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    An Alternative Approach to the Traditional Mixotrophic Cultures of Haematococcus pluvialis Flotow (Chlorophyceae)
    (Korean Soc Microbiology & Biotechnology, 2010) Goksan, Tolga; Ak, Ilknur; Gokpinar, Sevket
    In 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.
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    Comparison of the growth characteristics in two different Spirulina platensis strains
    (Ege Univ, 2006) Kilic, Cenker; Goksan, Tolga; Ak, Ilknur; Gokpinar, Sevket
    The 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.
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    Growth characteristic of Nannochloropsis sp (Eustigmatophyta) in tubular photobioreactor in winter period
    (Ege Univ, Fac Fisheries, 2007) Gokpinar, Sevket; Goksan, Tolga; Cirik, Semra; Ozbas, Bircan
    In 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.
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    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, Sevket
    The 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.
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    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, Tolga
    The 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.
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    Vegetative growth characteristics of Haematococcus pluvialis Flotow at different light intensities
    (Ege Univ, 2005) Goksan, Tolga; Gokpinar, Sevket
    Five 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).