Igor Jouline, UT-Oak Ridge National Laboratory joint faculty professor of microbiology and researcher at ORNL's Joint Institute for Computational Sciences, performed a genome sequence analysis of the soil bacteria Azospirillum, a species' whose forebearers made the sea-to-land move. The analysis indicates the shift may have occurred only 400 million years ago, rather than approximately two billion years earlier, as originally thought.
Published in the journal PLoS Genetics, Jouline calculated the timing of the sea-land transition through studies of genome sequences of two species of Azospirillum, a terrestrial genus with almost exclusively aquatic relatives.
Jouline conducted his research with Kristin Wuichet and Leonid Sukharnikov of the Department of Microbiology, Gladys Alexandre of Department of Biochemistry, Cellular, and Molecular Biology, and Kirill Borziak, a graduate student in the ORNL-UT Genome Science and Technology program.
"In the absence of fossil records for bacteria, it is hard to estimate when and how bacteria transitioned from sea to land," said Jouline. "Using genome sequencing and analysis of bacteria of the genus Azospirillum, which colonizes roots of important cereals and grasses, we show that these organisms transitioned from aquatic environments to land approximately at the same time that plants appeared on land -- 400 million years ago."
