# The Effect of LEDs on Biomass and Phycobiliproteins Production in Thermotolerant _Oscillatoria_ sp.
## 3 Results  
The results for biomass production using different LEDs are shown in Figure 2. The strain grew in all the LED configurations, with better results than in fluorescent lamps (0.49 g/L). Cool white and red:blue (4:1) LEDs increased the final concentration by up to 0.7 g/L; however, according to the ANOVA analysis, a higher difference was observed (<0.0001) in the biomass produced using the mixture of white/red:blue, with up to three times the concentration of the control (1.3 g/L). The effect of the different LEDs on the concentration and purity of the different phycobiliproteins (C-PC, APC, and PE) can be found in Figure 2. Unlike biomass, C-PC (Figure 3a) (\(\%w/w\)) in _Oscillatoria_ sp. UFPS_001 shows no difference between the cool white and red:blue LEDs and the fluorescent lamps--with values between 7.5 and 7.8% (\(w/w\)); however, the white/red:blue mixture significantly increased the final concentration (10% \(w/w\)). In the case of APC (Figure 3b), the ANOVA analysis shows that white LEDs and the mixture of white/red:blue are significantly different (<0.0001) compared to the control, with values higher than 3.5% (\(w/w\)). The same behavior occurs with the PE (Figure 3c), where the same LED configuration increases the final content of PE. In the case of purity, the ANOVA analysis found that the mixture of white/red:blue increased the purity for C-PC, APC, and PE compared to the fluorescent lamps that were used as controls; however, no statistical differences were obtained when comparing the tested LEDs configurations. Figure 2: Biomass is produced under different LEDs configurations. According to the previous results, the white/red:blue LEDs configuration was used to determine the effect of intensity and the light:dark cycle. In the case of biomass concentration (Figure 4), it was found that _Oscillatoria_ sp. grows better at low light intensities. An ANOVA analysis showed that intensities up to 80 umol m\({}^{-2}\) s\({}^{-1}\) significantly (<0.0001) improved the biomass concentration compared to the control (up to 1.4 g/L). On the other hand, higher intensities significantly reduced the final biomass concentration. The effect of the LEDs' intensity on the concentration and purity of C-PC, APC, and PE can be found in Figure 4. The concentration of C-PC (Figure 5a) of _Oscillatoria_ sp. behaves like the biomass, where 80 umol m\({}^{-2}\) s\({}^{-1}\) significantly improves the C-PC concentration by up to 8% (\(w/w\)) in comparison with other light intensities. In the case of APC (Figure 5b), the ANOVA analysis shows no significant difference between the intensities evaluated, except at 180 umol m\({}^{-2}\) s\({}^{-1}\); in this case, at higher light intensities, the concentration of APC is  
Figure 4: Biomass concentration under different intensities of white/red:blue LEDs. Figure 3: The concentration of phyocyanin (C-PC) (**a**), allophyocyanin (APC) (**b**), and phycoerythrin (PE) (**c**) and their purity (**d–f**) under different LEDs configurations. significantly reduced. On the other hand, the concentration of PE is substantially increased at 80 \(\upmu\)mol m\({}^{-2}\) s\({}^{-1}\) compared to the control and the different intensities tested. In the case of purity, the ANOVA analysis found that the mixture of white/red:blue increased the purity for C-PC, APC, and PE compared to the fluorescent lamps that were used as controls; however, no statistical differences were obtained when comparing the tested LEDs configurations. The previous results highlighted the intensity of 80 \(\upmu\)mol m\({}^{-2}\)s\({}^{-1}\) for evaluating the lightdark cycle. According to the results from the ANOVA analysis shown in Figure 6, when _Oscillatoria_ sp. OSCI_UFFS001 is exposed to more extended light regimes at 80 \(\upmu\)mol m\({}^{-2}\) s\({}^{-1}\), the biomass increased significantly (<0.0001) by up to 1.6 g/L (24:0 photoperiod) in comparison with the control, which used fluorescent lamps at 100 \(\upmu\)mol m\({}^{-2}\) s\({}^{-1}\) (0.49 g/L, 12:12 photoperiod).