IMR Press / FBL / Volume 29 / Issue 5 / DOI: 10.31083/j.fbl2905171
Open Access Original Research
Enhancing the Antibacterial Impact of Lipopeptide Extracted from Bacillus licheniformis as a Probiotic against MDR Acinetobacter baumannii
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1 Department of Laboratory Sciences, Faculty of Paramedical and Rehabilitation Sciences, Mashhad University of Medical Sciences, 91779-48564 Mashhad, Iran
2 Department of Microbiology, Faculty of Basic Sciences, Qom Branch, Islamic Azad University, 3749113191 Qom, Iran
3 Department of Microbiology, Faculty of Basic Sciences, Arak Branch, Islamic Azad University, 3836119131 Arak, Iran
*Correspondence: r.nazari1102002@gmail.com (Razieh Nazari)
These authors contributed equally.
Front. Biosci. (Landmark Ed) 2024, 29(5), 171; https://doi.org/10.31083/j.fbl2905171
Submitted: 31 October 2023 | Revised: 21 February 2024 | Accepted: 19 March 2024 | Published: 30 April 2024
Copyright: © 2024 The Author(s). Published by IMR Press.
This is an open access article under the CC BY 4.0 license.
Abstract

Background: The antibiotic resistance of microorganisms is escalating rapidly. Infections caused by opportunistic pathogens in immunocompromised individuals have prompted researchers to seek for potent and safe antibacterial agents. The purpose of this investigation was to explore the suppression of virulence gene expression, specifically the pga operon genes responsible in biofilm formation in Acinetobacter baumannii, through the utilization of metabolites obtained from probiotic bacteria. Methods: To assess the antimicrobial properties, standard strains of five probiotic bacteria were tested against a standard strain of multidrug-resistant (MDR) A. baumannii employing the agar gel diffusion technique. Following the identification of the most potent probiotic strain (Bacillus licheniformis), the existence of its LanA and LanM genes was confirmed using the polymerase chain reaction (PCR) test. High-performance liquid chromatography (HPLC) and fourier-transform infrared spectroscopy (FTIR) techniques were employed to identify the intended metabolite, which was found to be a lipopeptide nature. The minimum inhibitory concentration (MIC) values and anti-biofilm activity of the targeted metabolite were determined using a dilution method in 96-well microplates and field emission scanning electron microscopy (FE-SEM). Real-time PCR (qPCR) was utilized for comparing the expression of pga operon genes, including pgaABCD, in A. baumannii pre- and post-exposure to the derived lipopeptide. Results: The MIC results indicated that the probiotic product inhibited the growth of A. baumannii at concentrations lower than those needed for conventional antibiotics. Furthermore, it was observed that the desired genes’ expression decreased due to the effect of this substance. Conclusions: This research concludes that the B. licheniformis probiotic product could be a viable alternative for combating drug resistance in A. baumannii.

Keywords
probiotics
drug resistance
Acinetobacter baumannii
pga operon genes
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