Enhanced production of trans-cinnamic acid in Photorhabdus luminescens with homolog expression and deletion strategies.

Abstract

This study aimed to overproduce industrially relevant and safe bio-compound trans-cinnamic acid (tCA) from Photorhabdus luminescens with deletion strategies and homologous expression strategies that had not been applied before for tCA production. The overproduction of the industrially relevant compound tCA was successfully performed in P. luminescens by deleting stlB (TTO1ΔstlB) encoding a cinnamic acid CoA ligase in the isopropylstilbene pathway and the hcaE insertion (knockout) mutation (hcaE::cat) in the phenylpropionate catabolic pathway, responsible for tCA degradation. A double mutant of both stlB deletion and hcaE insertion mutation (TTO1DM ΔstlB-hcaE::cat) was also generated. These deletion strategies and the phenylalanine ammonium lyase-producing (PI-PAL from Photorhabdus luminescens) plasmid, pBAD30C, carrying stlA (homologous expression mutants) are utilized together in the same strain using different media, a variety of cultivation conditions, and efficient anion exchange resin (Amberlite IRA402) for enhanced tCA synthesis. At the end of the 120-h shake flask cultivation, the maximum tCA production was recorded as 1281mg l-1 in the TTO1pBAD30C mutant cultivated in TB medium, with the IRA402 resin keeping 793mg l-1 and the remaining 488mg l-1 found in the supernatant. TCA production was successfully achieved with homologous expression, coupled with deletion and insertion strategies. 1281mg l-1is the highest tCA concentration that achieved by bacterial tCA production in flask cultivation, according to our knowledge.