Originally published as Genetics Published Articles Ahead of Print on February 3, 2008.

Genetics, Vol. 178, 1615-1622, March 2008, Copyright © 2008
doi:10.1534/genetics.107.082164

Drop-Size Soda Lakes: Transient Microbial Habitats on a Salt-Secreting Desert Tree

Noga Qvit-Raz*, Edouard Jurkevitch{dagger} and Shimshon Belkin*,1

* Department of Plant and Environmental Sciences, Institute of Life Sciences and {dagger} Department of Plant Pathology and Microbiology, Faculty of Agricultural, Food, and Environmental Quality Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel

1 Corresponding author: Department of Plant and Environmental Sciences, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
E-mail: shimshon{at}vms.huji.ac.il

We describe a hitherto unrecognized bacterial community, inhabiting the leaf surfaces of the salt-excreting desert tree Tamarix. High temperatures, strong radiation, and very low humidity dictate a daytime existence in complete desiccation, but damp nights allow the microbial population to proliferate in a sugar-rich, alkaline, and hypersaline solution, before drying up again after sunrise. The exclusively bacterial population contains many undescribed species and genera, but nevertheless appears to be characterized by relatively limited species diversity. Sequences of 16S rRNA genes from either isolates or total community DNA place the identified members of the community in five bacterial groups (Actinobacteria, Bacteroidetes, Firmicutes, {alpha}-, and {gamma}-Proteobacteria); in each of these, they concentrate in a very narrow branch that in most cases harbors organisms isolated from unrelated halophilic environments.