Long-term agronomic practices alter the composition of asymbiotic diazotrophic bacterial community and their nitrogen fixation genes in an acidic red soil

2018 ◽  
Vol 54 (3) ◽  
pp. 329-339 ◽  
Author(s):  
Weibing Xun ◽  
Wei Li ◽  
Ting Huang ◽  
Yi Ren ◽  
Wu Xiong ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Bacterial Community ◽  
Red Soil ◽  
Agronomic Practices ◽  
Nitrogen Fixation Genes

scholarly journals Long-term warming effects on the microbiome and nitrogen fixation associated with the moss Racomitrium lanuginosum in Icelandic tundra

2019 ◽  
Author(s):  
Ingeborg J. Klarenberg ◽  
Christoph Keuschnig ◽  
Ana J. Russi Colmenares ◽  
Denis Warshan ◽  
Anne D. Jungblut ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Bacterial Community ◽  
Relative Abundance ◽  
Bacterial Communities ◽  
Bacterial Community Composition ◽  
The Arctic ◽  
Gene Copy ◽  
Nitrogen Fixing ◽  
Moss Species

AbstractBacterial communities form the basis of biogeochemical processes and determine plant growth and health. Mosses, an abundant plant group in Arctic ecosystems, harbour diverse bacterial communities that are involved in nitrogen fixation and carbon cycling. Global climate change is causing changes in aboveground plant biomass and shifting species composition in the Arctic, but little is known about the response of the moss microbiome. Here, we studied the total and potentially active bacterial community associated with Racomitrium lanuginosum, a common moss species in the Arctic, in response to 20-year in situ warming in an Icelandic heathland. We evaluated changes in moss bacterial community composition and diversity. Further, we assessed the consequences of warming for nifH gene copy numbers and nitrogen-fixation rates. Long-term warming significantly changed both the total and the potentially active bacterial community structure. The relative abundance of Proteobacteria increased, while the relative abundance of Cyanobacteria and Acidobacteria decreased. While warming did not affect nitrogen-fixation rates and nifH gene abundance, we did find shifts in the potentially nitrogen-fixing community, with Nostoc decreasing and non-cyanobacterial diazotrophs increasing in relative abundance. Our data suggests that the moss microbial community and the potentially nitrogen-fixing taxa are sensitive to future warming.

Soil remediation approach and bacterial community structure in a long-term contaminated soil by a mining spill (Aznalcóllar, Spain)

2021 ◽  
Vol 777 ◽  
pp. 145128
Author(s):  
M. Paniagua-López ◽  
M. Vela-Cano ◽  
D. Correa-Galeote ◽  
F. Martín-Peinado ◽  
F.J. Martínez Garzón ◽  
...  
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Soil Remediation ◽  
Contaminated Soil ◽  
Bacterial Community Structure

scholarly journals Impact of Diagnosed and Undiagnosed Respiratory Pseudomonas on VAP and VAE During Long-Term Acute Care

2020 ◽  
Vol 41 (S1) ◽  
pp. s258-s259
Author(s):  
James Harrigan ◽  
Ebbing Lautenbach ◽  
Emily Reesey ◽  
Magda Wernovsky ◽  
Pam Tolomeo ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Acute Care ◽  
Statistical Significance ◽  
Rrna Gene ◽  
Care Hospital ◽  
16S Sequencing ◽  
Increased Risk ◽  
Wide Range ◽  
The Impact

Background: Clinically diagnosed ventilator-associated pneumonia (VAP) is common in the long-term acute-care hospital (LTACH) setting and may contribute to adverse ventilator-associated events (VAEs). Pseudomonas aeruginosa is a common causative organism of VAP. We evaluated the impact of respiratory P. aeruginosa colonization and bacterial community dominance, both diagnosed and undiagnosed, on subsequent P. aeruginosa VAP and VAE events during long-term acute care. Methods: We enrolled 83 patients on LTACH admission for ventilator weaning, performed longitudinal sampling of endotracheal aspirates followed by 16S rRNA gene sequencing (Illumina HiSeq), and bacterial community profiling (QIIME2). Statistical analysis was performed with R and Stan; mixed-effects models were fit to relate the abundance of respiratory Psa on admission to clinically diagnosed VAP and VAE events. Results: Of the 83 patients included, 12 were diagnosed with P. aeruginosa pneumonia during the 14 days prior to LTACH admission (known P. aeruginosa), and 22 additional patients received anti–P. aeruginosa antibiotics within 48 hours of admission (suspected P. aeruginosa); 49 patients had no known or suspected P. aeruginosa (unknown P. aeruginosa). Among the known P. aeruginosa group, all 12 patients had P. aeruginosa detectable by 16S sequencing, with elevated admission P. aeruginosa proportional abundance (median, 0.97; IQR, 0.33–1). Among the suspected P. aeruginosa group, all 22 patients had P. aeruginosa detectable by 16S sequencing, with a wide range of admission P. aeruginosa proportional abundance (median, 0.0088; IQR, 0.00012–0.31). Of the 49 patients in the unknown group, 47 also had detectable respiratory Psa, and many had high P. aeruginosa proportional abundance at admission (median, 0.014; IQR, 0.00025–0.52). Incident P. aeruginosa VAP was observed within 30 days in 4 of the known P. aeruginosa patients (33.3%), 5 of the suspected P. aeruginosa patients (22.7%), and 8 of the unknown P. aeruginosa patients (16.3%). VAE was observed within 30 days in 1 of the known P. aeruginosa patients (8.3%), 2 of the suspected P. aeruginosa patients (9.1%), and 1 of the unknown P. aeruginosa patients (2%). Admission P. aeruginosa abundance was positively associated with VAP and VAE risk in all groups, but the association only achieved statistical significance in the unknown group (type S error <0.002 for 30-day VAP and <0.011 for 30-day VAE). Conclusions: We identified a high prevalence of unrecognized respiratory P. aeruginosa colonization among patients admitted to LTACH for weaning from mechanical ventilation. The admission P. aeruginosa proportional abundance was strongly associated with increased risk of incident P. aeruginosa VAP among these patients.Funding: NoneDisclosures: None

scholarly journals Long-term fate of nitrogen fixation in Pleurozium schreberi Brid (Mit.) moss carpets in boreal forests

2022 ◽  
Vol 169 ◽  
pp. 104215
Author(s):  
Thomas H. DeLuca ◽  
Olle Zackrisson ◽  
Marie-Charlotte Nilsson ◽  
Shouqin Sun ◽  
María Arróniz-Crespo
Keyword(s):  
Nitrogen Fixation ◽  
Boreal Forests ◽  
Pleurozium Schreberi ◽  
Fate Of Nitrogen

Expression of the nodulation and nitrogen fixation genes in Rhizobium meliloti during development

Genome ◽  
1989 ◽  
Vol 31 (1) ◽  
pp. 354-360 ◽  
Author(s):  
San Chiun Shen ◽  
Shui Ping Wang ◽  
Guan Qiao Yu ◽  
Jia Bi Zhu
Keyword(s):  
Nitrogen Fixation ◽  
Rhizobium Meliloti ◽  
Abnormal Development ◽  
Wild Type ◽  
Free Living ◽  
Nod Genes ◽  
Nodule Initiation ◽  
Fix Genes ◽  
Nitrogen Fixation Genes

Genes that specify nodulation (nod genes) are only active in the free-living rhizobia or in the nodule initiation state of rhizobia. As soon as the repression of nod genes occurs in the bacteroids of the nodule, nifA is induced, while ntrC is inactivated and thus the nifA-mediated nif/fix genes are turned on. Limitation of available oxygen brings about the induction of nifA, which reflects the actual status of nif/fix gene activities in symbiotic state of rhizobia. Oxygen thus appears to be a major symbiotic signal to the expression of bacteroid nif/fix genes. Mutation of nifA or shortage of nifA product in wild-type rhizobia caused by the inhibition of multicopy nifH/fixA promoters leads to an abnormal development of nodules and premature degradation of bacteroids in nodules.Key words: nitrogen fixation, nodulation, nif/fix regulation, nifA mutant.

Nitrification and acidification from urea application in red soil (Ferralic Cambisol) after different long-term fertilization treatments

2014 ◽  
Vol 14 (9) ◽  
pp. 1526-1536 ◽  
Author(s):  
Zejiang Cai ◽  
Boren Wang ◽  
Minggang Xu ◽  
Huimin Zhang ◽  
Lu Zhang ◽  
...  
Keyword(s):  
Red Soil

Bacterial Community Structure in a Mollisol Under Long-Term Natural Restoration, Cropping, and Bare Fallow History Estimated by PCR-DGGE

Pedosphere ◽  
2009 ◽  
Vol 19 (2) ◽  
pp. 156-165 ◽  
Author(s):  
Guang-Hua WANG ◽  
Jian JIN ◽  
Jun-Jie LIU ◽  
Xue-Li CHEN ◽  
Ju-Dong LIU ◽  
...  
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Bacterial Community Structure ◽  
Natural Restoration ◽  
Bare Fallow
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