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Microbial community response to hydration-desiccation cycles in desert soil

View Article: PubMed Central - PubMed

ABSTRACT

Life in desert soil is marked by episodic pulses of water and nutrients followed by long periods of drought. While the desert flora and fauna flourish after rainfall the response of soil microorganisms remains unclear and understudied. We provide the first systematic study of the role of soil aqueous habitat dynamics in shaping microbial community composition and diversity. Detailed monitoring of natural microbial communities after a rainfall event revealed a remarkable decrease in diversity and a significant transition in community composition that were gradually restored to pre-rainfall values during soil desiccation. Modelling results suggest a critical role for the fragmented aqueous habitat in maintaining microbial diversity under dry soil conditions and diversity loss with wetting events that increase connectivity among habitats. This interdisciplinary study provides new insights into wetting and drying processes that promote and restore the unparalleled microbial diversity found in soil.

No MeSH data available.


(A) The dynamics of relative abundance of soil microbial classes during the field observations. Each time point is an average of three biological replicates. Time zero is an average of three samples taken from fully desiccated soil during the summer of 2012. (B) Non-metric Multidimensional Scaling based on the soil rRNA sequencing (MiSeq) dataset. The size of the symbol corresponds to the water content measured in the soil at the time of sampling.
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f1: (A) The dynamics of relative abundance of soil microbial classes during the field observations. Each time point is an average of three biological replicates. Time zero is an average of three samples taken from fully desiccated soil during the summer of 2012. (B) Non-metric Multidimensional Scaling based on the soil rRNA sequencing (MiSeq) dataset. The size of the symbol corresponds to the water content measured in the soil at the time of sampling.

Mentions: We applied qPCR analysis on extracted ribosomal RNA showing that the total abundance of microbial ribosomes was stable over the wetting-drying cycle. We quantified the abundance of microbial ribosomes throughout the wetting and desiccation period in all our soil samples (see Figure S2). No significant changes in the total ribosomal count was detected except in the first sample taken during severe desiccation, which showed an order of magnitude decrease in ribosomal count. While the total abundance remained stable, the relative abundance exhibited dynamic changes following the rainfall event (Fig. 1A). Observed is that several taxa became dominant for the first few days after the rainfall (Enterobacterales, Clostridiales, Lactobacillales and Bacteroidales). Subsequently, these dominant classes slowly declined in the ensuing soil desiccation. Some of these, specifically Clostridiales, Lactobacillales and Bacteroidales are known to include many anaerobic species30 implying that some niches in the saturated desert soil have become anaerobic. Importantly, the pre-rainfall community composition was recovered within six to seven days as the soil water content dropped below 10% (g/g).


Microbial community response to hydration-desiccation cycles in desert soil
(A) The dynamics of relative abundance of soil microbial classes during the field observations. Each time point is an average of three biological replicates. Time zero is an average of three samples taken from fully desiccated soil during the summer of 2012. (B) Non-metric Multidimensional Scaling based on the soil rRNA sequencing (MiSeq) dataset. The size of the symbol corresponds to the water content measured in the soil at the time of sampling.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382909&req=5

f1: (A) The dynamics of relative abundance of soil microbial classes during the field observations. Each time point is an average of three biological replicates. Time zero is an average of three samples taken from fully desiccated soil during the summer of 2012. (B) Non-metric Multidimensional Scaling based on the soil rRNA sequencing (MiSeq) dataset. The size of the symbol corresponds to the water content measured in the soil at the time of sampling.
Mentions: We applied qPCR analysis on extracted ribosomal RNA showing that the total abundance of microbial ribosomes was stable over the wetting-drying cycle. We quantified the abundance of microbial ribosomes throughout the wetting and desiccation period in all our soil samples (see Figure S2). No significant changes in the total ribosomal count was detected except in the first sample taken during severe desiccation, which showed an order of magnitude decrease in ribosomal count. While the total abundance remained stable, the relative abundance exhibited dynamic changes following the rainfall event (Fig. 1A). Observed is that several taxa became dominant for the first few days after the rainfall (Enterobacterales, Clostridiales, Lactobacillales and Bacteroidales). Subsequently, these dominant classes slowly declined in the ensuing soil desiccation. Some of these, specifically Clostridiales, Lactobacillales and Bacteroidales are known to include many anaerobic species30 implying that some niches in the saturated desert soil have become anaerobic. Importantly, the pre-rainfall community composition was recovered within six to seven days as the soil water content dropped below 10% (g/g).

View Article: PubMed Central - PubMed

ABSTRACT

Life in desert soil is marked by episodic pulses of water and nutrients followed by long periods of drought. While the desert flora and fauna flourish after rainfall the response of soil microorganisms remains unclear and understudied. We provide the first systematic study of the role of soil aqueous habitat dynamics in shaping microbial community composition and diversity. Detailed monitoring of natural microbial communities after a rainfall event revealed a remarkable decrease in diversity and a significant transition in community composition that were gradually restored to pre-rainfall values during soil desiccation. Modelling results suggest a critical role for the fragmented aqueous habitat in maintaining microbial diversity under dry soil conditions and diversity loss with wetting events that increase connectivity among habitats. This interdisciplinary study provides new insights into wetting and drying processes that promote and restore the unparalleled microbial diversity found in soil.

No MeSH data available.