The variety of significant gene expression differences found in
the PL-EL comparison is summarized in Figure 4. Of particular
interest is the impact of selection on lipid metabolism that is a
key target for biofuel strain improvement. Our analysis (Fig. S5)
shows that fatty acid biosynthesis (i.e., the precursors of
storage lipids) is significantly down regulated in the EL population
(i.e., fabD and fabH that are involved in fatty acid initiation
and elongation) under the constraint of a high growth rate. Given
this result, we tested whether fast growing EL cells could be
induced to produce lipids by reducing nitrogen in the medium, as
has been shown for many other algae [50,51]. Staining of the
PL and EL populations with the neutral lipid dye Bodipy 493/503