Usage of microalgaes as a source of chitin

Chitin is a structural biopolymer formed as a result of β1-β4 bonds of N-acetyl-D-glucosamine (GlcNAc) units. Its chemical structure is similar to cellulose and its most widely used derivative, chitosan. However, these three polymers differ from each other due to the presence of different functional groups on their second carbon. Chitin contains acetamide (-NHCOCH3) group attached to its second carbon in its structure. The chitin, which has a wide range of uses can be used in gel form or solid form. Diatoms are single-celled microalgae with cell walls called frustules made of silica and contain some species proven to produce chitin in the form of β-chitin. The most studied diatom genus in this field are Cyclotella and Thalassiosira. In this thesis, a centric diatom species was studied. Intensive culture was formed from the single-celled strain, and chitin was isolated from this culture. The genetic characterization of the obtained diatom species and the structural characterization of chitin were performed. Images of cells and chitin were taken with scanning electron microscopy (SEM) and inverted phase contrast microscopy. The effect of chitin on the viability of fibroblast cells at different concentrations was interpreted by cytotoxicity tests 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and neutral red uptake assays. After characterizations; the diatom cell was defined as a species belonging to the order Thalassiosirales and it was concluded that the material obtained was chitin in the β form. The concentration of isolated chitin was approximately 25 mg/L. The cytotoxicity tests have resulted in chitin not showing any toxic effects up to 50 μg/ml. Keywords: Diatom, chitin, β-chitin, biotechnology