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Öğe An Alternative Approach to the Traditional Mixotrophic Cultures of Haematococcus pluvialis Flotow (Chlorophyceae)(Korean Soc Microbiology & Biotechnology, 2010) Goksan, Tolga; Ak, Ilknur; Gokpinar, SevketIn traditional mixotrophic cultures of microalgae, all the inorganic nutrients and organic carbon sources are supplied in the medium before inoculation. In this study, however, an alternative approach was adopted in Haematococcus pluvialis Flotow, a microalga capable of growing mixotrophically on sodium acetate (Na-Ac). First, the cells were grown under 75 mu mol photons m(-2) s(-1) phototrophically without Na-Ac until the stationary phase and then exposed to five different light regimes by the addition of Na-Ac (e.g., dark, 20, 40, 75, and 150 mu mol photons m(-2) s(-1)). Dry weight (DW), pigments, and especially cell number in alternative mixotrophy (AM) were higher than traditional mixotrophy (TM). Cell number in AM almost doubled up from 21.7 to 42.9x10(4) cells/ml during 5-day exposure to Na-Ac, whereas the increase was only 1.2-fold in TM. Maximum cell density was reached in 75 mu mol photons m(-2)s(-1) among the light intensities tested. We propose that Na-Ac in TM of H. pluvialis can not be utilized as efficiently as in AM. With this respect, AM has several advantages against TM such as a much higher cell density in a batch culture period and minimized risk of contamination owing to the shorter exposure of cells to organic carbon sources. In consequence, this method may be used for other strains of the species, and even for the other microalgal species able to grow mixotrophically.Öğe Biological and Nutritional Applications of Microalgae(Mdpi, 2025) Saritas, Sumeyye; Kalkan, Arda Erkan; Yilmaz, Kadir; Gurdal, Savas; Goksan, Tolga; Witkowska, Anna Maria; Lombardo, MauroMicroalgae are photosynthetic microorganisms that have a rapid growth cycle and carbon fixation ability. They have diverse cellular structures, ranging from prokaryotic cyanobacteria to more complex eukaryotic forms, which enable them to thrive in a variety of environments and support biomass production. They utilize both photosynthesis and heterotrophic pathways, indicating their ecological importance and potential for biotechnological applications. Reproducing primarily through asexual means, microalgae have complex cell cycles that are crucial for their growth and ability to adapt to changing conditions. Additionally, microalgae possess bioactive compounds that make them both nutritious and functional. Thanks to their content of proteins, lipids, carbohydrates, vitamins, and minerals, they play an important role in the development of functional food products, particularly by enhancing nutritional content and product quality. Furthermore, studies have demonstrated that algae and algal bioactive compounds support cardiovascular health, immune function, and gut health, especially in relation to obesity and other metabolic diseases. They also contribute to skin health and cognitive functions, including memory. This review article explores the biological, nutritional, and functional properties of microalgae based on the studies conducted.Öğe Comparison of the growth characteristics in two different Spirulina platensis strains(Ege Univ, 2006) Kilic, Cenker; Goksan, Tolga; Ak, Ilknur; Gokpinar, SevketThe cultivation of Spirulina platensis, which is often used in microalgal biotechnology, has successfully been carried out in our country as well. In this study, the growth characteristics of two Spirulina strains in straight and spiral forms were investigated. In addition, spectrophotometric measurements, which make the measurements of chlorophyll and dry weight more practical, were studied. It was found that all the parameters except the cell count were similar during the experiment. While the spiral/straight form ratio was 2.43 at the beginning of the experiment, it increased up to 5.53 at the end. Spectrophotometric measurements are of importance in terms of practicality in the monitoring of the growth in the cultures. In this respect, a strong correlation was determined between the absorbance values at 680 nm and the amounts of dry weight and chlorophyll (p<0.05). As a result, though there was not a significant difference between the growth parameters of the both forms, the use of straight one would be better due to the problems encountered during harvesting.Öğe EFFECT OF SALINITY ON GROWTH CHARACTERISTICS AND PIGMENT COMPOSITION OF TWO STRAINS OF DUNALIELLA VIRIDIS TEODORESCO: LABORATORY AND OUTDOOR STUDIES(Parlar Scientific Publications (P S P), 2012) Ak, Ilknur; Cirik, Semra; Goksan, Tolga; Koru, EdisIn this study, the effect of salt concentration on growth characteristics and pigment accumulation of two strains of Dunaliella viridis Teodoresco (Ayvalik and Dalyan) which were cultured both at the laboratory and outdoor conditions were studied. The highest growth was found at 2M NaCl (1.33 +/- 0.12 d(-1)) for outdoor conditions. The highest cell numbers were observed at Ayvalik strain for both laboratory (8.06 +/- 0.40 x 10(6) cell ml(-1)) and outdoor conditions (5.83 +/- 0.19 x 10(6) cell ml(-1)). The minimum cell numbers determined at 3M NaCl cultures for laboratory experiments while it was found at 1M NaCl for outdoor cultures. It was measured that the cell volume of laboratory cultures (67.6 +/- 14.4 - 198.7 +/- 9.8 mu m(3)) were higher than outdoor cultures (48.7 +/- 9.7 - 110.5 +/- 4.9 mu m(3)). The total chlorophyll (a+b) and carotenoid contents were the highest at laboratory cultures for all salinity concentrations (p<0.05). The total chlorophyll and carotenoid concentration increased with salinity increase at outdoor conditions. In this study, growth rates, cell density and pigment content of two strains of D. viridis (Ayvalik and Dalyan) was determined and compared both under controlled laboratory and outdoor conditions with different salinity regimes. The results showed that the growth parameters and the pigment composition of D. viridis Ayvalik and Dalyan strains were strongly dependent on salinity.Öğe Effect of sodium acetate and sodium nitrate on biochemical composition of green algae Ulva rigida(Springer, 2015) Ak, Ilknur; Oztaskent, Cenk; Ozudogru, Yeliz; Goksan, TolgaIn this study, the effect of sodium acetate (C2H3NaO2) and sodium nitrate (NaNO3) concentrations on proximate and fatty acid composition of Ulva rigida (C. Agardh) was studied. Two trials were carried out. In the first experiment, the C2H3NaO2 was used as an organic carbon sources and five different concentrations of C2H3NaO2 were added; 0.25, 0.5, 1, 2, and 3 g/l. In the second trial, at the beginning of the experiment, 1 g/l C2H3NaO2 was added all groups, but the nitrogen regimes of the groups were changed. Five different nitrogen concentrations were used; 0.2 g/(l d), 0.3 g/(l d), 0.4 g/(l d), 0.6 g/(l d), and 0.11 g/(l d). According to our results, U. rigida cultivated with C2H3NaO2 and NaNO3 can successfully be used for both animal and human nutrition. The fatty acid methyl esters results showed that fatty acid contents of U. rigida were influenced by carbon (C2H3NaO2) and nitrogen (NaNO3) concentrations. The saturated fatty acids levels of U. rigida cultured in different NaNO3 concentrations were very high. The results indicated that C2H3NaO2 and NaNO3 addition during the culturing had considerable affects on proximate and fatty acid composition of the U. rigida. Using both C2H3NaO2 and NaNO3 offers a balanced fatty acid composition for both animal and human nutrition.Öğe GRACILARIA VERRUCOSA (HUDSON) PAPENFUSS CULTURE USING AN AGRICULTURAL ORGANIC FERTILIZER(Parlar Scientific Publications (P S P), 2011) Ak, Ilknur; Cetin, Zerrin; Cirik, Sukran; Goksan, TolgaIn this study, the effect of an agricultural organic fertilizer on growth, pigment, proximate and agar content of Gracilaria verrucosa (Hudson) Papenfuss was studied. The highest daily growth rate was determined in the agricultural organic fertilizer group as 4.0 % day(-1). Therefore, the growth of G. verrucosa with agricultural organic fertilizer and Conway's medium showed no significant differences (p>0.05). The maximum total chlorophyll content in the agricultural organic fertilizer was higher (20.7 +/- 1.5 mu g g(-1) than in Conway's medium (7.0 +/- 0.2 mu g g(-1)). The maximum protein (42.6 % dw) and lipid contents (7.6 +/- 0.1 % dw) were achieved in the agricultural organic fertilizer group. The significant differences were determined between the groups (p<0.05). The highest carbohydrate (58.1 +/- 0.4 % dw), ash (12.5 +/- 1.0 % dw) and agar (21.9 +/- 0.3 % dw) contents were found in Conway's medium. There was a statistically significant difference between the experimental groups (p<0.05). Consequently, it was seen that the agricultural organic fertilizer is suitable for G. verrucosa culture to produce human and animal food in order to decrease the production cost, but it is unsuitable for agar production.Öğe Greenhouse Cultivation of Gracilaria verrucosa (Hudson) Papenfuss and Determination of Chemical Composition(Central Fisheries Research Inst, 2010) Cirik, Sukran; Cetin, Zerrin; Ak, Ilknur; Cirik, Semra; Goksan, TolgaThe agarophyte Gracilaria verrucosa (Hudson) Papenfuss was cultivated under greenhouse conditions in Modified Johnson Medium over a 5-month period. Biomass productivity ranged between 5.00 g L-1 to 16.37 g L-1 and the highest biomass was obtained in December. Relative growth rate (RGR) varied from 4.03 +/- 1.63 to 1.21 +/- 0.34% day(-1). While the highest percentages of protein were found in December (20.28 +/- 0.94% of dw), the lowest percentages were in March (14.99 +/- 0.14% of dw). Phosphorus content ranged from 101.66 +/- 3.11 ppm (march) to 114.03 +/- 5.44 ppm (december). The lipid concentrations of G. verrucosa were measured within 2.39 +/- 0.77% dw and 2.66 +/- 0.94% dw. The agar yiel were determined between 9.65 +/- 1.12 and 18.64 +/- 2.38% of dw in december and march. The melting and gelling temperatures were stable through the experiment. The highest and the lowest values for both melting and gelling temperatures were 39.00 +/- 0.35 degrees C (december) - 34.00 +/- 0.32 degrees C (march) and 86.50 +/- 0.30 degrees C (march) - 85.50 +/- 040 degrees C (february), respectively. As a result of this study G. verrucosa could be cultivated in greenhouse conditions succesfully. Depending on the high growth rates, high concentrations of crude protein, phosphorus and agar of Gracilaria we conclude that it can be cultivated in greenhouse conditions.Öğe Growth characteristic of Nannochloropsis sp (Eustigmatophyta) in tubular photobioreactor in winter period(Ege Univ, Fac Fisheries, 2007) Gokpinar, Sevket; Goksan, Tolga; Cirik, Semra; Ozbas, BircanIn our country, microalgae cultures in the marine fish larvae hatcheries are carried out in transparent polyethylene bags due to the low investment costs. However, such methods, which are considered unproductive with respect to phototrophic production, result in high production costs due to the requirements of large area and high manpower. In this respect, tubular and panel photobioreactors are the productive systems having higher illumination surface and running at higher photosynthesis rate. In the experiments, BioFence tubular photobioreactor, a commercial microalgae culture system in 600 liter volume and 3 cm outer diameter, was used. The growth of Nannochloropsis sp., grown in the tubular photobioreactor outdoors in both batch and continuous culture modes during 47 days, was observed in the study. Accordingly, the cultures that were begun with a cell density of 16 x 10(6) cells ml(-1), were carried out 22 days in batch mode, and reached to 320 x 10(6) cells ml(-1) at end of the trial. The culture was shifted to the continuous mode when the cell precipitation was observed on the bottom of the tubes due to the high cell density. The continuous mode, which was initiated just after the batch mode, was carried out 25 days. Although the system had a short illumination cycle, e.g., 7 hours a day, due to the location the system set up and the season, the system produced 81 L culture per day at an average cell concentration of 208 cells ml(-1) during the experiment. As a result, it was shown that a tubular photobioreactor outdoors ran more efficient than the bag cultures.Öğe Growth Characteristics of the Alga Haematococcus pluvialis Flotow as Affected by Nitrogen Source, Vitamin, Light and Aeration(Central Fisheries Research Inst, 2011) Goksan, Tolga; Ak, Ilknur; Kilic, CenkerIn the present study, the effects of various inorganic nitrogen sources, light intensities, aeration rates and especially vitamins were investigated in vegetative Haematococcus pluvialis Flotow cultures. The best growth among the nitrogen sources was achieved in NaNO(3) (1.0 g/L) and KNO(3) (0.5 g/L) with cell densities of 25.3 and 26.3x10(4) cells/ml respectively. In vitamin trials, the highest cell numbers were found in 0.1(0.3 mu M), 1.0 (4 mu M) and 0.1 ing/L (0.75 mu M) concentrations for thiamin, biotin and B12 respectively. It was also seen that the use of thiamin alone was sufficient instead of using the vitamin mix. Cell growth was significantly higher in 75 and 150 mu mol photon m(-2) s(-1) illuminations compared to 20 and 40 mu mol photon m(-2) s(-1). As for aeration, optimum airflow rate was 1.0 lpm, while supra-optimum levels ceased the growth, cell diameter and pigment content increased. So, it may play a role as a secondary stress factor on H. pluvialis cells in reddening stage.Öğe Growth of Brachionus plicatilis (Rotifer) on various diets(Ege Univ, 2006) Ozbas, Bircan; Goksan, Tolga; Ak, IlknurIn this study, in which the effects of various food sources on the rotifer Brachionus plicatilis were examined, rotifers were fed with Nannochloropsis sp., yeast (Saccharomyces cerevisiae) and dried Spirulina meal. In the first trial, optimum Spirulina concentration was found to be 0.01 g / 10(6) rotifers per day. In the experimental groups, 5 groups were arranged, e.g., alga, alga+yeast, alga+Spirulina, yeast+Spirulina and yeast/2+Spirulina. In the microscopic observations, it was seen that Spirulina particles were larger than that rotifer can consume. Consequently, the groups that contained alga showed the best growth pattern. Spirulina could not be consumed due to the larger particle size. Regarding the yeast cells, although their size are in the optimum range for rotifer feeding, they exhibited a lower growth rate compared to the groups fed with alga due to the fact that the yeast caused the culture medium to deteriorate.Öğe Removal of methylene blue from aqueous solutions by brown alga Cystoseira barbata(Desalination Publ, 2017) Ozudogru, Yeliz; Merdivan, Melek; Goksan, TolgaThe removal of dyes from wastewater is crucial and considered an environmental challenge. Biosorption is an alternative technology to conventional processes aiming at the removal of toxic metals and dyes from polluted waters. In this study, Cystoseira barbata (Stackhouse) C. Agardh was used to remove the methylene blue (MB) from aqueous solution. The effects of solution pH, contact time and initial MB concentration at different temperatures were investigated. The adsorption reached to equilibrium in 25 min and the pH did not have an important role on the biosorption. The Freundlich isotherm model showed slightly stronger correlation than Langmuir isotherm model especially at 25 degrees C. The maximum adsorption capacity (q(m)) increased in parallel to the rise of temperature and reached to 14.97 mg/g at 45 degrees C. C. barbata can be successfully used for the removal of MB from aqueous solution.Öğe The Effect of Temperature on Protein and Amino Acid Composition of Spirulina platensis(Ege Univ, 2009) Uslu, Leyla Hizarci; Isik, Oya; Sayin, Selin; Durmaz, Yasar; Goksan, Tolga; Gokpinar, SevketThe purpose of this study was to clarify the seasonal variation of protein content and amino acid composition of Spirulina platensis grown in summer and winter. During the study, while the light intensity, pH and salinity were measured daily, the temperature and dissolved oxygen were measured during daytime and at night. While the mean day temperatures were recorded as 33.9 +/- 0.4 degrees C and 18.6 +/- 0.5 degrees C, the mean night temperatures were found to be 29.9 +/- 0.2 degrees C and 14.4 +/- 0.2 degrees C in summer and winter, respectively. The mean light intensity of 848.3 mu mol m(-2)s(-1) was determined in summer. It was 506.26 +/- 48 mu mol m(-2)s(-1) in winter. The protein amount (72.9 +/- 03 %) and the amino acid concentrations of S. platensis grown in summer were found to be higher than in winter. Some of the amino acids, Prolin, Sistin, and Arginine observed in winter, only.Öğe The Effect of the Environmental Factors on the Vitamin C (Ascorbic Acid), E (Alpha-tocopherol), ?-carotene Contents and the Fatty Acid Composition of Spirulina platensis(Ege Univ, 2006) Isik, Oya; Hizarci, Leyla; Sayin, Selin; Gokpinar, Sevket; Durmaz, Yasar; Goksan, TolgaThe purpose of this study was to clarify the seasonal variation of vitamin C (ascorbic acid), E (alpha-tocopherol), beta-carotene contents and fatty acid composition of Spirulina platensis grown in the ponds in the subtropic area. While the light intensity, pH and salinity were measured daily, the temperature and dissolved oxygen were measured in day and night. The mean day temperatures were 33.9 +/- 0.4 degrees C in summer and 18.6 +/- 0.5 degrees C in winter. The mean night temperatures were measured 29.9 +/- 0.2 degrees C and 14.4 +/- 0.2 degrees C in summer and winter, respectively. The mean light intensity of 848.3 mu mol/m(2)/s was determined in summer. It was 506.26 +/- 48 mu mol/m(2)/s in winter. The vitamin C content (39.31 +/- 3.63 mg/100 g) of S. platensis grown in winter was found to be higher than in summer. The alpha-tocopherol content (6.57 +/- 1.18 mg/100 g) was higher in summer. However, -carotene contents were found to be similar both in summer and winter. Fatty acid composition was affected from the ambient factors significantly. The higher.-linolenic acid content (22.221 +/- 0.388 %) was found in summer.Öğe The effects of nitrogen deficiencies on the lipid and protein contents of Spirulina platensis(Academic Journals, 2011) Uslu, Leyla; Isik, Oya; Koc, Kemal; Goksan, TolgaNitrogen deficiencies were studied in Spirulina platensis ( Cyanophyceae) with the aim of determining the effects of the 50 and 100% deficient nitrogen on the lipid and protein contents of the cell under laboratory conditions. S. platensis cultures were grown in Spirulina medium and kept at the constant room temperature of 26 +/- 2 degrees C, illuminated with fluorescent lamps at an irradiance level of 80 mu mol m(-2) s(-1) with photoperiod 16:8 (L:D) and aerated continuously. In the Spirulina biomass harvested at the stationary phase, 67.4, 53.5, 5.6% protein and 5.78, 13.66, 17.05% lipid were recorded for the groups of control, 50% N(-) and 100% N(-), respectively. The highest lipid content and 1.00 gL(-1) dry-weight were recorded from the culture to which treated 100% N(-).Öğe Vegetative growth characteristics of Haematococcus pluvialis Flotow at different light intensities(Ege Univ, 2005) Goksan, Tolga; Gokpinar, SevketFive different light intensities of 50, 100, 200, 400 and 600 mu mol photon m(-2) s(-1) were applied on the vegetative cultures of Haematococcus pluvialis to determine the optimal light intensity, and the growth performance. While dry weight and total carotenoid amounts increased in parallel to the light intensities, total chlorophyll amount increased up to the irradiance of 200 mu mol photon m(-2) s(-1) (2.21 mg L-1), and no change was observed in the higher illuminations (mean value of 2.35 mg L-1). Interestingly, cell count increased in all the groups from the mean value of 3.45 x 10(4) cells ml(-1) on the 15th hour to 5.66 x 10(4) cells ml(-1) on the 18th hour, which coincided with the dark period. In conclusion, astaxanthin accumulation was triggered and cell number was decreased above the illuminations of 200 mu mol photon m(-2) s(-1) (12.73 x 10(4), 16.10 x 10(4), 19.73 x 10(4), 15.90 x 10(4) and 12,89 x 10(4) cells ml(-1) for 50, 100, 200, 400 and 600 mu mol photon m(-2) s(-1), respectively). In the experiment applied five different illuminations, optimal light intensity range for the vegetative stage cultivation of the cells was found to be 50 - 200 mu mol photon m(-2) s(-1), and the best growth was in the light intensity of 200 mu mol photon m(-2) s(-1).
