Dual roles of capsular extracellular polymeric substances in photocatalytic inactivation of Escherichia coli: Comparison of E. coli BW25113 and isogenic mutants

Loading...
Thumbnail Image
File version

Version of Record (VoR)

Author(s)
Huang, Guocheng
Xia, Dehua
An, Taicheng
Ng, Tsz Wai
Yip, Ho Yin
Li, Guiying
Zhao, Huijun
Wong, Po Keung
Griffith University Author(s)
Primary Supervisor
Other Supervisors
Editor(s)
Date
2015
Size
File type(s)
Location
License
Abstract

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-type Escherichia coli strain BW25113 and isogenic mutants with upregulated and downregulated production of capsular EPS. In a partition system in which direct contact between bacterial cells and TiO2 particles 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 TiO2 particles, 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 TiO2 particles to the cell surface. Fluorescence microscopy and scanning electron microscopy analyses further confirmed that high capsular EPS density led to more TiO2 particles attaching to cells and forming bacterium-TiO2 aggregates. Calculations of interaction energy, represented by extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) potential, suggested that the presence of capsular EPS enhances the attachment of TiO2 particles to bacterial cells via acid-base interactions. Consideration of these mechanisms is critical for understanding bacterium-nanoparticle interactions and the photocatalytic inactivation of bacteria.

Journal Title

Applied and Environmental Microbiology

Conference Title
Book Title
Edition
Volume

81

Issue

15

Thesis Type
Degree Program
School
Publisher link
Patent number
Funder(s)
Grant identifier(s)
Rights Statement
Rights Statement

© 2015 American Society for Microbiology. The attached file is reproduced here in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.

Item Access Status
Note
Access the data
Related item(s)
Subject

Microbiology not elsewhere classified

Persistent link to this record
Citation
Collections