Europe PMC

This website requires cookies, and the limited processing of your personal data in order to function. By using the site you are agreeing to this as outlined in our privacy notice and cookie policy.

Bioactive antifungal metabolites produced by Streptomyces amritsarensis V31 help to control diverse phytopathogenic fungi.

Author information

Affiliations

  • 1. Microbial Technology Unit II, ICAR-National Bureau of Agriculturally Important Microorganisms (NBAIM), Uttar Pradesh, Kushmaur, Mau, 275103, India.
      Authors
    • Shahid M 1
    • Singh BN 1
    • Verma S 1
    • Choudhary P 1
    • Das S 1
    • Chakdar H 1
    • Murugan K 1
    • Goswami SK 1
    • Saxena AK 1
    (9 authors)

ORCIDs linked to this article

Brazilian Journal of Microbiology : [publication of the Brazilian Society for Microbiology], 30 Sep 2021, 52(4):1687-1699
https://doi.org/10.1007/s42770-021-00625-w PMID: 34591293 PMCID: PMC8578481

Free full text in Europe PMC

Abstract 

Actinomycetes due to their unique repertoire of antimicrobial secondary metabolites can be an eco-friendly and sustainable alternative to agrochemicals to control plant pathogens. In the present study, antifungal activity of twenty different actinomycetes was evaluated via dual culture plate assay against six different phytopathogens, viz., Alternaria alternata, Aspergillus flavus, Fusarium oxysporum f. sp. lycopersici, Sarocladium oryzae, Sclerotinia sclerotiorum, and Rhizoctonia solani. Two potential isolates, Streptomyces amritsarensis V31 and Kribella karoonensis MSCA185 showing high antifungal activity against all six fungal pathogens, were further evaluated after extraction of bioactive metabolites in different solvents. Metabolite extracted from S. amritsarensis V31 in different solvents inhibited Rhizoctonia solani (7.5-65%), Alternaria alternata (5.5-52.7%), Aspergillus flavus (8-30.7%), Fusarium oxysporum f. sp. lycopersici (25-44%), Sarocladium oryzae (11-55.5%), and Sclerotinia sclerotiorum (29.7-40.5%); 1000 D diluted methanolic extract of S. amritsarensis V31 showed growth inhibition against R. solani (23.3%), A. flavus (7.7%), F. oxysporum (22.2%), S. oryzae (16.7%), and S. sclerotiorum (19.0%). Metabolite extracts of S. amritsarensis V31 significantly reduced the incidence of rice sheath blight both as preventive and curative sprays. Chemical profiling of the metabolites in DMSO extract of S. amritsarensis V31 revealed 6-amino-5-nitrosopyrimidine-2,4-diol as the predominant compound present. It was evident from the LC-MS analyses that S. amritsarensis V31 produced a mixture of potential antifungal compounds which inhibited the growth of different phytopathogenic fungi. The results of this study indicated that metabolite extracts of S. amritsarensis V31 can be exploited as a bio-fungicide to control phytopathogenic fungi.

Free full text 

Logo of brazjmicroLink to Publisher's site
Braz J Microbiol. 2021 Dec; 52(4): 1687–1699.
Published online 2021 Sep 30. https://doi.org/10.1007/s42770-021-00625-w
PMCID: PMC8578481
PMID: 34591293

Bioactive antifungal metabolites produced by Streptomyces amritsarensis V31 help to control diverse phytopathogenic fungi

Mohammad Shahid,1 Bansh Narayan Singh,1 Shaloo Verma,1 Prassan Choudhary,1 Sudipta Das,1 Hillol Chakdar,corresponding author1 Kumar Murugan,1 Sanjay Kumar Goswami,1,2 and Anil Kumar Saxena1
Author information Article notes Copyright and License information Disclaimer

Associated Data

Supplementary Materials
Data Availability Statement

Abstract

Actinomycetes due to their unique repertoire of antimicrobial secondary metabolites can be an eco-friendly and sustainable alternative to agrochemicals to control plant pathogens. In the present study, antifungal activity of twenty different actinomycetes was evaluated via dual culture plate assay against six different phytopathogens, viz., Alternaria alternata, Aspergillus flavus, Fusarium oxysporum f. sp. lycopersici, Sarocladium oryzae, Sclerotinia sclerotiorum, and Rhizoctonia solani. Two potential isolates, Streptomyces amritsarensis V31 and Kribella karoonensis MSCA185 showing high antifungal activity against all six fungal pathogens, were further evaluated after extraction of bioactive metabolites in different solvents. Metabolite extracted from S. amritsarensis V31 in different solvents inhibited Rhizoctonia solani (7.5–65%), Alternaria alternata (5.5–52.7%), Aspergillus flavus (8–30.7%), Fusarium oxysporum f. sp. lycopersici (25–44%), Sarocladium oryzae (11–55.5%), and Sclerotinia sclerotiorum (29.7–40.5%); 1000 D diluted methanolic extract of S. amritsarensis V31 showed growth inhibition against R. solani (23.3%), A. flavus (7.7%), F. oxysporum (22.2%), S. oryzae (16.7%), and S. sclerotiorum (19.0%). Metabolite extracts of S. amritsarensis V31 significantly reduced the incidence of rice sheath blight both as preventive and curative sprays. Chemical profiling of the metabolites in DMSO extract of S. amritsarensis V31 revealed 6-amino-5-nitrosopyrimidine-2,4-diol as the predominant compound present. It was evident from the LC–MS analyses that S. amritsarensis V31 produced a mixture of potential antifungal compounds which inhibited the growth of different phytopathogenic fungi. The results of this study indicated that metabolite extracts of S. amritsarensis V31 can be exploited as a bio-fungicide to control phytopathogenic fungi.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42770-021-00625-w.

Keywords: Actinomycetes, Fungal phytopathogens, Rice sheath blight, Antifungal metabolites, Biocontrol, LC–MS

Introduction

Plant diseases have always been a potential threat to crop growth and production worldwide. Diseases can affect plants by interfering physiological processes in many ways such as photosynthesis, cell division, translocation of water, and plant growth and development. It is estimated that approximately 12.5% crop losses occur globally due to these phytopathogens. The fungi are the most destructive among all phytopathogens which can cause about 65% loss of plant host species [1]. According to FAOSTAT1, fungi affected most of the economically important crops globally (www.fao.org). Under the present climate change scenario, incidences of several fungal diseases have escalated [2]. Therefore, management of these fungal diseases is very crucial to safeguard a constant supply of food to the increasing world population.

To control the fungal diseases, a number of agrochemicals including synthetic fungicides are applied widely and repeatedly [3]. However, the indiscriminate use of such agrochemicals has caused serious problems like ground water pollution, ecological imbalances in soil systems, and health concerns in human beings [4, 5]. So, to overcome the use of chemical fungicides, there is an urgent need to explore a cheap, economical, and ecologically sustainable choice to minimize the risks associated with these chemicals. In this context, several actinomycetes having antagonistic properties against fungal pathogens due to their excellent metabolic diversity can be a potential and promising option.

Actinomycetes are best parsimoniously and biotechnologically valuable prokaryotes ranking a noticeable position due to their heterogeneous diversity and ability to produce novel antibiotics [6], antifungal metabolites [7], and extracellular enzymes [8]. Additionally, there are reports that actinomycetes isolated from various rhizosphere soils produce plant growth promoting active biomolecules such as iron chelators, i.e., siderophores [9], phytohormones [10], and organic acids [11].

A number of soil actinomycetes, mostly those related to the genus of Streptomyces, are reported as antifungal agents which can inhibit or suppress the growth of phytopathogenic fungi [12, 13]. Besides these, several species of actinomycetes are well known for their antibacterial [14], antitumor [15], antiviral [16], and nematicidal activities [17]. The mechanisms behind all these activities include release of hydrolytic enzymes, competition, and production of antibiotics as well as cyanogenic compounds. Volatile organic compounds (VOCs) having robust antifungal activity are produced by a number of actinomycetes species such as Streptomyces [18], Micromonospora [19], and Arthrobacter [20] and are effective against several phytopathogenic fungi.

In the present study, we have evaluated the antifungal activity of actinomycetes belonging to twelve different genera followed by characterization of antifungal metabolites through mass spectrometry and evaluation of selected actinomycetes for their potential to control sheath blight of rice.

Materials and methods

Actinomycetes cultures

Twenty different actinomycetes belonging to twelve different genera were procured from the National Agriculturally Important Microbial Culture Collection (NAIMCC), ICAR-NBAIM, India (Table ​(Table1).1). All the actinomycetes were revived on Nutrient Agar media (HiMedia, India) and incubated at 30 °C for 3–5 days for growth. These actinomycetes were maintained on nutrient agar plates during the experiments conducted.

Table 1

Actinomycetes cultures used in the study

Sl. NoCulturesNAIMCC accession no.Geographical locationGeographical coordinates
1Pseudarthrobacter niigatensis MJM11NAIMCC-B-02338Nongkhlaw, Meghalaya, IndiaN 25°41.450′ and E 91°38.529
2Kitasatospora paracochleata MJM69NAIMCC-B-02335Shallang, Meghalaya, IndiaN 25°32.183′ and E 90°51.355′
3P. chlorophenolius MSCA7NAIMCC-B-02334Umiam, Meghalaya, IndiaN 25°40.885′ and E 91°54.721′
4Amycolatopsis pretoriensis MSCA21NAIMCC-B-02336Umiam, Meghalaya, IndiaN 25°40.885′ and E 91°54.721′
5Micromonospora chalcea MSCA26NAIMCC-B-02341Umiam, Meghalaya, IndiaN 25°40.885′ and E 91°54.721′
6Saccharomonospora azurea MSCA47NAIMCC-B-02340Sohryngkham, Meghalaya, IndiaN 25°32.110′ and E 91°57.800′
7Nonomuraea wenchangensis MSCA53NAIMCC-B-02339Sohiong, Meghalaya, IndiaN 25°29.959′ and E 91°43.675′
8M. chalcea MSCA60NAIMCC-B-02337Sohiong, Meghalaya, IndiaN 25°29.959′ and E 91° 43.675′
9P. siccitolerans MSCA72NAIMCC-B-02333Jowai, Meghalaya, IndiaN 25°27.249′ and E92°11.474
10Saccharopolyspora shandongensis MSCA89NAIMCC-B-02329Rongjeng, Meghalaya, IndiaN 25°38.409′ and E 90°48.368′
11P. siccitolerans MSCA102NAIMCC-B-02331Nongkhlaw, Meghalaya, IndiaN 25°41.450′ and E 91°38.529
12Brachybacterium rhamnosum MSCA105NAIMCC-B-02332Nongthymme, Meghalaya, IndiaN 25°37.214′ and E 92°16.085′
13Promicromonospora aerolata MSCA117NAIMCC-B-02330Langumsing, Meghalaya, IndiaN 25°37.705′ and E 91° 02.191′
14Kribbella karoonensis MSCA185NAIMCC-B-02695Umsaw, Meghalaya, IndiaN 25°34.274′ and E 91°12.675
15Microbacterium jejuense B2NAIMCC-B-02191Brahamanpur, Mau, U.P., IndiaN 25°33.192′ and E 82°57.279′
16Microbacterium ginsengiterrae C6NAIMCC-B-02198Choja Khas, Mau, U.P., IndiaN 25° 45.428′ and E 83°22.461′
17Streptomyces luridiscabiei A17NAIMCC-B-02177Valley of Flowers, Chamoli, Uttarakhand, IndiaN 30°43.562′ and E 79°35.498′
18S. harbinensis A13NAIMCC-B-02178Valley of Flowers, Chamoli, Uttarakhand, IndiaN 30°43.562′ and E 79°35.498′
19S. amritsarensis V31NAIMCC-B-02174Valley of Flowers, Chamoli, Uttarakhand, IndiaN 30°43.562′ and E 79°35.498′
20S. amritsarensis V49NAIMCC-B-02161Valley of Flowers, Chamoli, Uttarakhand, IndiaN 30°43.562′ and E 79°35.498′

Phytopathogenic fungi

Six different phytopathogenic fungi, viz. Rhizoctonia solani (NAIMCC-F-03220), Alternaria alternata (NAIMCC-F-00067), Aspergillus flavus (NAIMCC-F-02905), Fusarium oxysporum f. sp. lycopersici (NAIMCC-F-00889), Sarocladium oryzae (NAIMCC-F-01633), and Sclerotinia sclerotiorum (NAIMCC-F-03341) were procured from NAIMCC, ICAR-NBAIM, Maunath Bhanjan, UP, India. All fungal cultures were revived in potato dextrose agar (PDA) medium (HiMedia, India) and incubated at 28 ± 2 °C for 1 week. All the fungal cultures were maintained on PDA slants and mineral oil for further use. Three- to five-days-old fungal plate cultures were used for antifungal assays.

In vitro antagonistic activity of actinomycetes against phytopathogenic fungi

Actinomycetes were evaluated for their antagonistic activities against six phytopathogenic fungi using dual culture plate assay [21]. Equal ratio of NA/PDA media was used for the assays. Fresh cultures of actinomycetes were streaked equi-distant from the center toward periphery on NA/PDA plates. Mycelium of freshly grown fungus (6 mm, dia) was placed at the center of the plate and incubated at 28 ± 2 °C for 2–3 days and observed regularly during incubation. Fungal strains grown without actinomycetes cultures were treated as a control. The growth inhibition of pathogens and percent inhibition of fungi were recorded using the radial growth of mycelium using the following equation modified from [22]

Zoneofinhibition=C-T
PI=[(Cs-T)/C]×100

where PI is the percent inhibition.

C=Cc-Cs

CC is the radius of radial fungal hyphae from the center (cm) without actinomycetes culture; Cs is the radius of radial fungal hyphae from the center (cm) with pure solvent; and T is the radius of radial fungal hyphae from the center (cm) with actinomycetes culture.

Preparation of crude extracts from actinomycetes

The production of metabolites was carried out by submerged fermentation using nutrient broth medium [23]. Five milliliters of freshly grown actinomycetes culture suspension was inoculated in 45 mL of nutrient broth medium and kept in a shaker with continuous agitation (120 rpm) at 37 °C for 3 days to prepare the mother inoculum. One-liter sterile nutrient broth was inoculated with 5% (v/v) inoculum and kept in a shaker with continuous agitation (140 rpm) at 37 °C for 12–14 days. Then the culture broth was collected and centrifuged at 8000 rpm for 20 min. Actinomycetes biomass were separately extracted with four solvent such as ethyl acetate (EA), dimethyl sulfoxide (DMSO), n-Hexane, and methanol (MeOH) using 1:3 (w/v) pellet:solvent ratio. All the solvents were of analytical grade and procured form HiMedia (India). The solvents were evaporated using rotary vacuum evaporator (Hahnvapor, Hahnshin, HS-2005S-N, Hahnshin S and T Co. Ltd., Korea), and dissolved in 2 mL of respective solvents.

Determination of antifungal activity of the crude and diluted extracts using well diffusion assay

Extracts obtained with different solvents along with crude cell free extracts were tested for their ability to inhibit the mycelial growth of the aforementioned phytopathogenic fungi using well diffusion assay as described previously [24]. All the fungi were sub-cultured on PDA medium and incubated at 28 ± 2 °C for 2 days. For the assays, a 6-mm disc of freshly grown fungus was placed at the center of sterile NA/PDA plates and incubated at 28 ± 2 °C for 2 days. Then the wells were made 1 cm away from the periphery of petri-dishes and sealed with 1% agar to prevent the leakage of solvents. Forty microliters of each of the solvent extracts, viz. 0, 10, 100, and 1000 D was placed in each well. A set of PDA petri-dishes containing only fungal pathogens alone and another set with wells containing only pure solvents were also kept for comparison. All the plates were incubated at 28 ± 2 °C for 3–4 days, and the data were recorded regularly during incubation. The inhibition of fungal growth was calculated as described in the “In vitro antagonistic activity of actinomycetes against phytopathogenic fungi” section.

Evaluation of the extracts for controlling sheath blight of rice under polyhouse conditions

Effect of extracts containing bioactive compounds from selected actinomycetes isolates was evaluated through pot trials with R. solani PU RS1 causing sheath blight of rice. The seeds of sheath blight susceptible rice cultivar (PB-1) were sown in plastic pots (12″ dia) filled with sterile field soil. The standard agronomic practices were followed to raise the plants. Sheath inoculation was done with 6-days-old sclerotium obtained from the culture of R. solani PU RS1 at boot stage (70 days old) of the rice plants. One sclerotium was inserted into the leaf sheath of the rice plant with the help of forceps and the inoculation point was wrapped with wet absorbent cotton. The plants were regularly sprayed with sterilized water to maintain the humidity.

Two parallel experiments with two types of sprays, viz. preventive (first spray of metabolites and then inoculation of pathogen) and curative (first inoculation of pathogen and then spray of metabolites) were carried out. In the experiment with preventive spray, 100 D extracts (EA, n-hexane, MeOH, and DMSO @ 2.0%) were sprayed with atomizer on 60-day-old rice plants, and after a day sclerotia (6 days old) of R. solani PU RS1 were placed in leaf sheath and wrapped with moist absorbent cotton. On the contrary, in the experiment with curative spray, infected plants (1 week post-inoculation) were sprayed with extracts (EA, n-hexane, MeOH, and DMSO @ 2.0%). Spraying of absolute solvents served as control. After 14 days of fungal inoculation, the lesion length (cm) was recorded [25]. Three replications for each treatment were used during the experiment. A completely randomized design (CRD) was followed to conduct the trial, and the experiment was repeated twice.

LC–MS analysis of methanolic extract from Streptomyces amritsarensis V31

LC–MS analysis was outsourced from Central Instrumentation Facility (CIF), University of Delhi, South Campus, New Delhi, India. Thermo Fisher Scientific Compound Discoverer 2.2 was used to analyze the metabolites present. The metabolite separation was performed by 25,003–052,130 Hypersil Gold C18 (2.1 mm × 50 mm, 3 µm) column with mobile phase containing 0.05% formic acid (FA) + water solution (A) and acetonitrile (ACN) (B). The linear elution gradient program was 0% B, maintained for 2.0 min, then increased to 100% B between 1 and 40.8 min, maintained for 2 min, increased to 100% B from 30 to 30.1 min, and held at 0% from 30.1 to 40.8 min. The volume of injection was 10 μL. The temperature of the column was 30 °C and the flow rate was 1 mL/min. Mass spectrometry detections were set as follows: capillary voltage of ( +) 4.0 and ( −) 3.3 kV and Probe Heater temperature at 330 °C. The full MS resolution was set to 140,000. The mass scan range was from 100 to 1500 m/z. The MS2 resolution was set to 35,000. The MS2 scan range was set between 200 and 2000 m/z. The processed data set was next subjected to molecular formula prediction and peak identification. For this purpose, mZCloud Advanced mass spectral database (https://www.mzcloud.org/) and Chemspider database (http://www.chemspider.com/) were used.

Statistical analysis

The data obtained from experiments were analyzed using one-way analysis of variance (ANOVA) through SPSS version 16. Treatments with significant level were further analyzed by Duncan’s multiple range test (DMRT) at p < 0.05. The data were represented as mean ± standard deviation. Different letters present on the bars show significant differences between two mean values.

Results

Antifungal activity of actinomycetes on the fungi

Antifungal activities of the twenty different actinomycetes against six different phytopathogens like R. solani, A. alternata, A. flavus, F. oxysporum f. sp. lycopersici, S. oryzae, and S. sclerotiorum showed large variation in dual culture plate assay (Table ​(Table2).2). Only five isolates, viz. Amycolatopsis pretoriensis MSCA21, Saccharopolyspora shandongensis MSCA89, Kribbella karoonensis MSCA185, Streptomyces amritsarensis V31, and Streptomyces amritsarensis V49 showed consistent antifungal activities against all the phytopathogens. Hyphal growth of A. alternata was inhibited at a range between 4 and 90% in the presence of the evaluated actinomycetes isolates and among them, Kribbella karoonensis MSCA185 showed the highest (89.9%) reduction in hyphal growth. Approximately, 1.5–64% growth inhibition of R. solani was recorded with all the isolates. Saccharomonospora azurea MSCA47 showed the highest (64.6%) inhibition against R. solani. S. amritsarensis V31 was most effective against S. sclerotiorum with 44.8% reduction in hyphal growth. It was relatively effective against F. oxysporum f. sp. lycopersici and A. flavus showing 25.3% and 32% reduction in hyphal growth respectively, whereas Pseudarthrobacter siccitolerans MSCA72 was effective against S. oryzae with 43.8% reduction in hyphal growth.

Table 2

Antifungal activity of actinomycetes isolates against different phytopathogenic fungi

S. NoActinomycetes strainActinomycetesGrowth inhibition (%)
A. aR. sA. fF. oS. oS. s
1MJM11P. niigatensis13.9 ± 2.933.3 ± 7.82.0 ± 1.83.1 ± 2.70.010.3 ± 3.4
2MJM69K. paracochleata13.8 ± 1.618.7 ± 4.43.1 ± 0.35.5 ± 1.10.06.9 ± 3.4
3MSCA7P. chlorophenolius15.2 ± 7.51.5 ± 0.10.9 ± 1.60.00.06.9 ± 3.3
4MSCA21A. pretoriensis14.8 ± 1.418.1 ± 4.03.1 ± 0.39.5 ± 0.66.1 ± 2.320.7 ± 6.9
5MSCA26M. chalcea12.6 ± 3.239.4 ± 2.616.5 ± 3.60.00.020.7 ± 3.4
6MSCA47S. azurea8.9 ± 0.964.6 ± 7.20.03.9 ± 1.25.7 ± 3.96.9 ± 4.9
7MSCA53N. wenchangensis38.3 ± 2.036.4 ± 3.08.2 ± 1.53.1 ± 1.233.7 ± 3.20.0
8MSCA60M. chalcea13.8 ± 1.619.7 ± 2.67.2 ± 1.00.00.034.5 ± 3.4
9MSCA72P. siccitolerans71.3 ± 5.415.2 ± 1.52.2 ± 1.95.6 ± 1.843.8 ± 12.90.0
10MSCA89S. shandongensis4.0 ± 2.09.6 ± 0.94.2 ± 2.18.7 ± 0.914.4 ± 7.913.8 ± 3.4
11MSCA102P. siccitolerans38.7 ± 8.118.7 ± 3.50.00.023.1 ± 8.120.7 ± 3.4
12MSCA105B. rhamnosum9.9 ± 2.425.8 ± 6.90.017.6 ± 2.60.024.1 ± 3.4
13MSCA117P. aerolata21.9 ± 5.318.2 ± 2.60.04.0 ± 1.50.017.2 ± 3.0
14MSCA185K. karoonensis89.9 ± 7.512.6 ± 0.922.4 ± 4.713.4 ± 4.211.6 ± 4.33.4 ± 2.4
15B2M. jejuense19.5 ± 3.41.5 ± 0.22.0 ± 1.710.4 ± 4.20.00.0
16C6M. ginsengitense14.8 ± 1.426.3 ± 4.30.010.3 ± 1.00.00.0
17A17S. luridiscabiei23.0 ± 7.427.2 ± 5.35.9 ± 5.60.04.3 ± 1.93.4 ± 0.4
18A13S. harbinensis15.7 ± 3.121.7 ± 4.60.00.07.2 ± 1.934.4 ± 3.9
19V31S. amritsarensis41.4 ± 8.360.6 ± 6.332 ± 1.425.3 ± 2.131.8 ± 5.344.8 ± 3.3
20V49S. amritsarensis19.0 ± 8.731.3 ± 1.712.3 ± 2.04.0 ± 1.57.2 ± 2.810.3 ± 3.5

Values are presented as means ± standard deviation (SD) of three independent replicates. A. a. Alternaria alternata, R. s. Rhizoctonia solani, A. f. Aspergillus flavus, F. o. Fusarium oxysporum, S. o. Sarocladium oryzae, S. s. Sclerotinia sclerotiorum

Antifungal activity of extracts from actinomycetes against phytopathogens

Based on antifungal properties of actinomycetes, two potential isolates S. amritsarensis V31 and K. karoonensis MSCA185, showing high antifungal activity against all six fungal pathogens, were selected for further studies (Figs. ​(Figs.11 and ​and2).2). The crude extracts of these two isolates were evaluated for their antifungal activity via agar well diffusion assay. The results indicated that secondary metabolites extracted from S. amritsarensis V31 in four different solvents (EA, n-hexane, MeOH, and DMSO) inhibited the growth of all the fungal phytopathogens (Fig. 3, Supplementary Fig. 1). DMSO extract showed the highest antagonistic activity against all the test pathogens. The DMSO extract of S. amritsarensis V31 was recorded the highest antifungal activity against R. solani (65% growth inhibition) followed by S. oryzae (55.5%), A. alternata (47.2%), F. oxysporum f. sp. lycopersici (44%), S. sclerotiorum (40.5%), and A. flavus (30.7%). Methanolic (MeOH) extract of S. amritsarensis V31 inhibited the growth of R. solani, A. alternata, A. flavus, F. oxysporum f. sp. lycopersici, S. oryzae, and S. sclerotiorum by 60, 52.7, 23, 36, 44, and 29.7%, respectively. Meanwhile, the EA extract of S. amritsarensis V31 resulted in 7.5, 5.5, 8, 25, 11, and 35% growth inhibition of R. solani, A. alternata, A. flavus, F. oxysporum f. sp. lycopersici, S. oryzae, and S. sclerotiorum respectively. The n-hexane extract of S. amritsarensis V31 showed antifungal activity only against A. alternata and S. sclerotiorum and resulted in 11.1% and 32.4% growth inhibition respectively (Fig. 4). Metabolites extracted from K. karoonensis MSCA185 in different solvents showed antifungal activity toward F. oxysporum (2.85–11.6%) and S. sclerotium (25–34%) (Fig. 5).

An external file that holds a picture, illustration, etc. Object name is 42770_2021_625_Fig1_HTML.jpg

Antifungal activity of Streptomyces amritsarensis isolate V31 against different fungal pathogens; A. alternata (a), A. flavus (b), F. oxysporum f. sp. lycopersici (c), R. solani (d), S. oryzae (e), and S. sclerotiorum (f)

An external file that holds a picture, illustration, etc. Object name is 42770_2021_625_Fig2_HTML.jpg

Antifungal activity of Kribbella karoonensis isolate MSCA185 against different fungal pathogens; A. alternata (a), F. oxysporum f. sp. lycopersici (b), R. solani (c), and S. sclerotiorum (d)

An external file that holds a picture, illustration, etc. Object name is 42770_2021_625_Fig3_HTML.jpg

Antifungal activity of extracts of S. amritsarensis V31 in different solvents (ME, HE, DE, EE, and CE) during well diffusion assay against fungal pathogens S. sclerotiorum (a) and A. flavus (b). Here, ME, methanolic extract; HE, hexane extract; DE, DMSO (dimethylsulfoxide) extract; EE, ethyl acetate extract; and CE, crude and different solvent without extract used as a control was denoted by M, methanol; H, hexane; D, DMSO; E, ethyl acetate; and C, nutrient broth

An external file that holds a picture, illustration, etc. Object name is 42770_2021_625_Fig4_HTML.jpg

Antifungal activity (% inhibition) of metabolites extracted from Streptomyces amritsarensis strain V31 against different fungal pathogens; A. flavus (a), A. alternata (b), F. oxysporum f. sp. lycopersici (c), R. solani (d), S. oryzae (e), and S. sclerotiorum (f). Error bars represent SD. Bars with different letters are significantly different at p ≤ 0.05 according to Duncan’s multiple range test (DMRT). EA, ethyl acetate; MeOH, methanol; and DMSO, dimethyl sulfoxide

An external file that holds a picture, illustration, etc. Object name is 42770_2021_625_Fig5_HTML.jpg

Effect of metabolites extracted from Kribbella karoonensis isolate MSCA185 in different solvents against F. oxysporum f. sp. lycopersici and S. oryzae. Error bars represent SD. Bars with different letters are significantly different at p ≤ 0.05 according to Duncan’s multiple range test (DMRT). EA, ethyl acetate; MeOH, methanol; and DMSO, dimethyl sulfoxide

Effect of diluted extracts on fungal pathogens

After evaluating the antagonistic activity of crude extracts against fungal pathogens, these dilutions were further checked for the antifungal activity. Four different dilution folds (D) of all the solvents, i.e., 0, 10, 100, and 1000 D. 1000 D DMSO extracts of S. amritsarensis V31 recorded 19.2% and 19.4% inhibition against A. flavus and A. alternata. The antagonistic activity of DMSO extract of S. amritsarensis V31 against F. oxysporum f. sp. lycopersici (33.8%), S. oryzae (47.2%), S. sclerotiorum (29.7%), and R. solani (30%) was retained until 100 D. 1000 D methanolic extract of S. amritsarensis V31 showed growth inhibition against R. solani (23.3%), A. flavus (7.7%), F. oxysporum f. sp. lycopersici (22.2%), S. oryzae (16.7%), and S. sclerotiorum (19%) (Fig. 6).

An external file that holds a picture, illustration, etc. Object name is 42770_2021_625_Fig6_HTML.jpg

Effect of different dilutions of metabolites extracted from Streptomyces amritsarensis isolate V31 against A. alternata, R. solani, A. flavus, F. oxysporum f. sp. lycopersici, S. oryzae, and S. sclerotiorum. Four different dilutions (0, 10, 100, and 1000 D) of each solvent (EA, ethyl acetate; MeOH, methanol; DMSO, dimethylsulfoxide; hexane) extracted metabolites were used. Bars with different letters are significantly different at p ≤ 0.05 according to Duncan’s multiple range test (DMRT)

Furthermore, metabolites extracted from K. karoonensis MSCA185 strain in different solvents and their dilutions showed activity against F. oxysporum f. sp. lycopersici and S. sclerotiorum. 10 D ethyl acetate and DMSO extract of K. karoonensis MSCA185 recorded 2.9% and 10.5% inhibition of F. oxysporum f. sp. lycopersici while 1000 D ethyl acetate and methanolic extract of K. karoonensis MSCA185 showed 9.1% and 15.2% growth inhibition of S. sclerotiorum (Fig. 7).

An external file that holds a picture, illustration, etc. Object name is 42770_2021_625_Fig7_HTML.jpg

Effect of different dilution of extracted metabolites from Kribbella karoonensis isolate MSCA185 against F. oxysporum f. sp. lycopersici and S. oryzae fungal species. Four different dilutions (0, 10, 100, and 1000 D) of solvent extracted metabolites were used. Bars with different letters are significantly different at p ≤ 0.05 according to Duncan’s multiple range test (DMRT). Color bars used for different concentrations are as follows: 0D (gray), 10D (yellow), 100D (blue), and 1000D (red)

Effect of metabolites extract against rice sheath blight

In the present study, we examined the effect of metabolites extracted from S. amritsarensis V31 for antifungal activity against rice sheath blight pathogen under pot trials and observed a significant disease inhibition (Supplementary Fig. 2). The control plants (sprayed with only solvents without metabolites) produced typical symptoms of sheath blight like water-soaked, yellow-brownish, small to larger (1.03–1.07 cm dia) irregular spots and lesions near and on the leaf sheath which slowly damage the whole plant. On the other hand, plants sprayed with metabolites showed tiny brown dots of 0 to 0.2 (cm) size (Fig. 8). In the experiment with preventive spray, lesion size was up to 1.03 cm in the control plants. In contrast, the plants sprayed with metabolites extracts the lesions did not develop or the size was significantly small. Meanwhile, in curative treatment, lesion size of 1.07 cm was recorded in control plants, while the lesion size was significantly small in case of treated plants (Supplementary Table 1).

An external file that holds a picture, illustration, etc. Object name is 42770_2021_625_Fig8_HTML.jpg

Percentage inhibition of sheath blight disease in rice caused by R. solani isolate PU RS1 after spray of metabolites extracted from Streptomyces amritsarensis isolate V31

Identification of chemical compounds of extracted metabolite from S. amritsarensis V31

Secondary metabolites extracted in DMSO of S. amritsarensis V31 were analyzed through LC–MS. A total of 353 different chemical compounds were detected. Twenty major compounds present in the extract with known antimicrobial activities are presented in Table ​Table3.3. 6-amino-5-nitrosopyrimidine-2,4-diol was the most dominant compound present in the DMSO extract of S. amritsarensis V31. It was evident from the LC–MS analyses that S. amritsarensis V31 produced a mixture of potential antifungal compounds which could inhibit the growth of different phytopathogenic fungi.

Table 3

List of some bioactive molecules identified through LC–MS analyses of metabolites extracted from Streptomyces amritsarensis isolate V31

S. NoMetabolite Molecular formulaRetention timePeak area (%)Similarity (%)Activity against fungal phytopathogensReferences
16-amino-5-nitrosopyrimidine-2,4-diolC4H4N4O30.7629.8-Candida albicans, Candida tropicalis, and Cryptococcus neoformans43
25-[(2,2,6,6-Tetramethyl-4-piperidinyl)amino]-1,2,4-triazin-3(2H)-oneC21H21N5O4.0181.569.1Acinetobacter baumannii41
3Ethyl3-(2-methyl-2-propanyl)-1H-pyrazole-5-carboxylateC10H16N2O23.6951.282.3Aspergillus flavus, Penicillium marneffeii, Candida albicans, and Cryptococcus neoformans47
4BetaineC5H11NO20.6191.9-Malassezia restricta40
5Cyclo(leucylprolyl)C11H18N2O24.8341.288.4Colletotrichum acutatum, C. coccodes, C. gloeosporioides, Fusarium oxysporum, and Trichothecium roseum51
61-N-Boc-4-(azetidin-3-yl) piperazineC12H23N3O22.4210.89-Candida albicans, Aspergillus niger, Aspergillus flavus, and Aspergillus fumigatus52
76-(2-Ethoxyethoxy)-N,N′-diethyl-1,3,5-triazine-2,4-diamineC11H21N5O22.0090.6362.7Candida albicans, Aspergillus niger, and Aspergillus fumigatus50
8AmobarbitalC11H18N2O34.1730.56---
9tert-Butyl 2-amino-7,8-dihydropyrido[4,3-d]pyrimidine-6(5H)-carboxylateC12H18N4O21.7340.5279Candida albicans, Aspergillus fumigatus42
102-Methyl-2-propanyl [(2S)-1-hydrazino-3-(1H-imidazol-5-yl)-1-oxo-2-propanyl]carbamateC11H19N5O31.1840.5162.8--
11tert-butyl 4-carbamimidoylpiperidine-1-carboxylateC11H21N3O21.7170.4466.6Alternaria alternata, Ganoderma lucidum, Penicillium notatum, Trichoderma harzianum, and Aspergillus niger53
12Anthranilic acidC7H7NO24.1820.27-Candida albicans, Saccharomyces cerevisiae54
136-aminohexanoic acidC6H11N3O2---Candida albicans55
141-(2,2-Diethoxyethyl)-3,5-dimethyl-4-nitro-1H-pyrazoleC11H19N3O40.5190.04-Candida albicans, Trichophyton rubrum, Aspergillus flavus, Fusarium oxysporum, Scopulariopsis brevicaulis, and Geotrichum candidum48
15Methyl 4-Boc-piperazine-2-carboxylateC11H20N2O42.3180.03-Candida albicans, Aspergillus fumigatus56
162-piperidin-4-YL-benzooxazoleC12H14N2O7.1250.0384.5Candida albicans, C. glabrata57
17[(4,6-Dihydrazino-1,3,5-triazin -2-yl)oxy] acetonitrileC5H8N8O0.5270.03-Candida albicans, Aspergillus niger, Aspergillus clavatus49
182-(1,3-Benzodioxol-5-yl)-4,5,6,7-tetramethyl-1H-benzimidazoleC18H18N2O29.1020.03-Candida albicans, Aspergillus niger58
194-Amino-N,N-diethylbenzenesulfonamideC10H16N2O2S3.9910.0267.3T. longifusus, C. albicans, A. flavus, M. canis, F. solani, and C. glabrata59
204-{1-[1-(2-Methoxyethyl)-1H-tetrazol-5-yl]-2-methylpropyl}morpholineC12H23N5O22.7381.465.4Candida albicans and Trichophyton rubrum46

Discussion

Fungal pathogens cause significant damage to the crops leading to reduced productivity [26]. According to FAO, if the losses caused by fungal pathogens in five important crops, viz. rice, wheat, maize, potato, and soybean were mitigated, these crops would have been enough to supply foods to 8.5% of the world population [1]. Moreover, if these five crops were affected simultaneously, approximately 61% of the world’s population would not have food [1]. Phytopathogenic fungi like Rhizoctonia, Sclerotinia, Fusarium, Alternaria, Sarocladium, and Aspergillus are known to cause many dreaded diseases in a number of economically important crops [27–30]. Chemical fungicides are used to overcome the incidence of fungal diseases, but the continuous use of these chemicals has been known to cause persistent damage to soil and human health [31, 32]. Microorganisms and their metabolites offer a sustainable and ecofriendly alternative to agrochemicals. Among the microorganisms, actinomycetes are well known for their antimicrobial secondary metabolites [33]. It has been estimated that ~ 70% of the known secondary metabolites from microbes are produced by actinomycetes [34]. From Streptomyces alone, more than 10,000 bioactive compounds have been described [35]. A number of antifungal metabolites active against plant pathogens like Pyricularia oryzae, Cochliobolus miyabeanus, Colletotrichum gloeosporioides, Rhizoctonia solani, Botrytis cinerea, and Fusarium oxysporum are known to be produced by actinomycetes [14].

In this study, we evaluated twenty actinomycetes belonging to twelve different genera, viz. Micromonospora, Kitasatospora, Kribella, Amycalatopsis, Saccharomonospora, Nonomuraea, Saccharopolyspora, Pseudarthrobacter, Brachybacterium, Promicromonospora, Microbacterium, and Streptomyces for their antagonistic potential against six different phytopathogenic fungi. Many of these tested actinomycetes are already known for their activity against plant pathogenic fungi [36]. Isolates belonging to Saccharopolyspora, Amycolatopsis, Kribella, and Streptomyces showed variable degree of growth inhibition against all the tested phytopathogenic fungi. Among these, S. amritsarensis V31 turned to be highly effective against fungal pathogens. The extracted metabolites from S. amritsarensis V31 were also effective against these pathogens and could prevent incidence of sheath blight in rice plants. Sinha et al. (2014) reported that solvent extracted metabolites of Streptomyces plicatus inhibited the growth of Sclerotinia rolfsii and Phytophthora infestans up to 80–100% at concentrations ranging from 2000 to 5000 ppm [37]. Shi et al. (2018) reported the plant growth promoting and biocontrol activity of Streptomyces roseoflavus strain NKZ-259 against tomato in controlling the gray mold disease caused by Botrytis cinereus [13]. Streptomyces sp. SCA3-4 showed a broad-spectrum antifungal activity against 13 fungal pathogens [18]. Streptomyces sp. WA23-4–4 isolated from intestines of cockroach was reported to produce 3-acetylbenzamaide which could inhibit the growth of Aspergillus fumigatus, Aspergillus niger, and Candida albicans [38].

The possible mechanisms behind the antagonism of actinomycetes against fungi may include antimicrobial secondary metabolite production, secretion of lytic and fungal cell wall degrading enzymes, and competition for nutrients and space [39]. Streptomyces spp. produce several novel anti-cancerous compound such as salinosporamides, antimicrobial compounds like 5-[(2,2,6,6-Tetramethyl-4-piperidinyl) amino]-1,2,4-triazin-3 (2H) – one, and antifungal compound (Ethyl 3-(2-methyl-2-propanyl)-1H-pyrazole-5-carboxylate), betaine [40, 41]. In the present study, we could identify at least 20 major antimicrobial compounds from 535 metabolites identified through LC–MS. Majority of these contained pyrimidine, azide, azine, pyrazole, piperazine, amobarbital, carbamate, anthranilic acid, benzimidazole, and morpholine moiety in their backbone (Table ​(Table3;3; Supplementary Table 1). The results of the LC–MS analyses revealed that S. amrtisarensis V31 produced a mixture of several antifungal compounds which endowed it to inhibit growth of diverse phytopathogenic fungi. Nitrosopyrimidines with various substitutions have been reported as antifungal agents inhibiting the growth of Candida albicans, Candida tropicalis, Cryptococcus neoformans, and Aspergillus fumigatus [42, 43]. In the present study, 6-amino-5-nitrosopyrimidine-2,4-diol was found to be predominant in the extracts. Olivella et al. (2015) synthesized 35 different nitrosopyrimidines which had significant antibacterial activities against many pathogens [43]. It is pertinent to mention that although presence of such antimicrobial pyrimidines has been documented in plant extracts [44] showing antifungal activity, we could not find any report of nitrosopyrimidines of microbial origin. Presence of betaine was also detected in the S. amritsarensis V31 extract. Betaine was reported to inhibit the growth of Malassezia restricta known to be an opportunistic fungal pathogen of human [40]. Earlier, betaine was also identified in the methanolic extracts of antifungal compound producing Streptomyces sp. Go-475 through LC–MS [45]. Other compounds like those having morpholine, azine, or pyrazole and its derivatives could inhibit the growth of fungal pathogens [41, 46–59]. However, it was interesting to note that no antifungal antibiotics or peptides could be identified in the extract. The results clearly indicated that apart from antibiotics and antimicrobial peptides, other unique secondary metabolites were synthesized by Streptomyces offering it an adaptive advantage during competition for nutrient and space. Moreover, these unique microbial metabolite cocktails can be a lucrative ecofriendly option to control deadly plant diseases.

Acknowledgements

Authors are grateful to Director, ICAR-NBAIM, India, for financial and infrastructural support.

Author contribution

HC conceptualized the study. MS, BNS, SKG, SV, PC, and SD carried out experiments and generated the data. MS, BNS, and HC prepared the manuscript draft. HC, SV, and KM revised the draft. AKS and HC edited and finalized the manuscript.

Funding

This work is a part of Indian Soil Microbiome project being implemented at ICAR-NBAIM, India.

Data availability

Not applicable.

Declarations

Ethical approval

The manuscript does not contain experiments involving animal or human studies.

Conflict of interest

The authors declare no competing interests.

Footnotes

Publisher's note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

References

1. Fisher MC, Henk DA, Briggs CJ, Brownstein JS, Madoff LC, McCraw SL, Gurr SJ. Emerging fungal threats to animal, plant and ecosystem health. Nature. 2012;484(7393):186–194. 10.1038/nature10947. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
2. Garcia-Solache MA, Casadevall A. Global warming will bring new fungal diseases for mammals. mBio. 2010;1(1):e00061–10. 10.1128/mBio.00061-10. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
3. Scarpino V, Reyneri A, Sulyok M, Krska R, Blandino M. Effect of fungicide application to control Fusarium head blight and 20 Fusarium and Alternaria mycotoxins in winter wheat (Triticum aestivum L.) World Mycotoxin J. 2015;8(4):499–510. 10.3920/WMJ2014.1814. [CrossRef] [Google Scholar]
4. Talabi AO, Kayode TJ. Groundwater pollution and remediation. J Water Resour Prot. 2019;11(1):1–9. 10.4236/jwarp.2019.111001. [CrossRef] [Google Scholar]
5. Elahi E, Weijun C, Zhang H, Nazeer M. Agricultural intensification and damages to human health in relation to agrochemicals: application of artificial intelligence. Land Use Pol. 2019;83:461–474. 10.1016/j.landusepol.2019.02.023. [CrossRef] [Google Scholar]
6. Mohite OS, Weber T, Kim HU, Lee SY. Genome scale metabolic reconstruction of actinomycetes for antibiotics production. Biotechnol J. 2019;14(1):1800377. 10.1002/biot.201800377. [Abstract] [CrossRef] [Google Scholar]
7. Savi DC, Shaaban KA, Gos FM, Thorson JS, Glienke C, Rohr J. Secondary metabolites produced by Microbacterium sp. LGMB471 with antifungal activity against the phytopathogen Phyllosticta citricarpa. Folia Microbiol. 2019;64(3):453–60. 10.1007/s12223-018-00668-x. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
8. Kumar M, Kumar P, Das P, Kapur MK. Draft genome of Streptomyces sp. strain 130 and functional analysis of extracellular enzyme producing genes. Mol Biol Rep. 2019;46(5):5063–5071. 10.1007/s11033-019-04960-y. [Abstract] [CrossRef] [Google Scholar]
9. Verma VC, Singh SK, Prakash S. Bio-control and plant growth promotion potential of siderophore producing endophytic Streptomyces from Azadirachta indica A. Juss J Basic Microbiol. 2011;51(5):550–556. 10.1002/jobm.201000155. [Abstract] [CrossRef] [Google Scholar]
10. Anwar S, Ali B, Sajid I. Screening of rhizospheric actinomycetes for various in-vitro and in-vivo plant growth promoting (PGP) traits and for agroactive compounds. Front Microbiol. 2016;7:1334. 10.3389/fmicb.2016.01334. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
11. Palakawong NAS, Pristaš P, Hrehová L, Javorský P, Stams AJ, Plugge CM. Actinomyces succiniciruminis sp. nov. and Actinomyces glycerinitolerans sp. nov., two novel organic acid-producing bacteria isolated from rumen. Syst Appl Microbiol. 2016;39(2):445–452. 10.1016/j.syapm.2016.08.001. [Abstract] [CrossRef] [Google Scholar]
12. Palla MS, Guntuku GS, Muthyala MKK, Pingali S, Sahu PK. Isolation and molecular characterization of antifungal metabolite producing actinomycete from mangrove soil. Beni-Suef Univ J Basic Appl Sci. 2018;7(2):250–256. 10.1016/j.bjbas.2018.02.006. [CrossRef] [Google Scholar]
13. Shi L, Nwet TT, Ge B, Zhao W, Liu B, Cui H, Zhang K. Antifungal and plant growth-promoting activities of Streptomyces roseoflavus strain NKZ-259. Biol Cont. 2018;125:57–64. 10.1016/j.biocontrol.2018.06.012. [CrossRef] [Google Scholar]
14. Jakubiec-Krzesniak K, Rajnisz-Mateusiak A, Guspiel A, Ziemska J, Solecka J. Secondary metabolites of actinomycetes and their antibacterial, antifungal and antiviral properties. Pol J Microbiol. 2018;67(3):259–272. 10.21307/pjm-2018-048. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
15. Ahmad MS, El-Gendy AO, Ahmed RR, Hassan HM, El-Kabbany HM, Merdash AG. Exploring the antimicrobial and antitumor potentials of Streptomyces sp. AGM12–1 isolated from Egyptian soil. Front Microbiol. 2017;8:438. 10.3389/fmicb.2017.00438. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
16. Han L, Zhang G, Miao G, Zhang X, Feng J. Streptomyces kanasensis sp. nov., an antiviral glycoprotein producing actinomycete isolated from forest soil around Kanas lake of China. Curr Microbiol. 2015;71(6):627–631. 10.1007/s00284-015-0900-0. [Abstract] [CrossRef] [Google Scholar]
17. Ruanpanun P, Laatsch H, Tangchitsomkid N, Lumyong S. Nematicidal activity of fervenulin isolated from a nematicidal actinomycete, Streptomyces sp. CMU-MH021, on Meloidogyne incognita. World J Microbiol Biotechnol. 2011;27(6):1373–80. 10.1007/s11274-010-0588-z. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
18. Qi D, Zou L, Zhou D, Chen Y, Gao Z, Feng R, Zhang M, Li K, Xie J, Wang W. Taxonomy and broad-spectrum antifungal activity of Streptomyces sp. SCA3–4 isolated from rhizosphere soil of Opuntia stricta. Front Microbiol. 2019;10:1390. 10.3389/fmicb.2019.01390. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
19. Zhao S, Liu C, Zheng W, Ma Z, Cao T, Zhao J, Yan K, Xiang W, Wang X. Micromonospora parathelypteridis sp. nov., an endophytic actinomycete with antifungal activity isolated from the root of Parathelypteris beddomei (Bak.) Ching. Int J Syst Evol Microbiol. 2017;67(2):268–274. 10.1099/ijsem.0.001614. [Abstract] [CrossRef] [Google Scholar]
20. Orozco-Mosqueda CM, Valencia-Cantero E, Lopez-Albarran P, Martinez-Pacheco M, Velazquez-Becerra C. Bacterium Arthrobacter agilis UMCV2 and diverse amines inhibit in vitro growth of wood-decay fungi. Rev Argent Microbiol. 2015;47(3):219–228. 10.1016/j.ram.2015.06.005. [Abstract] [CrossRef] [Google Scholar]
21. Keel C, Weller DM, Natsch A, Defago G, Cook RJ, Thomashow LS. Conservation of the 2,4-diacetylphloroglucinol biosynthesis locus among fluorescent Pseudomonas strains from diverse geographic locations. Appl Environ Microbiol. 1996;62(2):552–563. 10.1128/AEM.62.2.552-563.1996. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
22. Mahdizadeh V, Safaie N, Khelghatibana F. Evaluation of antifungal activity of silver nanoparticles against some phytopathogenic fungi and Trichoderma harzianum. J Crop Prot. 2015;4(3):291–300. [Google Scholar]
23. Liu CX, Zhang J, Wang XJ, Qian PT, Wang JD, Gao YM, Yan YJ, Zhang SZ, Xu PF, Li WB, Xiang WS. Antifungal activity of borrelidin produced by a Streptomyces strain isolated from soybean. J Agric Food Chem. 2012;60(5):1251–1257. 10.1021/jf2044982. [Abstract] [CrossRef] [Google Scholar]
24. Tepe B, Daferera D, Sokmen A, Sokmen M, Polissiou M. Antimicrobial and antioxidant activities of the essential oil and various extracts of Salvia tomentosa Miller (Lamiaceae) Food Chem. 2005;90(3):333–340. 10.1016/j.foodchem.2003.09.013. [CrossRef] [Google Scholar]
25. Sharma NR, Teng PS, Oliver FM. Comparisons of assessment methods for rice sheath blight disease. Philipp Phytopathol. 1990;26(12):20–24. [Google Scholar]
26. Almeida F, Rodrigues ML, Coelho C. The still underestimated problem of fungal diseases worldwide. Front Microbiol. 2019;10:214. 10.3389/fmicb.2019.00214. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
27. Derbyshire MC, Denton-Giles M. The control of Sclerotinia stem rot on oilseed rape (Brassica napus): current practices and future opportunities. Plant Pathol. 2016;65(6):859–877. 10.1111/ppa.12517. [CrossRef] [Google Scholar]
28. Moni ZR, Ali MA, Alam MS, Rahman MA, Bhuiyan MR, Mian MS, Iftekharuddaula MK, Latif MA, Khan MAI. Morphological and genetical variability among Rhizoctonia solani isolates causing sheath blight disease of rice. Rice Sci. 2016;23(1):42–50. 10.1016/j.rsci.2016.01.005. [CrossRef] [Google Scholar]
29. Guimarães RA, Lobo VL, Côrtes MV, Filippi MC, Prabhu AS. Characterization of Sarocladium oryzae and its reduction potential of rice leaf blast. Pesqui Agropecu Trop. 2017;47(1):41–52. 10.1590/1983-40632016v4742738. [CrossRef] [Google Scholar]
30. Ramírez-Cariño HF, Guadarrama-Mendoza PC, Sánchez-López V, Cuervo-Parra JA, Ramírez-Reyes T, Dunlap CA, Valadez-Blanco R. Biocontrol of Alternaria alternata and Fusarium oxysporum by Trichoderma asperelloides and Bacillus paralicheniformis in tomato plants. Antonie Van Leeuwenhoek. 2020;113(9):1247–1261. 10.1007/s10482-020-01433-2. [Abstract] [CrossRef] [Google Scholar]
31. Baibakova EV, Nefedjeva EE, Suska-Malawska M, Wilk M, Sevriukova GA, Zheltobriukhov VF. Modern fungicides: mechanisms of action, fungal resistance and phytotoxic effects. Annu Res Rev Biol. 2019;32(3):1–16. 10.9734/arrb/2019/v32i330083. [CrossRef] [Google Scholar]
32. Rani L, Thapa K, Kanojia N, Sharma N, Singh S, Grewal AS, Srivastav AL, Kaushal J. An extensive review on the consequences of chemical pesticides on human health and environment. J Cleaner Prod. 2020;283:124657. 10.1016/j.jclepro.2020.124657. [CrossRef] [Google Scholar]
33. Ding T, Yang LJ, Zhang WD, Shen YH. The secondary metabolites of rare actinomycetes: chemistry and bioactivity. RSC Adv. 2019;9(38):21964–21988. 10.1039/C9RA03579F. [CrossRef] [Google Scholar]
34. Zhang D, Lu Y, Chen H, Wu C, Zhang H, Chen L, Chen X. Antifungal peptides produced by actinomycetes and their biological activities against plant diseases. J Antibiot. 2020;73(5):265–282. 10.1038/s41429-020-0287-4. [Abstract] [CrossRef] [Google Scholar]
35. Weber T, Charusanti P, Musiol-Kroll EM, Jiang X, Tong Y, Kim HU, Lee SY. Metabolic engineering of antibiotic factories: new tools for antibiotic production in actinomycetes. Trends Biotechnol. 2015;33(1):15–26. 10.1016/j.tibtech.2014.10.009. [Abstract] [CrossRef] [Google Scholar]
36. Tian SZ, Pu X, Luo G, Zhao LX, Xu LH, Li WJ, Luo Y. Isolation and characterization of new p-terphenyls with antifungal, antibacterial, and antioxidant activities from halophilic actinomycete Nocardiopsis gilva YIM 90087. J Agric Food Chem. 2013;61(12):3006–3012. 10.1021/jf400718w. [Abstract] [CrossRef] [Google Scholar]
37. Sinha K, Hegde R, Kush A. Exploration on native actinomycetes strains and their potential against fungal plant pathogens. Int J Curr Microbiol App Sci. 2014;3(11):37–45. [Google Scholar]
38. Fang X, Shen J, Wang J, Chen ZL, Chen ZY, Liu LY, Zeng HX, Jin XB. Antifungal activity of 3-acetylbenzamide produced by actinomycete WA23-4-4 from the intestinal tract of Periplaneta americana. J Microbiol. 2018;56:516–523. 10.1007/s12275-018-7510-z. [Abstract] [CrossRef] [Google Scholar]
39. Baz M, Lahbabi D, Samri S, Val F, Hamelin G, Madore I, Bouarab K, Beaulieu C, Ennaji MM, Barakate M. Control of potato soft rot caused by Pectobacterium carotovorum and Pectobacterium atrosepticum by Moroccan actinobacteria isolates. World J Microbiol Biotechnol. 2012;28:303–311. 10.1007/s11274-011-0820-5. [Abstract] [CrossRef] [Google Scholar]
40. Do E, Lee HG, Park M, Cho YJ, Kim DH, Park SH, Eun D, Park T, An S, Jung WH. Antifungal mechanism of action of lauryl betaine against skin-associated fungus Malassezia restricta. Mycobiol. 2019;47(2):242–249. 10.1080/12298093.2019.1625175. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
41. Ivanova V, Lyutskanova D, Kolarova M, Aleksieva K, Raykovska V, Stoilova-Disheva M. Structural elucidation of a bioactive metabolites produced by Streptomyces avidinii SB9 strain, isolated from permafrost soil in Spitsbergen. Arctic Biotechnol Biotechnol Equip. 2010;24(4):2092–2095. 10.2478/V10133-010-0080-9. [CrossRef] [Google Scholar]
42. Abd El-Wahab AHF. Synthesis, reactions and evaluation of the antimicrobial activity of some 4-(p-Halophenyl)-4H-naphthopyran, pyranopyrimidine and pyranotriazolopyrimidine derivatives. Pharm. 2012;5(7):745–757. 10.3390/ph5070745. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
43. Olivella M, Marchal A, Nogueras M, Melguizo M, Lima B, et al. New series of antibacterial nitrosopyrimidines: synthesis and structure–activity relationship. Arch Pharm. 2015;348(1):68–80. 10.1002/ardp.201400271. [Abstract] [CrossRef] [Google Scholar]
44. de Rodríguez DJ, Gaytán-Sánchez NA, Rodríguez-García R, Hernández-Castillo FD, Díaz-Jiménez L, et al. Antifungal activity of Juglans spp. and Carya sp. ethanol extracts against Fusarium oxysporum on tomato under greenhouse conditions. Ind Crops Prod. 2019;138:111442. 10.1016/j.indcrop.2019.06.005. [CrossRef] [Google Scholar]
45. Kibret M, Guerrero-Garzón JF, Urban E, Zehl M, Wronski VK, et al. Streptomyces spp. from Ethiopia producing antimicrobial compounds: characterization via bioassays, genome analyses, and mass spectrometry. Front Microbiol. 2018;9:1270. 10.3389/fmicb.2018.01270. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
46. Polak A, Jäckel A, Noack A, Kappe R. Agar sublimation test for the in vitro determination of the antifungal activity of morpholine derivatives. Mycoses. 2004;47:184–192. 10.1111/j.1439-0507.2004.00975.x. [Abstract] [CrossRef] [Google Scholar]
47. Titi A, Messali M, Alqurashy BA, Touzani R, Shiga T, Oshio H, Fettouhi M, Rajabi M, Almalki FA, Hadda TB. Synthesis, characterization, X-ray crystal study and bioactivities of pyrazole derivatives: identification of antitumor, antifungal and antibacterial pharmacophore sites. J Mol Struct. 2020;1205:127625. 10.1016/j.molstruc.2019.127625. [CrossRef] [Google Scholar]
48. Zaki RM, Abdul-Malik MA, Saber SH, Radwan SM, El-Dean AMK. A convenient synthesis, reactions and biological evaluation of novel pyrazolo[3,4-b]selenolo[3,2-e]pyrazine heterocycles as potential anticancer and antimicrobial agents. Med Chem Res. 2020;29(12):2130–2145. 10.1007/s00044-020-02635-z. [CrossRef] [Google Scholar]
49. Baldaniya BB, Patel PK. Synthesis, antibacterial and antifungal activities of s-triazine derivatives. J Chem. 2009;6(3):673–680. 10.1155/2009/196309. [CrossRef] [Google Scholar]
50. Bhat M, Belagali SL. Structural activity relationship and importance of benzothiazole derivatives in medicinal chemistry: a comprehensive review. Mini-Rev Org Chem. 2020;17(3):323–350. 10.2174/1570193X16666190204111502. [CrossRef] [Google Scholar]
51. Kim YJ, Kim JH, Rho JY. Antifungal activities of Streptomyces blastmyceticus strain 12–6 against plant pathogenic fungi. Mycobiology. 2019;47(3):329–334. 10.1080/12298093.2019.1635425. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
52. Suryavanshi HR. Synthesis and biological activities of piperazine derivatives as antimicrobial and antifungal agents. Org Commun. 2017;10(3):228. 10.25135/acg.oc.23.17.05.026. [CrossRef] [Google Scholar]
53. Hussain S, Ali S, Shahzadi S, Sharma SK, Qanungo K, Shahid M. Synthesis, characterization, semiempirical and biological activities of organotin (IV) carboxylates with 4-piperidinecarboxylic acid (2014) Bioinorg Chem Appl 959203. 10.1155/2014/959203 [Europe PMC free article] [Abstract]
54. Li CS, Li XM, Gao SS, Lu YH, Wang BG. Cytotoxic anthranilic acid derivatives from deep sea sediment-derived fungus Penicillium paneum SD-44. Mar Drug. 2013;11(8):3068–3076. 10.3390/md11083068. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
55. Amirkhanov NV, Tikunova NV, Pyshnyi DV. Synthetic antimicrobial peptides: I. antimicrobial activity of amphiphilic and nonamphiphilic cationic peptides Rus. J Bioorganic Chem. 2018;44(5):492–503. 10.1134/S1068162018050035. [CrossRef] [Google Scholar]
56. Kondoh O, Inagaki Y, Fukuda H, Mizuguchi E, Ohya Y, Arisawa M, Shimma N, Aoki Y, Sakaitani M, Watanabe T. Piperazine propanol derivative as a novel antifungal targeting 1, 3-β-D-glucan synthase. Biol Pharm Bull. 2005;28(11):2138–2141. 10.1248/bpb.28.2138. [Abstract] [CrossRef] [Google Scholar]
57. Carvalho A, Chu J, Meinguet C, Kiss R, Vandenbussche G, Masereel B, Wouters J, Kornienko A, Pelletier J, Mathieu V. A harmine-derived beta-carboline displays anti-cancer effects in vitro by targeting protein synthesis. Eur J Pharmaco. 2017;805:25–35. 10.1016/j.ejphar.2017.03.034. [Europe PMC free article] [Abstract] [CrossRef] [Google Scholar]
58. Khabnadideh S, Rezaei Z, Pakshir K, Zomorodian K, Ghafari N. Synthesis and antifungal activity of benzimidazole, benzotriazole and aminothiazole derivatives. Res Pharm Sci. 2012;7(2):65. [Europe PMC free article] [Abstract] [Google Scholar]
59. Chohan ZH. Metal-based sulfonamides: their preparation, characterization and in-vitro antibacterial, antifungal & cytotoxic properties. X-ray structure of 4-[(2-hydroxybenzylidene) amino] benzenesulfonamide (2008) J Enzyme Inhib Med Chem. 2008;23(1):120–30. 10.1080/14756360701384195. [Abstract] [CrossRef] [Google Scholar]
Articles from Brazilian Journal of Microbiology are provided here courtesy of Brazilian Society of Microbiology

Full text links 

Read article at publisher's site: https://doi.org/10.1007/s42770-021-00625-w

Read article for free, from open access legal sources, via Unpaywall: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8578481Unpaywall

Citations & impact 

Impact metrics

5
Citations
Jump to Citations

Citations of article over time

Smart citations by scite.ai
Smart citations by scite.ai include citation statements extracted from the full text of the citing article. The number of the statements may be higher than the number of citations provided by EuropePMC if one paper cites another multiple times or lower if scite has not yet processed some of the citing articles.
Explore citation contexts and check if this article has been supported or disputed.
https://scite.ai/reports/10.1007/s42770-021-00625-w

Supporting
Mentioning
Contrasting
0
7
0

Article citations

Similar Articles 

To arrive at the top five similar articles we use a word-weighted algorithm to compare words from the Title and Abstract of each citation.