Optimization of the submerged fermentation process for laccase production by Pleurotus sp. XH005

Objective Industrial production of laccase primarily relies on microbial fermentation; however, microbial fermentation processes for laccase production suffer from low enzyme yields. In this study, a laboratory-preserved fungal strain, Pleurotus sp. XH005, was used to optimize its fermentation process for laccase production.

Methods Through single-factor and response surface optimization experiments, laccase activity of Pleurotus sp. XH005 under various fermentation conditions was measured, and the enzyme production process was optimized. The effects of carbon and nitrogen source concentrations, inoculum size, pH, and metal ion addition on submerged fermentation were investigated.

Results Single-factor experiments identified carbon source concentration, nitrogen source concentration, inoculum size, and metal ion concentration as the four significant factors affecting laccase activity. Response surface analysis determined the optimal fermentation conditions for laccase production to be: glucose 39.45 g/L, yeast extract 5.97 g/L, inoculum size 3.23%, and Cu²⁺ concentration 0.85 mmol/L. Under these conditions, after 8 days of fermentation, the laccase activity reached 480.22 ± 7.53 U/mL, which was 2.81 times that before optimization.

Conclusion The response surface optimization experiment reduced the number of experimental trials and enhanced laccase production, providing an excellent strain for industrial laccase production and an experimental foundation for research on microbial laccase fermentation.