Metabolic engineering of Escherichia coli for the production of phenol and anthranilic acid

Abstract

Since the majority of aromatic chemicals are currently manufactured employing petroleum as the raw material, development of alternate sustainable production methods have been a driving force. In this study, Escherichia coli was metabolically engineered for the production of phenol and anthranilic acid. For phenol production, I examined 18 E. coli strains with respect to their precursor production, product tolerance, and enzyme activity in search for the host strain for phenol production by introducing tyrosine phenol-lyase(tpl). Among the strains, engineering E. coli BL21 showed the highest phenol tier in flask culture and produced 1.69 g/L of phenol in fed-batch cultures. To solve the toxicity problem, two-phase extractive fermentation was performed and then produced 5.62 g/L of phenol finally.

W3110trpD9923 which revealed a nonsense mutation in the trpD gene, showed the probability to accumulate anthranilic acid by the loss of anthranilic acid phosphoribosyl transferase activity, but maintain anthranilic acid synthase activity. The effects of expressing genes of $aroG^{fbr}$, tktA, ppsA, aroK and aroC were evaluated. In shake flask experiments with minimal medium, strains W3110trpD9923/pAnt-G and W3110trpD9923/pAnt2 displayed the best production parameters, accumulating 1.07 - 1.13 g/L of anthranilic acid.