One approach towards controlling bacterial biofilms is to develop "non-stick" surfaces to which the bacteria cannot adhere. We have been determining the effects of surface chemistry on bacterial attachment by constructing homogeneous substrata with known functional groups by using self-assembled monolayers. Kinetics of bacterial attachment to test surfaces has been determined in flow chambers using microscopy and image analysis. On another level, we have focused on the bacteria themselves and have been generating transposon mutants with altered adhesion properties, so that the specific macromolecules involved in adhesion can be identified and characterized. Alterations in adhesive properties of the bacteria are also being related to their transport through porous sediments, which has implications for the use of microorganisms for in situ bioremediation.
Most recently, we have been developing molecular tools for analyzing microbial communities. The compositions of biofilms are poorly understood, since bacteria from the natural environment are frequently impossible to culture in the laboratory. By extracting and analyzing low molecular weight RNA (5S rRNA and tRNA) on polyacrylamide gels, characteristic profiles of communities are produced, and these can be further analyzed by computer pattern-recognition techniques This approach is being used to evaluate total community composition, to compare communities from different habitats or seasons, and to detect community changes induced by environmental factors.
Bidle, K. and M. Fletcher (1995). Comparisons of free-living and particle-associated bacterial communities in the Chesapeake Bay using stable low-molecular-weight RNA analysis. Appl. Environ. Microbiol. 61:944-952.
Wiencek, K.R. and M. Fletcher. (1995). Bacterial adhesion to hydroxyl- and methyl-terminated alkanethiol self-assembled monolayers. J. Bacteriol. 177:1959-1966.
Williams, V. and M. Fletcher. (1996). Adhesion and transport through porous media of Pseudomonas fluorescens is affected by lipopolysaccharide composition. Appl. Environ. Microbiol. 62: 100-104.
Fletcher, M. (ed.) (1996). The Molecular and Ecological Diversity of Bacterial Adhesion to Surfaces. New York: John Wiley. 10/9/96