Background: Laccases are multi-copper enzymes that oxidize phenolic/aromatic compounds
and represent a promising alternative to environmental decontamination processes and
Objective: The effects of pH and temperature on the growth and the production of laccases during
the cultivation of Pleurotus sajor-caju PS-2001 in stirred-tank bioreactor were assessed.
Methods: Assays were performed at fixed pH values from 4.5 to 7.5 (28°C) and at temperatures
from 24 to 36°C (pH 6.5).
Results: In pH testing, larger biomass concentration (4.5 g L-1) was reached at pH 5.5, whereas concentrations
of 3.7, 3.1 and 1.7 g L-1 were measured at pH 4.5, 6.5 and 7.5, respectively. With ABTS
as substrate, peaks of laccases activity of 50, 30 and 24 U mL-1, at pH 6.5, 5.5 and 7.5, respectively,
were detected. Under different temperatures, higher mycelial concentrations (3.0 g L-1) were
quantified at 66 hours at 28°C, while concentrations below 2.0 g L-1 were observed at 24, 32, and
36°C. Maximum laccases activities of 50, 42, 6 and 5 U mL-1 were obtained at 28, 32, 24, and
36°C, respectively. In all tests, the presence of other phenol oxidases – total peroxidase, manganese
peroxidase, lignin peroxidase and veratryl alcohol oxidase – was observed.
Conclusion: The results indicate that variations in pH and temperature during fungal cultivation
strongly affect the enzymatic activity and growth kinetics of P. sajor-caju PS-2001 in a stirredtank