Synergistic Biofilm Inhibition and Eradication by Combined Garlic and Lantana camara Linn Extracts in Cooling Water Systems

Abstract

Controlling biofilms presents a major environmental and economic challenge in cooling water systems, primarily due to biofilm-induced corrosion. This study assesses a green, plant-based alternative: a combination of Lantana camara Linn and Allium sativum (garlic) extracts for inhibiting and eradicating biofilms and corrosion on mild steel. The treatment showed high efficacy, achieving 91.54% inhibition and 74.65% eradication of preformed biofilms. Moreover, it decreased the corrosion rate by 87.47% in preventive applications and 69.87% in eradication scenarios. Mechanistic studies revealed that the extract combination disrupted biofilm development by suppressing bacterial metabolic activity and inhibiting the production of extracellular polymeric substances (EPS) and proteins. It also reduced initial cell adhesion and altered the surface hydrophobicity of mild steel. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) confirmed a significant reduction in biofilm thickness and cell density. Fourier-transform infrared (FTIR) spectroscopy verified the adsorption of the extracts onto the metal surfaces, establishing a protective barrier that shields the steel from corrosive agents. These findings highlight the strong potential of the Lantana-garlic extract formulation as an effective and sustainable strategy for biofilm and corrosion mitigation in industrial cooling water systems.