Role of proteins in phytoremediation and mycoremediation for heavy metal removal: a focus on protein-based remediation.

Heavy metal contamination is a global issue caused by persistent, toxic, and bioaccumulative elements such as cadmium, lead, arsenic, chromium, and mercury. Unlike organic pollutants, these metals resist biodegradation and accumulate in soils, water, and living organisms, creating severe ecological and health risks. Conventional remediation techniques are expensive, energy-intensive, and produce secondary waste, driving the need for sustainable alternatives. Bioremediation, particularly phytoremediation and mycoremediation, has emerged as an eco-friendly and cost-effective strategy. Recent studies highlight the central role of proteins and peptides in these processes. In plants, metal transporters, metallothioneins, phytochelatins, and redox enzymes regulate the uptake, detoxification, and sequestration of metals, while fungi rely on extracellular enzymes, redox-active metabolites, and cell wall proteins for biosorption and transformation. Advances in protein engineering and synthetic biology now enhance the ability of plants and fungi to target and detoxify metals with greater efficiency. The novelty of this review emphasizes the mechanistic contributions of proteins and peptides to bioadsorption, bioaccumulation, and biotransformation, while addressing current challenges related to scalability, environmental variability, and regulatory acceptance. By integrating synthetic biology, nanobiotechnology, and omics-driven protein discovery, we propose design-based frameworks for next-generation remediation that could transform heavy metal cleanup into predictable, programmable, and field-ready technologies.