Adaptability of Biofilm Exopolymeric Substances to Hydrophobicity and Hydrophilicity

EPA Grant Number: U915832
Title: Adaptability of Biofilm Exopolymeric Substances to Hydrophobicity and Hydrophilicity
Investigators: Steinberger, Rachel E.
Institution: University of California - Santa Barbara
EPA Project Officer: Michaud, Jayne
Project Period: August 1, 2000 through August 1, 2003
Project Amount: $77,989
RFA: STAR Graduate Fellowships (2000) RFA Text |  Recipients Lists
Research Category: Fellowship - Microbiology , Academic Fellowships , Biology/Life Sciences


The objective of this research project is to understand how hydrophobic substances and surfaces stimulate changes in the exopolymeric substances surrounding bacteria and the consequences of those changes on rates of bioremediation.


The paradigm behind this work is one of comparative differences. Using Pseudomonas aeruginosa as a model organism, exopolymers (EPS) collected from parallel cultures grown under different conditions are characterized by both chemical composition and functional properties. Cultures grow in both saturated and unsaturated conditions, using no substrata, hydrophobic (polystyrene) substrata, and hydrophilic (sand) substrata. The bacteria also are grown on a variety of carbon sources with varying hydrophobicity, including glucose, decane, and hexadecane. Using measured values from these experiments as parameters, a simple numerical model will be constructed describing the transfer of pollutants to the bacteria on a microscale. The model's predictions will be compared with long-term small-scale laboratory bioremediation experiments.

Expected Results:

In most natural environments, bacteria live predominantly in communities encased by bacterial EPS. The EPS forms a mass transfer barrier creating a microenvironment for the bacteria distinctly different from the macroenvironment. By changing the chemical compositions of this barrier, the bacteria should be able to mediate what comes into their environment. Because bioremediation of most pollutants is mass transfer-limited, an understanding of the relation between changes in EPS chemical properties and the uptake of organic pollutants will improve our ability to accurately predict rates of bioremediation.

Supplemental Keywords:

soil, absorption, bioavailability, toxics, organics, NAPL, bacteria, bioremediation, biology, biofilms, EPS, hydrophobicity, Pseudomonas aeruginosa., Scientific Discipline, Waste, Ecosystem Protection/Environmental Exposure & Risk, Bioavailability, Remediation, Chemistry, Fate & Transport, Microbiology, Environmental Microbiology, Bioremediation, model, organic pollutants, exopolymers (EPS), NAPL, microenvironment, modeling, soils, mass transfer, model organism, organics, Pseudomonas aeruginosa, models, absorption, numerical modeling, biofilm model, mass transfer limitations, exoplymeric substances, organic contaminants

Progress and Final Reports:

  • 2001
  • 2002
  • Final