Desiccation- and Saline-Tolerant Bacteria and Archaea in Kalahari Pan Sediments

Abstract

More than 41% of the Earth’s land area is covered by permanent or seasonally arid dryland ecosystems. Global development and human activity have led to an increase in aridity, resulting in ecosystem degradation and desertification around the world. The objective of the present work was to investigate and compare the microbial community structure and geochemical characteristics of two geographically distinct saline pan sediments in the Kalahari Desert of southern Africa. Our data suggest that these microbial communities have been shaped by geochemical drivers, including water content, salinity, and the supply of organic matter. Using Illumina 16S rRNA gene sequencing, this study provides new insights into the diversity of bacteria and archaea in semi-arid, saline, and low-carbon environments. Many of the observed taxa are halophilic and adapted to water-limiting conditions. The analysis reveals a high relative abundance of halophilic archaea (primarily Halobacteria), and the bacterial diversity is marked by an abundance of Gemmatimonadetes and spore-forming Firmicutes. In the deeper, anoxic layers, candidate division MSBL1, and acetogenic bacteria (Acetothermia) are abundant. Together, the taxonomic information and geochemical data suggest that acetogenesis could be a prevalent form of metabolism in the deep layers of a saline pan.

Distribution of Microbial Generalists and Habitat Specialists in Soils Along a Climate Gradient in the Chilean Coastal Cordillera

“…The selection of highly competitive and adaptive species is an important prerequisite in extreme deserts, as only the ttest microorganisms survive by evolving elaborate life strategies. Although we were unable to identify a strong ecological preference, despite the availability of a comprehensive dataset of environmental variables, our results underline the importance of salinity as already discussed in recent studies [25,71]. Besides typical colonizers of global deserts (e.g.…”

“…Saprolite samples were prepared as technical replicates. The ampli cation assay was carried out in a total reaction volume of 25 followed by a nal elongation step for 7 min at 72 °C. PCR products were afterwards puri ed using carboxyl-coated magnetic beads (SPRI beads, Agencourt® AMPure® XP-Kit, Beckman Coulter, Brea CA, USA) following the manufacturer's protocol.…”

“…In contrast, archaea have been shown to comprise especially members of Thaumarchaeota in various terrestrial habitats, especially dominating in deserts and tropical forests [1]. Based on correlative relationships, several edaphic parameters like salinity [25], temperature [26,27], rainfall amount [28], vegetation type, organic carbon, and nutrient content [22,[29][30][31] have been shown to signi cantly shape a microbial community. Besides the environmental impact mentioned above, communities can also be controlled on a local-scale by habitat size, ecosystem productivity [32], and trophic interactions [33].…”

Discrete Community Assemblages Within Hypersaline Paleolake Sediments of Pilot Valley, Utah

“…32 33 34 INTRODUCTION 61 Douglas & Yang, 2002). Because such basins tend to maintain closed groundwater systems that 84 allow for continual wetting of the playa sediments, they continue to support modern-day 85 microbial ecosystems (Hollister et al, 2010 ;Genderjahn et al, 2018 ;Sirisena et al, 2018 ;86 McGonigle et al, 2019). Surveys of microbial diversity in saline sediments indicate that they can 87 be among the most taxonomically diverse communities known (Ventosa et al, 2008).…”

“…Hypersaline paleolake basins have also been proposed as habitability analogs for similar 92 environments on Mars, giving them astrobiological significance (Lynch et al, 2015). To date, the 93 few studies that have evaluated microbial ecology in hypersaline sediments have done so within 94 single vertical cores (Sirisena et al, 2018 ;Genderjahn et al, 2018). But closed basin systems 95 exhibit horizonal as well as vertical geochemical and mineralogical gradients (Eugster & Jones, 96 1979), thus a study that examines microbial diversity in both dimensions is warranted.…”