Expression of Antifreeze Protein in Antarctic Marine Diatom, Chaetoceros neogracile under Various Stress Condition

Abstract

Antarctic diatoms grow well under low temperature and high salinity environmental condition. Their successful growth may due to the part to secretion of Antifreeze protein (AFP) that decreases the freezing point noncolligatively, referred to as thermal hysteresis (TH) activity and an ice crystal morphological change activity. We have isolated a cDNA encoding Antifreeze protein(AFP) from Antarctic marine diatom, Chaetoceros neogracile. Then, we analysed the expression of AFP gene under various environmental stress condition, for instance, freezing, heat and high light stress. The level of AFP transcript was increased by all stress condition. C. neogracile AFP(Cn-AFP) was over expressed in E. coli and partially purified. Recombinant C. neogracile AFPs were shown to display antifreeze activities based on measuring the thermal hysteresis and modified morphology of single ice crystals.