Detoxification of mercury and organomercurials by nitrogen-fixing soil bacteria

1989 ◽  
Vol 14 (2) ◽  
pp. 173-182 ◽  
Author(s):  
S. Ray ◽  
R. Gachhui ◽  
K. Pahan ◽  
J. Chaudhury ◽  
A. Mandal
Keyword(s):  
Soil Bacteria ◽  
Nitrogen Fixing

scholarly journals How rhizobia adapt to the nodule environment

2021 ◽  
Author(s):  
Raphael Ledermann ◽  
Carolin C. M. Schulte ◽  
Philip S. Poole
Keyword(s):  
Nitrogen Fixation ◽  
Soil Bacteria ◽  
Root Nodule ◽  
Computational Modelling ◽  
Diverse Group ◽  
Nitrogen Fixing ◽  
The Core ◽  
Physiological Processes ◽  
Mutualistic Relationship ◽  
The Common

Rhizobia are a phylogenetically diverse group of soil bacteria that engage in mutualistic interactions with legume plants. Although specifics of the symbioses differ between strains and plants, all symbioses ultimately result in the formation of specialized root nodule organs which host the nitrogen-fixing microsymbionts called bacteroids. Inside nodules, bacteroids encounter unique conditions that necessitate global reprogramming of physiological processes and rerouting of their metabolism. Decades of research have addressed these questions using genetics, omics approaches, and more recently computational modelling. Here we discuss the common adaptations of rhizobia to the nodule environment that define the core principles of bacteroid functioning. All bacteroids are growth-arrested and perform energy-intensive nitrogen fixation fueled by plant-provided C4-dicarboxylates at nanomolar oxygen levels. At the same time, bacteroids are subject to host control and sanctioning that ultimately determine their fitness and have fundamental importance for the evolution of a stable mutualistic relationship.

scholarly journals From Intracellular Bacteria to Differentiated Bacteroids: Transcriptome and Metabolome Analysis inAeschynomeneNodules Using theBradyrhizobiumsp. Strain ORS285bclAMutant

2019 ◽  
Vol 201 (17) ◽  
Author(s):  
Florian Lamouche ◽  
Anaïs Chaumeret ◽  
Ibtissem Guefrachi ◽  
Quentin Barrière ◽  
Olivier Pierre ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcriptome Analysis ◽  
Soil Bacteria ◽  
Regulation Of Gene Expression ◽  
Nitrogen Fertilizers ◽  
Peptide Transporter ◽  
Intracellular Bacteria ◽  
Nitrogen Fixing ◽  
Wild Type ◽  
Free Living

ABSTRACTSoil bacteria called rhizobia trigger the formation of root nodules on legume plants. The rhizobia infect these symbiotic organs and adopt an intracellular lifestyle within the nodule cells, where they differentiate into nitrogen-fixing bacteroids. Several legume lineages force their symbionts into an extreme cellular differentiation, comprising cell enlargement and genome endoreduplication. The antimicrobial peptide transporter BclA is a major determinant of this process inBradyrhizobiumsp. strain ORS285, a symbiont ofAeschynomenespp. In the absence of BclA, the bacteria proceed until the intracellular infection of nodule cells, but they cannot differentiate into enlarged polyploid and functional bacteroids. Thus, thebclAnodule bacteria constitute an intermediate stage between the free-living soil bacteria and the nitrogen-fixing bacteroids. Metabolomics on whole nodules ofAeschynomene afrasperaandAeschynomene indicainfected with the wild type or thebclAmutant revealed 47 metabolites that differentially accumulated concomitantly with bacteroid differentiation. Bacterial transcriptome analysis of these nodules demonstrated that the intracellular settling of the rhizobia in the symbiotic nodule cells is accompanied by a first transcriptome switch involving several hundred upregulated and downregulated genes and a second switch accompanying the bacteroid differentiation, involving fewer genes but ones that are expressed to extremely elevated levels. The transcriptomes further suggested a dynamic role for oxygen and redox regulation of gene expression during nodule formation and a nonsymbiotic function of BclA. Together, our data uncover the metabolic and gene expression changes that accompany the transition from intracellular bacteria into differentiated nitrogen-fixing bacteroids.IMPORTANCELegume-rhizobium symbiosis is a major ecological process, fueling the biogeochemical nitrogen cycle with reduced nitrogen. It also represents a promising strategy to reduce the use of chemical nitrogen fertilizers in agriculture, thereby improving its sustainability. This interaction leads to the intracellular accommodation of rhizobia within plant cells of symbiotic organs, where they differentiate into nitrogen-fixing bacteroids. In specific legume clades, this differentiation process requires the bacterial transporter BclA to counteract antimicrobial peptides produced by the host. Transcriptome analysis ofBradyrhizobiumwild-type andbclAmutant bacteria in culture and in symbiosis withAeschynomenehost plants dissected the bacterial transcriptional response in distinct phases and highlighted functions of the transporter in the free-living stage of the bacterial life cycle.

scholarly journals Molecular Basis of Symbiotic Promiscuity

2000 ◽  
Vol 64 (1) ◽  
pp. 180-201 ◽  
Author(s):  
Xavier Perret ◽  
Christian Staehelin ◽  
William J. Broughton
Keyword(s):  
Host Range ◽  
Molecular Basis ◽  
Soil Bacteria ◽  
Molecular Mechanisms ◽  
Ecological Niches ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Nitrogen Input ◽  
Narrow Host Range

SUMMARY Eukaryotes often form symbioses with microorganisms. Among these, associations between plants and nitrogen-fixing bacteria are responsible for the nitrogen input into various ecological niches. Plants of many different families have evolved the capacity to develop root or stem nodules with diverse genera of soil bacteria. Of these, symbioses between legumes and rhizobia (Azorhizobium, Bradyrhizobium, Mesorhizobium, and Rhizobium) are the most important from an agricultural perspective. Nitrogen-fixing nodules arise when symbiotic rhizobia penetrate their hosts in a strictly controlled and coordinated manner. Molecular codes are exchanged between the symbionts in the rhizosphere to select compatible rhizobia from pathogens. Entry into the plant is restricted to bacteria that have the “keys” to a succession of legume “doors”. Some symbionts intimately associate with many different partners (and are thus promiscuous), while others are more selective and have a narrow host range. For historical reasons, narrow host range has been more intensively investigated than promiscuity. In our view, this has given a false impression of specificity in legume-Rhizobium associations. Rather, we suggest that restricted host ranges are limited to specific niches and represent specialization of widespread and more ancestral promiscuous symbioses. Here we analyze the molecular mechanisms governing symbiotic promiscuity in rhizobia and show that it is controlled by a number of molecular keys.

Nitrogen-Fixing Soil Bacteria Plus Mycorrhizal Fungi Improve Seed Yield and Quality Traits of Lentil (Lens culinaris Medik)

2019 ◽  
Vol 19 (3) ◽  
pp. 592-602 ◽  
Author(s):  
Reza Amirnia ◽  
Mahdi Ghiyasi ◽  
Sina Siavash Moghaddam ◽  
Amir Rahimi ◽  
Christos A. Damalas ◽  
...  
Keyword(s):  
Seed Yield ◽  
Mycorrhizal Fungi ◽  
Soil Bacteria ◽  
Lens Culinaris ◽  
Quality Traits ◽  
Nitrogen Fixing ◽  
Yield And Quality

scholarly journals Mercury resistance in nitrogen-fixing soil bacteria.

1989 ◽  
Vol 35 (2) ◽  
pp. 83-94 ◽  
Author(s):  
SATYAJIT RAY ◽  
RATAN GACHHUI ◽  
JAYASRI CHAUDHURI ◽  
A. MANDAL
Keyword(s):  
Soil Bacteria ◽  
Mercury Resistance ◽  
Nitrogen Fixing

scholarly journals Larger plants promote a greater diversity of symbiotic nitrogen-fixing soil bacteria associated with an Australian endemic legume

2018 ◽  
Vol 107 (2) ◽  
pp. 977-991 ◽  
Author(s):  
Russell Dinnage ◽  
Anna K. Simonsen ◽  
Luke G. Barrett ◽  
Marcel Cardillo ◽  
Nat Raisbeck-Brown ◽  
...  
Keyword(s):  
Soil Bacteria ◽  
Nitrogen Fixing

Metallophore profiling of nitrogen-fixingFrankiaspp. to understand metal management in the rhizosphere of actinorhizal plants

Metallomics ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 810-821 ◽  
Author(s):  
Michael Deicke ◽  
Jan Frieder Mohr ◽  
Sébastien Roy ◽  
Peter Herzsprung ◽  
Jean-Philippe Bellenger ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Soil Bacteria ◽  
Actinorhizal Plants ◽  
Nitrogen Fixing

Frankiaspp. are widespread nitrogen-fixing and metallophore releasing soil bacteria, which often live in symbiosis with a broad spectrum of hosts.

scholarly journals The importance of Rhizobium, Agrobacterium, Bradyrhizobium, Herbaspirillum, Sinorhizobium in sustainable agricultural production

2021 ◽  
Vol 49 (3) ◽  
pp. 12183
Author(s):  
Mohamad H. SHAHRAJABIAN ◽  
Wenli SUN ◽  
Qi CHENG
Keyword(s):  
Nitrogen Fixation ◽  
Cell Division ◽  
Nitrogen Content ◽  
Root Hair ◽  
Agricultural Production ◽  
Soil Bacteria ◽  
Organic Nitrogen ◽  
Nitrogen Fixing ◽  
Review Of The Literature ◽  
Nod Factor

Rhizobia which are soil bacteria capable of symbiosis with legume plants in the root or stem nodules and perform nitrogen fixation. Rhizobial genera include Agrobacterium, Allorhizobium, Aminobacter, Azorhizobium, Bradyrhizobium, Devosia, Mesorhizobium, Methylobacterium, Microvirga, Ochrobacterum, Phyllobacterium, Rhizobium, Shinella and Ensifer (Sinorhizobium). Review of the literature was carried out using the keywords Rhizobium, Agrobacterium, Bradyrhizobium, Herbaspirillum and Sinorhizobium. Rhizobial nodulation symbioses steps are included flavonoid signaling, Nod factor induction, and Nod factor perception, root hair responses, rhizobial infection, cell division and formation of nitrogen-fixing nodule. Rhizobium improves sustainable production by boosting organic nitrogen content.

Nitrogen-fixing trees

AccessScience ◽  
2015 ◽  
Keyword(s):  
Nitrogen Fixing ◽  
Nitrogen Fixing Trees

Environmental effects on the growth of nitrogen-fixing bacteria

1972 ◽  
Vol 22 (4) ◽  
pp. 541-558 ◽  
Author(s):  
Susan Hill ◽  
J. W. Drozd ◽  
J. R. Postgate
Keyword(s):  
Environmental Effects ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria
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