Mineral and Bacterial Diversities of Desert Sand Grains from South-East Morocco

Abstract

International audienceMineralogy and microbiology of sand from Merzouga (Morocco) were simultaneously characterized, with the purpose of contributing to a better understanding of the geomicrobiology of deserts. In spite of very low measured bacterial biomass, bacterial diversity on each of the five defined mineralogical classes, was found high. An original grain by grain cultivation method enabled to obtain bacterial isolates with an unusually high recovery rate. The results of this study show that the genus Arthrobacter is well adapted to this environment with a preference for grains other than the dominant mineral quartz, and that the genera Chelatococcus and Saccharotrix are strongly attached to the grains

The influence of surface soil physicochemistry on the edaphic bacterial communities in contrasting terrain types of theCentralNamibDesert

“…In such open soil environments, the heterogeneous distribution of minerals can create spatial variability in microhabitats and in (bio)available chemical elements. This has been observed in a culture‐dependant study on dune sand grains from the Merzouga Desert (Morocco), where bacterial diversity was found related to different mineralogies (Gommeaux et al ., ). Carson et al .…”

“…In addition, micro‐organisms contribute to the weathering of rock formations in desert ecosystems (Chen et al ., ; Borin et al ., ; Kutovaya et al ., ) and microbial community structures are influenced by the substrate mineral composition (Gommeaux et al ., ; Pietrasiak et al ., ; Steven et al ., ). An analysis of the influence of soil parental material on the distribution of microbial soil crusts in the Mojave and Colorado Deserts (Pietrasiak et al ., ) demonstrated that the proximity to granite bedrock and its associated ‘grusy’ granite soils were key determinants in crust distribution, indicating the importance of geology in shaping desert microbial soil crusts.…”

Temperature and humidity within a mobile barchan sand dune, implications for microbial survival

“…Using the live stain technique of Gommeaux et al [], we confirmed that microbes were present on sand grains sampled below the upwind slope of the same dune (Figure ). There, we also found evidence of biological respiration by collecting gas samples at depths of 30, 60, and 90 cm in April 2012.…”

“…[5] Recently, Gommeaux et al [2010] and Heulin et al [2003Heulin et al [ , 2012 showed that BSCs and plant rhizospheres are not alone in harboring desert microbes. They found that stationary, nonvegetated desert sand dunes in southeast Morocco contained approximately a thousand culturable microbes for every gram of sand.…”

“…[6] In fact, as this article will show, microorganisms are found below the surface of crescent-shaped barchan dunes, even though the latter can turn over their entire sand mass much more rapidly than the dune studied by Gommeaux et al [2010]. This presence was unexpected, since microbial viability is ultimately tied to sufficient sand moisture and moderate heat, whereas harsh atmospheric conditions, solar radiation, aeolian erosion of the windward slope, redeposition of dry sands on the leeward avalanche face, and rare precipitation all conspire against favorable humidity and temperature.…”