scholarly journals Effect of Predation by Colpoda sp. in Nitrogen Fixation Rate of Two Free-Living Bacteria

2021 ◽  
Author(s):  
Carlos Manuel Martínez-Reyes ◽  
Salvador Rodríguez Zaragoza ◽  
Nathalie Cabirol ◽  
Alejandro Alarcón ◽  
Ma. Remedios Mendoza-López
Keyword(s):  
Nitrogen Fixation ◽  
Soil Microbial Communities ◽  
Bacterial Biomass ◽  
Lag Phase ◽  
Biological Fixation ◽  
Free Living ◽  
Fixation Rate ◽  
Soil Microbial ◽  
Significant Difference ◽  
Predation Effect

Abstract Biological nitrogen fixation (BNF) is limited to several groups of prokaryotes, which can reduce nitrogen through complex endosymbiotic relationships or as free-living nitrogen-fixing bacteria (FLNFB). Predation of FLNFB by protozoa releases reduced nitrogen, enhancing the formation of plant and bacterial biomass as well as nitrogen (N) mineralization within soil microbial communities. We aim to evaluate the predation effect of Colpoda sp. on two FLNFB Azospirillum lipoferum and Stenotrophomonas sp. during their exponential and lag phase. The likelihood of Colpoda sp. to feed on the former species was needed to ensure there is a predation effect. The kinetics of bacterial population growth was determined in the predators’ presence or absence and the effect of predation on the biological fixation of N was evaluated through the reduction of acetylene to ethylene technique. Colpoda sp. showed a non-significant difference in preferences between the two species offered as prey. Consequently, the abundance of A. lipoferum and Stenotrophomonas sp. decreased significantly due to predator’s pressure. However, it had a higher positive effect on the formation of new bacterial biomass on Stenotrophomonas sp.as revealed by the increase of its specific growth rate. Likewise, predation promoted greater nitrogen fixation in A. lipoferum and Stenotrophomonas sp. during the lag phase (0.34 nM and 0.38 nM) than in the exponential phase (0.27 nM and 0.17 nM). We concluded that predation by Colpodasp stimulates the rate of nitrogen fixation of A. lipoferum and Stenotrophomonas sp.

Native bacteria and cyanobacteria consortia improve seedling emergence and establishment in dryland restoration

2021 ◽  
Author(s):  
Frederick Dadzie ◽  
Angela Moles ◽  
Todd Erickson ◽  
Miriam Munoz-Rojas
Keyword(s):  
Soil Bacteria ◽  
Donor Site ◽  
Seedling Emergence ◽  
Soil Microbial Communities ◽  
Degraded Land ◽  
North West ◽  
Soil Microbial ◽  
Rehabilitation Programs ◽  
Significant Difference ◽  
Seedling Emergence And Survival

<p>Seed-based ecosystem restoration has huge potential to restore degraded lands but currently less than 10 % of directly sown seeds successfully establish in drylands. Soil microbial communities are important for improving plant establishment in degraded land. However, current methods such as soil translocation can potentially disturb the donor site. In this study, we investigated a novel non-destructive method for improving seedling growth of native plants used in restoration through seed-soil-microbial pelleting. We assessed seedling emergence and survival of <em>Triodia epactia</em> and <em>Acacia inaequilatera</em> seeds inoculated with whole soil bacteria and cyanobacteria consortia retrieved and isolated from a pristine ecosystem. A field experiment was set-up in a 35m x 40m purpose-built rain exclusion shelter that contained reconstructed soil profiles typically encountered in mine rehabilitation programs of Australia’s arid north-west. We hypothesized that inoculated seed-soil pellets would improve seedling emergence and survival of these species. After three weeks of planting, seedling emergence in microbially inoculated <em>Acacia</em> <em>inaequilatera</em> and <em>Triodia epactia</em> were 48% and 55% higher than non-inoculated seeds in bacteria and cyanobacteria, respectively. We also tested whether the use of cyanobacteria consortia as inocula promoted higher seedling emergence over whole soil bacteria. We found that there was no significant difference in seedling emergence between the microbial taxa. We show that, improving the diversity of soil microorganisms improves seedling emergence and the seed-soil pellet method used is viable to improve seed-based restoration outcomes.</p><p><strong>Key words</strong>: Seed-based restoration, microbial community, cyanobacteria, bacteria community, seedling emergence.</p>

scholarly journals Bacterial and fungal communities experience rapid succession during the first year following a wildfire in a California chaparral.

2021 ◽  
Author(s):  
M. Fabiola Pulido-Chavez ◽  
James W. J. Randolph ◽  
Cassandra Zalman ◽  
Loralee Larios ◽  
Peter M. Homyak ◽  
...  
Keyword(s):  
Fungal Biomass ◽  
Secondary Succession ◽  
Soil Microbial Communities ◽  
Bacterial Biomass ◽  
Illumina Miseq ◽  
High Temporal Resolution ◽  
Rapid Succession ◽  
Time Points ◽  
Soil Microbial ◽  
Successional Stages

The rise in wildfire frequency in the western United States has increased interest in secondary succession. However, despite the role of soil microbial communities in plant regeneration and establishment, microbial secondary succession is poorly understood owing to a lack of measurements immediately post-fire and at high temporal resolution. To fill this knowledge gap, we collected soils at 2 and 3 weeks and 1, 2, 3, 4, 6, 9, and 12 months after a chaparral wildfire in Southern California. We assessed bacterial and fungal biomass with qPCR of 16S and 18S and richness and composition with Illumina MiSeq sequencing of the 16S and ITS2 amplicons. We found that fire severely reduced bacterial biomass by 47% and richness by 46%, but the impacts were stronger for fungi, with biomass decreasing by 86% and richness by 68%. These declines persisted for the entire post-fire year, but bacterial biomass and richness oscillated in response to precipitation, whereas fungal biomass and richness did not. Fungi and bacteria experienced rapid succession, with 5-6 compositional turnover periods. As with plants, fast-growing surviving microbes drove successional dynamics. For bacteria, succession was driven by the phyla Firmicutes and Proteobacteria, with the Proteobacteria Massilia dominating all successional time points, and the Firmicutes (Domibacillus and Paenibacillus) dominating early- to mid-successional stages (1-4.5 months), while the Proteobacteria Noviherbaspirillum dominated late successional stages (4.5-1 year). For fungi, succession was driven by the phyla Ascomycota, but ectomycorrhizal basidiomycetes, and the heat-resistant yeast, Geminibasidium were present in the early successional stages (1 month). However, pyrophilous filamentous Ascomycetes Pyronema, Penicillium, and Aspergillus, dominated all post-fire time points. While wildfires vastly decrease bacterial and fungal biomass and richness, similar to plants, pyrophilous bacteria and fungi increase in abundance and experience rapid succession and compositional turnover in the first post-fire year, with potential implications for post-fire chaparral regeneration

The invasive potential of a hybrid species: insights from soil chemical properties and soil microbial communities

2019 ◽  
Vol 13 (1) ◽  
pp. 20-26
Author(s):  
Feng Sun ◽  
Yuyi Ou ◽  
Qiaojing Ou ◽  
Lingda Zeng ◽  
Hanxia Yu ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Photosynthetic Rate ◽  
Soil Microbial Communities ◽  
Chemical Properties ◽  
Soil Chemical Properties ◽  
Natural Hybridization ◽  
Total Biomass ◽  
Invasive Potential ◽  
Soil Microbial ◽  
Significant Difference

Abstract Aims Natural hybridization between invasive and native species, as a form of adaptive evolution, threatens biodiversity worldwide. However, the potential invasive mechanisms of hybrids remain essentially unexplored, especially insights from soil chemical properties and soil microbial communities. Methods In a field experiment, soil microbial community, potassium-solubilizing bacteria, phosphorus-solubilizing bacteria, enzyme activities, and light-saturated photosynthetic rate were measured in invasive Sphagneticola trilobata and its hybrid with native Sphagneticola calendulacea in 2 years. Important Findings In general, soil dissolved organic carbon and the biomass of phosphorus-solubilizing bacteria were significantly higher under the hybrid treatment than S. trilobata and S. calendulacea. However, there were no significant differences in acid phosphatase, total PLFAs, bacterial PLFAs, fungi PLFAs, cellulase, and urase in these treatments. The hybrids had significantly higher light-saturated photosynthetic rate, photosynthetic nitrogen-, phosphorus-, potassium- use efficiencies than the invasive S. trilobata, but no significant difference with S. calendulacea. The total biomass and root biomass of hybrids were higher than S. calendulacea. Our results indicate that the hybrids species have a higher invasive potential than S. calendulacea, which may aggravate the local extinction of S. calendulacea in the future.

scholarly journals Effect of Predation by Colpoda sp. in Nitrogen Fixation Rate of Two Free-Living Bacteria

2021 ◽  
Author(s):  
Carlos Manuel Martínez-Reyes ◽  
Salvador Rodríguez-Zaragoza ◽  
Nathalie Cabirol ◽  
Alejandro Alarcón ◽  
Ma. Remedios Mendoza-López
Keyword(s):  
Nitrogen Fixation ◽  
Free Living ◽  
Fixation Rate ◽  
Living Bacteria

scholarly journals Impact of Fumigants on Soil Microbial Communities

2001 ◽  
Vol 67 (7) ◽  
pp. 3245-3257 ◽  
Author(s):  
A. Mark Ibekwe ◽  
Sharon K. Papiernik ◽  
Jianying Gan ◽  
Scott R. Yates ◽  
Ching-Hong Yang ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Phospholipid Fatty Acid ◽  
Soil Microbial Communities ◽  
Bacterial Biomass ◽  
Effective Control ◽  
Soil Microbial Community Structure ◽  
Soil Dna ◽  
Soil Microbial ◽  
Plfa Analysis

ABSTRACT Agricultural soils are typically fumigated to provide effective control of nematodes, soilborne pathogens, and weeds in preparation for planting of high-value cash crops. The ability of soil microbial communities to recover after treatment with fumigants was examined using culture-dependent (Biolog) and culture-independent (phospholipid fatty acid [PLFA] analysis and denaturing gradient gel electrophoresis [DGGE] of 16S ribosomal DNA [rDNA] fragments amplified directly from soil DNA) approaches. Changes in soil microbial community structure were examined in a microcosm experiment following the application of methyl bromide (MeBr), methyl isothiocyanate, 1,3-dichloropropene (1,3-D), and chloropicrin. Variations among Biolog fingerprints showed that the effect of MeBr on heterotrophic microbial activities was most severe in the first week and that thereafter the effects of MeBr and the other fumigants were expressed at much lower levels. The results of PLFA analysis demonstrated a community shift in all treatments to a community dominated by gram-positive bacterial biomass. Different 16S rDNA profiles from fumigated soils were quantified by analyzing the DGGE band patterns. The Shannon-Weaver index of diversity,H, was calculated for each fumigated soil sample. High diversity indices were maintained between the control soil and the fumigant-treated soils, except for MeBr (H decreased from 1.14 to 0.13). After 12 weeks of incubation, Hincreased to 0.73 in the MeBr-treated samples. Sequence analysis of clones generated from unique bands showed the presence of taxonomically unique clones that had emerged from the MeBr-treated samples and were dominated by clones closely related to Bacillus spp. andHeliothrix oregonensis. Variations in the data were much higher in the Biolog assay than in the PLFA and DGGE assays, suggesting a high sensitivity of PLFA analysis and DGGE in monitoring the effects of fumigants on soil community composition and structure. Our results indicate that MeBr has the greatest impact on soil microbial communities and that 1,3-D has the least impact.

scholarly journals Soil Microbial Communities Altered by Titanium Ions in Different Agroecosystems of Pitaya and Grape

2021 ◽  
Author(s):  
Yuan He ◽  
Xinrong Ma ◽  
Xin-Yi Hou ◽  
Cai-Xia Li ◽  
Yan Wang
Keyword(s):  
Microbial Community ◽  
Microbial Communities ◽  
Soil Microbial Community ◽  
Soil Microbial Communities ◽  
Foliar Spray ◽  
Rrna Gene ◽  
Soil Microbial Diversity ◽  
Soil Microbiota ◽  
Soil Microbial ◽  
Significant Difference

Abstract Titanium ions can significantly promote plant growth, but it is unclear whether the application of titanium ions to plants has any effect on the soil microbial community. In this study, we conducted field surveys to determine the effect of titanium ions on soil microbial communities of the pitaya and grape plantations in Panxi area by performing full-length 16S rRNA gene and ITS amplicon sequencing using PacBio Sequel. The results showed that the application of titanium ions significantly altered the composition and structure of soil microbiota. Root irrigation with titanium ions in pitaya garden, the diversity of soil fungi was significantly reduced. Although there was no statistically significant difference, bacterial diversity also declined. While, the foliar spray of titanium ions on grapes greatly reduced the soil microbial diversity. Moreover, the soil microbiota had a core of conserved taxa, and their relative abundances were significantly altered by titanium ions. Moreover, titanium ions enhanced the cooccurrence relationships and probably improved the stability of the soil microbial community. Our results highlight the different responses of bacterial and fungal communities to titanium ions and sites and provides a basis for the application of titanium ions in plant farming.

scholarly journals Land conversion changes soil microbial community structure and diversity

2020 ◽  
Author(s):  
Tong Zhang ◽  
Yufei Liu ◽  
Xin Sui ◽  
Fuqiang Song
Keyword(s):  
Land Use ◽  
Community Structure ◽  
Microbial Communities ◽  
Soil Microbial Communities ◽  
Community Diversity ◽  
Forest Land ◽  
Soil Microbial Community Structure ◽  
Soil Microbial ◽  
Significant Difference ◽  
The Impact

Abstract Background: To study the impact of land-use change on soil microbial community structure and diversity in Northeast China, three typical land-use types (plough, grassland, and forest), from grassland change to forest land and grassland change to plough, in the Qiqihar region of Heilongjiang Province were taken as research objects. Methods: MiSeq high-throughput sequencing technology based on bacterial 16S rRNA and fungal ITS rRNA was used to study the above community structure of soil bacteria and fungi and to explore the relationship between soil bacteria and soil environmental factors. Results: The results showed that there was no significant difference in soil bacterial community diversity and fungal community diversity after the grassland was completely changed to forest land. The dominant bacterial phylum changed from Actinobacteria to Acidobacteria, the dominant fungal phylum changed from Ascomycetes to Basidiomycetes, and the ECM functional group increased significantly. After the grassland was changed to plough, there was no significant difference in the diversity of soil bacterial communities, and the diversity of fungal communities increased significantly. The dominant phylum changed from Actinomycetes to Proteobacteria. The dominant phylum was still Ascomycetes, and the functional groups of pathogens and parasites increased significantly. CCA showed that soil pH, MC, NO3--N, TP and AP were important factors affecting the composition of soil microbial communities, and changes in land-use patterns changed the physical and chemical properties of soils, thereby affecting the structure and diversity of microbial communities. Conclusions: Our research results clarify the impact of changes in land use on the characteristics of soil microbial communities and provide basic data on the healthy use of land.

scholarly journals Responses of soil microbial communities to freeze–thaw cycles in a Chinese temperate forest

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Changpeng Sang ◽  
Zongwei Xia ◽  
Lifei Sun ◽  
Hao Sun ◽  
Ping Jiang ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Microbial Communities ◽  
Community Composition ◽  
Temperate Forest ◽  
Soil Microbial Communities ◽  
Bacterial Biomass ◽  
Community Diversity ◽  
Freeze Thaw ◽  
Soil Microbial ◽  
C And N

Abstract Background Freeze–thaw events are common in boreal and temperate forest ecosystems and are increasingly influenced by climate warming. Soil microorganisms play an important role in maintaining ecosystem stability, but their responses to freeze–thaw cycles (FTCs) are poorly understood. We conducted a field freeze–thaw experiment in a natural Korean pine and broadleaf mixed forest in the Changbai Mountain Nature Reserve, China, to determine the dynamic responses of soil microbial communities to FTCs. Results Bacteria were more sensitive than fungi to FTCs. Fungal biomass, diversity and community composition were not significantly affected by freeze–thaw regardless of the stage. Moderate initial freeze–thaw resulted in increased bacterial biomass, diversity, and copiotrophic taxa abundance. Subsequent FTCs reduced the bacterial biomass and diversity. Compared with the initial FTC, subsequent FTCs exerted an opposite effect on the direction of change in the composition and function of the bacterial community. Soil water content, dissolved organic carbon, ammonium nitrogen, and total dissolved phosphorus were important factors determining bacterial community diversity and composition during FTCs. Moreover, the functional potentials of the microbial community involved in C and N cycling were also affected by FTCs. Conclusions Different stages of FTCs have different ecological effects on the soil environment and microbial activities. Soil FTCs changed the soil nutrients and water availability and then mainly influenced bacterial community composition, diversity, and functional potentials, which may disturb C and N states in this temperate forest soil. This study also improves our understanding of microbial communities regulating their ecological functions in response to climate change.

Novel aspects of nitrogen fixation

1977 ◽  
Vol 9 (4) ◽  
pp. 180-185 ◽  
Author(s):  
J M Day ◽  
J F Witty
Keyword(s):  
Nitrogen Fixation ◽  
Green Algae ◽  
Root Nodule ◽  
Atmospheric Nitrogen ◽  
Biological Fixation ◽  
Free Living ◽  
Tropical Grasses ◽  
Blue Green Algae ◽  
Synthetic Fertilizers ◽  
Living Bacteria

Only a fraction of the total agricultural need for nitrogen comes from natural or synthetic fertilizers. The remainder is satisfied largely through the biological fixation of atmospheric nitrogen. Whilst this is most efficiently effected by the Rhizobium-legume root nodule, free-living bacteria and blue-green algae are known to be capable of fixing appreciable amounts. Recently, attention has been focused on bacteria closely associated with roots of certain tropical grasses.

scholarly journals Metagenomic Insights into Rhizospheric Microbiome Profiling in Lentil Cultivars Unveils Differential Microbial Nitrogen and Phosphorus Metabolism under Rice-Fallow Ecology

2020 ◽  
Vol 21 (23) ◽  
pp. 8895
Author(s):  
Krishnendu Pramanik ◽  
Arpita Das ◽  
Joydeep Banerjee ◽  
Anupam Das ◽  
Shayree Chatterjee ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Soil Microbial Communities ◽  
Foraging Strategy ◽  
Taxonomic Structure ◽  
N Fixation ◽  
Nitrogen And Phosphorus ◽  
Microbiome Composition ◽  
Soil Microbial ◽  
P Cycling ◽  
Significant Difference

The plant rhizosphere interfaces an array of microbiomes related to plant growth and development. Cultivar-specific soil microbial communities with respect to their taxonomic structure and specific function have not been investigated explicitly in improving the adaptation of lentil cultivars under rice-fallow ecology. The present study was carried out to decipher the rhizosphere microbiome assembly of two lentil cultivars under rice-fallow ecology for discerning the diversity of microbial communities and for predicting the function of microbiome genes related to nitrogen (N) and phosphorus (P) cycling processes deploying high-throughput whole (meta) genome sequencing. The metagenome profile of two cultivars detected variable microbiome composition with discrete metabolic activity. Cyanobacteria, Bacteroidetes, Proteobacteria, Gemmatimonadetes, and Thaumarchaeota were abundant phyla in the “Farmer-2” rhizosphere, whereas Actinobacteria, Acidobacteria, Firmicutes, Planctomycetes, Chloroflexi, and some incompletely described procaryotes of the “Candidatus” category were found to be robustly enriched the rhizosphere of “Moitree”. Functional prediction profiles of the microbial metagenomes between two cultivars revealed mostly house keeping genes with general metabolism. Additionally, the rhizosphere of “Moitree” had a high abundance of genes related to denitrification processes. Significant difference was observed regarding P cycling genes between the cultivars. “Moitree” with a profuse root system exhibited better N fixation and translocation ability due to a good “foraging strategy” for improving acquisition of native P under the nutrient depleted rice-fallow ecology. However, “Farmer-2” revealed a better “mining strategy” for enhancing P solubilization and further transportation to sinks. This study warrants comprehensive research for explaining the role of microbiome diversity and cultivar–microbe interactions towards stimulating microbiome-derived soil reactions regarding nutrient availability under rice-fallow ecology.

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