Phylogeny-guided identification of a 1-kestose-degrading GH32 from fish-derived Clostridium butyricum LZK-08, with exploratory survival observations during natural infectious hematopoietic necrosis exposure in rainbow trout

Abstract Dietary 1-kestose in rainbow trout was associated with higher Clostridiaceae abundance and descriptively higher survival during natural infectious hematopoietic necrosis exposure. To explore a possible microbial basis, we examined GH32 enzymes from fish-derived probiotic Clostridium butyricum LZK-08. Phylogeny-guided testing of E. coli-expressed GH32s identified plasmid-encoded LZK-GH32-2 (XTP15357.1) as a 1-kestose-degrading enzyme, suggesting strain-specific GH32 repertoires may underlie selective prebiotic responses.