Meltem Conk Dalay

Comparative Evaluation of Bio-Hydrogen Production From Cheese Whey Wastewater Under Thermophilic and Mesophilic Anaerobic Conditions

Hydrogen production from cheese whey wastewater via dark fermentation was conducted using mixed culture under mesophilic (36°C ± 1) and thermophilic (55°C ± 1) conditions, respectively. The hydrogen yields and specific hydrogen production rates were found as follows: mesophilic: 9.2 mmol H2 /g COD (chemical oxygen demand) and 5.1 mL H2 /g VSS h; thermophilic: 8.1 mmol H2 / g COD and 1.1 mL H2 /g VSS h. The reaction mixture for the mesophilic condition was composed of acetate (0.3–14.7%) and iso-butyrate (85–98%), plus other volatile fatty acids. On the other hand, the reactor mixture for the thermophilic condition was composed of acetate (1–43%) and iso-butyrate (29–46%).

Influences of different stress media and high light intensities on accumulation of astaxanthin in the green alga Haematococcus pluvialis

Haematococcus pluvialis Flotow is used in the aquaculture, pharmaceutical and cosmetic industries. The aim of this study was to compare the effect of various stress media and high light intensities on astaxanthin accumulation. The experimental design was achieved by four different stress media and two different light intensities for 14 days of induction period. The astaxanthin concentrations of 29.62 mg g(-1) and 30.07 mg g(-1) were obtained in distilled water with CO(2) and N-free medium, respectively, with no significant difference between them at 546 micromol photons m(-2)s(-1). Because of the morphological changes of H. pluvialis, microscopic observation was considered during the induction period to facilitate the selection of stress medium. It was clear that the rate of astaxanthin accumulation was much faster in distilled water with the addition of CO(2). The main point is that, this medium is more economical than others, especially for the large-scale productions.

Large-scale bioprospecting of cyanobacteria, micro- and macroalgae from the Aegean Sea

Marine organisms constitute approximately one-half of the total global biodiversity, being rich reservoirs of structurally diverse biofunctional components. The potential of cyanobacteria, micro- and macroalgae as sources of antimicrobial, antitumoral, anti-inflammatory, and anticoagulant compounds has been reported extensively. Nonetheless, biological activities of marine fauna and flora of the Aegean Sea have remained poorly studied when in comparison to other areas of the Mediterranean Sea. In this study, we screened the antimicrobial, antifouling, anti-inflammatory and anticancer potential of in total 98 specimens collected from the Aegean Sea. Ethanol extract of diatom Amphora cf capitellata showed the most promising antimicrobial results against Candida albicans while the extract of diatom Nitzschia communis showed effective results against Gram-positive bacterium, S. aureus. Extracts from the red alga Laurencia papillosa and from three Cystoseira species exhibited selective antiproliferative activity against cancer cell lines and an extract from the brown alga Dilophus fasciola showed the highest anti-inflammatory activity as measured in primary microglial and astrocyte cell cultures as well as by the reduction of proinflammatory cytokines. In summary, our study demonstrates that the Aegean Sea is a rich source of species that possess interesting potential for developing industrial applications.

Process optimization and modeling for the cultivation of Nannochloropsis sp. and Tetraselmis striata via response surface methodology.

The aim of this study was to determine the optimal physical process conditions for the cultivation of locally isolated strains of Nannochloropsis sp. and Tetraselmis striata to achieve maximum growth rate. It was essential to evaluate biomass production at different agitation rates, light intensities, and temperature levels. Central composite design and response surface methodology were applied to design the experiments and optimize the cultivation process for Nannochloropsis sp. and T. striata. The specific growth rate of 0.250 d−1 was obtained for Nannochloropsis sp. cells under the light intensity of 54 μmol photons · m−2 · s−1, at the agitation rate of 151 rpm in 24.5°C. The optimal physical process conditions for T. striata were obtained under the light intensity of 56 μmol photons · m−2 · s−1 in 25.5°C at the agitation rate of 151 rpm in 25.5°C, resulting in a specific growth rate of 0.226 d−1. The predicted values were justified by the verification tests. Good agreement between the predicted values and the experimental values confirmed the validity of the models for the cultivation of microalgal strains. In this article, the noteworthy result was that temperature was a dominant factor in obtaining high chl‐a content for Nannochloropsis sp., whereas the growth of T. striata strongly depended on light exposure.

Determination of Superoxide Dismutase Activities in Different Cyanobacteria for Scavenging of Reactive Oxygen Species

Abstract There is considerable interest in cyanobacteria as sources of antioxidant pigments, antiinflammatory substances, enzymes such as superoxide dismutase (SOD) and vitamins. Antioxidant enzymes have significant role in the removal of reactive oxygen species produced during visible and ultraviolet irradiance stress in cyanobacteria. One of the most ubiquitous protective enzyme is superoxide dismutase (SOD). Most of cyanobacteria are known to have both FeSOD and MnSOD which are associated with photosystem I and II. These enzymes are responsible for scavenging superoxide radicals.Spirulina platensis and Synechococcus nidulans are widely used cyanobacteria as food supplement and cosmetic due to their bioactive compounds. Although the chemical composition of S.platensis has been investigated by many researchers, research on the relationship between protein content and comparison of SOD activity with other cyanobacteria is limited.Among several SOD producing cyanobacteria, the most promising organisms were investigate in terms of SOD activities in this study. The aim of the present work was to investigate and compare the SOD activities of different cyanobacteria including S. platensis, Pseudanabeana sp., S. nidulans and associate with protein contents. SOD activities of these cyanobacteria were determined by xanthine/xanthineoxidase method.Modified Lowry method was used for protein determination. The analysis results showed that the maximum specific SOD activity obtained was 50.4 U/mg from S.nidulans and the minimum specific SOD activity was 18.4 U/mg from Pseudanabeana sp. Total protein amount of S. nidulans, S. platensis, Pseudanabeana sp. was determined as 0.25 mg/ml, 0.27 mg/ml and 0.43 mg/ml respectively. As a result, Synechococcus nidulans was more efficient at scavenging peroxide radicals than Pseudanabeana sp.

In vitro evaluation of Spirulina platensis extract incorporated skin cream with its wound healing and antioxidant activities

Abstract Context: Algae have gained importance in cosmeceutical product development due to their beneficial effects on skin health and therapeutical value with bioactive compounds. Spirulina platensis Parachas (Phormidiaceae) is renowned as a potential source of high-value chemicals and recently used in skincare products. Objective: This study develops and evaluates skin creams incorporated with bioactive S. platensis extract. Materials and methods: Spirulina platensis was cultivated, the aqueous crude extract was prepared and in vitro cytotoxicity of S. platensis extract in the range of 0.001–1% concentrations for 1, 3 and 7 d on HS2 keratinocyte cells was determined. Crude extracts were incorporated in skin cream formulation at 0.01% (w/w) concentration and in vitro wound healing and genotoxicity studies were performed. Immunohistochemical staining was performed to determine the collagen activity. Results: 0.1% S. platensis extract exhibited higher proliferation activity compared with the control group with 198% of cell viability after 3 d. Skin cream including 1.125% S. platensis crude extract showed enhanced wound healing effect on HS2 keratinocyte cell line and the highest HS2 cell viability % was obtained with this concentration. The micronucleus (MN) assay results indicated that S. platensis extract incorporated creams had no genotoxic effect on human peripheral blood cells. Immunohistochemical analysis showed that collagen 1 immunoreactivity was improved by increased extract concentration and it was strongly positive in cells treated with 1.125% extract incorporated skin cream. Conclusions: The cell viability, wound healing activity and genotoxicity results showed that S. platensis incorporated skin cream could be of potential value in cosmeceutical and biomedical applications.

BİYOKÜTLE İÇİN MİKROALG VE SİYANOBAKTERİ’NİN BÜYÜK ÖLÇEKLİ ÜRETİMİ

Mikroalgler ve siyanobakteriler, binlerce yildir ilac, gida ve su urunleri yetistiriciligi endustrisi icin yuksek degerli bilesiklerin dogal bir kaynagi olarak kullanilmaktadir ve buyuk olcekli mikroalg yetistirilmesi, yarim yuzyili askin bir suredir yapilmaktadir. Yakin zamanda yeni mikroalg ve siyanobakteri turleri tanimlanmis ve cesitli urunler icin algal biyokutle yetistiriciligi ticari olcekli sistemlere gecilmistir. Ilk olarak, steril sisede (2L, 5L ve 10L) laboratuvar kosullarinda yetistirilen Arthrospira (Spirulina) platensis ve Phaeodactylum tricornutum kulturlerinin spesifik buyume hizlari ve klorofil-a analizleri yapilmistir. Ardindan ticari uygulama icin buyuk olcekli siyanobakterler ve mikroalg biyokutlesi uretimi icin acik ve kapali sistemler kuruldu. Alg biyokutlesi uretimi icin cevresel kosullar altinda bir acik karistirma tanki ve iki farkli tipte kapali-kultur sistemi veya fotobiyoteraktor (polipropilen torbalar ve plexiglas tupleri) kullanildi. Bununla birlikte, P. tricornutum , dusuk sicakliga karsi iyi direnc gostermis ve dusuk isik siddeti kosullarinda bile buyuyebilmistir. Acik havuz sistemlerinin performansi karsilastirildiginda, entegre sicaklik duzenlemesine sahip dis mekan sistemlerinin, daha iyi iklim kosullarina sahip bolgelerdeki acik havuzlarda yetistirilen kulturlere benzer bir biyokutle uretimi elde edildigi gosterilmistir. Ulkemizde yetistirilen mikroalg ve siyanobakterilerin biyokutle verimliliginin arttirmasi, ileri teknikle tasarlanan ve dusuk maliyetli teknolojilerle gelistirilen fotobiyoreaktor ile saglanabilir.

Screening of fatty acid composition in Nitzschia sp.

Abstract Introduction: The main target of this study was to compare the effects of nitrogen limitation and light intensities on cell growth, lipid content and fatty acid profile of Nitzschia sp. Methods: F/2 medium and N-free F/2 medium were both tested at two different light intensities of 11 and 56 μEm−2s−1 in the internal loop air-lift photobioreactor for Nitzschiasp. Results: The presence of nitrogen led to more cells grown efficiently. Furthermore, the increase in chlorophyll content went parallel to the increase in dry weight. The most abundant saturated and monounsaturated fatty acids were pentadecanoic acid (C15:0) and palmitoleic acid (C16:1) which constituted 17%–42% and 15%–48% of total fatty acids for all growth conditions, respectively. It was recorded that palmitoleic acid was present at higher concentrations than palmitic acid. Discussion and conclusion: The noteworthy finding was that the lipid content increased with increasing the growth rate of Nitzschia sp. under phototrophic conditions.

Optimization of physical parameters for phycobiliprotein extracted from Oscillatoria agardhii and Synechococcus nidulans / Oscillatoria agardhii ve Synechococcus nidulans türlerinden fikobiliprotein ekstraksiyonu için fiziksel parametrelerin optimizasyonu

Abstract Objective: Physical process parameters play a major role in the cultivation of cyanobacteria to provide high yield. The aim of this study was to optimize physical parameters such as light intensity and agitation rate which might affect the phycobiliprotein formations for cyanobacterial strains of Oscillatoria agardhii and Synechococcus nidulans using response surface methodology. Methods: The cyanobacterial strains were cultured in 250 mL flasks containing 100 mL of EM medium in orbital shaking incubator under the temperature of 22±2°C at different light intensities and agitation rates for 10 days. The experimental design was carried out using 22 full-factorial experiments design with four axial points (α=1.414) and five replicates at the central point (65 μmol photons m-2s-1 and 150 rpm), according to the central composite design. Results: The optimization solution of O. agardhii (approximately at 156 rpm under the light intensity of 65 μmol photons m-2s-1) was selected because it resulted in the highest predicted response with the highest desirability. Furthermore, the optimization solution for S. nidulans suggested the phycobiliprotein amount of 9.95 mg/L obtaining at the agitation rate of 185 rpm under the light intensity of 46 μmol photons m-2s-1. The optimized results were reliable and the regions studied were proven to be statistically adequate. Conclusion: High agitation rate stimulated the faster growth than increased the light intensity for the growths of cyanobacterial strains. Ozet Amac: Siyanobakteri kultivasyonunda yuksek verime ulaşmak icin fiziksel proses parametreleri ana rolu oynamaktadır. Bu calışmada amac, yanıt yuzey metodu ile Oscillatoria agardhii ve Synechococcus nidulans turlerinin fikobiliprotein oluşumunu etkileyen ışık şiddeti ve calkalama hızı gibi fiziksel proses parametrelerini optimize etmektir. Metod: Siyanobakteri turleri 250 ml’lik erlenlerde 100 mL EM ortamında 22±2°C sıcaklığında farklı ışık şiddetleri ve karıştırma hızlarında 10 gunluk periyotlarda kultive edilmiştir. Deney tasarımı, 22 faktoriyel kullanılarak CCD ile gercekleştirilmiştir. Bulgular: O. agardhii icin en yuksek tahmini cevap ile uretimin 156 rpm’de 65 μmol photons m-2s-1 ışık şiddetinde olması gerektiği belirlenmiştir. Diğer taraftan, S. nidulans optimizasyon cozumu 9.95mg/L fikobiliprotein miktarına ulaşmak icin uretimin 185 rpm’de 46 μmol fotons m-2s-1 ışık şiddetinde gercekleştirilebileceğini gostermiştir. Sonuc: Yuksek calkalama hızı, yuksek ışık şiddetine kıyasla siyanobakteri turlerinin daha hızlı uremesini tetiklemiştir.