Laccase production by some Phlebia species

The present study was carried out to examine the ability of four species of the genus Phlebia, viz. P. floridensis, P. brevispora, P. radiata and P. fascicularia, to produce the ligninolytic enzyme laccase in liquid culture. P. floridensis was the most active species that even surpassed laccase production by Trametes versicolor, and was chosen for further study. Among several carbon sources tested, malt extract turned out to be the best medium for subsequent laccase concentration by ammonium sulfate precipitation. Specific enzyme activity increased 12-fold during this procedure and a K(m) value of 0.33 mM was calculated for the resulting laccase preparation using guaiacol as the substrate. Concentrated laccase from P. floridensis was relatively thermostable and retained 70% and 15% of its activity after 1 h preincubation at 50 degrees C and 60 degrees C, respectively.