Thymus zygis essential oil-loaded bacterial cellulose as an antimicrobial and antibiofilm biomaterial: an in vitro study

Abstract Bacterial cellulose (BC) is a promising biomaterial for biomedical applications, but its lack of intrinsic antimicrobial activity limits its use in infection-prone environments. This study evaluated the antimicrobial and antibiofilm activities of Salvia sclarea essential oil (Ss EO) and Thymus zygis essential oil (Tz EO) against Candida tropicalis T26, Proteus mirabilis U15, and Staphylococcus epidermidis W17, and investigated the antimicrobial and antibiofilm properties of Tz EO-loaded BC. Antimicrobial activity was assessed by broth microdilution and disc diffusion assays, whereas antibiofilm activity was determined using the crystal violet assay. Microbial colonization on BC discs was examined by scanning electron microscopy (SEM) coupled with energy-dispersive X-ray (EDX) analysis. Tz EO exhibited greater antimicrobial activity than Ss EO, with lower minimum inhibitory and microbicidal concentrations and larger inhibition zones. Notably, BC loaded with only 0.25% (v/v) Tz EO (2.5 µL/mL) inhibited the growth of all tested isolates, whereas BC containing Tz EO at 0.25×MIC reduced biofilm formation by more than 91% across all tested isolates. SEM observations, supported by EDX analysis, indicated reduced microbial colonization on Tz EO-loaded BC discs. These findings support the potential of Tz EO-loaded BC as an antimicrobial biomaterial with broad-spectrum antimicrobial and antibiofilm activity and warrant further evaluation for applications aimed at limiting biofilm-associated infections.