Modification of Yarrowia lipolytica via metabolic engineering for effective remediation of heavy metals from wastewater

With the increasing demand for heavy metals due to the advancement of industrial activities, large proportions of heavy metals have been discharged into aquatic ecosystems, causing serious harm to human health and the environment. Existing physical and chemical methods for recovering heavy metals from wastewater encounter challenges, such as low efficiency, high processing costs, and potential secondary pollution. In this study, we developed a novel approach by engineering the endogenous sulphur metabolic pathway of Yarrowia lipolytica, providing it with the ability to produce approximately 550 ppm of sulphide. Subsequently, sulphide-producing Y. lipolytica was used for the first time in heavy metal remediation. The engineered strain exhibited a high capacity to remove various heavy metals, especially achieving over 90 % for cadmium (Cd), copper (Cu) and lead (Pb). This capacity was consistent when applied to both synthetic and actual wastewater samples. Microscopic analyses revealed that sulphide-mediated biological precipitation of metal sulphides on the cell surface is responsible for their removal. Our findings demonstrate that sulphide-producing yeasts are a robust and effective bioremediation strategy for heavy metals, showing great potential for future heavy metal pollution remediation practices.