scholarly journals Characteristics of the Soil Microbial Communities in Different Slope Positions along an Inverted Stone Slope in a Degraded Karst Tiankeng

Biology ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 474
Author(s):  
Cong Jiang ◽  
Jie Feng ◽  
Su-Feng Zhu ◽  
Wei Shui

The underground forests developed on inverted stone slopes in degraded karst tiankengs are important areas for biodiversity conservation, but the microbial community profiles have not been sufficiently characterized. Thus, we investigated the soil microbial communities at four sites (at the bottom of the slope (BS), in the middle of the slope (MS), in the upper part of the slope (US) and outside the tiankeng (OT)) in the Shenxiantang tiankeng. The dominant phyla in the inverted stone slope were Proteobacteria, Actinobacteria, and Acidobacteria, and the relative abundance were different in different slope positions. The Shannon–Wiener diversity index of the microbial community was significantly greater for the US site than for the MS or BS sites. The metabolism functional pathways (including C/N cycle) were more abundant at the BS site. Total nitrogen and pH were the dominant factors in determining the distribution of the microbial community along an inverted stone slope. These results suggest that topographic heterogeneity can influence the variations in the soil microbial structure, diversity, and function in degraded karst tiankengs and emphasized the ecological value of inverted stone slopes within karst tiankengs.

Forests ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 532 ◽  
Author(s):  
Chaoqun Wang ◽  
Lin Xue ◽  
Yuhong Dong ◽  
Yihui Wei ◽  
Ruzhen Jiao

The structure and function of forest ecosystems are directly or indirectly affected by their stand density. However, what effect the density of Chinese fir plantations has on the functional diversity of the soil microbial community remains unclear. The microbial metabolic functional diversity of soils sampled at the topsoil (0–20 cm) of 35-year-old Chinese fir plantations of five initial densities (D1: 1667 stems∙hm−2, D2: 3333 stems∙hm−2, D3: 5000 stems∙hm−2, D4: 6667 stems∙hm−2, and D5: 10,000 stems∙hm−2) was studied by using Biolog ECO technology. The results showed that the soil pH, oxidizable organic carbon (SOOC), available N (AN), available P (AP), and available K (AK) contents all showed a gradual increase from D1 to D4 and a decrease from D4 to D5, while the number of culturable bacteria and total microorganisms, the average well color development (AWCD) values for the single carbon substrate and six types of carbon sources used by the microbial community, as well as the Shannon-Wiener diversity index (H’), Pielou evenness index (J), and McIntosh Diversity Index (U), were the opposite, suggesting that low-densities favored C and N mineralization and the nutrient cycle. The density of Chinese fir plantations had a significant effect on the use of carbohydrates, amino acids, carboxylic acids, and phenolic acids by the soil microbial community, but it had no significant effect on the use of polymers (p < 0.05). Principal component analysis (PCA) revealed that carbohydrates, polymers, and phenolic acids were sensitive carbon sources that caused differences in the metabolic functions of soil microbial communities in Chinese fir plantations. Redundancy analysis (RDA) showed that physicochemical factors have a significant influence on the metabolic function of soil microbial communities (RDA1 and RDA2 explained >85% variance). The changes in density affected the soil physicochemical properties, the composition, and the metabolic functional diversity of microbial communities in Chinese fir plantations, which is certainly useful for the stand density regulation of Chinese fir plantations.


Agronomy ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 173
Author(s):  
Huiling Guan ◽  
Jiangwen Fan ◽  
Haiyan Zhang ◽  
Warwick Harris

Soil erosion is prevalent in karst areas, but few studies have compared the differences in the drivers for soil microbial communities among karst ecosystems with different soil depths, and most studies have focused on the local scale. To fill this research gap, we investigated the upper 20 cm soil layers of 10 shallow–soil depth (shallow–SDC, total soil depth less than 100 cm) and 11 deep–soil depth communities (deep–SDC, total soil depth more than 100 cm), covering a broad range of vegetation types, soils, and climates. The microbial community characteristics of both the shallow–SDC and deep–SDC soils were tested by phospholipid fatty acid (PLFAs) analysis, and the key drivers of the microbial communities were illustrated by forward selection and variance partitioning analysis. Our findings demonstrated that more abundant soil nutrients supported higher fungal PLFA in shallow–SDC than in deep–SDC (p < 0.05). Furthermore, stronger correlation between the microbial community and the plant–soil system was found in shallow–SDC: the pure plant effect explained the 43.2% of variance in microbial biomass and 57.8% of the variance in the ratio of Gram–positive bacteria to Gram–negative bacteria (G+/G−), and the ratio of fungi to total bacteria (F/B); the pure soil effect accounted for 68.6% variance in the microbial diversity. The ratio of microbial PLFA cyclopropyl to precursors (Cy/Pr) and the ratio of saturated PLFA to monounsaturated PLFA (S/M) as indicators of microbial stress were controlled by pH, but high pH was not conducive to microorganisms in this area. Meanwhile, Cy/Pr in all communities was >0.1, indicating that microorganisms were under environmental stress. Therefore, the further ecological restoration of degraded karst communities is needed to improve their microbial communities.


2021 ◽  
Vol 49 (4) ◽  
pp. 12532
Author(s):  
Ali I. MALLANO ◽  
Xianli ZHAO ◽  
Yanling SUN ◽  
Guangpin JIANG ◽  
Huang CHAO

Continuous cropping systems are the leading cause of decreased soil biological environments in terms of unstable microbial population and diversity index. Nonetheless, their responses to consecutive peanut monocropping cycles have not been thoroughly investigated. In this study, the structure and abundance of microbial communities were characterized using pyrosequencing-based approach in peanut monocropping cycles for three consecutive years. The results showed that continuous peanut cultivation led to a substantial decrease in soil microbial abundance and diversity from initial cropping cycle (T1) to later cropping cycle (T3). Peanut rhizosphere soil had Actinobacteria, Protobacteria, and Gemmatimonadetes as the major bacterial phyla. Ascomycota, Basidiomycota were the major fungal phylum, while Crenarchaeota and Euryarchaeota were the most dominant phyla of archaea. Several bacterial, fungal and archaeal taxa were significantly changed in abundance under continuous peanut cultivation. Bacterial orders, Actinomycetales, Rhodospirillales and Sphingomonadales showed decreasing trends from T1>T2>T3. While, pathogenic fungi Phoma was increased and beneficial fungal taxa Glomeraceae decreased under continuous monocropping. Moreover, Archaeal order Nitrososphaerales observed less abundant in first two cycles (T1&T2), however, it increased in third cycle (T3), whereas, Thermoplasmata exhibit decreased trends throughout consecutive monocropping. Taken together, we have shown the taxonomic profiles of peanut rhizosphere communities that were affected by continuous peanut monocropping. The results obtained from this study pave ways towards a better understanding of the peanut rhizosphere soil microbial communities in response to continuous cropping cycles, which could be used as bioindicator to monitor soil quality, plant health and land management practices.


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.


el–Hayah ◽  
2012 ◽  
Vol 1 (4) ◽  
Author(s):  
Prihastuti Prihastuti

<p>Soils are made up of organic and an organic material. The organic soil component contains all the living creatures in the soil and the dead ones in various stages of decomposition.  Biological activity in soil helps to recycle nutrients, decompose organic matter making nutrient available for plant uptake, stabilize humus, and form soil particles.<br />The extent of the diversity of microbial in soil is seen to be critical to the maintenance of soil health and quality, as a wide range of microbial is involved in important soil functions.  That ecologically managed soils have a greater quantity and diversity of soil microbial. The two main drivers of soil microbial community structure, i.e., plant type and soil type, are thought to exert their function in a complex manner. The fact that in some situations the soil and in others the plant type is the key factor determining soil microbial diversity is related to their complexity of the microbial interactions in soil, including interactions between microbial and soil and microbial and plants. <br />The basic premise of organic soil stewardship is that all plant nutrients are present in the soil by maintaining a biologically active soil environment. The diversity of microbial communities has on ecological function and resilience to disturbances in soil ecosystems. Relationships are often observed between the extent of microbial diversity in soil, soil and plant quality and ecosystem sustainability. Agricultural management can be directed toward maximizing the quality of the soil microbial community in terms of disease suppression, if it is possible to shift soil microbial communities.</p><p>Keywords: structure, microbial, implication, sustainable agriculture<br /><br /></p>


Author(s):  
Aiai Xu ◽  
Jie Liu ◽  
Zhiying Guo ◽  
Changkun Wang ◽  
Kai Pan ◽  
...  

It is critical to identify the assembly processes and determinants of soil microbial communities to better predict soil microbial responses to environmental change in arid and semiarid areas. Here, soils from 16 grassland-only, 9 paired grassland and farmland, and 16 farmland-only sites were collected across the central Inner Mongolia Plateau covering a steep environmental gradient. Through analyzing the paired samples, we discovered that land uses had strong effects on soil microbial communities, but weak effects on their assembly processes. For all samples, although no environmental variables were significantly correlated with the net relatedness index (NRI), both the nearest taxon index (NTI) and the β-nearest taxon index (βNTI) were most related to mean annual precipitation (MAP). With the increase of MAP, soil microbial taxa at the tips of the phylogenetic tree were more clustered, and the contribution of determinism increased. Determinism (48.6%), especially variable selection (46.3%), and stochasticity (51.4%) were almost equal in farmland, while stochasticity (75.0%) was dominant in grassland. Additionally, Mantel tests and redundancy analyses (RDA) revealed that the main determinants of soil microbial community structure were MAP in grassland, but mean annual temperature (MAT) in farmland. MAP and MAT were also good predictors of the community composition (the top 200 dominant OTUs) in grassland and farmland, respectively. Collectively, in arid and semiarid areas, soil microbial communities were more sensitive to environmental change in farmland than in grassland, and unlike the major impact of MAP on grassland microbial communities, MAT was the primary driver of farmland microbial communities. Importance As one of the most diverse organisms, soil microbes play indispensable roles in many ecological processes in arid and semiarid areas with limited macrofaunal and plant diversity, yet the mechanisms underpinning soil microbial community are not fully understood. In this study, soil microbial communities were investigated along a 500 km transect covering a steep environmental gradient across farmland and grassland in the areas. The results showed that precipitation was the main factor mediating the assembly processes. Determinism was more influential in farmland, and variable selection of farmland was twice that of grassland. Temperature mainly drove farmland microbial communities, while precipitation mainly affected grassland microbial communities. These findings provide new information about the assembly processes and determinants of soil microbial communities in arid and semiarid areas, consequently improving the predictability of the community dynamics, which have implications for sustaining soil microbial diversity and ecosystem functioning, particularly under global climate change conditions.


2020 ◽  
Author(s):  
Huiqin Xie ◽  
Yongli Ku ◽  
Xiangna Yang ◽  
Le Cao ◽  
Xueli Mei ◽  
...  

Abstract Background: Melon (Cucumis melo L.) is one of the most important fruit crops grown in China. However, the yield and quality of melon have significantly declined under continuous cropping. Phenolic acids are believed to be associated with the continuous monocropping obstacle (CMO) and can influence plant microbe interactions. Coumaric acid (CA) is one of the major phenolic acids found in melon root exudates. The objectives of this study were to estimate the elimination of CA by the soil bacterium K3 as well as its effects on mitigating melon CMO. CA degradation was investigated by monitoring the CA retained in the growth medium using high performance liquid chromatography (HPLC). The effects of CA and K3 on rhizosphere soil microbial communities were investigated by the spread plate method and Illumina MiSeq sequencing. Furthermore, the effects of CA and K3 on melon seedling growth were measured under potted conditions. The changes in soil enzymes and fruit quality under K3 amendment were examined in a greenhouse experiment. Result:The results suggest that the addition of CA had the same result as the CMO, such as deterioration of the microbial community and slower growth of melon plants. HPLC and microbial analysis showed that K3 had a pronounced ability to decompose CA and could improve the soil microbial community environment. Soil inoculation with K3 agent could significantly improve the fruit quality of melon.Conclusion: Our results show that the effects of K3 in the soil are reflected by changes in populations and diversity of soil microbes and suggest that deterioration of microbial communities in soil might be associated with the growth constraint of melon in continuous monoculture systems.


mSystems ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Arunima Bhattacharjee ◽  
Dusan Velickovic ◽  
Thomas W. Wietsma ◽  
Sheryl L. Bell ◽  
Janet K. Jansson ◽  
...  

ABSTRACT Understanding the basic biology that underpins soil microbiome interactions is required to predict the metaphenomic response to environmental shifts. A significant knowledge gap remains in how such changes affect microbial community dynamics and their metabolic landscape at microbially relevant spatial scales. Using a custom-built SoilBox system, here we demonstrated changes in microbial community growth and composition in different soil environments (14%, 24%, and 34% soil moisture), contingent upon access to reservoirs of nutrient sources. The SoilBox emulates the probing depth of a common soil core and enables determination of both the spatial organization of the microbial communities and their metabolites, as shown by confocal microscopy in combination with mass spectrometry imaging (MSI). Using chitin as a nutrient source, we used the SoilBox system to observe increased adhesion of microbial biomass on chitin islands resulting in degradation of chitin into N-acetylglucosamine (NAG) and chitobiose. With matrix-assisted laser desorption/ionization (MALDI)-MSI, we also observed several phospholipid families that are functional biomarkers for microbial growth on the chitin islands. Fungal hyphal networks bridging different chitin islands over distances of 27 mm were observed only in the 14% soil moisture regime, indicating that such bridges may act as nutrient highways under drought conditions. In total, these results illustrate a system that can provide unprecedented spatial information about interactions within soil microbial communities as a function of changing environments. We anticipate that this platform will be invaluable in spatially probing specific intra- and interkingdom functional relationships of microbiomes within soil. IMPORTANCE Microbial communities are key components of the soil ecosystem. Recent advances in metagenomics and other omics capabilities have expanded our ability to characterize the composition and function of the soil microbiome. However, characterizing the spatial metabolic and morphological diversity of microbial communities remains a challenge due to the dynamic and complex nature of soil microenvironments. The SoilBox system, demonstrated in this work, simulates an ∼12-cm soil depth, similar to a typical soil core, and provides a platform that facilitates imaging the molecular and topographical landscape of soil microbial communities as a function of environmental gradients. Moreover, the nondestructive harvesting of soil microbial communities for the imaging experiments can enable simultaneous multiomics analysis throughout the depth of the SoilBox. Our results show that by correlating molecular and optical imaging data obtained using the SoilBox platform, deeper insights into the nature of specific soil microbial interactions can be achieved.


2011 ◽  
Vol 50 (No. 4) ◽  
pp. 141-148 ◽  
Author(s):  
J. Hofman ◽  
J. Švihálek ◽  
I. Holoubek

In our case study, we measured the functional diversity of the microbial communities of twelve soils from the small natural area to assess if this assay is suitable for routine monitoring of soil biological quality. We found the BIOLOG assay meets especially practical benefits in routine monitoring of soils being simple and quick assay. However, we confirmed the ambiguity about the most appropriate analysis of the BIOLOG multivariate data and about the best parameter, which can be derived from the assay. The different analyses of the data were examined and various parameters derived from the BIOLOG assay were comparatively used to contribute to the discussion of how the data should be evaluated. We showed that not-normalized raw absorbances or trapezoid areas should be used for calculation of diversity index if the inoculum was standardized. There was no single answer to what parameter provided more correct results in the multivariate statistical analysis. Evaluating at least one not-normalized (e.g. trapezoid area) and one normalized parameter (e.g. absorbances read in fixed AWCD) was strongly suggested keeping in mind that they reveal different information.


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