# Indole-3-Acetic Acid Action in Outdoor and Indoor Cultures of _Spirulina_ in Open Raceway Reactors
## 3 Results
### Biomass Characterization  
Experiments with phytohormone supplementation (IAA-I and IAA-O) demonstrated lower protein content than those with control conditions (C-I and C-O) in indoor and outdoor settings. However, since biomass productivity was higher in the conditions with the supplement (IAA-I and IAA-O) compared to controls (C-I and C-O), the protein productivity followed the same trend (Figure 1). In both scenarios, the addition of IAA to _Spirulina_ cultures yielded an approximately 11% increase in protein productivity compared to control experiments under similar conditions. Compared to control experiments in the same environment, the supplemented conditions exhibited a higher carbohydrate concentration and productivity within the biomass (Figure 2). The IAA-I condition showed 99.7% and 144.9% increases in carbohydrate concentration and productivity, respectively, compared to the C-I control. In an outdoor setting, the IAA-O-supplemented condition demonstrated a 72.6% concentration increase and a 114.6% boost in carbohydrate productivity compared to the results obtained from the un-supplemented condition (C-O). Furthermore, outdoor cultivation with phytohormone supplementation (IAA-O) exhibited approximately 225% higher biomolecule content and productivity than indoor conditions (IAA-I). The robust biomass productivity observed in the supplemented outdoor experiment (Table 1) coupled with the substantial carbohydrate content (Figure 2) led to a twofold increase in carbohydrate productivity compared to the outdoor control (C-O) and an eightfold increase over the indoor control (C-I). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Parameters**} & \multicolumn{2}{c}{**Indoor**} & \multicolumn{2}{c}{**Outdoor**} \\  & **C-I** & **IAA-I** & **C-O** & **IAA-O** \\ \hline \hline
**X\({}_{\textbf{final}}\) (g L\({}^{-1}\))** & 2.44 \({}^{\circ}\)\(\pm\) 0.09 & 2.78 \({}^{\circ}\)\(\pm\) 0.29 & 4.60 \({}^{\text{b}}\)\(\pm\) 0.01 & 5.43 \({}^{\text{a}}\)\(\pm\) 0.07 \\
**P\({}_{\textbf{final}}\) (mg L\({}^{-1}\) d\({}^{-1}\))** & 75.3 \({}^{\text{d}}\)\(\pm\) 2.9 & 93.4 \({}^{\circ}\)\(\pm\) 1.2 & 146.5 \({}^{\text{b}}\)\(\pm\) 0.4 & 173.9 \({}^{\text{a}}\)\(\pm\) 2.1 \\
**Fv/Fm initial** & 0.435 \({}^{\text{a}}\)\(\pm\) 0.01 & 0.440 \({}^{\text{a}}\)\(\pm\) 0.01 & 0.445 \({}^{\text{a}}\)\(\pm\) 0.01 & 0.430 \({}^{\text{a}}\)\(\pm\) 0.01 \\
**Fv/Fm final** & 0.385 \({}^{\text{b}}\)\(\pm\) 0.01 & 0.385 \({}^{\text{b}}\)\(\pm\) 0.01 & 0.450 \({}^{\text{a}}\)\(\pm\) 0.01 & 0.440 \({}^{\text{a}}\)\(\pm\) 0.01 \\
**pH initial** & 9.13 \({}^{\text{a}}\)\(\pm\) 0.01 & 9.12 \({}^{\text{a}}\)\(\pm\) 0.01 & 9.09 \({}^{\text{a}}\)\(\pm\) 0.03 & 9.12 \({}^{\text{a}}\)\(\pm\) 0.01 \\
**pH final** & 10.16 \({}^{\text{b}}\)\(\pm\) 0.01 & 10.18 \({}^{\text{b}}\)\(\pm\) 0.01 & 11.13 \({}^{\text{a}}\)\(\pm\) 0.01 & 11.14 \({}^{\text{a}}\)\(\pm\) 0.05 \\ \hline \hline \end{tabular}  
C-I = indoor control culture; IAA-I = indoor cultivation supplemented with IAA; C-O = outdoor control culture; IAA-O = outdoor cultivation supplemented with IAA. Identical superscript letters in the same row indicate that the means do not differ significantly at the 95% confidence level (\(p\)\(>\) 0.05). Data are presented as the means \(\pm\) standard deviation (\(n\) = 6).  
\end{table} 
Table 1: Final biomass concentration (X\({}_{\text{final}}\)) and productivity (P\({}_{\text{final}}\)), and maximum photochemical efficiency (Fv/Fm) and pH of indoor and outdoor _Spirulina_ sp. LEB 18 supplemented with IAA and control experiments. Figure 1: Concentration and productivity of protein (dry basis) of indoor and outdoor _Spirulina_ sp. LEB 18 biomass supplemented with IAA and control experiments. C-I = indoor control culture; IAA-I = indoor cultivation supplemented with IAA; C-O = outdoor control culture; IAA-O = outdoor cultivation supplemented with IAA. Lowercase letters that are identical within columns signify no significant difference in the means of protein content at the 95% confidence level (\(p>0.05\)).