scholarly journals Biocontrol of Avocado Dematophora Root Rot by Antagonistic Pseudomonas fluorescens PCL1606 Correlates With the Production of 2-Hexyl 5-Propyl Resorcinol

2006 ◽  
Vol 19 (4) ◽  
pp. 418-428 ◽  
Author(s):  
Francisco M. Cazorla ◽  
Simon B. Duckett ◽  
Ed T. Bergström ◽  
Sadaf Noreen ◽  
Roeland Odijk ◽  
...  
Keyword(s):  
Pseudomonas Fluorescens ◽  
Root Rot ◽  
Hydrolytic Enzymes ◽  
Test System ◽  
Phytopathogenic Fungi ◽  
Antagonistic Activity ◽  
Antifungal Metabolites ◽  
Antifungal Antibiotics ◽  
Biocontrol Activity ◽  
Tn5 Mutants

A collection of 905 bacterial isolates from the rhizospheres of healthy avocado trees was obtained and screened for antagonistic activity against Dematophora necatrix, the cause of avocado Dematophora root rot (also called white root rot). A set of eight strains was selected on the basis of growth inhibitory activity against D. necatrix and several other important soilborne phytopathogenic fungi. After typing of these strains, they were classified as belonging to Pseudomonas chlororaphis, Pseudomonas fluorescens, and Pseudomonas putida. The eight antagonistic Pseudomonas spp. were analyzed for their secretion of hydrogen cyanide, hydrolytic enzymes, and antifungal metabolites. P. chlororaphis strains produced the antibiotic phenazine-1-carboxylic acid and phenazine-1-carboxamide. Upon testing the biocontrol ability of these strains in a newly developed avocado-D. necatrix test system and in a tomato-F. oxysporum test system, it became apparent that P. fluorescens PCL1606 exhibited the highest biocontrol ability. The major antifungal activity produced by strain P. fluorescens PCL1606 did not correspond to any of the major classes of antifungal antibiotics produced by Pseudomonas biocontrol strains. This compound was purified and subsequently identified as 2-hexyl 5-propyl resorcinol (HPR). To study the role of HPR in biocontrol activity, two Tn5 mutants of P. fluorescens PCL1606 impaired in antagonistic activity were selected. These mutants were shown to impair HRP production and showed a decrease in biocontrol activity. As far as we know, this is the first report of a Pseudomonas biocontrol strain that produces HPR in which the production of this compound correlates with its biocontrol activity.

scholarly journals Antifungal activity of indigenous bacillus sp. isolate Q3 against marshmallow mycobiota

2011 ◽  
pp. 111-120
Author(s):  
Dragana Josic ◽  
Radmila Pivic ◽  
Snezana Pavlovic ◽  
Sasa Stojanovic ◽  
Goran Aleksic ◽  
...  
Keyword(s):  
Hydrolytic Enzymes ◽  
Pathogenic Fungi ◽  
Phytopathogenic Fungi ◽  
Bacterial Suspension ◽  
Dual Culture ◽  
Seed Infection ◽  
Bacillus Sp ◽  
Antifungal Metabolites ◽  
Parasitic Fungi ◽  
Plant Growth Promoting

Marshmallow is a host of a number of saprophytic and parasitic fungi in Serbia. The seeds of marshmallow are contaminated with fungi from different genera, especially Alternaria and Fusarium, which significantly reduced seed germination and caused seedling decay. In this study we investigate antagnonism of indigenous Bacillus sp. isolate Q3 against marshmallow mycopopulation. Bacillus sp. Q3 was isolated from maize rhizosphere, characterized by polyphasic approch and tested for plant growth promoting treats. Bacillus sp. Q3 produced antifungal metabolites with growth inhibition activity against numerous fungi in dual culture: 61.8% of Alternaria alternata, 74.8% of Myrothecium verrucaria and 33.6% of Sclerotinia sclerotiorum. That effect could be caused by different antifungal metabolites including siderophores, hydrolytic enzymes, organic acids and indole acetic acid (IAA). Suppression of natural marshmallow seed infection by Q3 isolate was observed. The seeds were immersed in different concentrations of bacterial suspension during 2h and their infections by phytopathogenic fungi were estimated. The results showed significant reduction of seed infection by Alternaria spp. The presented results indicate possible application of this isolate as promising biological agent for control of marshmallow seed pathogenic fungi.

scholarly journals Biocontrol Traits of Pseudomonas spp. Are Regulated by Phase Variation

2003 ◽  
Vol 16 (11) ◽  
pp. 1003-1012 ◽  
Author(s):  
Daan van den Broek ◽  
Thomas F. C. Chin-A-Woeng ◽  
Kevin Eijkemans ◽  
Ine H. M. Mulders ◽  
Guido V. Bloemberg ◽  
...  
Keyword(s):  
Phase I ◽  
Phase Ii ◽  
Phase Variation ◽  
Antagonistic Activity ◽  
Vital Role ◽  
Disease Suppression ◽  
Gene Encoding ◽  
Antifungal Metabolites ◽  
Biocontrol Activity ◽  
Take All

Of 214 Pseudomonas strains isolated from maize rhizosphere, 46 turned out to be antagonistic, of which 43 displayed clear colony phase variation. The latter strains formed both opaque and translucent colonies, designated as phase I and phase II, respectively. It appeared that important biocontrol traits, such as motility and the production of antifungal metabolites, proteases, lipases, chitinases, and biosurfactants, are correlated with phase I morphology and are absent in bacteria with phase II morphology. From a Tn5luxAB transposon library of Pseudomonas sp. strain PCL1171 phase I cells, two mutants exhibiting stable expression of phase II had insertions in gacS. A third mutant, which showed an increased colony phase variation frequency was mutated in mutS. Inoculation of wheat seeds with PCL1171 bacteria of phase I morphology resulted in efficient suppression of take-all disease, whereas disease suppression was absent with phase II bacteria. Neither the gacS nor the mutS mutant was able to suppress take-all, but biocontrol activity was restored after genetic complementation of these mutants. Furthermore, in a number of cases, complementation by gacS of wild-type phase II sectors to phase I phenotype could be shown. A PCL1171 phase I mutant defective in antagonistic activity appeared to have a mutation in a gene encoding a lipopeptide synthetase homologue and had lost its biocontrol activity, suggesting that biocontrol by strain PCL1171 is dependent on the production of a lipopeptide. Our results show that colony phase variation plays a regulatory role in biocontrol by Pseudomonas bacteria by influencing the expression of major biocontrol traits and that the gacS and mutS genes play a role in the colony phase variation process. Therefore phase variation not only plays a role in escaping animal defense but it also appears to play a much broader and vital role in the ecology of bacteria producing exoenzymes, antibiotics, and other secondary metabolites.

scholarly journals Chromatographic profiles of antifungal exo- and endometabolites of Bacillus velezensis

2021 ◽  
Vol 2(26) ◽  
pp. 191-199
Author(s):  
T.M. Sidorova ◽  
◽  
A.M. Asaturova ◽  
V.V. Allakhverdyan ◽  
◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Fusarium Oxysporum ◽  
Phytopathogenic Fungi ◽  
Antagonistic Activity ◽  
Active Metabolites ◽  
Fungicidal Action ◽  
Antifungal Metabolites ◽  
Alternaria Sp ◽  
Tlc Analysis

The antifungal activity of the Bacillus bacteria is based on their ability to produce metabolites. Therefore, when selecting a strain that produces an effective biofungicide, it is necessary to assess the metabolism of bacteria. The aim of this work is to isolate exo- and endometabolites of the promising B. velezensis BZR 336g and B. velezensis BZR 517 strains and assess their antifungal activity. Studies were carried out in 2020–2021. The object of the study is a liquid culture of the B. velezensis BZR 336g and B. velezensis BZR 517 strains. Methods of liquid extraction, ascending thin layer chromatography (TLC), bioautography with a test-culture of Fusarium oxysporum var. orthoceras and Alternaria sp. fungi were used to analyze metabolites. The ability of the strains to accumulate a complex of active metabolites showing antifungal effect from fungistatic to fungicidal action was revealed. On the bioautogram of exometabolites, we found two most pronounced zones (Rf 0.18 and 0.29) of Fusarium oxysporum var. orthoceras BZR P1 growth inhibition (fungicide). Zones with Rf 0.58 for B. velezensis BZR 336g and Rf 0.70 for B. velezensis BZR 517 correspond to the test fungus growth retardation (fungistatic). Significant suppression of Alternaria sp. BZR P8 growth was also observed in two zones (Rf 0.18 and 0.29). The use of surfactin, iturin A, fengycin (Sigma-Aldrich®) in the TLC analysis made it possible to detect similar lipopeptides in the composition of metabolite complexes produced by the studied bacteria. It should be noted that the studied strains differed both in their ability to produce metabolites of different structure (can be found when analyzing chromatograms under ultraviolet light) and in their effect on phytopathogenic fungi in vitro. This may indicate possible differences in the mechanism of antagonistic activity of bacteria against phytopathogenic fungi. Thus, B. velezensis BZR 336g and B. velezensis BZR 517 produce a significant set of antifungal metabolites and can be used as strains to produce effective biofungicides.

ASSESSMENT OF SOME ABIOTIC FACTORS ON MICROBIAL BIOPRODUCTS USEFUL IN BIOCONTROL OF PHYTOPATHOGENS

2016 ◽  
Vol 5 (3) ◽  
pp. 799-803
Author(s):  
Sergiu Fendrihan ◽  
Sorina Dinu ◽  
Oana Alina Sicuia ◽  
Florica Constantinescu
Keyword(s):  
Abiotic Factors ◽  
Fungal Growth ◽  
Phytopathogenic Fungi ◽  
Antagonistic Activity ◽  
Antagonistic Effect ◽  
Limiting Factors ◽  
Multiplication Rate ◽  
Antifungal Metabolites ◽  
Ph Conditions

The environmental factors may influence the growth of microorganisms, by favoring their growth or slowing their multiplication rate and the synthesis of different metabolites. Parameters such as temperature, aeration, nutrients, pH or tolerance to NaCl can become limiting factors for microorganisms survival. Bacillus subtilis and related species can grow in variable pH conditions, maintaining the cytoplasmically pH in a relatively close range, stable to the synthesis of proteins and nucleic acids.The aim of this work was to assess the influence of some abiotic factors on the biocontrol activity of microbial bioproducts, based on beneficial strains from Bacillus sp.. The bioproducts were tested in vitro against soil borne fungi at different temperatures and pH conditions. The results showed that the antagonistic activity of the biopreparates, tested at 27°C and 25°C, against phytopathogenic fungi released antifungal metabolites which inhibited the fungal growth. Also, when different pH values were analyzed, the results reflected that at pH 5.5 and pH 8.5 the bioproducts maintained the same antagonistic effect as in the control variant (pH 7.0).

scholarly journals Screening new Trichoderma isolates for antagonistic activity against several phytopathogenic fungi, including Fusarium spp.

2020 ◽  
Vol 7 (3) ◽  
pp. 14-25
Author(s):  
H. M. Tkalenko ◽  
O. I. Borzykh ◽  
S. V. Horal ◽  
K. M. Barvas-Hremiakova ◽  
L. A. Janse
Keyword(s):  
Fusarium Solani ◽  
Root Rot ◽  
Submerged Culture ◽  
Fungal Species ◽  
Phytopathogenic Fungi ◽  
Antagonistic Activity ◽  
Barley Grain ◽  
Cladosporium Fulvum ◽  
Fusarium Spp ◽  
Trichoderma Isolates

Aims. To obtain and characterize new isolates of Trichoderma antagonistic to phytopathogenic fungi, including Fusarium spp., and 2) to determine their suitability for mass production under different cultivation conditions. Methods. Microbiological, cultural-morphological, statistical. Results. From plants affected by phytopathogenic fungi: cucumber (Cucumis sativus L.), tomato (Solanum lycopersicum L.), white cabbage (Brassica oleracea L.), winter wheat (Triticum aestivum L.), spring barley (Hordeum vulgare L.) in the Forest-Steppe of Ukraine (Kyiv re- gion) 11 new Trichoderma isolates were obtained. Preliminary, morphological determination allocated fi ve of them to T. viride (isolates CK, 165, 27, 49, 35), two of them to T. koningii (21, 64) and four of them to T. longibrachiatum (161, 162, 163, 164). All isolates showed moderate to high antagonistic activity towards 8 phytopathogenic fungal species (Fusarium oxysporum, Fusarium solani, Alternaria cucumerina, Colletotrichum phomoides, Botrytis cinerea, Trichothecium roseum, Penicillium sp., Cladosporium fulvum). In a dual culture experiment they showed generally similar or often higher activity to the above-mentioned fungi than the 8 control strains used in our study, belonging to T. viride (5 strains), T. koningii (2 strains) and T. harzianum (1 strain), which have been maintained since long time in our laboratory. The most active new isolate CK, (presumably) T. viride, showed comparable high activity towards all phytopathogenic fungi as compared to our most active control strain of T. viride, no. 23. The latter is the basis of a biocide Trichodermin, produced by biolaboratories of Ukraine, including the Institute of Plant Protection, NAAS, Kyiv. Chlamydospore production of all isolates and strains studied in submerged culture varied from 10 6 to 3 · 10 7 spores/ml, were T. viride isolates and strains were on the higher end. Isolates of ‘T. longibrachiatum’ did not produce chlamydospores in submerged culture. Upon superfi cial cultivation on barley grain, the strains and isolates of T. viride were also characterized by the highest production of spores (6 · 10 9 -9 · 10 9 spores/g) as compared to those of T. kon- ingii, T. harzianum (5.5 · 10 9 -6.8 · 10 9 spores/g) and T. longibrachiatum (1.3 · 10 8 -6.8 · 10 8 spores/g). In an in-vivo experiment under laboratory conditions the most promising antagonistic isolate CK was used to inoculate wheat seed and tested for protection against Fusarium root rot (inoculum a mixture of F. avenaceum, F. culmorum, F. gibbosum, F. oxysporum, in 4·10 4 spores/g), where it gave an 83 % reduction in root rot as compared to the non-inoculated con- trol. Conclusions. Five new isolates preliminarily (on the basis of morphological characteristics only) allocated to T. viride and four to T. longibrachiatum demonstrated in vitro the highest and widest antagonistic activity against the phytopathogenic fungal species Fusarium oxysporum, Fusarium solani, Alternaria cucumerina, Colletotrichum pho- moides, Botrytis cinerea, Trichothecium roseum, Penicillium sp., Cladosporium fulvum, as compared to new isolates, preliminarily allocated to - T. harzianum and T. koningii. New isolate CK (allocated to T. viride) showed a promising and similar high antagonistic activity as compared to our T. viride 23 strain, which is already successfully used in the biocide Trichodermin. Since this isolate CK also produced a high number of chlamydospores in submerged culture (3 · 10 7 spores/ml) and conidia (8 · 10 9 spores/g) when surface cultured on barley grain respectively, it is a potential new candidate for a biocide. When this CK isolate was studied in a small laboratory pot experiment, to control Fu- sarium root rot in wheat by preventive seed inoculation, it caused an 83 % reduction in this Fusarium root rot. Its usefulness under fi eld conditions and its effect on growth of plants will be investigated in future research

scholarly journals Zinc Improves Biocontrol of Fusarium Crown and Root Rot of Tomato by Pseudomonas fluorescens and Represses the Production of Pathogen Metabolites Inhibitory to Bacterial Antibiotic Biosynthesis

1997 ◽  
Vol 87 (12) ◽  
pp. 1250-1257 ◽  
Author(s):  
Brion K. Duffy ◽  
Geneviève Défago
Keyword(s):  
Pseudomonas Fluorescens ◽  
Root Rot ◽  
Acid Production ◽  
Biocontrol Agent ◽  
Fusaric Acid ◽  
Antibiotic Biosynthesis ◽  
Production Of Hydrogen ◽  
Biocontrol Activity ◽  
Crown And Root Rot

Crown and root rot of tomato caused by Fusarium oxysporum f. sp. radicis-lycopersici is an increasing problem in Europe, Israel, Japan, and North America. The biocontrol agent Pseudomonas fluorescens strain CHA0 provides only moderate control of this disease. A one-time amendment of zinc EDTA at 33 μg of Zn2+/ml to hydroponic nutrient solution in soilless rockwool culture did not reduce disease when used alone, but did reduce disease by 25% in the presence of CHA0. In in vitro studies with the pathogen, zinc at concentrations as low as 10 μg/ml abolished production of the phytotoxin fusaric acid, a Fusarium pathogenicity factor, and increased production of microconidia over 100-fold, but reduced total biomass. Copper EDTA at 33 μg of Cu2+/ml had a similar effect as zinc on the pathogen in vitro; it reduced disease when used alone, and increased the biocontrol activity of CHA0 in soilless culture. Ammonium-molybdate neither improved the biocontrol activity of CHA0 nor affected production of fusaric acid or microconidia. Strain CHA0 did not degrade fusaric acid. Fusaric acid at concentrations as low as 0.12 μg/ml repressed production by CHA0 of the antibiotic 2,4-diacetylphloroglucinol, a key factor in the biocontrol activity of this strain. Production of pyoluteorin by CHA0 was also reduced, but production of hydrogen cyanide and protease was not affected, suggesting that fusaric acid affects biosynthesis at a regulatory level downstream of gacA and apdA genes. Fusaric acid did not affect the recovery of preformed antibiotics nor did it affect bacterial growth even at concentrations as high as 200 μg/ml. When microbial meta-bolite production was measured in the rockwool bioassay, zinc amendments reduced fusaric acid production and enhanced 2,4-diacetylphloro-glucinol production. We suggest that zinc, which did not alleviate the repression of antibiotic biosynthesis by fusaric acid, improved biocontrol activity by reducing fusaric acid production by the pathogen, which resulted in increased antibiotic production by the biocontrol agent. This demonstrates that pathogens can have a direct negative impact on the mechanism(s) of biocontrol agents.

scholarly journals Biocontrol by Phenazine-1-carboxamide-Producing Pseudomonas chlororaphis PCL1391 of Tomato Root Rot Caused by Fusarium oxysporum f. sp. radicis-lycopersici

1998 ◽  
Vol 11 (11) ◽  
pp. 1069-1077 ◽  
Author(s):  
Thomas F. C. Chin-A-Woeng ◽  
Guido V. Bloemberg ◽  
Arjan J. van der Bij ◽  
Koen M. G. M. van der Drift ◽  
Jan Schripsema ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Fusarium Oxysporum ◽  
Root Rot ◽  
Test System ◽  
Pseudomonas Chlororaphis ◽  
Tomato Root ◽  
Hydrophobic Compound ◽  
Biocontrol Activity ◽  
In Vitro Antifungal Activity

Seventy bacterial isolates from the rhizosphere of tomato were screened for antagonistic activity against the tomato foot and root rot-causing fungal pathogen Fusarium oxysporum f. sp. radicis-lycopersici. One isolate, strain PCL1391, appeared to be an efficient colonizer of tomato roots and an excellent biocontrol strain in an F. oxysporum/tomato test system. Strain PCL1391 was identified as Pseudomonas chlororaphis and further characterization showed that it produces a broad spectrum of antifungal factors (AFFs), including a hydrophobic compound, hydrogen cyanide, chitinase(s), and protease(s). Through mass spectrometry and nuclear magnetic resonance, the hydrophobic compound was identified as phenazine-1-carboxamide (PCN). We have studied the production and action of this AFF both in vitro and in vivo. Using a PCL1391 transposon mutant, with a lux reporter gene inserted in the phenazine biosynthetic operon (phz), we showed that this phenazine biosynthetic mutant was substantially decreased in both in vitro antifungal activity and biocontrol activity. Moreover, with the same mutant it was shown that the phz biosynthetic operon is expressed in the tomato rhizosphere. Comparison of the biocontrol activity of the PCN-producing strain PCL1391 with those of phenazine-1-carboxylic acid (PCA)-producing strains P. fluorescens 2-79 and P. aureofaciens 30-84 showed that the PCN-producing strain is able to suppress disease in the tomato/F. oxysporum system, whereas the PCA-producing strains are not. Comparison of in vitro antifungal activity of PCN and PCA showed that the antifungal activity of PCN was at least 10 times higher at neutral pH, suggesting that this may contribute to the superior biocontrol performance of strain PCL1391 in the tomato/F. oxysporum system.

scholarly journals In-vitro compatibility assay of indigenous Trichoderma and Pseudomonas species and their antagonistic activities against black root rot disease (Fusarium solani) of faba bean (Vicia faba L.)

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Alemayehu Dugassa ◽  
Tesfaye Alemu ◽  
Yitbarek Woldehawariat
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Pseudomonas Fluorescens ◽  
Faba Bean ◽  
Fusarium Solani ◽  
Root Rot ◽  
Mycelial Growth ◽  
Biocontrol Agents ◽  
Black Root Rot ◽  
Root Rot Disease ◽  
Rot Disease

Abstract Background Faba bean (Vicia faba L.) cultivation is highly challenged by faba bean black root rot disease (Fusarium solani) in high lands of Ethiopia. To ensure sustainable production of faba beans, searching for eco-friendly disease management options is necessary to curb the progress of the disease timely. The indigenous biocontrol agents that suit local environments may effectively strive with in-situ microorganisms and suppress local pathogen strains. This study aimed to screen antagonistic indigenous compatible Trichoderma and Pseudomonas strains against Fusarium solani. In the pathogenicity test, soil-filled pots were arranged in complete random block design and sown with health faba bean seeds. The effect of some fungicides was evaluated against Fusarium by food poisoning methods to compare with the biocontrol agents. The antagonistic efficacy of biocontrol agents and their compatibility was investigated on Potato dextrose agar medium. Results Fusarium solani AAUF51 strain caused an intense root rotting in faba bean plant. The effect of Mancozeb 80% WP at 300 ppm was comparable with Trichoderma and Pseudomonas strains against Fusarium. The mycelial growth of test the pathogen was significantly (P ≤ 0.05) reduced to 86.67 and 85.19% by Trichoderma harzianum AAUW1 and Trichoderma viridae AAUC22 strains in dual culture, respectively. The volatile metabolites of Pseudomonas aeruginosa AAUS31 (77.78%) found the most efficient in reducing mycelial growth of Fusarium followed by Pseudomonas fluorescens AAUPF62 (71.11%) strains. The cell-free culture filtrates of Pseudomonas fluorescens AAUPF62 and Pseudomonas aeruginosa AAUS31 were more efficient than the Trichoderma strain in reducing the growth of Fusarium isolates. There was no zone of inhibition recorded between Trichoderma harzianum AAUW1, Trichoderma viridae AAUC22, Pseudomonas aeruginosa AAUS31, and Pseudomonas fluorescens AAUPF62 strains, hence they were mutually compatible. Conclusions The compatible Trichoderma and Pseudomonas strains showed antagonistic potentiality that could be explored for faba bean protection against black root rot disease and might have a future dual application as biocontrol agents.

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