The inhibitory effect of a Lactobacillus acidophilus derived biosurfactant on Serratia marcescens biofilm formation

Objective(s): Serratia marcescens is one of the nosocomial pathogen. The ability to form biofilm is an important feature in the pathogenesis of S. marcescens. The aim of this study was to determine the anti�adhesive properties of a biosurfactant isolated from Lactobacillus acidophilus ATCC 4356, on S. marcescens strains. Materials and Methods: Lactobacillus acidophilus ATCC 4356, was selected as a probiotic strain to produce biosurfactant. Anti�adhesive activities was determined by pre�coating and co� incubating methods in 96�well culture plates. Results: The FTIR analysis of derived biosurfactant revealed the composition as protein component. Because of the release of such biosurfactants, L. acidophilus was able to interfere with the adhesion and biofilm formation of the S. marcescens strains. In co� incubation method this biosurfactant in 2.5 mg/ml concentration showed anti�adhesive activity against all tested strains of S. marcescens (P<0.05). Conclusion: Our results show anti�adhesive properties of L. acidophilus biosurfactant will be useful against microorganisms responsible for infections in the urinary, vaginal and gastrointestinal tracts, as well as skin, making it a suitable alternative to conventional antibiotics. © 2015, Mashhad University of Medical Sciences. All rights reserved

Antagonistic activities of some probiotic lactobacilli culture supernatant on serratia marcescens swarming motility and antibiotic resistance

Background and Objectives: Serratia marcescens, a potentially pathogenic bacterium, benefits from its swarming motility and resistance to antibiotic as two important virulence factors. Inappropriate use of antibiotics often results in drug resistance phenomenon in bacterial population. Use of probiotic bacteria has been recommended as partial replacement. In this study, we investigated the effects of some lactobacilli culture supernatant on swarming, motility and antibiotic resistance of S. marcescens. Materials and Methods: Antimicrobial activity of lactobacilli supernatant and susceptibility testing carried out on S. marcescens isolates. Pretreatment effect of lactobacilli culture supernatant on antibiotic - resistance pattern in S. marcescens was determined by comparison of the MIC of bacteria before and after the treatment. Results: Our results showed that pretreatment with L. acidophilus ATCC 4356 supernatant can affect the resistance of Serratia strains against ceftriaxone, but it had no effect on the resistance to other antibiotics. Furthermore, culture supernatant of lactobacilli with concentrations greater than 2, had an effect on the swarming ability of S. marcescens ATCC 13880 and inhibited it. Conclusion: Probiotic bacteria and their metabolites have the ability to inhibit virulence factors such as antibiotic resistance and swarming motility and can be used as alternatives to antibiotics. © 2018, Tehran University of Medical Science. All rights reserved

Antimicrobial effect of probiotics in combination with prebiotics against Staphylococcus aureus and Listeria monocytogenes

Background and Objective: Probiotc bacteria have benefical effect on consumer health. This study was done to investigate the antimicrobial effect of several probiotic in combinations with different prebiotics against food patoghenic bacteria including Staphylococcus aureus and Listeria monocytogenes. Methods: In this descriptive - analytical study, probiotics including Lactobacillus plantarum, L. acidophilus, L. fermntum, L. casei and L. rhamnosus with prebiotics (1%) including raffinose, lactulose, inulin and trehalose were cultured in MRS broth for 24 hours at 30ºC in anaerobic conditions. Antimicrobial property of them was determined with well diffusion plate's method. Results: Probiotics in the presence of prebiotics indicated the higher antimicrobial effect compared to probiotics alone (P<0.05). The application of prebiotics such as L. casei with raffinose showed higher antimicrobial property against Listeria monocytogenes than the free prebiotics consumption. The diameter of inhibitory growth zone in the presence of raffinose as a prebiotics was 14.66 mm and its absence reduced to 11.75 mm. Conclusion: Antimicrobial effect of probiotics in combination with prebiotics against Staphylococcus aureus and Listeria monocytogenes was higher than probiotics consumption alone