Faculty Funded Work

Characterization of Exopolymers associated with Biofilms Developed under varying Environmental Conditions

Dr. Jerry H. Kavouras, PhD, Biology Department
Dr. Jason Keleher, PhD, Chemistry Department


This interdisciplinary undergraduate research project will characterize and quantify exopolymers produced by single-species biofilms of Staphylococcus aureus and Escherichia coli developed under varying conditions.  Exopolymers are produced by bacteria in biofilms for firm, irreversible adhesion to a surface.  Exopolymers also are important in organizing the three dimensional architecture of biofilms.  Chemical and physical factors influence the development and architecture of biofilms on surfaces.  Biofilm development time, temperature, and surface chemistry will be the factors under study.  Biofilms will be developed over short (hours) and long (days) periods of time.  Biofilms will be developed at 37°C and 28°C to determine if temperature influences exopolymer production.  The optimal growth temperature for E. coli and S. aureus is typically listed as 37°C.  Biofilms will be developed on glass and polystyrene surfaces, which vary greatly in terms of surface chemistry.  Quantification of total protein and carbohydrates in the extracted exopolymers will be performed using the Bradford and phenol-sulfuric acid assays, respectively.  The exopolymers will be characterized in regards to their molecular structure, functional groups, molecular weight, and complexation efficiency using HPLC, IR, Dynamic Light Scattering, and Electrostatic Binding Site Titration, respectively.  The data will provide information on the manner in which the same microorganisms adhere firmly to surfaces in biofilms over time and under different environmental conditions.  The data will also allow comparison of the strategies employed by these microorganisms during biofilm formation.  The study of biofilms has increased steadily over the last two decades because they play a significant role in antibiotic resistance, protection from disinfectants, and are the natural state of bacteria in nature.  Research has demonstrated that macromolecules produced by bacteria within biofilms can be virulence factors, specifically in the initial colonization of surfaces.  Therefore, a better understanding of the factors in biofilm development can ultimately lead to improved control measures or treatments for infectious diseases