## 2 Glycerol-Based Biomanufacturing Using _Yarrowia_
### Bioconversion of Glycerol to Various Bio-Products
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Strain** &
\begin{tabular}{c} **Carbon** \\ **Source 1** \\ \end{tabular} & **Product** & **Engineering 2** & **Strategy** & **Set-Up 3** & **Data from [Ref.]** \\ \hline \multirow{2}{*}{LGAM S(7)1} & \multirow{2}{*}{CG} & \multirow{2}{*}{35 g L\({}^{-1}\) citric acid} & \multirow{2}{*}{ME} & High C/N media; & \multirow{2}{*}{SF} & \multirow{2}{*}{[65]} \\  & & & & & pH \(\geq\) 5.0 & \\ \hline \multirow{4}{*}{A101} & \multirow{4}{*}{CG} & \multirow{4}{*}{CG} & 75.9 g L\({}^{-1}\) & \multirow{4}{*}{SE; ME} & Co-overexpression of & \multirow{4}{*}{B} & \multirow{4}{*}{[67]} \\  & & 42.5 g L\({}^{-1}\) isocitric acid & & & & pH 3.0 \\ \hline \multirow{4}{*}{ACA-YC 5031} & \multirow{4}{*}{CG} & 54.0 g L\({}^{-1}\) citric acid; & \multirow{4}{*}{ME} & Addition of phenolic & \multirow{4}{*}{SF} & \multirow{4}{*}{[68]} \\  & & secondary & & & NaCl concentrations; & pH 5.0–6.0 \\ \hline \multirow{4}{*}{NG40/UV7} & \multirow{4}{*}{CG} & \multirow{4}{*}{112.0 g L\({}^{-1}\) citric acid} & \multirow{4}{*}{ME; PE} & Addition of inorganic & \multirow{4}{*}{B} & \multirow{4}{*}{[69]} \\  & & & & nutrients (nitrogen, & & phosphorus, or sulfur); & \\ \cline{1-1} \cline{5-5}  & & & & pulsed addition of & & \\ \cline{1-1} \cline{5-5}  & & & & glycerol; pH 5.0 & & \\ \hline \multirow{4}{*}{Wratislavia AWG7} & \multirow{4}{*}{CG} & \multirow{4}{*}{157.5 g L\({}^{-1}\) citric acid} & \multirow{4}{*}{SE; PE} & Acetate negative & \multirow{4}{*}{B} & \multirow{4}{*}{[70]} \\  & & & & mutants; glycerol & & \\ \cline{1-1} \cline{5-5}  & & & concentration; pulsed & & & \\ \cline{1-1} \cline{5-5}  & & & addition or constant & & & \\ \cline{1-1} \cline{5-5}  & & & feeding rate; pH 5.5 & & & \\ \hline \multirow{4}{*}{A-101-1.22} & \multirow{4}{*}{CG} & \multirow{4}{*}{112.0 g L\({}^{-1}\) citric acid} & \multirow{4}{*}{SE; PE} & Acetate negative & \multirow{4}{*}{B} & \multirow{4}{*}{[71]} \\  & & & mutants; batch, & & repeated batch, cell & \\ \cline{1-1} \cline{5-5}  & & & recycle regimes; pH 5.5 & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Engineering strategies (strain, medium, process) and cultivation systems using pure or crude glycerol as carbon source for the production of citric acid by _Y. lipolytica_. The efficient assimilation of glycerol by _Y. lipolytica_ was also demonstrated for the production of erythroid, a sugar alcohol used as a low-calorie sweetener. [PERSON] et al., used pure and crude glycerol for citric acid and erythroid biosynthesis using wild type and acetate negative mutants in fermentations with varying pH values (3.0-6.5). They observed that lower pH inhibited citric acid and simultaneously enhanced erythroid formation, while, interestingly, the addition of NaCl to the medium as well as the use of crude glycerol (containing salt) also enhanced erythroid production. They stated that the activity of enzymes involved in erythroid biosynthesis (i.e., enzymes of PPP, transketolase and erythrose reductase) was increased by low pH and NaCl presence in the medium [74]. In a recent study, 13 species belonging to the _Yarrowia_ clade were isolated from different biotic and abiotic environments (e.g., food, seawater, termite intestine) and tested for erythroid, mannitol and arabid production using crude glycerol from the biodiesel and soap industries. _Yarrowia divalgata_ and _Candida solancensis_ turned out to be particularly efficient polyol producers, producing large amounts from both soap-derived glycerol (59.8-62.7 g L\({}^{-1}\)) and biodiesel-derived glycerol (76.8-79.5 g L\({}^{-1}\)). It is equally important that the protein and lipid contents of their biomass (around 30% and 12%, respectively) were also high enough to be considered suitable for animal feed [75]. Medium engineering, examining various parameters affecting erythroid production from glycerol by _Y.