Production of acrylic acid and propionic acid by constructing a portion of the 3-hydroxypropionate/4-hydroxybutyrate cycle from <i>Metallosphaera sedula</i> in <i>Escherichia coli</i>

Abstract Acrylic acid and propionic acid are important chemicals requiring affordable, renewable production solutions. Here, we metabolically engineered Escherichia coli with genes encoding components of the 3-hydroxypropionate/4-hydroxybutyrate cycle from Metallosphaera sedula for conversion of glucose to acrylic and propionic acids. To construct an acrylic acid-producing pathway in E. coli, heterologous expression of malonyl-CoA reductase (MCR), malonate semialdehyde reductase (MSR), 3-hydroxypropionyl-CoA synthetase (3HPCS), and 3-hydroxypropionyl-CoA dehydratase (3HPCD) from M. sedula was accompanied by overexpression of succinyl-CoA synthetase (SCS) from E. coli. The engineered strain produced 13.28 ± 0.12 mg/L of acrylic acid. To construct a propionic acid-producing pathway, the same five genes were expressed, with the addition of M. sedula acryloyl-CoA reductase (ACR). The engineered strain produced 1430 ± 30 mg/L of propionic acid. This approach can be expanded to synthesize many important organic chemicals, creating new opportunities for the production of chemicals by carbon dioxide fixation.