Surface films of Escherichia coli colonies

Tetz, Victor

doi:10.1016/0378-1097(93)90315-s

Cited by 8 publications

(16 citation statements)

References 8 publications

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“…It is required that the rate of bleb production during exponential growth be proportional to wall turnover and synthesis and to assembly of outer membrane. The presence of membrane vesicles in bacterial colonies has been reported [23]. The bacteria in developed colonies are mixtures of dead cells, division‐arrested cells and actively dividing cells.…”

Section: Resultsmentioning

confidence: 94%

On the origin of membrane vesicles in Gram-negative bacteria

Zhou

Srisatjaluk

Justus

et al. 1998

FEMS Microbiology Letters

193

131

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Section: Resultsmentioning

confidence: 94%

On the origin of membrane vesicles in Gram-negative bacteria

Zhou

Srisatjaluk

Justus

et al. 1998

FEMS Microbiology Letters

193

131

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“…Other studies have shown that at later stages of colony development (20 to 24 h), the surface film of E. coli colonies became thicker. On the other hand, the film was not observed for colonies cultured for 6 to 16 h of growth (45)(46)(47)(48). Therefore, it is possible that the glycogen-rich surface layer observed with Raman microspectroscopy is the polysaccharide-rich extracellular coat, commonly known as the glycocalyx, of bacterial cells.…”

Section: Resultsmentioning

confidence: 99%

Investigating Microbial (Micro)colony Heterogeneity by Vibrational Spectroscopy

Choo-Smith

Maquelin

Vreeswijk

et al. 2001

Appl Environ Microbiol

233

160

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Fourier transform infrared and Raman microspectroscopy are currently being developed as new methods for the rapid identification of clinically relevant microorganisms. These methods involve measuring spectra from microcolonies which have been cultured for as little as 6 h, followed by the nonsubjective identification of microorganisms through the use of multivariate statistical analyses. To examine the biological heterogeneity of microorganism growth which is reflected in the spectra, measurements were acquired from various positions within (micro)colonies cultured for 6, 12, and 24 h. The studies reveal that there is little spectral variance in 6-h microcolonies. In contrast, the 12-and 24-h cultures exhibited a significant amount of heterogeneity. Hierarchical cluster analysis of the spectra from the various positions and depths reveals the presence of different layers in the colonies. Further analysis indicates that spectra acquired from the surface of the colonies exhibit higher levels of glycogen than do the deeper layers of the colony. Additionally, the spectra from the deeper layers present with higher RNA levels than the surface layers. Therefore, the 6-h colonies with their limited heterogeneity are more suitable for inclusion in a spectral database to be used for classification purposes. These results also demonstrate that vibrational spectroscopic techniques can be useful tools for studying the nature of colony development and biofilm formation.In recent years, there has been much effort invested into the development of new techniques for the identification of microorganisms. Many of these methods are aimed at providing the clinician with more rapid identification of the microorganism responsible for infection in order to begin the appropriate course of antimicrobial treatment (1,9,15,21,27,31,44,51). The emergence of these novel methods reflects the rise in drug-resistant microorganisms, which requires that antimicrobial treatment be more effectively managed (2, 12, 28, 52). Among the new methods are those based on vibrational spectroscopic techniques, namely Fourier transform infrared (FT-IR) and Raman spectroscopies. Vibrational spectroscopic methods are reagentless procedures in which there is no need to add dyes or labels for spectral measurement. These nondestructive techniques are based on the absorption (FT-IR) or scattering (Raman) of light directed onto a sample. The amount of light absorbed or scattered depends on the molecules found within the sample and the environment in which these molecules are found. With these highly sensitive techniques, the frequency of light in the resulting spectrum provides biochemical information regarding the molecular composition and molecular structure of and molecular interaction in cells and tissues (24,55). Raman and infrared spectroscopies are complementary techniques which together can provide a more complete impression of the biochemical information within a sample. Furthermore, these two methods differ such that each is capable of providing informatio...

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“…It was shown that the extracellular DNA in the biofilm matrix could take part in the development of bacterial communities (25,40,49,63). It can be released by live cells, possibly via membrane vesicles composed of bacterial lipids (65), or it may enter the matrix from lysed cells (10,18,19,48,58,65). We have recently found cell-free DNA as a component of EPS in biofilms formed by various unrelated gram-positive and gramnegative bacteria and fungi (G. Tetz and V. Tetz, unpublished data).…”

mentioning

confidence: 99%

Effect of DNase and Antibiotics on Biofilm Characteristics

Tetz

Artemenko

Tetz

2009

Antimicrob Agents Chemother

341

247

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The role of extracellular DNA in the maintenance of biofilms formed by gram-positive and gram-negative bacteria was studied. This study evaluated all the bacterial strains that were tested for the presence of extracellular DNA with an average size of 30 kb in the matrix. Our results indicate changes in community biomass, architecture, morphology, and the numbers of CFU in the presence of DNase. This effect seems to be common to biofilms established by various unrelated gram-positive and gram-negative bacteria. The cleavage of extracellular DNA leads to the formation of an altered biofilm that permits the increased penetration of antibiotics. Thus, the addition of DNase enhances the effect of antibiotics, resulting in decreased biofilm biomass and numbers of CFU.It is well known that bacteria form biofilms, in which they survive in the presence of high concentrations of antimicrobial agents (13,23,28,51,52,55). Antibiotics at concentrations of 10 2 to 10 4 times the MIC cause no killing effect on the bacteria in biofilm communities (2,7,14,22,24,32,54). Bacterial survival in biofilms may be determined by multiple different factors. Biofilms are covered by a surface film composed of lipid components similar to those in bacterial membranes, which are a barrier for the penetration of some antibiotics (57, 59). The roles of separate components of the biofilm matrix in the bacterial life have recently been studied (17,26,50,63). It is known that the matrix consists of proteins, polysaccharides, lipids, and nucleic acids, which form an extracellular polymeric substance (EPS) (21,34,56,64). Some suggest that EPS can interact with antibiotics in a manner that leads to a decline in antibacterial activity (5,8,29). It was also shown that bacterial survival in biofilms in the presence of antibiotics can be determined by special cells persisters, which are tolerant to various drugs (27,31,35,51). Recently, extracellular DNA has been found in the matrix of Pseudomonas aeruginosa and Neisseria gonorrhoeae biofilms (1,26,32,50,63). Previously, free circulating DNA was found in human blood plasma (3,45,61), and it is also present in marine sediments and soil (6,15,16,44,60). It was shown that the extracellular DNA in the biofilm matrix could take part in the development of bacterial communities (25,40,49,63). It can be released by live cells, possibly via membrane vesicles composed of bacterial lipids (65), or it may enter the matrix from lysed cells (10,18,19,48,58,65). We have recently found cell-free DNA as a component of EPS in biofilms formed by various unrelated gram-positive and gramnegative bacteria and fungi (G. Tetz and V. Tetz, unpublished data). It was previously shown that the destruction of the extracellular DNA of P. aeruginosa and Streptococcus pneumoniae could change the properties of the biofilms formed by these bacteria (30,40,63). At the same time, this phenomenon has not been studied with other microorganisms. The role of extracellular DNA in the interaction of bacterial biofilms with environmental factors i...

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Surface films of Escherichia coli colonies

Cited by 8 publications

References 8 publications

On the origin of membrane vesicles in Gram-negative bacteria

On the origin of membrane vesicles in Gram-negative bacteria

Investigating Microbial (Micro)colony Heterogeneity by Vibrational Spectroscopy

Effect of DNase and Antibiotics on Biofilm Characteristics

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