Alkaline cellulase producing fungi were isolated from soils of an undisturbed rain forest of Peru. The soil dilution plate method was used for the enumeration and isolation of fast growing cellulolytic fungi on an enriched selective medium. Eleven out of 50 different morphological colonies were finally selected by using the plate clearing assay with CMC as substrate at different pH values. All 11 strains produced cellulases in liquid culture with activities at alkaline pH values without an apparent decrease of them indicating that they are true alkaline cellulase producers. Aspergillus sp. LM-HP32, Penicillium sp. LM-HP33, and Penicillium sp. LM-HP37 were the best producers of FP cellulase (>3？U？mL？1) with higher specific productivities (>30？U？g？1？h？1). Three strains have been found suitable for developing processes for alkaline cellulase production. Soils from Amazonian rain forests are good sources of industrial fungi with particular characteristics. The results of the present study are of commercial and biological interest. Alkaline cellulases may be used in the polishing and washing of denim processing of the textile industry. 1. Introduction Plant biomass is one of the most abundant renewable resources for many purposes, and it is mainly composed of three types of polymers: cellulose, hemicellulose, and lignin that are strongly intermeshed and chemically bonded by noncovalent forces and by covalent cross-linkages. The rigid and complex molecular polymeric structure of cellulosic biomass makes lignocellulose highly resistant to chemical attack, solubilisation, and bioconversion. Physical or chemical pretreatment procedures which break down the lignocellulosic structures and thereby enhance the enzymatic accessibility are required for the conversion of biomass into several possible bioproducts [1, 2]. The enzymatic hydrolysis of cellulose materials involves synergistic actions of cellulases as well as xylanases and other enzymes [3, 4]. Cellulases are relatively costly enzymes, and a significant reduction in cost will be important for their commercial use. Most industrial cellulases are produced by fungi in submerged fermentation. Trichoderma reesei is the most important fungal species used for cellulase production although it produces low levels of β-glucosidase [5]. Some Aspergillus species are also important cellulase producers with higher levels of β-glucosidase than T. reesei [6]. The use of enzymes for processing cotton fiber in replacement of chemical and physical methods such as the use of alkali and washing with stones is relatively recent
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