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Penaeus monodon larvae were reared from zoea 1 (Z 1 ) to mysis 3 (M 3 ) using two different algal feeds, Chaetoceros calcitrans and Tetraselmis chuii. Artemia nauplii were added to both treatments at mysis 2 . Mean survival and growth rates in both treatments were different at 5% level of significance on the second and third day of culture, but did not differ during the mysis stage and the end of the 8-day culture period. Z 3 and M 3 larvae fed with C. calcitrans had a lower crude protein but a higher lipid content than T. chuii -fed larvae. Differences in carbohydrate content were noticed in M 3 larvae. The implication of the findings are discussed.

Biomethanation of algae is an elegant way to convert solar energy into a chemical fuel, i.e. methane. The microbiological process of methanogenesis is leading to a reliable technology. Favorable running conditions were elicited by experiments at the laboratory scale. The process is being developed at the 1-m/sup 3/ scale at Lamezia (Italy). From these experiments, conceptual parameters for a full-scale demonstration plant are calculated.

Carteria wettsteinii Schiller (1913) has been isolated from Golfo di Napoli and investigated by means of electron microscopy which revealed micro-anatomical features characteristic of the genus Tetraselmis. The species is commonly present in Golfo di Napoli during summer with cell numbers 102–106 cells-litre−1, occasionally producing blooms of 107 cells·litre−1.

Effects of temperature, algal food, feeding rate and larval density on the development and shell growth stage of conch veligers, Strombus costatus , were studied over a period of 30 days in laboratory cultures. Experiments were conducted at 24°C, 28°C, 32°C and 28 ± 2°C. After hatching, the veligers developed to metamorphosis within 26 days at 28°C, 28 days at 28 ± 2°C and 35 days at 24°C. Rearing was not successful at 32°C. Conch larvae were fed with the algae Isochrysis aff. galbana (Tahiti), Tetraselmis chuii and Isochrysis/Tetraselmis mix. The best rate of growth per day was 39.69 μm in Isochrysis/Tetraselmis mixed food. Experiments were conducted at 500, 1000, 2000, 3000, 4000, 5000 and 6000 Isochrysis aff. galbana cells larva −1 day −1 . The veligers showed an optimal growth at 3000 cells larva −1 day −1 . The conch veligers were reared at five larval densities: 100, 200, 300, 400, and 500 larvae/l, and showed an optimal growth at 100 larvae/l, while poorest growth was observed at 500 larvae/l.

The effect of different algal diets on the growth of copepod Acartia tonsa was investigated under laboratory conditions. Copepod were fed for fifteen days with seven algal diets which included three mono-algal diets such as Isochrysis sp. (T1), Chaetoceros sp. (T2) and Tetraselmis sp. (T3), and four mixed algal diets such as Tetraselmis sp. and Isochrysis sp. (T4); Tetraselmis sp. and Chaetoceros sp. (T5); Isochrysis sp. and Chaetoceros sp. (T6) and Tetraselmis sp., Isochrysis sp. and Chaetoceros sp. (T7) in water of temperature 25±1oC and salinity of 20 ‰ with treatments in triplicates. Copepod fed mono-species algal diet Isochrysis sp. produced the highest mean body length at the early stage of culture. Growth was highest in copepod fed mixed algal diet of T7, while the least growth was observed in copepod fed mixed algal diet of T6. However, growth in copepod fed mixed algal diets of T7 and T4 were not significantly different (P>0.05). The study showed the viability of the local alga Isochrysis as food item both as mono-algal diet and in mixed algal diets for optimal growth of copepod Acartia tonsa. This makes the culture of the copepod a promising live feed in aquaculture practices in Nigeria.Keywords: Tetraselmis sp., Isochrysis sp., Chaetoceros sp., f/2 medium and Conwy medium

The photosynthetic fixation of14CO2was studied in 10 species of chlorophycean algae and in 9 isolates of prasinophycean algae of the genus Tetraselmis.Green seaweeds had photosynthetic rates of 2.2 to 4.4 mg CO2 × h−1 × g−1, accumulated starch, glucose, fructose, and sucrose, and excreted very little recent photosynthate.Dunaliella spp. were distinguished by a high level of organic excretion (to 29.2% of the14C fixed in 2 hours), the production of glycerol and hydrogen sulfide, and the absence of dimethyl-β-propiothetin.Tetraselmis spp. excreted relatively small amounts of photosynthate in 2 hours, and produced mannitol and dimethyl-β-propiothetin but not hydrogen sulfide.

Characteristics of the growth of PhaeodactyZum in culture in fertilized sea water in 1,000-L concrete tanks are dcscrihed. Successful experiments showed a constant pattern of events as follows: 1) active growth of PhaeocZnctyZum, 2) reduction in growth rate of Phaeodnctylum, 3 ) period of constant cell density, or rapid decline, 4 ) rcgcneration period, and, 5) second period of active growth, Growth of Phaeodactylum shows seasonal variation, but final population density reached is more or less constant. N and P utilization follow parallel courses, the mean ratio of N:P uptake during the 1st growth period bdng 6.5 2 0.44: I. During growth, inorganic P is incorporated in the cells as particulate organic P. Following dcclinc of PhaeocZactyZum dissolved organic P incrcascs, and later, inorganic P is regencratcd and may be reutilized during the 2nd growth phase. Decline of Phneodactylum is normally associated with increase of the heterotroph Mows. Thcrc was a close relationship bctwecn peak numbers of Mows and the number of Phaeotlactylum in the previous peak. The second growth phase consisted either of one or more chlorophycean flagcllatcs, or of Phaeoductylum. Estimates of production based on 02 bottle exposures, change in inorganic P, change in pH, and change in packed ccl1 volume agree closely, although initial uptake of P may bc excessive. Estimates from change in inorganic P indicate a seasonal variation in the rate of organic production of up to 2.2 gC/m”/24 hr in March, 4.9 gC/m2/24 hr in May-August, and 2.0 gC/m”/24 hr in October, November. For Tetruselmis production rates up to 5.2 gC/m2/24 hr were recorded. The efficiency of utilization of solar energy for Phaeoductykm culture ranged from 3.0 to 4.4% with a mean for 5 cstimatcs of 3.7%. For Tetraselmis values of 1.0-1.3s wcrc obtained.

Polysaccharides isolated from the unicellular organisms. Haematococcus pluvialis and Tetraselmis carteriiformis have been examined by chemical and enzymic methods, and characterised as having starch-type structures. After dispersion in alkali, the H. pluvialis starch was fractionated into amylose and amylopectin components. Fractionation of the T. carteriiformis starch was not completely successful, although an amylopectin component was obtained. The starches and components from both organisms were very similar in composition and structure to those from higher plants.

Thirty-one species of marine unicellular algae in pure culture were tested for survival in darkness at 20 C in seawater buffered at pH 7.6–7.8 and enriched with nitrate, orthophosphate, silicate, vitamins (B12, thiamin, biotin), and trace-metal ions (chelated with ethylenediamine tetraacetate). None of the species showed any significant growth in darkness but six species [including two cyanophytes, two chlorophytes (Nannochloris oculata, Tetraselmis maculata), one rhodophyte (Porphyridium cruentum), and one diatom (Phaeodactylum tricornutum)] resumed growth in light after 24 weeks in darkness (the maximum period tested). Another chlorophyte survived 18 weeks, two chrysomonads and one cryptomonad 12–14 weeks, and most other algae (including ten diatoms) 6–8 weeks of darkness. Skeletonema costatum, Hemiselmis virescens, Coccolithus huxleyi, and Amphidinium carteri showed the lowest survival potential ranging from one to three weeks. The observed darkness-survival may have ecological relevance to th...

Fructose diphosphate aldolase activity was examined in acetone powders and cell-free extracts of 15 photoautotrophically grown marine planktonic species belonging to 6 algal divisions as follows: Chlorophyta: Tetraselmis maculata, Dunaliella tertiolecta; Chrysophyta: Monochrysis lutheri, Isochrysis galbana, Prymnesium parvum, Coccolithus huxleyi; Bacillariophyta: Phaeodactylum tricornutum, Skeletonema costatum, Cyclotella nana; Cryptophyta: Cryptomonas sp., Rhodomonas lens, Hemiselmis virescens; Pyrrophyta: Amphidinium carteri; Cyanophyta: Anacystis marina, Agmenellum quadruplicatum. Indications of the types of aldolase (Rutter's classes) present in each alga were obtained from comparative studies of the effects of pH and of the following reagents on the activity: ethylenediamine tetraacetate, dithiothreitol, p-chloromercuriphenyl sulfonate. Type I (higher plant-animal type) aldolase only was indicated in the 2 chlorophytes, in I chrys-ophyte (M. lutheri), and in 1 bacillariophyte (P. tricornutum), while the remaining algae appeared to contain either exclusively or principally Type II (bacterial-fungal type) aldolase. The evolutionary implications of these findings are discussed.

The 80% alcohol-soluble carbohydrates accumulated by 23 species of green marine phytoplankton were examined after [Formula: see text] of photosynthesis in NaH14CO3. The presence of dimethyl-β-propiothetin (DMPT) and H2S was also noted.The major radioactive products in the Chlorophyceae were sucrose (five isolates), glycerol (three isolates), and mannitol (two isolates). Mannitol and sucrose were never found in the same extract, although glycerol and sucrose were found together in two organisms. DMPT occurred in Chlorococcum sp., and H2S appeared only in one Chlamydomonas sp.All 13 organisms assigned to the Prasinophyceae produced 14C-mannitol, and all except Pyramimonas sp. contained DMPT. H2S was observed in one strain of Tetraselmis sp. Sucrose and glycerol were not found in this class.

In the first experiment the effects of rotifer enrichment and feeding frequency on larval performance of red porgy Pagrus pagrus were studied. Larvae (2 days post-hatching = 2 dph) were fed s-type rotifers (∼20 rotifers/mL) enriched with one of the four different treatment media: Rotifer Diet (microalgae Nannochloropsis oculata and Tetraselmis chuii), DHA Protein Selco, Algamac 3000 (Schizochytrium sp.) and Algamac + ARA (arachidonic acid). Larvae were fed daily at full ration or twice daily at half ration. Larval growth and survival (mean = 22.8%) were satisfactory through 16 dph under all treatments; however, resistance to hyposaline challenge (Survival Activity Index = SAI) was positively correlated (P

The larvae of the Pacific white shrimp Litopenaeus vannamei are fed, from the stage of protozoea I until to protozoea III (PZ III), with microalgae. The survival rate, duration of the terms of ZI-ZIII and total length of protozoea larvae (PZ) of L. vannamei were survived. The shrimp larvae fed with the six treatments of microalgae (Chaetoceros muelleri, Isochrysis galbana, Tetraselmis tetrathele, C. muelleri : I. galbana, C. muelleri: T. tetrathele and I. galbana: T. tetratheie). The biochemical composition (protein, carbohydrate, lipid and energy) of the algae and the larvae fed those algae were also measured. The largest sizes were recorded for larvae fed with the mixture C. muelleri and I. galbana (4.35 mm) and smaller sizes were observed on larvae fed with I. galbana (3.04 mm) (P\0.05). The larvae fed with mixture T. tetrathele and C. muelleri (88.42 %) and I. galbana and T. tetrathele (84.50 %) had the highest survival in experimental treatments. The lowest time for development was observed in larvae fed with mixture of T. tetrathele and C. muelleri (92.6 h). The larvae fed with mixture I. galbana and T. tetrathele had the highest protein and carbohydrate levels as compared with other treatments. Also highest lipid level and gross energy were shown in larvae fed with mixture C. muelleri and I. galbana (P\0.05). The results showed that L. vannamei larvae fed with C. muelleri and the mixed diets containing this species (C. muelleri ? Isochrysis sp., C. mueller- i ? Tetraselmis sp.) had the highest growth and survival among treatments.

Plasma membranes isolated from the marine unicellular alga Tetraselmis (Platymonas) viridis were phosphorylated by [γ-32P]ATP, and membrane proteins were then analyzed by PAGE in SDS, under acidic conditions. Three radioactive components with apparent molecular masses of 100 kDa, 76 kDa, and 26 kDa were detected. The phosphorylation of one of them, the 100 kDa polypeptide, was specifically stimulated by Na+. Vanadate almost completely inhibited the Na+-mediated phosphorylation of the peptide. The phosphate bound to this peptide underwent rapid turnover and was discharged by hydroxylamine. The 100 kDa phosphopeptide was sensitive to ADP. The conclusion is drawn that the 100 kDa phosphopeptide is a phosphorylated intermediate of the Na+-transporting ATPase in the T. viridis plasma membrane.

Sodium accumulation by the Na+-ATPase in the plasma membrane (PM) vesicles isolated from the marine alga Tetraselmis (Platymonas) viridis was shown to be accompanied by deltapsi generation across the vesicle membrane (positive inside) and H+ efflux from the vesicle lumen. Na+ accumulation was assayed with 22Na+; deltapsi generation was detected by recording absorption changes of oxonol VI; H+ efflux was monitored as an increase in fluorescence intensity of the pH indicator pyranine loaded into the vesicles. Both ATP-dependent Na+ uptake and H+ ejection were increased by the H+ ionophore carbonyl cyanide m-chlorophenylhydrazone (CICCP) while deltapsi was collapsed. The lipophilic anion tetraphenylboron ion (TPB-) inhibited H+ ejection from the vesicles and abolished deltapsi. Based on the effects of CICCP and TPB- on H+ ejection and deltapsi generation, the conclusion was drawn that H+ countertransport observed during Na+-ATPase operation is a secondary event energized by the electric potential which is generated in the course of Na+ translocation across the vesicle membrane. Increasing Na+ concentrations stimulated H+ efflux and caused the decrease in the deltapsi observed, thus indicating that Na+ is likely a factor controlling H+ permeability of the vesicle membrane.

This study evaluates the in vitro protein hydrolysis of four microalgae (Tisochrysis lutea, Nannochloropsis gaditana, Tetraselmis suecica and Scenedesmus almeriensis) by intestinal proteases of gilthead sea bream (Sparus aurata) and Senegalese sole (Solea senegalensis). The hydrolysis of protein was monitored at different sampling times by electrophoretic techniques, and the quantification of the free amino acids released by proteases. Overall, S. aurata or S. senegalensis proteases hydrolysed microalgae protein in a similar way. The highest hydrolysis values (coefficient of protein degradation, CPD > 70%) were obtained for Tisochrysis and Nannochloropsis biomasses, which showed a progressive and almost complete proteolysis at the end of the in vitro assay. Tetraselmis and Scenedesmus protein was also hydrolysed, but SDS-PAGE revealed that two protein fractions remained virtually intact at the end of the in vitro assay. The final amount of free amino acids released in vitro by the fish digestive enzymes ranged from 9 to 25 g 100 g protein−1. A linear relationship between CPD and the amount of free amino acids released was found, a fact that suggests that microalgae protein is hydrolysed efficiently by the digestive proteases of both fish species. The present study provides information about the protein availability from selected microalgae, which will aid in the initial evaluation of the microalgae as potential protein sources in feeds of two important farmed fish species.

KEYWORDSMarine microalgae;Dicentrarchus labrax postlarvae;Growth;Antimicrobial;GC–MSAbstract This study investigates the microbial profile and antimicrobial activity of four marinemicroalgae species, Tetraselmis chuii, Nannochloropsis salina, Isochrysis galbana and Chlorella salinaused in aquaculture of Dicentrarchus labrax in the post larval stage to estimate which was the bestalgal species that could be used as a green water technique and achieving the maximum rate ofgrowth and survival of D. labrax post larvae. The results represented a significant increase in thelength and width of D. labrax at p < 0.05 recorded in the case of enrichment with I. galbanafollowed by N. salina, and the most weight was recorded in the case of N. salina as compared withthe control. Significant increase in percentage of survival of D. labrax was recorded in the case ofC. salina and T. chuii (70% and 60.1%, respectively) as compared with the control (22%). Theantibacterial activity (AU) of the different microalgal ethanolic extracts against fish indicatorpathogens was determined. The results indicated that the ethanolic extracts of C. salina and T. chuiihave the most positive records against the fish indicator pathogens (Escherichia coli, Pseudomonasaeruginosa, Vibrio damsela, Vibrio fluvialis and Aeromonas hydrophila). The current studywas extended to determine the GC–MS of ethanolic extract of C. salina and T. chuii. The main con-stituents detected in the ethanolic extract were organic acids like hexadecanoic acid, octadecanoicacid, and an acyclic diterpene alcohol like phytol.a 2014 Hosting by Elsevier B.V. on behalf of National Institute of Oceanography and Fisheries.

Forty-five axenically grown algal (sensu lato) species representing six divisions—that is. 13 Chlorophyceae, 14 Chrysophycophyta, five Dinophycophyta, seven Cryptophycophyta, two Rhodophycophyta, and four Cyanochloronta—were aseplicaily presented separately as potential food sources to the marine helerotrich ciliate Fabrea salina under standardized algal number, medium, lighting, and temperature. The algae can be placed into three groups based on their effect on the intrinsic growth rate of the ciliate. Nutritious: Rhodomonas lens, cryptomonad LIS1, Dunaliella parva, Prasinodadus marinus, Chroomonas salina, D. tertiolecta, Chaeloceros galvestonensis, D. primolecta, Phaeodactylum tricornutum, D. salina, Isochrysis galbana, Cylindrothecaclosterium, cryptomonad strains M2, WH2 & FSA, Chroomonas sp., P. lubricus, and Peridinium trochoideum. Maintamers: Cyanobacterium strain Tigriopus blue green, P. triquetum. Monochrysis lutheri, Exuviella gracilis, Platymonas tetrathele. Cyclotella caspa, Crypthecodinium cohnii, Prasinocladus C5 strain, D. viridis, Nannochloris occulata, Tetraselmis gracilis, Anacystis marinum, Rhodosorus marinum, and Thalassiosira pseudonana. Nonnutritious: Stichococcus immobilis, Hymenomonas sp. strain 150, Syracosphaera sp. strain 181, Tetraselmis verrucosa, Thalassiosira fluviatilis, Microcoleus chthonoplastes, Synechococcus sp., Pavlova gyrans, Prymnesium parvum, Coccolithus huxleyi, Olisthodiscus luteus, Amphidinium carterii, and Porphyridium aerugineum. There was no apparent relationship between a given taxon and the nutritional value of the group, with the possible exception of the Cryptophycophyta.

Nickel is required for urease synthesis by Phaeodactylum tricornutum and Tetraselmis subcordiformis and for growth on urea by Phaeodactylum. There is no requirement for nickel for urea amidolyase synthesis by Chlorella fusca var. vacuolata. Neither copper nor palladium can substitute for nickel but cobalt partially restored urease activity in Phaeodactylum. The addition of nickel to nickel-deficient cultures of Phaeodactylum or Tetraselmis resulted in a rapid increase of urease activity to 7-30 times the normal level; this increase was not inhibited by cycloheximide. It is concluded that nickel-deficient cells over-produce a non-functional urease protein and that either nickel or the functional urease enzyme participates in the regulation of the production of urease protein.

Nannochloropsis oculata was cultured in the Japanese summer season and tested for larval growth of the swimming crabPortnus tritberculatus. Three treatments (1, 2 and 3) were prepared : treatment 1 ; feeding of Artemia nauplius and the rotifer cultured with N. oculata, treatment 2 ; feeding of Artemia nauplius and the rotifer cultured with T. tetrathele, and treatment 3 ; with neither Artemia nor rotifer. The number of crab larvae over 11 days till megalops stage decreased gradually from 35 to 0 - 7 in treatment 1, and 1 - 4 in treatment 2. In tratment 3, the number of survival in the larvae decreased rapidly to zero in few days. The low content of n-3 highly unsaturated fatty acids (HUFA) in N. oculata might have caused the low survival.

The green algal flagellate, Tetrasehnis, is a key transition organism in the phylogeny of green algae. It has been proposed that the cell wall of Tetraselmis arose evolutionarily from the fusion of scales and that this event secondarily caused the alteration of some cytoplasmic processes such as mitotic and cytokinetic mechanisms. Ultrastructural and developmental studies of the cell wall were performed with several strains of Tetraselmis. Two major wall types are reported. The wall of type 1 cells consists of a thick inner region covered by a layer of regularly repeating subunits of 26 nm, comparable to the subunits found in the median W2-W6 layer of Chlamy-domonas. The more elaborate type 2 cell wall consists of a thick median wall layer, homologous to the type 1 inner wall, with additional inner and outer strata of hairs, grains and scales. Development of the cell wall begins in the endomembrane system, particularly the Golgi apparatus, where fibrillar tufts and electron-dense droplets are synthesized, modified and transported to the outside. Here, the tufts and droplets are displaced around the protoplast and assemble in several steps to yield the intact wall. Edge-growth assembly of the wall occurs here synchronously with cytoplasmic developments to yield the characteristic anterior flagellar pit. Models explaining various aspects of this development are discussed. When released from the cell, the wall subunits are not completely comparable to stellate scales, but appear to correspond to developmental stages of scales in green flagellates possessing body scales.

Convoluta roscoffensis is an intertidal acoel turbellarian (fflatworm1) that is locally abundant on sandy beaches of the Brittany coast of France and nearby Channel Islands. It is a conspicuous member of the beach fauna, for two reasons: first, the animals are green, due to the presence of algal symbionts of the genus Tetraselmis (=Platymonas, Prasinocladus) in their tissues (Parke & Manton, 19 67); and, secondly, they are gregarious, forming large dark-green patches on the surface of the beach at low tide (Holligan & Gooday, 1975). The details of the life cycle of C. roscoffensis was established by Keeble & Gamble (1907). The adult animals reproduce exclusively sexually and the fertilized eggs are deposited, within a common gelatinous capsule, in the sand. The algal symbionts are not transmitted directly into the eggs and the association is reestablished at each generation of C. roscoffensis when recently-hatched juveniles feed on free-living algae in the interstitial water. The symbiosis appears to be obligate for C. roscoffensis; all adult animals are green in the field and, in the laboratory, aposymbiotic juveniles die within a few weeks of hatching.

It is now fairly well recognized that the symbioses between microalgae and invertebrates demonstrate specificity (Trench, 1979, 1987). The realization that specificity existed in such associations was not forthcoming until the specific identities of the interacting organisms were resolved, and this depended to a large extent on the isolation, culture and taxonomic analysis of the algae involved. After isolation and culture of the ‘zoochlorellae’ from the flatworm Convoluta roscoffensis, Parke and Manton (1967) identified the algae as the prasinophyte Tetraselmis (Platymonas) convolutae (Hori et al 1982), and the ‘zooxanthellae’ symbiotic with Convoluta convoluta were identified as the diatom Licmophora sp. by Apelt (1969) after they were isolated and brought into culture. Based on the isolation and culture of symbiotic dinomastigotes, D.L. Taylor (1971, 1974) could distinguish between the amphidinioid and gymnodinioid symbionts.

This paper reports the results of the research on the mass culture of phytoplanton organisms in fertilized seawater carried out in the south of Italy (Lamezia Terme — Calabria) during 1980 and the first five months of 1981. The main goals of this work have been the evaluation of the productivity of marine photosynthetic organisms using Tetraselmis sp. as a model organism, the development of the appropriate culture technique and the selection of al gal strains with growth properties suitable for the MCL process. Preliminary results on the mass culture of two “filterable” strains are reported.

11 páginas, 4 figuras, 2 tablas, Experiments were conducted in order to observe the effect of five diets on the population development of the rotiferBrachionus plicatilis Müller under laboratory conditions. Diets were based on baker’s yeast (Saccharomyces cerevisiae) and the algaeTetraselmis suecica andIsochrysis galbana, mixed, or as simple diets. Growth rates, fecundity and biometric parameters were studied for 15 days. The cultures were divided in a logarithmic phase and a harvesting phase. Rotifers fed onTetraselmis, alone or mixed with yeast orIsochrysis, gave good performances with the best results in all the parameters studied. Average growth rates in all diets were similar during the exponential phase, with values ranging from 0.72 (Tetraselmis andTetraselmis + yeast) to 0.47 (yeast). During the harvesting phase there were high differences between diets, with rates highly reduced in the yeast-group (0.17) and good rates whenTetraselmis was ingested (0.65–0.51). This alga had a positive influence on the rotifers, increasing individual growth and fecundity., This work was supported by a grant from the CAICYT.

The research aims (1) at improving yields and rates of biomethanation of algae and (2) at correlating composition of algal batches with methane productivities. Previously, it had been shown with Hydrodictyon algae that a two step system (liquefaction and biomethanation) gave improved results over a one step, completely-mixed system. In the present work, the influence of environmental factors such as temperature and load on the first step were investigated. Although the results of the liquefaction varied somewhat with the running conditions, these variations were without appreciable effect on the overall methane productivities. Besides, preliminary results of a two step system, a first percolating step followed by an upflow methane digester with active biomass accumulation look promising. Application of the two step biomethanation process to the algae Tetraselmis elicited a problem of reliability with time, presumably due to enhanced concentrations in ammonia resulting from increased biodegradation of proteins. Increasing the salt (NaCl) content (presently up to 20 g × l-1) in the mixed liquor of a one step digester had no influence on the process. Biomethanation of six algal species showed good although inequal potential for methane production with yields from 0.20 to 0.33 1 CH4 × g-1 VSo. Monitoring based on volatile solids (VS) contents appears erratic in the two step process because samples contain variable amounts of compounds volatile below 100 °C. Monitoring based on COD appears more reliable. Lagoons for the production of ton amounts of freshwater Hydrodictyon algae in industrial luke-warm were constructed. Production and population analyses of the algae are in progress.

The yields, photosynthetic efficiencies, and proximate composition of several microalgae were compared in dense cultures grown at light intensities up to 70% sunlight. Yields ranged from 3.4 to 21.7 g dry weight/m/sup 2/ day. The highest yield was obtained with Phaeodactylum; the lowest in Botryococcus cultures. The same species had the highest and lowest efficiencies of utilization of photosynthetically active radiation. In nitrogen-sufficient cells of all but one species, most of the dry weight consisted of protein. Lipid content of all species was 20 to 29%, and carbohydrate content 11 to 23%. Lipid content increased somewhat in N-deficient Phaeodactylum and Isochrysis cells, but decreased in deficient Monallanthus cells. Because the overall dry weight yield was reduced by deficiency, lipid yields did not increase. However, since the carbohydrate content increased to about 65% in N-deficient Dunaliella and Tetraselmis cells, the carbohydrate yield increased. In Phaeodactylum the optimum light intensity was about 40% of full sunlight. Most experimets with this alga included a CUSO/sub 4/ filter to decrease infrared irradiance. When this filter was removed, the yield increased because more red light in the photosynthetically active spectral range was included. These results should prove useful to workers attempting to maximize yields andmore » efficiencies, but additional studies are needed. 69 references, 27 figures, 18 tables.« less

Any complex substrate biomass can be characterised by its “fermentation profile”, i.e. a complex substrate biomass, in the presence of an ubiquitous microbial mixed culture and under given environmental conditions,ferments readily in mainly only one unique way. This micro-ecological model axiom is substantiated by the study of non-sterile fermentations of two complex substrate biomasses, the algae Hydrodictyon and Tetraselmis, as a function of various environmental conditions.

A detailed study of the life history of the rotifer Brachionus plicatilis was done at 20 °C, 20 ppt salinity, and 90 mg C 1−1 food concentration. Rotifers were grown individually in culture plate wells (150 µl culture volume) and fed Isochrysis galbana Tahiti, Tetraselmis sp., Nannochloris atomus, or a l : 1 mixture (weight) of two of the algae. Observations were made every 2–8 hr and rotifers were sized and transferred to new food daily. A total of 19 different parameters were compared. Rotifers fed Isochrysis averaged 21 offspring per female, a 6.7 day reproductive period, a lifespan of 10.5 days and a mean length of 234 µm. After Isochrysis, the foods giving the highest growth, survival, and reproduction in decreasing order were Isochrysis + Nannochloris, Nannochloris, Isochrysis + Tetraselmis, Tetraselmis + Nannochloris, and Tetraselmis. Although the small volume culture system used in this study seems appropriate for studying life history of B. plicatilis, the results cannot always be directly applied to larger cultures.

This study investigated the feasibility of microalgal biomass production using waste nitrogen fertilizers (WNFs) generated by the Qatar Fertiliser Company (QAFCO). From the plant, three types of WNFs (WNF1, WNF2, and WNF3) were collected; WNF1 and WNF2 had high solubility (e.g., 1000 g/L) whereas WNF3 had low solubility (65 g/L). For a lower dosage (i.e., 100 mg N/L) of these WNFs, >98% of nitrogen was soluble in water for WNF1 and WNF2; however, 52 mg N/L was soluble for WNF3. Nitrogen content in these wastes was 44, 43, and 39% for WNF1, WNF2, and WNF3, respectively. As these WNFs were used as the sole nitrogen source to grow Tetraselmis sp., Picochlorum sp., and Synechococcus sp., Tetraselmis sp. could utilize all the three WNFs more efficiently than other two strains. The biomass yield of Tetraselmis sp. in a 100,000 L raceway pond was 0.58 g/L and 0.67 g/L for mixed WNFs (all WNF in equal ratio) and urea, respectively. The metabolite profiles of Tetraselmis sp. biomass grown using mixed WNFs were very similar to the biomass obtained from urea-added culture – suggesting that WNFs produced Tetraselmis sp. biomass could be used as animal feed ingredients. Life cycle impact assessment (LCIA) was conducted for six potential scenarios, using the data from the outdoor cultivation. The production of Tetraselmis sp. biomass in QAFCO premises using its WNFs, flue gas, and waste heat could not only eliminate the consequences of landfilling WNFs but also would improve the energy, cost, and environmental burdens of microalgal biomass production.

We investigated the influence of high light stress on iodocarbon release by three species of marine phytoplankton from different algal classes: the prymnesiophyte Emiliania huxleyi, the prasinophyte Tetraselmis sp., and the diatom Thalassiosira pseudonana. Despite a pronounced decrease in the fluorescence-based maximum quantum yield for photosystem II (F v /F m ), increased iodocarbon release relative to lower light controls was not observed in any of the experiments performed. These findings do not support the hypothesis that upper-ocean iodocarbon concentrations are influenced by light-induced algal stress.

Cell surface carbohydrates play important roles in cell recognition mechanisms. Recently, we provided ev- idence that particle selection by suspension-feeding bi- valves can be mediated by interactions between carbohy- drates associated with the particle surface and lectins present in mucus covering bivalve feeding organs. In this study, we used lectins tagged with fluorescein isothiocya- nate (FITC) to characterize carbohydrate moieties on the surface of microalgal species and evaluate the effect of oyster mucus on lectin binding. These analyses revealed that concanavalin A (Con A), one of six lectins tested, bound to Isochrysis sp., while Nitzschia closterium reacted with Pi- sum sativum agglutinin (PNA) and peanut agglutinin (PEA). The cell surface of Rhodomonas salina bound with PNA and Con A, and Tetraselmis maculata cell surface was characterized by binding with PNA, PEA, and Con A. Pre-incubation of microalgae with oyster pallial mucus sig- nificantly decreased the binding of FITC-labeled lectins, revealing that lectins present in mucus competitively blocked binding sites. This decrease was reversed by wash- ing mucus-coated microalgae with specific carbohydrates. These results were used to design a feeding experiment to evaluate the effect of lectins on sorting of microalgae by oysters. Crassostrea virginica fed with an equal ratio of Con A-labeled Isochrysis sp. and unlabeled Isochrysis sp. pro- duced pseudofeces that were significantly enriched in Con A-labeled Isochrysis sp. and depleted in unlabeled microal- gae. Selection occurred even though two physical-chemical surface characteristics of the cells in each treatment did not differ significantly. This work confirms the involvement of carbohydrate-lectin interaction in the particle sorting mech- anism in oysters, and provides insights into the carbohy- drate specificity of lectins implicated in the selection of microalgal species.

Methanol and hexane extracts from Tetraselmis chuii, Nannochloropsis oculata, Chlorella minutissima and Rhodomonas salina were evaluated for total phenolic contents, radical scavenging activity (RSA), metal chelating potential against copper and iron ions and acetylcholinesterase (AChE) inhibition. Only the methanol extracts contained phenolic compounds. The hexane extracts had the highest RSA. The extracts had a higher capacity to chelate Fe2+ ions, more pronounced in the lowest concentration of the hexane extracts with values ranging from 73.3 ± 3.3% (R. salina) to 97.5 ± 1.1% (N. oculata). The highest AChE inhibitory activity was found in the hexane extracts at 10 mg/ml of C. minutissima (79.3 ± 1.9%), T. chuii (85.7 ± 0.7%) and R. salina (81.5 ± 7.5%). GC–MS analysis indicated polyunsaturated fatty acids and steroids as the most abundant compounds in the hexane extracts. The species under study provide a valuable source of antioxidants, metal chelators and AChE inhibitors.

Potassium ion (K+) channels have been observed in diverse viruses that infect eukaryotic marine and freshwater algae. However, experimental evidence for functional K+ channels among these alga-infecting viruses has thus far been restricted to members of the family Phycodnaviridae, which are large, double-stranded DNA viruses within the phylum Nucleocytoviricota. Recent sequencing projects revealed that alga-infecting members of Mimiviridae, another family within this phylum, may also contain genes encoding K+ channels. Here we examine the structural features and the functional properties of putative K+ channels from four cultivated members of Mimiviridae. While all four proteins contain variations of the conserved selectivity filter sequence of K+ channels, structural prediction algorithms suggest that only two of them have the required number and position of two transmembrane domains that are present in all K+ channels. After in vitro translation and reconstitution of the four proteins in planar lipid bilayers, we confirmed that one of them, a 79 amino acid protein from the virus Tetraselmis virus 1 (TetV-1), forms a functional ion channel with a distinct selectivity for K+ over Na+ and a sensitivity to Ba2+. Thus, virus-encoded K+ channels are not limited to Phycodnaviridae but also occur in the members of Mimiviridae. The large sequence diversity among the viral K+ channels implies multiple events of lateral gene transfer.

It was evaluated the effect of operational conditions in the production of Chlorella sp. after its selection from genus Chlorella sp., Scenedesmus sp., Nannochloris sp., Tetraselmis sp. and Dunaliella salina. Microalgae were inoculated in drinking water with addition of NPK fertilizer (N 24%, P 24%, K 18%), at a concentration of 0.5 g/L, agitation of 150 rpm, temperature 25 °C, light intensity of 1680 lumens at a color temperature of 6400K, without pH control for 8 days. The cellular concentrations obtained were 3.72x107 (Chlorella sp.), 1.36x107 (Scenedesmus sp.), 3.55x107 (Tetraselmis sp.), 5.74x107 (Nannochloris sp.) and 3.45x106 (Dunaliella salina), where the microalgae Chlorella sp., shows invasive capacity in drinking water cultivations. Applying the 2n-p fractional factorial design concept for the elemental composition of the microalgae and the cellular morphology, it was obtained 44.33% of C, 7.09% of H, 8.53% of N and 0.84% of S for the Chlorella sp. Resumo Foi avaliado o efeito das condições operacionais na produção de Chlorella sp. após a seleção do gênero Chlorella sp., Scenedesmus sp., Nannochloris sp., Tetraselmis sp. e Dunaliella salina. Microalgas foram inoculadas em água potável com adição de fertilizante NPK (N 24%, P 24% e K 18%), na concentração de 0,5 g/L, agitação de 150 rpm, temperatura de 25 °C, intensidade luminosa de 1.680 lúmens para uma temperatura de cor de 6.400 K, sem controle de pH por 8 dias. As concentrações celulares obtidas foram de 3,72 x 107 (Chlorella sp.), 1,36 x 107 (Scenedesmus sp.), 3,55 x 107 (Tetraselmis sp.), 5,74 x 107 (Nannochloris sp.) e 3,45 x 106 (Dunaliella salina), em que a microalga Chlorella sp. mostrou capacidade invasiva em cultivos de água potável. Aplicando o conceito de projeto fatorial fracionado 2n-p para a composição elementar da microalga e a morfologia celular, foram obtidos 44,33% de C, 7,09% de H, 8,53% de N e 0,84% de S para a Chlorella sp.

The nutrient composition of 15 commercially available microalgae powders of Arthrospira platensis, Chlorella pyrenoidosa and vulgaris, Dunaliella salina, Haematococcus pluvialis, Tetraselmis chuii, and Aphanizomenon flos-aquae was analyzed. The Dunaliella salina powders were characterized by a high content of carbohydrates, saturated fatty acids (SFAs), omega-6-polyunsaturated fatty acids (n6-PUFAs), heavy metals, and α-tocopherol, whereas the protein amounts, essential amino acids (EAAs), omega-3-PUFAs (n3-PUFAs), vitamins, and minerals were low. In the powder of Haematococcus pluvialis, ten times higher amounts of carotenoids compared to all other analyzed powders were determined, yet it was low in vitamins D and E, protein, and EAAs, and the n6/n3-PUFAs ratio was comparably high. Vitamin B12, quantified as cobalamin, was below 0.02 mg/100 g dry weight (d.w.) in all studied powders. Based on our analysis, microalgae such as Aphanizomenon and Chlorella may contribute to an adequate intake of critical nutrients such as protein with a high content of EAAs, dietary fibers, n3-PUFAs, Ca, Fe, Mg, and Zn, as well as vitamin D and E. Yet, the nutritional value of Aphanizomenon flos-aquae was slightly decreased by high contents of SFAs. The present data show that microalgae are rich in valuable nutrients, but the macro- and micronutrient profiles differ strongly between and within species.

Tetraselmis sp. and Nannochloropsis sp. are common marine microalgae used as substrates for production of biodiesel which is the third generation alternative energy. Recently, wavelength of light is believed to influence the growth of marine microalgae. In this investigation, two different types of light wavelength; red and blue which can influence the production of microalgae were investigated. The marine microalgae growths were observed in terms of biomass which was then measured using the UV-vis spectrophotometer. The results showed that both Tetraselmis sp. and Nannochloropsis sp. grow better in the blue light compared to the red light indicated by the higher absorbance readings.

Biomass productivity, photosynthetic efficiency and fatty acid profiles of the marine microalga Tetraselmis sp. in a turbidostat culture system using an outdoor photobioreactor are described. The maximum productivity depended on the units in which it was expressed; it reached 5·41 × 10−3 g/l/h in volumetric units, and 7·26g/m2/day in surface units, the former at the smallest culture depth (0·12m) and the latter at the greatest culture depth (0·25 m). Data from the experiments were adjusted to an equation for light limitation. The comparison of fatty acid composition at both depths showed that biosynthesis of polyunsaturated fatty acids (PUFAs), including eicosapentaenoic acid (EPA), was favoured when available light was low (0·17 m). Moreover, fatty acid 16:0 seemed to be an indicator of the type of limitation in the culture, i.e. nutrient or light limitation.

Marketable value of algal biomass has been increasing in recent years due to its wide range of applications. This study investigates the performance of a novel cylindrical interdigitated electrode array in electrocoagulation for the harvesting of marine microalgae (Tetraselmis sp.). The new electrode array is expected to exert a dielectrophoretic (DEP) force which would assist in the harvesting of the microalgae in the electrocoagulation process. Through numerical investigation, the induction of dielectrophoretic force was confirmed in the new electrode array. In this study, 10 min electrolysis time was found to be sufficient to harvest 82.4% microalgae with 1 cm electrode distance and 50 mA/cm2 current density. Furthermore, decreasing the electrode distance to 0.5 cm increased the algal harvesting efficiency to 96.18%. Energy analysis showed that the proposed electrode array shows 38% lower specific energy consumption than the conventional flat sheet electrode array.

Effects of food quality and quantity on certain fitness traits of G. pectrnatus were examined to develop methods of culture. Five generations were successfully reared on excess Isochrysis galbana, despite intense inbreeding. The effect of food quantity was tested using outcrossed offspring fed I. Galbana at four concentrations. Generation time (from hatching to egg) decreased from 43.2 days at 1 × 104 cells ml-1 (lowest concentration) to 19.6 days at 5 × 105 cells ml-1 (highest concentration). An increase occurred in female body length (0.88 to 1.01 mm) and egg number (21.2 to 51.3) with increasing food concentration, and the total number of adults produced per brood was significantly lower at 1 × 104 cells ml-1. Results on a Dunaliella tertiolecta diet were similar to those for I. Galbana at the one food concentration tested (1 × 105-2 × 105 cells ml-1); however, unlike I. galbana, D. tertiolecta did not sustain viable egg production and was therefore nutritionally inadequate for multiple generation culture. Larval mortality was high on diets of Tetraselmis chuii and Phaeodactylum tricornutum. Body lengths and egg numbers of cultured females fed I. Galbana were greater than those of the 'wild' parental females, thus indicating the suitability of the culture conditions.