Effect of nutrients on growth and lipid content of dunaliella
Student name: Ms Isha Atray
Guide: Dr Deepti Gupta
Year of completion: 2010
Host Organisation: The Energy and Resources Institute (TERI)
Supervisor (Host Organisation): Dr Vibha Dhawan
Abstract: With a constant increase in the demand and the rapid consumption rate of fossil fuels worldwide, the
need to look for renewable biofuels is now indispensable. Some photosynthetic microalgae have high
intracellular lipid content that makes biofuel an alternate option. Dunaliella cells have been reported
to have 15-45% lipid content under varying conditions. To obtain large scale production of biofuel
from photosynthetic microalgae it is important to be able to culture algae outdoors in unsterilized
conditions. The ability of Dunaliella to grow in medium formed in R.O., de-ionized and tap water was
investigated. The algae could grow in tap water under unsterilized conditions. In order to get high
yield of oil from algae cell mass it is important to standardize growth conditions so as to obtain
maximum biomass. Hence, the effect of different nutrients on the growth of Dunaliella cells was
investigated. Using a different nitrogen source, increasing the NaCl concentration from 0.17 M to 0.4
M increases the growth. Also use of inorganic carbon in the growth medium enhances growth of
algal cells. However, it was found that algal cells cannot assimilate CO3
2-
from the growth medium
while the HCO3
-
form enhances growth. Lipid analysis with these different nutrient compositions was
done. A decrease in the nitrogen concentration of the growth medium leads to an increase in the lipid
content of the cells, from 18 to 24%. It can be seen that the lipid content increases when cells are
subjected to some kind of stress. However, the increase was not much when a combination of
different nutrients was used. Therefore, it is important to maximize growth with respect to lipid
production.
Keywords: Dunaliella, unsterile conditions, lipid content, nitrogen, inorganic carbon
