Investigating The Synergistic and Antimicrobial Effect of Glycolipid Biosurfactants Produced by Shewanella alga 12B and Bacillus pumilus SG Bacteria with Thyme Plant Extract on Some Pathogenic Bacteria

Abstract

Background: Thyme is widely recognized for its antimicrobial properties, attributed to the effective compounds present in its extract that inhibit and destroy pathogenic bacteria. Objectives: This study explores the impact of combining thyme extract with biosurfactants on pathogenic bacteria and biofilm. The biosurfactants 12B and SG have inherent antimicrobial effects, and their combination with thyme extract demonstrated synergistic effects. Methods: The experiments involved preparing methanolic thyme extract in combination with biosurfactants 12B and SG. Disk diffusion and well diffusion tests were conducted to assess the antimicrobial activity of this combination. The inhibition zones for Acinetobacterbaumannii, Bacilluscereus, Escherichiacoli, and methicillin-resistant Staphylococcusaureus (MRSA) were measured. Further tests determined the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for these bacteria. To evaluate synergistic effects, the fractional inhibitory concentration (FIC) and fractional inhibitory concentration index (FICI) were calculated. Results: The anti-biofilm effects of the biosurfactants combined with thyme extract were analyzed by testing biofilm formation inhibition, biofilm destruction, and inhibition of dehydrogenase enzyme activity within the biofilm. Biofilm assays were conducted using microplates, with readings taken at 490 nm using an ELISA reader. Conclusions: The biofilm tests demonstrated the effectiveness of thyme extract combined with biosurfactants. The results indicated that this combination exhibits antibacterial, anti-biofilm, and synergistic effects, making it effective against both antibiotic-resistant and non-resistant pathogenic bacteria.