Dismantling darkness: interdisciplinary perspectives on melanin degradation

Abstract

Microbial melanins are exceptionally recalcitrant biopolymers that facilitate fungal virulence and biodeterioration. This review synthesizes physical, chemical, and biological degradation strategies for major microbial melanin categories, aligning technical mechanisms with their translational potential. While physical methods such as ultrasound-assisted (UAE) and microwave-assisted extraction (MAE) function as matrix-disrupting pretreatments rather than standalone degradation strategies, chemical approaches remain the analytical standard for structural fingerprinting via specific markers like pyrrole-2,3,5-tricarboxylic acid (PTCA), pyrrole-2,3-dicarboxylic acid (PDCA) and 4-amino-3-hydroxyphenylalanine (AHP). Conversely, biological approaches, primarily utilizing ligninolytic enzymes such as laccases and peroxidases that catalyze the oxidative breakdown of complex melanin structures, offer the most sustainable route for applied degradation. We critically evaluate emerging biotechnological solutions, including immobilized nanobiocatalysts like LiP@MFO-GO (LiP immobilized onto graphene oxide coated magnetic nanoparticles), engineered synergistic laccase-peroxidase complexes for in situ H 2 O 2 recycling, and the use of glutathione peroxidase (GPX) from lysosome-related extracts, highlighting their stability and reusability under industrial conditions. Finally, we outline a strategic framework to overcome mediator toxicity and ensure the generation of biocompatible fragments, providing a roadmap for innovative applications in cosmetics, food preservation, and environmental remediation.

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