Metabolic engineering of Escherichia coli for the efficient production of 5-hydroxyvaleric acid

Abstract

There is increasing industrial demand for five-carbon platform chemicals, particularly 5-hydroxyvaleric acid (5-HV), a widely used building block for the synthesis of polyesters and polyurethanes. Here, we developed an efficient 5-HV microbial producer by systems metabolic engineering of Escherichia coli W3110. To derive 5-HV, Pseudomonas putidal-lysine monooxygenase (davB) and 5-aminovaleramide amidohydrolase (davA), E. coli 4-aminobutyrate aminotransferase (gabT), and different aldehyde reductase genes were introduced to E. coli W3110 to convert l-lysine hydrochloride to the target product. Three aldehyde reductases, including YajO from P. putida and YahK and YqhD from E. coli, were examined, revealing that the overexpression of aldehyde reductases was critical for 5-HV production and YajO was first reported for efficient production of 5-HV. The E. coli 5-aminovalerate exporter encoded by gabP and E. coli lysine-specific permease encoded by lysP were expressed to further enhance 5-HV production. In addition, a hok/sok toxin/antitoxin system based on the E. coli XL1-Blue genome was inserted to the dual-vector system to decrease plasmid loss. Finally, 5.59 g/L of 5-HV with a yield of 0.96 mol/mol (5-HV/l-lysine hydrochloride) by shake flask cultivation of the engineered E. coli W3110 and 35.6 g/L of 5-HV with a yield of 0.92 mol/mol (5-HV/l-lysine hydrochloride) by fed fermentation were achieved respectively. The developed metabolic engineering strategies provide a basis for the efficient and sustainable bio-based production of 5-HV.