A5052235417- Legume Nitrogen Fixing Symbiosis
- Bacterial Genetics and Biotechnology
- Protist diversity and phylogeny
- Photosynthetic Processes and Mechanisms
- Plant-Microbe Interactions and Immunity
- Microbial Community Ecology and Physiology
- Genomics and Phylogenetic Studies
- Bacterial biofilms and quorum sensing
- Photoreceptor and optogenetics research
- Micro and Nano Robotics
- Enzyme-mediated dye degradation
- Mycorrhizal Fungi and Plant Interactions
- Nematode management and characterization studies
- Vibrio bacteria research studies
- Plant nutrient uptake and metabolism
- Microbial Fuel Cells and Bioremediation
- Enzyme Structure and Function
- Bacteriophages and microbial interactions
- Plant Parasitism and Resistance
- Plant Pathogenic Bacteria Studies
- Cell Image Analysis Techniques
- Slime Mold and Myxomycetes Research
- Plant tissue culture and regeneration
- Plant Stress Responses and Tolerance
- Digital Holography and Microscopy
University of Tennessee at Knoxville
2016-2025
Oak Ridge National Laboratory
2010-2011
Georgia State University
2003-2009
Loma Linda University
1999-2004
Georgia Institute of Technology
2001-2003
Centre National de la Recherche Scientifique
1997-1999
Université Claude Bernard Lyon 1
1996-1999
Ecologie Microbienne Lyon
1998
Fossil records indicate that life appeared in marine environments ∼3.5 billion years ago (Gyr) and transitioned to terrestrial ecosystems nearly 2.5 Gyr. Sequence analysis suggests "hydrobacteria" "terrabacteria" might have diverged as early 3 Bacteria of the genus Azospirillum are associated with roots plants; however, virtually all their close relatives aquatic. We obtained genome sequences two species analyzed gene origins. While most house-keeping genes orthologs its aquatic relatives,...
Abstract Background While being a standard powerful molecular biology technique, applications of the PCR to amplification high GC-rich DNA samples still present challenges which include limited yield and poor specificity reaction. Organic solvents, including DMSO formamide, have been often employed as additives increase efficiency GC content (GC > 60%) sequences. Bovine serum albumin (BSA) has used an additive in several applications, restriction enzyme digestions well templates from...
Rhizobium leguminosarum biovar viciae strain 3841 is a motile alpha-proteobacterium that can establish nitrogen-fixing symbiosis within the roots of pea plants. In order to determine contribution chemotaxis lifestyle R. leguminosarum, we have characterized function two gene clusters (che1 and che2) in controlling motility behaviour. We found both modulate swimming bias cells che1 cluster major pathway chemotaxis. The che2 also contributes bias, but has minor effect on Using competitive...
Although the influence of microbiomes on health plant hosts is evident, specific mechanisms shaping structure and dynamics microbial communities in phyllosphere rhizosphere are only beginning to become clear. Traditionally, plant–microbe interactions have been studied using cultured isolates but rising use ‘omics tools provides novel snapshots total complex community situ. Here, we discuss recent advances techniques used monitor chemical signals that these relationships above- belowground...
Energy taxis encompasses aerotaxis, phototaxis, redox taxis, to alternative electron acceptors, and chemotaxis oxidizable substrates. The signal for this type of behavior is originated within the transport system. was demonstrated, as a part an overall behavior, in several microbial species, but it did not appear dominant determinant any them. In study, we show that most behavioral responses proceed through mechanism alpha-proteobacterium Azospirillum brasilense. First, chemoeffectors...
A chemotaxis signal transduction pathway (hereafter called Che1) has been previously identified in the alphaproteobacterium Azospirillum brasilense. Previous experiments have demonstrated that although mutants lacking CheB and/or CheR homologs from this are defective chemotaxis, a mutant which entire mutated displayed phenotype mostly similar to of parent strain, suggesting primary function Che1 is not control motility behavior. Here, we report carrying defined mutations cheA1 (strain AB101)...
Chemoreceptors provide sensory specificity and sensitivity that enable motile bacteria to seek optimal positions for growth metabolism in gradients of various physicochemical cues. Despite the abundance chemoreceptors, little is known regarding exact contribution individual chemoreceptors lifestyle bacteria. Azospirillum brasilense are can fix atmospheric nitrogen under microaerophilic conditions. Here, we characterized a chemoreceptor this organism, named AerC, which functions as redox...
Elevated intracellular levels of the bacterial second messenger c-di-GMP are known to suppress motility and promote sessility. Bacterial chemotaxis guides motile cells in gradients attractants repellents over broad concentration ranges, thus allowing bacteria quickly adapt changes their surroundings. Here, we describe a receptor that enhances, as opposed suppresses, response temporary increases c-di-GMP. Azospirillum brasilense's preferred metabolism is adapted microaerophily, these navigate...
Ethylene is a plant hormone involved in many aspects of growth and development as well responses to stress. The role ethylene plant-microbe interactions has been explored from the perspective plants. However, only small number studies have examined microbes. We demonstrated that Azospirillum brasilense contains functional receptor we call Response1 (AzoEtr1) after nomenclature used AzoEtr1 directly binds with high affinity. Treating cells or disrupting reduces biofilm formation colonization...
ABSTRACT Azospirillum brasilense is plant-growth promoting rhizobacteria that produces the phytohormone indole-3-acetic acid (IAA) to induce changes in plant root architecture. The major pathway for IAA biosynthesis A. converts tryptophan into indole-3-pyruvic (I3P) and then, through rate-limiting enzyme, indole-3-pyruvate decarboxylase (IpdC), IAA. Here, we characterize potential role physiology of these bacteria by characterizing expression pattern ipdC promoter, analyzing an mutant using...
Motility responses triggered by changes in the electron transport system are collectively known as energy taxis. In Azospirillum brasilense, taxis was shown to be principal form of locomotor control. present study, we have identified a novel chemoreceptor-like protein, named Tlp1, which serves an transducer. The Tlp1 protein is predicted N-terminal periplasmic region and cytoplasmic C-terminal signaling module homologous those other chemoreceptors. comprises conserved domain that found two...
The Che1 chemotaxis-like pathway of Azospirillum brasilense contributes to chemotaxis and aerotaxis, it has also been found contribute regulating changes in cell surface adhesive properties that affect the propensity cells clump flocculate. exact contribution control flocculation A. remains poorly understood. Here, we show affects reversible cell-to-cell clumping, a cellular behavior which motile transiently interact by adhering one another at their nonflagellated poles before swimming...
The genomes of most motile bacteria encode two or more chemotaxis (Che) systems, but their functions have been characterized in only a few model systems. Azospirillum brasilense is soil alphaproteobacterium able to colonize the rhizosphere cereals. In response an attractant, A. cells transiently increase swimming speed and suppress reversals. Che1 pathway was previously shown regulate changes speed, it has minor role root surface colonization. Here, we show that second system, named Che4,...
Plant root exudates play critical roles in shaping rhizosphere microbial communities, and the ability of motile bacteria to respond these gradients mediates competitive colonization surfaces. Root are complex chemical mixtures that spatially temporally dynamic. Identifying exact chemical(s) recruitment soil specific regions roots is thus challenging. Here, we connect patterns bacterial chemotaxis responses sensing by chemoreceptors chemicals found exudate identify key signals shape surface...
The dimorphic prosthecate bacteria (DPB) are alpha-proteobacteria that reproduce in an asymmetric manner rather than by binary fission and of interest as simple models development. Prior to this work, the only member group for which genome sequence was available model freshwater organism Caulobacter crescentus. Here we describe Hyphomonas neptunium, a marine DPB differs from C. crescentus H. neptunium uses its stalk reproductive structure. Genome analysis indicates shares more genes with it...
ABSTRACT The ability of bacteria to monitor their metabolism and adjust behavior accordingly is critical maintain competitiveness in the environment. motile microaerophilic bacterium Azospirillum brasilense navigates oxygen gradients by aerotaxis order locate low concentrations that can support metabolism. When cells are exposed elevated levels surroundings, A. implement an alternative response form transient clumps cell-to-cell interactions. Clumping was suggested represent a protecting...
The genome of the Azorhizobium caulinodans ORS571 contains a unique chemotaxis gene cluster (che) including five genes: cheA, cheW, cheY 1 , cheB, and cheR. Analysis role A. using deletion mutant strains revealed that CheA or Che signaling pathway controls behavior flagella-driven motility plays important roles in formation biofilms production extracellular polysaccharides (EPS). Furthermore, mutants (ΔcheA ΔcheA-R) were defective competitive adsorption colonization on root surface host...
Azorhizobium caulinodans ORS571 is a free-living nitrogen-fixing bacterium which can induce nodules both on the root and stem of its legume host Sesbania rostrata This bacterium, an obligate aerobe that moves by means polar flagellum, possesses single chemotaxis signal transduction pathway. The objective this work was to examine role aerotaxis play in lifestyle symbiotic conditions. In bacterial chemotaxis, chemoreceptors sense environmental changes transmit information chemotactic machinery...