scholarly journals How a Taxonomically-Ambiguous Cyanobiont and Vanadate Assist in the Phytoremediation of Cadmium by Azolla pinnata: Implications for CKDu

2018 ◽  
Vol 7 (1) ◽  
pp. 53 ◽  
Author(s):  
D R A M T R Atugoda ◽  
L L U Mandakini ◽  
N J G J Bandara ◽  
D Gunawardana
Keyword(s):  
Nitrogen Fixation ◽  
Ex Situ ◽  
Twilight Zone ◽  
Azolla Pinnata ◽  
Gram Negative ◽  
Stepping Stone ◽  
Physiological Cost ◽  
Homocitrate Synthase ◽  
Assisted Phytoremediation ◽  
Dependent Mechanism

We employed scientific tools to investigate the ex situ phytoremediation of cadmium by Azolla pinnata. Azolla pinnata was capable of efficient sequestration of cadmium up to a concentration of 1 ppm, though with a visibly high “physiological cost”. The sequestration of cadmium (1 ppm) was strongly reduced after 24 hours, in Azolla plants pre-treated with the gram-negative antibiotic erythromycin (60 µg/l), suggesting that the cyanobacterial population was important for phytoremediation. Only the co-treatment of 1 ppm cadmium with 1 ppm vanadate, showed significantly higher phytoremediation (P<0.05) compared to the “cadmium+erythromycin” treatment. The phytoremediation of Cadmium by the Azolla-Nostoc symbiosis was significantly (p<0.05) improved by the addition of citrate at 10 ppm in the presence of 1 ppm vanadate, compared to the 1 ppm cadmium only treatment. We hypothesize that citrate acting either as “vanadophores” or working as a cofactor in the Homocitrate Synthase enzyme, facilitates remediation of cadmium. When phylogeny was inferred using Homocitrate Synthases, the cyanobiont was approximated to a taxonomical twilight zone between Nostoc and Anabaena, although showing more proximity to the Anabaena cluster. It is proposed here that the cyanobacterial contribution appears to be crucial for the ability of Azolla pinnata to efficiently remediate cadmium and a “helping hand” appears to be provided by a vanadate dependent mechanism, which is likely to be nitrogen fixation. The association between vanadate-assisted phytoremediation by Azolla pinnata and the heightened bioavailability of vanadium in CKDu endemic areas, could serve as a vital stepping stone in developing a biological solution to CKDu.

scholarly journals The Quorum Sensing Auto-Inducer 2 (AI-2) Stimulates Nitrogen Fixation and Favors Ethanol Production over Biomass Accumulation in Zymomonas mobilis

2021 ◽  
Vol 22 (11) ◽  
pp. 5628
Author(s):  
Valquíria Campos Alencar ◽  
Juliana de Fátima dos Santos Silva ◽  
Renata Ozelami Vilas Boas ◽  
Vinícius Manganaro Farnézio ◽  
Yara N. L. F. de Maria ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Quorum Sensing ◽  
Ethanol Production ◽  
N2 Fixation ◽  
Energy Demand ◽  
Zymomonas Mobilis ◽  
Biomass Accumulation ◽  
High Energy ◽  
Gram Negative ◽  
Expression Of Genes

Autoinducer 2 (or AI-2) is one of the molecules used by bacteria to trigger the Quorum Sensing (QS) response, which activates expression of genes involved in a series of alternative mechanisms, when cells reach high population densities (including bioluminescence, motility, biofilm formation, stress resistance, and production of public goods, or pathogenicity factors, among others). Contrary to most autoinducers, AI-2 can induce QS responses in both Gram-negative and Gram-positive bacteria, and has been suggested to constitute a trans-specific system of bacterial communication, capable of affecting even bacteria that cannot produce this autoinducer. In this work, we demonstrate that the ethanologenic Gram-negative bacterium Zymomonas mobilis (a non-AI-2 producer) responds to exogenous AI-2 by modulating expression of genes involved in mechanisms typically associated with QS in other bacteria, such as motility, DNA repair, and nitrogen fixation. Interestingly, the metabolism of AI-2-induced Z. mobilis cells seems to favor ethanol production over biomass accumulation, probably as an adaptation to the high-energy demand of N2 fixation. This opens the possibility of employing AI-2 during the industrial production of second-generation ethanol, as a way to boost N2 fixation by these bacteria, which could reduce costs associated with the use of nitrogen-based fertilizers, without compromising ethanol production in industrial plants.

scholarly journals Growth and nitrogen fixation in Azolla pinnata under field conditions

1982 ◽  
Vol 10 (2) ◽  
pp. 205 ◽  
Author(s):  
S. A. Kulasooriya ◽  
W. K. Hirimburegama ◽  
S. W. Abeysekara
Keyword(s):  
Nitrogen Fixation ◽  
Field Conditions ◽  
Azolla Pinnata

scholarly journals Complete Genome Sequence of Rhizobium japonicum Podophage Pasto

2021 ◽  
Vol 10 (3) ◽  
Author(s):  
Nikhil Manuel ◽  
Leika Rushing ◽  
Aravind Ravindran ◽  
Heather Newkirk ◽  
Ben Burrowes ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
Genomic Analysis ◽  
Rhizobium Japonicum ◽  
Negative Bacterium ◽  
Significant Similarity ◽  
Gram Negative ◽  
Content Type

ABSTRACT Rhizobium japonicum is a Gram-negative bacterium of interest for research into nitrogen fixation in legumes. This article describes the isolation, sequencing, and annotation of R. japonicum podophage Pasto. While it shows no significant similarity to identified phages, genomic analysis indicates that Pasto may be temperate and is a novel T7-like podophage.

Characterization of a nitrogen-fixing bacterial strain from the roots of Digitaria sanguinalis

1976 ◽  
Vol 22 (2) ◽  
pp. 254-260 ◽  
Author(s):  
Lynn E. Barber ◽  
Harold J. Evans
Keyword(s):  
Nitrogen Fixation ◽  
Bacterial Strain ◽  
Optimal Growth ◽  
Root Systems ◽  
Mixed Cultures ◽  
Nitrogen Fixing ◽  
Digitaria Sanguinalis ◽  
Gram Negative ◽  
Root Sample

Rates of nitrogen fixation of 3 to 10 g of N2 fixed per hectare per day were associated with root systems of Digitaria sanguinalis. A Gram-negative motile aerobic bacterial strain that was capable of N2 fixation was isolated from a washed root sample of one of these plants. Optimal growth and N2 fixation occurred at a pH of about 6.5, a temperature of 30–37 °C, and at a pO2 of about 0.01 atm. Increased rates of N2 fixation resulted when this strain was grown in mixed cultures with aerobic or facultative bacteria. Observations of cellular and cultural morphology and results of biochemical and physiological studies indicate that the isolate may be related to the Azotobacteraceae but that it is not identical with any of the members of this family. The importance of N2 fixation by this isolate in nature is unknown.

scholarly journals Effects of Disruption of Homocitrate Synthase Genes on Nostoc sp. Strain PCC 7120 Photobiological Hydrogen Production and Nitrogenase

2007 ◽  
Vol 73 (23) ◽  
pp. 7562-7570 ◽  
Author(s):  
Hajime Masukawa ◽  
Kazuhito Inoue ◽  
Hidehiro Sakurai
Keyword(s):  
Nitrogen Fixation ◽  
Hydrogen Production ◽  
Double Mutant ◽  
Production Systems ◽  
Combined Nitrogen ◽  
Nitrogen Fixation Activity ◽  
Production Activity ◽  
Homocitrate Synthase ◽  
High Level ◽  
Pcc 7120

ABSTRACT In the case of nitrogenase-based photobiological hydrogen production systems of cyanobacteria, the inactivation of uptake hydrogenase (Hup) leads to significant increases in hydrogen production activity. However, the high-level-activity stage of the Hup mutants lasts only a few tens of hours under air, a circumstance which seems to be caused by sufficient amounts of combined nitrogen supplied by active nitrogenase. The catalytic FeMo cofactor of nitrogenase binds homocitrate, which is required for efficient nitrogen fixation. It was reported previously that the nitrogenase from the homocitrate synthase gene (nifV) disruption mutant of Klebsiella pneumoniae shows decreased nitrogen fixation activity and increased hydrogen production activity under N2. The cyanobacterium Nostoc sp. strain PCC 7120 has two homocitrate synthase genes, nifV1 and nifV2, and with the ΔhupL variant of Nostoc sp. strain PCC 7120 as the parental strain, we have constructed two single mutants, the ΔhupL ΔnifV1 strain (with the hupL and nifV1 genes disrupted) and the ΔhupL ΔnifV2 strain, and a double mutant, the ΔhupL ΔnifV1 ΔnifV2 strain. Diazotrophic growth rates of the two nifV single mutants and the double mutant were decreased moderately and severely, respectively, compared with the rates of the parent ΔhupL strain. The hydrogen production activity of the ΔhupL ΔnifV1 mutant was sustained at higher levels than the activity of the parent ΔhupL strain after about 2 days of combined-nitrogen step down, and the activity in the culture of the former became higher than that in the culture of the latter. The presence of N2 gas inhibited hydrogen production in the ΔhupL ΔnifV1 ΔnifV2 mutant less strongly than in the parent ΔhupL strain and the ΔhupL ΔnifV1 and ΔhupL ΔnifV2 mutants. The alteration of homocitrate synthase activity can be a useful strategy for improving sustained photobiological hydrogen production in cyanobacteria.

scholarly journals Nitrogen Fixation by Gram-Negative Bacteria

Nature ◽  
1958 ◽  
Vol 182 (4639) ◽  
pp. 891-891 ◽  
Author(s):  
MICHAEL H. PROCTOR ◽  
P. W. WILSON
Keyword(s):  
Nitrogen Fixation ◽  
Gram Negative Bacteria ◽  
Gram Negative

scholarly journals In situ proteolysis of theVibrio choleraematrix protein RbmA promotes biofilm recruitment

2015 ◽  
Vol 112 (33) ◽  
pp. 10491-10496 ◽  
Author(s):  
Daniel R. Smith ◽  
Manuel Maestre-Reyna ◽  
Gloria Lee ◽  
Harry Gerard ◽  
Andrew H.-J. Wang ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
3D Structure ◽  
Limited Proteolysis ◽  
Crystallographic Structure ◽  
Gram Negative ◽  
The Matrix ◽  
Biofilm Structure ◽  
Biofilm Matrix ◽  
Dependent Mechanism

The estuarine gram-negative rod and human diarrheal pathogenVibrio choleraesynthesizes a VPS exopolysaccharide-dependent biofilm matrix that allows it to form a 3D structure on surfaces. Proteins associated with the matrix include, RbmA, RbmC, and Bap1. RbmA, a protein whose crystallographic structure suggests two binding surfaces, associates with cells by means of a VPS-dependent mechanism and promotes biofilm cohesiveness and recruitment of cells to the biofilm. Here, we show that RbmA undergoes limited proteolysis within the biofilm. This proteolysis, which is carried out by the hemagglutinin/protease and accessory proteases, yields the 22-kDa C-terminal polypeptide RbmA*. RbmA* remains biofilm-associated. Unlike full-length RbmA, the association of RbmA* with cells is no longer VPS-dependent, likely due to an electropositive surface revealed by proteolysis. We provide evidence that this proteolysis event plays a role in recruitment of VPS−cells to the biofilm surface. Based on our findings, we propose that association of RbmA with the matrix reinforces the biofilm structure and leads to limited proteolysis of RbmA to RbmA*. RbmA*, in turn, promotes recruitment of cells that have not yet initiated VPS synthesis to the biofilm surface. The assignment of two functions to RbmA, separated by a proteolytic event that depends on matrix association, dictates an iterative cycle in which reinforcement of recently added biofilm layers precedes the recruitment of new VPS−cells to the biofilm.

scholarly journals Antibacterial Cotton Fabric Functionalized with Copper Oxide Nanoparticles

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5802
Author(s):  
Luz E. Román ◽  
Enrique D. Gomez ◽  
José L. Solís ◽  
Mónica M. Gómez
Keyword(s):  
Cupric Oxide ◽  
Antimicrobial Properties ◽  
Copper Oxide Nanoparticles ◽  
Cuo Nanoparticles ◽  
Ex Situ ◽  
Gram Negative Bacteria ◽  
Bacterial Strains ◽  
Gram Negative ◽  
Structure And Morphology

Textiles functionalized with cupric oxide (CuO) nanoparticles have become a promising option to prevent the spread of diseases due to their antimicrobial properties, which strongly depend on the structure and morphology of the nanoparticles and the method used for the functionalization process. This article presents a review of work focused on textiles functionalized with CuO nanoparticles, which were classified into two groups, namely, in situ and ex situ. Moreover, the analyzed bacterial strains, the resistance of the antimicrobial properties of textiles to washing processes, and their cytotoxicity were identified. Finally, the possible antimicrobial mechanisms that could develop in Gram-positive and Gram-negative bacteria were described.

Sign in / Sign up

Export Citation Format

Share Document