Microbial Phenol Production in Metabolically Engineered E. coli Using Synthetic sRNA Technology

Abstract

Microbial phenol production has been challenged by low metabolic fluxthrough the biosynthetic pathway of aromatic compounds and microbialtoxicity of phenol. To overcome these hurdles, we metabolicallyengineered 18 Escherichia coli strains to enforce the metabolic flux towardthe immediate precursor, L-tyrosine, using the synthetic sRNA technologyfor target gene knockdown and developed a biphasic fermentation strategyto minimize the effects of phenol on cell growth. E. coli strainsoverexpressing Pasteurella multocida tyrosine phenol-lyase with tyrR andcsrA downregulated using sRNA efficiently produced phenol from glucose.Among the strains tested, an engineered BL21(DE3) strain showed ahighest phenol titer of 419 mg/L in flask culture and 1.69 g/L in fed-batchfermentation. The titer was increased up to 3.79g/L in biphasic fed-batchfermentation. [This work was supported by the Intelligent SyntheticBiology Center through the Global Frontier Project of the Ministry of Science, ICT & Future Planning through the NationalResearch Foundation of Korea.]