Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Effects of Cultivation Temperature on Protein Production of Selected Spirulina Strains Under Photobioreactor Conditions(Elsevier, 2026) Binkanat, Tahir Burak; Ozkan, AltanSpirulina is cultivated industrially for food supplement applications due to its high protein content and protein quality. This study assessed the influence of cultivation temperature on the productivity of widely accessible, protein-rich Spirulina strains under standardized bubble column photobioreactor conditions, with the goal of identifying strains with consistently high nutritional value across varying temperatures and culture age for outdoor applications. Five strains were first screened for protein content at 30 degrees C, and three with protein contents >60 % dry biomass were selected for cultivation at 25 degrees C, 35 degrees C, and 40 degrees C. Protein content was measured daily to determine variations, and protein quality was assessed at log and stationary growth phases. The metal content was analyzed to assess the toxic heavy metal bioaccumulation potential. At the optimum temperature of 35 degrees C, the strains had similar biomass productivities. However, the protein contents were highly temperature and strain-specific. Based on the strain, under identical process conditions, a relatively stable protein content of around 65 % or a content variation from 30 to 70 % was observed through the cultivation. Growth at 25 degrees C lowered the biomass productivity without affecting the protein contents, and growth at 40 degrees C lowered both parameters. S. platensis UTEX 2340 had consistently the highest protein quality, reflected by its higher cumulative essential amino acid contents and essential amino acid index scores. However, at 35 degrees C, the strain also had a mercury content exceeding the safety limits set for food supplements. These findings demonstrate the importance of strain selection and cultivation temperature in maintaining the nutritional value of Spirulina-based products.Article Citation - WoS: 5Citation - Scopus: 5Screening Diatom Strains Belonging To Cyclotella Genus for Chitin Nanofiber Production Under Photobioreactor Conditions: Chitin Productivity and Characterization of Physicochemical Properties(Elsevier, 2023) Özkan, AltanDiatom species belonging to Cyclotella and Thalassiosira genera have the unique and industrially relevant ability to biosynthesize and extrude pure chitin nanofibers. The current understanding of diatom-based chitin production is narrowed by the complete reliance on the performance of a single strain. This study aims to facilitate the development of a wider understanding for enhanced industrial utility. For this purpose, six Cyclotella strains were cultivated under standardized process conditions of a bubble column photobioreactor, and the resulting productions were characterized in terms of rate and physicochemical properties. A two-stage cultivation protocol was followed where the cells were cultivated under silicon replete and then following its complete consumption under silicon deplete conditions. All the strains produced chitin fibers of β-form with relatively constant average diameters, ranging from 48 to 58 nm. Chitin production rates and final concentrations as well as fiber number densities and length distributions were highly strain-dependent. Dissolved silicon availability controlled chitin biosynthesis: following its depletion, the productivity of all the strains increased drastically. Two strains of marine origin, C. cryptica CCMP 332 and C. cryptica CCMP 333, generated the most favorable outcomes for commercial-scale production and had final concentrations of 272 ± 9 mg/L and 316 ± 12 mg/L, and maximum production rates of 48 ± 2 mg/L-day and 51 ± 2 mg/L-day, respectively. The superior performance of these strains was due to (i) the extrusion of more fibers per fiber port, in the case of C. cryptica CCMP 333 as many as 20.7 ± 1.0. indicating free fiber accumulation in suspension, and (ii) the biosynthesis of longer fibers, mean fiber lengths varied from 15 to 20 μm during cultivation. This study demonstrates the importance of species selection and silicon availability for diatom-based chitin production in terms of rate, final concentration, and nanofiber fiber length distributions.