scholarly journals Bacillus mojavensis RRC101 Lipopeptides Provoke Physiological and Metabolic Changes During Antagonism Against Fusarium verticillioides

2016 ◽  
Vol 29 (9) ◽  
pp. 713-723 ◽  
Author(s):  
A. A. Blacutt ◽  
T. R. Mitchell ◽  
C. W. Bacon ◽  
S. E. Gold
Keyword(s):  
Antifungal Activity ◽  
Chemical Control ◽  
Fusarium Verticillioides ◽  
Endophytic Bacterium ◽  
Toxin Production ◽  
Maize Genome ◽  
Bacillus Mojavensis ◽  
Biochemical Assays ◽  
Biochemical Interaction ◽  
Pigment Accumulation

The mycotoxigenic pathogen Fusarium verticillioides threatens the quality and utility of maize across industrial and agricultural purposes. Chemical control is complicated by the intimate endophytic lifestyle of the pathogen with its host. Bacillus mojavensis RRC101, a maize-endophytic bacterium, has been observed to reduce F. verticillioides disease severity and fumonisin accumulation when coinoculated to maize. Genome sequencing and annotation identified a number of biocontrol-relevant pathways in RRC101. Biochemical assays confirmed the presence and activity of surfactin- and fengycin-type lipopeptides, with fengycins responsible for antifungal activity against F. verticillioides. This antagonism manifests as inhibition of filamentous growth, with microscopy revealing hyphal distortions, vacuolization, and lysis. F. verticillioides secondary metabolism also responds to antagonism, with lipopeptide challenge inducing greater fumonisin production and, in the case of fengycins, eliciting pigment accumulation at sites of inhibition. Together, these data suggest that antibiotic and toxin production are components of a complex biochemical interaction among maize endophytes, one pathogenic and one beneficial.

scholarly journals Antifungal activities of thiosemicarbazones and semicarbazones against mycotoxigenic fungi

2014 ◽  
Vol 38 (6) ◽  
pp. 531-537 ◽  
Author(s):  
Rojane de Oliveira Paiva ◽  
Lucimar Ferreira Kneipp ◽  
Carla Marins Goular ◽  
Mariana Almeida Albuquerque ◽  
Aurea Echevarria
Keyword(s):  
Antifungal Activity ◽  
Aspergillus Flavus ◽  
Fungicidal Activity ◽  
Fusarium Verticillioides ◽  
Animal Health ◽  
Fungistatic Activity ◽  
Mycotoxigenic Fungi ◽  
Quality Of Food ◽  
Chelating Effect

Mycotoxigenic fungi can compromise the quality of food, exposing human and animal health at risk. The antifungal activity of eight thiosemicarbazones (1-8) and nine semicarbazones (9-17) was evaluated against Aspergillus flavus, A. nomius, A. ochraceus, A. parasiticus and Fusarium verticillioides. Thiosemicarbazones had MIC values of 125-500 µg/ml. The thiosemicarbazones 1 and 2 exerted fungistatic activity against Aspergillus spp., and thiosemicarbazone 2 exerted fungicidal activity against F. verticillioides. Compound 2 showed an iron chelating effect of 63%. The ergosterol content of A. parasiticus had a decrease of 28 and 71% for the 31.2 and 62.5 µg/ml concentrations of thiosemicarbazone 2 compared to the control. The obtained results of antifungal activity revealed that thiosemicarbazone class was more active when compared to semicarbazone class and, the thiosemicarbazone 2 was the most active compound, specially, against Aspergillus spp.

Occidiofungin is the key metabolite for antifungal activity of the endophytic bacterium Burkholderia sp. MS455 against Aspergillus flavus

2021 ◽  
Author(s):  
Jiayuan Jia ◽  
Emerald Ford ◽  
Sarah Hobbs ◽  
Sonya Baird ◽  
Shien Lu
Keyword(s):  
Antifungal Activity ◽  
Aspergillus Flavus ◽  
Safety Concern ◽  
Regulatory Gene ◽  
Genomic Analysis ◽  
Endophytic Bacterium ◽  
Aflatoxin Contamination ◽  
Plant Production ◽  
Antifungal Compound ◽  
Buffer Control

Aflatoxin is a secondary metabolite produced by Aspergillus fungi and presents a major food safety concern globally. Among the available methods for prevention and control of aflatoxin, the application of antifungal bacteria has gained favorability in recent years. An endophytic bacterium MS455, isolated from soybean, exhibited broad-spectrum antifungal activity against economically important pathogens, including Aspergillus flavus. MS455 was identified as a strain of Burkholderia based on genomic analysis. Random and site-specific mutations were employed in discovery of the genes that share high homology to the ocf gene cluster of Burkholderia contaminans strain MS14, which is responsible for production of the antifungal compound occidiofungin. RNA-seq analysis demonstrated ORF1, a homolog to the ambR1 LuxR-type regulatory gene, regulates occidiofungin biosynthesis in MS455. Additionally, a total of 284 differentially expressed genes, including 138 up-regulated, and 146 down-regulated genes, suggesting that, in addition to its role in occidiofungin production, ORF1 is involved in expression of multiple genes, especially those involved in ornibactin biosynthesis. Plate bioassays showed the growth of A. flavus was significantly inhibited by the wild-type strain MS455 as compared with the ORF1 mutant. Similarly, corn kernel assays showed that growth of A. flavus and aflatoxin production were reduced significantly by MS455 as compared with buffer control and the ORF1 mutant. Collectively, the results demonstrated that production of occidiofungin is essential for antifungal activity of the endophytic bacterium MS455. This research has provided insights to understanding antifungal mechanisms of MS455 and development of biological approaches to prevent aflatoxin contamination in plant production.

scholarly journals Pseudomonas protegens MP12: A plant growth-promoting endophytic bacterium with broad-spectrum antifungal activity against grapevine phytopathogens

2019 ◽  
Vol 219 ◽  
pp. 123-131 ◽  
Author(s):  
Marco Andreolli ◽  
Giacomo Zapparoli ◽  
Elisa Angelini ◽  
Gianluca Lucchetta ◽  
Silvia Lampis ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Plant Growth ◽  
Broad Spectrum ◽  
Endophytic Bacterium ◽  
Plant Growth Promoting ◽  
Growth Promoting

scholarly journals Fumonisin and Beauvericin Chemotypes and Genotypes of the Sister Species Fusarium subglutinans and Fusarium temperatum

2020 ◽  
Vol 86 (13) ◽  
Author(s):  
M. Veronica Fumero ◽  
Alessandra Villani ◽  
Antonia Susca ◽  
Miriam Haidukowski ◽  
Maria T. Cimmarusti ◽  
...  
Keyword(s):  
Fusarium Verticillioides ◽  
Gene Clusters ◽  
Toxin Production ◽  
Sister Species ◽  
Ear Rot ◽  
Genome Sequences ◽  
Fusarium Subglutinans ◽  
Content Type ◽  
Close Phylogenetic Relationship ◽  
Fusarium Temperatum

ABSTRACT Fusarium subglutinans and Fusarium temperatum are common maize pathogens that produce mycotoxins and cause plant disease. The ability of these species to produce beauvericin and fumonisin mycotoxins is not settled, as reports of toxin production are not concordant. Our objective was to clarify this situation by determining both the chemotypes and genotypes for strains from both species. We analyzed 25 strains from Argentina, 13 F. subglutinans and 12 F. temperatum strains, for toxin production by ultraperformance liquid chromatography mass spectrometry (UPLC-MS). We used new genome sequences from two strains of F. subglutinans and one strain of F. temperatum, plus genomes of other Fusarium species, to determine the presence of functional gene clusters for the synthesis of these toxins. None of the strains examined from either species produced fumonisins. These strains also lack Fum biosynthetic genes but retain homologs of some genes that flank the Fum cluster in Fusarium verticillioides. None of the F. subglutinans strains we examined produced beauvericin although 9 of 12 F. temperatum strains did. A complete beauvericin (Bea) gene cluster was present in all three new genome sequences. The Bea1 gene was presumably functional in F. temperatum but was not functional in F. subglutinans due to a large insertion and multiple mutations that resulted in premature stop codons. The accumulation of only a few mutations expected to disrupt Bea1 suggests that the process of its inactivation is relatively recent. Thus, none of the strains of F. subglutinans or F. temperatum we examined produce fumonisins, and the strains of F. subglutinans examined also cannot produce beauvericin. Variation in the ability of strains of F. temperatum to produce beauvericin requires further study and could reflect the recent shared ancestry of these two species. IMPORTANCE Fusarium subglutinans and F. temperatum are sister species and maize pathogens commonly isolated worldwide that can produce several mycotoxins and cause seedling disease, stalk rot, and ear rot. The ability of these species to produce beauvericin and fumonisin mycotoxins is not settled, as reports of toxin production are not concordant at the species level. Our results are consistent with previous reports that strains of F. subglutinans produce neither fumonisins nor beauvericin. The status of toxin production by F. temperatum needs further work. Our strains of F. temperatum did not produce fumonisins, while some strains produced beauvericin and others did not. These results enable more accurate risk assessments of potential mycotoxin contamination if strains of these species are present. The nature of the genetic inactivation of BEA1 is consistent with its relatively recent occurrence and the close phylogenetic relationship of the two sister species.

scholarly journals Biosynthesis of Silver Nanoparticles Using Onion Endophytic Bacterium and Its Antifungal Activity against Rice Pathogen Magnaporthe oryzae

2020 ◽  
Vol 6 (4) ◽  
pp. 294
Author(s):  
Ezzeldin Ibrahim ◽  
Jinyan Luo ◽  
Temoor Ahmed ◽  
Wenge Wu ◽  
Chenqi Yan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Silver Nanoparticles ◽  
Antifungal Activity ◽  
Magnaporthe Oryzae ◽  
Fungal Infections ◽  
Endophytic Bacterium ◽  
Energy Dispersive Spectrum ◽  
Safe Alternative ◽  
Bacterium Bacillus ◽  
Biosynthesized Agnps

Biosynthesis of silver nanoparticles (AgNPs) using endophytic bacteria is a safe alternative to the traditional chemical method. The purpose of this research is to biosynthesize AgNPs using endophytic bacterium Bacillus endophyticus strain H3 isolated from onion. The biosynthesized AgNPs with sizes from 4.17 to 26.9 nm were confirmed and characterized by various physicochemical techniques such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), UV-visible spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) in addition to an energy dispersive spectrum (EDS) profile. The biosynthesized AgNPs at a concentration of 40 μg/mL had a strong antifungal activity against rice blast pathogen Magnaporthe oryzae with an inhibition rate of 88% in mycelial diameter. Moreover, the biosynthesized AgNPs significantly inhibited spore germination and appressorium formation of M. oryzae. Additionally, microscopic observation showed that mycelia morphology was swollen and abnormal when dealing with AgNPs. Overall, the current study revealed that AgNPs could protect rice plants against fungal infections.

Optimization of medium composition and culture conditions for antifungal activity of a tomato endophytic bacterium

2015 ◽  
Vol 82 ◽  
pp. 69-75 ◽  
Author(s):  
You-Jin Yi ◽  
Yu-sheng Li ◽  
Bo Xia ◽  
Wen-ping Li ◽  
Li Pang ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Endophytic Bacterium ◽  
Culture Conditions ◽  
Medium Composition

scholarly journals Inhibition of agronomically relevant fungal phytopathogens by tyrocidines, cyclic antimicrobial peptides isolated from Bacillus aneurinolyticus

Microbiology ◽  
2014 ◽  
Vol 160 (9) ◽  
pp. 2089-2101 ◽  
Author(s):  
Anscha M. Troskie ◽  
Abré de Beer ◽  
Johan A. Vosloo ◽  
Karin Jacobs ◽  
Marina Rautenbach
Keyword(s):  
Antifungal Activity ◽  
Salt Tolerance ◽  
Fusarium Solani ◽  
Fusarium Verticillioides ◽  
Membrane Integrity ◽  
Microscopic Analysis ◽  
Phytopathogenic Fungi ◽  
Main Mode ◽  
Sytox Green ◽  
Fungal Phytopathogens

The tyrocidines, a complex of analogous cyclic decapeptides produced by Bacillus aneurinolyticus, exhibited noteworthy activity against a range of phytopathogenic fungi, including Fusarium verticillioides, Fusarium solani and Botrytis cinerea. The activity of the tyrocidine peptide complex (Trc mixture) and purified tyrocidines exhibited minimum inhibition concentrations below 13 µg ml−1 (~10 µM) and was significantly more potent than that of the commercial imidazole fungicide, bifonazole. Although the tyrocidines’ activity was negatively influenced by the presence of Ca2+, it remained unaffected by the presence of Mg2+, Na+ and K+. Microscopic analysis revealed significant impact on the morphology of F. solani and Bot. cinerea including retarded germination and hyperbranching of hyphae. Studies with membrane-impermeable dyes, SYTOX green and propidium iodide suggested that the main mode of action of tyrocidines involves the disruption of fungal membrane integrity. Because of the tyrocidines’ broad spectrum and potent antifungal activity, possible multiple targets reducing the risk of overt resistance and general salt tolerance, they are promising candidates that warrant further investigation as bio-fungicides.

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