Biological Lignin Depolymerization : From enzymatic sensor towards biobased aromatics in enzymatic membrane reactor – BioLiDe

In the context of the biomass recovery, lignin is the main renewable raw material composed of aromatic units, mainly from the pulp and paper industry (50 million tonnes / year). This polymer is most often recovered in pulp mills and burned for energy production. Only 1 million tonnes reached the chemicals market. Industrial lignins have a lower aryl ether content than so-called “native” lignins due to the fractionation processes used. Their depolymerization is therefore hampered by repolymerization reactions, also called condensation, leading to low yields of monomers. The approcah proposed in the BioLiDe project, which does not use solvents or chemicals, will consist in extracting the depolymerization products by membrane filtration before repolymerization. This approach also has the advantage of shifting the equilibria in favor of lignin depolymerization. In the BioLiDe project, enzyme catalysis will be used with laccases as a sustainable means of depolymerizing lignins, especially for their mild conditions of use. The balance between the polymerization and cleavage reactions depends on many factors (pH, temperature, mediators, solvents, nature and concentrations, etc), making the approach tedious and time consuming when it is necessary to identify the optimum conditions for the depolymerization reaction directly on industrial lignins instead of model aromatic molecules. This therefore considerably increases the number of experiments (several hundred) to determine the optimum conditions for depolymerization. It is therefore necessary to develop high throughput screening tools for laccases (and more generally other lignin degradation pathways) on industrial lignins in order to rapidly detect and quantify enzymatic activity. Thus, the proposed experimental development aims at the development of a sensor which will make it possible to qualify the lignin depolymerization activity and to screen the reaction conditions aimed at optimizing the efficiency of the enzymatic depolymerization of lignin; the development of an enzymatic membrane reactor which will make it possible to extract aromatic oligomers during the enzymatic depolymerization of lignin aimed at preventing their repolymerization and at limiting the inactivation of the enzyme by accumulation of products. The experimental development of industrial lignin inks, their printing by inkjet technology and their enzymatic depolymerization will be studied to ensure the development of the sensor. Then, the enzymes chosen will be implemented in an enzyme membrane reactor which will be developed within the framework of the BioLiDe project. The consortium will be composed by specialists in matter physics/micro/nanotechnology (IEMN) and enzymatic biocatalysis/microbiology (UMRtBioEcoAgro). Zymoptiq and Firer Excellence will be the industrial partners.