Manganese affects the production of laccase in the basidiomycete Ceriporiopsis subvermispora

The authors have previously identified and characterized lcs, a gene encoding laccase in the white-rot basidiomycete Ceriporiopsis subvermispora. In this work, the effect of Mn²⁺ in the production of extracellular laccase in liquid cultures of this fungus has been assessed. It was observed that at low (0-10 μM) concentrations of Mn²⁺, high titers of lcs-mRNA were obtained, whereas at high (160-194 μM) concentrations of this metal ion, transcripts levels decreased markedly. This phenomenon was observed at different days of growth. On the other hand, Cu²⁺ or Ag ⁺, but not Zn²⁺ or Cd²⁺, led to an accumulation of lcs transcripts only in cultures grown in the absence of Mn²⁺. A dramatic increase in lcs transcript levels was also obtained with syringic acid, a lignin-related aromatic compound. This effect was more pronounced in cultures lacking Mn²⁺. In the course of these studies it was observed that Mn²⁺ stimulates mycelium growth. Thus, although extracellular laccase activity appeared higher in cultures containing 160 or 194 μM Mn ²⁺, i.e. when lcs transcripts were lower, a correlation between lcs-mRNA levels and enzymatic activity was observed when values of the latter were corrected by the amount of mycelium present in the cultures.