Strategies for recombinant laccase expression and their roles in environmental remediation.

Laccases are multicopper enzymes capable of oxidizing a wide variety of compounds, standing out as green tools for industrial and environmental applications. However, production from native sources faces limitations that have driven advances in recombinant expression. This scoping review includes studies published between 2019 and 2025, selected from major online databases, describing recombinant fungal and bacterial laccases for environmental applications. Strategies to optimize expression are discussed, including the use of efficient vectors, codon optimization, His-tag addition, mutagenesis, and computational approaches, with an emphasis on their advantages, trade-offs, and limitations. Pichia pastoris is widely used for the expression of fungal laccases, while Escherichia coli is preferred for the expression of bacterial laccases. However, significant variability in expression efficiency and enzyme performance is observed across hosts and constructs. The use of alternative culture media, such as agro-industrial residues, is also explored as a sustainability-driven strategy; however, its applicability remains limited for certain heterologous expression systems. In the environmental field, recombinant laccases demonstrate high efficiency in the degradation of textile dyes, the treatment of lignocellulosic waste, the biodegradation of pharmaceuticals, and the degradation of various toxic compounds, often requiring redox mediators to achieve high conversion rates. Despite significant advances, challenges remain, such as inconsistent catalytic performance among studies and limited stability under extreme temperature and pH conditions. Overall, this review highlights the key challenges in developing recombinant laccase and demonstrates that advances in protein engineering, expression systems, and process optimization are crucial for environmental applications.