Muconic Acid Production Using Engineered Pseudomonas putida KT2440 and a Guaiacol-Rich Fraction Derived from Kraft Lignin

Henrik Almqvist,Henrique Veras,Javier Garcia Hidalgo,Magnus Carlquist,Christian Hulteberg,Kena Li,Marie Gorwa-Grauslund,Nádia Skorupa Parachin

doi:10.1021/acssuschemeng.1c00933

Henrik Almqvist, Henrique Veras + Show 6 more

Open Access

https://doi.org/10.1021/acssuschemeng.1c00933

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Abstract

Industrial lignin such as kraft lignin is an abundant feedstock for renewable chemicals and materials. In this study, a process was developed for depolymerization of kraft lignin followed by an upgrading separation step and further bioconversion of the obtained monoaromatic compounds to muconic acid. First, industrial kraft lignin, Indulin AT, was processed into a guaiacol-rich stream using base-catalyzed depolymerization. This stream was subsequently upgraded using liquid–liquid extraction and evaporation to yield a more concentrated and less inhibitory stream, adapted for bioconversion. Finally, guaiacol was quantitatively converted to muconic acid through bioconversion using an engineered Pseudomonas putida strain containing cytochrome P450 and ferredoxin reductase for guaiacol assimilation and deletion of the native catBC genes for muconic acid production. Isomerization of muconic acid in a fermentation medium depending on pH was also studied.

Highlights

Kraft lignin is an abundant source of renewable carbon stemming from the kraft pulping process, through which 95% of all chemical pulp is made.[1]
Indulin AT is an industrial pine softwood lignin that is precipitated from black liquor of linerboard-grade pulp and has previously been found to be a rich source of guaiacol.[7]
A process was developed for depolymerizing kraft lignin into guaiacol, which is a useful monomer for microbial conversion to muconic acid

Summary

Introduction

Kraft lignin is an abundant source of renewable carbon stemming from the kraft pulping process, through which 95% of all chemical pulp is made.[1]. As recovery of the cooking chemicals from lignin is one of the most costly processes in kraft pulping, separating its parts lowers the recovery boiler load It enables the valorization of the kraft lignin stream, which would benefit the process economy.[3] One method of facilitating valorization of lignin is to depolymerize it into smaller molecules for use as fuels or chemicals.[4] depolymerized technical lignin (DTL) is typically composed of a relatively dilute and heterogeneous mix of compounds, which are challenging to separate and process further. These methods may be transferred to microbial valorization schemes as well

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