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Influence of varying nitrogen levels on lipid accumulation in Chlorella sp.
Kiran, B.; Pathak, K.; Kumar, R.; Deshmukh, D. & Rani, N.
Abstract
Microalgal lipids can be enhanced through
varying nitrogen (N) content, and limited supply of nitrogen
source seems to be valuable approach for increased
lipid accumulation in microalgae. In this study, Chlorella
sp. IM-02 was observed under fluorescence microscope for
increased number of lipid bodies under nitrogen scarcity.
Fourier transform infrared spectroscopy was used to
determine spectral changes due to varying lipid content
under nitrogen-starved (N0, without sodium nitrate),
nitrogen-limited (N0.1, N0.25, N0.5 and N1.0 representing
0.1, 0.25, 0.5 and 1.0 g/L of sodium nitrate, respectively)
and nitrogen-sufficient (N1.5, i.e., 1.5 g/L sodium nitrate)
setting. Chlorophyll content was also monitored under
these conditions as growth indicator. Various biochemical
components viz. total carbohydrates, total proteins and
total lipids were also estimated under varying nitrogen
levels spectrophotometrically. On fourth day itself, maximum
lipid productivity was observed in case of N0.5, which
is having one-third of nitrogen concentration present in
original growth media, BG-11. This concludes N0.5 as
suitable nitrogen provision for better production of lipids in
Chlorella sp. IM-02 without much compromising the biomass
production as both growth and lipid quantity are key
parameters affecting the lipid productivity of any
microalgal strain.
Keywords
Microalgae; Nutrient stress; Wastewater; Fluorescence microscopy
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