title: Ice Cores- A265
design: Bacterial communities become entrapped in ice as glaciers form providing a phylogenetic history of bacterial evolution. Photosynthetic bacteria such as Prochlorococcus in glacial ice have been detected by other means. This study compared glacial ice samples from two different depths at two different sites (Antarctica and Greenland) to provide genetic evidence for Prochlorococcus cells and to assess evolutionary changes in the 16S rRNA gene.