Laccases are enzymes involved in lignin degradation and are produced by various organisms. Due to their low substrate specificity their potential to be used in biotechnological applications has received attention. The addition of laccase inducers to the culture medium of microorganisms can enhance laccase production and facilitate its purification and utilization. The aim of this study was to investigate the effect of some compounds as laccase inducers in cultures of Lentinula edodes (shiitake). First, it was selected a culture medium suitable for laccase production by shiitake using two levels of N (2.6 and 26 mM) and seven levels of Cu (0, 50, 100, 150, 200, 250 and 300 µM). The medium with 2.6 mM N and 250 µM Cu was found to provide the highest laccase activity. To the selected medium it were added gallic acid (1 mM), catechol (1 mM), ammonium tartrate (55 µM), hydroxybenzoic acid (1 mM) and vanillin (1 mM). The two first compounds completely inhibited laccase activity and a 30 day time course experiment was carried out with the remaining compounds. Only cultures with ammonium tartrate exhibited laccase activity higher than control cultures, reaching 251 U/ mL of extract after 30 days. A native-PAGE was performed and showed only one band, suggesting that no isozyme was produced.

RESUMOO objetivo deste trabalho foi acompanhar possíveis mudanças nos atributos indicadores da qualidade do solo em povoamentos de eucalipto, mediante utilização de irrigação e fertirrigação de efluente de uma fábrica de celulose, por meio de um modelo matemático que expressa o Índice de Qualidade do Solo (IQS), utilizando-se atributos microbiológicos e químicos. Foram instalados dois experimentos distintos, ambos dispostos em parcelas subdivididas, sendo um na posição de baixada e o outro na posição de encosta, no município de Belo Oriente -MG, com solos classificados como Neossolo Flúvico e Latossolo Amarelo, respectivamente. Foram considerados os seguintes tratamentos: irrigação até a máxima evapotranspiração (Irrigação), fertirrigação até a máxima evapotranspiração com 100% da adubação recomendada pela demanda nutricional da planta (Irrigação -Adubação) e fertirrigação com efluente de celulose (Irrigação -Efluente). Amostras de solos de áreas de eucalipto e de duas outras consideradas como referência (mata secundária e pastagem) foram coletadas em 2003, durante duas épocas do ano (períodos chuvoso e seco), sob posição de baixada e de encosta, e analisadas quanto aos atributos microbiológicos e químicos para determinação dos IQS. Os atributos químicos mostraram-se mais sensíveis ao efeito do uso e manejo do solo que ao efeito de época. Os IQS apresentaram comportamento similar entre os tratamentos apenas para a posição de encosta (Latossolo Amarelo), mas não para a de baixada (Neossolo Flúvico).Palavras-chave: Efeito sazonal; posição topográfica; efluente de celulose; atividade microbiana. ABSTRACTThe objective of this work was to follow possible changes in the indicators attributes of the quality of soils in settlemens of eucalypt by means of use of irrigation and fertirrigation of effluent of a cellulose plant, by means of a mathematical model that express the Index of Quality of Sol (IQS), using microbiological and chemical attributes. Two experiment distinct were installed, both made use in subdivided parcels, being one in the valley position and the other in the slope position, in the city of Belo Oriente -MG, with classified soils as Fluvic Neosol and Yellow Latosol, respectively. The following treatments were considered: irrigation until the maximum evapotranspiration (Irrigation), fertirrigation until the maximum evapotranspiration with 100% of the fertilization recommended for the demand nutritional of the plant (Irrigation -Fertilization) and fertirrigation with effluent of cellulose (Irrigation -Effluent). Samples of soils of areas of eucalypt and two others considered as reference (secondary forest and pasture) had been collected in 2003, during two periods of the year (rainy and dry), under valley position and slope, and analyzed how much to the microbiological and chemical attributes for determination of the IQS. The chemical attributes showed more sensible to the effect of the use and management of the soil that time effect. The IQS presented similar behavior between the treatments only for the...