DOI: 10.5281/zenodo.14282029
title: Effect of differnt light spectra on Spirulina ULC 0444

description: Effect of Light Colors on Spirulina platensis Growth and Bioproduct AnalysisThis dataset examines the effect of light colors on the growth, biomass productivity, pigment content, and lipid profiles Arthrospira platensis strains (ULC 0444) cultivated under controlled conditions. The study focuses on optimizing microalgae performance using brewery effluent as a cultivation medium and exploring its potential for pigment and biodiesel production.

The ULC 0444 was sourced from BCCM pre-cultivated in Zarrouk medium until an optical density (OD750) of 0.2 was achieved. Brewery effluent that was enriched with Zarrouk medium nutrients (NaHCO3, Na2CO3, NaNO3, K2SO4, Na2HPO4, MgSO4) was used for the investigation.

Experimental Design:A 10% inoculum was prepared and cultivated in transparent acrylic tubular reactors (10 cm diameter, 50 cm height) illuminated by commercial 5050 SMD LEDs. Light intensities were set to 50 μmol·m⁻²·s⁻¹, with colors (red, blue, white, and pink) provided by remote-controlled presets. Cultures were maintained at 25 ± 2 °C and aerated with filtered atmospheric air. Growth was monitored daily, and performance metrics such as maximum specific growth rate (μmax) and biomass productivity (P) were calculated.

 

Growth and Biomass AnalysisGrowth was assessed using OD750, and dry weight (DW) was determined using the formula:







 



DW = 9.9040 * OD + 0.7440



Biomass productivity was calculated as:



P = (Xf - Xi) / (tf - ti)



Pigment Extraction and QuantificationOn day 14, phycocyanin was extracted using freeze-thaw cycles in sodium phosphate buffer (50 mM, pH 7). Phycocyanin content (Cpc) was quantified spectrophotometrically using a Shimadzu UV-1280 UV-VIS Spectrophotometer at 652 nm and 615 nm:



Cpc = (A615 - 0.474 * A652) / 5.34



Extraction yield (Ypc) was determined as:



Ypc = (Cpc * VPBS) / DW

 




Lipid Extraction and FAME Analysis

Lipids were extracted using a methanol-chloroform-water method and transesterified for fatty acid methyl ester (FAME) analysis. Gas chromatography (Agilent 7820A) with a Flame Ionization Detector (FID) was used to quantify FAMEs. Calibration employed the Supelco 37 Component FAME Mix.



Biodiesel Property Evaluation

Key biodiesel properties were calculated using established formulas:

Degree of Unsaturation (DU):



DU = SUM(MUFAs + 2 * PUFAs)



Iodine Value (IV):



IV = SUM((N% * D * 254) / M)



Saponification Value (SV):



 

SV = SUM((N% * 560) / M)



Cetane Number (CN):



 

CN = 46.3 + (5458 / SV) - (0.225 * IV)



Long-Chain Saturation Factor (LCSF):



LCSF = (C16_0 * 0.1) + (C18_0 * 0.5) + (C20_0 * 1) + (C22_0 * 1.5) + (C24_0 * 2)



Cold Filter Plugging Point (CFPP):



 

CFPP = (3.1417 * LCSF) - 16.477



Higher Heating Value (HHV):



HHV = 49.43 - 0.015 * IV - 0.041 * SV



Oxidative Stability (OS):



OS = 117.9295 / C18p + 2.5905



Where:



DU: Degree of unsaturation

MUFAs: Monounsaturated fatty acids

PUFAs: Polyunsaturated fatty acids

N%: Proportion of each fatty acid

D: Number of double bonds

M: Molecular mass

C16_0, C18_0, etc.: Weight proportions of saturated fatty acids

C18p: Combined weight proportion of linoleic (C18:2) and linolenic acids (C18:3)