ABSTRACT
Microbial bio-products are becoming an appealing and viable alternative to chemical pesticides for effective management of crop diseases. These bio-products are known to have potential to minimize agrochemical applications without losing crop yield and also restore soil fertility and productivity. In this study, the inhibitory efficacy of 2,4-diacetylphloroglucinol (DAPG) produced by Pseudomonas fluorescens VSMKU3054 against Ralstonia solanacearum was assessed. Biochemical and functional characterization study revealed that P. fluorescens produced hydrogen cyanide (HCN), siderophore, indole acetic acid (IAA) and hydrolytic enzymes such as amylase, protease, cellulase and chitinase, and had the ability to solubilize phosphate. The presence of the key antimicrobial encoding gene in the biosynthesis of 2,4-diacetylphloroglucinol (DAPG) was identified by PCR. The maximum growth and antimicrobial activity of P. fluorescens was observed in king's B medium at pH 7, 37 °C and 36 h of growth. Glucose and tryptone were found to be the most suitable carbon and nitrogen sources, respectively. DAPG was separated by silica column chromatography and identified by various methods such as UV-Vis, FT-IR, GC-MS and NMR spectroscopy. When R. solanacearum cells were exposed to DAPG at 90 µg/mL, the cell viability was decreased, reactive oxygen species (ROS) were increased and chromosomal DNA was damaged. Application of P. fluorescens and DAPG significantly reduced the bacterial wilt incidence. In addition, P. fluorescens was also found effective in promoting the growth of tomato seedlings. It is concluded that the indigenous isolate P. fluorescens VSMKU3054 could be used as a suitable biocontrol agent against bacterial wilt disease of tomato.
ABSTRACT
We report on the synthesis and characterization of trans N, N'-di-substituted macrocyclic "tet a" probe (L) for metal ion sensing. Both the colorimetric and fluorescent titration studies are performed with different metal ions. The results have suggested that the probe L is very selective and sensitive towards Zn2+ ions with significant changes in color. The pendant armed macrocyclic "tet a" probe has exhibited 1.28× 105 M-1 binding constant and virtuous selectivity for Zn2+ ion than other common metal ions. The detection limit of the probe towards Zn2+ ion is 0.027 nM. The selective sensing of Zn2+ ion is efficiently reversible with EDTA, which is demonstrated for five cycles without losing sensitivity. The time-resolved single-photon counting (TCSPC) studies have determined the average lifetime value for the probe L and L+ Zn2+ ion of 1.29 and 2.96 ns, respectively. The theoretical DFT studies have well supported the experimental outcomes. The practical application of the probe in visualizing intracellular Zn2+ ion distribution in live Artemia salina has proved the low cytotoxicity and cell membrane permeability of probe, which makes it capable of sensing Zn2+ ion in HeLa cells. Thus, the probe L can act as a selective recognition of Zn2+ ion in living cell applications.
Subject(s)
Cells/ultrastructure , Coloring Agents/chemistry , Coordination Complexes/chemistry , Macrocyclic Compounds/chemistry , Zinc/chemistry , Animals , Anti-Bacterial Agents/chemistry , Artemia , Biocompatible Materials/chemistry , Biosensing Techniques , Cations, Divalent/chemistry , Cell Membrane Permeability , Cell Survival , Density Functional Theory , HeLa Cells , Humans , Kinetics , Larva , Ligands , Optical Imaging , Sensitivity and SpecificityABSTRACT
Novel isonicotinic acid hydrazide functionalized silver nanoparticles (INH-AgNPs) were synthesized by wet chemical method and used for the detection of Hg2+ ions in aqueous medium. The INH-AgNPs exhibit good absorbance and emission peaks by sensing Hg2+ ions with visible color changes. The detection of Hg2+ ions was confirmed by FT-IR, EDAX spectra and by the changing morphology of INH-AgNPs, and after addition of Hg2+ was confirmed by SEM and TEM imaging studies. Based on the emission intensity the probe INH-AgNPs exhibit a lowest detection limit (LOD) of Hg2+ to 0.18 nM. The association constant (Ka) of INH-AgNPs + Hg2+ ions is calculated using the Bensei-Hildebrand equation. Also, the probe is successfully utilized for the detection of Hg2+ ions in real water samples obtained from different fields, which showed good results.
ABSTRACT
Rhodamine diaminomaleonitrile linked probe (RD-1) shows highly sensitive colorimetric and selective turn-on fluorescent response to Cd2+ over other metal ions. The fluorescence intensity and absorbance of the probe RD-1 showed a good linearity, with very low detection limits of 18.5 nm. The probe RD-1 was preliminarily applied to the determination of Cd2+ ion in water samples from river and tap water with satisfying results. The live cell image confocal microscopy, HeLa cell demonstrated that RD-1 had low cytotoxicity with good membrane permeable property is successfully applied to fluorescence microscopic imaging for the detection of Cd2+ ions.
Subject(s)
Biosensing Techniques/methods , Cadmium/analysis , Colorimetry/methods , Fluorescence , Nitriles/chemistry , Rhodamines/chemistry , Spectrometry, Fluorescence/methods , Cell Survival , Fluorescent Dyes/chemistry , HeLa Cells , Humans , Limit of Detection , Microscopy, Confocal , Optical Imaging/methodsABSTRACT
Synthesis of enone core based dendrimers with carbazole as surface group has been achieved. All the synthesized dendrimers showed excellent antioxidant behavior with commercially available 1,1-diphenyl-2-picryl hydrazyl (DPPH).
Subject(s)
Antioxidants/chemistry , Carbazoles/chemistry , Dendrimers/chemistry , Antioxidants/chemical synthesis , Biphenyl Compounds/chemistry , Carbazoles/chemical synthesis , Dendrimers/chemical synthesis , Molecular Structure , Picrates/chemistry , Surface PropertiesABSTRACT
A series of carbazole based macrocyclic diamides with thia and oxy linkages have been synthesized and the inhibitory activity of the cyclophane amides against human pathogenic bacteria and plant pathogenic fungi are documented. (S)-1,10-Bi-2-naphthol [(S)-BINOL] based chiral carbazolophane amide emerged as the most interesting compound in this series exhibiting excellent antibacterial and antifungal activities.
Subject(s)
Amides/chemistry , Amides/pharmacology , Anti-Infective Agents/chemistry , Anti-Infective Agents/pharmacology , Carbazoles/chemistry , Drug Design , Macrocyclic Compounds/chemistry , Amides/chemical synthesis , Anti-Infective Agents/chemical synthesis , Bacteria/drug effects , Fungi/drug effects , Humans , Models, Molecular , Molecular Conformation , Plants/microbiologyABSTRACT
Synthesis of fluorescent imidazole-based dicationic carbazolophanes incorporating various spacer units is described. Interestingly, the cyclophanes 2a and 5a incorporating a pyridine moiety exhibited superior antibacterial activity against most of the pathogenic bacteria in the tested concentrations as compared to the other cyclophanes as well as the test control, benzalkonium chloride (BAC), cetylpyridinium chloride (CPC) and tetracycline.
