Vol.
32 No.
September 2025 1123-1134 DOI:10.
4308/hjb.
ISSN: 1978-3019
EISSN: 2086-4094
H A Y AT I
Journal of Biosciences Research Article Effect of Light Quality.
Light Intensity, and Cell Inoculum Arrangement on Growth.
Pigment and Carbon Content from Spirulina platensis using LED Light Dianursanti*.
Rayi Mishellia Chempaka.
Nelvina Hartono.
Lulu Habibah.
Swastika Praharyawan Department of Chemical Engineering.
Faculty of Engineering.
University of Indonesia.
Depok 16424.
Indonesia
ARTICLE INFO
Article history:
Received December 24, 2024 Received in revised form March 24, 2025 Accepted March 27, 2025 KEYWORDS:
Biomass Concentration.
Carbon Content.
Light Intensity.
Light Quality.
Pigment Content.
Spirulina platensis ABSTRACT This study evaluates the effect of lighting and cell inoculum in Spirulina platensis cultivation on its growth, pigment composition, and ability to capture CO2.
Different light intensities .
,000, 3,000, and 5,000 lu.
, light quality .
hite, blue, and re.
, and cell inoculum which are shown as OD values .
2, 0.
3, and 0.
were assessed.
The highest growth rate was obtained from red light, followed by white and blue light.
The maximum biomass concentration .
0711 mg/m.
was obtained when red light was used under 5,000 lux light intensity.
The highest carbon content .
1274 mg/ml alga.
was also obtained during red light cultivation under 5,000 lux light intensity.
Meanwhile, the highest chlorophyll .
4365 mg/mg alga.
content was obtained at blue light cultivation under 5,000 lux intensity and OD 0.
5 cell inoculum.
The highest phycocyanin .
0309 mg/mg alga.
was obtained under red light with 3,000 lux light intensity and OD 0.
5 cell inoculum.
It was found that the cultivation conditions to achieve high biomass and high pigment concentration were different.
Copyright .
2025@ author.
Introduction Microalgae are potential sources of biomass production, where they have various applications in the industry, including food, feed, cosmetics, and Among the microalgae.
Spirulina is considered one of the most valuable types of microalgae, which contain 60 to 70% of proteins in dry weight (Lypez-Rodryguez et al.
It also contains vitamins and minerals that usually can be used to incorporate food to increase its nutritional value.
Spirulina is an important source of valuable pigments such as chlorophyll-a and phycobiliprotein .
ne of them was phycocyani.
Chlorophyll is one of the valuable natural green pigments where it can be used as a coloring and has health benefits, such as antioxidant, anti-inflammatory, and antimicrobial (Seo et al.
Zhang et al.
As for Phycocyanin, * Corresponding Author E-mail Address: dianursanti@ui.
it is a blue pigment that can be used in industry for natural food coloring and in the biotechnology field as a fluorescent marker.
It also has health benefits such as neuroprotective, anti-inflammatory, and antioxidant properties (Liao et al.
Hao et al.
Jiang et As a photosynthetic microorganism that needs CO2 for its growth, microalgae can also be advantageous in capturing CO2 and lowering the CO2 concentration in the environment.
Microalgae can be cultivated by different kinds of methods, such as autotrophic, heterotrophic, mixotrophic, and photoautotrophic, which are differentiated by their nutrient supply (Verma et al.
Photoautotrophic and mixotrophic cultivation methods require CO2 and light for the photosynthesis process.
Light serves as one of the most important factors during microalgae and cyanobacterial cultivation, where the light energy is captured and converted to carry out the photosynthesis process (Prates et al.
During large-scale cultivation, generally, the production uses the sun as a light source.
However, cultivating outdoors in largescale production has its limitations, one of which is light irradiance which fluctuates based on season and might affect algal growth and its biocomponent content (Holdmann et al.
Therefore, indoor cultivation is used to solve the limitation.
Indoor cultivation usually uses artificial light as a light source.
One of the artificial lights that is usually used is LED, which has various LEDs' main advantages are high efficiency of electricity conversion, reduced energy consumption, smaller material mass and volume, lower heat dissipation, and a single wavelength (Atta et al.
Some factors need to be considered, such as light sources, nutrition, and cell inoculum, to achieve high yields of biomass and high value-added products.
Light has a great impact on spirulina growth, where light is the main source of energy for Spirulina to perform photosynthesis.
Photosynthesis is performed through the light-harvesting complex, which consists of photosynthesis pigments such as chlorophyll, phycobilisomes, and carotenoids (Liu and Blankenship Each pigment has a different absorption range of light wavelength, where phycocyanin from phycobilisomes absorbs green-yellow .
-630 n.
and orange-red .
-670 n.
In comparison, chlorophyll absorbs violet light .
and red light .
(Devaraja et al.
Several studies have been carried out to evaluate the effect of light colors on the cell growth and pigment production of S.
Prates et al.
found that the highest biomass concentration was obtained with red light in Spirulina.
Jung et al.
also show that the highest cell growth and highest cell densities in Arthorspira platensis are in the order of red > white > green > blue LED light.
It was also found that the highest phycocyanin concentrations were found in the order of blue > white > red > green LED light (Jung et al.
Light intensity has also a great impact on spirulina Some evidence proves the highest spirulina biomass concentration was obtained at the highest light intensity (Gonzylez-Camejo et al.
Chaiklahan et Microalgae growth is proportional to light intensity until reaching a saturation point at which the photosynthetic activity of microalgae achieves its maximum value (Liu and Blankenship 2.
When microalgae are cultivated at low intensity, their growth will be limited.
On the other hand, if the microalgae are cultivated with high intensity and exceed the optimum value, the photosystem will be damaged, causing photoinhibition (Ramanna et al.
Cultivating Dianursanti et al.
microalgae in high cell density may result in lightshading in the culture, which may lead to lowering their growth rate.
The past research of Chaiklahan et al.
found that during the OD of 0.
4 the specific growth rate is higher compared to the higher OD such as 0.
6 and 0.
However, this study did not inform the growth rate if we use OD 0.
5 and lower that 0.
Therefore, in this study we use inoculum with optical density 0.
2, 0.
3, and 0.
In this study, we investigate the relationship between light intensity, light quality, and cell concentration on biomass growth, chlorophyll content, phycocyanin content, and carbon content of S.
The cultivation was conducted in a photobioreactor with a batch process.
To analyze the effects of light type, light intensity, and cell inoculum on the growth rate.
Carbon organic content, pigment content, and biomass content of platensis microalgae, measurements of optical density, carbon content, chlorophyll content, and phycocyanin content will be conducted.
Materials and Methods Pre-Culture Preparation Spirulina platensis The microalgae used in the experiment is S.
which has been used widely in many performance The culture was inoculated in a 2 L cylindrical tube with Zarrouk media.
Zarrouk media was prepared to culture the cyanobacterium, which is composed of .
er liter of distilled wate.
16 g NaHCO3, 2.
5 g NaNO3, 1 g NaCl, 0.
5 K2HPO4, 0.
04 g CaCl2A2H2O, 1 g K2SO4, 2 g MgSO4.
7H2O, and 0.
01 FeSO4.
The prepared medium pH was adjusted to 8-9 and maintained at room temperature .
2AC) and under white continuous light The pre-culture was carried out for more than a week to make a culture stock until the desired amount of culture was achieved.
Photobioreactor (PBR) Setup and Settings Microalgae were cultivated in 2 L photobioreactors.
Photobioreactors material used in this research is glass photobioreactors.
Each of the photobioreactors was equipped with silicon pipe and a plastic pipe that connected to an air pump.
Each of the PBR will be placed at a rack with light source.
The light source used in this research is a light panel with different light colours for each panel, which are red, blue, and white LED lights, as shown in Figure 1.
The distance between the reactors and the illumination source will be adjusted based on the requirement to get the desired light intensity.
HAYATI J Biosci Vol.
32 No.
September 2025 Figure 1.
Spirulina platensis cultivation in Photobioreactor under white light .
, blue light, and red light on different inoculum densities .
2, 0.
3, and 0.
The light panels size was 60 cm y 15 cm .
ength y This panels consist of 36 LED light, where each LED light was 1 watt.
This panels are equipped with dimmer to control light intensity.
Experimental Design Each PBR flask was inoculated with S.
with different optical density values of 0.
The OD value was obtained by diluting culture stock with fresh medium until the ratio is 1:2.
Each flask was then cultivated under different light intensities which are 1,000 lux, 3,000 lux, and 5,000 lux for blue light, red light, and white light .
Continuous lighting .
h light: 0h dar.
and continuous aeration were provided during the cultivation process.
The aeration was provided through an air pump that connected with plastic flexible pipe.
The cultivation was conducted for 54 hours at room temperature .
AC A .
Optical density and pH were measured periodically every 3 hours for 6 hours every day during the cultivation process.
The optical density was measured by spectrophotometer UV-Vis, while pH was measured by pH meter.
This experiment was done duplicate.
The condition in which obtained the highest biomass then subjected to quantification of their chlorophyll, phycocyanin, and carbon content.
Figure 1 presents a schematic diagram of the system used.
Determination of Biomass Concentration and Productivity The growth of S.
platensis was determined by measuring the optical density at 680 nm via spectrophotometer UV-VIS.
5 ml was taken from each cultivation and measured.
If the absorbance was over the value of 1, then the sample will be diluted with distilled water and re-measured.
The dilution is to obtain an OD value between 0.
Measurement of cell dry weight was conducted by centrifuging and rinsing the culture sample.
The supernatant was then taken to dry in the oven at 40AC until the biomass was fully dried.
The dried biomass was then weighed using an analytical balance.
The biomass dry weight is then calculated with the equation:
Biomass concentration W1 - W0 ( L ) = volume Where W1 is the weight of a drying container with algal biomass and W0 is the weight of a drying container without algal biomass.
Meanwhile, the productivity of biomass was calculated according to equation (Gonyalves et al.
( mg ) = Xt -- Xt Dianursanti et al.
Where P is productivity .
g L-1 d-.
and X1 and X0 are the biomass concentration .
g L-.
at times t1 and t0 .
, respectively.
Measurement of Chlorophyll The extraction of chlorophyll was conducted by adapting a method from Khairunnisa et al.
Chlorophyll was measured by reading the absorbance of the solution at 663 nm and 645 nm via spectrophotometer UV-VIS.
The concentration of chlorophyll was calculated using the equation:
Chlorophyll mg = 12.
7 y OD663 - 2.
69 y OD645 .
concentration ml ( ) Chlorophyll concentration Chlorophyll .
content in alga alga dry weight biomass used Where OD663 nm has an absorbance value of 663 nm and OD645 nm has an absorbance value of 645 nm.
Measurement of Phycocyanin The extraction method of phycocyanin was conducted using a combination of maceration and ultrasonication (Tavanandi et al.
A sample of 0.
1 g was suspended with 5 ml of 0.
1 M phosphate buffer pH 6.
8 and incubated for 120 min at room temperature.
The sample was then ultrasonicated with 50% amplitude for 2.
5 min in an onand-off cycle of 1/1s.
The sample was then centrifugated at a low temperature of 4AC for 30 minutes at 5,000 rpm.
The supernatant was then measured at 620 nm and 652 nm with a spectrophotometer UV-Vis.
The phycocyanin concentration was then calculated using the equation:
OD620 - 0.
70 y OD650 Phycocyanin mg concentration ml ( ) Phycocyanin concentration .
content in alga mg alga dry weight biomass used Where OD620 nm has an absorbance value of 620 nm and OD650 nm has an absorbance value of 650 nm.
Quantification of Carbon content The quantification of carbon content was conducted using the colorimetric method provided by Black-Walkley (Walkley and Black 1.
The solution was measured at 600 nm with a spectrophotometer UV-VIS.
Carbon content in microalgae S.
platensis was calculated using the equation:
Corganic carbon (OD.
mg mg alga dry weight sample Where Corganic carbon has a carbon organic content value, and OD600 nm has an absorbance value of 600 nm.
Data Analysis The significance of obtained data is represented by performing ANOVA test then further analysed by TukeyAos The statistical significance .
he probability value.
analysis of all parameters are observed according to p<0.
The ANOVA tests are performed using Origin Results Effects of Light Arrangement and Cell Inoculum on Growth Rate Figure 2 shows the growth rate of Spirulina platensis, which is cultivated under different conditions.
In Figure 2, the growth rate was shown when S.
platensis was cultivated under 1,000, 3,000, and 5,000 lux light intensity.
Generally, it is found that the highest growth rate for each light intensity was found in cultivation under red light, followed by white and blue light.
While red-light cultivation showed an increasing growth rate during the cultivation period, blue-light, on the contrary, showed a decreasing growth rate at every light-intensity cultivation.
It is shown that S.
platensis was having difficulties growing under blue light.
The highest growth rate was obtained during cultivation under red light with 5,000 lux light intensity and 0.
5 cell inoculum, in which the growth rate was up to 0.
0366/ hour at 24h cultivation period (Figure 2C).
While the lowest was found under blue light cultivation at 1,000 lux with 0.
2 cell inoculum.
Based on Figure 2A and B, it showed that under the same light intensity and light qualities, cultivation with cell inoculum of 0.
3 showed to have the highest growth rate compared to 0.
2 and 0.
On the other hand, when platensis was cultivated with red light and white light under 5,000 lux light intensity, the highest growth rate was obtained when cultivated with 0.
5 cell inoculum.
Effects of Light Arrangement and Cell Inoculum on Biomass Dry Weight As shown in Figures 3A.
B, and C, the biomass was shown to increase with the increase of optical density (OD) value in every light quality and light intensity.
The highest biomass obtained from white light was at an OD HAYATI J Biosci Vol.
32 No.
September 2025
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Figure 2.
Growth rate of Spirulina platensis cultivated under different light qualities .
hite, blue, and re.
and different cell inoculum .
3, and 0.
at (A) 1,000 lux, (B) 3,000 lux, and (C) 5,000 lux Dianursanti et al.
White Light.
OD 0.
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Light Intensity Light (Lu.
Intensity Light Intensity Light (Lu.
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g/m.
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OD Blue 2 Light.
BlueBlue Light.
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Figure 3.
Final biomass concentration of Spirulina platensis cultivated light intensity and cell inoculum at (A) white light.
Light Intensity Light (Lu.
Intensitydifferent Light (Lu.
Intensity (Lu.
Blue Light.
OD Blue 2 Light.
Blue ODBlue Light.
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HAYATI J Biosci Vol.
32 No.
September 2025 Effects of Light Arrangement on Carbon Content value of 0.
5 (Figure 3A), where 0.
0422 mg/ml from 5,000 lux.
Under blue light cultivation (Figure 3B), the highest biomass was also obtained from an OD value of 5, where 0.
0043 was found from 5,000 lux.
Under red light cultivation (Figure 3C), the highest biomass obtained was also from OD value of 0.
5, where 0.
0690 mg/ml from 5,000 lux.
Therefore, it is found that the highest biomass was obtained from an OD value of 0.
5 for every wavelength and every light intensity.
Meanwhile, it is shown that under red light cultivation with cell inoculum OD values of 0.
2 and 0.
3, the biomass value seems to be decreasing when the light intensity was increased from 3,000 lux to 5,000 lux.
Figure 4 shows the highest biomass when S.
platensis was cultivated under red light, where the biomass dry weight is 0.
0690 mg/ml for each light intensity, followed by white and blue light.
The biomass concentration was shown to have a growth limitation when cultivated under blue light, which corresponds to the growth rate shown in Figure 2.
It is shown from the statistical analysis where consistently red light results in the highest biomass dry weight at each intensity level, where it is labelled A during 3,000 and 5,000 intensity.
However, the biomass which obtained from red light during 1,000 lux light intensity is not significantly different from white light in 5,000 lux light intensity.
The statistical analysis shows that thereAos no significant difference between biomass obtain from blue light with the increasing of light intensity, where the value was labelled D across all intensities.
White Light
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Arrangement The study was conducted with cell inoculum (OD) 5, which has the highest biomass accumulation.
The effects of lights on chlorophyll content are shown in Figure 6.
As shown in Figure 6 it is shown that the chlorophyll content of S.
platensis is increasing with the increase of light intensity from 1,000 to 3,000 Where the highest chlorophyll content in 3,000 lux was obtained from red light with 0.
9094 mg/mg algae, but it wasnAot significantly different from white light chlorophyll content which is 0.
8578 mg/mg algae, where it shares the same label B.
Furthermore, it is shown that 5,000 lux light intensity increases the chlorophyll content from in blue light cultivation 406 to 1,395 mg/mg.
However, it is also shown White Light.
White 2 Light.
White White Light.
Light.
White 2Light.
White White Light.
Light.
White 3Light.
White 5 Light.
OD 0.
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g/m.
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g/m.
0,0400 Effects of Lights Chlorophyll Content
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Based on Figure 5, it is shown that the light intensity was shown to have a positive linear effect with carbon content.
The highest carbon content was obtained under red light cultivation with 5,000 lux, where the carbon content was 5.
1274 mg/ml algae.
However, at 5,000 lux, the carbon content between red and white light was not significantly different .
abelled A), where under white light the carbon content was 5.
0426 mg/ml algae.
Under blue light, the carbon content was lower compared to red and white light for every light intensity.
1,000
3,000
Intensity (Lu.
LightLight (Lu.
5,000 Light Intensity Light (Lu.
IntensityLight (Lu.
Intensity (Lu.
Figure 4.
Final biomass concentration .
ry weigh.
of Spirulina platensis during cultivation under 0.
5 cell inoculum and different light intensity and light quality Blue Light.
OD Blue 2 Light.
Blue ODBlue Light.
2 Light.
OD Blue OD 0.
Light.
Blue ODBlue Light.
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0,0030
g/m.
0,0040 t .
g/m.
g/m.
D D 0,0030 Dianursanti et al.
White Light
0,0500
0,0450
0,0450
5,0000
0,0450
0,0400
0,0400
0,0400
0,0350
4,0000
0,0350
0,0350
0,0200
0,0150
0,0100
0,0050
Biomass Dry Weight .
g/m.
Carbon Concentration .
g/m.
0,0250 0,0300 3,0000 0,0250 0,0200 2,0000 0,0150 Biomass Dry Weight .
g/m.
0,0500 Carbon concentration .
g/m.
Biomass Dry Weight .
g/m.
0,0500 0,0300 Red Light
0,0250
DE C
DE C
CD C
0,0300
0,0200
0,0150
0,0100
0,0050
0,0050
0,0000
0,0000
0,0000
1,0000
0,0100
0,0000
Blue Light White Light.
White 2 Light.
White White Light.
Light.
White 2Light.
White White Light.
Light.
White 3Light.
White 5 Light.
OD 0.
White
Blue
Red
6,0000
1,000
3,000
Intensity (Lu.
LightLight (Lu.
5,000 Light Intensity Light (Lu.
IntensityLight (Lu.
Intensity (Lu.
Figure 5.
Total carbon organic concentration of Spirulina platensis under various light intensity and light colours 0,0050 1,6000 0,0050 1,6000 1,6000 1,6000 ,0045 0,0045 0,0045 1,4000 0,0040 1,4000 1,4000 1,4000 0,0030 Chlorophyll Content .
g/m.
Chlorophyll Content .
g/m.
Chlorophyll Content .
g/m.
1,2000 1,2000 1,2000 0,0025 ,0020 1,0000 1,0000 1,0000 0,0015 0,0035
Biomass Dry Weight .
g/m.
Biomass Dry Weight .
g/m.
0,0035 0,0030 0,0020 0,0015 0,0010 0,0005 0,0005 0,0000 White
White
White
Light
Light
LightBlue Blue
Light
Blue
Light
LightRedRed Light
Red
Light
Light
White
Blue
Red
0,0000
0,0035
0,0030
0,6000
0,0020
B B B
A A A
B B B
0,0010
0,2000
C C C
0,0005
0,0000
0,0000
0,4000
0,0015
D D D
0,0040
1,0000
D D
0,8000
0,0025
0,0025
0,8000
0,8000
0,8000
0,0010
0,6000
0,6000
0,6000
LightBlue Blue Light Light Blue Light.
OD Blue 2 Light.
Blue ODBlue Light.
2 Light.
ODWhite Blue OD 0.
Light.
ODBlue Light.
3 Light.
OD Blue OD Red Light.
ODBlue 5 Light.
OD 0.
1,2000
Chlorophyll Content .
g/m.
Biomass Dry Weight .
g/m.
0,0040 Chlorophyll content .
g/m.
0,0050 1,000 3,000 Light Intensity (Lu.
Light 3000 intensity 3000 (Lu.
D D D
5,000
Light Intensity Light (Lu.
IntensityLight (Lu.
Intensity (Lu.
Figure 6.
Chlorophyll 0,4000 0,4000 0,4000 content on Spirulina platensis cultivated on different light intensity and light colours E E E
0,2000
0,2000
0,2000
that the chlorophyll content is decreases at 5,000 lux during cultivation under white and red light.
0,0000
0,0000
0,0000
Effects of Light Arrangement Phycocyanin Concentrations However, both blue and red light in 5,000 lux light intensity show similar effects and marked as B.
Discussion Light Light Intensity Light Intensity Intensity (Lu.
(Lu.
(Lu.
The study was conducted with cell inoculum (OD) 5, which has the highest biomass accumulation.
The effects of lights on phycocyanin content are shown in Figure 7.
It is shown that the phycocyanin content of S.
platensis is increasing with the increase of light intensity from 1,000 to 3,000 lux.
Where the highest phycocyanin content in 3,000 lux was obtained from red light with 0.
0309 mg/ml algae.
Furthermore, it is shown that increasing light intensity up to 5,000 lux, lower the phycocyanin content for red light .
mg/m.
and increasing phycocyanin concentration in blue light from 0.
0175 mg/ml to 0.
0245 mg/ml.
E E E
E E E
This study provides insights into the cultivation of platensis under different illumination arrangements and their cell inoculum with artificial LED as a light This study aims to investigate the effects of light intensity, light quality, and initial inoculum concentration on the growth, pigment production, and carbon content of Spirulina platensis.
this cyanobacterium was cultivated under diverse experimental conditions.
As a photosynthetic microorganism.
Spirulina platensis uses light as a main source of energy, where light intensity and light quality have been proven to have a significant impact on cyanobacterial growth and HAYATI J Biosci Vol.
32 No.
September 2025 White Light Phycocyanin Concentration .
g/m.
0,0300 0,0300 0,0250 0,0250 0,0200 0,0200 White
White light
Light
Light
Red Light
Red
Red Light
Light
0,0100
0,0050
0,0000
0,0200
0,0150
0,0250
0,0150
0,0150
Blue Light
Blue Light
Blue
Light
0,0300
Phycocyanin Concentration .
g/m.
0,0350 0,0350 Phycocyanin concentration .
g/m.
0,0350 1,000 3,000 Intensity (Lu.
LightLight (Lu.
5,000 FF content on Spirulina platensis cultivated under different light intensities and light colors Figure 7.
Phycocyanin
0,0100
0,0100
In order to utilize the light as an energy, compared to those who cultivated under low light intensity the light was capture by their photosynthetic pigments .
AAmol/m2/.
Furthermore, the cell's highest biomass
0,0050
0,0050
chlorophyll, phycocyanin, and carotenoids dry weight was obtained from the highest cell inoculum which located in chloroplast.
Each of those photosynthetic (OD 0.
at every light intensity, but the highest was pigments absorb light in specific wavelengths, where obtained from 5,000 lux light intensity.
Meanwhile, it was 0,0000 0,0000 effective to absorbs 550-630 nm and 650-670 also found that there was a visible decrease in biomass weight and growth obtained during5000 cultivation under nm and chlorophyll is 430 nm and 660 nm (Devaraja et dry Light Light Intensity Intensity (Lu.
(Lu.
Therefore, light conditions affect the production 5,000 lux with cell inoculums 0.
2 and 0.
3 compared to of biomass and their metabolite production.
Red light and those who cultivated under 1,000 lux.
This increased blue light were two of those light that are widely used in light intensity may be caused by photolimitation from research, where red light cover 620-645 nm light spectrum cell concentration.
Intense light exposure can induce and blue light covers 440 nm light spectrum (Prates et photoinhibition in algae, which might lead to damage or Therefore, in this study the light qualities used inhibition of photosynthetic processes.
This can result in this study were red, blue, and white, where white light in decreased growth rates and metabolite production was used as control.
As in light intensity, he intensity of and even lead to cell death.
Meanwhile, it is shown that the light intensity used in this study were 1,000, 3,000, and the higher inoculum (OD 0.
did not have a decrease 5,000 lux.
ThereAos certain light intensity that allowed to biomass effect compared to those with OD 0.
2 and 0.
be absorb that are those light intensity in which under the This happens due to the greater biomass contain on the light saturation area.
Further increase intensity than light liquid medium, which means denser cell populations.
saturation area may cause photoinhibition, in which will This denser population may create self-shading which cause stress to the microalgae cell which leads to lower can reduce the light exposure and therefore mitigate the biomass production and death.
It has been proven that photoinhibition effects.
This was in line with the founding for microalgae Spirulina sp.
that light intensity between by Schipper et al.
, where using 50% inoculum 1,000 up to 4,000 lux shows a positive effect towards can minimized photodamage even when using light intensity up to 5,600 AAmol photons/m2/s.
On the other cell productivity (Bhat et al.
, 2.
In this study, from Figure 2 shows that increasing the hand.
Chaiklahan et al.
stated that a higher OD light intensity shows to increase the biomass dry weight value can also decrease the growth rate and may lead to for each light quality and inoculum.
This is possible due to lower biomass production, where it is found that OD 0.
increase of light exposure, therefore enhance their photon has a higher growth rate than OD 0.
This may cause absorption which leads to accelerating photosynthetic increasing self-shading and decreasing transparency of rates and carbon fixation process.
This statement was the algal culture.
therefore, the light cannot penetrate supported by Niangoran et al.
where high light well into the culture.
AAmol/m2/.
produces higher dry biomass It is also found that the highest cultivation was obtained during red illumination.
In contrast, blue LED illumination provides the lowest significant amount of biomass compared to red and white light.
This was also shown in Figure 2, where the red light has the highest growth rate compared to white and blue light.
It is well known that S.
platensis could grow to produce biomass by absorbing energy from light using a photosynthetic apparatus (Chini Zittelli et al.
This result proves that the photosynthetic pigments in Spirulina platensis can absorb the efficient use of red light.
Spirulina platensis consists of photosynthetic pigments such as chlorophyll and phycobilin.
These pigments absorb light and are used for photosynthesis.
Higher light intensity can enhance the production of these pigments, which may eventually enhance photosynthetic efficiency.
There are three possible fates for the absorption of light by chlorophyll First, it is emitted as heat or fluorescence through redistribution into atomic vibrations within the Second, light energy is transferred to nearby photopigments via resonance.
third, photochemical reduction/oxidation, and the electron is transferred to a new molecule.
The first one occurs during saturating light conditions and may potentially damage chlorophyll excitation energy, which leads to the production of free The second and third one occurs under optimal conditions and leads to photosynthetic light reactions (Wang 2.
The highest biomass that was obtained from OD 5, was then further analyse the content of chlorophyll, phycocyanin, and their carbon content.
The highest chlorophyll concentration levels were observed under blue and red-light cultivation, suggesting that the microalgae absorb these wavelengths most efficiently.
The higher chlorophyll content under blue light may be linked to slower growth rates, allowing the cells to have more time to synthesize valuable compounds (Tayebati et al.
These results are consistent with the findings from Kim et al.
, which stated that the microalgae cells have the highest absorption in the peak of red and blue light wavelength, and the high amount of chlorophyll belongs to blue light due to larger cells produced.
The cultivation under blue light conditions may leads to stress growth conditions which trigger microalgae to produce phycocyanin higher as an adaptive response.
When microalgae cultivated under a stress conditions, such as light deficiency or nutrition excess.
Spirulina tends to diver their energy to the productions of secondary metabolites, including phycocyanin as a survival strategy.
The energy produced from blue light is used more for Dianursanti et al.
pigment synthesis rather than cell growth processes such as cell division and multiplication (Sohani et al.
This may explain why during Spirulina sp.
under the blue light, the increase of phycocyanin is higher even though the biomass concentration is low.
Furthermore, it is shown that red light promotes the production of phycocyanin higher than using blue light and white light.
It is in line with the finding from Tayebati et al.
, where the highest phycocyanin concentration was found when cultivated under red light.
Also, it is found that despite promoting biomass growth, when Spirulina platensis was cultivated under high red-light intensity, the chlorophyll and phycocyanin content was reduced.
Red light is strongly absorbed by chlorophyll and phycocyanin pigments, increasing the risk of giving overload energy within high light intensity.
This energy overload might accelerate photodamage to photosystem II (PSII) and lower the pigment biosynthesis pathways (Maali et al.
, also triggering carotenoid synthesis which divert resources from chlorophyll and phycocyanin production.
Niangoran et al.
mentioned that an increase in light intensity induces a decrease in the photosystem concentration of the thylakoid membrane and a decrease in the size of the photosystem II (PSII).
Therefore, there is a trade-off between chlorophyll and phycocyanin pigment biosynthesis and biomass accumulation.
High growth condition conditions can suppress pigment production due to resource allocation and metabolic shifts (Depraetere et al.
It is known that during the photosynthesis process, microorganisms use energy from light to convert CO2 into chemical energy and sugar, which is then called a carbon fixation process.
Microalgae are no exception to this In this study, it was found that the highest carbon content was obtained from the highest biomass dry weight, which was obtained during cultivation under red light with 5,000 lux and cell inoculum 0.
A finding from (Zhu et al.
stated that the ability of microalgae to fixate CO2 is linearly related to biomass production and growth rate.
This phenomenon can be explained by the fact that photosynthesis has two phases, which are light reactions and dark reactions.
The process of carbon fixation occurs in the Calvin cycle, specifically in the C3 This cycle requires ATP energy to reduce energy levels and consumes NADPH to convert carbon dioxide into glucose (Lokstein et al.
This indicated that the ATP productivity obtained from the light reaction on red and white light was higher than that of blue light.
Lower ATP production that happened in the blue light.
Therefore, the carbon fixation activity in blue light was HAYATI J Biosci Vol.
32 No.
September 2025 lower than in red and white light.
The lower production of ATP in blue light can be caused by the limited blue light spectrum that is absorbed by the protein pigment, which plays a significant role in capturing light and delivering it to photosystem I.
Meanwhile, red light and white light may have a better spectrum to be captured by the protein pigment, especially red light that have the highest amount of carbon The red light is easier to capture by protein pigment because the light spectrum from the red light that ranges from 620-645 nm right covers the spectrum of light absorption of phycocyanin (Jiang et al.
Therefore, it efficiently absorbs red-light energy, which contributes to increased biomass accumulation and carbon In conclusion, the results investigated the effects of light intensity, light quality, and initial inoculum concentration on the growth, pigment production, and carbon content of Spirulina patensis using artificial LED light sources.
This study revealed that increasing light intensity generally enhanced biomass dry weight, likely due to increased photon absorption and photosynthetic However, at high light intensity .
,000 lu.
, photoinhibition occurred in lower inoculum densities (OD 0.
2 and 0.
, resulting in decreased biomass.
Red light proved most effective for biomass production and carbon content, as well as in phycocyanin concentration.
Meanwhile highest chlorophyll content can be found under blue and red light.
However, high intensity in red light might reduce chlorophyll and phycocyanin content, which likely due to photodamage.
Overall, this study shows that red light was identified as the most effective light quality, while the optimal light intensity and inoculum density must be carefully balanced to avoid photoinhibiton.
Further research might need to be done in the field to explore other biomass compositions as well as the morphological changes with the arrangements of Furthermore, further study which conducted with different light spectrum, different light source, as well as regulations of media cultivations can be done to further understand the effect of those alteration towards Spirulina growth and their biochemical compositions.
In addition, an optimization study must be conducted to obtain the optimal condition to cultivate Spirulina to obtained high biomass and their biochemical The energy produced from the light can also be calculated for further understanding.
This further research may lead to deepen the understanding of how light and cell concentration made changes to S.
Acknowledgements The authors thank the Laboratory of Bioprocess.
Department of Chemical Engineering.
University of Indonesia for all its facilities.
References