Microbial comparative genomics provides insights into gene function, bacterial speciation and evolutionary relationships. In the August 14 Proceedings of the National Academy of Sciences, Murray et al. describe an approach to explore genome diversity and relatedness in the absence of complete sequence information (Proc Natl Acad Sci USA 2001, 98:9853-9858). They used sequence information from the Shewanella oneidensis strain MR-1 to construct DNA microarrays containing over 100 full-length open reading frames (ORFs). They then hybridized the arrays with genomic DNA from nine other Shewanella species to investigate differences. They observed a good correlation between hybridization values and the percentage sequence similarity for known genes. Hierarchical clustering revealed the relationships between bacterial profiles and indicated the phylogenetic distances. Most genes in operons had higher levels of relatedness, suggesting that such an approach could identify horizontally acquired genes. Microbial genomic hybridizations should provide insights into bacterial diversity and speciation, leading to a better understanding of the basis for genotypic and phenotypic differences.
Proceedings of the National Academy of Sciences