PNNL

Abstract

Salinity is one of the strongest environmental drivers of microbial evolution and community composition. Here we aimed to determine the impact of high salt concentrations (from 25 to 332 ppt) on community structure along a salinity gradient of reclaimed saltern ponds outside of San Francisco, California. The microbial community compositions were determined by 16S rRNA gene sequencing and analyses. In addition, we sequenced total metagenomic DNA and reconstructed 44 high-quality genome bins of individual halotolerant and halophilic microbes, including many novel phylotypes, to determine the metabolic strategies for life in saline habitats. With an increasing in salt concentration we found a significant shift from osmolyte-utilizing “salt-out” microbes towards “salt-in” microbes that are adapted to high intracellular salt concentrations, such as haloarchaea and Salinibacter ruber. This shift was more pronounced in the water communities compared to sediments. We also identified a variety of genes encoding carbohydrate-active enzymes with a range of isoelectric points that have potential biotechnological applications, including deconstruction of biofuel feedstocks under high ionic conditions.