Comparative Transcriptomic and Physiological Analysis of Extremophilic and Non-Extremophilic Fungi in Bioremediation of Cadmium (Cd) and Strontium (Sr)

Heavy metal and nuclide contamination pose increasing threats to the environment and public health. In this study, a comparative analysis was conducted on the bioremediation capabilities of the halophilic fungus Engyodontium album (E. album) and the non-halophilic fungus Trichoderma reesei (T. reesei) under cadmium (Cd) and strontium (Sr) stress. Biosorption tests, scanning electron microscopy (SEM), and transcriptomic analyses were performed to assess the fungi's physiological and molecular responses to 100 ppm of Cd and Sr. The results revealed that E. album exhibited superior biosorption capacity for both Cd and Sr, significantly outperforming T. reesei. Transcriptomic analysis identified the upregulation of metal-degrading enzymes and enhanced antioxidant defences in E. album, with increased activity in the MAPK signalling pathway. In contrast, T. reesei demonstrated lower tolerance and remediation efficiency, with significant gene expression changes under stress conditions, particularly in reactive oxygen species detoxification mechanisms. These findings suggest that extremophilic fungi like E. album hold significant promise for eco-friendly bioremediation applications due to their robust metabolic adaptations to heavy metal stress. This study is the first to compare extremophilic and non-extremophilic fungi in response to heavy metal contamination, providing valuable insights for future environmental remediation strategies.