Carbohydrate Active enZYmes: functional study and applicative perspectives

Carbohydrates play an important role in a variety of biological and industrial process. The numerous combinatorial possibilities of glycan building blocks explains the variety of competing and sequentially acting enzymatic activies involved in their modification, such as glycosidases, glycosyltransferases and esterases. These enzymes build, modify, and hydrolyze complex carbohydrates and glycoconjugates addressing a large body of biological roles. The discovery of novel thermophilic carbohydrate active enzymes can help us to understand the functional involvement of this class of enzymes in various biological phenomena and how we can exploit their “eco-friendly” activities in numerous industrial processes. This thesis work is dedicated to the study of thermophilic CAZymes and can be subdivided in three principal sections. The first section is focused on the identification of novel thermophilic glycosidases selected in sequence database. Since sustainable biorefineries require numerous biocatalysts, the research topic was addressed at the identification of new thermostable hemicellulases that can be used in the production of second generation bioethanol. The search of novel thermostable enzymes led us to sequence metagenomic DNA isolated from a solfataric field Pisciarelli. In this context, the changes of microbiome colonizing this enviroment in relation to geothermal variations were explored, as described in the second sections. This study allowed to increase our knowledge on habitats with high selective pressure. In the third section, novel cazyme from crenarchaeon S. solfataricus P2 was identified by functional screening. This study led us to achieve additional data concerning the set of cazymes present in S. solfataricus allowing to identification of a novel unclassified enzyme.