## 2 Materials and Methods
### Experimental Setup for Autotrophic and Mixotrophic Culture under Different Light Colors  
The study was divided into two series of experiments. The first set of preliminary experiments studied the impact of three light colors: Red (R), Yellow (Y), and White (W) in both mixotrophic and autotrophic conditions under the growth conditions explained above. All the experiments were conducted into 250 mL Erlenmeyer flasks containing 50 mL of liquid media with and an initial inoculum size of 0.2 OD. For mixotrophic cultivation, glucose or glycine was added to the L1 media at a concentration of 1%, which were labeled as 1 and 2, respectively. The experiment identifications are shown in Table 1. In this experiment, all the cultures were exposed to the conditions for the complete culture duration (i.e., from day 1 to day 10). We harvested the cultures at day 10 during the stationary phase.  
In the second series of experiments, the microalgae culture in autotrophic growth conditions was exposed to a light shift from red light to white light in different growth phases (Table 2). For this, _P. tricornutum_ culture was submitted to red light treatment during the specific growth phase i.e., lag, exponential, stationary, and then cultures were exposed to white light labeled as RT1, RT2, RT3, and RS (Table 2). All experiments were done in triplicate. All the inoculum for these experiments were grown in control white light.  
\begin{table}
\begin{tabular}{l c c c} \hline \hline \multirow{2}{*}{**Light**} & \multirow{2}{*}{**Autotrophic**} & \multicolumn{2}{c}{**Misotrophic**} \\ \cline{3-4}  & & **\%** **Glucose** & **\%** **Glycine** \\ \hline White (Control) & W & W1 & W2 \\ Red & R & R1 & R2 \\ Yellow & Y & Y1 & Y2 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Summary of _P. tricornutum_ culture conditions and experiment identifications. _P. tricornutum_ was cultured in L1 media, and all experiments were done in triplicate.  
\begin{table}
\begin{tabular}{l c c} \hline \hline \multirow{2}{*}{**Treatment**} & \multicolumn{2}{c}{**Description**} \\ \cline{2-3}  & RT1 & Red light exposure only during the lag phase (1\({}^{\text{st}}\)-6\({}^{\text{th}}\) day) \\ RT2 & Red light exposure only during the exponential phase (4\({}^{\text{th}}\)-7\({}^{\text{th}}\) day) \\ RT3 & Red light exposure only during the stationary phase (\({}^{\text{th}}\)-10\({}^{\text{th}}\) day) \\ RS & Red light until the end of the exponential phase (1\({}^{\text{st}}\)-6\({}^{\text{th}}\) day) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Overall experimental plan of four culture conditions (red light treatment 1 to 3 and RS). After the R exposure using cellophane sheets during the treatment time period as mentioned for (RT1–RT3, RS), the sheets were removed, and _P. tricornutum_ culture was exposed to the full spectrum of white light. In RT1, the culture was exposed to red light for first 4 days and then exposed to white light. In RT2, the culture was exposed to white light during first 3 days; then, it was exposed to red light by wrapping the flask from the fourth to seventh day and then again exposing the flask to white light. In RT3, the culture was exposed to white light until the seventh day and after was given red light treatment. Similarly, in RS, the red light was given from the first to seventh day and then exposed to white light for 72 h before harvesting. Below, the graphical representation of the setup aligned with the growth curve.