Production of 3-hydroxypropionic acid from glycerol by a novel recombinant Escherichia coli BL21 strain

Abstract

3-Hydroxypropionic acid (3-HP) is an important platform chemical from which several commodity and specialty chemicals can be generated. The present investigation focuses on the construction and evaluation of a recombinant strain Escherichia coli SH254 that produces 3-HP from glycerol. The strain was developed by cloning two genes, dhaB of Klebsiella pneumoniae DSM 2026 encoding glycerol dehydratase and aldH of E. coli K-12 MG1655 encoding aldehyde dehydrogenase, respectively. In vitro assays of crude enzyme extract of glycerol dehydratase (DhaB) showed 37.0 U mg −1 protein on glycerol with coenzyme B 12, and partially purified aldehyde dehydrogenase (AldH) exhibited 22.8 U mg −1 protein on 3-hydroxypropionaldehyde (3-HPA) with NAD + as a cofactor. When cultivated aerobically on a glycerol medium containing yeast extract, the recombinant E. coli SH254 produced 3-HP at a maximum of 6.5 mmol l −1 (0.58 g l −1). The highest specific rate and yield of 3-HP production were estimated as 6.6 mmol g −1 cdw h −1 and 0.48 mol mol −1 glycerol, respectively. Although not optimized extensively, this study is encouraging for further development of a bioprocess to produce 3-HP from glycerol.