title: Assessment of the in vitro antimicrobial activity of Lactobacillus species for identifying new potential antibiotics.
abstract: The bacteriocin-mediated antimicrobial properties of Lactobacillus spp. have been widely studied, leading to the use of these micro-organisms in the food industry as preservative agents against foodborne pathogens. In an era in which antibiotic resistance is becoming a public health issue, the antimicrobial activity of Lactobacillus spp. could be used for the discovery of new potential antibiotics. Thus, it is essential to have an accurate method of screening the production of antimicrobial agents by prokaryotes. Many in vitro assays have been published to date, largely concerning but not limited to Lactobacillus spp. However, these methods mainly use the spot-on-the-lawn method, which is prone to contamination during the overlay stage, with protocols using methanol vapours or the reverse side agar technique being applied to avoid such contamination. In this study, a method combining the spot-on-the-lawn and well diffusion methods was tested, permitting clear identification of inhibition zones from eight Lactobacillus spp. towards clinical isolates of 12 species (11 bacteria and 1 yeast) commonly found in human pathology. Lactobacillus plantarum CIP 106786 and Lactobacillus rhamnosus CSUR P567 exhibited the widest antimicrobial activity, whereas Lactobacillus acidophilus strain DSM 20079 was relatively inactive. In addition, the putative MIC(50) of L. rhamnosus against Proteus mirabilis was estimated at 1.1×10(9)CFU/mL using culture broth dilution. In conclusion, considering the increasing cultivable bacterial human repertoire, these findings open the way of an effective method to screen in vitro for the production of potential antimicrobial compounds.
authors.affiliation: URMITE, UMR CNRS 6236-IRD 198, Faculté de Médecine, Aix-Marseille Université, 27 Boulevard Jean Moulin, 13385 Marseille Cedex 5, France; IHU Méditerranée Infection, Pôle des Maladies Infectieuses et Tropicales Clinique et Biologique, Fédération de Microbiologie Clinique, AP-HM, CHU Timone, 13005 Marseille, France.
authors.forename: Grégory
authors.initials: G
authors.lastname: Dubourg
authors.affiliation: URMITE, UMR CNRS 6236-IRD 198, Faculté de Médecine, Aix-Marseille Université, 27 Boulevard Jean Moulin, 13385 Marseille Cedex 5, France.
authors.forename: Ziena
authors.initials: Z
authors.lastname: Elsawi
authors.affiliation: URMITE, UMR CNRS 6236-IRD 198, Faculté de Médecine, Aix-Marseille Université, 27 Boulevard Jean Moulin, 13385 Marseille Cedex 5, France; IHU Méditerranée Infection, Pôle des Maladies Infectieuses et Tropicales Clinique et Biologique, Fédération de Microbiologie Clinique, AP-HM, CHU Timone, 13005 Marseille, France. Electronic address: didier.raoult@gmail.com.
authors.forename: Didier
authors.initials: D
authors.lastname: Raoult
mesh_terms: D000890:Anti-Infective Agents / Q000032:analysis*; D001430:Bacteriocins / Q000032:analysis*; D006801:Humans; D007779:Lactobacillus acidophilus / Q000378:metabolism*; D048191:Lactiplantibacillus plantarum / Q000378:metabolism*; D052201:Lacticaseibacillus rhamnosus / Q000378:metabolism*; D008826:Microbial Sensitivity Tests
chemical_list: D000890:Anti-Infective Agents; D001430:Bacteriocins
keywords: Antibiotics; Bacteriocins; In vitro; Lactobacillus; Screening