ABSTRACT
Background Evolution of a microbe is often driven by its environment or life-style. Microorganisms adapted to some specialized environmental conditions have been reported to display conspicuous genome and/or proteome features [1-8]. Species of widely varying taxonomic origins, but thriving in same/similar environmental conditions such as high temperature or high salinity, may converge to similar genome and/or proteome composition. In contrast, closely related bacterial species inhabiting distinct ecological niches may display substantial genomic diversity [1-3,6,8-11]. Unveiling the plausible causes/consequences, at the genome and proteome levels, of such niche-dependent evolution of the microbial world poses a major challenge to the present-day life-scientists. e marine cyanobacterium Prochlorococcus marinus [12], having multiple ecotypes exhibiting distinct nichespecic phenotypic as well as genotypic characteristics, oers a useful system to address this issue.
