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A New Approach to Detection of the Protective Effect of Escherichia coli on Gram-Positive Bacteria in Binary Biofilms in the Presence of Antibiotics

Authors
  • Plakunov, V. K.
  • Nikolaev, Yu. A.
  • Gannesen, A. V.
  • Chemaeva, D. S.
  • Zhurina, M. V.
Type
Published Article
Journal
Microbiology
Publisher
Pleiades Publishing
Publication Date
May 01, 2019
Volume
88
Issue
3
Pages
275–281
Identifiers
DOI: 10.1134/S0026261719030093
Source
Springer Nature
Keywords
License
Yellow

Abstract

Abstract—Binary biofilms containing gram-positive bacteria Micrococcus thailandicus HB or Kocuria rhizophila strain 4A-2G and gram-negative bacteria Escherichia coli strain K-12 or strain ET12567 pRAG56 were obtained. Strain E. coli ET12567 contained a plasmid encoding aminoglycoside phosphotransferase, the enzyme which inactivates kanamycin. A new kinetic approach was developed for selective detection of metabolically active gram-positive bacteria in binary biofilms with E. coli, based on the differences in reduction rate of the electron acceptor, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). It was found that the studied E. coli strains did not exert a protective effect upon the action of antibiotics vancomycin and oxacillin on gram-positive bacteria in the binary biofilms under formation. However, a protective effect was found in the case of preformed binary biofilms: the growth of gram-positive bacteria in binary biofilms was observed at the concentrations of antibiotics oxacillin and kanamycin, which almost completely suppressed growth in the mono-species biofilms of these gram-positive bacteria. The presence of a protective effect was confirmed by several methods (dynamics of MTT reduction, densitometric evaluation of biofilm staining, measurement of the optical density of MTT extracts, and CFU enumeration).

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