Abstract
This study represents the first characterization of sand microbiota in migrating barchan sand dunes. Bacterial communities were studied through direct counts and cultivation, as well as 16S rRNA gene and metagenomic sequence analysis to gain an understanding of microbial abundance, diversity, and potential metabolic capabilities. Direct on-grain cell counts gave an average of 5.3 ± 0.4 x 105 cells g-1 of sand. Cultured isolates (N = 64) selected for 16S rRNA gene sequencing belonged to the phyla Actinobacteria (58%), Firmicutes (27%) and Proteobacteria (15%). Deep-sequencing of 16S rRNA gene amplicons from 18 dunes demonstrated a high relative abundance of Proteobacteria, particularly enteric bacteria, and a dune-specific-pattern of bacterial community composition that correlated with dune size. Shotgun metagenome sequences of two representative dunes were analyzed and found to have similar relative bacterial abundance, though the relative abundances of eukaryotic, viral and enterobacterial sequences were greater in sand from the dune closer to a camel-pen. Functional analysis revealed patterns similar to those observed in desert soils; however, the increased relative abundance of genes encoding sporulation and dormancy are consistent with the dune microbiome being well-adapted to the exceptionally hyper-arid Qatari desert.
Highlights
Ten percent of the land mass between 30°S and 30°N is covered by mobile dunes [1]
Our questions were primarily: 1) What is the bacterial density within a barchan? 2) Does the microbial community change with depth? 3) Are there differences in community composition based on location along the dune? and 4) What factors influence community structure? Bacterial communities were studied through direct counts and cultivation, as well as by deep 16S rRNA gene amplicon and metagenomic sequence analyses in order to address these questions
Very little is known about the microbiology of Barchan dunes [29], though stationary dunes [13, 23,24,25,26,27,28], and desert soils have been previously studied by others [12, 15,16,17,18,19,20,21,22, 25]
Summary
Ten percent of the land mass between 30°S and 30°N is covered by mobile dunes [1]. Barchans are the simplest of mobile dunes. They form in desert areas where winds come predominantly from one direction. Barchan structure consists of a downwind slip face bordered by downwindfacing horns, separated from the gentler sloping windward dune face by a sharp crest [2,3,4], PLOS ONE | DOI:10.1371/journal.pone.0161836. Microbiology of Qatari Barchan Sand Dunes data collection and analysis, decision to publish, or preparation of the manuscript Barchan structure consists of a downwind slip face bordered by downwindfacing horns, separated from the gentler sloping windward dune face by a sharp crest [2,3,4], PLOS ONE | DOI:10.1371/journal.pone.0161836 September 21, 2016
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