Studying bacterial genome dynamics using microarray-based comparative genomic hybridization.

Genome sequencing has revealed the remarkable amount of genetic diversity that can be encountered in bacterial genomes. In particular, the comparison of genome sequences from closely related strains has uncovered significant differences in gene content, hinting at the dynamic nature of bacterial genomes. The study of these genome dynamics is crucial to leveraging genomic information because the genome sequence of a single bacterial strain may not accurately represent the genome of the species. The dynamic nature of bacterial genome content has required us to apply the concepts of comparative genomics (CG) at the species level. Although direct genome sequence comparisons are an ideal method of performing CG, one current constraint is the limited availability of multiple genome sequences from a given bacterial species. DNA microarray-based comparative genomic hybridization (MCGH), which can be used to determine the presence or absence of thousands of genes in a single hybridization experiment, provides a powerful alternative for determining genome content and has been successfully used to investigate the genome dynamics of a wide number of bacterial species. Although MCGH-based studies have already provided a new vista on bacterial genome diversity, original methods for MCGH have been limited by the absence of novel gene sequences included in the microarray. New applications of the MCGH platform not only promise to accelerate the pace of novel gene discovery but will also help provide an integrated microarray-based approach to the study of bacterial CG.