## 3 Results
### The Carotenoid Profile from Different C/N, C/S Ratios and Nitrogen Sources Treatments  
Ratios of different individual carotenoids from different treatments using HPLC for separation and identification are shown in Table 5. Generally, the torulene percentage increased with increasing C/N ratios, whatever nitrogen source was used. Torulene predominance with Amm was recorded \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**T**} & \multirow{2}{*}{**C/S**} & \multirow{2}{*}{**DCW (g/L)**} & **DCW-Y** & **TL (g/L)** & **TL-Y** & **TL-RP** & **TL-SR** & **TP (mg/L)** & **TF-Y** & **Car-RP** &
\begin{tabular}{c} **Car-SR** \\ **(\%/L-d)** \\ \end{tabular} \\ \hline \multirow{4}{*}{3 d} & 254 & 6.49 \(\pm\) 0.38 \({}^{a}\) & 48.7 & 2.5 \(\pm\) 0.1 & 18.64 & 38.3 & 0.83 & 0.457 \(\pm\) 0.05 & 34.4 & 70.7 & 152.9 \\  & 166 & 6.79 \(\pm\) 0.4 & 48.1 & 2.4 \(\pm\) 0.5 & 17.28 & 35.4 & 0.81 & 0.565 \(\pm\) 0.1 & 40.3 & 83.7 & 188.5 \\  & 123 & 7.26 \(\pm\) 0.4 \({}^{a}\) & 48.9 & 2.4 \(\pm\) 0.32 & 16.34 & 33.4 & 0.81 & 0.624 \(\pm\) 0.01 \({}^{d}\) & 42.03 & 85.9 & 208.1 \\  & 98 & 7.11 \(\pm\) 0.16 & 41.8 & 2.2 \(\pm\) 0.22 & 13.2 & 31.6 & 0.75 & 0.612 \(\pm\) 0.05 \({}^{d}\) & 35.9 & 86 & 203.86 \\ \hline \multirow{4}{*}{6 d} & 254 & 9.59 \(\pm\) 0.25 \({}^{b}\) & 22.4 & 5.1 \(\pm\) 0.4 \({}^{c}\) & 19.02 & 53.4 & 0.88 & 0.528 \(\pm\) 0.3 & 5.026 & 55.1 & 23.2 \\  & 166 & 10.45 \(\pm\) 0.39 & 22.8 & 5.1 \(\pm\) 0.2 \({}^{c}\) & 16.55 & 48.85 & 0.89 & 0.807 \(\pm\) 0.08 \({}^{e}\) & 14.9 & 77.2 & 80.6 \\  & 123 & 10.74 \(\pm\)0.06 \({}^{b}\) & 25.6 & 4.8 \(\pm\) 0.18 & 17.7 & 44.98 & 0.8 & 0.865 \(\pm\) 0.01 \({}^{e}\) & 17.7 & 80.5 & 80.4 \\  & 98 & 10.91 \(\pm\) 0.56 & 22.9 & 4.5 \(\pm\) 0.18 & 13.84 & 41.68 & 0.77 & 0.875 \(\pm\) 0.01 \({}^{e}\) & 15.9 & 80.2 & 87.89 \\ \hline \multicolumn{10}{c}{CW-Y: dry cell weight yield. TL-Y: total lipid yield. TP-Y: total pigment yield. TL-RP: total lipid relative productivity (mg\({}_{\text{pigment}}\)/100 \({}_{\text{glucose}}\)). Car-RP: carotenoid relative productivity (mg\({}_{\text{pigment}}\)/100 \({}_{\text{glucose}}\)). TL-SR: total lipid synthesis rate. Car-SR: carotenoid synthesis rate. d: days. The data are the mean of three repeat tests, and the standard deviation represents \(\pm\) SD. The significance of the C/S ratio on DCW, TL, and TP after three and six days were detected by using a one-way ANOVA test in SPSS. \(a\) represents each of the DCW-3d significant differences with DCW-98-3d (\(p<0.05\)). \(b\) represents each of the DCW-6d significant differences with DCW-98-6d (\(p<0.01\)). \(c\) represents each of the TL-6d significant differences with TL-98-6d (\(p<0.05\)). \(d\) represents each of the TP-3d significant differences with TL-254-3d (\(p<0.01\)). \(c\) represents each of the TP-6d significant differences with TL-254-6d (\(p<0.05\)).  
\end{table} 
Table 4: Effect of different C/S ratios on dry cell weight (DCW), lipid (TL), and carotenoid (TP) produced by _R. glutinis_ after three days and six days. Figure 2: Microscopic examination of yeast cells stained with Nile red fluorescence dye. Yeast cells were grown in a shaken flask under different C/S ratios and a C/N equal to 146, using ammonium sulfate and yeast extract as a nitrogen source for six days. The C/S ratios used were: (**a**) 254, (**b**) 166, (**c**) 123, and (**d**) 98. The magnification bar is equal to 10 μm. around 62%, followed by 57.3% with PEP, while yeast extract showed the highest \(\gamma\)-carotene ratio (52.3%) at C/N ratio 70. Similarly, when different C/N ratios were affected on _Rhodotorula glutinis_, torularhodin and torulene was the dominant carotenoid in all C/N ratios treatments, but the highest \(\beta\)-carotene was observed with low C/N ratio [12]. In another study, the maximum production of \(\beta\)-carotene occurred when _R. glutinis_ was grown in a medium with a low C/N ratio containing a high concentration of both carbon (glycerol, 80 g/L) and nitrogen [51].