CO ₂ -limitation-inducible Green Recovery of fatty acids from cyanobacterial biomass

Abstract

Using genetically modified cyanobacterial strains, we engineered a Green Recovery strategy to convert membrane lipids into fatty acids for economical and environmentally sustainable biofuel production. The Green Recovery strategy utilizes lipolytic enzymes under the control of promoters induced by CO 2 limitation. Data indicate that strains of the cyanobacterium Synechocystis sp. PCC6803 engineered for Green Recovery underwent degradation of membrane diacylglycerols upon CO 2 limitation, leading to release of fatty acids into the culture medium. Recovered fatty acid yields of 36.1 × 10 -12 mg/cell were measured in one of the engineered strains (SD239). Green Recovery can be incorporated into previously constructed fatty-acid-secretion strains, enabling fatty acid recovery from the remaining cyanobacterial biomass that will be generated during fatty acid biofuel production in photobioreactors.

Fatty acid production in genetically modified cyanobacteria

“…∥ The intracellular unsecreted FFAs were extracted by the Folch method and calculated concentrations based on final cell densities. that enables recovery of membrane lipids in the spent cyanobacterial biomass (40). The cyanobacteria-based FFAs are ready biofuel precursors, which can be converted into biodiesel by esterification or jet fuel by decarboxylation.…”

Engineering Synechococcus elongatus PCC 7942 for Continuous Growth under Diurnal Conditions

“…Cyanobacteria are being considered as a platform for the conversion of renewable solar energy to biofuels (12)(13)(14)(15). Current research supports the idea that cyanobacterial biosynthesis of fuels and industrial chemicals may be one of the most efficient approaches to reduce the need for imported petroleum and to minimize CO 2 emissions (16).…”

The AbrB2 Autorepressor, Expressed from an Atypical Promoter, Represses the Hydrogenase Operon To Regulate Hydrogen Production in Synechocystis Strain PCC6803

“…Furthermore, the availability of molecular tools for gene manipulation make cyanobacteria promising "low-cost" microbial cell factories for the carbon-neutral sustainable production of alkanes (10,41), bioplastics (1), hydrogen (2,12), and lipids (25,43), while saving arable soils for crops (50). In light of their tremendous importance, deeper investigation into the mechanisms by which cyanobacteria convey solar energy to the environment is justified.…”