5-23: Production of laccase by fungi isolated from soil of differents times of sugarcane crop

Isolation and identification of microorganisms with ability to produce biocatalysts have a great importance for presentation of "new" enzymes to the biotechnological business. Laccase is an oxidoreductase able to catalyze the oxidation of many aromatic compounds (particularly phenols) and have many environmental and biotechnological applications, including bioconversion of lignocellulosics compounds, wastewater treatment, as well as soil bioremediation. In this study, were isolated 75 fungi strains from sugarcane soil, with different carbon sources (glucose, sugar-cane bagasse, wheat bran and filter paper) and at different times of the crop season. Among the isolates, were found 10 different genus, such as Trichoderma (40%), Fusarium (15%) and Cunninghamella (13%), Aspergillus (12%), Mucor (8%). The genera Aspergillus, Cunninghamella, Fusarium and Trichoderma were isolated in all carbon sources media and only Trichoderma, Fusarium, Mucor were found in all different times of the crop. The isolates were used for a solid-state fermentation, with sugarcane bagasse and wheat bran as substrates, to evaluate their potential to produce laccase. The enzyme activity was quite varied, and the genera Verticillium (500 U/L), Fusarium (273 U/L) and Mucor (240 U/L) were the ones that showed the highest lacase activities. Was observed that the highest laccase productions by isolates happened after application of herbicides in the soil showing that the presence of xenobiotics may induce the production of this enzyme by fungi.