Monday, May 4, 2009
5-69
Changes in Pleurotus ostreatus laccase isoenzyme pattern in cocultivation with Trichoderma viride
Martha Alicia Contreras-Ordónez, Leobardo Serrano, and Enrique Galindo. Cellular Engineering and Biocatalysis, Instituto Biotecnologia UNAM, Edo Guanajuato 81 Providencia, Mexico City, Mexico
Laccases are phenoloxidases involved in aromatic compound transformation but also in stress response towards antagonist species such as Trichoderma sp. Increase laccase production during interespecific Trichoderma-basidiomycetes interactions is an environmentally safe biological alternative to chemical induction, which has received considerable research efforts in the last years. Pleurotus ostreatus was cultivated in liquid media containing malt extract. In the control cultures a sharp decreased on the laccase volumetric activity was observed, however the cocultures maintained 57 % of their highest laccase activity obtained at 72 hours after inoculation of T viride. During the cocultures T viride induced changes in the laccase isoenzyme pattern as a result of the alteration of laccases secreted by P ostreatus, modifying lcs1 to lcs3. The Km values of lcs3 for two phenolic substrates were lower than those of lcs1 indicating that with the processing to which the isoenzyme was subjected increased the affinity to certain substrates.