Abstract Soil microbial respiration is an important source of uncertainty in projecting future climate and carbon (C) cycle feedbacks. However, its feedbacks to climate warming and underlying ...microbial mechanisms are still poorly understood. Here we show that the temperature sensitivity of soil microbial respiration (Q10) in a temperate grassland ecosystem persistently decreases by 12.0 ± 3.7% across 7 years of warming. Also, the shifts of microbial communities play critical roles in regulating thermal adaptation of soil respiration. Incorporating microbial functional gene abundance data into a microbially-enabled ecosystem model significantly improves the modeling performance of soil microbial respiration by 5–19%, and reduces model parametric uncertainty by 55–71%. In addition, modeling analyses show that the microbial thermal adaptation can lead to considerably less heterotrophic respiration (11.6 ± 7.5%), and hence less soil C loss. If such microbially mediated dampening effects occur generally across different spatial and temporal scales, the potential positive feedback of soil microbial respiration in response to climate warming may be less than previously predicted.
Biofuel-cropping systems, projected for large land areas, can potentially change their soil microbiome and the ecosystem services they catalyze. Here, we determined the bacterial community ...composition and relevant soil properties for samples collected after 6 crop years at 0–10 cm, 10–25 cm, 25–50 cm, and 50–100 cm under corn, switchgrass, Miscanthus, and restored prairie, as well as 0–10 cm under six additional candidate biofuel crops in replicate side-by side plots. Deep sequencing of the 16S rRNA-V4 region established that soil bacterial communities were significantly differentiated by depth as determined by proportional OTU abundance and composition, UniFrac distance, and taxonomic and indicator analyses. The cropping system significantly impacted bacterial community composition within the top three layers, with corn and switchgrass communities the most different within the 0–25 cm and 25–50 cm depths, respectively. The effects of crop type and depth co-mingled, likely attributed to differences in rooting depth and biomass among crops. Individual phyla demonstrated varying patterns with depth, with significant proportional decreases of Proteobacteria, Actinobacteria, Planctomycetes, and Bacteroidetes but proportional increases of Firmicutes from shallow to deep soils. The Acidobacteria, Verrucomicrobia, and Chloroflexi peaked in abundance in the middle layers, whereas Thaumarchaeota decreased in abundance. Importantly, some classes within the Acidobacteria, Verrucomicrobia, and Firmicutes followed contrasting patterns with depth suggesting that they have different ecological specializations. Poplar, followed by soils with perennial crops contained the most C in the surface soils, with data indicating that these differences will become more pronounced with time.
Increases in carbon (C) inputs to soil can replenish soil organic C (SOC) through various mechanisms. However, recent studies have suggested that the increased C input can also stimulate the ...decomposition of old SOC via priming. Whether the loss of old SOC by priming can override C replenishment has not been rigorously examined. Here we show, through data–model synthesis, that the magnitude of replenishment is greater than that of priming, resulting in a net increase in SOC by a mean of 32% of the added new C. The magnitude of the net increase in SOC is positively correlated with the nitrogen-to-C ratio of the added substrates. Additionally, model evaluation indicates that a two-pool interactive model is a parsimonious model to represent the SOC decomposition with priming and replenishment. Lastly, our findings suggest that increasing C input to soils likely promote SOC accumulation despite the enhanced decomposition of old C via priming.
Panama disease caused by
Fusarium oxysporum
f. sp.
cubense
infection on banana is devastating banana plantations worldwide. Biological control has been proposed to suppress Panama disease, though the ...stability and survival of bio-control microorganisms in field setting is largely unknown. In order to develop a bio-control strategy for this disease, 16S rRNA gene sequencing was used to assess the microbial community of a disease-suppressive soil.
Bacillus
was identified as the dominant bacterial group in the suppressive soil. For this reason,
B. amyloliquefaciens
NJN-6 isolated from the suppressive soil was selected as a potential bio-control agent. A bioorganic fertilizer (BIO), formulated by combining this isolate with compost, was applied in nursery pots to assess the bio-control of Panama disease. Results showed that BIO significantly decreased disease incidence by 68.5%, resulting in a doubled yield. Moreover, bacterial community structure was significantly correlated to disease incidence and yield and
Bacillus
colonization was negatively correlated with pathogen abundance and disease incidence, but positively correlated to yield. In total, the application of BIO altered the rhizo-bacterial community by establishing beneficial strains that dominated the microbial community and decreased pathogen colonization in the banana rhizosphere, which plays an important role in the management of Panama disease.
Natural biological suppression of soil-borne diseases is a function of the activity and composition of soil microbial communities. Soil microbe and phytopathogen interactions can occur prior to crop ...sowing and/or in the rhizosphere, subsequently influencing both plant growth and productivity. Research on suppressive microbial communities has concentrated on bacteria although fungi can also influence soil-borne disease. Fungi were analyzed in co-located soils 'suppressive' or 'non-suppressive' for disease caused by Rhizoctonia solani AG 8 at two sites in South Australia using 454 pyrosequencing targeting the fungal 28S LSU rRNA gene. DNA was extracted from a minimum of 125 g of soil per replicate to reduce the micro-scale community variability, and from soil samples taken at sowing and from the rhizosphere at 7 weeks to cover the peak Rhizoctonia infection period. A total of ~994,000 reads were classified into 917 genera covering 54% of the RDP Fungal Classifier database, a high diversity for an alkaline, low organic matter soil. Statistical analyses and community ordinations revealed significant differences in fungal community composition between suppressive and non-suppressive soil and between soil type/location. The majority of differences associated with suppressive soils were attributed to less than 40 genera including a number of endophytic species with plant pathogen suppression potentials and mycoparasites such as Xylaria spp. Non-suppressive soils were dominated by Alternaria, Gibberella and Penicillum. Pyrosequencing generated a detailed description of fungal community structure and identified candidate taxa that may influence pathogen-plant interactions in stable disease suppression.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Anaerobic ammonium oxidation (anammox) is a recently discovered nitrogen removal pathway in natural systems. First found to be a significant nitrogen sink in the Black Sea anoxic water column in ...2003, anammox has shown to be responsible for as much as 79% of N2 production in marine sediments. Little is known concerning the significance of anammox in freshwater systems and even less information is available about this pathway in terrestrial systems. Evidence shows that anammox is active in sea ice and the bacteria responsible have been identified in Siberian permafrost. A slow metabolic rate coupled with significant activity in cold deep sea sediments suggests that these bacteria may contribute to nitrogen removal in permafrost soils.
In the original published version of the article, Valerie Vancollie was mistakenly omitted from the list of members of the International Mouse Phenotyping Consortium. In addition, recognition of ...funding from Wellcome Trust grant WT098051 was mistakenly omitted from the Acknowledgements.The errors have been corrected in both the PDF and HTML versions of the paper.
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