# Enhancement of Metabolite Production in High-Altitude Microalgal Strains by Optimized C/N/P Ratio
## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Strain** & \begin{tabular}{c} **Biomass** \\ **(g/L)** \\ \end{tabular} & \begin{tabular}{c} **Productivity** \\ **(g/L\(\cdot\)d\({}^{-1}\))** \\ \end{tabular} & \begin{tabular}{c} **Carbohydrates** \\ **(\% w/w)** \\ \end{tabular} & \begin{tabular}{c} **Proteins** \\ **(\% w/w)** \\ \end{tabular} & \
\begin{tabular}{c} **Lipids** \\ **(\% w/w)** \\ \end{tabular} &
\begin{tabular}{c} **References** \\ **(\% w/w)** \\ \end{tabular} \\ \hline _Ankistrodesmus falcatus KJ671624_ & 1.74 & 0.124 & & n/a & 59.6 & [121] \\ _Auxenochlore protothecodes_ & 1.06 & 0.71 & & n/a & 43.9 & [122] \\ _Auxenochlore pyrenoidosis_ & 0.89 & & n/a & & [98] \\ (formerly Chlorella pyrenoidosis) & & & & & \\ _Botryococcus_ sp. & 0.28 & & n/a & 73 & [123] \\ _B. branuili_ & 2 & 0.133 & & n/a & 70 & [24] \\ _B. branuili LB572_ & 4.57 & 0.18 & & n/a & 64.9 & [124] \\ _Chlorella_ sp. & 0.44 & & n/a & & 55 & [123] \\ _Chlorella protothecodes_ UTEX 250 & 1.19 & & n/a & & 12.9 & [125] \\ _C. sorokiniana_ 211-32 & 1.18 & 0.039 & & n/a & 38 & [126] \\ _C. sorokiniana_ UTEX 1602 & 0.68 & & n/a & & 9 & [127] \\ _C. sorokiniana_ _UTEX 2805_ & 0.66 & n/a & 52 & n/a & & [131] \\ _C. vulgaris_ UTEX 2714 & 0.24 & n/a & 59 & n/a & & \\ _C. vulgaris_ UTEX 1803 & 3.7 & & n/a & & 60 & n/a & [95] \\ _C. vulgaris_ FSP-E & 5.51 & & 51.3 & & & [132] \\ _Chlorococcus olediaciens_ & 1.6 & & & & 20 & [97] \\ _Dundiella salina_ & n/a & 0.035 & & n/a & & 22 & [128] \\ _D. tertioleta_ & n/a & 0.044 & & n/a & & 39 & [129] \\ _D. parau_ & n/a & 0.045 & & n/a & & 39 & [129] \\ _Desmodesmus armatus_ & 1.65 & & n/a & & 53.6 & n/a & [96] \\ _Scenedesmus_ sp. ASK22 & 4.67 & & & 31.06 & & 37.1 & [130] \\ \multirow{2}{*}{_S. obliquus_} & n/a & & 10-17 & 50–56 & 12–14 & [128] \\  & 2.63 & n/a & & n/a & & [132] \\  & 0.685 & & n/a & & & 39.6 & [93] \\ \multirow{2}{*}{_S. vacuolatus_} & n/a & & & & 66 & [23] \\  & 2 & n/a & & & 4\% & [90] \\ \multirow{2}{*}{_Chlorella_ sp. UFPS019} & 0.72 & 0.036 & 48.8 & & n/a & \\  & 1.5 & 0.048 & & n/a & & 26.5 \\ \multirow{2}{*}{_Desmodesmus_ sp. UFPS021} & 0.95 & 0.038 & n/a & & 38.4 & n/a & \\  & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: List of reported algal strains with culture media optimized via design of experiments. In microalgae, carbohydrates are generally found in different concentrations depending on the species and culture conditions; however, few species can synthesize a high carbohydrate content [134]. _Perphyridium crucutum_ can accumulate carbohydrates up to 57% of its dry weight, while _Chlamydomonas_ sp. normally does not exceed 17% [135]. According to [PERSON] et al. [136], _C. vulgaris_ can accumulate between 9 and 41% of its total weight (in dry weight), while _S. obliquus_ can accumulate between 10 and 47% (in dry weight). According to [PERSON] et al. [137], in _Chlorella_ sp., nitrogen reduction in the culture medium enhanced the accumulation of carbohydrates (up to 66% \(w/w\)). Under sufficient inorganic phosphate levels, _Chlorella_ sp. FC2 IITG presented high carbohydrate content (up to 47.35% \(w/w\)), whereas under deficient conditions, the content was significantly reduced (32.21% \(w/w\)). The results obtained in this paper are in accordance with [PERSON] et al. [138], where the interaction between the carbon (low to medium content) and phosphate source (medium to high content) can effectively enhance the final concentration of carbohydrates in _Chlorella_ sp. UFPS019. In the case of lipids, a method focused on the enhancement of lipid and TAG biosynthesis through the selective deficiency of specific nutrients (such as phosphorus and nitrogen) coupled with salinity stress is the most widely used protocol [128], since N and P availability in the media will play an essential role in the synthesis of amino acids and proteins [139].