Improving ethylene glycol utilization in Escherichia coli fermentation

Ethylene glycol (EG) is used in the manufacture of polyester plastics such as polyethylene terephthalate (PET). EG has a potential to become an abundant, renewable substrate in the future to fuel microbial production of value-added chemicals. It could be obtained from hydrolysis of the plastic wastes, or hydrogenolysis of cellulosic wastes. Escherichia coli is a workhorse in metabolic engineering applications, but most E. coli strains are unable to metabolize EG. In this study, we have successfully engineered E. coli to grow on EG as the major carbon source by overexpressing two dehydrogenases (FucO and AldA) that oxidize EG into glycolate, which can be metabolized via the glycerate pathway. Overexpression of fucO and aldA with a constitutive promoter (P_gyrA) improved the cell growth on EG. EG utilization was further improved with the supplementation of a mixture of amino acids at low concentration. In an optimized medium, the engineered strain consumed up to 20 g/L of EG. With further development in the future, this strain can potentially produce valuable chemicals from raw EG derived from plastic and cellulosic waste streams.

Automated summary

This study successfully engineered E. coli to grow on ethylene glycol as the major carbon source by overexpressing two dehydrogenases, improving cell growth on EG through overexpression of fucO and aldA with a constitutive promoter and supplementing a mixture of amino acids at low concentration. With further development, this strain has the potential to produce valuable chemicals from raw EG derived from plastic and cellulosic waste streams.