____________________________________________________________________________________________ *Corresponding author: Email: polizeli@ffclrp.usp.br; British Biotechnology Journal 4(1): 30-39, 2014 SCIENCEDOMAIN international www.sciencedomain.org Screening of Filamentous Fungi for Xylanases and Cellulases Not Inhibited by Xylose and Glucose L. F. C. Ribeiro 1 , L. F. Ribeiro 1 , J. A. Jorge 2 and M. L. T. M. Polizeli 2* 1 Immunology and Biochemistry Department of Faculdade de Medicina de Ribeirão Preto – USP, Ribeirão Preto, SP, Brazil. 2 Biology Department of Faculdade de Filosofia Ciências e Letras de Ribeirão Preto – USP, Ribeirão Preto, SP, Brazil. Authors’ contributions This work was carried out in collaboration between all authors. Author LFCR participated in all operations of this manuscript. This work is part of her Doctor thesis. Author LFR carried out the Lichenase and laccase assays. He performed the analysis of data concerning these enzymes. Authors JAJ and MLTMP designed the study and wrote the protocol performed. Author MLTMP revised the manuscript and she is final responsible for all information presented. All authors read and approved the final manuscript. Received 21 st July 2013 Accepted 5 th October 2013 Published 26 th October 2013 ABSTRACT Aims: Screening different filamentous fungi for thermostable xylanases and cellulases that would not be inhibited by xylose and glucose, respectively. Methodology: Samples of fungi collected in the Atlantic forest region, Minas Gerais, Brazil, and some fungi from our Culture Collection were used in this screening. All fungi were grown in liquid media containing 1% sugar cane bagasse (SCB). After that, an aliquot of the crude broth was incubated at different temperatures (from 4 to 60 °C) in carboxymethyl cellulose (CMC) or xylan-media plates, for 12 hours. After this period, the plates were stained with Congo Red. Fungi that presented the best results (larger halos) were tested for the effect of adding xylose and glucose in the xylanase and cellulases activities, respectively. Crude extracts obtained from fungi grown in SCB were used for laccase and lichenase assay. Results: The screening on agar plates with CMC/xylan presented halos of different sizes. From all tested fungi, the best cellulase producer was Malbranchea pulchella, which also Original Research Article