A Cellulolytic Streptomyces Sp. Isolated from a Highly Oligotrophic Niche Shows Potential for Hydrolyzing Agricultural Wastes

Cellulases from Streptomyces species can be used as auxiliary agents in the pretreatment of lignocellulosic materials, but little work has been done on this topic. Besides, Streptomyces strains have been identified from Cuatro Cienegas basin, but their potential in the treatment of agricultural wastes has not been demonstrated. In this work a Streptomyces sp., strain CC48 isolated from the oligotrophic environment, shows high levels of cellulolytic activity (0.76 U/ mL at pH 7.0, 60 °C) in minimum medium supplemented with carboxymethyl cellulose compared with other Streptomyces strains and isolates in a bacterial collection. At least three putative cellulases (~30, 40, and 45 kDa) were identified in Streptomyces sp. CC48 extracts. The addition of Mg 2+ increased cellulase activity by 23%, whereas other cations resulted in decreased catalysis. Residual cellulolytic activities after 4 and 8 h of incubation at 60 °C were ~ 73 and 65%, respectively, and ~ 98% at 50 °C after 8 h. Corn cob and wheat straw pretreated with an alkaline method showed saccharification values of 320 and 330 mg/g of reducing sugars per gram of dry substrate, respectively. The significance of this work lies in the fact that data provided here show that Streptomyces sp. strain CC48 is capable of hydrolyzing both maize and wheat substrates, suggesting the potential of this bacterium to hydrolyze agricultural wastes. Also, Cuatro Cienegas Basin may represent a source for efficient cellulolytic microorganisms.