Influence of Trace Elements on Ligninolytic Enzyme Activity of Pleurotus ostreatus and P. pulmonarius

Trace elements, at tolerable concentrations, are either part of the active site or act as an activity modulator of ligninolytic enzymes of white-rot mushrooms. They are usually in plant raw materials in a non-toxic amount or non-available and extractable forms. This study evaluated the effects of Fe, Zn, and Se on the activity of laccase and Mn-oxidizing peroxidases of P. ostreatus and P. pulmonarius during solid-state fermentation of grapevine sawdust. The studied species showed different levels of tolerance to the trace elements. A stimulatory effect of the microelements on laccase activity was demonstrated in P. ostreatus, while Fe and Zn were strong inhibitors of the activity of P. pulmonarius, which was contrary to Se, independent of the cultivation period. With the exception of SeO2, activity of Mn-oxidizing peroxidases in P. ostreatus was suppressed in various levels by the elements. However, in P. pulmonarius, activity against phenol red oxidation in the presence of external Mn 2+ was stimulated by the elements on day 7, while on day 10, activity inhibition by Fe and Zn and stimulation by Se was noted. The effect on activity against phenol red oxidation in the absence of external Mn 2+ was the opposite.