Zaporožskij Medicinskij Žurnal (Aug 2020)
Antimicrobial activity of structural-metabolic complexes of L. rhamnosus GG and S. boulardii against S. aureus AТСС 25923, E. coli ATCC 25922, Р. аеruginosa ATCC 27853
Abstract
The aim of the work – to determine the sensitivity of reference strains to structural-metabolic complexes of both Lactobacillus rhamnosus GG alone and in combination with Saccharomyces boulardii to justify the possibility of developing antimicrobial drugs with polyfunctional activity. Materials and methods. Proprietary structural-metabolic complexes of lactobacteria and lactobacteria with saccharomycetes were obtained without the use of culture media. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined by the serial dilution micromethod in a culture medium in a 96-well plate. To estimate the MIC, the optical density of the samples was spectrophotometrically measured using a Lisa ScanTM EM analyzer (Erba Mannheim, Czech Republic), and broth was plated on a solid culture medium for the MBC estimation. The concentrations of the test substances ranged from 1.10 to 0.02 mg/ml by the total protein. The test cultures were reference strains of S. aureus ATCC 25923, E. coli ATCC 25922, P. aeroginosa ATCC 27853. Results. The antimicrobial effect was found to be in direct proportion to the exposure time, concentration and activity of structural-metabolic complexes of lactobacteria and lactobacteria with saccharomycetes. The MBC of lactobacteria filtrates for S. aureus ATCC 25923, E. coli ATCC 25922, P. aeruginosa ATCC 27853 was 0.27 mg/ml by protein, and lactobacteria and saccharomycetes – 0.21 mg/ml by protein. The structural-metabolitic complex of Lactobacillus with a concentration of 0.14 mg/ml by protein also presented bactericidal effect on the culture of P. aeruginosa ATCC 27853. The lowest tested concentrations of the studied Lactobacillus rhamnosus GG (0.03 mg/ml by protein) filtrates and combinations with Saccharomyces boulardii (0.02 mg/ml by protein) caused a decrease in the optical density of the reference strains of S. aureus ATCC 25923, E. coli ATCC 25922, P. aeruginosa ATCC 27853 by 77.16–82.30 %, 51.25 – 52.78 %, 31.43–31.58 % (P ≤ 0.01), respectively. The MICs values corresponded to the MBCs. Conclusions. As a result of the studies, the sensitivity of S. aureus ATCC 25923, E. coli ATCC 25922, and P. aeruginosa ATCC 27853strains to both structural-metabolic complexes of lactobacteria and saccharomycetes was determined. The obtained minimum inhibitory/bactericidal concentrations of the studied filtrates of L. rhamnosus GG and S. boulardii will be useful in the development of promising antimicrobial agents for alternative or add-on therapies of diseases having various origins.
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