Modification of an engineered Escherichia coli by a combinatorial strategy to improve 3,4-dihydroxybutyric acid production.
Biotechnol Lett 2021;
43:2035-2043. [PMID:
34448097 DOI:
10.1007/s10529-021-03169-z]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 08/05/2021] [Indexed: 01/20/2023]
Abstract
OBJECTIVES
3,4-Dihydroxybutyric acid (3,4-DHBA) is a multifunctional C4 platform compound widely used for the synthesis of various materials, including pharmaceuticals. Although, a biosynthetic pathway for 3,4-DHBA production has been developed, its low yield still precludes large-scale use. Here, a heterologous four-step biosynthetic pathway was established in recombinant Escherichia coli (E. coli) using a combinatorial strategy.
RESULTS
Several aldehyde dehydrogenases (ALDHs) were screened, using in vitro enzyme assays, to identify suitable catalysts for the dehydrogenation of 3,4-dihydroxybutanal (3,4-DHB) to 3,4-DHBA. A pathway containing glucose dehydrogenase (BsGDH) from Bacillus subtilis, D-xylonate dehydratase (YagF) from E. coli, benzoylformate decarboxylase (PpMdlC) from Pseudomonas putida and ALDH was introduced into E. coli, generating 3.04 g/L 3,4-DHBA from D-xylose (0.190 g 3,4-DHBA/g D-xylose). Disruption of competing pathways by deleting xylA, ghrA, ghrB and adhP contributed to an 87% increase in 3,4-DHBA accumulation. Expression of a fusion construct containing PpMdlC and YagF enhanced the 3,4-DHBA titer, producing the highest titer and yield reported thus far (7.71 g/L; 0.482 g 3,4-DHBA/g D-xylose).
CONCLUSIONS
These results showed that deleting genes from competing pathways and constructing fusion proteins significantly improved the titer and yield of 3,4-DHBA in engineered E. coli.
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