Showing 13 results for Microalgae
Volume 6, Issue 1 (6-2017)
Abstract
The effect of vitamins C and E in enhancing the shelf life of the algal paste during 12 weeks cold storage (4°C) was assessed. The microalga, Nannochloropsis oculata, was grown in Conway media under 24ºC temperature, 25ppt salinity, and continuous light intensity of 1000- 2000 lux with) and harvested at the logarithmic phase by cream separator centrifugation at 12000 rpm in the form of paste. The algal cell viability was determined by Evans blue dye. The algal paste samples were treated with different vitamin treatments, including: vitamin C and E (0.1%w/w), and an equal proportions of mixed vitamin E and C, and then stored in refrigerator for two months. The results showed that the 95% cell viability of vitamin C treated paste was significantly higher than the control group (p>0.05). FFA and pH in vitamin C treated group was lower than the control treatment. The comparsion of between different treatments during the storage period indicating that it contains vit E had a slower increase than the other treatments in during the storage the time. Overall, it was demonstrated that vitamins functioned as suitable preservatives for the microalgal paste in cold storage (4 °C).
A.r. Zahedi , M. Rashvand M. ,
Volume 9, Issue 1 (1-2018)
Abstract
Aims: Biodiesel is considered as a clean fuel, because it is free of any aromatic compound. In recent years, in order to reduce the cost of production of Biodiesel, many studies have been conducted on the extraction of biofuels from microalgae around the world. Thus, this study was conducted with the aim of investigating the feasibility of optimum temperature for growth of Nannochloropsis Oculata microalga by using image processing system.
Materials and Methods: In this experimental study, a piece of Nannochloropsis Oculata microalga containing 100,000 cells per ml was cultured in 15°C, 20°C, and 25°C. In order to evaluate the growth rate, active microalgae were sampled at 24-hour intervals, and their growth was studied, using machine vision systems. The data were analyzed, using Matlab 2012 and Weka 3 software by multivariable analysis of variance, linear regression algorithm, multilayer perceptron, Gaussian processing and simple linear regression analysis.
Findings: The maximum cell density of Nannochloropsis Oculata on the 8th day was 286.23×104±0.38×105 cells per ml in treatment at 25°C and the minimum cell density was 168.58×104±0.48×105 cells per ml in treatment at 15°C. Specific growth rate was significantly increased at temperature of 25°C compared to the treatments at 15°C and 20°C. Linear regression algorithms (r2=0.84), multilayer perceptron (r2=0.88) and Gaussian processing (r2=0.78) showed good results, but simple linear regression indicated that the algorithm was unsuccessful (r2=0.45).
Conclusion: The image processing technique provides a successful estimation of the growth process of Nannochloropsis Oculata at different temperature levels.
H. Naghoosi, H. Ofoghi, Z. Amini-Bayat , N. Moazami,
Volume 10, Issue 1 (3-2019)
Abstract
Aims: Calcitonin is a small peptide hormone that is produced by parafollicular thyroid cells in human and regulates the metabolism of calcium and phosphorus. It is therapeutically used in treatment of calcium-related disorders and osteoporosis. Recombinant calcitonin production encounters with several difficulties due to instability and low molecular weight, and also needs further treatment in prokaryotic systems. Microalgae have recently garnered high attention for their potential in expression of recombinant proteins. The aim of present study was to assess the ability of Chlamydomonas Reinhardtii to express recombinant human calcitonin.
Materials & Methods: The optimized calcitonin coding sequence and carbonic anhydrase secretory signal was cloned in Pchlamy_3 and Pchlamy_4 vectors. The recombinant plasmids were transformed to wild type and also a cell wall deficient strain of Chlamydomonas Reinhardtii by electroporation. Transformed strains were screened by colony PCR method and selected strains were cultivated to produce recombinant calcitonin. Culture media have been collected after cells growth and assayed by ELISA method.
Findings: Pchlamy_3 vector could not express the target sequence as desired and all the recombinant strains were resulted from Pchlamy_4 vector. The wild type strain also did not show desired yield and only cell wall deficient strain was successfully transformed. The yield of recombinant calcitonin produced by positive strain was about 1 pg/ml.
Conclusion: The results of this study show that the used strategy for secretory production of recombinant calcitonin was successful and it could be used in further studies.
H. Shokrkar, S. Ebrahimi,
Volume 10, Issue 1 (3-2019)
Abstract
Microalgae with stores of carbohydrates are introduced as a promising energy resource to produce In this study, a mixed culture was used for reducing the processing costs. Afterward, nitrogen starvation strategy was used to increase the storage in The application of mixed cultures enhances the economic feasibility of the process due to the elimination of culture sterilization. After harvesting and drying enzymatic hydrolysis of microalgal biomass for extraction Afterward, the enzymatic hydrolysate of microalgal biomass (25, 50, 100g/L) underwent fermentation with Saccharomyces cerevisiae and kinetic models for fermentation were studied. The inhibition of glucose substrate and product was considered in the kinetic model. AQUASIM 2.0 software was used as a tool to simulate the fermentation process. The estimated values of the maximum specific growth rate (μ) Monod constant (Ks) to be 0.281h −1 1.8g/L, respectively. Also, the results indicate that the kinetic model predicted the behavior of the system well.
F. Boshagh , Kh. Rostami , N. Moazemi ,
Volume 10, Issue 1 (3-2019)
Abstract
Introduction: Biofuel production from renewable resource has been extensively paid attention as a sustainable alternative for fossil fuel. As the feed of third-generation biofuels, microalgae can produce variety of lipids, proteins, and carbohydrates in large quantities and in a relatively short time. Regarding the compatibility of these microorganisms with culture diffrent conditions and independence from the seasons of the year, the rapid growth rate, absorbing carbon dioxide and improving air quality, renewablity, non-competing with food supplies, the existence of large quantities of lipid and carbohydrate inside their cells, and abillity of biofuels production, microalgae are known as one of the most suitable options for the biofuels production. Biofuel production from microalgae consists of several stages, including cultivation, harvesting, drying, cell disruption, extraction (lipids or carbohydrates), and the production of biofuels.
Conclusion: In the present study, by reviewing each stage of the biofuels production from microalgae, its importance and application for bioenergy production is discussed. Algal biofuel is not yet competitive with fossil fuels due to its high costs. Researchers are trying to produce economic algal biofuel by improving the growth of microalgae and enriching their reserves of oil and carbohydrates, creating genetic changes, improving the design of photobioreactros, developing harvesting and drying methods, improving methods of extracting lipid and carbohydrate, and producing valuable products.
S.a. Teymouri , A. Habibi, F. Pajoum Shariati , Gh.a. Nematzadeh , H. Delavari Amrei ,
Volume 10, Issue 2 (7-2019)
Abstract
Effluent from dairy industry has a high amount of nutrients such as nitrate and phosphate. In this work nitrate and phosphate removal from treated dairy wastewater in the presence of organic load was investigated. For this purpose, 400ml of synthetic wastewater was inoculated with 2ml of seed culture of microalgae Chlorella salina. During the growth period, nitrate and phosphate concentration in synthetic wastewater was measured for 1, 3, 5 and 7 days with the standard method (APHA). Results showed that removal of nitrate and phosphate by the microalgae from synthetic wastewater was 100% and 95%, respectively. Also, maximum biomass production in 7 days of experiment was about 0.7g/L. These values showed that Chlorella Salina could be potential candidates by showing their intrinsic merit for removal of phosphate and nitrate from dairy wastewater and can be used in treated outlet refinement from the dairy treatment plant to be used before entering to the environment.
Amirhosein Mohammadi, Hamed Abedini,
Volume 11, Issue 2 (6-2020)
Abstract
In this study, the effect of red and blue illumination on continuous culture of two different species of microalgae and cynicocytosis was studied. Comparison of blue and red lights in the cyanobacteria, Synechocystis sp. PCC6803, showed that this specie grows very fast under red light illumination, but it has very slow growth rate under blue light exposure. In spite of huge difference in growth rate, the lipid content and the fatty acid composition of Synechocystis was approximately the same for red and blue light illumination. For microalgae, Chlorella Sorokiniana, the blue light resulted to slightly higher growth rate than the red light. The C18:3 unsaturated fatty acid content was significantly higher for red light illumination compare to blue light illumination. Overall, considering the lower energy requirement for illumination of red, this light is more efficient than blue light for cultivation of Chlorella Sorokiniana.
Morteza Pahlavan Yali, Hjalili Hjalili, Mostafa Noroozi, Yazdan Morady, Ahmad Hallajisani,
Volume 11, Issue 4 (11-2020)
Abstract
The microalgal strain Aurantiochytrium sp. shy contains considerable amounts of poly-unsaturated fatty acids (PUFAs), chiefly docosahexaenoic acid (DHA) with potential pharmaceutical and health-related attributes. Effects of various concentrations of glucose, meat extract, monosodium glutamate and sea salt on the algal biomass and DHA production have been investigated in this study. Maximum algal biomass (7.1 g/l) was obtained when the culture medium contained 60 g/l of glucose, 6 g/l of meat extract, 6 g/l monosodium glutamate and sea salt at 25ppt. Lipid contents of the alga exceeded 30% of its dry cell weight, with palmitic acid and DHA as the most abundant components. When the effect of a single additive was concerned, meat extract was significantly effective, while interaction between meat extract and glucose was the most effective in comparison with other interactions (P < 0.0001). According to the results, glucose can assure more algal and fatty acids production when adequate amounts of meat extract exist in the culture medium. Optimal results attained when the ratios of glucose to meat extract and C/N concentrations were 10 and 5, respectively. Due to its remarkable growth rate and the capability to produce substantial quantities of biomass and fatty acids, Aurantiochytrium sp.shy was found to be a major source of the beneficial ingredients, whose productivity can magnify if its culture conditions is optimized using favorable blend of growth-promoting materials.
Volume 11, Issue 44 (2-2014)
Abstract
One of the problems existing in microalgae production process for the food products is the lack of suitable method for harvesting the microalgae from broth. Nowadays, centrifugation is the only industrial method for microalgae harvesting and its harvesting efficiency is approximately 92%, but the cost of centrifugation is high. In this paper, a new method called electroflocculation was innovated for separation of microalgae from broth and effective parameters in increasing the efficiency of this method were investigated. For achieving this goal, first a special setup which was suitable for microalgae harvesting was designed and fabricated to simulate several harvesting parameters. Then using the designed setup, several parameters such as the mixing type, mixing intensity, current rate, distance and contact area of electrodes, time and power consumption were measured and compared. Results showed that in electroflocculation method the mechanical mixing with 100 rpm intensity and current rate of 5 A has the efficiency of 98%. One cm electrode gap and 640 cm2 contact area were suitable and during 30 minutes the harvesting efficiency of 98% was achieved. The power consumption for harvesting of 1 kg microalgae was 1 kW.h for electroflocculation method which is five times less than typical centrifugation.
Volume 15, Issue 5 (9-2013)
Abstract
One of the important bottle-necks in production of microalgae based biodiesel is the lack of an efficient method for harvesting of microalgae from the culture medium. In this study, the electroflocculation method was developed for harvesting of microalgae Dunaliella cells from culture medium. The effect of several parameters such as the current density, electrical conductivity of culture medium, time, electrode gap, and electrode type on harvesting efficiency and energy consumption were also determined. The maximum harvesting efficiency of this method was 97.44% at EC= 1.35 S m-1 and current density of 90 A m-2 during 3 minutes electroflocculation process in a 300 ml beaker. The maximum efficiency was achieved by aluminum electrodes with 1 cm distance between electrodes and the maximum energy consumption for this practice was 0.621 kW h m-3. It was concluded that electroflocculation is an efficient and cost effective method for microalgae harvesting.
Volume 17, Issue 108 (1-2021)
Abstract
Algae and microalgae are great potential sources of natural compounds that can be used to produce functional foods. Spirulina platensis is one of the edible microalgae with no side effects. Lack of cellulose in the cell wall of Spirulina platensis makes it easy to digest. However, other microalgae do not have this advantage. This property has made Spirulina platensis more valuable. The purpose of this study was to use Spirulina platensis as egg white replacer and investigate its effect on physicochemical and sensory properties of sponge cake during storage time. For this purpose, different egg white ratios (0, 25, 50, 75 and 100% w/w) were substituted in sponge cake formulation with Spirulina platensis powder. The results showed that the addition of Spirulina platensis powder reduced the moisture content, specific volume, porosity and cohesiveness of the samples. Protein, fat, ash, pH and firmness of sponge cake samples increased with increasing amounts of microalgae powder. As the amount of Spirulina platensis microalgae powder increased, overall acceptance of the samples decreased, but this decrease was not significant (p˂0.05). In general, the use of Spirulina platensis powder in small quantities as an egg white replacer, improved the properties of sponge cake.
Volume 18, Issue 117 (11-2021)
Abstract
Nowadays algae, which are Phototroph diatom, are capable of converting nonorganic photos into organic matter, have found many applications in the food, pharmaceutical and sanitary industries. In this study, the effect of adding different levels of Dunaliella salina microalgae biomass on the physicochemical and sensory properties of yogurt during a 21-day storage period was investigated. Dunaliella salina mass powder was added to milk at 4 levels (0, 0.5, 1 and 2% by weight) in the pre-pasteurization stage. Tests including pH measurement, water holding capacity, tissue measurement and colorimetry of samples performed on the first, seventh, fourteenth and twenty-first days after production and evaluation of viscosity and sensory characteristics on the first day after production on the produced yogurt. The results showed that the addition of Dunaliella salina biomass at different levels caused a significant decrease in pH. The water holding capacity of the samples decreased with increasing algal level and storage time (P <0.05). The amount of stiffness, viscosity and color parameters of the yogurt samples showed a significant decrease with increasing algal surface (P <0.05). Sensory evaluations showed that with increasing biomass levels, sensory scores and overall acceptance from consumers decreased. Due to the unique nutritional properties of Dunaliella salina powder, the use of bioactive compounds of this microalgae can also be one of the proposed approaches for use in various food products, including yogurt.
Volume 19, Issue 131 (12-2022)
Abstract
The aim of the present research in the first stage was to extract astaxanthin from Haematococcus microalgae (Haematococcus pluvialis) by combined acid-acetone method and evaluate the efficiency of the process. Then, astaxanthin extracted was nanoencapsulated with maltodextrin-sodium caseinate combined coating and physical, antioxidant and color properties of nanocapsules were evaluated along with the pure form of the pigment (during one month of storage at refrigerator temperature). The results showed that with saponification and primary and secondary purification, the efficiency of the extraction process increased and the amount of pigment during the mentioned steps increased from 8.11 to 21.76 mg/g. According to the findings, the size and zeta potential of the produced nanocapsules were 269.1 nm and +46.71 mV, respectively; In addition, the efficiency of the nanoencapsulation process was recorded as 85.19%. The release profile of astaxanthin from nanocapsules in Simulated Gastric Fluid (SGF) and Simulated Intestinal Fluid (SIF) showed that the release of the pigment varies from 3.21 to 14.28 in SGF and from 18.49 to 41.89% in SIF. Based on the results, the DPPH free radical scavenging activity of pure pigment and nanocapsules (at concentrations of 100 and 200 μg/ml and 0, 15 and 30 days) was ranged from about 21 to 57 and 53 to 70%, respectively. This amount for the reduction power of ferric ion was reported from 0.12 to 0.54 and 0.55 to 0.71 absorbance at 700 nm wavelength, respectively. In the metal chelating activity test, the range of changes was recorded from 23 to 52 and 52 to 75%, respectively. With the nanoencapsulation of the pigment and increasing the concentration, its antioxidant activity increased significantly (p<0.05). Also, unlike the pure form of astaxanthin, the antioxidant activity of its carrier nanocapsules remained constant during storage (p>0.05).
