Phenotypic Comparison of Soil, Waterborne, and Plant Associated Bacteria

Caesar, Thecan

Abstract

As a model system to investigate the mechanisms of saprobic persistence of Pseudomonas spp. and Enteric bacteria (species closely associated with plant rhizospheres), investigations of the production of proteases, lipases, chitinases, cellulase, hemicelluloses and other hydrolytic enzymes by rhizosphere bacteria will be made. The hypothesis is that these traits are much more predominant among rhizosphere bacteria because they would be necessary to permit growth and survival in the rhizosphere where these compounds are the major forms of carbon available. Isolations will be made by serial dilution from soils, root surfaces, and root tissue. Automated bacterial identification systems, chiefly the BIOLOG and API systems, will be utilized to identify bacteria isolated from plant rhizospheres and from nonrhizosphere soil. Identification to species will be done and the taxonomic data will be used to determined the role of various species in the ecology of the rhizosphere. Manual tests will be conducted for important phenotypic tests that are not available through API or the BIOLOG systems. The project will provide and require the development of skills of sterile technique, reading of biochemical test reactions, data manipulation and computerized identification of bacteria and finally, the use and understanding of numerical taxonomic techniques and statistical analyses. Much of the same skills are required for clinical bacteriology and many of the same species likely to be studied in the proposed work are from the same groups of bacteria from which species of clinical and public health significance are derived, such as Pseudomonas spp. and members of the Enterobacteriaceae. Thus, the project would provide excellent practical skills relevant to clinical and public health bacteriology. Furthermore, an understanding of bacterial diversity and ecology as it is based on bacterial physiology could be gained. The project will allow the student to understand the characteristics of bacteria similar in many ways to clinical and public health-related bacterial without exposure to pathogens or the need for specialized conditions that working with the such bacteria would entail.