## 3 Results  
### Biomass Production Based on Carbon Source and Concentration  
Glucose was the most effective carbon source for the production of _E. gracilis_ biomass and paramylon (Figure 1a). The highest biomass concentration (2.0 g L\({}^{-1}\)) and paramylon concentration (1.2 g L\({}^{-1}\)) and content (58.3%) were achieved with glucose on day 3. The biomass and paramylon concentrations observed using lactate as the carbon source were lower than those observed using glucose, but the paramylon contents were similar between the two groups. The SGR increased in the order of glucose, lactate, and ethanol, thus showing a trend similar to that observed with biomass and paramylon production (Table 2).  
The most effective concentration of glucose was 15 g L\({}^{-1}\), which showed the highest paramylon content (1.2 g L\({}^{-1}\)) (Figure 1b). Biomass productions were similar among the GL5, GL15, and GL30 groups (1.6-1.8 g L\({}^{-1}\)). The lowest biomass production was observed in the GL60 reactor. Paramylon concentration and content were highest in the GL15 group (1.2 g L\({}^{-1}\) and 68.8%, respectively), followed by the GL30, GL5, and GL60 groups. The COD consumption result showed a trend similar to that observed in biomass and paramylon production (Figure 2). The higher was the glucose concentration, the greater was the amount of TN consumed and the lower was the SGR (Table 2). The maximum biomass concentration and productivity were shown in GL15, followed by GL5, GL30, and GL60. The maximum paramylon concentration and productivity were also shown in GL15, followed by GL30, GL5, and GL60.  
\begin{table}
\begin{tabular}{l c c c c c c c c} \hline \multicolumn{2}{c}{**Carbon Source**} & \multicolumn{2}{c}{**Cell Growth**} & \multicolumn{2}{c}{**Biomass Production**} & \multicolumn{2}{c}{**Paramylon Production**} \\ \hline \multirow{2}{*}{**Type**} & **Concentration** & **Specific Cell** & **Doubling** & **Max. Titer** & **Max. Pro-** & **Max. Pro-** & **Max. Pro-** & **Max. Pro-** \\  & **(g L\({}^{-1}\))** & **Growth** & **Time** & **(g L\({}^{-1}\))** & **(g L\({}^{-1}\) d\({}^{-1}\))** & **(g L\({}^{-1}\) d\({}^{-1}\))** & **(g L\({}^{-1}\))** & **(g L\({}^{-1}\) d\({}^{-1}\))** & **(g L\({}^{-1}\) d\({}^{-1}\))** & **(\%)** \\ \hline Glucose & 5 & 0.74 & 0.93 & 1.61 & 0.41 & 0.56 & 0.15 & 35.0 \\ Glucose & 15 & 0.67 & 1.04 & 1.78 & 0.43 & 1.22 & 0.35 & 81.5 \\ Glucose & 30 & 0.56 & 1.23 & 1.56 & 0.39 & 0.78 & 0.20 & 53.1 \\ Glucose & 60 & 0.11 & 6.49 & 0.67 & 0.07 & 0.22 & n.d. & 41.7 \\ Ethanol & 15 & 0.07 & 9.65 & 0.44 & 0.22 & 0.22 & 0.08 & 37.5 \\ Lactate & 15 & 0.12 & 5.96 & 1.28 & 0.56 & 0.72 & 0.31 & 56.5 \\ \hline \end{tabular}
\end{table}
Table 2: Effect of carbon source type and concentrations on _E. gracilis_ biomass and paramylon production. Specific growth and doubling time were calculated from the average values. All the reactors were set in duplicate, and the sample analyses were performed in duplicate.  
Figure 1: Biomass and paramylon production and paramylon content on day 3 in the presence of different carbon source types (glucose, ethanol, acetate, and lactate) and different concentrations (glucose 5, 15, 30, and 60 g L\({}^{-1}\)): (**a,d**) biomass production, (**b,e**) paramylon production, and (**c,f**) paramylon contents. All analyses were performed in duplicate.