Transitions in the Bacterial Diversity of Soil Communities along the Arid-Hyperarid Margin of the Atacama Desert, Chile

Arid and hyperarid regions currently occupy approximately 20% of the terrestrial surface, an area that is predicted to increase as global climate change drives the desertification of marginal semi-arid regions. Few studies have evaluated the potential loss of microbial biodiversity associated with increasing aridity and the impact that this loss may have on desertification processes. This study documents changes in soil bacterial diversity at the hyperarid-arid margin of the Atacama Desert, Chile. A comparison of hyperarid-arid transition zone (TZ) bacterial communities (2500-2900 m) to an arid, ecosystem (4514 m) using 454-pyrosequencing revealed a two- to four- fold greater diversity in the arid community than in the TZ sites. In addition, 86% of the arid-site OTUs were not found in any of the TZ soils. Both arid and TZ communities were dominated by Actinobacteria and Chloroflexi, however diversity within these phyla was site specific with one of the driest sites (2547 m) containing the greatest abundance of novel organisms.