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The failure of mass production of Spirulina plateaus can be attributed to an imbalance of nutrients (C:N) and an increase in accumulated sodium ions, coupled with the traditional harvesting process. The current study aims at the recovery of stressed and red cultures of Spirulina platensis as well as enhanced phycocyanin accumulation. The stressed Spirulina platensis cultures were obtained from a local Egyptian Spirulina production farms, which were further subjected to water analyses after removing the Spirulina biomass. Optimization was performed within 300-ml water path photobioreactor. Spirulina platensis samples were incubated with Zarrouk medium comparing with those modified using ammonium bicarbonate or ammonium acetate instead of sodium bicarbonate. Continuous batching was performed every 12 days during three sequenced batches. Growth measurements (dry weight and pigments) were performed along the incubation time. It was found that carbon content of the growth medium seems to be more effective in Spirulina growth and biomass characteristics. Under different carbon sources, acetate resulted in the maximum dry weight of 1.48 g·l -1 and recovery percentage of 463.3%. Such effect was extended along the different incubation batches. Various carbon concentrations revealed that moderate concentration of carbon in the form of acetate (0.699 g·l -1 ) leads to the maximum growth under the same nitrogen content. A similar trend was observed with chlorophyll and phycocyanin accumulation, while carotenoids showed the opposite manner., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This paper deals with the biological potential of coordination compounds based on binuclear core [Mo V 2 O 2 E 2 ] 2+ (E = O or S) coordinated with commercially available ligands such as oxalates (Ox 2- ), L-cysteine (L-cys 2- ), L-histidine (L-his - ), Iminodiacetate (IDA 2- ), Nitrilotriacetate (HNTA 2- or NTA 3- ) or ethylenediamine tetraacetate (EDTA 4- ) by means of various in vitro assays in a screening approach. Results suggest that the obtained complexes show weak antibacterial and antifungal properties while not being cytotoxic on cancerous and mammalian cells. In contrast, [Mo 2 O 2 E 2 (L-cys) 2 ] 2- complexes stand out as powerful antioxidant, whereas [Mo 2 O 2 E 2 associating tetraphenylphosphonium counter-cations display strong antibiotic activity. Finally, some complexes have evidenced a positive activity towards the growing of spirulina platensis together with a modification of the proportions of biological components inside the cells. These findings reveal promising bioactivity of the bridged binuclear Mo 2- associating tetraphenylphosphonium counter-cations display strong antibiotic activity. Finally, some complexes have evidenced a positive activity towards the growing of spirulina platensis together with a modification of the proportions of biological components inside the cells. These findings reveal promising bioactivity of the bridged binuclear Mo (+V) cores inside complexes and encourage further research for new highly active yet non-toxic molecules for biological and biomedical applications., (Copyright © 2021. Published by Elsevier Inc.)

The high content of bioactive compounds in the microalga Spirulina platensis has recently attracted attention from food and pharmaceutical industries. However, for its application an effective preservation technique must be developed. In this paper, we investigated the use of a non-conventional rotary dryer (with an inert bed) for drying the microalga Spirulina biomass and the effects of the operational conditions (air temperature, intermittent feeding interval, filling degree of inert particles, and rotation speed) on its bioactive compounds. The results indicated that this non-conventional drying system offers an effective alternative for expanding the use of this biomass in an adequate form. We identified the conditions in which the dried material had maintained satisfactory contents of phenolics (air temperature of 70 °C and intermittent feeding interval of 10 min), flavonoids (intermittent feeding interval of 17.4 min), and phycocyanin compounds (air temperature of 40 °C), which were near to those present in fresh microalga.

Aims and Background: Spirulina (Arthrospira) platensis (SP) microalgae were cultured in Zarrouk Medium (ZM), containing three nitrogen concentrations (N-limited, N-optimal and Nrich medium) in ten liter-photo-bioreactor (10 L PBR) for 15-days, in order to study changes in lipid compounds (total carotenoids and total lipids and their effect on fatty acid profile). Based on US patent, the yield of bioactive compounds (such as gamma-linolenic acid GLA, C18:3) extracted from microalgae biomass, mainly depends on the extraction processes (1). GLA has much attention with respect to its therapeutic properties such as its ability to decrease blood cholesterol levels., Methods: The impact of the addition of N in cultures of S. platensis in terms of growth, biomasses and induced lipid compounds (total carotenoids and total lipid contents and its fatty acid profile), as well as the Sonication (SON) and Microwave (MIC) process as aiding techniques for lipid extraction compared with a Cold Condition (COL), was examined. GC/MS method was used to determine the fatty acid profile of lipid extract of SP cultures., Results: In all S. platensis tested culture, the SP was growing successfully, with varying degrees. In N-rich media, the highest cell growth rate and biomass yield were obtained compared with that recorded in other cultures. Under an N-limited condition, SP had higher Total Carotenoids (TCAR, 45.54 mg/g dw) and total lipid contents (TL, 29.51%± 1.92 g/100g dw) compared with that recorded either in N-rich (11.2 mg/g dw) or in N-optimal (6.23 mg/g dw) cultures. Thus, SP copes with the N -stress by altering the metabolic pathways towards inducing lipid biosynthesis. To maximize the TL and TCAR extraction yields, from N-limited cultures, a set of operating process was applied including the Sonication (SON) and Microwave (MIC), which were used as aiding techniques for lipid extraction compared with the Cold Condition (COL) techniques. The results showed that the extraction efficiency of the S. platensis TL increased in the following order: MIC (29.51%± 1.92) > SON (25.46% ± 1.65> COL (20.43% ±1.43). In a comparative study for its fatty acid profiles (FAPs) among all SP cultures, lipids were analyzed by GC/MS. The predominant fatty acids (>10%, of total FA) were found to be myristic acid (C14:0, MA), palmitic acid (C16:0, PA) and oleic acid (C18:1)., Conclusion: The study concluded that the N-limited condition was found to have a strong influence on biomass dry weight and lipid contents and total carotenoids in SP cells compared to either Nrich or N-optimal conditions. The use of sonication and the microwave techniques lead to a great increase in the extraction of lipid contents and in high amount Polyunsaturated Fatty Acids (PUFAs) in N-limited cultures, in particular, the omega-6 (ω 6) and omega-3 (ω 3) of the essential C18 fatty acids. It seems that the SP rich in lipid content with a high amount of GLC produced under nitrogen limitation in PBR conditions can be used as a food additive or as a nutritional supplement., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Extraction of chlorophylls has received scant attention or priority over phycobiliproteins from Arthrospira platensis. In fact extraction of chlorophylls from spent biomass (left after extraction of phycobiliproteins which goes as waste or underutilized) on drying, will improve the economics of the overall downstream processing. Ethanol (yield 5.75 mg/g, db), being a food grade solvent, was preferred over acetone and dimethyl sulfoxide in spite of their slightly better yields (5.85 mg/g, db). The best conditions were 100% concentration of ethanol, 1:8 S/L ratio, pH 6, 50 °C temperature and 1 h extraction time. An increase of 125% in yield besides reduction of 83.3% in extraction time (from 6 to 1 h) could be achieved at standardized conditions. Low-Humidity drying was observed to be a possible alternative to freeze drying for drying of spent biomass. Ultrasonication as pre-treatment and ethanol as solvent were found effective for extraction of chlorophylls from dry spent biomass., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Aerobic composting is an effective way to dispose of organic waste. However, considerable carbon is converted into CO 2 and emitted into the atmosphere, which is a waste of the carbon resource and has the potential for the greenhouse gas effect. In this study, an innovative approach coupling aerobic composting exhaust and Spirulina platensis cultivation has been proposed and investigated, resulting in a double-edged solution to mitigating waste and co-generating biomass with a minimal cost of CO 2 supplied in the culture. Experimental results showed that the maximum biomass productivity ranged from 56.61 to 58.38 mg·L -1 ·day -1 was achieved using aerobic composting exhaust as a carbon source. Moreover, the CO 2 fixation rates of 46.36 mg·L -1 ·day -1 and 76.81 mg·L -1 ·day -1 were obtained by S. platensis cultivation. Finally, the chemical composition analysis of S. platensis biomass obtained in an optimum condition showed an abundance of proteins and lipids, thereby indicating its great potential for biofuel industry., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The study was performed to investigate the effects of using cow effluent for the cultivation of Spirulina platensis on its biomass production and cell physiology. S. platensis was cultivated in three different cow effluents (CE) used as cultivation medium during 15 days. CE was prepared using dry cow manures, and it was further modified with supplement of NaNO 3 (CEN) and NaNO 3  + NaCl (CENS). High nitrate value stimulated chlorophyll-a and total protein content of the cyanobacterium and also biomass production in standards medium (SM) and CEN media. Total carbohydrate content of S. platensis grown in CE media was found to be higher (p < 0.05) than that of SM. Productions of biomass and biochemical compounds by the cyanobacterium grown on the CE and SM media were evaluated by using multivariate approach. Conductivity, oxidation reduction potential (ORP), salinity, pH, and TDS played important role (p < 0.01) in the biochemical composition. As an effective explanatory factor, ORP had a significant positive correlation with H 2 O 2 , whereas negatively correlated with chlorophyll-α, biomass production, filament length, and proline. Canonical correspondence analysis proposed that biochemical compounds of S. platensis were not only affected by salinity and nutrition of media but also by pH and ORP. The present study indicated that CEN as a low cost model medium had high potential for the production of biomass by S. platensis with high protein content.

This study investigates the potential application of the polyethyleneimine- (PEI) and amidoxime-modified Spirulina (Arthrospira) platensis biomasses for the removal of uranium ion in batch mode using the native biomass as a control system. The uranium ion adsorption was also characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra, zeta potential analysis, and surface area measurement studies. The effects of pH, biomass amount, contact time, initial uranium ion concentration, and ionic strength were evaluated by using native and modified algal biomass preparations. The uranium ion removal was rapid, with more than 70% of total adsorption taking place in 40 min, and equilibrium was established within 60 min. From the experimental data, it was found that the amount of adsorption uranium ion on the algal preparations decreased in the following series: amidoxime-modified algal biomass > PEI-modified algal biomass > native algal biomass. Maximum adsorption capacities of amidoxime- and PEI-modified, and native algal biomasses were found to be 366.8, 279.5, and 194.6 mg/g, respectively, in batchwise studies. The adsorption rate of U(VI) ion by amidoxime-modified algal biomass was higher than those of the native and PEI-modified counterparts. The adsorption processes on all the algal biomass preparations followed by the Dubinin-Radushkevitch (D-R) and Temkin isotherms and pseudo-second-order kinetic models. The thermodynamic parameters were determined at four different temperatures (i.e., 15, 25, 35, and 45 °C) using the thermodynamics constant of the Temkin isotherm model. The ΔH° and ΔG° values of U(VI) ion adsorption on algal preparations show endothermic heat of adsorption; higher temperatures favor the process. The native and modified algal biomass preparations were regenerated using 10 mM HNO3. These results show that amidoxime-modified algal biomass can be a potential candidate for effective removal of U(VI) ion from aqueous solution.

For biomass production of Spirulina platensis as feedstock of fermentation, the culture characteristics of three typical mutants of 3-A10, 3-B2 and 4-B3 generated by atmospheric and room temperature plasmas (ARTP) mutagenesis were systematically studied by using CO2 aeration culture system and compared with the wild strain. The specific growth rate of wild strain in the pure air aeration culture system exhibited a 76.2% increase compared with static culture, while the specific growth rates of the 3-A10, 3-B2 and 4-B3 in pure air aeration culture system were increased by 114.4%, 95.9% and 88.2% compared with their static cultures. Compared with static culture, the carbohydrate contents of wild strain, 3-A10, 3-B2 and 4-B3 in pure air aeration culture system dropped plainly by 51.0%, 79.3%, 85.5% and 26.1%. Increase of CO2 concentration enhanced carbohydrate content and productivity. Based on the carbohydrate productivity, the optimal inlet of CO2 concentration in aeration culture was determined to be 12% (v/v). Under this condition, 3-B2 exhibited the highest carbohydrate content (30.7%), CO2 fixation rate (0.120gCO2·g(-1)·d(-1)) and higher growth rate (0.093 g L(-1)·d(-1)), while 3-A10 showed the highest growth rate (0.118 g L(-1)·d(-1)) and higher CO2 fixation rate (0.117gCO2·g(-1)·d(-1)) but low carbohydrate content (24.5%), and 4-B3 showed the highest chlorophyll (Chl) content (3.82 mg·g(-1)). The most outstanding mutant by static culture in terms of growth rate and carbohydrate productivity (3-B2), was also demonstrated by CO2 aeration culture system. This study revealed that the ARTP mutagenesis could generate the S. platensis mutants suitable for CO2 aeration culture aiming at biomass production., (Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.)

To improve cultivation efficiency for microalgae Spirulina platensis is related to increase its potential use as food source and as an effective alternative for CO2 fixation. The present work attempted to establish a technique, namely attached cultivation, for S. platensis. Laboratory experiments were made firstly to investigate optimal conditions on attached cultivation. The optimal conditions were found: 25 g m(-2) for initial inoculum density using electrostatic flocking cloth as substrata, light intensity lower than 200 μmol m(-2) s(-1), CO2 enriched air flow (0.5%) at a superficial aeration rate of 0.0056 m s(-1) in a NaHCO3-free Zarrouk medium. An outdoor attached cultivation bench-scale bioreactor was built and a 10d culture of S. platensis was carried out with daily harvesting. A high footprint areal biomass productivity of 60 g m(-2) d(-1) was obtained. The nutrition of S. platensis with attached cultivation is identical to that with conventional liquid cultivation., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

This paper presents a method to estimate the biomass of Spirulina cultivated on solid medium with sugarcane bagasse as a support, in view of the difficulty in determining biomass concentrations in bioprocesses, particularly those conducted in semi-solid or solid media. The genus Spirulina of the family Oscillatoriaceae comprises the group of multicellular filamentous cyanobacteria (blue-green microalgae). Spirulina is used as fish feed in aquaculture, as a food supplement, a source of vitamins, pigments, antioxidants and fatty acids. Therefore, its growth parameters are extremely important in studies of the development and optimization of bioprocesses. For studies of biomass growth, Spirulina platensis was cultured on solid medium using sugarcane bagasse as a support. The biomass thus produced was estimated by determining the protein content of the material grown during the process, based on the ratio of dry weight to protein content obtained in the surface growth experiments. The protein content of the biomass grown in Erlenmeyer flasks on surface medium was examined daily to check the influence of culture time on the protein content of the biomass. The biomass showed an average protein content of 42.2%. This methodology enabled the concentration of biomass adhering to the sugarcane bagasse to be estimated from the indirect measurement of the protein content associated with cell growth.

A 2 mm thin layer of wet Spirulina platensis biomass was dried using two methods: refractance window drying (RW) and combined RW and FIR drying (RWF). The effect of drying temperature (40–60 °C) and proximity to FIR heaters (5 and 10 cm) was evaluated on falling rate drying characteristics. The moisture (Deff) and thermal (α) diffusivity coefficients were obtained in the range 1.728 × 10−8 to 5.289 × 10−9 and 1.322 × 10−8 to 4.169 × 10−9 m2 s−1, respectively (R2, 0.921–0.984). RW drying at ≥50 °C caused loss of color, phytopigments, and lipid peroxidation. At 40 °C, RW drying led to a long drying period (300.50 ± 3.53 min), poor drying rate (0.039 ± 0.002 g-H2O/min), lowest Deff and α (5.289 × 10−9 and 4.169 × 10−9 m2 s−1), and chlorophyll loss (32.2%). Combined RW and FIR drying at 40 °C and 5 cm proximity (RWF40-5cm) reduced drying time (15.1%), increased drying rate (27.8%), improved α (15%), and Deff (14.9%). RWF40-5cm dried biomass showed excellent retention of color (ΔE = 4.64 ± 1.32), protein (93.8%), γ-linolenic acid (90.1%), chlorophyll (87.9%), and phycocyanin (86.7%) from freeze-dried biomass (FD). Low-temperature RWF40-5cm drying could be a potential alternative to freeze-drying for effective and safe drying of heat-sensitive Spirulina platensis biomass. [ABSTRACT FROM AUTHOR]

This study explores the cultivation of Spirulina platensis, a microalgae species, under various lighting conditions and pH levels to maximize biomass production. The organism primarily relies on light for autotrophic growth, and both light intensity and quality shape its cell growth and biomass composition. The investigation assessed the impact of different light-emitting diodes on Spirulina's dry biomass yield. A central composite design (CCD) and response surface methodology (RSM) were implemented for experimental design and optimization of cultivation procedures, examining light duration (7–14 h) and pH values (7–10). Optimum biomass yield was achieved under 14 h of light exposure at a pH level of 8.5, with dry biomass also peaking at these conditions. A verification test corroborated the predictive accuracy of these findings. The highest average dry cell weight, 2.07 ± 0.12 g/L, was attained under white light-emitting diode, followed by 1.95 ± 0.23 g/L under red light. This research sheds significant light on optimal conditions for S. platensis cultivation, demonstrating how the species responds to different light sources and pH levels, thereby providing valuable insights for enhancing biomass production. [ABSTRACT FROM AUTHOR]

In this work, we evaluated the protective capacity of Spirulina platensis biomass in preserving Lactobacillus delbrueckii subsp. bulgaricus WDCM 00102. The L. bulgaricus strain was freeze-dried in the presence of S. platensis biomass and the freeze-dried samples were then stored at 5 and 25EC for varying periods. Subsequently, the samples were rehydrated and bacterial plate counts were determined. The results indicate that a concentration of 12% S. platensis biomass was highly effective in preserving L. bulgaricus. Commercial products with higher S. platensis biomass content exhibited greater protective capacity. While S. platensis biomass is well-known for its prebiotic properties, its protective role has not been previously reported or thoroughly explored. This study demonstrates the protective capacity of S. platensis biomass in preserving L. bulgaricus, a strain particularly sensitive to preservation processes. [ABSTRACT FROM AUTHOR]

Light plays an important role in the photosynthesis and metabolic process of microalgae. However, how different light conditions regulate the biomass production and protein accumulation of microalgae is mostly unknown. In this study, the influence of different light conditions, including light colors, densities, and light:dark cycles on the cell growth and biochemical composition of Spirulina platensis was symmetrically characterized. Under different colored lights, S. platensis all shows an increase trend within the increased light intensity ranges; however, each showing different optimal light intensities. At the same light intensity, different colored lights show different growth rate of S. platensis following the sequence of red>white>green>yellow>blue. The maximum growth rate and protein accumulation were determined as 21.88 and 5.10 mg/(L·d) when illuminated under red LED. The energy efficiency of different light sources was calculated and ranked as red>white>blue≈green>yellow. Transcriptomic analysis suggests that red light can promote cell growth and protein accumulation by up-regulating genes related to photosynthesis, carbon fixation, and C-N metabolism pathways. This study provides a conducive and efficient way to promote biomass production and protein accumulation of S. platensis by regulating light conditions. [ABSTRACT FROM AUTHOR]

Spirulina platensis is an important source of pharmaceutically active metabolites. It is important to enhance and enrich the biomass of S. platensis cultures. Silver nanoparticles (AgNPs) have been used in many areas of biotechnology and biologically-synthetized silver nanoparticles (bio-AgNPs) have more beneficial effects on biosystems than chemically-synthetized AgNPs. In our study, Syzygium aromaticum-derived bio-AgNPs were added to S. platensis batch culture at 0–25 mg/L concentrations and the responses were evaluated. The highest optical densities and dry weight were detected at 5 mg/L bio-AgNP concentration, whereas 15 mg/L bio-AgNP triggered the highest fresh weight. Total phenolic, flavonoid and antioxidant capacities were also detected at their highest values between 1 and 15 mg/L bio-AgNP concentrations. The results revealed that bio-AgNP concentrations can be optimized and used as elicitors in order to enhance the growth and improved the biochemical composition. [ABSTRACT FROM AUTHOR]

In the last few decades, the recovery of high-added value compounds with high food potential using microalgae as feedstock has been one of the main challenges for both research and industry. This study provides a simple, affordable, and cost-saving approach for the selective recovery of C-phycocyanin (C-PC), chlorophyll a and carotenoids from Spirulina platensis biomass by using biocompatible and industrially approved solvents (such as CaCl2 and ethanol). The concentration and yield of each pigment in the liquid extract have been spectrophotometrically detected, whereas the decolorized protein-rich biomass has been analyzed by CIELab parameters. The most concentrated (566.4 μg/mL) and food-grade C-PC extract (purity index 0.7) was obtained by applying a biomass/solvent ratio (1:10) for the first round of extraction (20 min), followed by a second round at 1:5 using CaCl2 1.5% (w/v) aqueous solution. Additionally, the same trial enabled the production of the brightest decolorized protein-rich biomass (L* = 46.2), characterized by a yellow-orange tonality (h° values = 81.3°). Highlights: Natural pigments from Spirulina platensis biomass have been separately extracted Food grade high-purity C-phycocyanin has been recovered by CaCl2 1.5% w/v solution Chlorophyll a and carotenoids have been subsequently extracted by ethanol The colorimetric properties of spent decolorized biomass have been characterized [ABSTRACT FROM AUTHOR]

Spirulina platensis has roles in biotechnological product advancement due to its safety for humans and animals. Analysis of S. platensis extract by high-performance liquid chromatography reflected the presence of 14 phenolic and flavonoid compounds with different concentrations such as ellagic acid (333 µg/g), gallic acid (294 µg/g), methyl gallate (147 µg/g), naringenin (144 µg/g), and chlorogenic acid (142 µg/g). The isolated Aspergillus flavus from silage of maize was tested to evaluate the effect of S. platensis extract on aflatoxins B1, B2, G1, and G2 production. The treated silage with S. platensis extract showed the presence of 37±0.33 ppb, 0.59±0.16 ppb, 0.26±0.22 ppb, and 0.21±0.18 ppb compared to un-treated silage that showed 3.14±0.15 ppb, 0.81±0.08 ppb, 0.46±0.05 ppb, and 0.26±0.23 ppb aflatoxins of B1, B2, G1, and G2. These results were shown on the 10th day of incubation. On the 15th day of incubation, the treated silage showed less mycotoxins than un-treated silage. At different incubation periods, glucosamine was estimated as a growth development biomarker. The content of glucosamine was inhibited as a result of the effect of S. platensis extract on fungus growth with 53.71%, 49.19%, 47.84%, 38.47%, and 35.72% inhibition on the 3rd, 6th, 9th, 12th, and 15th day. [ABSTRACT FROM AUTHOR]

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The production and release of nanoparticles and their impacts on living organisms are among the most important concerns in the world. Spirulina platensis was chosen because of its ability to absorb more elements than other algae. Therefore, an experiment was conducted to improve the product quality of spirulina exposed to new type of nanoparticles. In this experiment, vanadium oxide nanoparticles (VNPs) and tungsten oxide nanoparticles (WNPs) were used at concentrations of 0, 0.001, 0.017, and 0.05 g/l. The measured indices such as protein percentage and concentrations of phycobiliproteins and carbohydrates were the most important parameters of spirulina. Results showed that the concentration of 0.001 g/l of VNPs significantly affected the amounts of protein and phycocyanin. It has also been observed that 0.001 g/l of WNPs significantly influenced the amounts of protein (5.3%) and phycocyanin (90%); however, WNPs at all concentrations increased the concentrations of protein and phycocyanin. A concentration of 0.05 g/l of WNPs increased phycocyanin content by 83% over the control. The examination of nanoparticles by spirulina showed that VNPs were more adsorbed by spirulina than WNPs. In general, VNPs were toxic to algae at concentrations of 0.017 and 0.05 g/l, but WNPs did not show any fatal toxicity. [ABSTRACT FROM AUTHOR]

Spirulina platensis has attracted special attention in various industries due to its natural pigments with specific performance characteristics. In this study, the effects of vitamin B12 (0.5 to 1.5 μg/l), date waste extract as a carbon source (1 to 1.5 g/l of glucose), and urea as a source of nitrogen (50 to 150 mg / l) parameters by fed-batch feeding under submerged culture was optimized and the production of Spirulina platensis and natural pigments were examined. The results showed that the addition of urea and date waste extract increased the production of biomass and phycocyanin, allophycocyanin, carotenoids, and chlorophyll. The results of the effect of vitamin B12 showed that this vitamin in low concentration has a positive effect on the production of spirulina and the pigments phycocyanin, allophycocyanin, carotenoids, and chlorophyll. Also, the use of date waste extract with vitamin B12 should be used optimally in combination with each other to achieve the highest production efficiency of biomass and pigments phycocyanin, allophycocyanin, carotenoids, and chlorophyll. At low concentrations of vitamin B12, increasing changes in date waste increase carotenoid production. Also, in low concentrations of date waste, with increasing changes in vitamin B12, carotenoid production increases, but in the highest concentration of these two variables, carotenoid production decreases due to the opposite effect. In high concentrations of vitamin B12, increasing changes in urea increase chlorophyll production. At the optimized condition, (Vitamin B12 0.5 µG.l-1, Date Waste Extract 1.5 G.l-1 Of Glucose, Urea 150 Mg.l-1) the Biomass, Phycocyanin, Allophycocyanin, Carotenoids And Chlorophyll Contents Were 203 (G/100g) 128, 8.42, 4.09 And 7.2 (mg.l-1). It Can Be Concluded That Vitamin B12 Along With The Use Of Date Waste Creates Mixotrophic Conditions In The Growth Of Spirulina Platensis, Which Leads To Increased Production Of Biomass And Natural Pigments. [ABSTRACT FROM AUTHOR]

Spirulina platensis (SP) has a high impact on multidiscipline usage worldwide. Vitamins are considered as growth promoters due to their metabolic bio-regulating roles. This study was conducted to investigate the effect of vitamins: riboflavin (B2), thiamine (B1), and ascorbic acid (C) on SP growth and contents of pigments, phenols, and phytochemicals besides its antioxidant activities. Vitamins were added in different concentrations to Zarrouk’s medium and tested for their effects weekly for three weeks of spirulina cultivation. The results revealed that 25 mg·L−1 thiamine or riboflavin promoted the most significant contents of chlorophyll and carotenoids, respectively, after 14 days of cultivation. However, adding 10 mg·L−1 thiamine achieved the most significant increase in algal biomass yield and contents of chlorophyll, carotenoids phycocyanin, allophycocyanin, phycoerythrin, and phycobiliprotein after 21 days of cultivation. Qualitative analysis showed that both SP and SP supplemented with 10 mg·L−1 thiamine (SPt) for 21 days contain tannins and flavonoids but quantitative analysis approved that SPt recorded significant increase in phenolic and tannin contents. Moreover, SPt induced a significant increase of total antioxidant activity in vitro 1,1-diphenyl-1,2-picrylhydrazyl assay in comparison with SP. Vitamins especially thiamine added during SP culture could improve SP biomasses, pigments, and phytochemical contents and hence increased antioxidant capacity.

Recent escalating concerns surrounding textile wastewater pollution and the urgent need for sustainable treatment solutions to mitigate its environmental impact. This study investigates the multifaceted effects of Spirulina platensis (SP) cultivation in textile wastewater from two different sources (TWW1 and TWW2), focusing on growth kinetics, Chemical Oxygen Demand (COD), and nutrient removal percentage, and seed germination enhancement. Results showed that SP exhibited comparable growth performance in TWW1 and TWW2 to the control, indicating its potential for sustainable wastewater treatment. Moreover, maximum COD removal percentages were achieved, reaching 62.59 ± 1.88 % for TWW1 and 46.68 ± 1.40 % for TWW2 on day 5. The COD removal process aligns best with the first-order kinetic model. Nutrient removal rates showed decreasing trends over time, with maximum phosphate removal percentages of 36.42 ± 0.73 % for TWW1 and 62.18 ± 1.24 % for TWW2, and maximum ammonia removal percentages of 59.34 ± 1.18 % for TWW1 and 69.31 ± 1.39 % for TWW2. FTIR analysis confirmed pollutant removal-induced changes in algal biomass functional groups. Seed germination studies indicated enhanced shoot and root development of vigna radiatas using treated TWW1 and TWW2 compared to the control, suggesting potential applications for irrigation. An increase in the lipid & carbohydrate content post-treatment was observed and it would be suitable for biofuel production. This comprehensive assessment demonstrates the synergistic benefits of phycoremediation in simultaneously removing pollutants, promoting plant growth, and enhancing wastewater treatment efficiency, underscoring its potential for sustainable water management practices. [Display omitted] • Textile wastewater is a good nutrient-rich source for the active growth of SP. • SP effectively removes pollutants from TWW within a shorter, sustainable timeframe. • Higher nutrient removal rate correlates with maximum COD removal on day 5. • COD removal by Phycoremediation aligns best with the first-order kinetic model. • Phycoremediated TWW improves seed germination by supplementing nutrients. [ABSTRACT FROM AUTHOR]

Rare earth elements such as neodymium (Nd) are important elements used mainly in developing new technologies. Although they are found in low concentrations in nature, they can be obtained by extracting solid samples such as phosphogypsum. Among the techniques, adsorption has been used successfully with several adsorbent materials. In this work, two strains of Spirulina platensis (LEB-18 and LEB-52) were employed as biosorbents for efficiently removing the Nd element from the aqueous media. Biosorption tests were carried out in a batch system, and the results of the biosorption kinetics showed that for both materials, the biosorption of Nd was better described by the Avrami model. Moreover, it could be considered that 80 min would be necessary to attain the equilibrium of Nd(III) using both biosorbents. The result of the biosorption isotherms showed that for both strains, the best-fitted model was the Liu model, having a maximum biosorption capacity of 72.5 mg g−1 for LEB-18 and 48.2 mg g−1 for LEB-52 at a temperature of 298 K. Thermodynamics of adsorption showed that for both LEB-18 and LEB-52 the process was favorable (∆G° < 0) and exothermic (∆H° −23.2 for LEB-18 and ∆H° −19.9 for LEB-52). Finally, both strains were suitable to uptake Nd, and the better result of LEB-18 could be attributed to the high amount of P and S groups in this biomass. Based on the results, a mechanism of electrostatic attraction of Nd3+ and phosphate and sulfate groups of both strains of Spirulina platensis was proposed. [ABSTRACT FROM AUTHOR]

Despite many advantages of third-generation biofuels, there are still numerous opportunities to improve their production efficiency and streamline their commercialization. The unpredictability of cultivating biomass is a major challenge to consistent, efficient production. In particular, the cultivation of Spirulina platensis biomass for biofuel production is affected by various environmental factors such as light, temperature, pH and the nutrient concentration of water. Since controlling these factors is energy intensive, a biomass prediction model would be helpful in anticipating biomass production and in indicating necessary adjustments to the process to improve yield. In this case, earlier is clearly better. This study developed a machine learning-based early prediction model, which identifies the earliest time during cultivation that the process parameters such as optical density and pH can accurately be used to predict biomass yield. In the case study, the early prediction model predicted the final biomass yield (on the 23rd day) by the 8th day of cultivation using ridge regression. Furthermore, an application of this model in pH control led to a 54.1% average improvement in biomass yield. This model may be used to monitor cultivation batches allowing problems (i.e. low yield) to be identified early. It can also be applied in process simulation and optimization to improve biomass yield. In summary, mathematical modelling can make the unpredictable biomass process more predictable and improve production efficiency. [ABSTRACT FROM AUTHOR]

Algal biomass from Spirulina platensis has been tested for the adsorption of chromium (VI) in aqueous effluents. The study was conducted using a central composite experimental design. The selected variables were: biomass (0.25–0.75 mg), initial chromium concentration (100–500 mg/L), and contact time (3–8 h). This study proved that spirulina biomass shows good adsorption capacity in the experimental space selected for the central composite experimental design (CCD). The maximum adsorption capacity was 40 mg Cr/g of biomass in the tests with 500 mg/L of Cr(VI) and 0.25 g of spirulina. The statistical analysis confirmed that the adsorption capacity can be modelled using a linear equation that only depends on the initial chromium concentration and the biomass dose. These results suggest that the adsorption of Cr in spirulina raw biomass can be considered in the development of large-scale applications. [ABSTRACT FROM AUTHOR]

As a counter to climate change, energy crises, and global warming, microalgal biomass has gained a lot of interest as a sustainable and environmentally favorable biofuel feedstock. Microalgal carbohydrate is considered one of the promising feedstocks for biofuel produced via the bioconversion route under a biorefinery system. However, the present culture technique, which uses a commercial medium, has poor biomass and carbohydrate productivity, creating a bottleneck for long-term microalgal-carbohydrate-based biofuel generation. This current investigation aims toward the simultaneous increase in biomass and carbohydrate accumulation of Spirulina platensis by formulating an optimal growth condition under different concentrations of nitrogen and phosphorous in flasks and a bubble photobioreactor. For this purpose, the lack of nitrogen (NaNO3) and phosphorous (K2HPO4) in the culture medium resulted in an enhanced Spirulina platensis biomass and total carbohydrate 0.93 ± 0.00 g/L and 74.44% (w/w), respectively. This research is a significant step in defining culture conditions that might be used to tune the carbohydrate content of Spirulina. [ABSTRACT FROM AUTHOR]

Spirulina platensis is a cyanobacterium with biological activities. This characteristic is mainly due to its blue pigment C-phycocyanin (C-PC), which is an important commercially available blue food colorant. To take maximum advantage of the benefits of C-PC, a comparative study of four different pretreatment techniques, namely, freeze–thaw (F/T), enzymatic (EE), ultrasound (US), and pulsed electric field (PEF) pretreatment, for C-PC extraction from S. platensis dry biomass was performed to select the method providing the highest yield and desired purity. The extraction of C-PC was conducted using 100 mM phosphate buffer, pH 6.8, which is a green solvent. The highest C-PC yield of 129.5 ± 7.78 mg/g was obtained with US pretreatment after 30 min of sonication at 40 kHz frequency. The next highest yield of 84.00 ± 2.13 mg/g was recorded after 240 μs of PEF pretreatment with a voltage of V = 24 kV/cm and 44 pulses (average pulse width of 5.36 μs). The highest purity of 2.47 ± 0.21 was obtained with F/T pretreatment, followed by US (2.15 ± 0.12) and PEF (2.13 ± 0.39). [ABSTRACT FROM AUTHOR]

Spirulina (Arthrospira platensis) is a microscopic filamentous cyanobacterium with a long history of basic and complementary alimentation. Nevertheless, a growing interest in its use in agriculture as biofertilizers and plant growth biostimulants was showed in the last years. Spirulina is commercially produced in large outdoor ponds under controlled conditions that affect both growth and biomass composition. Here, we have studied the influence of culture conditions on Spirulina growth (biomass production) and characterize the produced biomass for possible use in biopharming. The study of the effect of culture media, as well as temperature on growth and biomass composition, showed an optimal growth in temperatures at 30 and 35 °C with no difference between both tested media. The analysis of NPK content of produced biomass revealed that it contains the following: 10.9% N, 0.94% P, and 1.1 % K. In optimal growth conditions, the total biomass protein content varied from 64 to 71 %. Spirulina cells were harvested in all growth phases and analyzed for total polysaccharides (PS) in batch and continuous culture. The maximum PS production was observed during the exponential growth phase (1.5%). It was also found that the cultivation of Spirulina platensis in continuous culture increased its polysaccharide level (4.98%) compared to batch cultures. [ABSTRACT FROM AUTHOR]

Eco-friendly methods for extraction of phycocyanins (C-PC and A-PC) from dry biomass of Spirulina platensis were carried out employing nanoparticles (NP), polyethylene glycol (PEG) and salts. There are practically no reports on such methods of extraction of phyco- cyanins from S. platensis. Standardization of process parameters such as concentration of NP/salt/PEG, extraction time, temperature and solvent was carried out for all the methods employed to achieve maximum productivity (yield and purity). The standardized conditions for NP, salt and PEG based extractions were observed to be 10 p.g/mL, 3 mg/mL and 10% w/w concentration, respectively, phosphate buffer as an extraction solvent, 160 min of extraction time and 35 C of extraction temperature. Silver nanoparticles based extraction resulted in the highest yield (47.68 and 34.18 mg/g db) and purity (0.98 and 0.33) of C-PC and A-PC, respectively. These results are among the highest reported in the primary extraction (itself) without any additional field intervention or process aids. [ABSTRACT FROM AUTHOR]

Nitrogen is known to have a strong influence on the metabolism of lipids and protein in various microalgae. In the present study, the production of S. platensis was optimized in terms of biomass and protein by using different Nitrogen sources as NH4Cl, NH4NO3 and Urea. S. platensis was grown in Zarrouk’s medium in a 3000 ml Erlenmeyer flask, in which the NaNO3 was replaced by NH4Cl, NH4NO3 and Urea with concentrations of 0.010, 0.025 and 0.050 M. Cultures were incubated at temperature of 30oC, salinity of 25 ppt and initial pH of 9.5 under 12/12 hour light-dark photo period with normal white light. The results clearly showed that S. platensis successfully cultivated by using different Nitrogen regimes, and though the maximum biomass was produced in medium containing NH4NO3, but there is not significant differences between treatments (p>0.05). The maximum protein content was obtained in culture containing NH4NO3 followed by NH4Cl and KNO3, and there is not significant differences between treatments (p>0.05). Moreover, in all S. platensis cultures, increasing in nitrogen concentrations, led to an increase in maximum biomass and protein content. The chl. a content increased with increasing Nitrogen concentrations in all treatments and relatively high values (9.18 µg/ml) were found with KNO3 as a Nitrogen source at 14th day of culturing period. Overall, though the results of present studyclearly showed no significant differences between treatments, but using of NH4NO3 could have relatively more effectiveness than the other Nitrogen sources.

Over the last years, the cyanobacteria Spirulina platensis (SP) has attracted special attention, as it possesses remarkable antioxidant activity and high amounts of bioactive compounds, such as phycocyanin, carotenoids and phenolics. Since Spirulina platensis biomass shows extremely high moisture content, dehydration is a crucial treatment step, which ensures the prolonged shelf life of the final product. However, drying affects drastically the qualitative characteristics of heat-sensitive foodstuffs with high nutritional value, such as SP. In this study, four different drying techniques, atmospheric drying (AD), freeze drying (FD), vacuum drying (VD) and accelerated solar drying (ASD), were examined and compared considering crucial parameters, i.e., moisture content reduction, change of structure, colour deterioration, pigment content and antioxidant activity. As shown from the obtained results, vacuum drying achieves faster moisture lowering and higher carotenoid content equal to 0.58 + 0.01 mg (g dry solids)−1. On the other hand, atmospheric drying is efficient in preserving phycocyanin since its content was found equal to 9.65 + 0.19%dry weight, but in general cannot be industrially applied due to the long dehydration time. Finally, accelerated solar dried biomass showed the highest antioxidant activity (31.28 ±0.90% dry weight) mainly due to the degradation products after heating at high temperatures and stress conditions. [ABSTRACT FROM AUTHOR]

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Microalgae and cyanobacteria can be used as a potential biomass to produce hydrogen from stored glycogen and starch through fermentation and photofermentation. In this study, the potential of algal biomass i.e. Spirulina platensis hydrolysate as a substrate for sequential fermentative (I-stage) and photo-fermentative (II-stage) biohydrogen production was evaluated. Response Surface Methodology (RSM) was employed to find the optimum photofermentation conditions. From the preliminary optimization experiments, it was found that the significantly affecting factors for H 2 production were pH, dilution fold (D.F.) of fermentate and Fe(II) sulfate concentration during photofermentation (second stage). In the present study, 1% (w/v) Spirulina platensis hydrolyzate produced 23.06 ± 3.63 mmol of H 2 with yield of 1.92 ± 0.20 mmol H 2 /g COD reduced. In the second stage experiment 1510 ± 35 mL/l hydrogen was produced using inoculum volume-20.0% (v/v) and inoculum age-48 h of co-culture of Rhodobacter sphaeroides NMBL-01 and Bacillus firmus NMBL-03 under conditions pH-5.95, D.F. of dark fermentate-20.30 folds, Fe(II) sulfate concentration-0.412 μM, temperature-32±2 °C and light intensity-2.5 klux. • The S. platensis hydrolysate for two stage hydrogen production have been reported. • The bioprocess has been optimized for second stage photofermentation. • The optimized photo-fermentation factors are pH-5.95, D.F.-20.30 folds, Fe(II) sulfate-0.412 μM. [ABSTRACT FROM AUTHOR]

This study developed a rapid and non-destructive analytical method for biochemical analysis of the Spirulina biomass via FTIR spectroscopy and PLS regression. It was then used to monitor the biochemical changes in the biomass during an 8-day cultivation period in a 3-L internally-illuminated concentric-tube airlift photobioreactor at different light intensities (69, 110, and 166 µmol photons m-2 s-1). It was found that PLSregression have better predictive power than multipoint regression. It also yielded statistically similar results with conventional biochemical methods. This new method reduced the time for sample preparation and eliminated the extraction of target biomolecule for analysis. It was also found to be valuable in monitoring the changes in the total protein, carbohydrate and lipid content (% w/w of total biomolecules) in Spirulina biomass during its growth. It was observed that the protein content of the biomass decreased initially, which was compensated by an increase in the carbohydrate content. This may imply that biomass production may be driven by production of more carbohydrates during the early period of growth. Protein content then started to increase until the third day of growth and remained constant thereafter. Carbohydrate and lipid content also remained constant from the third day of growth. The lowest light intensity was found to have the highest protein content (60.4± 0.87 %w/w) but it has the lowest overall biomass productivity (0.090 ± 0.017 g L-1 d-1). While at the highest light intensity, protein content was slightly lower (57.3 ± 0.777 %w/w) than that of the lowest light intensity. But it has the highest overall biomass productivity (0.141 ±0.007 g L-1 d-1). [ABSTRACT FROM AUTHOR]

This paper describes the use of a linear programming method to construct a formula for preparing culture medium for Spirulina platensis (S. platensis) algae using Vinh Hao natural mineral water (Binh Thuan Province, Vietnam) with a low cost. The results show that the cost of preparing the culture medium using Vinh Hao mineral water is less than 252.49 VND/L, which is approximately 13.05 % less than the cost of Zarrouk medium. To verify the optimised medium composition, S. platensis algae was cultured in the two media under the same conditions (25 to 40 °C; pH 8.5 to 10.2). The algae biomass concentration reached 1.0 g/L after 7 d of culturing. The experimental growth rates of S. platensis algae in Vinh Hao culture medium and Zarrouk medium had an average difference of 1.49 %. This study provides a basis for implementing S. platensis algae production on an industrial scale using media formed from Vinh Hao natural mineral water from Binh Thuan Province, Vietnam. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of the inclusion of microbial biomass on the oxidative rancidity of tilapia rations storedfor 12 months. Treatments included a control diet and diets supplemented with either 0.01% vitamin E, 0.25 and 0.5% of Saccharomyces cerevisiae and 0.25 and 0.5% of Spirulina platensis. Experimental diets were stored in the dark inside plastic bags at room temperature (25 °C) for 12 months. The oxidative rancidity was measured as thiobarbituric acid reactive substances (TBARS). It was concluded that the inclusions of Spirulina platensis at 0.25% (1.734 ± 0.206) and 0.5% (1.629 ± 0.181) and Saccharomyces cerevisiae at 0.5% (1.459 ± 0.305) minimized the oxidative rancidity in comparation to control diet (2.843 ± 0.109) of Nile tilapia until 12 months of storage. [ABSTRACT FROM AUTHOR]

There is wide consensus that Spirulina can serve as a tool for wastewater management and simultaneously provide feedstock for biorefining. However, the economic aspects associated with its use remain a significant challenge. Spirulina cultivated in wastewater decreased the concentrations of both ammonia and nitrate and also served as a biodiesel source. The oil obtained in the feedstock was subjected to transesterification and turned into biodiesel. The biodiesel was subsequently analyzed in a test motor (water-cooled, four-stroke, single-cylinder compression ignition with injection). The tests were conducted at a constant 1500 rpm, and the output power was 3.7 kW. Mixtures of diesel and biodiesel were also enriched with carbon nanotubes (CNTs). The amount of CNTs added to the diesel was 30 mg L−1. The algae and de-oiled biomass were characterized using XRD analysis, and an ultrasonicator was used to mix the CNTs with diesel and spirulina blends. A series of tests were conducted at different load conditions (25%, 50%, 75%, and 100%) for all fuel blends. Test results were compared with a neat diesel engine with a CR of 17.5:1. Among the fuel blends, the B25 reported improved brake thermal efficiency and reduced emissions. The outcomes are a reduction in thermal efficiency of 0.98% and exhaust gas temperature of 1.7%. The addition of Spirulina biodiesel blends had a positive impact on the reduction of greenhouse gas emissions, including reductions of 16.3%, 3.6%, 6.8%, and 12.35% of CO, NOx, and smoke, respectively. The specific fuel consumption and CO2 emissions were reduced by 5.2% and 2.8%, respectively, for B25 fuel blends compared to plain diesel and B50. Concerning cost competitiveness, vigorous research on microalgae for the production of biodiesel can cut production costs in the future.

Summary: Hydrothermal liquefaction of microalgae under alkaline and acidic conditions has been widely investigated. However, limited data are available on the mechanism of aqueous phase formation during liquefaction. In the present work, we conducted a detailed characterization of the aqueous phase from hydrothermal liquefaction of Spirulina platensis using acetic acid and potassium hydroxide as the catalyst. GC‐MS analysis revealed that a large proportion of nitrogen‐based heteroatom compounds and few oxygen‐based heterocycle compounds were presented in all the aqueous phase. All the aqueous phase displayed alkalescence and a high level of total organic carbon. Whereas, the addition of potassium hydroxide reduced the total organic carbon and the average molecular weight of the aqueous phase. The conventional liquefaction converted the Spirulina platensis to plenty of water‐soluble amides, while these compounds were apt to form acids under both the alkaline and acidic catalysts. Based on the analyses, the general reaction frameworks for the catalytic liquefaction were also proposed. [ABSTRACT FROM AUTHOR]

Spirulina (Arthrospira) platensis a filamentous multi cellular cyanobacterium utilized as animal feed and human food supplement. This cyanobacterium is also a rich source of value-added pigments with diverse applications in the food industry, pharmaceuticals and molecular biology. This report describes a procedure for enhancement of the yield of valueadded pigment; c-phycocyanin (CPC) through the manipulation of salinity of the medium. The increase in salinity (sodium chloride-NaCl) from 0 to 3 g l-1 of the prescribed growth medium resulted in a considerable increase (11.83%) in CPC content. Growth of the organism and the purity of the CPC were not affected at elevated salt concentration. However, a further increase in the salinity (NaCl) from 3 to 7 g l-1 resulted in a decline in the content (26.67%) and purity (31.13%) of CPC. Considering the enhanced growth and CPC content through the manipulation of the concentration of the salt NaCl in the medium, it is concluded that a moderate amount of the salt (3 g l-1 NaCl) in the medium is a feasible and cost-effective approach for obtaining elevated protein biomass and enhanced the yield of the value-added pigment CCPS. [ABSTRACT FROM AUTHOR]

Today's needs of energy are yet globally dominated by fossil energy sources, causing the depletion of non-renewable energy. Alternatively, a potential substitute is the energy of biomass. Spirulina platensis (SP) is a microalgae biomass which, if extracted, will produce solid waste called Spirulina platensis residue (SPR). This research explores the pyrolysis product, produced within the range of 300 - 600 °C, from the pyrolysis of SP and SPR using fixed bed reactors. The influence of temperature on pyrolysis product's yield and characteristics are investigated by using mass balance method and gas chromatography - mass spectrometry (GC-MS) technique, respectively. The results from mass balance method present an optimum pyrolysis temperature of 550 °C to obtain the desired liquid product of bio-oil, presenting the percentage of 34.59 wt.% for SP and 33.44 wt.% for SPR case. Additionally, with the increasing temperature, the char yield decreases for about 30 wt.% and the yield of gas seems to sharp increase from 550 to 600 °C. These tendencies are both applied for SP and SPR source pyrolysis product. Interestingly, the benefit use as fossil fuel substitute might be derived, thanks to high HHV at the bio-oil product (32.04 MJ/kg for SP and 25.70 MJ/kg for SPR) and also at the char product with of 18.85-26.12 MJ/kg for both cases. The additional benefit come from the high content of C in its char product (50.31 wt.% for SPR and 45.26 wt.% for SP) that might be able to be used as an adsorbent, soil softener or other uses in the pharmaceutical field. [ABSTRACT FROM AUTHOR]

Lately, microalgae have been used as natural additives in fish-transformed products to improve their nutritional quality. In this research, the effects of adding Spirulina platensis at concentrations of 0.5, 1 and 1.5% w/v on both the texture and the sensory characteristics of canned burgers were studied. In fact, the addition of Spirulina platensis to fish burgers improves their nutritional composition. Compared to the results of the other fish burger treatments, the treatments that contain 1% of Spirulina platensis had better texture and sensory properties (p < 0.05). Besides, these treatments showed higher swelling ability as well as water and oil holding capacities, due to the important dietary fibers and polysaccharides contents found in Spirulina platensis. No mold or foodborne pathogens were detected in any of the canned burgers up to 8 months of storage at 4 °C. Furthermore, burgers prepared with Spirulina were distinguished by the lowest mean (a* and b*) values (p < 0.05), which shows that the yellow color gradually diminished towards a greenish color. Because of the presence of polysaccharides and pigments (chlorophylls, carotenoids and phycocyanin), Spirulinaplatensis considerably ameliorates the antioxidant activities of the newly prepared fish burgers. On the whole, we can conclude that Spirulina platensis can be used as a nutritious additive to produce new fish-based products with high alimentary qualities. [ABSTRACT FROM AUTHOR]

The selective conversion of biomass into high‐value carbon materials has recently been attracting increasing attraction. In this study, a microalga with a high nitrogen content, namely Spirulina platensis, was used as both the carbon and nitrogen precursors in the synthesis of sponge‐like nitrogen‐enriched carbon materials through a one‐step activation method with NaHCO3 as a green activator. The sponge‐like nitrogen‐enriched carbon materials obtained at different activation temperatures were systematically characterized by using SEM, N2 adsorption‐desorption, XRD, Raman, and XPS techniques. A series of tests were performed to investigate the electrochemical characteristics of the obtained carbon materials to determine their potential use as supercapacitors. The results show that sponge‐like nitrogen‐enriched carbon activated at 700 °C, which has a large BET surface area of 865 m2/g and a high nitrogen content of 7.5 wt%, gave the largest specific capacitance of 234.0 F/g at a current density of 1 A/g in a 6 M KOH electrolyte. High carb: A one‐step activation method is applied to convert nitrogen‐rich microalgae into nitrogen‐containing carbon materials, where NaHCO3 is used as a green activator. The sponge‐like nitrogen‐enriched carbon activated at 700 °C exhibits a large BET surface area of 865 m2/g and a high nitrogen content of 7.5 wt%. It shows a large specific capacitance of 234.0 F/g at a current density of 1 A/g in a 6 M KOH electrolyte when used as a supercapacitor electrode. [ABSTRACT FROM AUTHOR]

The article presents the results of study of the effect of the chemical compound Fe2Se3O9¶6H2O on the growth of cyanobacterium Spirulina platensis, evaluation of its biochemical parameters (proteins, phycobiliproteins, lipids and carbohydrates), as well as the level of iron/selenium accumulation into its biomass. The optimal concentration (30 mg/l) of Fe2Se3O9¶6H2O was determined to induce biomass production of selenium and iron enriched Spirulina platensis. [ABSTRACT FROM AUTHOR]

In the present study, the microalgae Spirulina platensis DRH 20 was cultivated in 4 photobioreactors with lighting intensity of 330 (±13.2) μmol m−2 s−1, 24 h d−1. No additives were added in PBR 1, while CO 2 and phosphoric acid (pH control) were added in PBR 2, phosphoric acid was added in PBR 3, and CO 2 was added in PBR 4. Dry biomass reached a maximum of 20.7 g L−1 and productivity reached a maximum of 4.3 g L−1 day−1 in PBR 2. The highest value of CO 2 biofixation rate was also found in PBR 2, with 7.758 mg L−1 d−1. The highest μ max and the shortest doubling time were found in PBR 4. Regarding bioremediation, percentages between 76.9% and 79% of COD, 90.9 and 99.3% of NH 4 +, 85% and 92%. NO 3 −, were removed. The highest lipid production was recorded in PBR 4 (0.581 g L−1 d−1), which could generate 52.800 gallons of crude oil per year for each hectare cultivated and a biodiesel production yield of 121.7 g kg−1. From the analyses of fatty acids, it was possible to observe that producing biodiesel with the biomass generated in PBR 4 can promote better yields in lipid production and better quality. • Dry biomass of 20.7 g L−1 can be obtained by the addition of CO 2 + phosphoric acid. • It is possible to produce ∼122 g of biodiesel from 1 kg of microalgae biomass. • The maximum volumetric production of total lipids was 0.581 g L−1 d−1. • Annual biofixation 29.6 and 37 t of CO 2 can be obtained. • Biodiesel produced can be used as additives due to its low oxidative stability. [ABSTRACT FROM AUTHOR]

Cultivation of Spirulina platensis in Zarrouk media containing 0-20 g l-1 glucose was studied in a photobioreactor for 30 days using a light intensity of 3 klux. Various parameters were measured to evaluate the enhancement of cell performance with glucose such as cell number, osmolarity, membrane stability, biomass productivity, doubling time, stress intensity, stress tolerance, chlorophyll, protein, carbohydrates, and lipid contents. Based on the results, we concluded that S. platensis is able to grow and produce some ingredients in Zarrouk media containing up to 20 g l-1 of glucose which is the first to be reported. The cell concentration of the mixotrophic cultures (80 cells per mm2) corresponded well to the sum of the autotrophic cell concentrations (50 cells per mm2), showing that the addition of carbohydrate positively effects on the microalgae growth. The continuous operation supplemented with 0.5 g l-1 of glucose (G0.5) led to the maximum cell concentration about 9.06 g l-1 wet and 1.32 g l-1 dry weights. The highest tolerance index, specific growth rate, biomass productivity, cell division, osmolarity and membrane stability index were respectively 102.5%, 0.15 d-1, 0.04 g l-1d-1, 0.26 div d-1, 0.87 osmol kg-1 and 93.8%, obtained in the same treatment. Chlorophyll (6.7 % in G0; 0.046 g l-1 in G0.5), protein (79.9 % and 0.884 g l-1 in G0.5), carbohydrates (55.5% in G20; 0.492 g l-1 in G6) and lipid (53.3% in G10; 0.636 g l-1 in G0) percentages and yields were mostly enhanced in the mixotrophic condition. This study indicated that mixotrophic growth of S. platensis is useful for commercial biomass production. [ABSTRACT FROM AUTHOR]

Conventional extraction methods are able to extract only 50–60% of the total allophycocyanin (A-PC) present in a given biomass. One of the reasons is the resistance offered by the cell membrane for its disruption. The present study is aimed at screening different conventional methods and their combinations (to explore synergy) to arrive at the most suitable methodology for the primary extraction of A-PC from dry biomass of Arthrospira platensis . A synergistic effect was observed on employing ultrasonication in combination with other conventional methods. Ultrasonication with freezing and thawing resulted in the highest A-PC extraction efficiency of 93.11%. The problem of purification of A-PC when extracted along with c-phycocyanin (C-PC), due to same biochemical properties, could be overcome by carrying out ‘ultrasonication followed by sequential extraction employing freezing and thawing’. A-PC with an yield of 40% (devoid of C-PC) with a purity of 1.15 could be extracted, the highest reported till date during primary extraction itself. [ABSTRACT FROM AUTHOR]

The effect of static magnetic field (SMF) on Spirulina platensis growth and its influence on cadmium ions (Cd 2+ ) removal efficiency were studied. Application of 6 h day −1 SMF resulted in the highest significant biomass productivity of 0.198 g L −1  day −1 . However, 10 and 15 mg L −1 of Cd 2+ resulted in significant reduction in biomass productivity by 8.8 and 12.5%, respectively, below the control. Combined SMF showed 30.1% significant increase in biomass productivity over the control. On the other hand, increase of initial Cd 2+ concentration resulted in significant reduction of Cd 2+ removal efficiency, representing 79.7% and 61.5% at 10 and 15 mg L −1 , respectively, after 16 days. Interestingly, application of SMF for 6 h day −1 enhanced Cd 2+ removal efficiency counted by 91.4% and 82.3% after 20 days for cultures with initial Cd 2+ concentration of 10 and 15 mg L −1 , representing increase by 6.3 and 25.3%, respectively, over the SMF-untreated cultures. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the production of biodiesel from two kinds of microalgae Chlorella sp. and Spirulina platensis. Various items such as culture, lipid extraction and the production of biodiesel have been studied. The results showed that the rapid growth of Chlorella sp. from 0.2 to 0.5 gr per liter productivity biomass of cultivation is more suitable than Spirulina microalgae with slow growth of 0.1 to 0.3 gr per liter for the productivity biomass of culture. In comparison to 26.2% lipid content of microalgae Chlorella sp., Spirulina microalgae lipid content and the amount of 14.3 indicate a significant difference. Biodiesel output value was 28.2% by direct transesterification method. According to the results, it could be argued that microalgae Chlorella sp. features make the most suitable microalgae species for biodiesel production. These features include: rapid growth and high productivity, biomass and suitable lipid contents, environmentally easier cultivation rather than other species, suitable fatty acid profiles, having the most common fatty acids compounds (as C14:0, C16:0 and C18:0) in biodiesel. Extraction method had the best performance of extraction by the biomass Bligh and Dyer method. [ABSTRACT FROM AUTHOR]