scholarly journals Effect of agitation rate on the production of antifungal metabolites by Streptomyces hygroscopicus in a lab-scale bioreactor

2017 ◽  
pp. 231-244 ◽  
Author(s):  
Ivana Mitrovic ◽  
Jovana Grahovac ◽  
Jelena Dodic ◽  
Mila Grahovac ◽  
Sinisa Dodic ◽  
...  
Keyword(s):  
Inhibition Zone ◽  
Phytopathogenic Fungi ◽  
Plant Diseases ◽  
Streptomyces Hygroscopicus ◽  
Agitation Rate ◽  
Promising Alternative ◽  
Potato Dextrose Agar Medium ◽  
Antifungal Metabolites ◽  
Apple Fruits

The application of antifungal compounds produced by microorganisms in the control of plant diseases caused by phytopathogenic fungi is a promising alternative to synthetic pesticides. Among phytopathogenic fungi, Alternaria alternata and Fusarium avenaceum are significant pathogens responsible for the storage rot of apple fruits. During storage, transport and marketing A. alternata and F. avenaceum can cause significant losses of apple fruits and their control is of great importance for the producers and consumers. In the present study, the effects of agitation rate on the production of antifungal methabolite( s) by Streptomyces hygroscopicus in a 3-L lab-scale bioreactor (Biostat? Aplus, Sartorius AG, Germany) against two isolates of A. alternata and two isolates of F. avenaceum were investigated. The cultivation of S. hygroscopicus was carried out at 27?C with agitation rates of 100 rpm and 200 rpm during 7 days. The aim was to analyze the bioprocess parameters of biofungicide production in a medium containing glycerol as a carbon source, and examine the effect of agitation rate on the production of antifungal metabolite(s). The in vitro antifungal activity of the produced metabolites against fungi from the genera Alternaria and Fusarium grown on potato dextrose agar medium was determined every 24 h using wells technique. In the experiments conducted in the bioreactor at different stirring speeds, it was found that the maximum production of antifungal metabolites occurred after 96 hours of cultivation. A higher consumption of nutrients and a larger inhibition zone diameter was registered in the experiment with an agitation rate of 200 rpm.

scholarly journals Effect of nitrogen sources on the production of antifungal metabolites by Streptomyces hygroscopicus

2017 ◽  
pp. 183-191
Author(s):  
Ivana Mitrovic ◽  
Jovana Grahovac ◽  
Jelena Dodic ◽  
Sinisa Dodic ◽  
Mila Grahovac
Keyword(s):  
Nitrogen Source ◽  
Fusarium Species ◽  
Nitrogen Sources ◽  
Medium Composition ◽  
Plant Diseases ◽  
Diffusion Method ◽  
Antifungal Compounds ◽  
Promising Alternative ◽  
Antifungal Metabolites

Biotechnologically produced antifungal compounds for control of plant diseases caused by phytopathogenic fungi represent a promising alternative to synthetic pesticides. Fungi from the genera Alternaria and Fusarium are listed among important storage pathogens of apple fruits. A. alternata causes significant annual losses of apple fruit. Also, F. avenaceum is one of the most commonly encountered Fusarium species identified as the causal agent of a wet apple core rot. Species of the Streptomyces genera are soil bacteria that produce significant quantities of bioactive compounds in appropriate media. Defining the culture medium composition is the basis of bioprocesses development. Nitrogen source is critical component of cultivation medium and also the most useful tool for stimulation of the antifungal metabolites production. The aim of this study was to select the best nitrogen sources in medium for the production of antifungal compounds effective against A. alternata and F. avenaceum by S. hygroscopicus. Activity of the cultivation liquids on A. alternata and F. avenaceum isolates was tested in vitro using well diffusion method. The results in?dicate that maximum inhibition zone was reached in medium with soybean meal as nitrogen source with inhibition diameter more than 35 mm for both tested fungi.

scholarly journals Production of plant protection agents in medium containing waste glycerol by Streptomyces hygroscopicus: Bioprocess analysis

2020 ◽  
Vol 49 (3) ◽  
pp. 270-277
Author(s):  
I. Mitrović ◽  
J. Grahovac ◽  
J. Dodić ◽  
A. Jokić ◽  
Z. Rončević ◽  
...  
Keyword(s):  
Plant Protection ◽  
Phytopathogenic Fungi ◽  
Global Market ◽  
Biodiesel Production ◽  
Streptomyces Hygroscopicus ◽  
Diffusion Method ◽  
Agitation Rate ◽  
Antifungal Metabolites ◽  
Waste Glycerol ◽  
Fruit Samples

The surplus of waste glycerol, by-product of the biodiesel production process, is available at the global market. Some species of the genera Streptomyces have the ability to assimilate glycerol and convert it into valuable metabolic products. In the present study, the ability of Streptomyces hygroscopicus to assimilate waste glycerol and convert it into metabolic compounds with antifungal activity against four phytopathogenic fungi obtained from apple fruit samples expressing rot symptoms, was investigated. Production of antifungal metabolites by S. hygroscopicus was carried out in 3 l stirred tank bioreactor through 7 days. Fermentation was carried out at 27 °C with aeration rate of 1.5 vvm and agitation rate of 100 r.p.m. The aim of this work was to analyse bioprocess parameters and to determine at which stage of bioprocess the production of antifungal metabolites occurs. Activity of the cultivation liquid on two isolates of Alternaria alternata and two isolates of Fusarium avenaceum were determined every 12 h using in vitro well diffusion method. It was found that the maximum production of antifungal metabolites occurred at 108 hour of cultivation. Formed inhibition zones have shown that the produced antifungal metabolites have high efficacy on tested phytopathogenic fungi (inhibition zone diameter higher than 35 mm for all test organisms).

scholarly journals A Metabolomic Study of Epichloë Endophytes for Screening Antifungal Metabolites

Metabolites ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 37
Author(s):  
Krishni Fernando ◽  
Priyanka Reddy ◽  
Kathryn M. Guthridge ◽  
German C. Spangenberg ◽  
Simone J. Rochfort
Keyword(s):  
Phytopathogenic Fungi ◽  
Bioactive Metabolites ◽  
Symbiotic Association ◽  
In Planta ◽  
Vitro Assay ◽  
Antifungal Metabolites ◽  
Bioassay Guided Fractionation ◽  
Toxic Alkaloids ◽  
Epichloë Endophytes

Epichloë endophytes, fungal endosymbionts of Pooidae grasses, are commonly utilized in forage and turf industries because they produce beneficial metabolites that enhance resistance against environmental stressors such as insect feeding and disease caused by phytopathogen infection. In pastoral agriculture, phytopathogenic diseases impact both pasture quality and animal production. Recently, bioactive endophyte strains have been reported to secrete compounds that significantly inhibit the growth of phytopathogenic fungi in vitro. A screen of previously described Epichloë-produced antifeedant and toxic alkaloids determined that the antifungal bioactivity observed is not due to the production of these known metabolites, and so there is a need for methods to identify new bioactive metabolites. The process described here is applicable more generally for the identification of antifungals in new endophytes. This study aims to characterize the fungicidal potential of novel, ‘animal friendly’ Epichloë endophyte strains NEA12 and NEA23 that exhibit strong antifungal activity using an in vitro assay. Bioassay-guided fractionation, followed by metabolite analysis, identified 61 metabolites that, either singly or in combination, are responsible for the observed bioactivity. Analysis of the perennial ryegrass-endophyte symbiota confirmed that NEA12 and NEA23 produce the prospective antifungal metabolites in symbiotic association and thus are candidates for compounds that promote disease resistance in planta. The “known unknown” suite of antifungal metabolites identified in this study are potential biomarkers for the selection of strains that enhance pasture and turf production through better disease control.

Role of chitinase and β-1,3-glucanase activities produced by a fluorescent pseudomonad and in vitro inhibition of Phytophthora capsici and Rhizoctonia solani

2007 ◽  
Vol 53 (2) ◽  
pp. 207-212 ◽  
Author(s):  
Naveen Kumar Arora ◽  
Min Jeong Kim ◽  
Sun Chul Kang ◽  
Dinesh Kumar Maheshwari
Keyword(s):  
Rhizoctonia Solani ◽  
Phytophthora Capsici ◽  
Phytopathogenic Fungi ◽  
Culture Technique ◽  
Dual Culture ◽  
Fluorescent Pseudomonad ◽  
Antifungal Metabolites ◽  
Fluorescent Pseudomonas

A study was conducted to investigate the possibility of involvement of chitinase and β-1,3-glucanase of an antagonistic fluorescent Pseudomonas in growth suppression of phytopathogenic fungi, Phytophthora capsici and Rhizoctonia solani . Fluorescent Pseudomonas isolates GRC3 and GRC4 were screened for their antifungal potential against phytopathogenic fungi by using dual culture technique both on solid and liquid media. The percent inhibition was calculated. Various parameters were monitored for optimization of enzyme activities by fluorescent Pseudomonas GRC3. The involvement of chitinases, β-1,3-glucanases, and antifungal metabolites of nonenzymatic nature was correlated with the inhibition of P. capsici and R. solani. The results provide evidence for antibiosis as a mechanism for antagonism. The study also confirms that multiple mechanisms are involved in suppressing phytopathogens as evidenced by the involvement of chitinase and β-1,3-glucanase in inhibition of R. solani but not P. capsici by isolate GRC3.

scholarly journals In vitro study of baseline sensitivity of important fungi against different fungicides

2012 ◽  
Vol 4 (2) ◽  
pp. 264-265 ◽  
Author(s):  
Sanjay Goswami ◽  
R. Kaur ◽  
Dipak T. Nagrale
Keyword(s):  
Botrytis Cinerea ◽  
Alternaria Alternata ◽  
In Vitro Study ◽  
Phytopathogenic Fungi ◽  
Plant Diseases ◽  
Baseline Sensitivity ◽  
Resistance Development ◽  
Gloeosporium Ampelophagum ◽  
Mic Value

Baseline sensitivity values of important phytopathogenic fungi were studied against fungicides. ED50, ED90 and MIC value of propiconazole for, Colletotrichum capsici, and Gloeosporium ampelophagum was in the range of 0.020-0.04 μg/ml. ED50 values of tebuconazole for Alternaria alternata was 30.0 μg/ml. Azoxystrobin was also tested for its ED50, ED90 and MIC values against Alternaria alternata, C. capsici, G. ampelophagum and Botrytis cinerea where the values were in the range of 0.019-50.0, 0.03-60.0 and 0.2-100.0 μg/ml respectively. Baseline sensitivity values are important for the management of plant diseases and resistance development.

scholarly journals Optimization of medium composition for the production of compounds effective against Xanthomonas campestris by bacillus subtilis

2014 ◽  
pp. 247-258 ◽  
Author(s):  
Zorana Roncevic ◽  
Jovana Grahovac ◽  
Damjan Vucurovic ◽  
Sinisa Dodic ◽  
Bojana Bajic ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Sodium Nitrite ◽  
Xanthomonas Campestris ◽  
Inhibition Zone ◽  
Medium Composition ◽  
Plant Diseases ◽  
Antimicrobial Compounds ◽  
Promising Alternative ◽  
Inhibition Zone Diameter ◽  
Zone Diameter

The biocontrol agents are a very promising alternative to synthetic pesticides that are presently used to control plant diseases caused by phytopathogenic microorganisms. Members of the Bacillus genera are soil bacteria that produce significant quantities of agriculturally important bioactive compounds. Production of these compounds can be improved by changing the nutritional and environmental conditions. The aim of this study was the optimization of medium composition, using response surface methodology, for the production of compounds effective against Xanthomonas campestris ATCC 13951 by Bacillus subtilis ATCC 6633. To study the production of antimicrobial compounds by selected Bacillus strain, the producing microorganisms were cultivated on nutrient broth. The inhibition zone diameter of 18.0 mm obtained by the diffusion-disc method indicated that the used Bacillus subtilis strain produces compounds with antimicrobial activity against Xanthomonas campestris ATCC 13951. To optimize the composition of the cultivation medium in terms of glycerol, sodium nitrite and phosphates content, experiments were carried out in accordance with Box-Behnken design, and optimization of multiple responses was performed using the concept of desirability function. The developed model predicted that the maximum inhibition zone diameter (26.23 mm) against tested phytopathogen is achieved when the initial content of glycerol, sodium nitrite and phosphate were 50.00 g/L, 2.85 g/L and 11.00 g/L, respectively. To minimize the consumption of medium components and costs of effluents processing, additional optimization set was made. The techno-economic analysis of the obtained results has to be done to select optimal medium composition for industrial production of antimicrobial compounds.

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.

scholarly journals Antifungal Secondary Metabolites Produced by the Fungal Endophytes: Chemical Diversity and Potential Use in the Development of Biopesticides

2021 ◽  
Vol 12 ◽  
Author(s):  
Kuo Xu ◽  
Xiu-Qi Li ◽  
Dong-Lin Zhao ◽  
Peng Zhang
Keyword(s):  
Natural Products ◽  
Crop Production ◽  
Fungal Endophytes ◽  
Phytopathogenic Fungi ◽  
Chemical Diversity ◽  
Plant Diseases ◽  
Chemical Examination ◽  
Global Food Security ◽  
Antifungal Metabolites ◽  
Potential Use

Plant diseases caused by phytopathogenic fungi can lead to huge losses in the agricultural fields and therefore remain a continuous threat to the global food security. Chemical-based fungicides contributed significantly in securing crop production. However, indiscriminate application of fungicides has led to increased chemical resistance and potential risks to human health and environment. Thus, there is an urgent need for searching for new bioactive natural products and developing them into new biopesticides. Fungal endophytes, microorganisms that reside in the fresh tissues of living plants, are regarded as untapped sources of novel natural products for exploitation in agriculture and/or medicine. Chemical examination of endophytic fungi has yielded enormous antifungal natural products with potential use in the development of biopesticides. This review summarizes a total of 132 antifungal metabolites isolated from fungal endophytes in the past two decades. The emphasis is on the unique chemical diversity of these metabolic products, together with their relevant antifungal properties. Moreover, some “star molecules,” such as griseofulvin and trichothecene, as well as their synthetic derivatives that possess high potential as candidates of new natural fungicides, are also presented herein.

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 Activity of Anthracenediones and Flavoring Phenols in Hydromethanolic Extracts of Rubia tinctorum against Grapevine Phytopathogenic Fungi

Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1527
Author(s):  
Natalia Langa-Lomba ◽  
Eva Sánchez-Hernández ◽  
Laura Buzón-Durán ◽  
Vicente González-García ◽  
José Casanova-Gascón ◽  
...  
Keyword(s):  
Fungal Species ◽  
Phytopathogenic Fungi ◽  
Ex Situ ◽  
Antifungal Compound ◽  
Promising Alternative ◽  
Grapevine Trunk Diseases ◽  
Rubia Tinctorum ◽  
Botryosphaeria Dieback ◽  
Trunk Diseases

In this work, the chemical composition of Rubia tinctorum root hydromethanolic extract was analyzed by GC–MS, and over 50 constituents were identified. The main phytochemicals were alizarin-related anthraquinones and flavoring phenol compounds. The antifungal activity of this extract, alone and in combination with chitosan oligomers (COS) or with stevioside, was evaluated against the pathogenic taxa Diplodia seriata, Dothiorella viticola and Neofusicoccum parvum, responsible for the so-called Botryosphaeria dieback of grapevine. In vitro mycelial growth inhibition tests showed remarkable activity for the pure extract, with EC50 and EC90 values as low as 66 and 88 μg·mL−1, respectively. Nonetheless, enhanced activity was attained upon the formation of conjugate complexes with COS or with stevioside, with synergy factors of up to 5.4 and 3.3, respectively, resulting in EC50 and EC90 values as low as 22 and 56 μg·mL−1, respectively. The conjugate with the best performance (COS–R. tinctorum extract) was then assayed ex situ on autoclaved grapevine wood against D. seriata, confirming its antifungal behavior on this plant material. Finally, the same conjugate was evaluated in greenhouse assays on grafted grapevine plants artificially inoculated with the three aforementioned fungal species, resulting in a significant reduction in the infection rate in all cases. This natural antifungal compound represents a promising alternative for developing sustainable control methods against grapevine trunk diseases.

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