Factors affecting adsorption of Azospirillum brasilense Cd to root hairs as compared with root surface of wheat

1989 ◽  
Vol 35 (10) ◽  
pp. 936-944 ◽  
Author(s):  
Yoav Bashan ◽  
Hanna Levanony
Keyword(s):  
Azospirillum Brasilense ◽  
Root Hairs ◽  
Growth Conditions ◽  
Root Surface ◽  
Logarithmic Phase ◽  
Bacterial Cells ◽  
Beneficial Bacteria ◽  
Factors Affecting ◽  
Associative Bacteria ◽  
Bacterial Adsorption

Electron microscopy of wheat (Triticum aestivum) roots inoculated with Azospirillum brasilense Cd revealed massive adsorption of bacterial cells to the root surface and less adsorption to root hairs. Quantitative analysis of A. brasilense Cd adsorption to root surface and to root hairs, confirmed qualitatively by light microscopy observations, revealed a bacterial adsorption ratio of 5 (+2): 1 (root surface: root hairs). Extreme bacterial adsorption ratios were recorded when bacteria were previously grown in the presence of KNO3 (27:1) or when bacterial cells were inoculated under hydroponic plant growth conditions (80:1). Adsorption of A. brasilense Cd to roots was directly related to the bacterial growth phase, with logarithmic phase cultures demonstrating a greater adsorption than stationary phase cultures. Adsorption to root hairs was dependent mainly on the number of root hairs developed under certain growth conditions. When very few root hairs had developed, most of the bacterial cells were adsorbed to the root surface. Factors such as starvation, bacteria grown in culture in the presence of KNO3, addition of several nutrients, and protease or NaEDTA treatments of bacterial cells before the adsorption assay decreased bacterial adsorption to root hairs. Other factors such as microaerophilic growth conditions, addition of several bacterial chemoattractants, and cellulase-treated root hairs enhanced bacterial adsorption. It is proposed that although A. brasilense Cd adsorbed to every part of the root system, more cells adsorbed to the root surface of wheat than to the root hairs.Key words: associative bacteria, Azospirillum, bacterial adsorption, beneficial bacteria, rhizosphere bacteria, root-hair colonization.

Changes in root morphology of wheat caused by Azospirillum inoculation

1985 ◽  
Vol 31 (10) ◽  
pp. 881-887 ◽  
Author(s):  
Yoram Kapulnik ◽  
Yaacov Okon ◽  
Yigel Henis
Keyword(s):  
Cross Sections ◽  
Azospirillum Brasilense ◽  
Root Elongation ◽  
Root Hairs ◽  
Triticum Aestivum L ◽  
Wheat Root ◽  
Root Surface ◽  
Scanning Electron Micrographs ◽  
Bacterial Cells ◽  
Colony Forming Units

Wheat seeds (Triticum aestivum L.) were inoculated with Azospirillum brasilense Cd, Sp7, the local isolate Cd-1, and with other types of bacteria. Inoculation with 105 to 106 colony-forming units of Azospirillum caused the largest root elongation and total root surface of seedlings whereas 108 to 109 colony-forming units of Azospirillum caused inhibition of root development. Similar effects were obtained in 10 different cultivars of wheat inoculated with Azospirillum. Scanning electron micrographs of inoculated wheat root segments showed denser and longer root hairs as compared with the control inoculated with dead cells. This effect was less apparent in more mature roots. In inoculated roots bacteria were located mainly on the cell elongation area and on the bases of root hairs, but fewer bacterial cells were present on the root cap or adsorbed to root hairs. Cross sections of Azospirillum-inoculated roots showed prominent alterations of the cell arrangement in the layers of the cortex. The results suggest the existence of critical numbers of sites for Azospirillum colonization on the roots, to such an extent that root growth is affected.

scholarly journals Revealing the Metabolic Alterations during Biofilm Development of Burkholderia cenocepacia Based on Genome-Scale Metabolic Modeling

Metabolites ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 221
Author(s):  
Ozlem Altay ◽  
Cheng Zhang ◽  
Hasan Turkez ◽  
Jens Nielsen ◽  
Mathias Uhlén ◽  
...  
Keyword(s):  
Systems Biology ◽  
Alternative Pathway ◽  
Growth Conditions ◽  
Pentose Phosphate ◽  
Burkholderia Cenocepacia ◽  
Bacterial Cells ◽  
Metabolic Remodeling ◽  
Transcriptomics Data ◽  
Biofilm Development ◽  
Genome Scale

Burkholderia cenocepacia is among the important pathogens isolated from cystic fibrosis (CF) patients. It has attracted considerable attention because of its capacity to evade host immune defenses during chronic infection. Advances in systems biology methodologies have led to the emergence of methods that integrate experimental transcriptomics data and genome-scale metabolic models (GEMs). Here, we integrated transcriptomics data of bacterial cells grown on exponential and biofilm conditions into a manually curated GEM of B. cenocepacia. We observed substantial differences in pathway response to different growth conditions and alternative pathway susceptibility to extracellular nutrient availability. For instance, we found that blockage of the reactions was vital through the lipid biosynthesis pathways in the exponential phase and the absence of microenvironmental lysine and tryptophan are essential for survival. During biofilm development, bacteria mostly had conserved lipid metabolism but altered pathway activities associated with several amino acids and pentose phosphate pathways. Furthermore, conversion of serine to pyruvate and 2,5-dioxopentanoate synthesis are also identified as potential targets for metabolic remodeling during biofilm development. Altogether, our integrative systems biology analysis revealed the interactions between the bacteria and its microenvironment and enabled the discovery of antimicrobial targets for biofilm-related diseases.

Cytological and histochemical characteristics of the axenic root surface of Alnus glutinosa

1986 ◽  
Vol 64 (10) ◽  
pp. 2216-2226 ◽  
Author(s):  
Yves Prin ◽  
Mireille Rougier
Keyword(s):  
Cell Wall ◽  
Root Hair ◽  
Root Hairs ◽  
Root Apex ◽  
Alnus Glutinosa ◽  
Root Surface ◽  
Infection Process ◽  
Root Cap ◽  
A Cell ◽  
Histochemical Tests

The aim of the present study was to investigate the Alnus root surface using seedlings grown axenically. This study has focused on root zones where infection by the symbiotic actinomycete Frankia takes place. The zones examined extend from the root cap to the emerging root hair zone. The root cap ensheaths the Alnus root apex and extends over the root surface as a layer of highly flattened cells closely appressed to the root epidermal cell wall. These cells contain phenolic compounds as demonstrated by various histochemical tests. They are externally bordered by a thin cell wall coated by a thin mucilage layer. The root cap is ruptured when underlying epidermal cells elongate, and cell remnants are still found in the emerging root hair zone. Young emerging root hairs are bordered externally by a cell wall covered by a thin mucilage layer which reacts positively to the tests used for the detection of polysaccharides, glycoproteins, and anionic sites. The characteristics of the Alnus root surface and the biological function of mucilage and phenols present at the root surface are discussed in relation to the infection process.

Factors Influencing Geosmin Production by the Cyanobacterium Oscillatoria Brevis

1988 ◽  
Vol 20 (8-9) ◽  
pp. 125-131 ◽  
Author(s):  
H. Naes ◽  
H. C. Utkilen ◽  
A. F. Post
Keyword(s):  
Environmental Factors ◽  
Dry Weight ◽  
Growth Conditions ◽  
Limited Extent ◽  
Limited Growth ◽  
Pigment Synthesis ◽  
Factors Affecting ◽  
Culture Techniques ◽  
Factors Influencing ◽  
Effect Of Inhibitors

Environmental factors affecting geosmin production by Oscillatoria brevis have been investigated under laboratory conditions using continuous culture techniques. Transition from light to nutrient limited growth conditions caused a two-fold decrease in geosmin production. However, geosmin content increased relative to pigment content (chlorophyll a and carotenoids). It has been suggested that geosmin biosynthesis in O. brevis proceeds via the isoprenoid pathway as was found in actinomycetes. Accordingly, we investigated the effect of inhibitors of the intermediate stages in this synthetic pathway in order to study the regulation of geosmin production in relation to pigment synthesis. It was concluded that geosmin seemed to function as an overflow metabolite in this pathway. Due to the only modest changes in geosmin production per dry weight compared to changes in biomass levels during light- or nutrient limited growth, contamination of eutrophic fresh waters with geosmin appears to depend mainly on the species present and its biomass level and only to a limited extent on nutrient enhanced synthesis.

Structure and ontogeny of Betula alleghaniensis – Pisolithus tinctorius ectomycorrhizae

1990 ◽  
Vol 68 (3) ◽  
pp. 579-593 ◽  
Author(s):  
H. B. Massicotte ◽  
R. L. Peterson ◽  
C. A. Ackerley ◽  
L. H. Melville
Keyword(s):  
Root Hairs ◽  
Root Surface ◽  
Pisolithus Tinctorius ◽  
Initial Contact ◽  
Broad Host Range ◽  
Betula Alleghaniensis ◽  
Cortical Cells ◽  
Structural Modifications ◽  
Hartig Net ◽  
Primary Roots

The ontogeny and ultrastructure of ectomycorrhizae synthesized between Betula alleghaniensis (yellow birch) and Pisolithus tinctorius, a broad host range fungus, were studied to determine the structural modifications in both symbionts during ectomycorrhiza establishment. A number of stages, including initial contact of hyphae with the root surface, early mantle formation, and mature mantle formation, were distinguished. Interactions between hyphae and root hairs were frequent. As a paraepidermal Hartig net developed, root epidermal cells elongated in a radial direction, but wall ingrowths were not formed. Repeated branching of Hartig net hyphae resulted in extensive fine branches and the compartmentalization of hyphal cytoplasm. Nuclei and elongated mitochondria were frequently located in the narrow cytoplasmic compartments, and [Formula: see text] thickenings developed along walls of cortical cells in primary roots.

scholarly journals Factors affecting transport of bacterial cells in porous media

1990 ◽  
Author(s):  
A Mills ◽  
J Herman ◽  
G Hornberger
Keyword(s):  
Porous Media ◽  
Bacterial Cells ◽  
Factors Affecting

Ultrastructure of interaction in alginate beads between the microalgaChlorella vulgariswith its natural associative bacteriumPhyllobacterium myrsinacearumand with the plant growth-promoting bacteriumAzospirillum brasilense

2001 ◽  
Vol 47 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Vladimir K Lebsky ◽  
Luz E Gonzalez-Bashan ◽  
Yoav Bashan
Keyword(s):  
Wastewater Treatment ◽  
Plant Growth ◽  
Azospirillum Brasilense ◽  
Bacterial Species ◽  
Alginate Beads ◽  
Transmission Electron ◽  
Associative Bacteria ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Treatment Water

Chlorella vulgaris, a microalga often used in wastewater treatment, was coimmobilized and coincubated either with the plant growth-promoting bacterium Azospirillum brasilense, or with its natural associative bacterium Phyllobacterium myrsinacearum, in alginate beads designed for advanced wastewater treatment. Interactions between the microalga and each of the bacterial species were followed using transmission electron microscopy for 10 days. Initially, most of the small cavities within the beads were colonized by microcolonies of only one microorganism, regardless of the bacterial species cocultured with the microalga. Subsequently, the bacterial and microalgal microcolonies merged to form large, mixed colonies within the cavities. At this stage, the effect of bacterial association with the microalga differed depending on the bacterium present. Though the microalga entered a senescence phase in the presence of P. myrsinacearum, it remained in a growth phase in the presence of A. brasilense. This study suggests that there are commensal interactions between the microalga and the two plant associative bacteria, and that with time the bacterial species determined whether the outcome for the microalga is senescence or continuous multiplication.Key words: Azospirillum, Chlorella, Phyllobacterium, wastewater treatment, water bioremediation.

Analysis of the Crushing Effect about Ultrasound on E. coli and B. subtilis

2012 ◽  
Vol 260-261 ◽  
pp. 1017-1021
Author(s):  
Xin Ying Wang ◽  
Yong Tao Liu ◽  
Min Hui ◽  
Ji Fei Xu
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Bacillus Subtilis ◽  
Bacterial Cell ◽  
Logarithmic Phase ◽  
Growth Stages ◽  
Bacterial Cells ◽  
E Coli ◽  
Different Growth Stages ◽  
Main Factor

Escherichia coli and Bacillus subtilis as objects of the study, ultrasonic fragmentation acted on the bacterial cells in different growth stages, results showed that, it’s similar to the crushing effect of ultrasound on E. coli and B. subtilis cells of different growth stages, the highest crushing rate in the logarithmic phase, reached to 95.8% and 94.3% respectively, the crushing rate of adjustment phase is lowest, maintained at around 60%, the crushing rate stability cell was centered, which can be achieved 90%. The structure of the bacterial cell wall didn’t the main factor to decide the ultrasonic fragmentation effect, but different growth periods of bacterial cells did the determinant.

Rhythmic patterns of nutrient acquisition by wheat roots

2002 ◽  
Vol 29 (5) ◽  
pp. 595 ◽  
Author(s):  
Sergey Shabala ◽  
Andrew Knowles
Keyword(s):  
Root Zone ◽  
Root Hairs ◽  
Rhythmic Activity ◽  
Root Apex ◽  
Root Surface ◽  
Ion Flux ◽  
Nutrient Acquisition ◽  
Wheat Roots ◽  
Non Invasive ◽  
Functional Zone

Oscillatory patterns in H+, K+, Ca2+ and Cl- uptake were observed at different regions of the root surface, including root hairs, using a non-invasive ion flux measuring technique (the MIFE™ technique). To our knowledge, this is the first report of ultradian oscillations in nutrient acquisition in the mature root zone. Oscillations of the largest magnitude were usually measured in the elongation region, 2–4 mm from the root apex. There were usually at least two oscillatory components present for each ion measured: fast, with periods of several minutes; and slow, with periods of 50–80 min. Even within the same functional zone, the periods of ion flux oscillations were significantly different, suggesting that they are driven by some internal mechanisms located in each cell rather than originating from one ‘central clock pacemaker’. There were also significant changes in the oscillatory characteristics (both periods and amplitudes) of fluxes from a single small cluster of cells over time. Analysis of phase shifts between oscillations in different ions suggested that rhythmic activity of a plasma membrane H+-pump may be central to observed rhythmic nutrient acquisition by plant roots. We discuss the possible adaptive significance of such an oscillatory strategy for root nutrient acquisition.

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