scholarly journals Successive DNA extractions improve characterization of soil microbial communities

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e2915 ◽  
Author(s):  
Mauricio R. Dimitrov ◽  
Annelies J. Veraart ◽  
Mattias de Hollander ◽  
Hauke Smidt ◽  
Johannes A. van Veen ◽  
...  

Currently, characterization of soil microbial communities relies heavily on the use of molecular approaches. Independently of the approach used, soil DNA extraction is a crucial step, and success of downstream procedures will depend on how well DNA extraction was performed. Often, studies describing and comparing soil microbial communities are based on a single DNA extraction, which may not lead to a representative recovery of DNA from all organisms present in the soil. The use of successive DNA extractions might improve soil microbial characterization, but the benefit of this approach has only been limitedly studied. To determine whether successive DNA extractions of the same soil sample would lead to different observations in terms of microbial abundance and community composition, we performed three successive extractions, with two widely used commercial kits, on a range of clay and sandy soils. Successive extractions increased DNA yield considerably (1–374%), as well as total bacterial and fungal abundances in most of the soil samples. Analysis of the 16S and 18S ribosomal RNA genes using 454-pyrosequencing, revealed that microbial community composition (taxonomic groups) observed in the successive DNA extractions were similar. However, successive DNA extractions did reveal several additional microbial groups. For some soil samples, shifts in microbial community composition were observed, mainly due to shifts in relative abundance of a number of microbial groups. Our results highlight that performing successive DNA extractions optimize DNA yield, and can lead to a better picture of overall community composition.

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1128C-1128
Author(s):  
Shengrui Yao ◽  
Ian A. Merwin ◽  
Janice E. Thies

Apple (Malu ×domestica) replant disease (ARD) is a soil-borne disease syndrome of complex etiology that occurs worldwide when establishing new orchards in old fruit-growing sites. Methyl bromide (MB) has been an effective soil fumigant to control ARD, but safer alternatives to MB are needed. We evaluated soil microbial communities, tree growth, and fruit yield for three pre-plant soil treatments (compost amendment, soil treatment with a broad-spectrum fumigant, and untreated controls), and five clonal rootstocks (M7, M26, CG6210, CG30, and G16), in an apple replant site at Ithaca, N.Y. Molecular fingerprinting (PCR-DGGE) techniques were used to study soil microbial community composition of root-zone soil of the different soil treatments and rootstocks. Tree caliper, shoot growth, and yield were measured annually from 2002–04. Among the five rootstocks we compared, trees on CG6210 had the most growth and yield, while trees on M26 had the least growth and yield. Soil treatments altered soil microbial communities during the year after pre-plant treatments, and each treatment was associated with distinct microbial groups in hierarchical cluster analyses. However, those differences among fungal and bacterial communities diminished during the second year after planting, and soil fungal communities equilibrated faster than bacterial communities. Pre-plant soil treatments altered bulk-soil microbial community composition, but those shifts in soil microbial communities had no obvious correlation with tree performance. Rootstock genotypes were the dominant factor in tree performance after 3 years of observations, and different rootstocks were associated with characteristic bacterial, pseudomonad, fungal, and oomycetes communities in root-zone soil.


2020 ◽  
Vol 96 (3) ◽  
Author(s):  
Johan De Gruyter ◽  
James T Weedon ◽  
Stéphane Bazot ◽  
Steven Dauwe ◽  
Pere-Roc Fernandez-Garberí ◽  
...  

ABSTRACT Although ongoing research has revealed some of the main drivers behind global spatial patterns of microbial communities, spatio-temporal dynamics of these communities still remain largely unexplored. Here, we investigate spatio-temporal variability of both bacterial and eukaryotic soil microbial communities at local and intercontinental scales. We compare how temporal variation in community composition scales with spatial variation in community composition, and explore the extent to which bacteria, protists, fungi and metazoa have similar patterns of temporal community dynamics. All soil microbial groups displayed a strong correlation between spatial distance and community dissimilarity, which was related to the ratio of organism to sample size. Temporal changes were variable, ranging from equal to local between-sample variation, to as large as that between communities several thousand kilometers apart. Moreover, significant correlations were found between bacterial and protist communities, as well as between protist and fungal communities, indicating that these microbial groups change in tandem, potentially driven by interactions between them. We conclude that temporal variation can be considerable in soil microbial communities, and that future studies need to consider temporal variation in order to reliably capture all drivers of soil microbiome changes.


2021 ◽  
Author(s):  
Carla Cruz Paredes ◽  
Daniel Tajmel ◽  
Johannes Rousk

<p>Temperature is one of the most important environmental factors controlling both microbial growth and respiration. Warmer temperatures accelerate the rate at which microorganisms respire. Therefore, it is expected that climate warming will induce losses of carbon to the atmosphere through soil microbial respiration, representing a positive feedback to climate warming. However, there are multiple gaps in our understanding on responses of microorganisms to warming. For instance, long-term experiments have shown that the increase in soil respiration found in warming experiments diminishes with time, recovering to ambient values. This suggests that soil C losses might not be as extensive as previously suggested. This can be due to substrate depletion or shifts in the microbial community composition that led to thermal adaptation. To test thermal adaptation of soil microbial communities to their climate, variation along latitudinal gradients is a useful context. Such geographical gradients have long-term and large temperature differences thus patterns in thermal adaptation should have had sufficient time for ecological and evolutionary processes to act, allowing us to test if soil microbial communities have adapted to thermal regimes.</p><p>We investigated a latitudinal gradient across Europe with 76 sites that spanned a gradient of decadal mean annual temperature (MAT) from -3.1 to 18.3°C. We investigated if respiration, bacterial and fungal growth responses were adapted to long-term temperature differences in this gradient. We did this by estimating the temperature dependences of bacterial growth, fungal growth and respiration. We determined the temperature sensitivity (Q<sub>10</sub>), the minimum temperature (T<sub>min</sub>) for growth and the optimum temperature (T<sub>opt</sub>) for growth. These metrics were then correlated to MAT. Additionally, we sequenced bacterial (16S) and fungal (ITS) amplicons from the different sites to also assess variance in community composition and structure. We hypothesized that microbes should be adapted to their historical temperature; microbial communities in warmer environments will be warm-shifted and vice versa.</p><p>We could effectively represent temperature relationships for bacterial growth, fungal growth, and respiration for all soils. As expected, temperature relationships correlated with the environmental temperature of the site, such that higher temperatures resulted in microbial communities with warm-adapted growth and respiration. This could be seen as a strong positive correlation between T<sub>min</sub> values and environmental temperatures which range from -14 to -5°C for bacteria, -11.5 to -4°C for fungi and -8 to -2°C for respiration. We found that MAT explains the microbial communities’ temperature dependencies for bacterial growth and respiration, but not for fungal growth. With 1°C rise in MAT, T<sub>min</sub> increased 0.17°C for bacterial growth, while T<sub>min</sub> for respiration increased by 0.11. Similarly, bacterial and fungal communities’ composition were correlated with MAT (r<sup>2</sup>=0.38; r<sup>2</sup>=0.62), and T<sub>min</sub> (r<sup>2</sup>=0.16; r<sup>2</sup>=0.21). These findings suggest that thermal adaptation occurs in processes such as bacterial growth and respiration, probably due to shifts in the microbial community composition. However, fungal growth seems to be less sensitive to changes in temperature, even though fungal communities’ composition was correlated with MAT.</p>


2019 ◽  
Vol 95 (11) ◽  
Author(s):  
Jianrong Huang ◽  
Jian Yang ◽  
Hongchen Jiang ◽  
Geng Wu ◽  
Zhanling Xie ◽  
...  

ABSTRACT Little is known about the onshore microbial contribution to the microbial communities in nearby lakes and its response to salinity. In this study, transplanting experiments were established by caging onshore soils with dialysis bags followed by in situ 50-day incubation in nearby lakes with different salinity on the Qinghai-Tibetan Plateau. At the end of the experiment, geochemical and microbial analyses were performed on the original soils, caged soils and lake waters and sediments at the incubation sites. The results showed that the salinity increased significantly (P < 0.05) in the caged soils and such salinity increases showed significant (P < 0.05) positive correlation with the salinity of the studied lakes. The microbial community composition and predicted functions in the caged soils were significantly (P < 0.05) changed in comparison with their corresponding original soils, and such variation could be mainly explained by the succession of members of the Proteobacteria, Bacteroidetes and Actinobacteria from the original soils to their corresponding caged soils. The onshore microbial contribution appeared to be limited (up to 11.2% for sediment and negligible for water, respectively) to nearby lake microbial communities. Nevertheless, the survival of onshore soil microbial communities was mainly limited by the salinity of the receiving lakes.


2021 ◽  
Author(s):  
Cong Jiang ◽  
Wei Shui ◽  
Su-Feng Zhu ◽  
Jie Feng

Abstract Background: Karst tiankeng is a large-scale negative surface terrain, and slope aspect affect the soil conditions, vegetation and microbial flora in the tiankeng. However, the influence of the slope aspect on the soil microbial community in tiankeng has not been elucidated. Methods: In this study, metagenomic sequencing technology was used to analyzed the soil microbial communities and metabolic function on the shady and sunny slopes of karst tiankeng. Results: The Shannon-Wiener diversity of microbial communities on shady slopes was significantly higher than that on shady slopes. Shady and sunny slopes have similar microbial community composition, but there are differences in abundance. The linear discriminate analysis (LDA) results showed that biomarkers mainly belongs to Actinobacteria, Chloroflexi and Proteobacteria. Functional pathways and CAZy (Carbohydrate-Active Enzymes) genes also had a remarkable response to slope aspect change. LEfSe results indicated several biomarker pathways in sunny slope involved in human disease. Moreover, the abundance of CAZy genes was higher in shady slope and had stronger ability in decomposing litter. The microbial communities were mainly correlation with the vegetation characteristics (species richness and coverage) and soil properties (SOM and pH). Conclusions: These results indicate slope aspect has a pronounced influence on microbial community composition, structure and function at karst tiankeng. In the future, the conservation of karst tiankeng biodiversity should pay more attention to topographical factors.


2015 ◽  
Vol 12 (13) ◽  
pp. 10359-10387 ◽  
Author(s):  
W. Y. Dong ◽  
X. Y. Zhang ◽  
X. Y. Liu ◽  
X. L. Fu ◽  
F. S. Chen ◽  
...  

Abstract. Nitrogen (N) and phosphorus (P) additions to forest ecosystems are known to influence various above-ground properties, such as plant productivity and composition, and below-ground properties, such as soil nutrient cycling. However, our understanding of how soil microbial communities and their functions respond to nutrient additions in subtropical plantations is still not complete. In this study, we added N and P to Chinese fir plantations in subtropical China to examine how nutrient additions influenced soil microbial community composition and enzyme activities. The results showed that most soil microbial properties were responsive to N and/or P additions, but responses often varied depending on the nutrient added and the quantity added. For instance, there were more than 30 % greater increases in the activities of β-Glucosidase (βG) and N-acetyl-β-D-glucosaminidase (NAG) in the treatments that received nutrient additions compared to the control plot, whereas acid phosphatase (aP) activity was always higher (57 and 71 %, respectively) in the P treatment. N and P additions greatly enhanced the PLFA abundanceespecially in the N2P treatment, the bacterial PLFAs (bacPLFAs), fungal PLFAs (funPLFAs) and actinomycic PLFAs (actPLFAs) were about 2.5, 3 and 4 times higher, respectively, than in the CK. Soil enzyme activities were noticeably higher in November than in July, mainly due to seasonal differences in soil moisture content (SMC). βG or NAG activities were significantly and positively correlated with microbial PLFAs. There were also significant relationships between gram-positive (G+) bacteria and all three soil enzymes. These findings indicate that G+ bacteria is the most important microbial community in C, N, and P transformations in Chinese fir plantations, and that βG and NAG would be useful tools for assessing the biogeochemical transformation and metabolic activity of soil microbes. We recommend combined additions of N and P fertilizer to promote soil fertility and microbial activity in this kind of plantation.


2021 ◽  
Vol 12 ◽  
Author(s):  
Scott F. George ◽  
Noah Fierer ◽  
Joseph S. Levy ◽  
Byron Adams

Ice-free soils in the McMurdo Dry Valleys select for taxa able to cope with challenging environmental conditions, including extreme chemical water activity gradients, freeze-thaw cycling, desiccation, and solar radiation regimes. The low biotic complexity of Dry Valley soils makes them well suited to investigate environmental and spatial influences on bacterial community structure. Water tracks are annually wetted habitats in the cold-arid soils of Antarctica that form briefly each summer with moisture sourced from snow melt, ground ice thaw, and atmospheric deposition via deliquescence and vapor flow into brines. Compared to neighboring arid soils, water tracks are highly saline and relatively moist habitats. They represent a considerable area (∼5–10 km2) of the Dry Valley terrestrial ecosystem, an area that is expected to increase with ongoing climate change. The goal of this study was to determine how variation in the environmental conditions of water tracks influences the composition and diversity of microbial communities. We found significant differences in microbial community composition between on- and off-water track samples, and across two distinct locations. Of the tested environmental variables, soil salinity was the best predictor of community composition, with members of the Bacteroidetes phylum being relatively more abundant at higher salinities and the Actinobacteria phylum showing the opposite pattern. There was also a significant, inverse relationship between salinity and bacterial diversity. Our results suggest water track formation significantly alters dry soil microbial communities, likely influencing subsequent ecosystem functioning. We highlight how Dry Valley water tracks could be a useful model system for understanding the potential habitability of transiently wetted environments found on the surface of Mars.


2021 ◽  
Author(s):  
Dajana Radujković ◽  
Sara Vicca ◽  
Margaretha van Rooyen ◽  
Peter Wilfahrt ◽  
Leslie Brown ◽  
...  

Environmental circumstances shaping soil microbial communities have been studied extensively, but due to disparate study designs it has been difficult to resolve whether a globally consistent set of predictors exists, or context-dependency prevails. Here, we used a network of 18 grassland sites (11 sampled across regional plant productivity gradients) to examine i) if the same abiotic or biotic factors predict both large- and regional-scale patterns in bacterial and fungal community composition, and ii) if microbial community composition differs consistently with regional plant productivity (low vs high) across different sites. We found that there is high congruence between predictors of microbial community composition across spatial scales; bacteria were predominantly associated with soil properties and fungi with plant community composition. Moreover, there was a microbial community signal that clearly distinguished high and low productivity soils that was shared across worldwide distributed grasslands suggesting that microbial assemblages vary predictably depending on grassland productivity.


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