Solid-State Fermentation for The Production of Dextran from Saccharomyces cerevisiae and Its Cytotoxic Effects

Maximum yield of dextran was obtained when using ground date seeds. Different concentrations of date seeds were applied and the highest dextran production was achieved at 6 g/flask. Extraction of dextran was carried out using ethanol. The molecular weight of the purified dextran was 67 kDa by GPC. Spectral analysis showed that dextran contains D-glucose units in a linear chain with consecutive α-(1,6) linkages. The melting temperature (Tm) was 70.56C, and the value of ΔH was -290.57 mJ, as determined by DSC analysis. The TGA clearly showed the thermal stability of purified dextran. The analysis showed three stages of degradation process. An initial loss of about 0.577 mg (2.17%) weight occurred at 30-75°C, second loss of about 0.822 mg (3.1%) weight occurred at 75-125°C and the third loss of about 0.427 mg (1.61%) weight occurred at 125-175°C. Surface morphology of dextran using scanning electron microscopy showed dextran has a crystalline form which is attributed to the presence of hydroxyl groups which increase crystallinity of dextran, also, dextran showed a compact structure characterized by transversal arrangement which reflects brittleness of dextran and seems to have a porous structure. The cytotoxicity assays on human normal melanocytes (HFB 4) revealed no toxic effect. However, a clear decrease in cell survival was observed in case of human liver carcinoma (HEPG 2) and cervical carcinoma (HELA) tumor cell lines. [Tarek A. A. Moussa and Neveen M. Khalil. Solid-State Fermentation for The Production of Dextran from Saccharomyces cerevisiae and Its Cytotoxic Effects. Life Sci J 2012;9(4):2210-2218] (ISSN: 1097-8135). http://www.lifesciencesite.com. 329