title: The Inhibition Effect of Lactobacilli Against Growth and Biofilm Formation of Pseudomonas aeruginosa.
abstract: The emergence of antibiotic-resistant and food-spoilage microorganisms has renewed efforts to identify safe and natural alternative agents of antibiotics such as probiotics. The aim of this study was the isolation of lactobacilli as potential probiotics from local dairy products with broad antibacterial and anti-biofilm activities against antibiotic-resistant strains of Pseudomonas aeruginosa and determination of their inhibition mechanism. Antibiotic susceptibility and classification of acquired resistance profiles of 80 P. aeruginosa strains were determined based on Centers for Disease Control and Prevention (CDC) new definition as multidrug-resistant (MDR), extensively drug-resistant (XDR), and pan-drug-resistant (PDR) followed by antibacterial assessment of lactobacilli against them by different methods. Among the 80 P. aeruginosa strains, 1 (1.3%), 50 (62.5%), and 78 (97.5%) were PDR, XDR, and MDR, respectively, and effective antibiotics against them were fosfomycin and polymyxins. Among 57 isolated lactobacillus strains, two strains which were identified as Lactobacillus fermentum using biochemical and 16S rDNA methods showed broad inhibition/killing and anti-biofilm effects against all P. aeruginosa strains. They formed strong biofilms and had bile salts and low pH tolerance. Although investigation of inhibition mechanism of these strains showed no bacteriocin production, results obtained by high-performance liquid chromatography (HPLC) analysis indicated that their inhibitory effect was the result of production of three main organic acids including lactic acid, acetic acid, and formic acid. Considering the broad activity of these two L. fermentum strains, they can potentially be used in bio-control of drug-resistant strains of P. aeruginosa.
authors.affiliation: Department of Biology, Faculty of Sciences, University of Isfahan, Hezar Jarib Street, Isfahan, Iran.
authors.forename: Dariush
authors.initials: D
authors.lastname: Shokri
authors.affiliation: Department of Biology, Faculty of Sciences, University of Isfahan, Hezar Jarib Street, Isfahan, Iran. m.rabbani@biol.ui.ac.ir.
authors.forename: Mohammad Rabbani
authors.initials: MR
authors.lastname: Khorasgani
authors.affiliation: Department of Pharmaceutical Biotechnology and Pharmaceutical Sciences Research Center, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Milad
authors.initials: M
authors.lastname: Mohkam
authors.affiliation: Faculty of Basic Sciences, Department of Microbiology, Islamic Azad University, Shahrekord Branch, Shahrekord, Iran.
authors.forename: Seyed Masih
authors.initials: SM
authors.lastname: Fatemi
authors.affiliation: Department of Pharmaceutical Biotechnology and Pharmaceutical Sciences Research Center, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Younes
authors.initials: Y
authors.lastname: Ghasemi
authors.affiliation: Department of Biotechnology, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan, Iran.
authors.forename: Asghar
authors.initials: A
authors.lastname: Taheri-Kafrani
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000898:Antibiosis; D001430:Bacteriocins / Q000096:biosynthesis; D018441:Biofilms / Q000187:drug effects; D024901:Drug Resistance, Multiple, Bacterial; D007778:Lactobacillus / Q000235:genetics / Q000502:physiology*; D008826:Microbial Sensitivity Tests; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins
keywords: Antibiotic resistance; Lactobacilli; Multidrug-resistant (MDR); Probiotic; Pseudomonas aeruginosa