No abstract

Six Penicillium strains were isolated from soil at a depth of 0 15 cm in the Juréia-Itatins Ecology Station (JIES), in the São Paulo State, Brazil. They were evaluated for xylanase production under different temperatures and carbon sources. The best carbon source and temperature were first determined in an automated Bioscreen C system, verifying the growth of microorganisms. Liquid media containing tap water with 2% carbohydrate and/or 1% nitrogen sources were used. Afterwards, Penicillium citrinum, P. fellutanum, P. rugulosum and P. decumbens were cultivated in 250 mL Erlenmeyer flasks with 50 mL of culture medium containing tap water sole 2% carbon source (fructose, glucose, mannitol, sucrose or xylose) and 1% yeast extract as a nitrogen source at pH 5.0 and 28o C, with agitation of 150 rpm for 72 hours. These same strains, except P. decumbens, and P. purpurogenum were cultivated in solid substrate with wheat bran under the same environmental conditions to study the potential of xylanase activity. Maximum xylanase activity was observed in cultures with wheat bran, without the addition of any other carbon source, using inocula containing 1 x 107 spores.mL-1 (28o C, pH 5.0, 72 h). It can be concluded that P. fellutanum and P. citrinumare a good xylanase producers under the conditions of 28º C. The results of xylanase activity were 54% less at 28º C in liquid cultures media cultures than in solid substrate.