## 3 Results
### Biomass Composition  
Regarding the biomass composition, the proteins, carbohydrates and chlorophyll-_a_ content were evaluated (Table 1). Spirulina is considered an ideal food supplement since it \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Parameters** & **Unit** & **Control** & **MF 1 h** & \(\eta_{\text{l}}\) **(\%)** & **MF 24 h** & \(\eta_{\text{l}}\) **(\%)** \\ \hline X\({}_{\text{max}}\) * & g L\({}^{-1}\) & 1.52 \(\pm\) 0.01 \({}^{\text{a}}\) & 2.12 \(\pm\) 0.16 \({}^{\text{c}}\) & +123.5 & 2.02 \(\pm\) 0.28 \({}^{\text{b}}\) * & +32.9 \\   av\(\text{P}\) & g L\({}^{-1}\) day\({}^{-1}\) & 0.11 \(\pm\) 0.01 \({}^{\text{a}}\) & 0.14 \(\pm\) 0.01 \({}^{\text{b}}\) & +27.3 & 0.14 \(\pm\) 0.03 \({}^{\text{b}}\) & +27.3 \\ \(\mu_{\text{max}}\) & day\({}^{-1}\) & 0.550 \(\pm\) 0.01 \({}^{\text{a}}\) & 0.638 \(\pm\) 0.01 \({}^{\text{ab}}\) & +15.9 & 0.859 \(\pm\) 0.03 \({}^{\text{b}}\) & +56.0 \\   Dt & day & 1.26 \(\pm\) 0.07 \({}^{\text{a}}\) & 0.81 \(\pm\) 0.04 \({}^{\text{a}}\) & \(-34.1\) & 0.83 \(\pm\) 0.05 \({}^{\text{b}}\) & \(-35.7\) \\ N removal rate & mg L\({}^{-1}\) day\({}^{-1}\) & 41.8 \(\pm\) 0.3 \({}^{\text{a}}\) & 51.2 \(\pm\) 0.2 \({}^{\text{b}}\) & +22.5 & 53.4 \(\pm\) 0.4 \({}^{\text{b}}\) & +27.7 \\ Proteins & \%, \(w\) \(w^{-1}\) & 60.41 \(\pm\) 3.41 \({}^{\text{b}}\) & 67.08 \(\pm\) 1.72 \({}^{\text{c}}\) & +12.69 & 53.6 \(\pm\) 2.71 \({}^{\text{a}}\) & \(-11.3\) \\ Carbohydrates & \%, \(w\) \(w^{-1}\) & 14.01 \(\pm\) 1.84 \({}^{\text{a,b}}\) & 11.42 \(\pm\) 0.55 \({}^{\text{a}}\) & \(-18.48\) & 14.99 \(\pm\) 2.09 \({}^{\text{b}}\) & +6.9 \\ Chlorophyll-_a_ & \(\mu\)g mg\({}^{-1}\) DW & 1.11 \(\pm\) 0.15 \({}^{\text{a}}\) & 2.91 \(\pm\) 0.31 \({}^{\text{b}}\) & +161.1 & 2.63 \(\pm\) 0.31 \({}^{\text{b}}\) & +135.8 \\ \hline \hline \end{tabular}
* X\({}_{\text{max}}\) obtained in the 13 th day. Means \(\pm\) standard deviations. Different letters in the same column correspond to significant differences (\(p\leq 0.05\)).  
\end{table} 
Table 1: Growth parameters, protein, carbohydrates and Chl-_a_ contents in _L. indica_ PCC8005 biomass cultivated under control conditions and the MF applied for 24 and 1 h per day. \(\eta_{\text{l}}\) values represent the increase (+) or decrease (\(-\)) according to the MF effect as compared with the control. Figure 5: Consumption of nitrate during the _L. indica_ PCC8005 cultivation under MF action. has a good nutritional profile, making it an alternative source of protein for human and animal consumption [49] since its biomass has a high protein content (around 60-70%), in addition to vitamins and pigments. This high protein content gives several possibilities to increase the nutritional value of food. Some studies demonstrated the protein power of Spirulina in food supplements for both sports performance [50] and for the elderly to consume to provide health benefits [51; 52; 53]. Thus, it appeared important to evaluate the protein content of the biomass produced under MF. The protein content increased by 12% (67.08 \(w\)\(w^{-1}\); \(p\leq\) 0.05) under MF action applied for 1 h per day in relation to the control culture (60.4 \(w\)\(w^{-1}\)). However, the protein content decreased significantly when the MF was applied for 24 h per day (53.6% \(w\)\(w^{-1}\)). [PERSON] et al. [3] also obtained high protein content in the _Spirulina_ biomass cultured with MF (30 or 60 mT), remaining in the range from 56 to 73% (\(w\)\(w^{-1}\)), but with no significant differences between conditions, stating the possibility that the MF acts on protein metabolism. On the other hand, [23] evaluated the phycocyanin content from the biomass of _Arthrospira platensis_ SAG 21.99 cultured under MF action and the authors concluded that in assays with MF action of 24 h per day, its content decreased (\(p\leq\) 0.05), compared with the control and using an MF for 1 h per day.