9520272 Hines Molecular techniques that use 16S rRNA as phylogenetic descriptors offer potential for delineating the microscale structure and activity of rhizosphere bacterial communities in a manner that was not previously possible. Studies are currently underway which are investigating the population composition of sulfate-reducing bacteria in a salt marsh rhizosphere by: 1) probing bulk RNA; 2) amplifying and sequencing of rRNA genes for determining diversity, and 3) enumerating, isolating and characterizing sulfate-reducing bacteria. The research in this dissertation proposal will complement this work by investigating bacteria on plant roots at the cellular level using in situ hybridization technology which has only recently become advanced enough to visualize bacteria on roots using fluorescent probes and confocal laser microscopy. This goal will be achieved by conducting preliminary investigations, and then visiting the laboratory of Dr. R. Amman in Germany who has agreed to instruct the student investigator in the state of the art of using laser microscopy and in site hybridization techniques with fluorescence detection. The work will be completed using the laser microscope at the Gulf Breeze EPA Laboratory in collaboration with Dr. R. Devereux. Development and application of in situ techniques will enable the identification and visualization of individual bacteria in their native microhabitat, will elucidate the micro-ecology of these bacteria in relation to their spatial arrangements with other bacteria, and will demonstrate the interaction of bacteria with various parts of the root. The results will not only portray complex biogeochemical interactions between microbiota and plants, but will provide a manner in which to monitor exogenous bacteria artificially introduced into the rhizosphere.
