Evaluation of different secretomes produced by Clonostachys byssicola as tools to holocellulose breakdown

Clonostachys byssicola is a filamentous fungus with biotechnological potential for holocellulases production. The present work describes a qualitative and quantitative proteome analysis of C. byssicola secretome cultivated in media supplemented with commercial (Avicel, carboxymethylcellulose or oat spelt xylan) or agricultural (corn cob, soybean hulls, banana stem or sugarcane bagasse) carbon sources. Proteomic data revealed that the fungus produces a common core of lignocellulolytic enzymes when cultivated in different carbon sources. Most of the Carbohydrate-Active Enzymes (CAZymes) identified in the secretomes belong to the families AA9, GH 5, 6, 7, 10 and 43, CE 1, 10 and 12, and PL 1 and 3. Secretomes with the highest specific activity, obtained in corncob, banana stem and sugarcane bagasse, were applied for saccharification of partially delignified corn cob or sugarcane bagasse, and promoted extensive hemicellulose solubilization, with the release of mainly xylobiose. Additionally, the secretomes displayed remarkable differences in the abundance of identified proteins. Considered together, both qualitative and quantitative proteomic characterization presented in this study suggest that C. byssicola produces a similar core of carbohydrases, apparently suitable for the action over a wide range of different lignocellulosic substrates. These findings demonstrate the potential of C. byssicola as a novel source of holocellulases.