A meta-analysis of the publicly available bacterial and archaeal sequence diversity in saline soils

An integrated view of bacterial and archaeal diversity in saline soil habitats is essential for understanding the biological and ecological processes and exploiting potential of microbial resources from such environments. This study examined the collective bacterial and archaeal diversity in saline soils using a meta-analysis approach. All available 16S rDNA sequences recovered from saline soils were retrieved from publicly available databases and subjected to phylogenetic and statistical analyses. A total of 9,043 bacterial and 1,039 archaeal sequences, each longer than 250 bp, were examined. The bacterial sequences were assigned into 5,784 operational taxonomic units (OTUs, based on ≥97 % sequence identity), representing 24 known bacterial phyla, with Proteobacteria (44.9 %), Actinobacteria (12.3 %), Firmicutes (10.4 %), Acidobacteria (9.0 %), Bacteroidetes (6.8 %), and Chloroflexi (5.9 %) being predominant. Lysobacter (12.8 %) was the dominant bacterial genus in saline soils, followed by Sphingomonas (4.5 %), Halomonas (2.5 %), and Gemmatimonas (2.5 %). Archaeal sequences were assigned to 602 OTUs, primarily from the phyla Euryarchaeota (88.7 %) and Crenarchaeota (11.3 %). Halorubrum and Thermofilum were the dominant archaeal genera in saline soils. Rarefaction analysis indicated that less than 25 % of bacterial diversity, and approximately 50 % of archaeal diversity, in saline soil habitats has been sampled. This analysis of the global bacterial and archaeal diversity in saline soil habitats can guide future studies to further examine the microbial diversity of saline soils.