Optimization of the purification process and characterization of natural variants and truncated forms of enterocin L50A/L50B from Enterococcus durans LC2 with antibacterial activity

Abstract Aims The rise of multidrug-resistant (MDR) pathogens has driven interest in bacteriocins as alternative antimicrobial agents. This study aimed to isolate bacteriocin-producing lactic acid bacteria from traditional Moroccan foods, purify their active compounds, and assess their activity against MDR clinical isolates. Methods and Results Enterococcus durans LC2, isolated from camel milk, was found to produce four bacteriocins (B1, B2, C1, C2). Initial purification using a C18 reversed-phase HPLC column yielded partially overlapping peaks; to improve separation, a phenyl-hexyl column was introduced as a second-stage refinement. Four active fractions were isolated and characterized using mass spectrometry and Edman degradation. B1 and B2 were identified as modified forms of enterocin L50A/B, while C1 and C2 were novel truncated variants. Antimicrobial testing revealed limited activity for B1 and B2, but strong synergistic effects of C1 and C2, particularly against Acinetobacter baumannii and Enterococcus faecalis. Conclusion Structurally modified enterocins C1 and C2 show promising synergistic activity against MDR pathogens, highlighting their potential as alternative therapeutic agents in the fight against antimicrobial resistance.