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Globalno zagrijavanje kritičan je problem koji utječe na naš planet i uzrokuje značajne promjene u temperaturi i klimi na Zemlji. Budući da su biljke poikilotermni organizmi, najznačajniji utjecaj globalnog zatopljenja na život biljaka jesu sposobnost kratkotrajne aklimatizacije, kad su temperaturni skokovi značajni i dugotrajna adaptacija na novonastale klimatske uvjete uzrokovane povećanjem temperature. Toplinski stres kritičan je okolišni čimbenik koji može imati ozbiljan utjecaj na rast i razvoj biljaka. Kada su biljke izložene visokim temperaturama tijekom duljeg razdoblja, to može dovesti do širokog spektra fizioloških i biokemijskih promjena, što u konačnici može dovesti do smanjenog rasta i reprodukcije. Jedno od potencijalnih rješenja koja su predložena za ublažavanje utjecaja globalnog zagrijavanja je uporaba algi, posebno vrste mikroalgi Nannochloropsis sp., koje su poznate po svojoj visokoj fotosintetskoj učinkovitosti i stopama rasta. Međutim, globalno zagrijavanje također ima značajne implikacije za alge, uključujući Nannochloropsis sp. čiji molekularni mehanizmi odgovora na stres uključuju aktivaciju kaskade proteina koja u konačnici rezultira sintezom proteina toplinskog udara (Heat shock protein-Hsp). Hsps su grupni naziv za nekoliko različitih evolucijski konzerviranih obitelji proteina od kojih su neki molekularni šaperoni. Hsp70 predstavlja obitelj šaperona čija se koncentracija povećava u stanicama prilikom toplinskog stresa te isti pridonose pravilnom smatanju i stabilizaciji proteina. Bioinformatičkom analizom genoma alge Nannochloropsis sp. utvrdilo se postojanje deset sekvenci proteina iz Hsp70 obitelji i određena su njihova svojstva na temelju fizikalno-kemijskih svojstava, genomskih lokacija, predviđena je stanična lokalizacija pojedinih proteina te su određeni filogenetski odnosi među njima. Global warming is a critical problem that affects our planet and causes significant changes in temperature and climate on Earth. Since plants are poikilothermic organisms, the most significant impacts of global warming on plant life are the ability to acclimate to short-term temperature changes, and long-term adaptation to new climate conditions caused by increased temperature. Heat stress is a critical environmental factor that can have a serious impact on plant growth and development. When plants are exposed to high temperatures for an extended period, it can lead to a wide range of physiological and biochemical changes, ultimately resulting in reduced growth and reproduction. One potential solution proposed to mitigate the impact of global warming is the use of algae, especially the microalga species Nannochloropsis sp., known for their high photosynthetic efficiency and growth rates. However, global warming also has significant implications for algae, including Nannochloropsis sp., whose molecular response mechanisms to stress conditions involve the activation of a protein cascade that ultimately results in the synthesis of heat shock protein (Hsp). Hsps are a group name for several evolutionarily conserved families of proteins, some of which are molecular chaperones. Hsp70 represents a family of chaperones whose concentration increases in cells during heat stress, contributing to proper protein folding and stabilization. Bioinformatic genome analysis of Nannochloropsis sp. algae revealed the existence of ten protein sequences from the Hsp70 family, and their properties were determined based on their physicochemical properties, genomic locations, predicted cellular localization of individual proteins, and their phylogenetic relationships.

Separation of microalgae of various sizes and shapes is an important process that enables subsequent production of useful compounds. Herein, the separation of microalgae was accomplished using a magnetite-containing gel (42 μm) packed into a column. An algal suspension was injected into the top of the gel bed, after which water was passed through the column. The pressure generated during the process caused the lower domain of the gel bed to deform, resulting in narrowed gaps between the gel beads. When a suspension of Nannochloropsis sp. (0.0069-0.69 g L-1) was loaded and water was passed through the column at an applied pressure of 0.01-0.10 MPa, the majority of microalgae were captured within the upper domain of the gel bed, while only 20% were captured within the lower domain. The amount of Nannochloropsis sp. captured was expressed by an ordinary differential equation to determine the capture coefficient, K, and the maximum capture amount, Qmax. As pressure increased, gel gaps narrowed, K increased, and Qmax decreased because of a reduction in the number of effective capture sites upon compaction of the gel. When a mixed suspension of Anabaena sp., Monoraphidium sp., and Desmodesmus sp. (0.069 g L-1 each) was injected into the gel bed at an applied pressure of 0.01 MPa, only Anabaena sp. was captured at the bottom of the gel bed. This device can be applied for the separation of microalgae in rivers and the sea.

Mikroalge rodova Nannochloropsis i Isochrysis predstavljaju sirovinu koja se može koristiti za proizvodnju energije. Cilj ovog rada bio je opisati uzgoj mikroalgi rodova Nannochloropsis i Isochrysis u različitim tehnološkim sustavima te laboratorijskim metodama istražiti njihove kemijske i fizikalne karakteristike za preliminarnu procjenu energetskog potencijala za proizvodnju bioplina i biodizela. Analizom uzoraka mikroalgi Nannochloropsis oculata, utvrđene su srednje vrijednosti sadržaja vode 95,28 %, sadržaja pepela 76,5 %, sadržaja masti 0,3271 %. Salinitet otopine uzoraka mikroalge N. oculata iznosio je 37,114 ppt. Utvrđena je kemijska potrošnja kisika (KPK), od ostataka mikroalgi nakon proizvodnje biodizela, koja je iznosila 1244 mg/L. Analizom uzoraka mikroalgi Isochrysis galbana, utvrđene su srednje vrijednosti sadržaja vode 95,42 %, sadržaja pepela 77,91 %, sadržaja masti 0,3395 %. Salinitet otopine uzoraka mikroalge I. galbana je iznosio 36,516 ppt. Utvrđena je kemijska potrošnja kisika (KPK), od ostataka mikroalgi nakon proizvodnje biodizela, koja je iznosila 999 mg/L. Može se zaključiti da postoji potencijal u proizvodnji biogoriva iz mikroalgi, te da je moguća integrirana kružna proizvodnja. Međutim, potrebno je optimizirati sustav proizvodnje kako bi prinosi bili što veći, a troškovi proizvodnje što manji. Nannochloropsis and Isochrysis microalgae represent a raw material that can be used for energy production. The aim of this research was to describe the cultivation of the Nannochloropsis and Isochrysis microalgae in different technological systems and to determine their chemical and physical characteristics using laboratory methods for a preliminary assessment of the energy potential for the production of biogas and biodiesel. Analysing the Nannochloropsis samples, the average values of water content was measured at 95.28 %, ash content at 76.5 %, fat content at 0.3271 % were determined. The solution salinity of the Nannochloropsis samples was measured at 37.114 ppt. The chemical oxygen consumption (COD) of microalgae residues after biodiesel production was determined, which was 1244 mg/L. Through the analysis of the Isochrysis galbana samples, the average values of water content was measured at 95.42 %, ash content at 77.91 %, fat content at 0.3395 % were determined. The solution salinity of the I. galbana samples was measured at 36,516 ppt. The chemical oxygen consumption (COD) of microalgae residues after biodiesel production was determined, which was 999 mg/L. It can be concluded that there is potential in the production of biofuel from microalgae, and that integrated circular production is possible. However, it is necessary to optimize the production system so that yields are as high as possible and production costs are as low as possible.

Leachate from landfill contains concentrated nutrients that may enter the terrestrial and aquatic environment, including nearby coastal areas. The nutrient contaminants eventually bring harm to marine organisms, including microalgae. This study was performed to investigate the growth of two green microalgal species, i.e. Chlorella sp. and Nannochloropsis sp. in diluted landfill leachate. Besides, the ability of nutrient removal by these microalgal was also explored from the changes of chemical oxygen demand (COD) and nutrients content. The initial and final concentrations of COD, NH3-N, and PO43- in the diluted leachate (5%, 10% and 15%) were measured and the growth patterns of these species were determined by counting the cell numbers for 12 days. Comparison of these microalgae showed that the growth rate of Nannochloropsis was significantly higher compared to Chlorella in all leachate concentrations. Leachate at 5% enhanced the growth of both microalgae, while leachates at 10% and 15% decreased their growth as early as at the beginning of the test. It is apparent that the less concentrated leachate discharged into seawater would not pose any toxicity to the environment and would not bear adverse effect to microalgae yet could promote their growth. This study also revealed that the microalgae could remediate leachate pollution by its ability of nutrient removal; thus, leading to the potential application in wastewater bioremediation, including industrial waste and palm oil mill effluent.

Microalgae have been immobilized in alginate matrixes for the ease of harvesting of the microalgae. However, not all microalgae thrive when immobilized. Immobilized cells are sensitive to the micro-environment in alginate matrixes. Hence, this study aims to improve the growth of immobilized cells and also ammoniacal-nitrogen (NH4 +-N) removal by adding growth medium in alginate beads during the immobilization process. Different strength of the Guillard’s f/2 medium (0%, 30%, 50%, and 100%) was enriched in alginate beads inoculated with Nannochloropsis sp. The immobilized cells were then cultivated in seawater with 1000 µM NH4 +-N as the sole nitrogen source. The growth and NH4 +-N uptake by immobilized cells enriched with different strength of f/2 medium were compared. There were no significant differences on specific growth rate and specific uptake rate of immobilized cells after nutrient enrichment in alginate beads. However, maximum cells attained and maximum NH4 +-N removed increased when strength of f/2 medium enriched in alginate beads was increased. Significantly higher maximum cells attained and maximum NH4 +-N removal were found in immobilized cells enriched with half strength of f/2 medium than those without nutrient enrichment. The present study demonstrated that nutrient enriched in alginate beads can be used by immobilized cells, and subsequently improves the performance of immobilized cells in marine water treatment and production of microalgal biomass simultaneously.

Lipid mesophases are lyotropic liquid crystalline systems which differ from liposomes and other globular aggregates in dilute regimes due to their inner ordering. It is known that natural lipids enable to obtain a rich variety of nanosystems and many of them have been proposed as delivery agents for bioactive compounds. Due to their packing parameters, several classes of lipids found in natural sources are able to self-assemble into nonlamellar structures. Among lipids occurring in plants and algae, triglycerides display this tendency. In the present study we examine new nanosystems built with lipids extracted from the marine microalga Nannochloropsis sp and their use as carriers for lipophilic antioxidants. The antioxidants studied, curcumin and tocopherol were encapsulated with high rate in the carriers. The physico-chemical characterization of plain and loaded vectors showed their structure and localization site, as well as the structure-functionality relationship related to potential drug delivery. The results show that the cargo molecules play an active role in driving the interactions which characterize the overall structure of the aggregates. The systems studied showed several coexisting mesophases, the most predominant structure being of cubic symmetry.

Palm oil mill effluent (POME) has high chemical oxygen demand (COD), thus requires effective treatments to environmentally benign levels before discharge. In this study, immobilized microalgae cell...

This study was carried out to evaluate the population growth and egg ratio of Brachionus rotundiformis by feeding with three different diets, i.e., live microalgae Nannochloropsis sp., Baker’s yeast, and powdered spirulina. A total of nine conical flasks of 1 L volume were divided into three treatment groups for determining the feeding performance for eight consecutive days. Each experimental group was stocked with B. rotundiformis at an initial density of 10 ind. mL−1. Water temperature, pH, salinity, and light were maintained at (24–29) °C, (7.5–8.5), 30 ppt, and 4000 lx, respectively. Feed was provided twice per day at 9:00 AM and 7:00 PM. The highest mean (±SE) population growth of rotifer was achieved at the end of the culture period (on the 8th day) fed live Nannochloropsis sp. (122 ± 12 ind. mL−1), which was significantly higher compared to the Baker’s yeast and powdered spirulina (p 0.05). The highest mean (±SE) egg ratio of B. rotundiformis was observed in the live Nannochloropsis fed group (0.89 ± 0.01) at the end of the rearing period, which was significantly higher than that of Baker’s Yeast and powdered Spirulina fed group (p

MicroalgaeNannochloropsissp. is a widely recognized renewable biodiesel feedstock. The ability of this microalgae to absorb CO2constitutes an added value toward reducing global warming. However, the process of optimizing its growth still involves many challenges. Photoinhibition, which takes places during microalgae cultivation when using continuous lighting, constitutes an unresolved problem. Therefore, the optimum light/dark cycle method is considered necessary. The experiments were conducted using a designed, tubular airlift photobioreactor and blue, energy-saving, light-emitting diode (LED) lights for the purpose of internal illumination. We observed that a 45:15 min (light:dark) cycle increased the production ofNannochloropsissp. biomass significantly, with a cell density, wet weight, and lipid content of 17 × 106cell/ml, 7.11 g, and 10.1% dry weight, respectively. By using the blue LED lights, our designed, airlift photobioreactor increased cell growth by 70% compared to the growth ofNannochloropsissp. in nature and produced 61 times higher lipid content compared toNannochloropsissp. that is exposed to natural light.

Microalgae are regarded as a promising feedstock for biofuels and value-added products but still suffer from an inefficient lipid extraction process. In the present study, a simple and energy-efficient extraction method is demonstrated to extract oil directly from the wet cake (260 g/L) of Nannochloropsis sp. with an assist from the high shear mixer (HSM). After the initial solvent screening, the composition of co-solvent and operating conditions were optimized according to lipid composition and extraction yield. The high shear-assisted extraction process was found to achieve 83% lipid extraction yield (94% for EPA) in 5 min and 95% yield (100% for EPA) in 30 min with minimal amounts of solvents (0.9 ml hexane, 0.39 ml ethanol, and 0.057 ml sulfuric acid for 1 g of wet cell) at 8000 rpm, 55 °C. In comparison with various two-step wet extraction methods, the HSM offers the most economical extraction in terms of specific energy consumption of 1.38 MJ/kg dry cell. Therefore, the HSM can be considered as an attractive alternative to conventional extraction methods, providing a new paradigm of wet extraction for microalgae.

Oleaginous microalgae can accumulate large amounts of storage lipids that have many potential applications such as in the production of biodiesel and health products. All of the energy for the synthesis of lipids in microalgae is derived from photosynthesis. To date, however, the quantitative relationship between photosynthesis and lipid accumulation rate in microalgae is still unclear. In this study, Nannochloropsis sp. was selected to explore this relationship by investigating changes in lipid accumulation, photosynthetic efficiency, and the electron transport chain under nutrients limitation and replenishment. The results of the study demonstrated that lipids were the main form of storage of carbon and energy for this microalga. The alternative electron transport chain played an important role in photo-protection and lipid accumulation. The photosynthetic efficiency of this microalga showed a strong correlation with lipid accumulation rate (R2 = 0.959), with higher photosynthetic efficiency translating to higher lipid accumulation rates during the lipid accumulation stage of the growth cycle. The results of the present study indicated that nutrient depletion might not be the best signal to understand when microalgae begin to accumulate oil, as it appears that photosynthetic efficiency also has a large role in the rate of oil accumulation. Additionally, the study shows that excessive light might not be needed in later stages of growth for lipid accumulation, which in turn would alleviate the damage to microalgae caused by strong light making large-scale cultivation more cost-effective.

Nannochloropsis sp. is a green alga that is widely used in the aquaculture industry as a feed in Malaysia, but genetic engineering studies of this alga are still underexplored even though there is a growing interest in microalgae genetic engineering for various industrial purposes. This study aims to investigate the efficiency of three transformation methods normally done on microalgae, namely polyethylene glycol (PEG), electroporation, and glass beads on Malaysian indigenous Nannochloropsis sp. using two commercially available plasmids, pUC19 and pGEM-T easy vector as well as an amplicon of ampicillin resistance (AMPR) gene. In this study, out of three transformation methods tested, positive transformants of Nannochloropsis sp. were successfully obtained via electroporation method. Further verification via polymerase chain reaction (PCR) and sequencing confirmed that the electroporation method was found to be the sole successful method in producing transgenic lines of our locally isolated Nannochloropsis sp. Results from this study proved the efficiency of electroporation for delivery of transgene to this green alga which has been reported to be tedious. The described method also provides the gateway for developing Nannochloropsis sp. as a delivery system to aquatic organism due to its importance in the industry.

In this study, microalgal phenolic extracts (MPE) of Nannochloropsis sp. and Spirulina sp. were tested in in vitro experiments and, in comparison with synthetic fungicides, in field experiments, for their ability to control Fusarium graminearum development and limit deoxynivalenol (DON) contamination. In in vitro experiments, the Nannochloropsis and Spirulina extracts inhibited fungal biomass by 34 and 25%, respectively, compared with the untreated control. This effect was confirmed by a reduction in ergosterol production (-80% for Nannochloropsis and -75% for Spirulina) and in DON content (-97% for Nannochloropsis and -62% for Spirulina). In field experiments, application of the fungicide prothioconazole and prothioconazole + tebuconazole resulted in control of Fusarium head blight (FHB) and foliar disease, leading to a significant increase in grain yield (+13%) and a reduction in DON content (-46%) compared to the untreated control. The application of MPE at wheat flowering reduced the severity of FHB compared with the control (-35% for Spirulina and -39% for Nannochloropsis). However, the MPE did not significantly control foliar diseases (Septoria tritici blotch) and therefore did not enhance the grain yield. Moreover, no effect in reducing the DON content in comparison to the control was observed in the field. In view of that, the use of MPE in wheat fields as real alternatives to conventional fungicides requires the discovery of solutions to empower their persistence and efficacy.

To improve the quality of bio-oil, hydration-calcination CaO (HC CaO) was used to deoxygenate pyrolysis bio-oil from Nannochloropsis sp. As an economically and environmentally promising mic...

International audience; This study investigated the impact of seasonal variations on the productivity of Nannochloropsis oculata culture, cultivated in an outdoor pilot scale open pond raceway over 16 months. The 2.5 m3 pilot (i.e. water depth of 20 cm) was operated under phototrophic conditions in a simulated marine environment at 50 g.L−1 of salinity. Results revealed that culture growth rates, doubling times and productivity were highly impacted by weather conditions with a good reproducibility of seasonal features. During summer, growth rate (i.e. 0.15 d−1) was higher than in winter (i.e. +300%) and in spring-autumn (i.e. +40%). Average areal productivities were higher during summertime (i.e. 13.2 t.ha−1.y−1 or 3.61 g.m−2.d−1) compared to those of winter (i.e. +264%) and autumn-spring conditions (i.e. +90%). Monthly correlation analysis revealed also a significant correlation between productivity and weather conditions (i.e. higher than 0.85), especially during culture periods not affected by microbial contamination, while daily correlation analysis showed that microalgae have a relative long-time spread response (i.e. about 10 days) to change in weather conditions. Therefore, the monthly approach appeared more suitable for considering weather effects over microalgae culture

Considerable evidence supports the enhanced utilization of high-quality protein to obtain optimal health subsequences. Microalgae are a valorous source of proteins that can be employed as functional, nutritional, and remedial supplies. An effective microwave-assisted extraction method based on ionic liquids has been utilized in this study to extract proteins from microalgae Nannochloropsis oceanica biomass. The study of microwave-assisted extraction was carried out under varying conditions of temperature (30–80 °C), extraction time (5–35 min), and IL concentration (0–4.67% w/v). Among the six types of examined IL, choline acetate was an effective one for extracting total protein from microalgae biomass. The highest protein yield was obtained at 0.5 g microalgae, 2% w/v [Ch][Ac], and 40 °C for 30 min, representing 26.35% of protein yield and 65.06% of total protein extracted from the Nannochloropsis oceanica biomass. Meanwhile, conventional method of Soxhlet resulted in the protein yield of 0.63%. Only 1.56% of total Nannochloropsis oceanica protein was extracted by extraction method of Soxhlet which uses the hazardous solvent. The outcomes illustrated the superiority of [Ch][Ac]-based microwave-assisted extraction to conventional methods. This innovative procedure is recommended to have significant usage for the separation of proteins. The outcomes from this study would be beneficial in recognizing and harnessing significant microalgae biochemical from IL-based microwave-assisted extraction process to develop new and improved bioproduct technologies.

Microalgae contain a significant amount of carbohydrates that can be converted further to produce valuable compounds. To extract carbohydrates from microalgae, sub-critical water extraction (SWE) is a viable and novel method. Compared to other existing chemical and biological extraction methods, SWE is more economical, effective, and efficient in terms of process conditions. This process uses high temperature and pressure of water at just below supercritical conditions to keep water at a liquid state. This study aims to investigate the factors that affect the extraction yield of carbohydrates from microalgae Nannochloropsis sp. using the SWE process. The extraction was carried out at a temperature of 160 – 320 oC, a duration of 5 – 25 min, and microalgal biomass loading of 5 - 25% w/v. The kinetics study was conducted in an extraction time of 5 – 25 min at 200 oC and 5% (w/v) biomass loading. A simplified kinetic model based on a consecutive reaction was used to describe carbohydrate production and decomposition via SWE. It was found that the maximum yield of total carbohydrate was 18.04 g/100 g which was obtained at 200 oC, 10 min, and 5% (w/v) microalgal biomass loading. The carbohydrate concentration was decreased as the temperature, extraction time and microalgal biomass loading increased. This result indicated that the SWE is a promising extraction method for carbohydrate recovery from microalgae, and the factors investigated here had a significant effect on the extraction process. The proposed kinetic model was also able to capture the experimental data well within the range of operating conditions studied in this work.

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Biomass of algae is a very potent adsorbent for absorbing aqueous waste containing heavy metals and organic dyes. This study purposes to confirm the ability of adsorbents from green algae Nannochloropsis sp. modified with silica (ASN) and followed by coating magnetite particles (ASN-MPs) to absorb simultaneously the mixture of Methylene Blue (ME) and Cu(II) cations in aqueous solution. Simultaneous sorption of ME and Cu(II) cations to ASN and ASN-MPs was carried out by the batch method with the interaction pH condition 7, contact time 90 min, and initial concentrations of ME and Cu(II) cations (0.1–1.0 mM). Based on adsorption data, Cu(II) cations have a greater adsorption rate and capacity (qm) compared to ME at the same contact time and initial concentration. The adsorption capacity (qm) values of the bi-component ME and Cu(II) cation mixture in ASN and ASN-MPs were 1.39 × 10− 1 and 5.32 × 10− 1 mmol g− 1, respectively, with the binary Langmuir adsorption isotherm constant for Cu(II) cations greater than ME. Modified adsorbent from algae Nannochloropsis sp. with silica matrix and magnetite particle coating is an adsorbent that has a high effectiveness in the collective sorption of ME and Cu(II) cations. Therefore, these adsorbents can be used for the adsorption of cation mixtures of heavy metals and organic dyes that are cationic in solution.

This work proposes a way to maximize the potential of a Nannochloropsis sp. biorefinery process, through membrane technology, producing an extract enriched in soluble proteins, free from the insoluble protein fraction, with a low lipid content and eliminating the colored chlorophyll-a. This procedure, following the principles of a circular economy approach, allows for the valorization of a stream from the biorefining of Nannochloropsis sp. that, otherwise, would be considered a residue without commercial value. The process proposed minimizes fouling phenomena at the membrane surface, making it possible to achieve high permeate fluxes, thus reducing the need for membrane cleaning and, therefore, contributing to an extended membrane lifetime. Supernatant obtained after centrifugation of a suspension of ruptured Nannochloropsis sp. cells was processed by ultrafiltration using a membrane with a cut-off of 100 kDa MWCO. Two different operating approaches were evaluated—controlled transmembrane pressure and controlled permeate flux—under concentration and diafiltration modes. Ultrafiltration operated in a diafiltration mode, under controlled permeate flux conditions, led to the highest soluble protein recovery (78%) with the highest constant permeate flux (12 L·m−2·h−1) and low membrane fouling.

The effects of mono- and bi-microalgal diets on shell length, organic tissue, and survival of Spondylus limbatus juveniles were tested in two separate feeding experiments. The first examined nine single species of microalgae: Chaetoceros gracilis, C. muelleri, Isochrysis aff. galbana (T-ISO), Tetraselmis chuii, T. maculata, Pavlova lutheri, Dunaliella salina, Rhodomonas sp., and Nannochloropsis sp. An extra treatment maintaining the juveniles in a long line culture was at Ayangue Bay, Province of Santa Elena, Ecuador. Single diets of P. lutheri, C. muelleri, and C. gracilis showed the best combined growth of survival performance in juveniles, and were therefore selected for the bi-algal diet experiment design with the inclusion of I. galbana T-ISO due to its recommended use in bivalve culture. A second experiment consisted in selecting the best three microalgae species that resulted from the first experiment and combined each other in binary treatments at 1:1 ratio. All bi-algal diets in combination with P. lutheri showed good result in growth (shell and biomass), yield, and survival. However, single P. lutheri mono-algal diet showed equal or better performance index than the other bi-algal combined diets, demonstrating the pertinence in using this microalga as food for S. limbatus juveniles.

The increased concentration of Nannochloropsis sp. microalgae during the harvesting process is of great importance economically. Separation of Nannochloropsis sp. using Polyvinylidene Fluoride (PVDF) polymeric membrane was studied with the addition of 2% LiCl to improve up-concentration performance. The Hermia model is used to predict the type of fouling on the membrane. Cleaning with NaOCl 1000 ppm solution was carried out to overcome fouling on the membrane. PVDF/LiCl membranes were prepared using the immersion-precipitation phase inversion method. The results showed that the addition of LiCl caused an increase in membrane hydrophilicity as indicated by a decrease in the value of the contact angle from 94.8° to 70-84°. Membrane morphology changed from finger-like to sponge-like. The concentration of Nannochloropsis sp. increased from 563.92 to 5097.5 ppm. The membrane performance after cleaning is still very good because it produces recovery is more than 89.924%, and the microalgae rejection is 100%. It was concluded that the PVDF membrane after the addition of LiCl could improve the up-concentration performance of Nannochloropsis sp. and NaOCl solution was very effective in overcoming fouling on the membrane.

Powdered biomass of Nannochloropsis sp. and Tetraselmis sp. were used as innovative ingredients in wheat tortillas at flour substitution levels of 0.5–3.0%. Incorporation of microalgae into the tortilla formulations led to increased protein and fat content. The content of phenolic and carotenoids was also higher in microalgae-enriched tortillas, especially for those enriched in Nannochloropsis sp. at a flour substitution level of 3.0%. Not only the phenolic content but also the antioxidant capacity of the tortillas was higher after microalgae incorporation. Bioaccessible polyphenols were also higher in microalgae-containing tortillas as well as the antioxidant capacity of the enzymatic digestive extracts. No major differences in physical parameters (besides colour) were observed, and the overall acceptance of the microalgae-enriched tortillas assessed after a sensorial analysis was comparable to that of the wheat-only controls. Moreover, the purchase intention of the products as well as the acceptability index suggested that the tortillas would have a good acceptance. Several reports highlighted the nutritional value of microalgae. The production of microalgae and their utilisation as novel ingredients in innovative foods will increase the sustainability of the food industry and promote health. info:eu-repo/semantics/acceptedVersion

Lipidi izolirani iz biomase mikroalgi Nannochloropsis sp. predstavljeni su kao perspektivna sirovina za proizvodnju biodizela. U ovom radu proveden je fototrofni šaržni uzgoj s pritokom supstrata u otvorenom sustavu na izvornoj f/2 podlozi uz dodatak natrijevog bikarbonata te fototrofni šaržni uzgoj s pritokom supstrata u barbotirajućoj koloni na izvornoj f/2 podlozi bez dodatnog izvora ugljika. Tijekom uzgoja praćene su promjene udjela proteina, ugljikohidrata i lipida u izdvojenoj biomasi kao i sastav pigmenata te profil masnih kiselina u ukupnim lipidima. Utvrđeno je da u periodu smanjene koncentracije fosfora, metabolizam mikroalge se usmjerava prema akumulaciji lipida i ugljikohidrata kao rezervnih makromolekula uz smanjenje udjela proteina. Posljednjeg dana šaržnog uzgoja u otvorenom bazenu postignuta je koncentracija biomase od 0,515 g Lˉ¹, a maksimalna produktivnost biomase od 0,8796 mg Lˉ¹ hˉ¹ postignuta je osamnaestog dana uzgoja. Šaržnim uzgojem u barbotirajućoj koloni koncentracija biomase na kraju uzgoja iznosila je 0,458 g Lˉ¹, a produktivnost sinteze biomase tada je bila 0,8297 mg Lˉ¹ hˉ¹. Kemijska flokulacija sa željezovim (III) kloridom potvrđena je kao alternativna metoda za izdvajanje stanica mikroalgi. Naposljetku, u radu je predstavljen elaborat tehničko-tehnološkog rješenja postrojenja za proizvodnju biodizela. Lipids isolated from biomass of microalgae Nannochloropsis sp. are presented as a promising feedstock for biodiesel production. Cultivation methods used in this paper were phototrophic fed-batch cultivation with substrate inflow in an open pond system on the original f/2 medium with sodium bicarbonate and phototrophic fed-batch cultivation with substrate inflow on the original f/2 medium without supplementation of carbon source in a bubble column. Changes in the content of proteins, carbohydrates and lipids were monitored in the separated algae biomass during cultivation. The composition of pigments and the profile of fatty acids in total lipids were as well monitored simultaneously. During the period of reduced phosphorus concentration it was confirmed that metabolic responses of microalgae lead to the accumulation of lipids and carbohydrates as reserve macromolecules and to a decrease in protein content. On the last day of fed-batch cultivation in open pond, biomass concentration of 0,515 g Lˉ¹ was achieved. The maximum productivity of 0,8796 mg Lˉ¹hˉ¹ was achieved eighteenth day of cultivation. Additionally, on the last day of fed-batch cultivation in bubble column, biomass concentration was 0,458 g Lˉ¹ and productivity of biomass synthesis was 0,8297 mg Lˉ¹ hˉ¹. Chemical flocculation with iron (III) chloride has been confirmed as an alternative method for microalgae cell harvesting. Lastly, technical-technological solution for a biodiesel production facility was presented in this paper.

The microalgae Aurantiochytrium sp. (AUR), Isochrysis sp. (ISO), and Nannochloropsis sp (NAN) were studied as possible alternative feeds to well established commercial compound feeds for both rotifers (Brachionus plicatilis) and Artemia franciscana. Fatty acid (FA) composition —relative (in % of total FAs) and absolute (in mg/g dw)—was determined in order to assess their potential for providing essential FAs. The FA profiles showed relevant differences between the four feeds (compound feed and the three microalgal species), but less stark than in the feeds themselves. Whereas Isochrysis sp. was relatively rich in DHA and poor in EPA, 18.6 ± 1.7% vs 0.6 ± 0.0%, respectively, Nannochloropsis sp. had the opposite pattern, 0.2 ± 0.3% vs 28.3 ± 0.7%. Aurantiochytrium sp. was rich in DHA (19.1 ± 0.2% corresponding to 89.8 ± 0.2 mg/g dw), but posed difficulties as a feed for both rotifers and artemia, given its low lipid incorporation and, in particular, poor DHA deposition. Rotifers fed the compound feed had the best combination of n3 PUFA levels (22.1 ± 0.1 mg/g dw), DHA contents (13.6 ± 0.4 mg/g dw), and DHA/EPA ratios (~3), being rotifers fed AUR and ISO feeds second best. Hence, these microalgae may deserve to be further explored as potential sources of specific FAs in rotifers and artemia., Food science; Food technology; Biotechnology; Aurantiochytrium sp.; Isochrysis sp.; Nannochloropsis sp.; Lipid composition rotifers; Artemia franciscana.

Nannochloropsis sp. is a green alga that is widely used in the aquaculture industry as a feed in Malaysia, but genetic engineering studies of this alga are still underexplored even though there is a growing interest in microalgae genetic engineering for various industrial purposes. This study aims to investigate the efficiency of three transformation methods normally done on microalgae, namely polyethylene glycol (PEG), electroporation, and glass beads on Malaysian indigenous Nannochloropsis sp. using two commercially available plasmids, pUC19 and pGEM-T easy vector as well as an amplicon of ampicillin resistance (AMPR) gene. In this study, out of three transformation methods tested, positive transformants of Nannochloropsis sp. were successfully obtained via electroporation method. Further verification via polymerase chain reaction (PCR) and sequencing confirmed that the electroporation method was found to be the sole successful method in producing transgenic lines of our locally isolated Nannochloropsis sp. Results from this study proved the efficiency of electroporation for delivery of transgene to this green alga which has been reported to be tedious. The described method also provides the gateway for developing Nannochloropsis sp. as a delivery system to aquatic organism due to its importance in the industry., Graphical Abstract

Nannochloropsis sp. has received increased attention by researchers in recent years due to its complexity and abundance of lipid structures. The lipids of this microalgae species have been identified to contain large quantities of neutral lipids which are capable of producing raw materials for nutraceuticals, food additives and biofuels. The production of biodiesel has received the greatest attention as there is an increase in global demand for both more fuel and more environmentally sustainable methods to produce such resources. The greatest challenges facing industries to mass produce viable products from microalgae involve the degradation of the cell wall and extracting the fatty acid of interest due to high costs. Various studies have shown that the extraction lipids from the microalgae can greatly influence the overall fatty acid composition. Different extraction methods can re- sult in recovering higher quantities of either saturated fatty acids, monounsaturated fatty acids or polyunsatu- rated fatty acids. Biodiesel production requires higher quantities of saturated fatty acids and monosaturated fatty acids as increased quantities of polyunsaturated fatty acids result in oxidation which decreases the perfor- mance of the biodiesel. Whereas, polyunsaturated fatty acids are required in order to produce pharmaceuticals and food additives such as omega 3. This review will focus on how different in-situ extraction methods for lipid and fatty acid recovery, influence the fatty acid composition of various Nannochloropsis species (oculate, gaditana, salina and oceanica). The mechanical methods (microwave, ultrasonic and supercritical‑carbon dioxide) of extraction for Nannochloropsis sp. will be critically evaluated. The use of enzymes will also be addressed, for their ability to extract fatty acids in a more environmentally friendly manner. This paper will report on the viable byproducts which can be produced using different extraction methods.

Pharmaceuticals and their metabolites are released into the environment by domestic, hospital, and pharmaceutical industry wastewaters. Conventional wastewater treatment technology does not guarantee effluents of high quality, and apparently clean water may be loaded with pollutants. In this study, we assess the performance and efficiency of free and immobilised cells of microalgae Nannochloropsis sp. in removing four pharmaceuticals, chosen for their occurrence or persistence in the environment. These are paracetamol, ibuprofen, olanzapine and simvastatin. The results showed that free microalgae cells remain alive for a longer time than the immobilised ones, suggesting the inhibition of cell proliferation by the polymeric matrix polyvinyl alcohol. Both cells, free and immobilised, respond differently to each pharmaceutical. The removal of paracetamol and ibuprofen by Nannochloropsis sp., after 24 h of culture, was significantly higher in immobilised cells. Free cells removed a significantly higher concentration of olanzapine than immobilised ones, suggesting a higher affinity to this molecule than to paracetamol and ibuprofen. The results demonstrate the effectiveness of Nannochloropsis sp. free cells for removing olanzapine and Nannochloropsis sp. immobilised cells for removing paracetamol and ibuprofen.

The current study evaluated the effects of fish oil replacement with eicosapentaenoic acid-enriched single-cell microalgae in the diets of larval and postlarval kuruma shrimp. Experimental diets containing different level of Nannochloropsis sp. powder (10, 40, 70 g/kg) and lipids (2, 8, 10, 14, 35, 58 g/kg) were evaluated. The substitution of fish oil with algal powder significantly improved shrimp growth compared to that in the control group, with the highest final body weight recorded at 70 g/kg in larvae and 40 g/kg in postlarvae. Larvae fed algal lipids with a dry weight percentage in the diet of greater than 10 g/kg showed significantly lower performance than those in the control group. The neutral lipids in the tissue of the postlarvae that had been fed algal lipids had an improved fatty acid profile, as the content of highly unsaturated fatty acids increased compared to that in the other groups. The content of docosahexaenoic acid increased in the tissue, indicating the possible occurrence of the metabolism and accumulation of Nannochloropsis sp. essential fatty acids. Algal powder could replace FO up to 140 g/kg in shrimp diets without compromising growth and FA profiles.

Microwave assisted extraction derivatization (MAED) was investigated for preparing fatty acid methyl ester (FAME) derivatives to analyse the fatty acid (FA) composition of Nannochloropsis sp. algae. This method was compared against the conventional methods of oven assisted derivatization and direct derivatization without prior extraction. The derivatized FAMEs were analysed using GC-MS to identify and quantify the FAs present. Conventional methods have been carried out for years, but they are time consuming and require high temperatures and harmful chemicals. The MAED approach developed is 5 times (15 min) faster compared to the conventional and direct derivatization methods (75 min) optimised for FA analysis of Nannochloropsis sp. algae. The MAED method recovered significantly more FAs (51 wt%) from algal samples compared to conventional (42 wt%) and direct derivatization (34 wt%). Additionally it was shown that a sample extraction step is critical to improving the derivatization yield of algal samples for both oven assisted and MAED techniques. Fourteen FA components were identified in Nannochloropsis sp. algal samples and were evaluated for their potential use for biodiesel and biopharmaceutical products. The developed MAED method allows for a rapid, robust and accurate preparation of algal samples in order to determine their FA composition.

Microalgae are photosynthetic microorganisms widely used at the industrial level because of their high content of compounds with bioactive properties such as antimicrobial peptides. These compounds have a wide range of action mechanisms, do not produce the resistance of conventional antibiotics and could be effective against bacteria, fungi, viruses, parasites, and even tumor cells. In this work, by mechanical cell lysis treatment, a protein extract of dry biomass of Nannochloropsis sp was obtained, subsequently, it was hydrolyzed with an enzyme complex of proteases, papain, and pancreatin, for 6 hours, at 44 ° C and pH 7. Finally, the antimicrobial activity of the fraction of hydrolyzed extract with a size less than 3 kDa was evaluated against Staphylococcus aureus, Escherichia coli, and Candida albicans, obtaining a percentage of growth inhibition of 93.1%, 96.6%, and 14.4% respectively, which represents a peptic extract with bacteriostatic and fungistatic properties. Resumen Las microalgas son microorganismos fotosintéticos ampliamente utilizados a nivel industrial gracias a su alto contenido de compuestos con propiedades bioactivas como lo son los péptidos antimicrobianos. Estos compuestos son eficaces contra bacterias, hongos, virus, parásitos e incluso células tumorales, poseen una amplia variedad de mecanismos de acción y no generan la resistencia de los antibióticos convencionales. En este trabajo, a través de lisis celular mecánica, se obtuvo un extracto de proteínas a partir de biomasa seca de Nannochloropsis sp., posteriormente fue hidrolizado usando un complejo enzimático de proteasas, papaína y pancreatina, durante 6 horas, a 44°C y pH 7. Finalmente, se evaluó la actividad antimicrobiana de la fracción de extracto hidrolizado que poseía un tamaño menor a 3 kDa contra Staphylococcus aureus, Escherichia coli y Candida albicans, obteniendo un porcentaje de inhibición de crecimiento de los microorganismos de 93,1%, 96,6%, y 14,4% respectivamente, lo cual representa un extracto peptídico con propiedades bacteriostáticas y fungistáticas.

Harvesting, a challenging step of microalgae processing appears to be promising using flocculation method by the addition of tannin based natural biopolymer, AFlok-BP1. In this study, marine microalgae Nannochloropsis sp. was flocculated using AFlok-BP1 to evaluate its effectiveness in terms of flocculation efficiency, pH and dosages used, zeta potential, floc morphology characterization with comparison to the uses of aluminium sulphate and alkaline-induced pH. Oleaginous marine microalgae Nannochloropsis sp. was found to work effectively using AFlok-BP1 at an acidic pH 5 with more than 90% efficiency obtained at 160 mg/L. The finding was further supported with great instability of microalgae surface charge of -0.33 ± 0.27 mV, hence maximum destabilization of microalgae was believed to occur. The use of alum also effective to harvest Nannochloropsis sp. at neutral pH 7 with comparable efficiency as AFlok-BP1, but high dosage needed for more than 300 mg/L was at major concerns. Similarly, improved efficiency was observed for alkaline-induced pH for almost 100% efficiency. This would provide a better alternative for marine microalgae flocculation however, high concentration of minerals in the harvested biomass due to pH increase in need of further evaluation. To summarize, AFlok-BP1 would be a viable option to harvest marine microalgae Nannochloropsis sp. for the production of valuable compounds as it is an environmental friendly flocculant and provide no potential toxicity to the harvested biomass.

In this work, the co-pyrolysis and co-gasification of Nannochloropsis sp. microalgae (NM) and Colombian bituminous coal (CC) were performed in order to evaluate potential synergistic effects and the kinetic parameters, which are essential for advancing the co-utilization. The effect of the share of feedstock, microalgae and coal, on the co-pyrolysis and co-gasification behavior was studied under different heating rates and temperatures. There were synergistic effects between the two fuels during their co-pyrolysis process, especially for that mixture containing 50 wt% of microalgae. At conversion levels