scholarly journals Identification and Characterization of a Hexapeptide with Activity Against Phytopathogenic Fungi That Cause Postharvest Decay in Fruits

2000 ◽  
Vol 13 (8) ◽  
pp. 837-846 ◽  
Author(s):  
Belén López-García ◽  
Luis González-Candelas ◽  
Enrique Pérez-Payá ◽  
Jose F. Marcos
Keyword(s):  
Antimicrobial Activity ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Plant Protection ◽  
Phytopathogenic Fungi ◽  
Bacterial Strains ◽  
General Sequence ◽  
Postharvest Decay ◽  
Structure Conservation

A hexapeptide of amino acid sequence Ac-Arg-Lys-Thr-Trp-Phe-Trp-NH 2 was demonstrated to have antimicrobial activity against selected phytopathogenic fungi that cause postharvest decay in fruits. The peptide synthesized with either all D- or all L-amino acids inhibited the in vitro growth of strains of Penicillium italicum, P. digitatum, and Botrytis cinerea, with MICs of 60 to 80 μM and 50% inhibitory concentration (IC50) of 30 to 40 μM. The inhibitory activity of the peptide was both sequence- and fungus-specific since (i) sequence-related peptides lacked activity (including one with five residues identical to the active sequence), (ii) other filamentous fungi (including some that belong to the genus Penicillium) were insensitive to the peptide's antifungal action, and (iii) the peptide did not inhibit the growth of several yeast and bacterial strains assayed. Experiments on P. digitatum identified conidial germination as particularly sensitive to inhibition although mycelial growth was also affected. Our findings suggest that the inhibitory effect is initially driven by the electrostatic interaction of the peptide with fungal components. The antifungal peptide retarded the blue and green mold diseases of citrus fruits and the gray mold of tomato fruits under controlled inoculation conditions, thus providing evidence for the feasibility of using very short peptides in plant protection. This and previous studies with related peptides indicate some degree of peptide amino acid sequence and structure conservation associated with the antimicrobial activity, and suggest a general sequence layout for short antifungal peptides, consisting of one or two positively charged residues combined with aromatic amino acid residues.

An Antimicrobial Peptide from the Australian Native Hardenbergia violacea Provides the First Functionally Characterised Member of a Subfamily of Plant Defensins

1997 ◽  
Vol 24 (5) ◽  
pp. 571 ◽  
Author(s):  
Stuart J. Harrison ◽  
John P. Marcus ◽  
Kenneth C. Goulter ◽  
Jodie L. Green ◽  
Donald J. Maclean ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Antimicrobial Peptide ◽  
Mammalian Cells ◽  
Amino Acid Sequences ◽  
Plant Defensin ◽  
Defensive Role ◽  
Plant Defensins

An antimicrobial peptide (HvAMP1) was isolated from seeds of the Australian native legume Hardenbergia violacea (Schneev.) Stearn. The peptide is 47 amino acid residues in length, contains 8 cysteines, and has a molecular weight of 5392 and a predicted pI of 10.41. HvAMP1 inhibited the growth of several plant pathogenic fungi at concentrations as low as 1 µM in vitro and produced distinct hyphal distortion and increased branching. This antimicrobial activity was greatly diminished in the presence of 1 mM CaCl2 and 50 mM KCl. The purified peptide at 40 µM did not inhibit three different a-amylase enzymes. Aeukaryotic cell-free translation system showed inhibition approaching 50% in the presence of ~100 µM of HvAMP1. The viability of plant and mammalian cells cultured in vitro was not adversely affected by concentrations of HvAMP1 as high as 40 mM. The amino acid sequence of HvAMP1 contained the consensus amino acids that define the plant defensin family of peptides. The HvAMP1 amino acid sequence showed 87% and 57% identity with the amino acid sequences deduced from cDNA sequences from defensins of Vigna unguiculata and Pisum sativum, respectively. Other plant defensin sequences showed less than 33% amino acid identity to the peptide. Therefore, HvAMP1 and the putative plant defensins of cowpea and pea define a distinct sequence subfamily of plant defensins which is at present limited to members of the Fabaceae. HvAMP1 is the first member of this subfamily to be purified and functionally characterised. The antimicrobial activity of HvAMP1 suggests a defensive role for this subfamily of peptides.

scholarly journals IN VITRO FORMATION OF ASSOCIATED BIOFILMS BY TRICHODERMA SPP. AND PLANT GROWTH PROMOTING BACTERIA (PGPB)

ÈKOBIOTEH ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 324-330
Author(s):  
N.F. Galimzianova ◽  
◽  
G.E. Aktuganov ◽  
T.F. Boyko ◽  
E.A. Gilavnova ◽  
...  
Keyword(s):  
Plant Protection ◽  
Phytopathogenic Fungi ◽  
Plant Residues ◽  
Fungal Mycelium ◽  
Plant Growth Promoting Bacteria ◽  
Bacterial Strains ◽  
Trichoderma Spp ◽  
Yield Increase ◽  
Plant Growth Promoting

The capability to formation of combined biofilms by the fungi from Trichoderma genus and several PGP-bacteria including Pseudomonas extremaustralis, P. koreensis, P. mandelii and Advenella kashmirensis has been demonstrated. The strains of Trichoderma used in the experiment not only exert antagonism to phytopathogenic fungi, but also accelerate the decomposition of plant residues. It was found that microscopic fungi whose mycelial structure offers advantages in reaching and assimilating of nutrient substrates, during their growth can favor to directional moving of bacteria cells. The explored bacterial strains moved along the fungal mycelium on the surface of the medium, and in areas where the medium was absent, the bacteria moved inside the hyphae, leaving them when the mycelium reached the substrate. The findings evidence the potential of considered microorganisms for developing of a new generation multifunctional biopreparation for agriculture, contributing not only to crop yield increase and plant protection against phytopathogenic fungi, but also maintaining soil fertility.

scholarly journals Fabrication and Characterization of Antimicrobial Magnetron Cosputtered TiO2/Ag/Cu Composite Coatings

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 473
Author(s):  
Dilyana Gospodonova ◽  
Iliana Ivanova ◽  
Todorka Vladkova
Keyword(s):  
Antimicrobial Activity ◽  
Composite Coatings ◽  
Surface Characteristics ◽  
Standard Test ◽  
Most Probable Number ◽  
Bacterial Strains ◽  
Probable Number ◽  
Fabrication And Characterization

The aim of this study was to prepare TiO2/Ag/Cu magnetron co-sputtered coatings with controlled characteristics and to correlate them with the antimicrobial activity of the coated glass samples. The elemental composition and distribution, surface morphology, wettability, surface energy and its component were estimated as the surface characteristics influencing the bioadhesion. Well expressed, specific, Ag/Cu concentration-dependent antimicrobial activity in vitro was demonstrated toward Gram-negative and Gram-positive standard test bacterial strains both by diffusion 21 assay and by Most Probable Number of surviving cells. Direct contact and eluted silver/coper nanoparticles killing were experimentally demonstrated as a mode of the antimicrobial action of the studied TiO2/Ag/Cu thin composite coatings. It is expected that they would ensure a broad spectrum bactericidal activity during the indwelling of the coated medical devices and for at least 12 h after that, with the supposition that the benefits will be over a longer time.

scholarly journals Novel Amino Acid Derivatives of Quinolines as Potential Antibacterial and Fluorophore Agents

2020 ◽  
Vol 88 (4) ◽  
pp. 57
Author(s):  
Oussama Moussaoui ◽  
Rajendra Bhadane ◽  
Riham Sghyar ◽  
El Mestafa El Hadrami ◽  
Soukaina El Amrani ◽  
...  
Keyword(s):  
Amino Acid ◽  
Methyl Esters ◽  
Amino Acid Derivatives ◽  
Bacterial Strains ◽  
Fluorescent Properties ◽  
Topoisomerase Iv ◽  
Microdilution Method ◽  
Hydrolysis Of ◽  
Derivatives Of

A new series of amino acid derivatives of quinolines was synthesized through the hydrolysis of amino acid methyl esters of quinoline carboxamides with alkali hydroxide. The compounds were purified on silica gel by column chromatography and further characterized by TLC, NMR and ESI-TOF mass spectrometry. All compounds were screened for in vitro antimicrobial activity against different bacterial strains using the microdilution method. Most of the synthesized amino acid-quinolines show more potent or equipotent inhibitory action against the tested bacteria than their correspond esters. In addition, many of them exhibit fluorescent properties and could possibly be utilized as fluorophores. Molecular docking and simulation studies of the compounds at putative bacterial target enzymes suggest that the antimicrobial potency of these synthesized analogues could be due to enzyme inhibition via their favorable binding at the fluoroquinolone binding site at the GyrA subunit of DNA gyrase and/or the ParC subunit of topoisomerase-IV.

scholarly journals Catalytic and Molecular Properties of the Quinohemoprotein Tetrahydrofurfuryl Alcohol Dehydrogenase from Ralstonia eutropha Strain Bo

2001 ◽  
Vol 183 (6) ◽  
pp. 1954-1960 ◽  
Author(s):  
Grit Zarnt ◽  
Thomas Schräder ◽  
Jan R. Andreesen
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Alcohol Dehydrogenase ◽  
Tertiary Structure ◽  
Ralstonia Eutropha ◽  
Signal Sequence ◽  
Substrate Inhibition ◽  
Catalytic Efficiency ◽  
Gene Encoding

ABSTRACT The quinohemoprotein tetrahydrofurfuryl alcohol dehydrogenase (THFA-DH) from Ralstonia eutropha strain Bo was investigated for its catalytic properties. The apparentk cat/Km andK i values for several substrates were determined using ferricyanide as an artificial electron acceptor. The highest catalytic efficiency was obtained with n-pentanol exhibiting a k cat/Km value of 788 × 104 M−1 s−1. The enzyme showed substrate inhibition kinetics for most of the alcohols and aldehydes investigated. A stereoselective oxidation of chiral alcohols with a varying enantiomeric preference was observed. Initial rate studies using ethanol and acetaldehyde as substrates revealed that a ping-pong mechanism can be assumed for in vitro catalysis of THFA-DH. The gene encoding THFA-DH from R. eutropha strain Bo (tfaA) has been cloned and sequenced. The derived amino acid sequence showed an identity of up to 67% to the sequence of various quinoprotein and quinohemoprotein dehydrogenases. A comparison of the deduced sequence with the N-terminal amino acid sequence previously determined by Edman degradation analysis suggested the presence of a signal sequence of 27 residues. The primary structure of TfaA indicated that the protein has a tertiary structure quite similar to those of other quinoprotein dehydrogenases.

scholarly journals Phytochemical investigation and in vitro antimicrobial activity of Richardia scabra

2016 ◽  
Vol 11 (2) ◽  
pp. 248 ◽  
Author(s):  
Kathirvel Poonkodi ◽  
Subban Ravi
Keyword(s):  
Antimicrobial Activity ◽  
Diffusion Method ◽  
Bacterial Strains ◽  
Weed Species ◽  
Antibacterial And Antifungal Activities ◽  
Agar Plug ◽  
Phytochemical Investigation ◽  
Antibacterial And Antifungal ◽  
Simple Sugar

<p class="Abstract">The present study was aimed to evaluate the phytochemical screening and antimicrobial activity of the petroleum ether and methanol extracts from the mature leaves of <em>Richardia scabra</em> from India. Disc diffusion method was used to determine the zone inhibition of the tested samples for antibacterial and agar plug method was used to determine the antifungal activity, while the microtube-dilution technique was used to determine the minimum inhibitory concentration. Both extracts showed significant antibacterial and antifungal activities when tested against 10 bacterial and four fungal strains. The minimum inhibitory concentrations of the methanol extract of<em> R. scabra</em> ranged between 12.5–100 μg/mL for bacterial strains. Alkaloids, steroids, flavonoids, fatty acids, terpenoids and simple sugar were detected as phytoconstituents of extracts. To the best of our knowledge, this is the first report against antimicrobial activity of common weed species <em>R. scabra</em> found in India.</p><p> </p>

scholarly journals Polymeric Nanoparticles Active against Dual-Species Bacterial Biofilms

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 4958
Author(s):  
Jessa Marie V. Makabenta ◽  
Jungmi Park ◽  
Cheng-Hsuan Li ◽  
Aritra Nath Chattopadhyay ◽  
Ahmed Nabawy ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Laser Scanning ◽  
Polymeric Nanoparticles ◽  
Bacterial Species ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Bacterial Biofilms ◽  
Global Public Health ◽  
Bacterial Strains

Biofilm infections are a global public health threat, necessitating new treatment strategies. Biofilm formation also contributes to the development and spread of multidrug-resistant (MDR) bacterial strains. Biofilm-associated chronic infections typically involve colonization by more than one bacterial species. The co-existence of multiple species of bacteria in biofilms exacerbates therapeutic challenges and can render traditional antibiotics ineffective. Polymeric nanoparticles offer alternative antimicrobial approaches to antibiotics, owing to their tunable physico-chemical properties. Here, we report the efficacy of poly(oxanorborneneimide) (PONI)-based antimicrobial polymeric nanoparticles (PNPs) against multi-species bacterial biofilms. PNPs showed good dual-species biofilm penetration profiles as confirmed by confocal laser scanning microscopy. Broad-spectrum antimicrobial activity was observed, with reduction in both bacterial viability and overall biofilm mass. Further, PNPs displayed minimal fibroblast toxicity and high antimicrobial activity in an in vitro co-culture model comprising fibroblast cells and dual-species biofilms of Escherichia coli and Pseudomonas aeruginosa. This study highlights a potential clinical application of the presented polymeric platform.

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