Biochemical and Structural Characterization of Two-domain Glycoside Hydrolase PgaB from Serratia marcescens and Its Application for S. aureus Biofilm Degradation.

Antimicrobial resistance (AMR) is a critical global health threat, with projections estimating up to 10 million deaths annually by 2050. One of the strategies for developing bacterial AMR is the formation of microbial biofilms (BFs). Thus, enzymes capable of degrading BF exopolysaccharides represent potential tools for BF disruption. In this work, we characterize β-1,6-N-acetylglucosaminidase from Serratia marcescens (SmPgaB), a two-domain enzyme with covalently attached GH153 and CE4 modules. Small-angle scattering data demonstrate that SmPgaB is monomeric in solution. We also demonstrate that SmPgaB degrades Staphylococcus aureus biofilms with up to 92% efficiency and inhibits biofilm formation by over 95%. Furthermore, SmPgaB enhances the effectiveness of gentamicin, tetracycline, and chloramphenicol, reducing the viability of planktonic cells by approximately 50% when used in combination with these antibiotics. Confocal laser scanning microscopy confirmed considerable morphological changes in the biofilm post-treatment. These results showcase the potential of β-1,6-N-acetylglucosaminidases as adjunct therapies for BF-related infections, particularly when combined with conventional antibiotics.