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EMSL Project ID


Usage of advanced instrumentation available in the EMSL is requested to perform rigorous and systematic characterization of extracellular polymeric substances (EPS) secreted by bacteria. A comprehensive identification of proteins, polysaccharides, and (phosphor)lipids present in extracellular polymeric substances is necessary for a molecular level understanding of biofilm formation in numerous natural and technological systems.

The specific objectives of the proposed research are to (1) quantify short- term bacterial membrane fouling mechanisms, (2) establish the role of bacterial secretions of EPS in long-term fouling, (3) comprehensively characterize extracellular polymeric substances using state-of-the-art instrumentation, and (4) quantify the efficacy of several bismuth thiols to suppress bacterial expression of extracellular polymeric substances and therefore mitigate fouling.

Two Gram negative bacteria, Serratia marcescens and Escherichia coli will be used as model organisms. The elemental composition and chemical functionality of free and cell-bound EPS will be measured using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning auger microscopy. A particularly innovative aspect of this proposal is that several anti-fouling agents capable of suppressing extracellular polymeric substances expression at very low (micro-molar) concentrations will be evaluated. The proposed research will substantially advance our understanding of bacterial interactions with surfaces (including filters used for water purification) and lay the groundwork for possible anti-fouling strategies. Additionally, this will continue the synergistic collaboration between the University of Houston and PNNL scientists, which has already yielded two peer-reviewed publications.

Project Details

Project type
Limited Scope
Start Date
End Date


Principal Investigator

Shankar Chellam
University of Houston

Related Publications

1. Badireddy, A.R., S. Chellam, P. L. Gassman, M. H. Engelhard, A. S. Lea, and K. M. Rosso, (2010). Role of Extracellular Polymeric Substances in Bioflocculation of Activated Sludge Microorganisms under Glucose-controlled Conditions. Water Research, In Press (doi:10.1016/j.watres.2010.06.024).
Appala Raju Badireddy (2008). Interactions of Bacteria and Viruses with Membranes and Nanoparticles: Characterization of Extracellular Polymeric Substances and Photoinactivation of Bacteriophages by Fullerol Nanoparticles. Doctoral Dissertation, Department of Civil and Environmental Engineering, University of Houston, Houston, TX.