Engineered Pseudomonas putida KT2440 co-utilizes galactose and glucose

Abstract

AbstractBackgroundEfficient conversion of plant biomass to commodity chemicals is an important challenge that needs to be solved to enable a sustainable bioeconomy. Deconstruction of biomass to sugars and lignin yields a wide variety of low molecular weight carbon substrates that need to be funneled to product.Pseudomonas putidaKT2440 has emerged as a potential platform for bioconversion of lignin and the other components of plant biomass. However,P. putidais unable to natively utilize several of the common sugars in hydrolysate streams, including galactose.ResultsIn this work, we integrated a De Ley–Doudoroff catabolic pathway for galactose catabolism into the chromosome ofP. putidaKT2440, using genes from several different organisms. We found that the galactonate catabolic pathway alone (DgoKAD) supported slow growth ofP. putidaon galactose. Further integration of genes to convert galactose to galactonate and to optimize the transporter expression level resulted in a growth rate of 0.371 h−1. Additionally, the best-performing strain was demonstrated to co-utilize galactose with glucose.ConclusionsWe have engineeredP. putidato catabolize galactose, which will allow future engineered strains to convert more plant biomass carbon to products of interest. Further, by demonstrating co-utilization of glucose and galactose, continuous bioconversion processes for mixed sugar streams are now possible.