Background: Ethanol has been pointed out as a laccase inducer. However,
there are controversial reports about its efficiencywith some fungi. In
this study,we hypothesized that ethanol laccase induced in Pycnoporus
sanguineus depends on nitrogen nutriment conditions. To prove this,we
assessed laccase production in submerged cultures of P. sanguineus,with
different nitrogen concentrations andwith, orwithout ethanol added in a
factorial designed experiment. Results: In order to analyze the effects
of factors on the response variables, a factorial ANOVA, and
response-surface models were performed. It was found that the nitrogen
source was the main factor that affected laccase production in P.
sanguineus. The treatments with yeast extract (2 g/L) and ethanol (3
g/L) induced the highest laccase activity (31.01 \ub1 4.9 U/L), while
the treatments with urea reached the lowest activity (less than 1.6
U/L). Ethanol had positive and synergic effects on laccase production,
in accordance with the surface response model, as long as simple
nitrogen sources (urea) were not available. Conclusions: We suggest
that laccase in P. sanguineus is regulated by a catabolic nitrogen
repressionmechanism; laccase activity is strongly inhibited by urea
used as nitrogen source and it decreases when the amount of urea
increases; contrarily, a synergic positive effect was observed between
yeast extract and ethanol on laccase production