Ligninolytic Enzymes: Keys to unlock the hidden potential of lignin

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Context: Globally, 50-70 million tons of lignin, a highly branched heteroaromatic polymer, are discharged per year as a waste material from the paper and pulp industry despite being touted as the most abundant renewable source of different value-added products on earth. Leaving 98% of lignin underutilized, industries degrade only 2% of lignin and that also comes with environmentally hazardous thermochemical processes. Background: Recently, the discovery of heme-containing class II fungal peroxidases viz. lignin peroxidase (LiP), manganese peroxidase (MnP), versatile peroxidase (VP), dye-decolorizing peroxidase (DyP) garnered a lot of attention due to their biodegradable ligninolysis. However, the industrial application of peroxidase-based lignin degradation still seems to be a far-flung dream owing to low availability of peroxidases in sufficient amount, enzyme instability in industrial effluent, high enzyme cost and long process times. Aims and objective: I hypothesize that a cocktail of engineered stress tolerant, active and stable peroxidases could lead to synergistic biodegradation of lignin. To achieve this, artificial intelligence (AI) tailored LiP, MnP, VP and DyP will be cloned and expressed as inclusion bodies (IBs) in E. coli using Prof. Spadiut’s expertise whereas mine will employ solubilization and refolding strategies to increase the overall yield of bioactive protein. An ideal stoichiometric combination of engineered peroxidases will be standardized to withstand the harsh conditions of industrial effluent, resulting in a sustainable and economic ligninolytic technology. Concluding remarks: The project is inspired from nature, backed with AI and stemmed with the expertise of mine and Prof. Spadiut’s in producing recombinant bioactive protein from bacterial IBs while TU Wien’s decades of experience in commercializing the technology will be a fertile playground to bow the seeds of a sustainable ligninolytic technology.