Cultivation of the fungus Penicillium janthinellum for xylanase production was studied in a poly(ethylene glycol)/cashew-nut tree gum aqueous two-phase system, using a two-level fractional factorial design. The parameters studied were initial pH, cultivation time, type of agro-industrial residue (oat husk or corn cob), agitation, temperature, and phase-forming polymers. The xylanase produced during fermentation partitioned into the top phase. The agitation and temperature (negative), cultivation time and initial pH (positive) effects proved statistically significant for xylanase production. The highest percentage yield of the xylanase in the top and its production in the top phase, about 97% and 160.7 U/mL, were obtained in cultures of 120 h, 40 rpm, 25°C, and pH 5.0.20618801884Albertsson, P.A., (1986) Partition of Cell Particles and Macromolecules, 3rd Ed., , Wiley Interscience: New YorkSinha, J., Dey, P.K., Panda, T., Aqueous two-phase: The system of choice for extractive fermentation (2000) Appl. Microbiol. Biotechnol., 54, pp. 476-486Persson, I., Tjerneld, F., Hahn-Hagerdal, B., Production of β-glucosidase by Aspergillus phoenicis QM329 in aqueous two-phase systems (1989) Biotechnol. Tech., 3, pp. 265-270Hotha, S., Banik, R.M., Production of alkaline protease by Bacillus thurigiensis H14 in aqueous two-phase systems (1997) J. Chem. Technol. Biotechnol., 69, pp. 5-10Kuboi, R., Umakoshi, H., Komasawa, I., Extractive cultivation of Escherichia coli using poly(ethylene glycol)/phosphate aqueous two-phase system to produce intracellular β-galactosidase (1995) Biotechnol. Prog., 11, pp. 202-207Chen, J.P., Lee, M.S., Enhanced production of Serratia marcescens chitinase in PEG/dextran aqueous two-phase systems (1995) Enzyme Microb. Technol., 17, pp. 1021-1027Antov, M.G., Pericin, D.M., Dimic, G.R., Cultivation of Polyporus squamosus for pectinase production in aqueous two-phase system containing sugar beet extraction waste (2001) J. Biotechnol., 91, pp. 83-87Christian, T.J., Manley-Harris, M., Richards, G.N., A preliminary study of the use of larch arabinogalactan in aqueous two-phase systems (1998) Carbohydr. Polym., 35, pp. 7-12Skuse, D.R., Norris-Jones, R., Yalpani, M., Brooks, D.E., Hydroxypropyl cellulose/poly(ethylene glycol)-co-poly(propylene glycol) aqueous two-phase systems: System characterization and partition of cells and proteins (1992) Enzyme Microb. Technol., 14, pp. 785-790Venâncio, A., Teixeira, J.A., Mota, M., Evaluation of crude hydroxypropyl starch as a bioseparation aqueous two-phase-forming polymer (1993) Biotechnol. Prog., 9, pp. 635-638Oliveira, L.A., Sarubbo, L.A., Porto, A.L.F., Campos-Takaki, G.M., Tambourgi, E.B., Partition of trypsin in aqueous two-phase systems of poly(ethylene glycol) and cashew-nut tree gum (2002) Process Biochem., 38, pp. 693-699Sarubbo, L.A., Oliveira, L.A., Porto, A.L.F., Duarte, H.S., Carneiro-Leão, A.M.A., Lima-Filho, J.L., Campos-Takaki, G.M., Tambourgi, E.B., New aqueous two-phase system based on cashew-nut tree gum and poly(ethylene glycol) (2000) J. Chromatogr. B, 743, pp. 79-84Paula, R.C.M., Rodrigues, J.F., Composition and rheological properties of cashew tree gum, the exudate polysaccharide from Anacardium occidentale L. (1995) Carbohydr. Polym., 26, pp. 177-181Rodrigues, J.F., Paula, R.C.M., Costa, S.M., (1993) Polim. Cienc. Tecnol., 3, pp. 31-36Milagres, A.M.F., (1988) Alguns Aspectos Da Regulação de β-Xilanases Extracelulares de Penicillium Janthinellum, , Viçosa: Tese de Mestrado, UFVVogel, H.J., A convenient growth medium for Neurospora crassa (Medium N) (1956) Microb. Gen. Bull., 13, pp. 42-43Bailey, M.J., Biely, P., Poutanen, K., Inter-laboratory testing of methods for assay of xylanase activity (1992) J. Biotechnol., 23, pp. 257-270Miller, G.L., Use of dinitrosalicylic acid reagent for determination of reducing sugar (1959) Anal. Chem., 31, pp. 426-428Sedmak, J.J., Grossberg, S.E., A rapid, sensitive, and versatile assay for protein using Coomassie brilliant blue G250 (1977) Anal. Biochem., 79, pp. 544-1522Oliveira, L.A., Sarubbo, L.A., Porto, A.L.F., Lima-Filho, J.L., Campos-Takaki, G.M., Tambourgi, E.B., Physical and rheological characterisation of poly(ethylene glycol)-cashew-nut tree gum aqueous two-phase systems (2002) J. Chromatogr. B, 766, pp. 27-36Barros Neto, B., Scarminio, I.S., Bruns, R.E., (2001) Como Fazer Experimentos: Pesquisa e Desenvolvimento Na Ciência e Na Indústria, 1st Ed., , UNICAMP: BrazilHaltrich, D., Nidetzky, B., Kulbe, K.D., Steiner, W., Zupancic, S., Production of fungal xylanases (1996) Bioresour. Technol., 58, pp. 137-161Parajó, J.C., Domínguez, H., Dominguez, J.M., Biotechnological production of xylitol. Part 3: Operation in culture media made from lignocellulose hydrolysates (1998) Bioresour. Technol., 66, pp. 25-40Costa, S.A., Pessoa Jr., A., Roberto, I.C., Partitioning of xylanolytic complex from Penicillium janthinellum by an aqueous two-phase system (2000) J. Chromatogr. B, 743, pp. 339-348Bim, M.A., Franco, T.T., Extraction in aqueous two-phase systems of alkaline xylanase produced by Bacillus pumilus and its application in kraft pulp bleaching (2000) J. Chromatogr. B, 743, pp. 349-356Kulkarni, N., Vaidya, A., Rao, M., Extractive cultivation of recombinant Escherichia coli using aqueous two phase systems for production and separation of extracellular xylanase (1999) Biochem. Biophys. Res. Commun., 255, pp. 274-278