An Updated Perspective on the Aromatic Metabolic Pathways of Plant-Derived Heterocyclic Aromatic Compounds in Aspergillus niger

Aromatic compounds are vital in both natural and synthetic chemistry, traditionally sourced from non-renewable petrochemicals. However, plant biomass, particularly lignin, offers a renewable alternative source for aromatic compounds. Lignin, a complex polymer in plant cell walls, is the largest renewable source of aromatic compounds, though its degradation remains challenging. Lignin can be chemically degraded through oxidation, acid hydrolysis or solvolysis. Microorganisms, including fungi, offer a sustainable alternative in breaking down lignin into valuable compounds. Fungi possess unique enzymes capable of converting aromatic compounds derived from lignin into biofuels, bioplastics, and chemical building blocks. However, their aromatic metabolic pathways are less studied compared to bacterial systems. Recent advances in genomics, proteomics, and metabolic engineering are helping to reveal these pathways, offering new opportunities to optimize fungi for lignin bioconversion. By manipulating these pathways, researchers aim to enhance lignin valorization, contributing to sustainable biobased industries. This review highlights recent progress in understanding fungal aromatic metabolism, focusing on how Aspergillus niger converts plantderived aromatic compounds into useful products and the versatility of aromatic metabolism within the Aspergillus genus. Addressing the current knowledge gaps in fungal pathways could unlock their potential in sustainable technologies, promoting eco-friendly production of biofuels and chemicals from renewable resources.