Aureobasidium is a genus of highly adaptable, yeast-like fungi that are widely distributed as saprophytes across various ecosystems. Demonstrating remarkable resilience, Aureobasidium can survive in environments characterized by extreme pH levels and high salinity. Furthermore, this fungus is notable for its production of various secondary metabolites with considerable biotechnological potential, such as polyol lipids, pullulan, and polymalate. Additionally, Aureobasidium can grow on a wide range of carbon sources, including renewable raw materials and waste products, positioning it as a candidate for a novel, robust platform organism.

Lignin, one of the most abundant renewable resources on earth, is highly underutilized and largely wasted. The aromatic compounds of this polymer can be a promising feedstock for a wide range of value-added chemicals. Here, we demonstrate that Aureobasidium pullulans can grow on a multitude of lignin-derived aromatic monomers like catechol or coumarate, even at extreme pH values. Toxicity tests revealed that the fungus can withstand high concentrations of these aromatics. Moreover, the ability to grow on mixtures of aromatic compounds found in lignin hydrolysates was also proven, while the production of the bioprivileged molecule muconic acid from the aromatics could be observed.

However, metabolic engineering tools are still rare and thus hinder the advancement of Aureobasidium towards a novel platform organism. To address this challenge, a genetic toolbox based on the CRISPR-Cas9 method was developed in A. pullulans, enabling scarless genomic modifications, integration of multiple genes, and a tuneable gene expression.

Expanding the substrate spectrum towards sustainable renewable substrates and the development of genetic tools are the first steps in establishing A. pullulans as a new versatile platform organism contributing to a sustainable bio-economy.