Bacterial physiology in biofilms

We have studied a microbial community capable of degrading toluene and derivative compounds through the use of quantitative in situ rRNA hybridization, gene expression using fluorescent reporters and gene transfer.
The community is composed of 7 members of which 3 organisms are capable of degrading toluene to carbon dioxide and water. The community is grown as continuous surface cultures in flow chambers with benzyl alcohol as the only carbon source. Population structure (relative proportions of the 7 species as well as their positions in three dimensions) are determined using in situ rRNA hybridization and confocal microscopy. Physiological activity is determined through quantitative rRNA hybridizations in single cells, from which growth rates are estimated. Specific gene expression is monitored through the use of green fluorescent protein as a reporter (allows single cell detection). Transfer of conjugative plasmids is followed as zygotic induction of GFP in transconjugant cells in the community.
All methods used have been developed for applications in single cells for inspection in the fluorescence or confocal microscope.
The goal is to build up an understanding of the way bacteria organise their activities in complex communities, and eventually to understand the coordinative aspects of this type of 'social life'. This first phase of the project was terminated at the end of 1999, due to the run-out of the Biotech framework grant. A new phase of this project financed through the anchoring of the Biotech grant will be initiated in 2000.