High-yield Trichoderma asperellum laccase from microwave-LiCl composite mutagenesis and optimization

The original strain of Trichoderma asperellum was subjected to mutagenesis using microwave irradiation and LiCl, followed by screening for high-yield laccase mutants via the guaiacol method.Optimal fermentation conditions were identified through single-factor and orthogonal experiments.The results indicated that a high-yield mutant strain, MP1-1, was obtained after 15 s of microwave mutagenesis and LiCl treatment at a concentration of 0.9 g/l, achieving a lethality rate of 90%.This mutant exhibited a 70.8% increase in laccase activity compared to the original strain.The optimized fermentation conditions were determined as follows: glucose as the carbon source, yeast extract as the nitrogen source, pH 6.0, Cu 2+ concentration of 0.09 mmol/l, inoculum volume of 1%, and culture temperature of 28 C.Under these conditions, the laccase activity reached 54.51 U/l.After a 14-day treatment, the weight loss rate of polyethylene treated with the mutant strain MP1-1 was 0.80%.Scanning electron microscopy revealed significant surface erosion, characterized by pits and holes on the polyethylene, along with the introduction of active functional groups such as carbonyl and ether bonds.The combination of microwave-LiCl compound mutagenesis and optimized fermentation conditions significantly enhanced the laccase production capacity of T. asperellum, providing a robust foundation for its industrial application.