# Biosynthesis of Edible Terpenoids: Hosts and Applications
## 2 Microbial Chassis as Cell Factories for Edible Terpenoids
### Eukaryotic microorganisms
#### 2.2.1 S. cerevisiae
\begin{table}
\begin{tabular}{c c c c c} \hline
**Organism** & **Chemicals** & & **Strategy** & **Yield** & **Reference** \\ \hline
\begin{tabular}{c} _Rhodosporidium_ \\ _toraloides_ \\ \end{tabular} & Astaxanthin & (1) & Using gamma irradiation mutagenesis to obtain a strain with a high yield of & 1.26 mg/L & [67] \\  & & (2) & Using response surface methodology to optimize the large-scale culture conditions. & \\ \hline \multirow{8}{*}{Limonene} & (1) & Using carotenoid-deficient _R. turaloids_ as the host to block competing pathways; & \\  & & (2) & Increasing the flux of MVA pathway; & \\  & & (3) & Introducing an orthogonal immense synthesis pathway based on _n_eryl pyrophosphate synthase and limonene synthase & 393.5 mg/L & [68] \\  & & (NPP) by fusion expressing _n_eryl pyrophosphate synthase and limonene synthase & & \\  & & SiNPPSI-CHLS1. & & \\ \hline \multirow{8}{*}{Limonene} & (1) & Verifying the peroxisal targeting signals (PTSs) via fluorescence microscopy & \\  & & analysis; & & \\  & & (2) & Targeting MVA and limonene biosynthetic pathways to peroxis; & \\  & & (3) & Dual metabolic regulation of the synthetic pathway in the cytoplasm and peroxisome. & \\ \hline \multirow{8}{*}{ent-Kaurene} & (1) & Selected ent-kaurene synthase from _Ghberalda fridivivivi_ (G/KS); & \\  & & (2) & Balancing the expression level of GGPP synthase (GGPPS) and KS; & \\  & & (3) & Scaling up the cultivation to a 2 L bioreactor in a medium containing 75\% corn stover hydrolysate. & 1.4 g/L & [70] \\ \hline \multirow{8}{*}{Amorphadiene Bisabolene} & (1) & Expressing the codon-optimized bisabolene synthase (ABS); & 36 mg/L & \\  & & synthase (ADS); & 680 mg/L & [71] \\  & & Testing different carbon sources. & & \\ \hline \multirow{8}{*}{\(\alpha\)-Bisabolene 1,8-Cineode} & (1) & Integrating a second BS expression cassette; & \\  & & (2) & Transcriptions and proteomics analysis in the \(\alpha\)-bisabolene producing strains; & \\ \cline{1-1}  & & (3) & Balancing the expression levels of the two terminal enzymes: GPPS and 1,8-cineole & 2.6 g/L & \\ \cline{1-1}  & & synthase to synthesize 1,8-cineole; & 1.4 g/L & \\ \cline{1-1}  & & (4) & Regulating MVA pathway; & \\ \cline{1-1}  & & Optimizing the medium and fermentation process. & \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._phosphorylation of isoprenol or preenol (Figure 2a) [76]. It was reported that the advantage of the IUP is its minimal cofactor requirement, where only two molecules of ATP are needed to synthesize one molecule of IPP. However, it was found that isoprenol in the IUP pathway inhibits the respiration of _S. cerevisiae_. In order to overcome this problem, [PERSON] et al. designed an IU pathway-dependent (IUPD) strain with growth-coupled production. By utilizing the auxotroph phenotype towards isoprenol, they developed a growth-coupled high-throughput screening method and identified two kinase mutants with higher activity, _Sm_DAGK\({}^{\text{S47A}/\text{L124A}}\) and _At_IPK\({}^{\text{S207P/A272R}}\). The resultant strains with strengthened IUP pathways had higher fluxes of IPP/DMAPP, producing more squalene, limonene, and carotenoids [77].