Erik Zinser, Ph.D.
The University of Tennessee, Knoxville
Temperature and Reactive Oxygen Species as Ecological Determinants for Prochlorococcus
Wednesday - April 8, 2009
Pacific Forum – 3:00 p.m.
The first twenty years of research on the marine cyanobacterium Prochlorococcus has taught us much about the global distribution and the genetic and physiological diversity within this numerically-dominant lineage. One of the key challenges for the Prochlorococcus research community in the 21st century is to identify the physiological traits that determine the abundances and activities of the different lineages in nature. Our laboratory has focused on two environmental factors that strongly influence Prochlorococcus growth and survival: temperature and oxidative stress. Lineages of Prochlorococcus are broadly distributed into high-light- and low-light-adapted ecotypes, and optimization for growth at different temperatures further partitions the niche between the two high-light adapted ecotypes. Our analysis of Prochlorococcus in the Pacific Ocean, and in particular the Western Pacific Warm Pool - with temperatures exceeding 30°C – confirms and extends these observations. Laboratory and field studies have further indicated that Prochlorococcus cells are especially sensitive to reactive oxygen species, and we have discovered that their heterotrophic bacterial neighbors play a critical role in protecting them from these harmful agents.