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Laboratory- and Pilot-Scale Cultivation of Tetraselmis striata to Produce Valuable Metabolic Compounds

Laboratory- and Pilot-Scale Cultivation of Tetraselmis striata to Produce Valuable Metabolic Compounds

Article

Patrinou V, Patsialou S, Daskalaki A, Economou CN, Aggelis G, Vayenas DV, Tekerlekopoulou AG. Laboratory- and Pilot-Scale Cultivation of Tetraselmis striata to Produce Valuable Metabolic Compounds. Life. 2023; 13(2):480. https://doi.org/10.3390/life13020480 

Abstract
Marine microalgae are considered an important feedstock of multiple valuable metabolic compounds of high biotechnological potential. In this work, the marine microalga Tetraselmis striata was cultivated in different scaled photobioreactors (PBRs). Initially, experiments were performed using two different growth substrates (a modified F/2 and the commercial fertilizer Nutri-Leaf (30% TN—10% P—10% K)) to identify the most efficient and low-cost growth medium. These experiments took place in 4 L glass aquariums at the laboratory scale and in a 9 L vertical tubular pilot column. Enhanced biomass productivities (up to 83.2 mg L−1 d−1) and improved biomass composition (up to 41.8% d.w. proteins, 18.7% d.w. carbohydrates, 25.7% d.w. lipids and 4.2% d.w. total chlorophylls) were found when the fertilizer was used. Pilot-scale experiments were then performed using Nutri-Leaf as a growth medium in different PBRs: (a) a paddle wheel, open, raceway pond of 40 L, and (b) a disposable polyethylene (plastic) bag of 280 L working volume. Biomass growth and composition were also monitored at the pilot scale, showing that high-quality biomass can be produced, with important lipids (up to 27.6% d.w.), protein (up to 45.3% d.w.), carbohydrate (up to 15.5% d.w.) and pigment contents (up to 4.2% d.w. total chlorophylls), and high percentages of eicosapentaenoic acid (EPA). The research revealed that the strain successfully escalated in larger volumes and the biochemical composition of its biomass presents high commercial interest and could potentially be used as a feed ingredient.

Ocean4Biotech | Rome, May 2023

Large-scale cultivation of the microalgae Tetraselmis striata and utilization of the biomass produced as alternative raw material in fish feed

Roussos Efstratios1, Vasiliki Patrinou2, Tekerlekopoulou Athanasia2, Kampantais Dimitrios1, Triantaphyllidis George1 and Kotzamanis Yannis1

  • 1 Hellenic Centre for Marine Research, Institute of Marine Biology, Biotechnology and Aquaculture, Laboratory of Fish Nutrition and Omics Technologies
  • 2 Department of Environmental Engineering, University of Patras

 

The aim of this work was to evaluate the marine microalgae Tetraselmis striata biomass cultivated in drilling waters, as an ingredient in the feeds of European sea bass (Dicentrarchus labrax). The suitability of the produced biomass for incorporation into sea bass feeds was tested, following research on the optimization of the important functional parameters which affect its growth such as pH, temperature, photoperiod, and CO2 flow rate in large-scale production unit. A high fishmeal diet (32%) was served as a pelleted control diet, while a commercial T. striata biomass was incorporated in three diets at 2, 4, and 8% levels to substitute fishmeal, respectively. A fifth diet was formulated to include a 4% level of locally large-scale-produced T. striata. Fifteen sea bass fish with an average weight of 25.5 g were separated in 15 cylindroconical tanks with a volume of 1m3 (triplicates) in a programmable logic controller (PLC) controlled Recirculating aquaculture system (RAS). Fish were fed to apparent satiation (ad libitum) for approximately 2 months. The results showed that fish growth and health were satisfactory in all experimental diets and zootechnical indicators representative of fish size and species. The addition of microalgal biomass in the aquafeeds didn’t seem to affect the palatability of the experimental feeds. Commercial and produced biomass of the Tetraselmis striata strain didn’t present any statistically significant differences in terms of growth. In the targeted fishmeal substitution levels (2, 4 and 8%), the T. striata could successfully partially replace fish meal as the results showed a comparable growth within the 2-month feeding trial.

Ocean 4Biotech Rome 2023

Optimization of Cultivation Conditions for Tetraselmis striata and Biomass Quality Evaluation for Fish Feed Production

Optimization of Cultivation Conditions for Tetraselmis striata and Biomass Quality Evaluation for Fish Feed Production

 

Feature Paper

Patrinou V, Daskalaki A, Kampantais D, Kanakis DC, Economou CN, Bokas D, Kotzamanis Y, Aggelis G, Vayenas DV, Tekerlekopoulou AG. Optimization of Cultivation Conditions for Tetraselmis striata and Biomass Quality Evaluation for Fish Feed Production. Water. 2022; 14(19):3162. https://doi.org/10.3390/w14193162

Abstract

The marine microalgae Tetraselmis striata was cultivated in drilling waters with different salinities. Growth substrate optimization was performed while the effects of different pH, temperature, photoperiod and CO2 flow rate on biomass productivity and its composition were studied. Results showed that the strain grew better in 2.8% drilling waters employing the fertilizer Nutri-Leaf together with ΝaHCO3. A pH value of 8 resulted in high biomass productivity (79.8 mg L−1 d−1) and biomass composition (proteins 51.2% d.w., carbohydrates 14.6% d.w., lipids 27.8% d.w. and total chlorophylls 5.1% d.w.). The optimum cultivation temperature was found to be 25 ± 1 °C which further enhanced biomass productivity (93.7 mg L−1 d−1) and composition (proteins 38.7% d.w., carbohydrates 20.4% d.w., lipids 30.2% d.w., total chlorophylls 5.1% d.w.). Photoperiod experiments showed that continuous illumination was essential for biomass production. A 10 mL min−1 flow rate of CO2 lead to biomass productivity of 87.5 mg L−1 d−1 and high intracellular content (proteins 44.6% d.w., carbohydrates 10.3% d.w., lipids 27.3% d.w., total chlorophylls 5.2% d.w.). Applying the optimum growth conditions, the produced biomass presented high protein content with adequate amino acids and high percentages of eicosapentaenoic acid (EPA), indicating its suitability for incorporation into conventional fish feeds. In addition, this study analyzed how functional parameters may influence the uptake of nutrients by Tetraselmis.

Patrinou et al. (2022)

Optimization of Cultivation Conditions for Tetraselmis striata and Biomass Quality Evaluation for Fish Feed Production

Optimization of Cultivation Conditions for Tetraselmis striata and Biomass Quality Evaluation for Fish Feed Production

 

Feature Paper

Patrinou V, Daskalaki A, Kampantais D, Kanakis DC, Economou CN, Bokas D, Kotzamanis Y, Aggelis G, Vayenas DV, Tekerlekopoulou AG. Optimization of Cultivation Conditions for Tetraselmis striata and Biomass Quality Evaluation for Fish Feed Production. Water. 2022; 14(19):3162. https://doi.org/10.3390/w14193162

Abstract

The marine microalgae Tetraselmis striata was cultivated in drilling waters with different salinities. Growth substrate optimization was performed while the effects of different pH, temperature, photoperiod and CO2 flow rate on biomass productivity and its composition were studied. Results showed that the strain grew better in 2.8% drilling waters employing the fertilizer Nutri-Leaf together with ΝaHCO3. A pH value of 8 resulted in high biomass productivity (79.8 mg L−1 d−1) and biomass composition (proteins 51.2% d.w., carbohydrates 14.6% d.w., lipids 27.8% d.w. and total chlorophylls 5.1% d.w.). The optimum cultivation temperature was found to be 25 ± 1 °C which further enhanced biomass productivity (93.7 mg L−1 d−1) and composition (proteins 38.7% d.w., carbohydrates 20.4% d.w., lipids 30.2% d.w., total chlorophylls 5.1% d.w.). Photoperiod experiments showed that continuous illumination was essential for biomass production. A 10 mL min−1 flow rate of CO2 lead to biomass productivity of 87.5 mg L−1 d−1 and high intracellular content (proteins 44.6% d.w., carbohydrates 10.3% d.w., lipids 27.3% d.w., total chlorophylls 5.2% d.w.). Applying the optimum growth conditions, the produced biomass presented high protein content with adequate amino acids and high percentages of eicosapentaenoic acid (EPA), indicating its suitability for incorporation into conventional fish feeds. In addition, this study analyzed how functional parameters may influence the uptake of nutrients by Tetraselmis.

Patrinou et al. (2022)

XX INTERNATIONAL SYMPOSIUM ON FISH NUTRITION AND FEEDING TOWARDS PRECISION FISH NUTRITION AND FEEDING

CAROTENOID PROFILE OF TETRASELMIS STRIATA GROWN UNDER OPTIMAL CULTIVATION CONDITIONS IN A PILOT SCALE BIOREACTOR

 

Abstract

 

Microalgae are recognized as a valuable natural source of bioactive compounds, such as proteins, lipids, carotenoids and vitamins, for the aquaculture industry. The carotenoid profile of Tetraselmis striata, laboratory cultivated at different pH, temperature and photoperiod, was analyzed using Ultra High-Pressure Liquid Chromatography (UPLC) coupled with a mass spectrometer (Q-TOF). Identification and quantification of the carotenoid profile were performed using standard solutions (astaxanthin, lutein & zeaxanthin, canthaxanthin, echinenone, lycopene, b-cryptoxanthin, b-carotene), and an internal standard (trans-β-apo-carotenal). A carotenoid extraction protocol was developed and chloroform was selected as the extraction solvent. A saponification protocol was applied for the successful removal of chlorophylls, lipids, and esters, assisting in the quantification of b-carotene, canthaxanthin, and b-cryptoxanthin. However, this method had a notable deterioration effect on the remaining carotenoids. Consequently, a simultaneous extraction protocol without saponification was followed to quantify the rest of the carotenoids. Α scale-up cultivation of T. striata was conducted in a 40 L capacity paddlewheel stainless steel raceway pond (110.5 x 61 x 20 cm, external length, width and height, respectively), by applying the optimal cultivation conditions found in previous laboratory trials (continuous illumination, 25oC and pH8), in terms of its high biomass productivity (92.5 mg L-1 d-1). Carotenoids detected in T. striata were b-carotene (7063.4 mg/kg dry biomass), lutein & zeaxanthin (1692.8 mg/kg), echinenone (190.9 mg/kg), b-cryptoxanthin (40.7 mg/kg), astaxanthin (33.5 mg/kg) and canthaxanthin (2.12 mg/kg), while lycopene was not detected in any of the analyzed samples. The results showed that T. striata can be considered a potential natural source of carotenoid compounds.

ABSTRACT

ABSTRACT (PDF)

POSTER PRESENTATION (PDF)

POSTER PRESENTATION (POWERPOINT)

1st International Conference on Sustainable Chemical and Environmental Engineering

Cultivation of marine microalgae – Production of biomass and high value added products

Introduction

Marine microalgae are considered versatile cellular factories that produce a plethora of metabolic compounds. The high value added components they produce is a broad category containing mainly lipids, carbohydrates and proteins (Ma et al., 2020). Lipids from marine microalgae are significant as they are a major source of important poly-unsaturated fatty acids (PUFAs) such as omega-3 [EPA (C20:5), DHA (C22:6), α-Linolenic (C18:3(n-3)] and omega-6 (Dammak et al., 2016). Additionally, extracted high value products can be utilized in many different commercial applications including biofuels, health food supplements, aquafeeds, cosmetics, and pharmaceuticals. The addition of microalgal biomass into fish diets is beneficial for fish as it leads to improved growth and fillet quality, increased deposition of proteins in muscle tissue, improved resistance to disease, and higher fatty acid content (Shah et al., 2018).

In this work, four marine microalgae were studied (Nannochloropsis sp., Nannochloropsis oculata, Isochrysis galbana and Tetraselmis striata). Each is currently of high interest for aquafeeds and has the potential to produce important lipids. The aim was to select the most suitable microalga for full-scale production. The strains were cultivated in drilling seawaters, and specific growth rate and biomass productivity were the determining parameters for the selection of the optimum microalga. Growth medium optimization was then performed for the selected strain. Subsequent fatty acid analysis revealed significant EPA and PUFAs contents when the microalga was cultivated in the optimized growth medium.

 

Materials and methods

Dry cell biomass and lipid content were determined gravimetrically (mg L-1) as Total Suspended Solids (TSS) according to Standard Methods (1998). Biomass productivity expressed in mg L-1 d-1 was calculated following Gonçalves et al. (2016), while maximum specific growth rate (d-1) was calculated following Tsolcha et al. (2017). Lipid extraction was carried out following Folch (1957) and the fatty acid profile was determined according to AFNOR (1984).

 

Results and discussion

The microalgal strains were cultivated in 38 ‰ drilling waters originating from the commercial fish farm PLAGTON S.A. (Western Greece). The seawaters had no nutrient load and nutrient supplementation was essential to sustain growth. Only N and P, at a ratio of about 5:1, were added to the drilling waters, with the aim of reducing production costs in potential future full-scale cultivations. Tetraselmis striata, the Chrysophyceae Isochrysis galbana and the two Nannochloropsis species, were cultivated under conditions of continuous illumination of 56 μmol m−2 s−1, and unregulated temperature and pH. The biomass efficiencies achieved for the different strains are presented in Table 1.

 

Table 1. Biomass productivities and specific growth rates obtained from the four marine microalgae.

Strain Biomass productivity

(mg L-1 d-1)

Specific growth rate (d-1)
Nannochloropsis sp. 23.2 0.073
Nannochloropsis oculata 27.0 0.077
Tetraselmis striata 40.2 0.101
Isochrysis galbana 95.2 0.366

 

The Nannochloropsis strains presented the lowest biomass productivities and specific growth rates. Although Isochrysis galbana exhibited the highest biomass productivity it was not selected as the optimum species, because of the difficulty in maintaining the culture’s purity. Microscopic observations showed that the strain was susceptible to contamination even in laboratory-scale experiments and thus it was not considered suitable for full-scale cultivations. Therefore, Tetraselmis striata was selected as the optimum species, as it presented satisfactory biomass yields under conditions of high salinity and low nutrient availability.

Substrate optimization was performed to further enhance growth. A medium of double N:P ratio (12:1) was studied in 38 ‰ and 29 ‰ seawaters. The highest biomass productivity (47.6 mg L-1d-1) was recorded in the 29 ‰ medium indicating that T. striata prefers lower salinities. The effect of medium composition on growth was also evaluated in 29 ‰ seawater by further enriching the medium with the commercial fertilizer Nutri-Leaf (30% TN, 10% P, 10% K) together with NaHCO3. Using Nutri-Leaf significantly enhanced the recorded biomass productivity (79.8 mg L-1d-1 with a corresponding growth rate of 0.266 d-1), while the produced biomass also contained high lipid contents of up to 27.8%  dry weight.

Finally, fatty acid analysis of the biomass generated under the optimum cultivation conditions showed that T. striata produced high EPA (27.6%) and PUFAs (33.2%) contents.

 

Conclusions

The results of this study indicate that the marine microalgae T. striata is suitable for full-scale applications and can achieve significant biomass yields. Additionally, the strain is an important Pufa producer and its high nutritional value shows its suitability for incorporation into aquafeeds.

 

ABSTRACT

POSTER PRESENTATION

Protection and Restoration of the Environment XVI

LABORATORY AND PILOT-SCALE CULTIVATION OF TETRASELMIS STRIATA UNDER OPTIMIZED GROWTH CONDITIONS FOR FISH FEED PRODUCTION

 Abstract

In this work Tetraselmis striata was cultivated in drilling waters (salinity 29 ‰) obtained from the commercial fishery of Plagton S.A.. Previous studies had shown that the microalga displayed optimum growth using 0.2 g L-1 of the commercial fertilizer Nutri-Leef (30%-TN, 10%-P, 10%-K) together with 0.18 g L-1 of NaHCO3 at a pH value of 8. The effects of temperature, photoperiod and CO2 flow rate on growth and biomass composition of T. striata were also examined in laboratory conditions. The temperatures of 19±1oC, 25±1oC and 28±1oC were studied under continuous illumination (24:0, L (Light): D (Dark)). The highest biomass productivity of 93.7 mg L-1 d-1 was achieved at 25oC and high protein (49.9%), lipid (23.5%), carbohydrate (19.6%) and pigment contents (5.1%) were also recorded at this temperature. Further experiments were conducted at 25oC studying the photoperiods of 20:4, 18:6, 12:12 L:D. Results revealed that biomass was significantly affected by light absence and biomass productivity gradually reduced as the dark periods lengthened. The metabolic products exhibited higher accumulation rates under continuous illumination which was selected as optimum. The effect of carbon source was also estimated employing pure CO2 at different flow rates (10 mL min-1, 20 mL min-1, 90 mL min-1). T. striata could not tolerate the high flow rate of 90 mL min-1 while high biomass productivities (87.5 mg L-1 d-1) were recorded at 10 and 20 mL min-1. Pilot-scale experiments at the optimum growth conditions were conducted in a raceway pond of 40 L capacity. Biomass productivity reached 93.5 mg L-1 d-1, while protein, carbohydrate, lipid and pigment contents were 48.8%, 21.6%, 28.1%, 4.8% respectively. In both laboratory- and pilot-scale experiments, analysis of amino acids and fatty acids showed that the produced biomass is suitable for incorporation into conventional fish feeds.

ABSTRACT

POSTER PRESENTATION

 

 

13ο Πανελληνίο Επιστημονικό Συνέδριο Χημικής Μηχανικής

ΒΕΛΤΙΣΤΟΠΟΙΗΣΗ ΤΩΝ ΣΥΝΘΗΚΩΝ ΑΝΑΠΤΥΞΗΣ ΤΟΥ ΘΑΛΑΣΣΙΝΟΥ ΜΙΚΡΟΦΥΚΟΥΣ TETRASELMIS
STRIATA
KAI ΠΟΙΟΤΙΚΟΣ ΧΑΡΑΚΤΗΡΙΣΜΟΣ ΤΗΣ ΠΑΡΑΓΟΜΕΝΗΣ ΒΙΟΜΑΖΑΣ ΜΕ ΣΚΟΠΟ ΤΗΝ
ΠΑΡΑΓΩΓΗ ΙΧΘΥΟΤΡΟΦΗΣ

ΠΕΡΙΛΗΨΗ
Στην παρούσα εργασία μελετήθηκε η ανάπτυξη του Tetraselmis striata σε νερά γεώτρησης
αλατότητας 29 ‰, τα οποία προέρχονταν από τις εγκαταστάσεις της ιχθυοκαλλιέργειας PLAGTON
S.A.. Στοχεύοντας στην αύξηση της παραγωγής και στη βελτίωση της ποιότητας της παραγόμενης
βιομάζας μελετήθηκε κατά την ακόλουθη σειρά η επίδραση του υποστρώματος, του pH, της
θερμοκρασίας, της φωτοπεριόδου και της παροχής CO
2. Από τα εξεταζόμενα υποστρώματα
(τροποποιημένο F/2, εμπορικό λίπασμα Nutri-Leef (30%-TN, 10%-P, 10%-K) χωρίς και με προσθήκη
NaHCO
3,) το Nutri Leef παρουσία NaHCO3 παρουσίασε υψηλές τιμές παραγωγικότητας βιομάζας
(84.2
mg L-1 d-1). Στη συνέχεια εξετάστηκε η επίδραση του pH (7 και 8), με την τιμή του 8 να
χαρακτηρίζεται ως βέλτιστη (παραγωγικότητα βιομάζας
79.8 mg L-1 d-1 με υψηλές συγκεντρώσεις
λιπιδίων, πολυσακχαριτών και χρωστικών
) και να χρησιμοποιείται για όλα τα επόμενα πειράματα.
Πειράματα έλαβαν χώρα και σε τρεις διαφορετικές θερμοκρασίες, 19 ± 1, 25 ± 1 και 28 ± 1
oC υπό
συνεχή φωτισμό (24:0, L (Φως): D (Σκοτάδι)). Η θερμοκρασία των 25
oC, η οποία κρίθηκε ως
βέλτιστη παρουσίασε την υψηλότερη παραγωγικότητα βιομάζας (93.7 mg L
-1 d-1), αλλά και την
υψηλότερη περιεκτικότητα σε βιοενεργά συστατικά. Στην συνέχεια μελετήθηκε η επίδραση της
φωτοπεριόδου στους 25
oC εξετάζοντας τις περιόδους των 20:4, 18:6, 12:12 L:D. Τα αποτελέσματα
έδειξαν πως η αύξηση των σκοτεινών περιόδων επέφερε μείωση της παραγωγικότητας της
βιομάζας. Τέλος, μελετήθηκε η επίδραση του καθαρού CO
2 στην ανάπτυξη του μικροφύκους
εξετάζοντας τους ρυθμούς παροχής 10, 20 και 90 mL min
-1, με την υψηλότερη τιμή
παραγωγικότητας βιομάζας (87.5 mg L
-1 d-1) να παρουσιάζεται στην παροχή των 10 mL min-1.
Ανάλυση του προφίλ των αμινοξέων και των λιπαρών οξέων έδειξε επαρκές αμινοξικό προφίλ με
υψηλό πρωτεινικό περιεχόμενο και σημαντικό ποσοστό πολυακόρεστων λιπαρών οξέων
αντιστοίχα, καταλήγοντας στο συμπέρασμα ότι η παραγόμενη βιομάζα είναι κατάλληλη για
ενσωμάτωση σε ιχθυοτροφές.

ΠΕΡΙΛΗΨΗ

ΠΛΗΡΗΣ ΠΕΡΙΛΗΨΗ

ΠΑΡΟΥΣΙΑΣΗ ΣΤΟ ΣΥΝΕΔΡΙΟ

9th International Conference of MIKROBIOKOSMOS

Abstract

Microalgae are an exceptional source of polyunsaturated fatty acids, vitamins, proteins, carbohydrates and amino acids that can improve fish growth. Their biomass nutritional value is determined by these nutrients and therefore, parameters affecting growth and biomass composition (pH, growth media, temperature and photoperiod) are often adjusted.

Tetraselmis striata was cultivated in drilling waters (salinity 29 ‰) obtained from the commercial fish farm Plagton S.A.. Previous studies showed that the microalga displayed optimum growth using 0.2 gr L-1 of the commercial fertilizer Nutri-Leef (30%-TN, 10%-P, 10%-K) together with an inorganic carbon source (0.18 gr L-1, NaHCO3) at a pH value of 8. Under these optimized conditions, the effects of photoperiod and temperature on growth and biomass composition were evaluated. Initially, the photoperiod effect was studied at a temperature of 25 ±1oC. Tetraselmis was cultivated in constant light (24:0, L(Light):D(Dark)) and then 20:4, 18:6, 12:12 L:D exposure. The results revealed that biomass was significantly affected by light absence. The highest productivity of 93.7 mg L-1 d-1 was noted at 24:0 L:D but gradually reduced as the dark periods lengthened. Protein contents ranged between 50.3 to 49.9%, while only at 12:12 L:D were lower at the value of 42.9 %. Lipid contents were 23.5 to 29.7%, while carbohydrate contents were ranged from 14.6-19.7%. Pigments also exhibited higher accumulation rates under 24 h light photoperiod (5.1%) and thus continuous illumination was selected as the optimum growth condition. The growth temperatures of 19±1oC and 28 ±1oC were then studied. Recorded biomass productivity values were 69.3 and 55.0 mg L-1 d-1 respectively, while protein (43.6-40%) and pigment (3.4-2.7%) contents reduced slightly under these conditions. Thus, optimum growth and biomass composition for Tetraselmis is achieved at constant light and at 25oC. High quality biomass important for fish growth can be produced under these conditions.

Abstract

Poster Presentation

7th International Conference on Industrial and Hazardous Waste Management

Abstract

Aquaculture currently faces significant challenges related to the high cost and reduced availability of fishmeal and fish oil for inclusion in the diets of farmed fish. The use of microalgae as an alternative raw material for fish feed presents a great interest as microalgae are an exceptional source of nutrients, such as polyunsaturated fatty acids, proteins and amino acids which can improve fish growth and fillet quality. To improve the microalgal biomass production and increase biomass enrichment in specific nutrients, important functional growth parameters must be optimized.

The marine microalga Tetraselmis striata was cultivated in different drilling waters originating from the facilities of Plagton S.A a commercial fish farm located in Western Greece which naturally have different salinities. The waters employed in the present study were taken straight from the drills and presented no nutrient load, thus the supplementation of minerals was essential for microalga’s growth. The effects of salinity, pH, and initial nitrogen and phosphorus concentration ratios on the specific growth rate and ability of the strain to biosynthesize proteins, lipids, polysaccharides and pigments were studied. Laboratory-scale experiments were performed under non-aseptic and suspended growth conditions. T. striata growth was initially examined in drill water with high salinity (38‰) that further was enriched with nitrogen and phosphorous and with or without the addition of trace elements. The results revealed low biomass productivities ranging from 32.2 to 40.0 mg L-1 d-1 with specific growth rates varying from 0.062 to 0.100 d-1 and lipid contents of 9.3-24.0% (Table 1). It was concluded that these low biomass efficiencies were probably due to high salinity and the chemical composition of growth medias suppemented in the 38‰ waters. Consequently, growth of the microalgae was evaluated in less saline drilling waters (29‰) but supplemented with different nutrient media. The waters was enriched with a modified F/2 substrate or the commercial fertilizer Nutri-Leef (composed with 30%-TN, 10% -P, 10% -K) with or without the addition of an inorganic carbon source (NaHCO3). The resulting maximum biomass productivities ranged from 69.3 to 85.0 mg L-1 d-1 while lipid content was 10.8-13.7% (Table 1). Nutri-Leef 30-10-10 with the addition of inorganic carbon produced the highest biomass yields and was therefore used as the matrix to study the effect of pH. Different pH levels of 7 and 8 were tested and pH 8 presented significant biomass productivity yields (79.81 mg L-1 d-1 with a specific growth rate of 0.156 d-1) and a maximum oil content of 26.4% (Figure 1).

The biomass of T. striata produced under the above optimum growth conditions was rich in carbohydrates, proteins and pigments (36.5%, 38.25% and 3.6%, respectively) (Table 2). Additionally, the lipids of the microalga biomass contained 10-14% EPA, indicating its high value  for incorporation into conventional fish feed.

Short_Abstract

Full _Abstract

Poster_ presentation

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