Abstract
Arid environments are defined by the lack of water availability, which is directly related to the mean annual precipitation (MAP), and high values of solar irradiation, which impacts the community composition of animals, plants, and the microbial structure of the soil. Recent advances in NGS technologies have expanded our ability to characterize microbiomes, allowing environmental microbiologists to explore the complete microbial structure. Intending to identify and describe the state-of-the-art of bacterial communities in arid soils at a global scale, and to address the effect that some environmental features may have on them, we performed a systematic review based on the PRISMA guideline. Using a combination of keywords, we identified a collection of 66 studies, including 327 sampled sites, reporting the arid soil bacterial community composition by 16S rDNA gene high-throughput sequencing. To identify factors that can modulate bacterial communities, we extracted the geographical, environmental, and physicochemical data. The results indicate that even though each sampled site was catalogued as arid, they show wide variability in altitude, mean annual temperature (MAT), soil pH and electric conductivity, within and between arid environments. We show that arid soils display a higher abundance of Actinobacteria and lower abundance of Proteobacteria, Cyanobacteria, and Planctomycetes, compared with non-arid soil microbiomes, revealing that microbial structure seems to be strongly modulated by MAP and MAT and not by pH in arid soils. We observed that environmental and physicochemical features were scarcely described among studies, hence, we propose a reporting guideline for further analysis, which will allow deepening the knowledge of the relationship between the microbiome and abiotic factors in arid soil. Finally, to understand the academic collaborations landscape, we developed an analysis of the author’s network, corroborating a low degree of connectivity and collaborations in this research topic. Considering that it is crucial to understand how microbial processes develop and change in arid soils, our analysis emphasizes the need to increase collaborations between research groups worldwide.
Highlights
About 40% of the world’s total land surface is classified as dryland soils according to the United Nations Committee to Combat Desertification (UNCCD)
These results indicate a high sensibility and low precision, which is expected since systematic reviews with high sensitivity strategies incline towards low precision, which is reflected in the high Number Needed to read (NNR) (22.2)
We can indicate that arid soils display a higher abundance of Actinobacteria and lower abundance of Proteobacteria, Cyanobacteria, and Planctomycetes, comparatively
Summary
About 40% of the world’s total land surface is classified as dryland soils according to the United Nations Committee to Combat Desertification (UNCCD). A meta-analysis of soil microbial communities shows that biogeography of microorganisms is driven by variables that are different to those of macroorganisms [12], and microbial communities are structurally dependant on local factors rather than large scale factors like geographical isolation [35]; Skujinš [37, 42]. Much is known about matters related to soil bacterial communities, we do not know the magnitude of the body of knowledge, nor do we fully understand the ecology of these communities in dryland ecosystems [25, 34]. Unveiling the patterns of bacterial communities from arid soils is essential for improving Earth system models [46], which are relevant for projecting the effects of phenomena as desertification [41]; Yhao Yongping et al [47]. Next-generation sequencing (NGS) description of soil communities has grown broadly, and initiatives like the Earth Microbiome Project [42] have arisen to increase our global-scale understanding of environmental microbiomes. Many independent researchers have sought to describe the arid soil bacterial communities studying individual arid environments [19, 26] and some have compared a couple of them [16, 27], but none have managed to compare arid environments globally
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
