P133: Studies on culture medium optimization and hydrodynamic conditions to achieve high levels of biomass and laccase production by Pleurotus ostreatus

Fungal laccases have potential uses in diverse industries as they catalyze the oxidation of a broad variety of chemical compounds. Production of laccases by basidiomycetes has been extensively studied but little is known on the synergistic effect of complex compounds and copper as inducers of the synthesis of this enzymes. Similarly, literature on the effect of hydrodynamic conditions in bench scale fermenters over laccase production and its relation with the specific growth rate is also scarce.  In this work we report the increase on laccase production by Pleurotus ostreatus CP-50 through the use of a factorial fractional experimental design 2^6-2 for media optimization,as well as the simultaneous use of copper and soluble lignin in Erlenmeyer flasks cultivations. We also analyzed the influence of the energy dissipation/circulation function (EDCF) on biomass and laccase production in a ten liters fermenter.

After media optimization, mycelial growth and laccase volumetric activity increased 4 and 6 fold, respectively, in relation to the (2 %) malt extract basal medium. The use of an optimized medium and the simultaneous addition of both inducers yielded a maximal fungal growth of 10 mg/mL and laccase production of 12 U/mL.

Specific growth rate (m) showed a linear correlation with EDCF in the range studied (0.24-5.9 KW/m^3.s). The highest laccase production (12 U/mL) was obtained at the lower EDCF level. The highest specific laccase productivity (16 U/gbiomass^.h) was obtained when a combination of EDCF conditions was used, 5.9 KW/m^3.s in the beginning, changing to 0.24 KW/m^3.s after 48 h of cultivation.