Pediococcus acidilactici JUFB as a probiotic antibiofilm adjunct against Enterococcus faecalis in persistent endodontic infections.

Enterococcus faecalis remains a primary cause of persistent endodontic infections, persisting in root canals through robust biofilm formation and antimicrobial resistance. This study characterized clinical E. faecalis oral isolates and evaluated the comparative efficacy of conventional endodontic medicaments against the probiotic and antibiofilm potential of food derived Lactic Acid Bacteria (LAB). Clinical isolates (JUDS 01, JUDS 02, JUDS 03, JUSA 05) exhibited a high prevalence of ace, agg, cyl, and gelE virulence genes, demonstrating significant multidrug resistance. Among conventional treatments, TAP exhibited the notable antibacterial zones of inhibition (23 ± 1-24 ± 0.5 mm) and uniform, highly significant biomass reduction (p < 0.0001), whereas Ca(OH)2, NaOCl, and DAP completely failed to reduce mature biofilms (p > 0.05). Among the probiotic strains, Pediococcus acidilactici JUFB demonstrated great physiological stress tolerance, maintaining robust survival under lethal acid conditions (OD600 = 0.32 at pH 2.0) and high growth under bile stress (OD600 = 1.15 in 0.3% Oxgall). Remarkably, organic extracts of P. acidilactici JUFB achieved a maximum of up to 70% relative reduction in mature E. faecalis biofilm biomass (p < 0.0001) at 0.12 mg/ml optimal concentration, overcoming P. acidilactici JUFF and Streptococcus thermophilus JUBM. GC-MS analysis of this active extract identified unique peaks, prioritizing core functional micro metabolites including carbamimidoyl sulfanyl acetic acid and 2-ethyl-2-methyl-1,3-propanediol as putative antibiofilm agents. These findings indicate that while TAP remains a potent conventional therapy, P. acidilactici JUFB possesses higher probiotic attributes and powerful antibiofilm activity, supporting its use as a resistance mitigating therapeutic alternative.