Metabolic engineering of fatty acyl-ACP reductase-dependent pathway to improve fatty alcohol production in Escherichia coli

Fatty alcohols are important components of surfactants and cosmetic products. The production of fatty alcohols from sustainable resources using microbial fermentation could reduce dependence on fossil fuels and greenhouse gas emission. However, the industrialization of this process has been hampered by the current low yield and productivity of this synthetic pathway. As a result of metabolic engineering strategies, an Escherichia coli mutant containing Synechococcus elongatus fatty acyl-ACP reductase showed improved yield and productivity. Proteomics analysis and in vitro enzymatic assays showed that endogenous E. coli AdhP is a major contributor to the reduction of fatty aldehydes to fatty alcohols. Both in vitro and in vivo results clearly demonstrated that the activity and expression level of fatty acyl-CoA/ACP reductase is the rate-limiting step in the current protocol. In 2.5-L fed-batch fermentation with glycerol as the only carbon source, the most productive E. coli mutant produced 0.75 g/L fatty alcohols (0.02 g fatty alcohol/g glycerol) with a productivity of up to 0.06 g/L/h. This investigation establishes a promising synthetic pathway for industrial microbial production of fatty alcohols.