## 3 Results
### Growth of Leptolyngbya sp. KIOST-1 under Different Environmental Regimes  
Based on the high protein content and the C-phycocyanin, chlorophyll-a, and biomass concentration in culture medium #11, the SOT medium of _Leptolyngbya_ sp. KIOST-1, we examined the effects of different carbon and nitrogen concentrations on the culture environment.  
Figure 6a shows the effect of culturing in 10 different concentrations of sodium bicarbonate as the carbon source, ranging from 0 to 42 g L\({}^{-1}\). The growth of _Leptolyngbya_ sp. KIOST-1 cultured in the presence of the most commonly used bicarbonate concentration (that is, 16.8 g L\({}^{-1}\) in the regular SOT medium) reached a biomass concentration of 1.96 \(\pm\) 0.01 g L\({}^{-1}\) on the final day of culture. _Leptolyngbya_ sp. KIOST-1 cells cultured in media containing sodium bicarbonate at concentrations ranging from 10.08-42 g L\({}^{-1}\) displayed no significant differences in growth between any of the conditions by the final day. Media with lower levels of carbon (that is, 3.36 and 6.72 g L\({}^{-1}\) bicarbonate) led to cell death from days 8 and 12, respectively (\(p<0.05\)). The complete limitation of sodium bicarbonate significantly inhibited the growth of _Leptolyngbya_ sp. KIOST-1. Figure 6b shows the effect of culturing in 10 different concentrations of sodium nitrate, ranging from 0 to 6.25 g L\({}^{-1}\). The concentration of sodium nitrate in the regular SOT medium was 2.5 g L\({}^{-1}\). The lowest biomass concentration was 0.96 \(\pm\) 0.01 g L\({}^{-1}\) under nitrogen-limited conditions on the final day, which was significantly different from that observed on day 4. Microscopic observations revealed fewer filamentous hormogonia and fewer cells under nitrogen-limited conditions than in regular SOT medium (Figure 6b). Except under nitrogen-limited conditions, there were no significant differences in growth.  
The SOT medium had a salinity level of 12.0 \(\pm\) 0.2 psu. Figure 7a shows the effects of different degrees of salinity on growth. On the final day, there were no significant differences in the growth in other culture media at 50 psu. However, at 80 psu, _Leptolyngbya_ sp. KIOST-1 cells did not display any signs of growth.  
The effect of pH on _Leptolyngbya_ sp. KIOST-1 cells is shown in Figure 7b. The pH of the SOT medium was 9.3 and was set as the median value for the experiment. There were no significant differences in the growth of cells cultured at different pH values.  
\begin{table}
\begin{tabular}{l l l} \hline  & **1 st Trial** & **2 nd Trial** \\ \hline Culture period (days) & 13 & 13 \\ Final biomass production (g L\({}^{-1}\)) & 1.21 \(\pm\) 0.12 & 1.01 \(\pm\) 0.08 \\ Proximate composition (\%) & & \\ \hline Protein & 66.15 \(\pm\) 0.30 & 67.38 \(\pm\) 0.58 \\ Lipid & 12.82 \(\pm\) 0.18 & 11.98 \(\pm\) 0.32 \\ Carbohydrate & 7.69 \(\pm\) 1.21 & 9.19 \(\pm\) 0.83 \\ Moisture & 2.45 \(\pm\) 0.48 & 2.12 \(\pm\) 0.06 \\ Ash & 10.89 \(\pm\) 1.21 & 9.33 \(\pm\) 0.12 \\ Photosynthetic pigments (mg g\({}^{-1}\)) & & \\ \hline C-phycocyanin & 28.88 \(\pm\) 0.69 \({}^{\text{a}}\) & 22.87 \(\pm\) 0.02 \({}^{\text{b}}\) \\ Allo-phycocyanin & 17.59 \(\pm\) 2.83 & 8.91 \(\pm\) 3.28 \\ Phycoerythrin & 8.07 \(\pm\) 0.96 \({}^{\text{a}}\) & 3.03 \(\pm\) 0.85 \({}^{\text{b}}\) \\ Chlorophyll-a & 6.85 \(\pm\) 0.51 & 5.62 \(\pm\) 0.31 \\ \hline \end{tabular}
\end{table}
Table 2: Proximate and phytochemical pigment compositions of _Leptolyngbya_ sp. KIOST-1 cells cultured in open raceway pond (mean \(\pm\) standard error, \(n=3\)). Significant differences are represented using different lowercase letters as determined by two-tailed Student’s \(t\)-test, \(p<0.05\).