The effect of initial glucose concentration on growth and lipid
content of marine Chlorella sp. and Nannochloropsis sp. are shown
in Fig. 3. A similar trend of results was observed for both strains.
The cell dry weight increased when the initial glucose concentration
was increased from 0 to 10 g/L, but no further increases were
observed when up to 20 g/L. At the relatively low initial glucose
concentration of 2 g/L, no glucose was detected in the medium at
day 2 (data not shown). At the initial glucose concentrations of
from 4 to 15 g/L, glucose gradually decreased over time and was almost
completely depleted at the end of cultivation. Only at the
highest initial glucose concentration of 20 g/L, glucose did remain
at about 2.2 g/L at the end of cultivation. The lipid content of both
strains decreased sharply when the initial glucose concentration
increased from 0 to 4 g/L. At above 4 g/L of initial glucose concentration,
the lipid content did not change significantly.