Kinetic modeling and stability enhancement of laccase from Trametes sanguinea IIP-32 for sustainable xenobiotic degradation

Abstract

Chlorophenols are recalcitrant xenobiotics classified as priority pollutants due to their high toxicity and environmental persistence. This study evaluates an integrated bioprocess framework for the production, characterization, and application of laccase (TsLac) from Trametes sanguinea IIP-32. Fungal growth, substrate utilization, and TsLac production were mathematically modeled to determine key kinetic parameters. Biomass kinetics followed a logistic growth model (X_max = 6.14 g L⁻¹, μ_max = 1.1 d⁻¹), while the Luedeking-Piret model confirmed that TsLac production is predominantly non-growth-associated. The TsLac demonstrated high thermal stability with a half-life of 32 h at 50 °C, which was extended to 37 h and 46 h using PEG-4000 and glycerol, respectively. The TsLac exhibited substantial biochemical robustness, retaining activity across diverse metal ions, inhibitors, and organic solvents. Sorbitol and sucrose supplementation provided superior lyoprotection during lyophilization. TsLac treatment of 2-chlorophenol (2-CP, 1500 mg L⁻¹) achieved a maximum degradation efficiency of 77%. In untreated (UT) 2-CP, seed germination was completely inhibited; however, treated samples restored seed germination to 100% in Phaseolus mungo, Cyamopsis tetragonoloba, and Sorghum vulgare. Furthermore, TsLac treatment enabled root growth recovery of 17–22% in monocots and 21–62% in dicots relative to water control lengths, indicating recovery from the absolute inhibition of UT samples. These results confirm partial detoxification, as residual metabolites continue to exert physiological stress on seedling development. This study highlights TsLac potential for phenolic effluents treatment while emphasizing the ecological assessments to evaluate the transition from acute toxicity to environmental biocompatibility.