Let my microbes go! The Red Sea and stress tolerance strategies of Prochlorococcus, cyanophage, and SAR11


***Monday, July 30, 2012
Redfield Auditorium - 12:00 Noon
Dr. Luke Thompson
Postdoctoral Fellow

Typical of the oligotrophic ocean, the epipelagic zone of the Red Sea is dominated numerically by Prochlorococcus, cyanophage, and SAR11.  However, little is known about what controls microbial growth in different environments, including the high-light, high-salinity Red Sea.  Comparative metagenomics can reveal adaptive responses linked to ecosystem-specific selective pressures.  We quantified the relative abundance of genetic functions among four marine microbiomes: Red Sea (RS), Mediterranean Sea (MED), Sargasso Sea (BATS), and North Pacific (HOT). Among Prochlorococcus populations, DNA repair and high light-related genes were enriched in RS and HOT, suggesting that the high irradiance of these seas creates UV-induced damage and high-light stress.  Among SAR11, genes for one-carbon metabolism and degradation of osmolytes were enriched in RS and MED, consistent with higher osmolyte concentrations in these high-salinity waters.  Diverse habitats thus impose different selective pressures on ubiquitous marine microbes, and geographically disparate yet physically similar seas exhibit similar genomic adaptations.