Unlocking the potential of microalgae for bioleaching: a review of mechanisms, challenges, and future prospects

Bioleaching has become an eco-friendly alternative to traditional mining methods for recovering metals. While bacteria and fungi have long been used in bioleaching because of their ability to dissolve metals through metabolic activities, recent studies have shown that microalgae also hold significant promise in this field. Microalgae offer unique benefits, such as the ability to regenerate biomass, capture CO2, and produce bioactive compounds that aid in metal extraction. This review examines how microalgae contribute to bioleaching, particularly through processes like biosorption, bioaccumulation, and bioprecipitation. Microalgae can generate organic acids and chelating agents that improve the solubility of metals, making them a promising option for extracting valuable metals from ores, electronic waste, and industrial byproducts. However, microalgae-based bioleaching still faces challenges, such as lower efficiency compared to bacterial systems, the need for strain improvement, and issues related to scaling up. To enhance bioleaching performance, it is essential to understand how culture conditions, metabolic pathways, and potential genetic modifications influence the process. This review provides a detailed analysis of current research, identifying key microalgal species used in bioleaching and comparing their effectiveness to bacteria and fungi. It also explores strategies to improve metal recovery, such as co-cultivation methods, advancements in bioreactor design, and metabolic engineering. Integrating microalgal bioleaching into circular economy models and sustainable metal recovery processes offers exciting opportunities for future research and industrial applications.