Harnessing Aureobasidium pullulans for Bioremediation of Lignin Derivatives in Biorefinery Wastewater

Wastewater from biorefineries often contains high concentrations of complex organic pollutants, including lignin derived phenolic compounds, which are toxic and difficult to degrade using conventional wastewater treatment methods1. Efficient treatment of wastewater containing lignin derivatives remains a significant challenge in biorefinery operations, impacting both process economics and environmental sustainability. Fungi offer promising potential in bioremediation due to their ability to produce extracellular enzymes that degrade complex organic molecules, including recalcitrant pollutants such as lignin2. Their adaptability to diverse environmental conditions and ability to form biofilms further enhance their capacity to break down and metabolize these compounds, making them valuable in treating contaminated wastewater. This study aims to investigate the potential of Aureobasidium pullulans, a polymorphic black yeast-like fungus known for its resilience, phenotypic plasticity, and ability to produce various extracellular enzymes, to bioremediate lignin-derived compounds in biorefinery wastewater streams. We observed and quantified the fungal growth patterns and morphological changes of A. pullulans in lignin derivative over time using time-lapse imaging with a transmitted light system (EVOS M7000, ThermoFisher Scientific). The obtained results demonstrate significant variations in colony form, dimension, and cellular morphology across different lignin derivatives, highlighting A. pullulans' remarkable phenotypic plasticity. These findings provide valuable insights into the dynamic interactions between A. pullulans and lignin-derived compounds in wastewater, opening new avenues for the biological treatment of biorefinery effluents. The ability of A. pullulans to adapt to and metabolize these compounds suggests its potential use in biorefinery wastewater treatment processes. This research contributes to the development of more sustainable biorefinery operations by addressing the critical challenge of wastewater treatment. By demonstrating A. pullulans' potential to remediate lignin derivatives while potentially generating valuable byproducts, our study advances both environmental protection and resource recovery in the bioeconomy.