TABLE 2.
Comparison of reported ALK production titers in yeast.
| Host | ALK pathway enzymes | Remarks | ALK titer (mg/L)a | References |
| Saccharomyces cerevisiae | Engineered FACR and cADO | Wild-type S. cerevisiae | 1.496 | This work |
| Engineered FACR and cADO | Four ADHs were deleted. Fatty acyl-CoA biosynthesis was upregulated by deleting OPI1. | 1.54 | ||
| S. cerevisiae | Cyanobacterial FAAR and cADO | HFD1 aldehyde dehydrogenase gene was deleted. | 0.14 | Zhou et al., 2016b |
| CAR and cADO | POX1 was deleted to inactivate beta-oxidation. HFD1 and ADH5 were deleted to inactivate competing pathways. | 0.8 | ||
| S. cerevisiae | Cyanobacterial FAAR and cADO | Cytosolic ALK pathway in wild-type S. cerevisiae. | 0.035 | Zhou et al., 2016a |
| CAR and cADO | Cytosolic ALK pathway in wild-type S. cerevisiae. | 0.06 | ||
| CAR and cADO | Cytosolic ALK pathway. POX1 was deleted to inactivate beta-oxidation. HFD1, ADH5, and SFA1 were deleted to inactivate competing pathways. | 0.7 | ||
| CAR and cADO | Peroxisomal ALK pathway. POX1 was deleted to inactivate beta-oxidation. HFD1 was deleted to inactivate competing pathway. | 1.2 | ||
| CAR and cADO | Peroxisomal ALK pathway. POX1 was deleted to inactivate beta-oxidation. HFD1 was deleted to inactivate competing pathway. Peroxisome biogenesis was increased by deleting PEX31–32 and overexpressing PEX34. | 3.55 | ||
| S. cerevisiae | DOX and cADO | FAA1 and FAA4 were deleted to accumulate FFAs. | 0.074 | Foo et al., 2017 |
| Yarrowia lipolytica | Bacterial FACR and cADO | Cytosolic ALK pathway in an oleaginous yeast host. | 3.2 | Xu et al., 2016 |
| Bacterial FACR and cADO | The ALK pathway was targeted to the endoplasmic reticulum of the oleaginous yeast. | 16.8 | ||
| CAR and cADO | Cytosolic ALK pathway in an oleaginous yeast host. | 23.3 | ||
| S. cerevisiae | Fatty acid decarboxylase, UndA | The host was engineered to produce medium-chain fatty acids and inactivate the beta-oxidation pathway. The highest titer was achieved with 20 g/L of glucose. | 3.35 | Zhu et al., 2017 |
| S. cerevisiae | Fatty acid decarboxylase, OleT | FAA1 and FAA4 were deleted to accumulate FFAs. HEM3 was overexpressed to increase the heme co-factor. CCP1 was deleted to accumulate H2O2. The highest titer was achieved upon gene expression tuning and bioreactor process optimization. | 3.7 | Chen et al., 2015 |
ALK, alkane and alkene; FACR, fatty acyl-CoA reductase; FAAR, fatty acyl-(acyl-carrier-protein) reductase; cADO, cyanobacterial aldehyde deformylating oxygenase; FFA, free fatty acid.aTiters of fatty acyl-CoA-dependent ALK pathway are shown in bold. Otherwise, the titers were from FFA-dependent ALK pathways.