scholarly journals Anthropogenic disturbances consistently favor the high-yield strategists of soil bacterial community in the Eurasian steppe

2021 ◽  
Vol 71 (1) ◽  
Author(s):  
Yi Fan ◽  
Tingting Li ◽  
Wei Liu ◽  
Minjie Xu ◽  
Shuang Pang ◽  
...  

Abstract Purpose Multiple anthropogenic disturbances, such as climate warming and nitrogen deposition are affecting terrestrial ecosystems. Different disturbances may have some consistent effects on the soil microbial community, which remains largely unexplored. Methods We mimicked 16 anthropogenic disturbances in a steppe ecosystem, and measured the absolute abundance and taxonomic composition of soil bacterial communities with qPCR and amplicon sequencing, respectively. Results We found that while the absolute abundance of each of the four dominant bacterial phyla did not show a consistent response to these disturbances, that of the five subdominant phyla showed a consistent increase. Meanwhile, these disturbances consistently stimulated the relative abundances of metabolic functions for high-growth-yield, including the transport/metabolism of amino acids and carbohydrates. Stochastic processes (e.g., random birth) played more critical roles in structuring the subdominant than dominant phyla, and the disturbances promoted the stochastic processes. Conclusions Overall, the high-yield traits and stochasticity of subdominant phyla led to their positive responses to disturbances. Furthermore, our findings indicate that the intensifying human activities are likely to cause a high-yield-strategies-toward shift in soil microbial composition in the Eurasian steppe ecosystem.

2020 ◽  
Author(s):  
Han-Wen Deng ◽  
Xin-Fu Bai ◽  
Ping Zhu ◽  
Yu-Meng Lu ◽  
Lei Ji ◽  
...  

Abstract Background Grazing exclusion is a common grassland management strategy for restoring degraded grasslands. Its effectiveness on optimizing plant species community, increasing vegetation diversity and biomass, improving soil fertility, has been widely documented in literatures. However, little is known on the responses of the absolute abundance and the ecological functions of soil bacterial community to long-term grazing exclusion. Result In this study, the absolute abundance, diversity, and ecological functions of soil bacterial community were determined by the high-throughput absolute quantitative sequencing technology on a long-term grazing exclusion (40 years, GE) area and three free grazing areas (FGs) within a Leymus chinensis steppe of Inner Mongolia, China, and analyzed the driving forces leading to the variations in soil bacterial community and functions. Our results showed that there was significantly higher soil bacterial abundance in the GE than the FGs along with corresponding variations in vegetation and soil properties. With the decrease of vegetation aboveground biomass, the absolute abundance of soil bacterial community also decreased. Among the phyla of the soil bacterial communities, the relative abundances of Chloroflexi and Firmicutes phyla were especially lower, and that of Verrucomicrobia phylum was higher in the GE than the FGs; the absolute abundances of Euryarchaeota and Microgenomates phyla were especially higher in the GE than the FGs. Conclusions This study suggested that long-term grazing exclusion significantly increased the absolute abundance, changed soil bacterial composition, and especially enhanced bacterial motility and chemotaxis. In particular, soil organic matter was the important agent to influence and connect vegetation and soil. This work will enrich our understanding of the responses of absolute abundance, diversity, and function of the soil bacterial community to long-term grazing exclusion, and help the evaluation of grassland degradation degree and restoration strategy effectiveness.


Diversity ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 84
Author(s):  
Andéole Niyongabo Turatsinze ◽  
Baotian Kang ◽  
Tianqi Zhu ◽  
Fujiang Hou ◽  
Saman Bowatte

Soil microbial composition and diversity are widely recognized for their role in ecological functioning. This study examined the differences of soil microbial communities between two seasonally grazed grasslands. The study area was in the Gansu red deer farm located on the Qilian Mountain range in the Gansu province of northwestern China. This farm adopted a seasonal rotation grazing system whereby grasslands at higher altitudes are grazed in summer (SG), whilst grasslands at lower altitudes are grazed in winter (WG). The soil bacterial and fungal communities were examined by Illumina MiSeq sequencing. We found that soil water content (SWC), organic carbon (OC), total carbon (TC), and total nitrogen (TN) were significantly higher, whereas the C/N ratio was significantly lower in SG than WG pastures. The α-diversity of bacteria was greater than that of fungi in both pastures, while both bacterial and fungal α-diversity were not significantly different between the pastures. The bacterial β-diversity was significantly different between the pastures, but fungal β-diversity was not. The bacterial phylum Actinobacteria and fungal phylum Ascomycota were dominant in both pastures. The relative abundance of Actinobacteria in soil was significantly higher in WG pastures, whereas the relative abundance of Proteobacteria in soil was significantly higher in SG pastures. Significant correlations between bacterial and fungal phyla and soil properties were observed, but this varied between the two grasslands. This study showed that distinct microbial community structures developed in two pastures within the same geographic location that were grazed in different seasons.


Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 797 ◽  
Author(s):  
Tan ◽  
Kan ◽  
Su ◽  
Liu ◽  
Zhang

Soil microbes are of great significance to driving the biogeochemical cycles and are affected by multiple factors, including urbanization. However, the response of soil microbes to urbanization remains unclear. Therefore, we designed an urban-to-rural gradient experiment to investigate the response of soil microbial composition and diversity to urbanization. Here, we used a high-throughput sequencing method to analyze the biotic and abiotic effects on soil microbial composition and diversity along the urban-to-rural gradient. Our results showed that soil bacterial diversity was the highest in urban areas, followed by suburban areas, and was the lowest in exurbs; however, fungal diversity did not vary significantly among the three areas. Plant traits, i.e., tree richness, shrub richness, the number of tree stems, diameter at breast height of trees, and soil properties, i.e., pH, soil organic carbon, soil exchangeable calcium and magnesium, and soil water content, were only significantly influenced bacterial diversity, but not fungal diversity. The effect of trees and shrubs was higher than that of herbs on microbial composition. Soil organic carbon, pH, soil available nitrogen, soil exchangeable calcium, and magnesium were the major soil factors influencing the soil bacterial and fungal composition. Soil properties had a greater influence on bacterial than on fungal composition at genus level, while plant traits contributed more to fungal than to bacterial composition at genus level. Our study suggests that the urban-to-rural gradient affect the composition and diversity of bacterial community as well as the fungal composition, but not the fungal diversity.


2021 ◽  
Vol 12 (1) ◽  
pp. 157-172
Author(s):  
Shankar G. Shanmugam ◽  
Normie W. Buehring ◽  
Jon D. Prevost ◽  
William L. Kingery

Our understanding on the effects of tillage intensity on the soil microbial community structure and composition in crop production systems are limited. This study evaluated the soil microbial community composition and diversity under different tillage management systems in an effort to identify management practices that effectively support sustainable agriculture. We report results from a three-year study to determine the effects on changes in soil microbial diversity and composition from four tillage intensity treatments and two residue management treatments in a corn-soybean production system using Illumina high-throughput sequencing of 16S rRNA genes. Soil samples were collected from tillage treatments at locations in the Southern Coastal Plain (Verona, Mississippi, USA) and Southern Mississippi River Alluvium (Stoneville, Mississippi, USA) for soil analysis and bacterial community characterization. Our results indicated that different tillage intensity treatments differentially changed the relative abundances of bacterial phyla. The Mantel test of correlations indicated that differences among bacterial community composition were significantly influenced by tillage regime (rM = 0.39, p ≤ 0.0001). Simpson’s reciprocal diversity index indicated greater bacterial diversity with reduction in tillage intensity for each year and study location. For both study sites, differences in tillage intensity had significant influence on the abundance of Proteobacteria. The shift in the soil bacterial community composition under different tillage systems was strongly correlated to changes in labile carbon pool in the system and how it affected the microbial metabolism. This study indicates that soil management through tillage intensity regime had a profound influence on diversity and composition of soil bacterial communities in a corn-soybean production system.


2021 ◽  
Vol 7 (7) ◽  
pp. 539
Author(s):  
Tamás Plaszkó ◽  
Zsolt Szűcs ◽  
Gábor Vasas ◽  
Sándor Gonda

Plants heavily rely on chemical defense systems against a variety of stressors. The glucosinolates in the Brassicaceae and some allies are the core molecules of one of the most researched such pathways. These natural products are enzymatically converted into isothiocyanates (ITCs) and occasionally other defensive volatile organic constituents (VOCs) upon fungal challenge or tissue disruption to protect the host against the stressor. The current review provides a comprehensive insight on the effects of the isothiocyanates on fungi, including, but not limited to mycorrhizal fungi and pathogens of Brassicaceae. In the review, our current knowledge on the following topics are summarized: direct antifungal activity and the proposed mechanisms of antifungal action, QSAR (quantitative structure-activity relationships), synergistic activity of ITCs with other agents, effects of ITCs on soil microbial composition and allelopathic activity. A detailed insight into the possible applications is also provided: the literature of biofumigation studies, inhibition of post-harvest pathogenesis and protection of various products including grains and fruits is also reviewed herein.


2021 ◽  
Vol 9 (2) ◽  
pp. 211
Author(s):  
Jie Gao ◽  
Miao Liu ◽  
Sixue Shi ◽  
Ying Liu ◽  
Yu Duan ◽  
...  

In this study, we analyzed microbial community composition and the functional capacities of degraded sites and restored/natural sites in two typical wetlands of Northeast China—the Phragmites marsh and the Carex marsh, respectively. The degradation of these wetlands, caused by grazing or land drainage for irrigation, alters microbial community components and functional structures, in addition to changing the aboveground vegetation and soil geochemical properties. Bacterial and fungal diversity at the degraded sites were significantly lower than those at restored/natural sites, indicating that soil microbial groups were sensitive to disturbances in wetland ecosystems. Further, a combined analysis using high-throughput sequencing and GeoChip arrays showed that the abundance of carbon fixation and degradation, and ~95% genes involved in nitrogen cycling were increased in abundance at grazed Phragmites sites, likely due to the stimulating impact of urine and dung deposition. In contrast, the abundance of genes involved in methane cycling was significantly increased in restored wetlands. Particularly, we found that microbial composition and activity gradually shifts according to the hierarchical marsh sites. Altogether, this study demonstrated that microbial communities as a whole could respond to wetland changes and revealed the functional potential of microbes in regulating biogeochemical cycles.


2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Ming-Yi Chou ◽  
Justine Vanden Heuvel ◽  
Terrence H. Bell ◽  
Kevin Panke-Buisse ◽  
Jenny Kao-Kniffin

2021 ◽  
Vol 52 (2) ◽  
pp. 239-250
Author(s):  
X.J. He ◽  
W.W. Zhu ◽  
F.Z. Wu

We studied the effects of 7-crop rotations and continuous - monocropping systems on soil microorganism and its feedback. The results showed that absolute abundance of soil bacteria (Pseudomonas and Bacillus) in tomato - celery - cucumber - cabbage and cucumber - tomato - cucumber - cabbage rotation were significantly higher than control (CK). Absolute abundance of soil fungi in tomato - celery - cucumber - cabbage, kidney bean - celery - cucumber - cabbage, cucumber - kidney bean - cucumber - cabbage and cucumber - tomato - cucumber - cabbage rotation were significantly higher than CK. Dry weight of cucumber seedlings was significantly positively correlated with bacterial (Pseudomonas and Bacillus) abundance, and negatively correlated with fungal count. The results of inoculation with Fusarium oxysporum f.sp. cucumerinum showed that plant dry weight of cucumber seedlings in tomato - celery - cucumber - cabbage, cucumber - kidney bean - cucumber - cabbage, cucumber - tomato - cucumber - cabbage rotation soil was significantly higher than other treatments, and their disease index was significantly lower than other treatments. There was no significant difference in dry weight of cucumber seedlings in rotation and CK in the soil sterilization test. The results of plant - soil feedback experiment showed that soil microbial changes caused by different rotation patterns had a positive feedback effect on growth of cucumber seedlings.


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