RESPONSES TO CHANGES IN LIGHT INTENSITY AND SALINITY IN MICROALGA DUNALIELLA TERTIOLECTA

Abstract

The first objective is to identify rate-limiting steps in growth as Dunaliella tertiolecta acclimates to changing light intensity. In high light (HL) to low light (LL) transition, cell count and fatty acid synthesis was significantly higher after 24 h and acetyl-CoA carboxylase could be the rate-limiting enzyme in HL to LL response. In LL to HL transition, genes in the protein processing in ER, protein export, microtubule formation, cell cycle and nucleosome assembly could be rate-limiting in HL response. The second objective is to identify osmolytes present in D. tertiolecta and mechanisms to survive in high salinity condition. At low and intermediate salinity, the total osmotic pressure from glycerol, mannose, D-allose and internal sodium was almost equivalent to that of the medium osmotic pressure. At high salinity, cells increased unsaturated fatty acids and glycerol as well as increased gene expression of nitrate transporters and carbonic anhydrases.