Characterization of Novel Enzymes from Penicillium oxalicum and Their Role in the Degradation of RG-I Pectin

The degradation of complex plant polysaccharides, particularly Rhamnogalacturonan I (RG-I) pectin, is essential for unlocking the value of biomass. This study focuses on the enzymatic toolbox of Penicillium oxalicum for efficient RG-I breakdown. Here, we recombinantly expressed 15 novel pectinolytic enzymes and characterized their biochemical functions. The enzyme system consists of backbone-cleaving rhamnogalacturonan hydrolases and lyases, along with side-chain–degrading enzymes. Specific endo-β-galactanases (GH30, GH43, GH53) and an exo-β-galactosidase (GH35) collaboratively hydrolyze galactan side chains. Meanwhile, α-arabinanases (GH43) and exo-α-arabinofuranosidases (GH54, GH62) work synergistically to degrade arabinan side chains. Through coordinated action, these enzymes achieve complete degradation of complex RG-I structures. Our findings provide a comprehensive enzyme set for targeted polysaccharide deconstruction, offering valuable resources for biomass conversion and pectin valorization in industrial applications.