scholarly journals Straw Mulching and Nitrogen Fertilization Affect Diazotroph Communities in Wheat Rhizosphere

2021 ◽  
Vol 12 ◽  
Author(s):  
Songhe Chen ◽  
Xiaoling Xiang ◽  
Hongliang Ma ◽  
Petri Penttinen ◽  
Jiarong Zhao ◽  
...  
Keyword(s):  
Community Composition ◽  
C:N Ratio ◽  
N Fertilization ◽  
Organic Substrates ◽  
Biological Fixation ◽  
Available Nitrogen ◽  
Straw Mulching ◽  
Wheat Rhizosphere ◽  
Α Diversity ◽  
Fertilization Level

Diazotrophs that carry out the biological fixation of atmospheric dinitrogen (N2) replenish biologically available nitrogen (N) in soil and are influenced by the input of inorganic and organic substrates. To date, little is known about the effects of combined organic substrate addition and N fertilization on the diazotroph community composition and structure in purple soils. We investigated the effects of N fertilization and straw mulching on diazotroph communities by quantifying and sequencing the nifH gene in wheat rhizosphere. The abundance and richness of diazotrophs were greater the higher the fertilization level in the mulched treatments, whereas in the nonmulched treatments (NSMs), richness was lowest with the highest N fertilization level. The abundance and α-diversity of diazotrophs correlated with most of the soil properties but not with pH. At the genus level, the relative abundances of Azospirillum, Bacillus, and Geobacter were higher in the NSMs and those of Pseudacidovorax, Skermanella, Azospira, Paraburkholderia, Azotobacter, Desulfovibrio, Klebsiella, and Pelomonas in the mulched treatments. The differences in community composition between the mulched and the NSMs were associated with differences in soil temperature and soil organic carbon and available potassium contents and C:N ratio. Overall, straw mulching and N fertilization were associated with changes in diazotroph community composition and higher abundance of nifH gene in alkaline purple soils.

scholarly journals Straw mulching and nitrogen application altered ammonia oxidizers communities and improved soil quality in the alkaline purple soil of southwest China

AMB Express ◽  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Songhe Chen ◽  
Rencai Gao ◽  
Xiaoling Xiang ◽  
Hongkun Yang ◽  
Hongliang Ma ◽  
...  
Keyword(s):  
Soil Quality ◽  
Ammonia Oxidation ◽  
Management Strategies ◽  
Rflp Analysis ◽  
Available Phosphorus ◽  
Purple Soil ◽  
Ammonia Oxidizers ◽  
Nitrogen Application ◽  
Available Nitrogen ◽  
Straw Mulching

AbstractMicrobe-mediated ammonia oxidation is a key process in soil nitrogen cycle. However, the effect of maize straw mulching on the ammonia oxidizers in the alkaline purple soil remains largely unknown. A three-year positioning experiment was designed as follows: straw mulching measures as the main-plot treatment and three kinds of nitrogen application as the sub-plot treatment. We found the contents of soil organic carbon (SOC), total nitrogen (TN), available potassium (AK), available nitrogen (AN), available phosphorus (AP), and NH4+-N were increased after straw mulching and nitrogen application in alkaline purple soil, so did the amoA genes abundance of ammonia-oxidizing archaeal (AOA) and bacterial (AOB). Terminal restriction fragment length polymorphism (T-RFLP) analysis revealed that Thaumarchaeote (448-bp T-RF) was dominated the AOA communities, whereas Nitrosospira sp (111-bp T-RF) dominated the AOB communities. The community compositions of both AOA and AOB were altered by straw mulching and nitrogen application in alkaline purple soil, however, the AOB communities was more responsive than AOA communities to the straw mulching and nitrogen application. Further analysis indicated that SOC and AP were the main factors affecting the abundance and community compositions of AOA and AOB in alkaline purple soil. The present study reported that straw mulching and nitrogen strategies differently shape the soil ammonia oxidizers community structure and abundance, which should be considered when evaluating agricultural management strategies regarding their sustainability and soil quality.

Grazing intensity rather than host plant’s palatability shape the community of arbuscular mycorrhizal fungi in a steppe grassland

2021 ◽  
Author(s):  
Maede Faghihinia ◽  
Yi Zou ◽  
Yongfei Bai ◽  
Martin Dudáš ◽  
Rob Marrs ◽  
...  
Keyword(s):  
Arbuscular Mycorrhizal Fungi ◽  
Community Composition ◽  
Mycorrhizal Fungi ◽  
Rhizosphere Soil ◽  
Grazing Intensity ◽  
Arbuscular Mycorrhizal ◽  
Grass Species ◽  
Α Diversity ◽  
Steppe Grassland

Abstract Arbuscular mycorrhizal fungi (AMF) are the predominant type of mycorrhizal fungi in roots and rhizosphere soil of grass species worldwide. Grasslands are currently experiencing increasing grazing pressure, but it is not yet clear how grazing intensity and host plant grazing preference by large herbivores interact with soil- and root-associated AMF communities. Here, we tested whether the diversity and community composition of AMF in the roots and rhizosphere soil of two dominant perennial grasses grazed differently by livestock change in response to grazing intensity. We conducted a study in a long-term field experiment in which seven levels of field-manipulated grazing intensities were maintained for 13 years in a typical steppe grassland in northern China. We extracted DNA from the roots and rhizosphere soil of two dominant grasses, Leymus chinense (Trin.) Tzvel. and Stipa grandis P. Smirn, with contrasting grazing preference by sheep. AMF DNA from root and soil samples were then subjected to molecular analysis. Our results showed that AMF α-diversity (richness) at the virtual taxa (VT) level varied as a function of grazing intensity. Different VTs showed completely different responses along the gradient, one increasing, one decreasing and others showing no response. Glomeraceae was the most abundant AMF family along the grazing gradient, which fits well with the theory of disturbance tolerance of this group. In addition, sheep grazing preference for host plants did not explain a considerable variation in AMF α-diversity. However, the two grass species exhibited different community composition in their roots and rhizosphere soils. Roots exhibited a lower α-diversity and higher β-diversity within the AMF community than soils. Overall, our results suggest that long-term grazing intensity might have changed the abundance of functionally-diverse AMF taxa in favor of those with disturbance-tolerant traits. We suggest our results would be useful in informing the choice of mycorrhizal fungi indicator variables when assessing the impacts of grassland management choices on grassland ecosystem functioning.

scholarly journals Effects of nitrogen enrichment on zooplankton biomass and N:P recycling ratios across a DOC gradient in northern-latitude lakes

Hydrobiologia ◽  
2021 ◽  
Author(s):  
A.-K. Bergström ◽  
A. Deininger ◽  
A. Jonsson ◽  
J. Karlsson ◽  
T. Vrede
Keyword(s):  
Community Composition ◽  
Resource Use ◽  
Phytoplankton Biomass ◽  
Phytoplankton Community ◽  
N Fertilization ◽  
Zooplankton Biomass ◽  
Nitrogen Enrichment ◽  
C:N:P Stoichiometry ◽  
Food Quantity ◽  
N Enrichment

AbstractWe used data from whole-lake studies to assess how changes in food quantity (phytoplankton biomass) and quality (phytoplankton community composition, seston C:P and N:P) with N fertilization affect zooplankton biomass, community composition and C:N:P stoichiometry, and their N:P recycling ratio along a gradient in lake DOC concentrations. We found that despite major differences in phytoplankton biomass with DOC (unimodal distributions, especially with N fertilization), no major differences in zooplankton biomass were detectable. Instead, phytoplankton to zooplankton biomass ratios were high, especially at intermediate DOC and after N fertilization, implying low trophic transfer efficiencies. An explanation for the observed low phytoplankton resource use, and biomass responses in zooplankton, was dominance of colony forming chlorophytes of reduced edibility at intermediate lake DOC, combined with reduced phytoplankton mineral quality (enhanced seston N:P) with N fertilization. N fertilization, however, increased zooplankton N:P recycling ratios, with largest impact at low DOC where phytoplankton benefitted from light sufficiently to cause enhanced seston N:P. Our results suggest that although N enrichment and increased phytoplankton biomass do not necessarily increase zooplankton biomass, bottom-up effects may still impact zooplankton and their N:P recycling ratio through promotion of phytoplankton species of low edibility and altered mineral quality.

scholarly journals The roles of environmental variation and spatial distance in explaining diversity and biogeography of soil denitrifying communities in remote Tibetan wetlands

2020 ◽  
Vol 96 (5) ◽  
Author(s):  
Xiaoliang Jiang ◽  
Wenzhi Liu ◽  
Lunguang Yao ◽  
Guihua Liu ◽  
Yuyi Yang
Keyword(s):  
Electrical Conductivity ◽  
Soil Moisture ◽  
Soil Temperature ◽  
Community Composition ◽  
Environmental Filtering ◽  
Operational Taxonomic Unit ◽  
Amplicon Sequencing ◽  
Spatial Distance ◽  
Wetland Type ◽  
Α Diversity

ABSTRACT The relative importance of local environments and dispersal limitation in shaping denitrifier community structure remains elusive. Here, we collected soils from 36 riverine, lacustrine and palustrine wetland sites on the remote Tibetan Plateau and characterized the soil denitrifier communities using high-throughput amplicon sequencing of the nirS and nirK genes. Results showed that the richness of nirS-type denitrifiers in riverine wetlands was significantly higher than that in lacustrine wetlands but not significantly different from that in palustrine wetlands. There was no clear distinction in nir community composition among the three kinds of wetlands. Irrespective of wetland type, the soil denitrification rate was positively related to the abundance, but not the α-diversity, of denitrifying communities. Soil moisture, carbon availability and soil temperature were the main determinants of diversity [operational taxonomic unit (OTU) number] and abundance of thenirS-type denitrifier community, while water total organic carbon, soil NO3– and soil moisture were important in controlling nirK-type denitrifier diversity and abundance. The nirS community composition was influenced by water electrical conductivity, soil temperature and water depth, while the nirK community composition was affected by soil electrical conductivity. Spatial distance explained more variation in the nirS community composition than in the nirK community composition. Our findings highlight the importance of both environmental filtering and spatial distance in explaining diversity and biogeography of soil nir communities in remote and relatively undisturbed wetlands.

The role of copepod-dominated meiofauna in the mineralization of organic matter in a cold marine mesocosm

1999 ◽  
Vol 56 (10) ◽  
pp. 1938-1948
Author(s):  
Serge Parent ◽  
Antoine Morin
Keyword(s):  
Particle Size ◽  
C:N Ratio ◽  
Organic Substrates ◽  
Mineralization Rate ◽  
Nutrient Regeneration ◽  
Sand Filters ◽  
Harpacticoid Copepods ◽  
Large Populations ◽  
Mineralization Of Organic Matter

Large populations of meiofauna are found in the sand filters of the St. Lawrence mesocosm at the Montreal Biodome. Three 30-day experiments were conducted in heterotrophic microcosms to quantify how populations of micro- and meio-faunal organisms affect mineralization using the apparent mineralization rate (AMR), i.e., nitrate production, as a proxy. Tryptone, mesocosm detritus, and fishmeal were used as organic substrates (C:N ratios 4-8). Harpacticoid copepods dominated the meiofauna in numbers (87%) and biomass (90%). AMR was inversely related to meiofaunal mass and not related to ciliate density. Through grazing, 1 g meiofaunal dry mass·m-2 reduced the AMR of tryptone by 42%, of detritus by 9.4%, and of fishmeal by 2.7%. Particle size affected the effect of meiofauna, whereas the C:N ratio affected the AMR. The scarcity of nematodes, which are known to stimulate mineralization, may explain these results. Copepod-dominated meiofauna decrease nutrient regeneration rates in heterotrophic habitats when C:N ratios are low.

scholarly journals Gut microbiota structure differs between honey bees in winter and summer

2019 ◽  
Author(s):  
Lucie Kešnerová ◽  
Olivier Emery ◽  
Michaël Troilo ◽  
Joanito Liberti ◽  
Berra Erkosar ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Community Composition ◽  
Honey Bees ◽  
Low Complexity ◽  
Α Diversity ◽  
Bee Health ◽  
Health And Disease ◽  
Colony Survival ◽  
Future Work

AbstractAdult honey bees harbor a specialized gut microbiota of relatively low complexity. While seasonal differences in community composition have been reported, previous studies have focused on compositional changes rather than differences in absolute bacterial loads. Moreover, little is known about the gut microbiota of winter bees, which live much longer than bees during the foraging season, and which are critical for colony survival. We quantified seven core members of the bee gut microbiota in a single colony over two years and characterized the community composition in 14 colonies during summer and winter. Our data shows that total bacterial loads substantially differ between foragers, nurses, and winter bees. Long-lived winter bees had the highest bacterial loads and the lowest community α-diversity, with a characteristic shift towards high levels of Bartonella and Commensalibacter, and a reduction of opportunistic colonizers. Using gnotobiotic bee experiments, we show that diet is a major contributor to the observed differences in bacterial loads. Overall, our study reveals that the gut microbiota of winter bees is remarkably different from foragers and nurses. Considering the importance of winter bees for colony survival, future work should focus on the role of the gut microbiota in winter bee health and disease.

scholarly journals Evaluation of Three Prokaryote Primers for Identification of Prokaryote Community Structure and Their Abode Preference in Three Distinct Wetland Ecosystems

2021 ◽  
Vol 12 ◽  
Author(s):  
Kavita Kumari ◽  
Malay Naskar ◽  
Md. Aftabuddin ◽  
Soma Das Sarkar ◽  
Bandana Das Ghosh ◽  
...  
Keyword(s):  
Community Structure ◽  
Community Composition ◽  
Microbial Community Composition ◽  
Distinct Pattern ◽  
Freshwater Wetland ◽  
Wetland Ecosystem ◽  
Differential Abundance ◽  
Abundance Pattern ◽  
Α Diversity ◽  
Study Results

The ultimate role of prokaryote (bacteria and archaea), the decomposer of the wetland ecosystem, depends on its community structure and its interaction with the environment. The present study has used three universal prokaryote primers to compare prokaryote community structure and diversity of three distinctly different wetlands. The study results revealed that α-diversity indices and phylogenetic differential abundance patterns did not differ significantly among primers, but they did differ significantly across wetlands. Microbial community composition revealed a distinct pattern for each primer in each wetland. Overall comparison of prokaryote communities in sediments of three wetlands revealed the highest prokaryote richness and diversity in Bhomra (freshwater wetland) followed by Malencho (brackish-water wetland) and East Kolkata wetland (EKW) (sewage-fed wetland). Indicator genus analysis identified 21, 4, and 29 unique indicator genera, having preferential abode for Bhomra, EKW, and Malencho, respectively. Prediction of potential roles of these microbes revealed a preference for sulfate-reducing microbes in Malencho and methanogens in Bhomra. The distinct phylogenetic differential abundance pattern, microbial abode preference, and their potential functional role predict ecosystem variables shaping microbial diversity. The variation in community composition of prokaryotes in response to ecosystem variables can serve as the most sensitive bioindicator of wetland ecosystem assessment and management.

scholarly journals Long-term warming and nitrogen fertilization affect C-, N- and P-acquiring hydrolase and oxidase activities in winter wheat monocropping soil

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chuang Zhang ◽  
Wenxu Dong ◽  
Kiril Manevski ◽  
Wenpei Hu ◽  
Arbindra Timilsina ◽  
...  
Keyword(s):  
Agricultural Soils ◽  
C:N Ratio ◽  
Resource Limitation ◽  
N Fertilization ◽  
Organic N ◽  
Resource Limitations ◽  
The North ◽  
The Relationship ◽  
Enzyme Ratio

AbstractThe enzymatic activities and ratios are critical indicators for organic matter decomposition and provide potentially positive feedback to carbon (C) loss under global warming. For agricultural soils under climate change, the effect of long-term warming on the activities of oxidases and hydrolases targeting C, nitrogen (N) and phosphorus (P) and their ratios is unclear, as well as whether and to what extend the response is modulated by long-term fertilization. A 9-year field experiment in the North China Plain, including an untreated control, warming, N fertilization, and combined (WN) treatment plots, compared the factorial effect of warming and fertilization. Long-term warming interacted with fertilization to stimulate the highest activities of C, N, and P hydrolases. Activities of C and P hydrolase increased from 8 to 69% by N fertilization, 9 to 53% by warming, and 28 to 130% by WN treatment compared to control, whereas the activities of oxidase increased from 4 to 16% in the WN soils. Both the warming and the WN treatments significantly increased the enzymatic C:N ratio from 0.06 to 0.16 and the vector length from 0.04 to 0.12 compared to the control soil, indicating higher energy and resource limitation for the soil microorganisms. Compared to WN, the warming induced similar ratio of oxidase to C hydrolase, showing a comparable ability of different microbial communities to utilize lignin substrates. The relationship analyses showed mineralization of organic N to mediate the decomposition of lignin and enzyme ratio in the long-term warming soil, while N and P hydrolases cooperatively benefited to induce more oxidase productions in the soil subject to both warming and N fertilization. We conclude that coupled resource limitations induced microbial acclimation to long-term warming in the agricultural soils experiencing high N fertilizer inputs.

scholarly journals Drivers of Microbial Community Structure in Surface Sediment Aross Bohai Sea

2020 ◽  
Author(s):  
lei chen ◽  
Yuntao Li ◽  
Mingpeng Wang ◽  
Weitao Shang ◽  
Jianhui Tang ◽  
...  
Keyword(s):  
Microbial Community ◽  
Bacterial Community ◽  
Community Composition ◽  
Surface Sediment ◽  
Bohai Sea ◽  
Bacterial Community Composition ◽  
Influential Factor ◽  
Main Role ◽  
Composition Variation ◽  
Α Diversity

Abstract Background: Microbial spatial distribution has been widely investigated in sediment. However, there is poorly available information on microbial distribution patterns in sediment of Bohai Sea coastal zone. Results: Here, we investigated the bacterial community composition and diversity in riverine and marine surface sediment around and in the Bohai Sea using high-throughput sequencing. Bacterial communities mainly comprised Proteobacteria, Bacteroidetes, and Firmicutes. Salinity, dissolved oxygen, pH, and magnetic susceptibility played the main role in determining bacterial α-diversity and community composition in this region. Of the total bacterial community composition variation, environmental factors (explained 29.41% of the total microbial community composition variation) played a more important role than spatial variables (explained 3.03%) in conditioning the bacterial community composition. Meanwhile, the significantly pure spatial effect and distance-decay tendency suggested that dispersal limitation was also an influential factor in shaping the bacterial biogeographical pattern. The presence of magnetite center might shape the geographical distribution of five genera Lactococcus, Clostridium, Caulobacter, Gillisia and Sphingomonas probably by affecting their iron-related geochemical cycle.Conclusion: Our results may provide a better understanding of present-day bacterial biogeography and the correlation between microbial communities and key environmental variables in a typical coastal area. Depending on these information, coastal resources could be efficiently predicted, assessed and used.

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