The increase in intracellular neutral lipid during the growth
cycle of isolated microalgae strains was measured via fluorescence
intensity ofNR stained cultures [12] simultaneously to cell
growth. 10 mL of NR was added to 3mL of algal suspensions
whichwas thenvortexed for 1min prior to incubationfor 10min
in darkness at room temperature. NR emits a yellow-gold fluorescence
when dissolved in neutral lipid which is the best
substrate to produce biodiesel [13,14]. Fluorescence intensity of
a stained suspension ofmicroalgae wasmeasured at an excitation
and emission wavelength of 480 nm and 575 nm respectively
using an LS-55 fluorescence spectrometer (PerkineElmer
Corp.) normalized at an optical density of 0.2 at wavelength
680 nm (OD680). The microalgae suspension without NR,
considered as auto-fluorescence, was also measured and subtracted
from that measured as NR fluorescence.