Produção e caracterização do complexo xilanolítico de Penicillium janczewskii

Abstract

Especies de Penicillium estao entre os fungos mais comumente encontrados na natureza. Sao eximios degradadores de materia organica apresentando, assim, papel fundamental nos habitat que ocupam. Neste trabalho, uma linhagem de Penicillium janczewskii, isolada do solo da Mata Atlantica, foi avaliada quanto a producao de xilanases e ß-xilosidases, enzimas responsaveis pela degradacao da xilana presente na materia vegetal. Alem disso, o outro objetivo desse trabalho foi caracterizar ambas as atividades no filtrado de cultura. A xilana de aveia mostrou-se a melhor fonte de carbono para inducao dessas enzimas seguida do farelo de trigo. A producao enzimatica tambem foi induzida, em niveis inferiores, por outros substratos lignocelulosicos. Ressalta-se ainda que nao houve producao de celulases, exceto em meios com farelo de trigo, farelo de aveia e lactose, nos quais baixos niveis foram produzidos. O estudo cinetico das atividades enzimaticas indicou niveis mais elevados de xilanase em culturas de 7 dias de idade, e de ß-xilosidases em culturas de 8 dias. A linhagem se desenvolveu bem na faixa de pH entre 3,0 e 9,0 em temperaturas entre 20 e 35 °C, sendo selecionados o pH 6,5 e 30 °C e o pH 5,0 e 25 °C como condicoes para producao das maiores atividades xilanasica e ß-xilosidasica, respectivamente. As condicoes otimas de atividade xilanasica foram pH 5,0 e 50 °C, e para a ß-xilosidase foram pH 4,0 e 75 °C, temperatura bastante elevada considerando o carater mesofilico desse microrganismo. A atividade xilanasica apresentou-se mais estavel em pHs de 6,0 a 9,5, enquanto a atividade ß-xilosidasica apresentou-se mais estavel em pHs acidos, de 1,6 a 5,5, faixa na qual manteve praticamente 100 % da atividade. As meias-vidas da atividade xilanase a 40, 50 e 60 °C foram de 183, 15 e 2,8 min, respectivamente. A atividade ß-xilosidasica apresentou...

Species of Penicillium are among the most common fungi found in the nature. They are excellent organic matter degraders, playing an important role in the habitat they live. In this work, a Penicillium janczewskii strain, isolated from soil of Atlantic Forest, was valuated for the production of xylanase and ß-xylosidase, enzymes responsible for degradation of xylan present in the vegetal material. Moreover, another aim of this work was to characterize both activities in the culture filtrate. Oat spelts xylan was the best inducer carbon source to these enzymes, followed by wheat bran. The enzymatic production was also induced, in inferior levels, for others lignocellulosic substrates. It was observed that the strain did not produce celulases, except when cultivated in medium with wheat bran, oat bran and lactose, in which low levels were produced. The kinetic study of the enzymatic activities indicated higher levels of xylanase in 7 days-old cultures and higher levels of ß-xylosidase in 8 daysold cultures. The strain developed well in pH between 3.0 and 9.0 and in temperature between 20 and 35 °C. It was selected pH 6.5 and 30 °C, and pH 5.0 and 25 °C as the conditions for highest production of xylanase and ß-xylosidase activities, respectively. The optima conditions for xylanase activity were pH 5.0 and 50 °C, and for ß-xylosidase activity were the pH 4.0 and 75 °C, an elevated temperature considering the mesophilic character of this microorganism. The xylanase activity was more stable in pH from 6.0 to 9.5, while the ß-xylosidase activity was more stable in acid pH, between 1.6 and 5.5, maintaining practically 100 % of the activity in this range. The half-lives of the xylanase activity at 40, 50 and 60 °C was 183, 15 and 2.8 min, respectively. The ß-xylosidase activity presented T50 of 144, 7.6 and 4.2 min at 50, 65 and 75 °C, respectively... (Complete abstract click electronic access below)