“Essential oil intervention: The antimicrobial and antibiofilm properties of clove oil and Eugenol against vibrio cholerae O1”

Abstract

Vibrio cholerae O1, the causative agent of cholera, is a gram-negative bacterium transmitted through contaminated food and water, particularly in areas with poor sanitation. Its ability to form biofilms enhances survival, colonization, and resistance, posing a significant challenge in managing infections. As conventional antimicrobials lose efficacy, essential oils with diverse bioactive compounds, such as Syzygium aromaticum (clove oil) and its major component eugenol, offer promising alternatives. This study evaluates the antimicrobial and anti-biofilm properties of clove oil and its major component eugenol against V. cholerae O1 using various assays, including broth microdilution, biofilm inhibition, EPS reduction, membrane integrity and Biofilm gene expression. Along with potent anti-microbial activity, both agents effectively inhibited biofilm formation and disrupted pre-formed biofilms. Gene expression analysis revealed a concentration-dependent upregulation of biofilm-related genes vpsA and rbmA at sub-inhibitory levels. like, clove oil at MIC/2 induced an 8-fold increase in vpsA and a 6-fold increase in rbmA, reflecting a bacterial stress response to sub-lethal antimicrobial exposure. However, at MIC concentrations, these agents exhibited rapid bactericidal effects, leaving no viable cells for gene expression analysis. The findings underscore the dual role of clove oil and eugenol: while potent in eliminating bacteria at inhibitory concentrations, they also elicit biofilm-related survival mechanisms at sub-lethal doses, a phenomenon documented in prior studies with other antimicrobials. Understanding these stress-response mechanisms provides insights into optimizing therapeutic strategies for biofilm-associated infections. These results position Syzygium aromaticum and eugenol as potential alternatives to combat antimicrobial resistance, advancing the application of natural products in clinical and public health settings.