Production of oil in microorganisms
View Patent ↗The invention provides methods of cultivating oil-bearing microbes using xylose alone or in combination with other depolymerized cellulosic material. Also provided are microorganisms comprising an exogenous gene encoding a polysaccharide degrading enzyme, such as a cellulase, a hemicellulase, a pectinase, or a driselase. Some methods of microbial fermentation are provided that comprise the use of xylose and depolymerized cellulosic materials for the production of oil-bearing microorgansims.
1. A microalgae comprising an exogenous gene encoding a sucrose invertase, which is expressed in the microalgae and hydrolyzes sucrose to fructose and glucose, and wherein the microalgae comprises at least 20% lipid by dry cell weight.
2. The microalgae of claim 1 , wherein the microalgae is selected from Table 1.
3. The microalgae of claim 1 that is an obligate heterotroph.
4. The microalgae of claim 1 that is a species of the genus Prototheca.
5. The microalgae of claim 4 , wherein the microalgae is selected from the group consisting of Prototheca stagnora, Prototheca portoricensis, Prototheca wickerhamii, Prototheca moriformis , and Prototheca zopfii.
6. The microalgae of claim 1 that further comprises a second exogenous gene that encodes an acyl-ACP thioesterase, which is expressed in the microalgae and thereby alters the proportions of fatty acids produced in the microalgae.
7. The microalgae of claim 6 , wherein the thioesterase is selected from the group consisting of Umbellularia californica fatty acyl-ACP thioesterase, Cinnamomum camphora fatty acyl-ACP thioesterase, Myristica fragrans fatty acyl-ACP thioesterase, Elaeis guineensis fatty acyl-ACP thioesterase, Populus tomentosa fatty acyl-ACP thioesterase, Arabidopsis thaliana fatty acyl-ACP thioesterase, Gossypium hirsutum fatty acyl-ACP thioesterase, Cuphea lanceolata fatty acyl-ACP thioesterase, Cuphea hookeriana fatty acyl-ACP thioesterase, Cuphea calophylla subsp. mesostemon fatty acyl-ACP thioesterase, Cuphea lanceolata fatty acyl-ACP thioesterase, Vitis vinifera fatty acyl-ACP thioesterase, Garcinia mangostana fatty acyl-ACP thioesterase, Brassica juncea fatty acyl-ACP thioesterase, Madhuca longifolia fatty acyl-ACP thioesterase, Brassica napus fatty acyl-ACP thioesterase, Oryza sativa (indica cultivar-group) fatty acyl-ACP thioesterase, and Oryza sativa (japonica cultivar-group) fatty acyl-ACP thioesterase.
8. The microalgae of claim 1 , wherein the gene encoding the sucrose invertase includes a secretion signal so that sucrose invertase is secreted from the microalgae thereby converting available extracellular sucrose to fructose and glucose, and wherein the microalgae is capable of transporting and utilizing the glucose and fructose so produced.
9. The microalgae of claim 8 , wherein the microalgae further comprises a second exogenous gene that encodes an acyl-ACP thioesterase, which is expressed in the microalgae.
10. The microalgae of claim 9 , wherein the proportions of fatty acids of the microalgae are altered relative to the microalgae lacking the exogenous acyl-ACP thioesterase.