Effects of Physical Plasma on Biotechnological Processes in Mycelia of the Cultivated Lingzhi or Reishi Medicinal Mushroom Ganoderma lucidum (Agaricomycetes)

Physical plasma as the fourth state of matter comprises highly reactive particles (e.g., reactive species) and different types of radiation. It can be generated under standardized conditions at atmospheric pressure and low temperatures. Plasma is able to generate high-yielding bacterial strains, but this technique has not previously been applied to improve biotechnological processes in medicinal mushrooms. Our study investigated the influences of plasma on the growth and productivity of mycelial cultures of Ganoderma lucidum. Mycelia of G. lucidum were treated as solid pieces or suspended in Hagem medium using 3 different plasma sources: surface dielectric barrier discharge (DBD) plasma source, volume DBD plasma source, and the kINPen09 plasma jet. Treated mycelia were analyzed for biomass production, extract yield, and secondary metabolites. The plasma jet increased total triterpene content. Both DBD plasma sources led to elevated ergosterol content. Increased Β-l-3-D-glucan content was found after exposure to the volume DBD- or kINPen09-treated medium. The changes observed seemed to be dependent on total energy input by the plasma sources and the kind of mycelial treatment (solid piece or suspension; direct treatment or application of plasma-treated medium). In conclusion, physical plasma might be a useful tool for optimizing biotechnological processes in medicinal mushrooms. Further investigations are necessary to clarify whether these changes are stable and heritable, and whether effects can be achieved with other fungal species.