Dual Valorization of Lignin as a Versatile and Renewable Matrix for Enzyme Immobilization and (Flow) Bioprocess Engineering.

Ana I Benítez‐Mateos,Stefania Bertella,Francesca Paradisi,Jeremy S Luterbacher,Jean Behaghel De Bueren

doi:10.1002/cssc.202100926

Ana I Benítez‐Mateos, Stefania Bertella + Show 3 more

Open Access

https://doi.org/10.1002/cssc.202100926

Copy DOI

Abstract

Lignin has emerged as an attractive alternative in the search for more eco‐friendly and less costly materials for enzyme immobilization. In this work, the terephthalic aldehyde‐stabilization of lignin is carried out during its extraction to develop a series of functionalized lignins with a range of reactive groups (epoxy, amine, aldehyde, metal chelates). This expands the immobilization to a pool of enzymes (carboxylase, dehydrogenase, transaminase) by different binding chemistries, affording immobilization yields of 64–100 %. As a proof of concept, a ω‐transaminase reversibly immobilized on polyethyleneimine‐lignin is integrated in a packed‐bed reactor. The stability of the immobilized biocatalyst is tested in continuous‐flow deamination reactions and maintains the same conversion for 100 cycles. These results outperform previous stability tests carried out with the enzyme covalently immobilized on methacrylic resins, with the advantage that the reversibility of the immobilized enzyme allows recycling and reuse of lignin beyond the enzyme inactivation. Additionally, an in‐line system also based on lignin is added into the downstream process to separate the reaction products by catch‐and‐release. These results demonstrate a fully closed‐loop sustainable flow‐biocatalytic system based exclusively on lignin.

Highlights

As society searches for more eco-friendly technologies, both science and industry are increasingly focusing on the beneficial properties of lignin, a major component of lignocellulosic biomass, which has been traditionally relegated to being an unutilized by-product.[1]
Following a recently developed protocol for the simultaneous extraction and functionalization of lignin with terephthalic aldehyde (TALD),[14] we performed fractionation of lignocellulosic biomass in presence of an increasing concentration of TALD to extract lignins functionalized with 1.5 mmol gÀ 1 of aldehyde groups (Figure 1 and Figure S1 in the Supporting Information)
We have exploited for first time the application of functionalized lignins and an oligomeric fraction, obtaining a flow system fully based on lignin as a matrix

Summary

Introduction

Agriculture as a fertilizer and in animal feed,[5] in the construction industry as emulsifying and dispersing agent,[6] and in the food industry[1] among others. A new fractionation strategy was reported that used aldehyde as protecting groups to stabilize the lignin β-O-4 bonds through formation of stable acetals, which prevents this recondensation and preserves a native-like lignin structure.[12,13] this process allows to obtain an uncondensed lignin that can be converted to small aromatic units in neartheoretical yields and an additional oligomeric and aromatic fraction after catalytic hydrogenolysis. G., product separation) is limited to commercially available materials In this context, developing a more selective and universal method for immobilizing enzymes could greatly expand the use of this sustainable substrate in biocatalysis. Lignin was used as a scavenger material for downstream processes in flow, resulting in a fully sustainable closed-loop biosynthetic process

Results and Discussion

Conclusion

Conflict of Interest