Assessment for long-term cultivation and enhancement on the growth of Dunaliella tertiolecta UTEX LB999 using modified f/2 medium

Abstract

Dunaliella sp. is currently attracted worldwide attention as an alternative source of bioenergy. Even though Dunaliella tertiolecta is known to be cultivated well in f/2 medium at short-term culture experiments in the laboratory, however, it is difficult to increase the growth in certain volume and to maintain the viability of the microalga during a long-term culture period for biomass production. Therefore, in order to enhance the growth and cell viability of D. tertiolecta UTEX LB999 strain during a long-term culture period, we developed the modified f/2 medium and its compositions were optimized as follows: f/2 medium, f medium (2-fold concentration of f/2 medium), f*1.5 medium (3-fold concentration of f/2 medium). The aim of this study was to enhance the growth of D. tertiolecta UTEX LB999 in f/2 medium. Additionally, fatty acid profiles of those 3 culture groups were analyzed using AOAC method.In this study, the growth estimation of the microalga cultured in f/2, f and f*1.5 medium respectively were evaluated for 15-day (short-term) and 42-day (long-term) culture experiments. In the 15-days culture experiments, the final average biomass of D. tertiolecta UTEX LB999 in f/2, f and f*1.5 medium were estimated to be 0.68 g/L, 0.69 g/L and 0.70 g/L, respectively (p>0.05). However, the cell viability and growth of D. tertiolecta UTEX LB999 was considerably decreased in f/2 medium after 15-days. In the 42-day culturet is difficult to increase the growth in certain volume and to maintain the viability of the microalga during a long-term culture period for biomass production. Therefore, in order to enhance the growth and cell viability of D. tertiolecta UTEX LB999 strain during a long-term culture period, we developed the modified f/2 medium and its compositions were optimized as follows: f/2 medium, f medium (2-fold concentration of f/2 medium), f*1.5 medium (3-fold concentration of f/2 medium). The aim of this study was to enhance the growth of D. tertiolecta UTEX LB999 in f/2 medium. Additionally, fatty acid profiles of those 3 culture groups were analyzed using AOAC method.In this study, the growth estimation of the microalga cultured in f/2, f and f*1.5 medium respectively were evaluated for 15-day (short-term) and 42-day (long-term) culture experiments. In the 15-days culture experiments, the final average biomass of D. tertiolecta UTEX LB999 in f/2, f and f*1.5 medium were estimated to be 0.68 g/L, 0.69 g/L and 0.70 g/L, respectively (p>0.05). However, the cell viability and growth of D. tertiolecta UTEX LB999 was considerably decreased in f/2 medium after 15-days. In the 42-day culture