White-rot fungi play important roles in the global carbon cycle by efficiently degrading lignin and polysaccharides from lignocellulose. Over the years, extensive efforts have been made to elucidate the mechanisms underlying lignin degradation by white-rot fungi. One of them is a molecular genetics approach, which includes genetic modification to alter wood-degrading abilities or metabolism, with the aim of producing commercially valuable chemicals from unutilized lignocellulosic resources. Molecular genetic studies have been conducted on several species, including Pleurotus ostreatus, Phanerochaete sordida, and Phlebia sp., for which a genetic transformation system has been developed. However, the techniques and methodologies available for these fungi are limited, posing a serious bottleneck. Here, we describe recent studies that have developed powerful and effective techniques and methodologies, removing the restrictions of molecular genetics studies on lignin degradation by white-rot fungi.

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Hydroxybenzaldehydes (HBAs) are ubiquitous in reaction mixtures obtained from various types of lignin degradation, particularly oxidative degradation. This article reviews the formation behaviors, pathways, and mechanisms of HBAs during alkaline nitrobenzene and alkaline aerobic oxidations of lignin. The former is a well-known analytical method for lignin, while the latter is of industrial importance from the viewpoint of the production of bio-based aromatics.

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