Abstract

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 Mn 2+ 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 Mn 2+, 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, Cu 2+ or Ag +, but not Zn 2+ or Cd 2+, led to an accumulation of lcs transcripts only in cultures grown in the absence of Mn 2+. 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 Mn 2+. In the course of these studies it was observed that Mn 2+ 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. © 2007 Federation of European Microbiological Societies.