A Global Meta-Analysis of Halophilic Microbial Communities

Abstract:

Despite the variety of astrobiological targets in our solar system, many worlds share one unifying quality: saltiness. From the evaporites of Mars to the ion-rich plumes of Enceladus, understanding the habitability of salty habitats and their ability to preserve biosignatures is undeniably important in the search for life. Astrobiologists use terrestrial analogs as a key tool to study halophiles and their potential elsewhere in the solar system (Mancinelli et al 2003). However, little is understood about community structure and protein homology among different types of hypersaline terrestrial environments. Meta-analysis enables researchers to understand patterns across disparate locations and studies. With the increasing availability of genomic data, more meta-analyses have been undertaken to characterize microbial communities globally, such as soil communities across biomes (Fierer et al 2009, 2017). Furthermore, shotgun metagenomes are an excellent tool for understanding functional potential and community structure of microbial communities (Ventosa et al 2015). Therefore, we decided to undertake a meta-analysis of halophilic metagenomes worldwide in order to understand whether genetic adaptation strategies and protein homology link these locations, or if each salty location is unique. We are in the process of analyzing dozens of publicly available metagenomic samples, located in the literature and the IMG/M database, by reprocessing raw reads and examining taxonomy and beta-diversity before diving into analysis of genes of interest, functional pathways, and protein homology. These samples span the spectrum from Atacama endolithic niches to salty brines in Australia and Antarctica, and we therefore expect their microbial communities to be highly diverse. However, it remains to be seen whether these communities will share similar or disparate origins for their salt-tolerance strategies. Furthermore, it not yet clear where these halophiles come from—are they ubiquitous or unique? Answering these questions will help guide our understanding of the selective pressures of extreme environments and inform the search for life on other planets.