in motion and pattern of movement. The obtained results give a deeper insight into the viability of algae population and will contribute in understanding of the adaptation response mechanism of cell to stress in aquatic ecosystems.

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

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

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

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

The inclusion of new ingredients in fish feed can affect the physical quality of the pellets. In order to study the effect of the addition of microalgae on the physical properties of the pellets, 15 extruded diets were studied that included three different species of microalgae (Nannochloropsis gaditana, Tetraselmis chuii and Chlorella vulgaris) at five different inclusion levels (0, 2.5, 5, 10 and 15%). The feed mixtures were extruded using a single-screw extruder (barrel temperature profile: 90–95–100 °C; die temperature: 105 °C; screw speed: 40–50 rpm). The physical properties studied included: expansion ratio, density, hardness, pellet durability index, water absorption index, water solubility index, floatability, sinking velocity, fat leakage and starch gelatinization. The present study showed that the physical properties of the pellets are influenced by the type and amount of microalgae used. The physical quality of the feed was modified, generally increasing its hardness and durability and reducing the fat leakage.

Bacteria are remarkably associated with the growth of green algae Tetraselmis which are used as a feed source in aquaculture, but Tetraselmis-associated bacterial community is characterized insufficiently. Here, as a first step towards characterization of the associated bacteria, we investigated the community composition of free-living (FLB) and particle-associated (PAB) bacteria in each growth phase (lag, exponential, stationary, and death) of Tetraselmis suecica P039 culture using pyrosequencing. The percentage of shared operational taxonomic units (OTUs) between FLB and PAB communities was substantially high (≥92.4%), but their bacterial community compositions were significantly (p = 0.05) different from each other. The PAB community was more variable than the FLB community depending on the growth phase of T. suecica. In the PAB community, the proportions of Marinobacter and Flavobacteriaceae were considerably varied in accordance with the cell number of T. suecica, but there was no clear variation in the FLB community composition. This suggests that the PAB community may have a stronger association with the algal growth than the FLB community. Interestingly, irrespective of the growth phase, Roseobacter clade and genus Muricauda were predominant in both FLB and PAB communities, indicating that bacterial communities in T. suecica culture may positively affect the algae growth and that they are potentially capable of enhancing the T. suecica growth.

Plankton is the primary food sources for many fish larvae as well as other organisms during their early stage of development. Zooplankton such as copepods play a major role in freshwater and marine environment as live food that offer great variety of sizes, species and nutritional value to the larvae. The aim of this study is to increase the nutritional value of copepod and its effect on Penaeus monodon post-larvae growth performance. The experiment was carried out 30 days and comprised with four different treatments of diets. The diets fed to copepod consisted of algal diet which is Tetraselmis sp. that acted as a control followed by three types of vegetable-based diet which is carrot, water spinach, and lettuce. The efficiency of the copepods enriched was further evaluate on its growth, survival and proximate composition. The outcome of the study showed that highest specific growth rate (SGR) in P.monodon post-larvae was obtained when fed with copepods enriched water spinach (11.28±0.38%) and the highest survival rate of P.monodon was obtained when being fed with copepods enriched Tetraselmis sp. (91.67±0.29%). Proximate analysis composition for enriched copepods and P.monodon fed with enriched copepods showed the water spinach produce highest protein and lipid content compared to other enrichment. The current result showed that vegetable based are able to replace the microalgae, hence it also can gave an advantages to the economy in aquaculture and higher yields.

Veliger larvae of giant clams are demonstrable planktotrophs and provision of a particulate food source is generally accepted to improve hatchery production. However, the appropriateness of continuing to administer particulate food after larvae settle and develop as pediveligers is unclear. This study evaluated whether larval (age and size) and microalgal (species and cell density) factors influenced the capacity for pediveligers of Tridacna noae to ingest and digest cells from commercially available microalgae concentrates. Pediveligers at 6 and 10-days post-fertilisation were offered one of four microalgae species (Isochrysis sp., Pavlova sp., Tetraselmis sp., Thalassiosira weissflogii) at two cell densities (4000 and 8000 cells mL−1) and subsequently examined using epifluorescence microscopy. The appropriateness of continuing to administer microalgae as a food source was found to diminish as pediveligers approached metamorphosis, with negligible ingestion occurring at 10-days post-fertilisation. Earlier in development, at 6-days post-fertilisation, ingestion was significantly influenced by larval size, microalgae species, and microalgae cell density. Considering capacity for both ingestion and digestion, the Isochrysis sp. and Tetraselmis sp. microalgae concentrates had the greatest potential as a particulate food source for pediveligers of T. noae. The results of this study provide a basis for further refinement of giant clam hatchery procedures utilising microalgae concentrates as a larval food source.

This paper reports the results of a complete kinetic study, based on thermogravimetric characterisation, to compare the performance of Nannochloropsis sp. and Tetraselmis sp. microalgae during pyrolysis and combustion with air, enriched air and oxygen. The analysis has been carried out including both the single- and multi-step approach studying the effect of different model-free methods and heating rates. In addition, the study brings together the pseudo-components (obtained by peaks deconvolution) model and master plot methodology to discriminate the kinetic model followed by the different processes with the aim to determine the kinetic triplet (activation energy, reaction order and pre-exponential factor). It results that the thermal decomposition of the microalgae cannot be represented by a single reaction mechanism for the whole conversion range, but several parallel decomposition reactions have been taken into account, and the kinetics have been assessed from each decomposition kinetic of the pseudo-components. The kinetic profiles can be interpreted as the combined effects of reaction-order (F), nucleation (A), exponential nucleation (P) and geometrical contraction (R) mechanisms.