Renewable diesel and jet fuel from microbial sources
The invention provides methods of manufacturing alkanes from triglyceride oils produced through fermentation of oil-bearing microbes. The processes provided herein can utilize a variety of carbohydrate feedstocks including cane bagasse, sugar beet pulp, corn stover, glycerol, corn starch, sorghum, molasses, waste glycerol, and other renewable materials. These processes further comprise hydrotreating, hydrocracking, isomerization, distillation, and other petrochemical processes for use with oil-bearing microbes and products derived therefrom to manufacture fuels. Particular embodiments include the manufacture of ASTM D975 and ASTM D1655 compliant fuels. Genetically engineered microbes provided herein can be used in the manufacture of renewable diesel and renewable jet fuel.
1. A method of cultivating a recombinant microalgal cell in a culture medium, the cell comprising an exogenous gene encoding a sucrose invertase operably linked to a promoter, the method comprising the steps of:
(a) providing the microalgae;
(b) adding sucrose to the culture medium; and
(c) cultivating the microalgae in the culture medium, wherein the invertase enzyme allows the microalgae to grow on sucrose, wherein the recombinant microalgal cell is cultivated until the cell accumulates at least 10% of its dry cell weight as lipid.
2. The method of claim 1 , wherein the microalgae is of the genus Chlorella or Prototheca.
3. The method of claim 2 , wherein the microalgae is of the species Chlorella prothecoides or Prototheca moriformis.
4. The method of claim 3 , wherein the microalgae is of the species Chlorella protothecoides.
5. The method of claim 3 , wherein the microalgae is of the species Prototheca moriformis.
6. The method of claim 1 , wherein the promoter is endogenous to Chlamydomonas, Chlorella virus, cauliflower mosaic virus, Chlorella, Prototheca , or higher plant.
7. The method of claim 1 , wherein the exogenous gene is codon optimized for expression in microalgae.
8. The method of claim 1 , wherein the expressed sucrose invertase is secreted.