The Role of Extracellular Polymeric Substances in Bacterial Fouling of Membranes
EMSL Project ID
26592
Abstract
Micro- and nano-porous membranes are currently employed for environmental separations to protect public health arising from a plethora of contaminants including microorganisms, natural and synthetic organic compounds, inorganic chemicals, as well as particulate matter. In spite of the large economic market and business interests related to membranes, every membrane installation is influenced by fouling.
Developing an improved understanding of factors controlling bacterial fouling of membranes and ultimately its control is the principal goal of the proposed research.
Objectives. We propose to examine the factors controlling biofilm formation on nanofiltration membranes using Brevundimonas diminuta as a model bacterium. Our focus will be on expression of extracellular polymeric substances (EPS), its detailed characterization, and finally its control using bismuth dimercaptopropanol (BisBAL). We will systematically and rigorously examine interactions between these EPS and membranes in the absence and presence of BisBAL.
Hypotheses. (1) bacterial expression of EPS exacerbates their adhesion to membrane surfaces; and (2) EPS secretion can be modified through interactions with lipophilic thiol chelates of bismuth such as BisBAL).
Approach. This is collaborative effort brings together expertise in membrane technologies (Shankar Chellam at the University of Houston), atomic force microscopy (Kevin Rosso at EMSL) and infra-red spectroscopy (Paul Gassman at EMSL). We will determine the characteristics of polysaccharides, proteins, and peptides present in free-EPS and bound-EPS using Fourier-transform infra-red spectroscopy. We will also focus on in situ analysis of membrane biofilms using nuclear magnetic resonance spectroscopy (NMR), atomic force microscopy (AFM) and environmental scanning electron microscopy (ESEM) The effort is organized into the following tasks: (1) preparation of BisBAL solutions at 2:1 molar ratio; (2) preparation of membrane samples with B. diminuta deposited under varying hydrodynamic conditions and BisBAL concentrations; (3) colorimetric, microscopic, and spectroscopic analysis of EPS extracted from the biofilm; and (4) develop a conceptual model for biological membrane fouling.
Intellectual merit and major outcomes. Understanding the interactions between synthetic membranes and bacteria is important to ensure that high quality water is made available even as the quality of existing source waters decrease. At the conclusion of this project, we will have an improved understanding of the physicochemical and microbiological factors that control bacterial adhesion and EPS expression. This will benefit membrane implementation and may contribute indirectly to the development of innovative fouling mitigation strategies.
Student training. Two environmental engineering doctoral students will gain interdisciplinary and collaborative experience working with EMSL scientists on advanced microscopic and spectroscopic measurements, environmental separations, and microbiology.
Project Details
Project type
Exploratory Research
Start Date
2007-11-01
End Date
2008-11-02
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
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.
Badireddy AR, BR Korpol, S Chellam, PL Gassman, MH Engelhard, AS Lea, and KM Rosso. 2008. "Spectroscopic Characterization of Extracellular Polymeric Substances from Escherichia coli and Serratia marcescens: Suppression using Sub-Inhibitory Concentrations of Bismuth Thiols." Biomacromolecules 9(11):3079-3089. doi:10.1021/bm800600p
Badireddy AR, BR Korpol, S Chellam, PL Gassman, MH Engelhard, AS Lea, and KM Rosso. 2008. "Spectroscopic Characterization of Extracellular Polymeric Substances from Escherichia coli and Serratia marcescens: Suppression using Sub-Inhibitory Concentrations of Bismuth Thiols." Biomacromolecules 9(11):3079-3089. doi:10.1021/bm800600p