Abstract
The living stromatolites of Shark Bay, Western Australia, represent analogues of one of the oldest life on Earth located in a hyersaline environment. This is an ideal biological system for studying survival strategies of complex microbial communities in an environmental condition suggested to be similar to that of early Earth. The aim of this study was to study osmoprotective mechanisms of cyanobacteria and archaea isolated previously [1] from the stromatolite. The presence of several osmolytes/compatible solutes in the microbial communities were detected by nuclear magnetic resonance spectroscopy (NMR). DNA molecular methods such as Panhandle PCR was also employed to identify candidate genes for the uptake of osmoprotectants. We identified a glycine betaine uptake system, OpuD gene homologues, as well as several genes encoding regulated salinity proteins in the halophilic archaea. This study provides an excellent platform for the identification of potentially novel osmolytes/compatible solutes that might have been produced by these microorganisms. Exploitation of the osmolyte accumulation mechanisms discovered could also lead to the genetic enhancement of drought and salinity tolerance in crop plants.
