Effects of different light spectrums on growth and proximate biochemical composition of Chaetoceros calcitrans and marine Chlorella sp.
The growth and biochemical composition of microalgae is influenced by light, CO2, nutrients, temperature, pH and mixing. The spectral quality of light source plays an important role in the growth of microalgae and their biochemical composition. Light emitting diodes (LEDs) are an alternative for...
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| Format: | Thesis |
| Language: | English |
| Published: |
2019
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/90407/1/IB%202020%2026%20IR.pdf |
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| Summary: | The growth and biochemical composition of microalgae is influenced by light, CO2,
nutrients, temperature, pH and mixing. The spectral quality of light source plays an
important role in the growth of microalgae and their biochemical composition. Light
emitting diodes (LEDs) are an alternative for replacing sunlight and less energy
efficient conventional lights as the spectral wavelengths of LEDs can be customized
according to species requirements and they consume much less energy.
The aim of this study is to examine the growth, proximate biochemical composition
and fatty acid profile of Chaetoceros calcitrans and marine Chlorella sp. In the first
phase, microlagae were cultivated in small scale photobioreactors (1 L) and exposed
to five different spectrums from LEDs – blue, white, green, yellow, red and fluorescent
lamp (FL) as the control. In C. calcitrans, yellow light demonstrated the highest (p <
0.05) specific growth rate. Protein content was found to be the highest in the FLcontrol
treatment followed by blue and red light, and lowest in yellow light. Lipid
content in C. calcitrans was also found to be amongst the highest in yellow along with
blue and green light but lowest in white light. Green light treatment had the highest
carbohydrate content over the other treatments whereas the lowest was found in white
light. The fatty acid content was also found to be influenced by light spectrums.
Chaetoceros calcitrans produced highest amounts of ω3 essential fatty acids under
red light whereas it was green light for poly-unsaturated fatty acids (PUFAs). Based
on the high specific growth rate and lipid production from the first phase, yellow light
was selected for the second phase of the experiment which was conducted in flat panel
photobioreactors (FP-PBR; 60 L). In phase 2, no significant difference was found in
cell density and biomass upon harvest in both yellow and FL-control. However,
yellow light demonstrated a higher protein content over FL-control, but showed no significant difference in lipid and carbohydrate. Yellow light also produced the highest
PUFAs and ω3 fatty acids.
As seen for C. calcitrans, yellow light also demonstrated a higher specific growth rate
in marine Chlorella sp. in phase 1. The highest protein content in Chlorella sp. was
found in red light while the lowest was in FL-control treatment. However, FL-control
showed the highest lipid content. Lowest carbohydrate content was found in red light.
In Chlorella sp., red light produced higher amounts of ω3 and PUFAs and green light
promoted the synthesis of ω6 fatty acids. Based on the high specific growth rate of
Chlorella sp. from the phase 1, yellow light was selected for phase 2 of the experiment
which was conducted in flat panel photobioreactors (FP-PBR; 60 L). In phase 2, no
significant differences were found in cell density and biomass upon harvesting in both
yellow and FL-control. However, yellow light only demonstrated a higher protein
content over FL-control, and was significantly lower in lipid and carbohydrate content.
Yellow light also produced the highest PUFAs and ω3 fatty acids in Chlorella sp. |
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