Deploying Pseudomonas putida for the conversion of aromatic compounds from fractionated industrial hydrolysis lignin

Abstract

The world’s most abundant natural aromatic polymer is paradoxically one of its most un- derutilized feedstocks. Lignin is the pulp and paper industry’s primary by-product, and it shows great potential as a renewable and carbon-neutral source of industrially relevant chemicals. The utilization of Pseudomonas putida, a robust bacterium known to catabolize aromatic compounds natively, was explored in this study as a promising approach for lignin valorization. To this end, dry hydrolysis lignin (HL) was used as the feedstock, and various HL fractionation techniques were applied, including alkaline extraction, to obtain lignin monomers, dimers, and trimers in solution for use as a growth medium. The composition of the fractionated HL media was ascertained using a range of analytical techniques. Changes in composition during flask cultivations helped inform the selection of target genes for deletion to direct compounds in the benzoate degradation pathway towards the production of cis,cis-muconic acid, an intermediate of nylon 6,6, which finds applications in industrial components, textiles, automotive parts, and electronics.