Characterization of the Extracellular Polymeric Substances Produced by <i>Escherichia coli</i> Using Infrared Spectroscopic, Proteomic, and Aggregation Studies

Eboigbodin, Kevin E.; Biggs, Catherine A.

doi:10.1021/bm701043c

Cited by 206 publications

(171 citation statements)

References 60 publications

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“…Next, the EPS content was evaluated via the sugar/protein ratio so as to compare those for the individually grown E. coli isolate and E. coli grown in the microbial community. The EPS sugar and protein contents were evaluated because they have been reported as indicators of cell conditions (81). It was observed that the sugar/protein ratio was greatly enhanced in the presence of the microbial community (0.10 to 0.23) over that for E. coli O157:H7 in the Haznedaroglu study (0.03) (78).…”

Section: Discussionmentioning

confidence: 99%

Linking Microbial Community Structure to Function in Representative Simulated Systems

Marcus

Wilder

Quazi

et al. 2013

Appl Environ Microbiol

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Pathogenic bacteria are generally studied as a single strain under ideal growing conditions, although these conditions are not the norm in the environments in which pathogens typically proliferate. In this investigation, a representative microbial community along with Escherichia coli O157:H7, a model pathogen, was studied in three environments in which such a pathogen could be found: a human colon, a septic tank, and groundwater. Each of these systems was built in the lab in order to retain the physical/ chemical and microbial complexity of the environments while maintaining control of the feed into the models. The microbial community in the colon was found to have a high percentage of bacteriodetes and firmicutes, while the septic tank and groundwater systems were composed mostly of proteobacteria. The introduction of E. coli O157:H7 into the simulated systems elicited a shift in the structures and phenotypic cell characteristics of the microbial communities. The fate and transport of the microbial community with E. coli O157:H7 were found to be significantly different from those of E. coli O157:H7 studied as a single isolate, suggesting that the behavior of the organism in the environment was different from that previously conceived. The findings in this study clearly suggest that to gain insight into the fate of pathogens, cells should be grown and analyzed under conditions simulating those of the environment in which the pathogens are present.

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Section: Discussionmentioning

confidence: 99%

Linking Microbial Community Structure to Function in Representative Simulated Systems

Marcus

Wilder

Quazi

et al. 2013

Appl Environ Microbiol

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“…However, considerably less is known about the effect of biological factors on photocatalytic inactivation of bacteria. One biological factor that is likely to influence photocatalytic activity is the presence of capsular bacterial extracellular polymeric substances (EPS), which typically comprise polysaccharides and proteins (13).…”

mentioning

confidence: 99%

“…Located at or outside the cell surface, EPS have many functions, including facilitating bacterial adhesion, providing a protective barrier against environmental stresses, maintaining hydration, and storing nutrients (13). The protective function has been reported to significantly increase bacterial tolerance to antibiotics and disinfectants both by limiting the transport of biocides and via a direct reaction with the EPS (14,15).…”

mentioning

confidence: 99%

Dual Roles of Capsular Extracellular Polymeric Substances in Photocatalytic Inactivation of Escherichia coli: Comparison of E. coli BW25113 and Isogenic Mutants

Huang

Xia

et al. 2015

Appl Environ Microbiol

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The dual roles of capsular extracellular polymeric substances (EPS) in the photocatalytic inactivation of bacteria were demonstrated in a TiO2-UVA system, by comparing wild-typeEscherichia colistrain BW25113 and isogenic mutants with upregulated and downregulated production of capsular EPS. In a partition system in which direct contact between bacterial cells and TiO2particles was inhibited, an increase in the amount of EPS was associated with increased bacterial resistance to photocatalytic inactivation. In contrast, when bacterial cells were in direct contact with TiO2particles, an increase in the amount of capsular EPS decreased cell viability during photocatalytic treatment. Taken together, these results suggest that although capsular EPS can protect bacterial cells by consuming photogenerated reactive species, it also facilitates photocatalytic inactivation of bacteria by promoting the adhesion of TiO2particles to the cell surface. Fluorescence microscopy and scanning electron microscopy analyses further confirmed that high capsular EPS density led to more TiO2particles attaching to cells and forming bacterium-TiO2aggregates. Calculations of interaction energy, represented by extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) potential, suggested that the presence of capsular EPS enhances the attachment of TiO2particles to bacterial cells via acid-base interactions. Consideration of these mechanisms is critical for understanding bacterium-nanoparticle interactions and the photocatalytic inactivation of bacteria.

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“…Cell sedimentation assay. The cell sedimentation rate was quantified using the assay described by Eboigbodin and Biggs (25) and Fu et al (26). Cells were grown in YPD liquid medium with or without 0.1 g/ml doxycycline (for transcriptional repression) and 2.5 mM L-cysteine or ascorbic acid.…”

Section: Methodsmentioning

confidence: 99%

Ascorbic Acid Inhibition of Candida albicans Hsp90-Mediated Morphogenesis Occurs via the Transcriptional Regulator Upc2

2014

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Morphogenetic transitions of the opportunistic fungal pathogen Candida albicans are influenced by temperature changes, with induction of filamentation upon a shift from 30 to 37°C. Hsp90 was identified as a major repressor of an elongated cell morphology at low temperatures, as treatment with specific inhibitors of Hsp90 results in elongated growth forms at 30°C. Elongated growth resulting from a compromised Hsp90 is considered neither hyphal nor pseudohyphal growth. It has been reported that ascorbic acid (vitamin C) interferes with the yeast-to-hypha transition in C. albicans. In the present study, we show that ascorbic acid also antagonizes the morphogenetic change caused by hampered Hsp90 function. Further analysis revealed that Upc2, a transcriptional regulator of genes involved in ergosterol biosynthesis, and Erg11, the target of azole antifungals, whose expression is in turn regulated by Upc2, are required for this antagonism. Ergosterol levels correlate with elongated growth and are reduced in cells treated with the Hsp90 inhibitor geldanamycin (GdA) and restored by cotreatment with ascorbic acid. In addition, we show that Upc2 appears to be required for ascorbic acid-mediated inhibition of the antifungal activity of fluconazole. These results identify Upc2 as a major regulator of ascorbic acid-induced effects in C. albicans and suggest an association between ergosterol content and elongated growth upon Hsp90 compromise.

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Characterization of the Extracellular Polymeric Substances Produced by Escherichia coli Using Infrared Spectroscopic, Proteomic, and Aggregation Studies

Cited by 206 publications

References 60 publications

Linking Microbial Community Structure to Function in Representative Simulated Systems

Linking Microbial Community Structure to Function in Representative Simulated Systems

Dual Roles of Capsular Extracellular Polymeric Substances in Photocatalytic Inactivation of Escherichia coli: Comparison of E. coli BW25113 and Isogenic Mutants

Ascorbic Acid Inhibition of Candida albicans Hsp90-Mediated Morphogenesis Occurs via the Transcriptional Regulator Upc2

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