Characterization of exopolysaccharides (EPS) isolated from cyanobacteria species from Turkey waters and investigation of their potential use in cosmetics industry

The objective of this thesis is to investigate and characterize EPSs of different Cyanobacteria species, isolated from different regions of Turkey and explore their potential use in cosmetic industry. Monosaccharide composition, functional groups, and crystal structure of the EPSs produced by cyanobacterial species (55 and 72) were determined by HPLC, FT-IR and XRD, respectively. Additionally, their antioxidant activity, moisture absorption and moisture retention ability, and tyrosinase inhibition activity were evaluated. As a result of 16S rRNA sequencing, the strains were identified as Chlorogloeopsis fritschii (55) and Pseudanabaenaceae cyanobacterium (72) with >98.9% similarity. Both cyanobacteria species yielded high amount of EPS with 888.0 mg/L and 776.8 mg/L of extracted EPS from 55 and 77, respectively. The main component of the EPS molecules detected was rhamnose, glucose, arabinose, mannose, xylose, and galactose in different ratios. Rhamonse was the most dominant monosaccharide. Both EPSs were found to have an antioxidant activity with 80% of DPPH scavenging potential and 8-11% of total antioxidant capacity. Moreover, they both showed strong moisture absorption and retention properties compared to chitosan and urea. Additionally, 55 had a tyrosinase inhibition activity with 10% at a small concentration of 2 mg/mL. The results suggest that Cyanobacteria produced high amount of EPS and cyanobacterial EPSs are promising candidate for use as a potential natural ingredient in cosmetics with their antioxidant and antityrosinase activities as well as moisture absorption and moisture retention capacities.