scholarly journals Production of Candicidin Isomers Is Essential for Biocontrol of Cucumber Rhizoctonia rot By Streptomyces albidoflavus W68

2021 ◽  
Author(s):  
Xueyan Yao ◽  
Zhenying Zhang ◽  
Jun Huang ◽  
Shiping Wei ◽  
Xianyun Sun ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Fungal Pathogens ◽  
Sequence Similarity ◽  
Gene Clusters ◽  
Core Gene ◽  
Fungal Diseases ◽  
Natural Soil ◽  
Streptomyces Albidoflavus ◽  
Biocontrol Activity ◽  
Microbial Biocontrol Agents

Diseases caused by soil-borne fungal pathogens result in significant crop yield losses and quality reduction. Streptomyces albidoflavus strain W68 is effective in controlling several soil-borne fungal diseases. To identify antifungal substances critical for biocontrol activity of W68, the genome of W68 was sequenced and a linear chromosome of 6.80 Mb was assembled. A total of 21 secondary metabolite biosynthesis gene clusters (BGCs), accounting for 12.27% of the genome, were identified. Core gene deletion mutants for each of all 8 BGCs for non-ribosomal peptide synthetases and polyketide synthases, were created. Among them, only the mutant lacking gene ctg1-5755 (the gene was renamed as fscDW68) in BGC 19, which shares 100% sequence similarity to the BGC for candicidin synthesis, showed obvious reduction in antifungal activity. A pot experiment revealed that biocontrol effects of the ΔfscDW68 mutant in Rhizoctonia rot of cucumber were also significantly compromised relative to W68. LC-MS analysis revealed that W68 but not ΔfscDW68 can produce candicidin isomers, indicating that the production of candicidin isomers is key for antifungal activity and biocontrol activity of S. albidoflavus W68. Importance This study provides the first report that candicidin-like secondary metabolites produced by microbial cells in natural soil environment can effectively control soil-borne fungal diseases, revealing a novel mechanism of microbial biocontrol agents. We demonstrated that the main antifungal activity and biocontrol activity of Streptomyces albidoflavus strain W68 is attributed to the production of candicidin isomers, suggesting gene clusters for candicidin-like compound biosynthesis might be used as molecular markers to screen and breed microbial strains for biocontrol agent development.

scholarly journals RpoN (σ54) Controls Production of Antifungal Compounds and Biocontrol Activity in Pseudomonas fluorescens CHA0

2005 ◽  
Vol 18 (3) ◽  
pp. 260-272 ◽  
Author(s):  
Maria Péchy-Tarr ◽  
Mélanie Bottiglieri ◽  
Sophie Mathys ◽  
Kirsten Bang Lejbølle ◽  
Ursula Schnider-Keel ◽  
...  
Keyword(s):  
Pseudomonas Fluorescens ◽  
Fungal Pathogens ◽  
Antibiotic Production ◽  
Nitrogen Sources ◽  
Pythium Ultimum ◽  
Natural Soil ◽  
Root Diseases ◽  
Enhanced Production ◽  
Biocontrol Activity ◽  
Pathogen Suppression

Pseudomonas fluorescens CHA0 is an effective biocontrol agent of root diseases caused by fungal pathogens. The strain produces the antibiotics 2,4-diacetylphloroglucinol (DAPG) and pyoluteorin (PLT) that make essential contributions to pathogen suppression. This study focused on the role of the sigma factor RpoN (σ54) in regulation of antibiotic production and biocontrol activity in P. fluorescens. An rpoN in-frame-deletion mutant of CHA0 had a delayed growth, was impaired in the utilization of several carbon and nitrogen sources, and was more sensitive to salt stress. The rpoN mutant was defective for flagella and displayed drastically reduced swimming and swarming motilities. Interestingly, the rpoN mutant showed a severalfold enhanced production of DAPG and expression of the biosynthetic gene phlA compared with the wild type and the mutant complemented with monocopy rpoN+. By contrast, loss of RpoN function resulted in markedly lowered PLT production and plt gene expression, suggesting that RpoN controls the balance of the two antibiotics in strain CHA0. In natural soil microcosms, the rpoN mutant was less effective in protecting cucumber from a root rot caused by Pythium ultimum. Remarkably, the mutant was not significantly impaired in its root colonization capacity, even at early stages of root infection by Pythium spp. Taken together, our results establish RpoN for the first time as a major regulator of biocontrol activity in Pseudomonas fluorescens.

scholarly journals Biodirected Synthesis of Silver Nanoparticles Using Aqueous Honey Solutions and Evaluation of Their Antifungal Activity against Pathogenic Candida Spp.

2021 ◽  
Vol 22 (14) ◽  
pp. 7715
Author(s):  
Grzegorz Czernel ◽  
Dominika Bloch ◽  
Arkadiusz Matwijczuk ◽  
Jolanta Cieśla ◽  
Monika Kędzierska-Matysek ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Antifungal Activity ◽  
Fungal Pathogens ◽  
Fungal Growth ◽  
Disc Diffusion ◽  
Candida Spp ◽  
Antifungal Effect ◽  
Synthesis Of Nanoparticles ◽  
Honey Solution ◽  
Diffusion Assay

Silver nanoparticles (AgNPs) were synthesized using aqueous honey solutions with a concentration of 2%, 10%, and 20%—AgNPs-H2, AgNPs-H10, and AgNPs-H20. The reaction was conducted at 35 °C and 70 °C. Additionally, nanoparticles obtained with the citrate method (AgNPs-C), while amphotericin B (AmB) and fluconazole were used as controls. The presence and physicochemical properties of AgNPs was affirmed by analyzing the sample with ultraviolet–visible (UV–Vis) and fluorescence spectroscopy, scanning electron microscopy (SEM), and dynamic light scattering (DLS). The 20% honey solution caused an inhibition of the synthesis of nanoparticles at 35 °C. The antifungal activity of the AgNPs was evaluated using opportunistic human fungal pathogens Candida albicans and Candida parapsilosis. The antifungal effect was determined by the minimum inhibitory concentration (MIC) and disc diffusion assay. The highest activity in the MIC tests was observed in the AgNPs-H2 variant. AgNPs-H10 and AgNPs-H20 showed no activity or even stimulated fungal growth. The results of the Kirby–Bauer disc diffusion susceptibility test for C. parapsilosis strains indicated stronger antifungal activity of AgNPs-H than fluconazole. The study demonstrated that the antifungal activity of AgNPs is closely related to the concentration of honey used for the synthesis thereof.

scholarly journals Characterization of the Aerobic Anoxygenic Phototrophic Bacterium Sphingomonas sp. AAP5

2021 ◽  
Vol 9 (4) ◽  
pp. 768
Author(s):  
Karel Kopejtka ◽  
Yonghui Zeng ◽  
David Kaftan ◽  
Vadim Selyanin ◽  
Zdenko Gardian ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Sequence Similarity ◽  
Orthologous Gene ◽  
Gene Clusters ◽  
Rrna Gene ◽  
Unidentified Phospholipid ◽  
Respiratory Quinone ◽  
Polar Lipid Profile ◽  
Close Phylogenetic Relationship

An aerobic, yellow-pigmented, bacteriochlorophyll a-producing strain, designated AAP5 (=DSM 111157=CCUG 74776), was isolated from the alpine lake Gossenköllesee located in the Tyrolean Alps, Austria. Here, we report its description and polyphasic characterization. Phylogenetic analysis of the 16S rRNA gene showed that strain AAP5 belongs to the bacterial genus Sphingomonas and has the highest pairwise 16S rRNA gene sequence similarity with Sphingomonas glacialis (98.3%), Sphingomonas psychrolutea (96.8%), and Sphingomonas melonis (96.5%). Its genomic DNA G + C content is 65.9%. Further, in silico DNA-DNA hybridization and calculation of the average nucleotide identity speaks for the close phylogenetic relationship of AAP5 and Sphingomonas glacialis. The high percentage (76.2%) of shared orthologous gene clusters between strain AAP5 and Sphingomonas paucimobilis NCTC 11030T, the type species of the genus, supports the classification of the two strains into the same genus. Strain AAP5 was found to contain C18:1ω7c (64.6%) as a predominant fatty acid (>10%) and the polar lipid profile contained phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, sphingoglycolipid, six unidentified glycolipids, one unidentified phospholipid, and two unidentified lipids. The main respiratory quinone was ubiquinone-10. Strain AAP5 is a facultative photoheterotroph containing type-2 photosynthetic reaction centers and, in addition, contains a xathorhodopsin gene. No CO2-fixation pathways were found.

scholarly journals Rhizosphere-enriched microbes as a pool to design synthetic communities for reproducible beneficial outputs

2019 ◽  
Author(s):  
Maria-Dimitra Tsolakidou ◽  
Ioannis A Stringlis ◽  
Natalia Fanega-Sleziak ◽  
Stella Papageorgiou ◽  
Antria Tsalakou ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Fungal Pathogens ◽  
Growth Parameters ◽  
Tomato Plants ◽  
Beneficial Effects ◽  
Negative Effect ◽  
Tomato Growth ◽  
In Vitro Antifungal Activity

Abstract Composts represent a sustainable way to suppress diseases and improve plant growth. Identification of compost-derived microbial communities enriched in the rhizosphere of plants and characterization of their traits, could facilitate the design of microbial synthetic communities (SynComs) that upon soil inoculation could yield consistent beneficial effects towards plants. Here, we characterized a collection of compost-derived bacteria, previously isolated from tomato rhizosphere, for in vitro antifungal activity against soil-borne fungal pathogens and for their potential to change growth parameters in Arabidopsis. We further assessed root-competitive traits in the dominant rhizospheric genus Bacillus. Certain isolated rhizobacteria displayed antifungal activity against the tested pathogens and affected growth of Arabidopsis, and Bacilli members possessed several enzymatic activities. Subsequently, we designed two SynComs with different composition and tested their effect on Arabidopsis and tomato growth and health. SynCom1, consisting of different bacterial genera, displayed negative effect on Arabidopsis in vitro, but promoted tomato growth in pots. SynCom2, consisting of Bacilli, didn't affect Arabidopsis growth, enhanced tomato growth and suppressed Fusarium wilt symptoms. Overall, we found selection of compost-derived microbes with beneficial properties in the rhizosphere of tomato plants, and observed that application of SynComs on poor substrates can yield reproducible plant phenotypes.

A GacS deficiency does not affectPseudomonas chlororaphisPA23 fitness when growing on canola, in aged batch culture or as a biofilm

2006 ◽  
Vol 52 (12) ◽  
pp. 1177-1188 ◽  
Author(s):  
N Poritsanos ◽  
C Selin ◽  
W G.D Fernando ◽  
S Nakkeeran ◽  
T.R. de Kievit
Keyword(s):  
Antifungal Activity ◽  
Batch Culture ◽  
Hydrogen Cyanide ◽  
Fungal Pathogen ◽  
Biocontrol Agent ◽  
Antifungal Compounds ◽  
Pseudomonas Chlororaphis ◽  
Wild Type ◽  
Biocontrol Activity ◽  
Competition Assays

Pseudomonas chlororaphis PA23 is a biocontrol agent that protects against the fungal pathogen Sclerotinia sclerotiorum. Employing transposon mutagenesis, we isolated a gacS mutant that no longer exhibited antifungal activity. Pseudomonas chlororaphis PA23 was previously reported to produce the nonvolatile antibiotics phenazine 1-carboxylic acid and 2-hydroxyphenazine. We report here that PA23 produces additional compounds, including protease, lipase, hydrogen cyanide, and siderophores, that may contribute to its biocontrol ability. In the gacS mutant background, generation of these products was markedly reduced or delayed with the exception of siderophores, which were elevated. Not surprisingly, this mutant was unable to protect canola from disease incited by S. sclerotiorum. The gacS mutant was able to sustain itself in the canola phyllosphere, therefore, the loss of biocontrol activity can be attributed to a reduced production of antifungal compounds and not a declining population size. Competition assays between the mutant and wild type revealed equivalent fitness in aged batch culture; consequently, the gacS mutation did not impart a growth advantage in the stationary phase phenotype. Under minimal nutrient conditions, the gacS-deficient strain produced a tenfold less biofilm than the wild type. However, no difference was observed in the ability of the mutant biofilm to protect cells from lethal antibiotic challenge.Key words: Pseudomonas, biocontrol, gacS, fitness, biofilms.

scholarly journals Antifungal Efficacy of Marine Macroalgae against Fungal Isolates from Bronchial Asthmatic Cases

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 3032 ◽  
Author(s):  
Suresh Mickymaray ◽  
Wael Alturaiki
Keyword(s):  
Antifungal Activity ◽  
Fungal Pathogens ◽  
Fungal Infections ◽  
Algal Species ◽  
Marine Macroalgae ◽  
Minimum Fungicidal Concentration ◽  
Asthmatic Patients ◽  
The Cost ◽  
Algal Extracts ◽  
Airway Colonization

Fungal sensitization is very common in bronchial asthmatic cases, and the connection with airway colonization by fungi remains uncertain. Antifungal therapy failure is a significant fraction of the cost and morbidity and mortality in the majority of the asthmatic cases. Hence, the present study aimed to investigate the antifungal activity of five marine macroalgae—Acanthaophora specifera, Cladophoropsis sp., Laurencia paniculata, Tydemania sp., and Ulva prolifera—which were tested on selected fungal pathogens isolated from 15 sputum of 45 bronchial asthmatic patients. The highest antifungal activity was observed in ethanol fractions of L. paniculata followed by U. prolifera, Cladophoropsis sp., A. specifera, and Tydemania sp. The minimum fungicidal concentration and minimum inhibitory concentration values of the ethanolic fractions of algal species were found to be 125–1000 µg/mL and 125–500 µg/mL, respectively. The algal extracts contained terpene alcohol, diterpene, steroids, sesquiterpene, and sesquiterpene alcohol, as determined by GC–MS/MS analyses. The present study shows that the marine macroalgae containing bioactive compounds had excellent inhibitory activity against a variety of fungal pathogens, which may be useful for combating fungal infections and recovering from chronic asthmatic states.

scholarly journals The emergence of cereal fungal diseases and the incidence of leaf spot diseases in Finland

2008 ◽  
Vol 20 (1) ◽  
pp. 62 ◽  
Author(s):  
M. JALLI ◽  
P. LAITINEN ◽  
S. LATVALA
Keyword(s):  
Spring Wheat ◽  
Leaf Spot ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Field Survey ◽  
Fungal Diseases ◽  
Cochliobolus Sativus ◽  
Pyrenophora Tritici Repentis ◽  
Fungal Plant Pathogens ◽  
First Time

Fungal plant pathogens causing cereal diseases in Finland have been studied by a literature survey, and a field survey of cereal leaf spot diseases conducted in 2009. Fifty-seven cereal fungal diseases have been identified in Finland. The first available references on different cereal fungal pathogens were published in 1868 and the most recent reports are on the emergence of Ramularia collo-cygni and Fusarium langsethiae in 2001. The incidence of cereal leaf spot diseases has increased during the last 40 years. Based on the field survey done in 2009 in Finland, Pyrenophora teres was present in 86%, Cochliobolus sativus in 90% and Rhynchosporium secalis in 52% of the investigated barley fields. Mycosphaerella graminicola was identified for the first time in Finnish spring wheat fields, being present in 6% of the studied fields. Stagonospora nodorum was present in 98% and Pyrenophora tritici-repentis in 94% of spring wheat fields. Oat fields had the fewest fungal diseases. Pyrenophora chaetomioides was present in 63% and Cochliobolus sativus in 25% of the oat fields studied.;

scholarly journals Antifungal activity of pinosylvin fromPinus densifloraon turfgrass fungal diseases

2017 ◽  
Vol 60 (3) ◽  
pp. 213-218 ◽  
Author(s):  
Dong Gu Lee ◽  
Seong Jun Lee ◽  
Joyce P. Rodriguez ◽  
Ik Hwi Kim ◽  
Taehyun Chang ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Fungal Diseases

scholarly journals Complete Genome Sequences of Five Burkholderia Strains with Biocontrol Activity against Various Lettuce Pathogens

2022 ◽  
Author(s):  
Adrien Biessy ◽  
Marie Ciotola ◽  
Mélanie Cadieux ◽  
Daphné Albert ◽  
Martin Filion
Keyword(s):  
Complete Genome ◽  
Burkholderia Cepacia ◽  
Gene Clusters ◽  
Antimicrobial Compounds ◽  
Bacterial Strains ◽  
Genome Sequences ◽  
Biosynthetic Gene Clusters ◽  
Content Type ◽  
Biocontrol Activity ◽  
Complex Display

Numerous bacterial strains from the Burkholderia cepacia complex display biocontrol activity. Here, we report the complete genome sequences of five Burkholderia strains isolated from soil. Biosynthetic gene clusters responsible for the production of antimicrobial compounds were found in the genome of these strains, which display biocontrol activity against various lettuce pathogens.

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