Enhancing Laccase and Manganese Peroxidase Activity in White-Rot Fungi: The Role of Copper, Manganese, and Lignocellulosic Substrates

White-rot fungi (WRF) are increasingly recognized for their biotechnological potential due to the wide range of applications of ligninolytic enzymes. The addition of different metals involved in the functioning of ligninolytic enzymes, mainly copper and manganese, has been widely studied to maximize the enzymatic activities of the WRF. This review aims to provide information on the effect of metal-fungi interaction mechanisms that justify the effects of enzymatic activity. The addition of copper is associated with increased laccase activity, with reported improvements in the laccase activity compared to controls without metal addition of up to 100% at doses between 0.5–1 mM. The addition of manganese resulted in an improvement in manganese peroxidase activity with respect to the control at the wide range of 1–18.2 mM. Furthermore, enzymatic activity was generally favored by using substrates with lignocellulosic fibers with respect to synthetic culture medium. Quantifying the concentration of metals in the substrate is required to monitor bioavailable metals for fungi in these assays accurately, making an external contribution less necessary.