Project description:Biological soil crusts (BSCs) are cyanobacteria-dominated microbial communities that cover extensive portions of the world’s arid and semi-arid deserts. The infrequent periods of hydration are often too short to allow for dormancy strategies based on sporulation; consequently, survival is based on the unique capabilities of vegetative cells to resuscitate from and re-enter a stress resistant dormant state, one of which is migration within the crust layers in response to hydration. In this study, we sought to characterize the events that govern the emergence of the dominant cyanobacterium from dormancy, its subsequent growth, and the events triggered by re-desiccation and a transition back to dormant state. We performed a 48 hour laboratory wetting experiment of a desert BSC and tracked the response of Microcoleus vaginatus using a whole genome transcriptional time-course including night/day periods. This allowed the identification of genes with a diel expression pattern, genes involved uniquely in the signaling after hydration and those that contribute primarily to desiccation preparation.
Project description:Desert microbial communities live in a pulsed ecosystem shaped by isolated and rare precipitation events. The Namib desert is one of the oldest continuously hyperarid ecosystems on Earth. In this study, surface microbial communities of open soils (without sheltering features like rocks, vegetation or biological soil crusts) are analysed. We designed an artificial rainfall experiment where a 7x7 (3.5 x 3.5 m) plot remained dry while an adjacent one received a 30 mm simulated rain. Samples were taken randomly in parallel from both plots at 10 min, 1 h, 3 h, 7 h, 24 h and 7 days after the watering moment. Duplicate libraries were generated from total (rRNA depleted) RNA and sequenced 2x150 bp in an Illumina Hiseq 4000 instrument.
