Mutator phenotypes: distribution, population dynamics, and impact on bacterial adaptation and evolution

The goals of the project are to clarify the environmental distribution and importance of bacterial mutator strains and to identify the mechanisms underlying the hyper-recombinogenic phenotype. Knowledge of the distribution, dynamics and selection of mutat or phenotypes is crucial for assessing the barriers to horizontal transfer of transgenes (from genetically modified organisms or other genes such as those conferring antibiotic resistance or enhanced pathogenicity to bacteria. Our hypotheses are 1) that m utator bacteria increase recombination rates in natural populations of bacteria and 2) that mutator strains of bacteria provide a major entryway for foreign DNA into bacterial populations. Selected strains collections will be a ssayed for the prevalence o f mutator phenotypes. Complementation and random mutagenesis techniques will be applied to identify genes involved in establishing mutator phenotypes. The molecular basis of identified mutators will be characterized further wit h respect to their ability to incorporate species-foreign DNA. Advancing the insight to the environmental dynamics of mutators will greatly benefit the understanding of how antibiotic resistance and virulence arise among environmental bacterial pathogens such as those causing prob lems in agricultural practices. Moreo ver, the gene products affecting the stability and uptake of foreign DNA in bacteria will be identified, of particular importancein medical microbiology.