Evaluation of the Antibacterial Effects of Surfactin Peptide and its Application in a Topical Gel Formulation

Abstract

 Abstract

The escalating issue of antibiotic resistance necessitates the development of novel antimicrobial agents. Surfactin, a cyclic lipopeptide produced by Bacillus subtilis, has demonstrated promising biological activities, including antibacterial properties. This study aimed to evaluate the efficacy of surfactin peptide against a panel of pathogenic bacteria and to develop a topical gel formulation based on it for ease of application. The antibacterial activity of surfactin was assessed using hemolysis assays, well agar diffusion tests, minimum inhibitory concentration (MIC) assays, and minimum bactericidal concentration (MBC) assessments. A 2.5% w/v surfactin gel was formulated and its thermal stability and in vitro antibacterial efficacy against Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa were  

evaluated over a one-month period. Results indicated that surfactin at 0.1% did not cause hemolysis, while higher concentrations (2.5%) did. In agar

diffusion and MIC assays, surfactin exhibited inhibitory activity against S. aureus and S. epidermidis at concentrations of 1.25% and 2.5%, but showed no significant effect on P. aeruginosa. The formulated gel demonstrated stable physical characteristics (pH and viscosity) and retained its antibacterial activity against S. aureus and S. epidermidis over one month at different storage temperatures, while remaining ineffective against P. aeruginosa. Furthermore, the gel showed a reduction in bacterial growth from a nail swab sample. These findings suggest that a 2.5% surfactin gel has potential as a topical antibacterial agent, particularly against skin infections caused by S. aureus and S. epidermidis. Further in vivo studies and detailed mechanism of action investigations are warranted.

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