# The Effect of LEDs on Biomass and Phycobiliproteins Production in Thermotolerant _Oscillatoria_ sp.
## 4 Discussion
Other companies such as Algamo ([[https://www.algamo.cz/index.php/en/homepage/](https://www.algamo.cz/index.php/en/homepage/)]([https://www.algamo.cz/index.php/en/homepage/](https://www.algamo.cz/index.php/en/homepage/)); accessed on 12 November 2022) in the Czech Republic and Yemoja ([[https://yemojaltd.com](https://yemojaltd.com)]([https://yemojaltd.com](https://yemojaltd.com)); accessed on 12 November 2022) in Israel apply indoor cultivation systems with LEDs to maximize the production of metabolites. In the case of phycocyanin production, specifically in _S. platensis_, to the best of the author's knowledge, there is only one indoor production site that uses LEDs to produce phycocyanin, which is in Sardinia, Italy ([[https://www.c-led.it/magazine/en/inaugurati-due-nuovi-impianti-di-coltivazione-di-spirulina-in-sardegna-con-lampade-c-led/](https://www.c-led.it/magazine/en/inaugurati-due-nuovi-impianti-di-coltivazione-di-spirulina-in-sardegna-con-lampade-c-led/)]([https://www.c-led.it/magazine/en/inaugurati-due-nuovi-impianti-di-coltivazione-di-spirulina-in-sardegna-con-lampade-c-led/](https://www.c-led.it/magazine/en/inaugurati-due-nuovi-impianti-di-coltivazione-di-spirulina-in-sardegna-con-lampade-c-led/)); accessed on 12 November 2022). The most studied wavelengths in the production of biomass and phycobilproteins are white [26; 47; 48; 49; 50; 51; 52; 53; 54; 55; 57; 58; 59; 63], red [23; 25; 26; 50; 51; 54; 57; 58; 59; 63], and blue [49; 50; 51; 52; 53; 57; 59]. Other less studied wavelengths are orange [50], green [53; 54], yellow [51; 54; 58], and far-red [62]. In the case of _A. maxima_, different LEDs wavelengths can modulate the final concentration of biomass, with values up to 3.9 g/L (white LEDs) [50] or as low as 0.78 g/L (red LEDs) [30]. In _A. platensis_, white LEDs can increase the final concentration of biomass by up to 6.5 g/L [55], and even yellow and red LEDs (6.6 and 6.2 g/L, respectively) have shown a significant increase in the biomass produced; however, the results obtained from different researchers lack homogeneity among strains of the same species. It is impossible to highlight any trend in the effect of a specific wavelength. These differences may be due to culture conditions used in each strain, such as the culture medium and organic carbon sources (mixotrophic culture). In this work, the mixture of white and red/blue lights (4:1) enhanced the production and biomass and C-PC synthesis in _Oscillatoria_ sp. A possible explanation for the synergistic effect in this strain can be explained by the fact that white LEDs will provide a wide spectrum of light, which will favor biomass production, while the red/blue LEDs will enhance the synthesis of PBPs (CPC-APC and PE) in this strain. Most of the literature focuses on the last two variables, but there is no evidence on the evaluation of the purity of PBPs. Purity is measured by the concentration of each PBPs divided by the absorbance at 280 nm (PBPs/Abs280 nm), which corresponds to the wavelength used to quantify total proteins in the Lowrey and Bradford methods [70]. This PBPs-to-protein ratio helps us understand how well the strain grows since PBPs are also a storage for nitrogen in  
\begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline \multirow{2}{*}{**Strain**} & \multicolumn{2}{c}{**LED**} & \multicolumn{2}{c}{**Biomass**} & \multicolumn{2}{c}{**PBPs**} & \multirow{2}{*}{**Reference**} \\ \cline{2-3} \cline{5-6}  & **LEDs Radiation Color** & & & & **imolumn{1}{c}{**mol m\({}^{-2}\) s\({}^{-1}\)**} & \multirow{2}{*}{**Photoperiod**} & \multirow{2}{*}{**(g/L)**} & \multirow{2}{*}{**Concentration (mg/L)**} & \multirow{2}{*}{**Type**} \\ \cline{2-3} \cline{5-6}  
cyanobacteria [71]. Therefore, lower purities will imply that more protein is synthesized; consequently, less nitrogen will be available to produce PBPs.