No abstract

Microalga, Dunaliella salina 1650 was selected to produce hydrocarbons that may possibly substitute for fossil fuels in the near future. It can produce 0.22 (mg/L) of hydrocarbons over 20 d batch cultivation, maintaining 1.32 (g-dry wt./L) of cell density. Its productivity was similar to that from Botryococcus braunii, which was known to economically produce liquid fuels. Optimal growth conditions for the alga were also determined as pH 7.2, 28 degrees C, and 0.00034 (Kcal/cm2/h) of light intensity. It was shown that the hydrocarbon production from the alga was closely related to cell growth, except for the later periods of batch cultivation. Better hydrocarbon production was observed during light periods in light/dark cycle cultivation. Under chemostat conditions, maximum steady cell concentration was maintained as 1.1 (g-dry wt./L) at 0.12 (1/d) of dilution rate. The system reached to the steady state after 30 d of the cultivation. The maximum specific hydrocarbon production rate, 0.024 (mg/cell/d) was also obtained under this condition. It proves that the hydrocarbon production from D. salina 1650 can compete with that from B. braunii.