Laccases are extensively used for various purposes due to their broad substrate spectrum. Strategies to improve the production of laccase are not relatively effective relative to the high demand for laccase. Therefore, the development of novel, highly efficient methods for laccase production continues to be a subject of research interest.

Researchers with Institute of Process Engineering (IPE) developed an efficient intermittent ultrasonic treatment strategy to improve laccase production from Trametesversicolor mycelia cultures.

The optimized strategy consisted of exposing 2-day-old mycelia cultures to 5-min ultrasonic treatments for two times with a 12-h interval at the fixed ultrasonic power and frequency (120W, 40 kHz). After 5 days of culture, this strategy produced the highest extracellular laccase activity of 588.9 U/L among all treatments tested which was 1.8-fold greater than the control without ultrasound treatment.

The ultrasonic treatment resulted in a higher pellet porosity that facilitated the mass transfer of nutrients and metabolites from the pellets to the surrounding liquid.

Furthermore, the ultrasonic treatment induced the expression of the laccase gene (lcc), which correlated with a sharp increase in both extracellular and intracellular laccase activity.

This is the first study to find positive effects of ultrasound on gene expression in fungal cells. It brings a new insight to the mechanism for the enhancement of fungal metabolite stimulated by ultrasound. These results present new opportunities and challenges for understanding and improving the culture of filamentous fungi by ultrasonic stimulation.

The paper was published in Ultrasonics Sonochemistry.