Natural Product‐Based Fungicides Discovery: Design,Synthesis and Antifungal Activities of Some Sarisan Analogs Containing 1,3,4‐Oxadiazole Moieties

A series of sarisan analogs containing 1,3,4‐oxadiazole moieties were synthesized by iodine‐mediated oxidative cyclization and screened in vitro for their antifungal activities at 50 μg/mL against five phytopathogenic fungi such as Valsa mali, Curvularia lunata, Alternaria alternate, Fusarium solani and Fusarium graminearum. 1,3,4‐Oxadiazole derivatives 7e , 7p , 7r , 7t and 7u exhibited potent and a broad spectrum of antifungal activities against at least three phytopathogenic fungi at the concentration of 50 μg/mL. Especially, compound 7r displayed more potent antifungal activities against five phytopathogenic fungi than the positive control hymexazol. The EC₅₀ of 7r against V. mali, C. lunata and A. alternate were 12.6, 14.5 and 17.0 μg/mL, respectively. Additionally, some interesting results of structure‐activity relationships (SARs) were also observed.     

Antifungal activity of six Saudi medicinal plant extracts against five phyopathogenic fungi

Six medicinal plants such as Amaranthus spinosus, Barbeya oleoides, Clutia lanceolata, Lavandula pubescens, Maerua oblongifolia and Withania somnifera collected from different locations in the southwestern part of Saudi Arabia were tested for antifungal activities against five plant pathogenic fungi causing serious diseases of vegetable crops. These fungi were Alternaria brassicae, Alternaria solani, Botrytis fabae, Fusarium solani and Phytophthora infestans. Aqueous plant extracts reduced mycelial growth and inhibited spore germination of all fungi tested. It is clear that the aqueous extract of Lavandula pubescens leaves was the best for controlling all phytopathogenic fungi under study. These results suggested that medicinal plant extracts play an important role in controlling the phytopathogenic fungi.     

Antimycotic activities of Cinnamon-derived compounds against <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> in vitro

In this study, the effects of medicinal plant extracts on the development of mycelium in the following phytopathogenic fungi were evaluated: Phytophthora capsici, Rhizoctonia solani, Fusarium solani, Colletotrichum gloeosprorioides, and Botrytis cinera. Of the 26 medicinal plants tested, six plant extracts showed antifungal activity against phytopathogenic fungi. The highest antifungal activity was exerted against R. solani by the n-hexane fraction of a Cinnamon (Cinnamomum cassia Blume) solvent extract. Therefore, the antifungal compound fractions I and II were purified from the n-hexane fraction by TLC on silica gel plates. When treated with solutions containing compound fractions I or II at a concentration of 2%, the mycelia growth rate of R. solani was reduced to 0.19 and 0.18, respectively. In addition, microscopic observation of the hyphal morphology of R. solani following treatment with compound fraction I revealed the presence of severely damaged hyphae. Specifically, the hyphal tips became swollen, collapsed or were completely destroyed in response to treatment with solution containing compound fraction I at concentration of 1%.     

Synthesis,Antifungal Activity,DFT Study and Molecular Dynamics Simulation of Novel 4-(1,2,4-Oxadiazol-3-yl)-N-(4-phenoxyphenyl)benzamide Derivatives

In order to find novel potential antifungal agrochemicals, a series of new 4-(1,2,4-oxadiazol-3-yl)-N-(4-phenoxyphenyl)benzamide derivatives 3a – j were designed, synthesized and characterized by their ¹H - , ¹³C-NMR and HRMS spectra. The preliminary antifungal assay in vitro revealed that compounds 3a – j exhibited moderate to good antifungal activity against five plant pathogenic fungi. Especially, compound 3e presented significant antifungal activity against Alternaria solani, Botrytis cinerea and Sclerotinia sclerotiorum, superior to positive control boscalid. In the in vivo antifungal assay on tomato plants and cucumber leaves, compound 3e presented good inhibition rate against B. cinerea at 200 mg/L. Molecular dynamics simulation revealed that compound 3e could bind with the active site of class II histone deacetylase (HDAC).     

Antifungal Activities of N-Arylbenzenesulfonamides against Phytopathogens and Control Efficacy on Wheat Leaf Rust and Cabbage Club Root Diseases

A set of N-arylbenzenesulfonamides with various substituents at the arylamine and benzenesulfonyl positions were prepared, and their antifungal properties were measured in vitro against such plant pathogenic fungi as Pythium ultimum, Phytophthora capsici, Rhizoctonia solani, and Botrytis cinerea. Compounds 3, 4, 8, 9, 10, 14, 16, 18, 20, 21, 24 and 27 had antifungal activity over a broad spectrum of the phytopathogenic fungi tested, where 50% of inhibition (ED₅₀) was in the range of 3-15 μg/ml. Based on the in vitro activity, six derivatives (3, 4, 10, 18, 21 and 27) were selected and tested further for their fungicidal efficacy in vivo. The fungicidal efficacy of 10, 21 and 27 had a disease control value of over 85% at 50 μg/ml against wheat leaf rust, while that of 4 was selective against cabbage club root disease.     

黄花倒水莲内生真菌生物活性评价及HNLF-44菌株鉴定

为充分开发黄花倒水莲(Polygala fallax)的内生真菌资源，获得具有抗植物病原真菌、抗氧化活性的内生真菌，该文以黄花倒水莲内生真菌为研究对象，使用平板对峙法检测内生真菌对6种植物病原真菌的抑菌活性，测定内生真菌发酵液的DPPH清除自由基能力和总还原能力，评价内生真菌的抗氧化活性，并对具有强抑菌活性和抗氧化活性的菌株进行形态和ITS鉴定。结果表明：(1)黄花倒水莲内生真菌中有2株内生真菌对香蕉专化尖孢镰刀菌、柑橘树脂病菌、叶点霉菌、香蕉具条叶斑病菌、茄病镰刀菌、三七根腐病菌具有明显的抑菌活性，抑菌率在50.3%～91.4%之间，其中HNLF-5对柑橘树脂病菌的抑菌率为73.2%,HNLF-44对香蕉专化尖孢镰刀菌抑菌率为91.4%。(2)内生真菌发酵液具有良好的抗氧化活性，DPPH清除率均在80%以上，总还原能力吸光值范围为0.279 2～0.748 8。(3)HNLF-44菌株为链格孢属真菌。该研究表明，药用植物黄花倒水莲内生真菌具有较好的生物活性，为后续从黄花倒水莲内生真菌中挖掘潜在新型抑菌活性和抗氧化活性物质奠定了基础。     

Herbal remedies for the management of seed-borne fungal pathogens by an edible plant Decalepis hamiltonii (Wight & Arn)

Abstract

Antifungal activity-guided assay of solvent extracts of Decalepis hamiltonii (Wight & Arn) (Asclepiadaceae) against important phytopathogenic fungi, known to cause diseases in sorghum, maize and paddy proved to be highly significant. Among the five solvent extracts tested, Petroleum ether extract showed highly significant antifungal activity. Phytochemical analysis revealed that the antifungal active principle is a phenolic compound. TLC separation of the phenolic fraction using chloroform as an eluting solvent revealed the presence of seven bands but the antifungal activity was observed only in band five with R_f value 0.77. The antifungal active compound is identified as 2-hydroxy-4-methoxybenzaldehyde based on Nuclear Magnetic Resonance (NMR) and mass spectral analysis. The Minimal inhibitory concentration (MIC) varied between 200 μg ml^?1 and 700 μg ml^?1 depending on the fungal species. Seed treatment of the active principle significantly increased seed germination and seed vigour with a corresponding decrease in seed mycoflora. The antifungal active compound was effective against all the 24 fungal species tested suggesting broad-spectrum antifungal activity. Comparative evaluation of the active principle with the synthetic fungicides revealed that the antifungal activity of the active principle obtained from the plant is better than that of synthetic fungicide. This plant being an edible one can be exploited in the management of seed-borne pathogenic fungi and the prevention of biodeterioration of grains and mycotoxin elaboration during storage.     

Laticifer proteins play a defensive role against hemibiotrophic and necrotrophic phytopathogens

Proteins from latex of Calotropis procera (CpLP), Plumeria rubra (PrLP), Carica candamarcensis (P1G10) and Euphorbia tirucalli (EtLP) were tested for antifungal activity against phytopathogens. CpLP and P1G10 inhibited each fungi analyzed. PrLP and EtLP did not exert inhibition. CpLP and P1G10 exhibited preferential inhibitory activity towards R. solani (IC₅₀ = 20.7 and 25.3 μg/ml, respectively). The inhibitory activity was lost after heat treatment or proteolysis, providing evidence for the involvement of proteins in the inhibitory effect. Treatment of CpLP or P1G10 with Dithiothreitol improved both, the endogenous proteolytic activity and the antifungal properties. Conversely, pre-treatment of CpLP or P1G10 with iodoacetamide drastically reduced endogenous proteolytic activities and partially abrogated antifungal activity. Similar results were observed when spores were challenged to germinate in the presence of laticifer proteins. The purified cysteine proteinase CMS2MS2 from Carica candamarcensis latex or papain (E.C. 3.4.22.2), a cysteine proteinase from latex of Carica papaya L., but not trypsin (EC 3.4.21.4) or chymotrypsin (EC 3.4.21.1), two serine proteases, replicated the results obtained with CpLP or P1G10, thus restricting the antifungal property to latex plant cysteine proteinases. CpLP, CMS2MS2 and papain induced production of reactive oxygen species in spores of F. solani, suggesting that inhibition could be linked to oxidative stress. Proteome analysis of CpLP by 2-D electrophoresis and MALDI-TOF-TOF confirmed the existence of various pathogenic-related proteins such as chitinases, peroxidases and osmotins. The results support that laticifer proteins are part of plant defense repertoire against phytopathogenic fungi.     

Synthesis and Antifungal Activity of Curcumol Derivatives

To discover novel and effective antifungal candidates, a series of new curcumol derivatives were designed, synthesized, and evaluated their antifungal activity against five phytopathogenic fungi by the mycelium growth rate method. Derivatives c4 , c22 and c23 exhibited excellent antifungal activity against Phomopsis sp. with EC₅₀ values of 3.06, 3.07, and 3.16 μM, respectively. Specifically, compound c4 exhibited the strongest antifungal activity against Phomopsis sp., which was 44 times that of pyrimethanil (EC₅₀=134.37 μM). The results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that compound c4 could cause cell senescence and death of Phomopsis sp. by changing the normal hyphal morphology and disrupting the normal metabolism of hyphal cells. Moreover, compound c4 showed excellent curative effect against Phomopsis sp. on kiwifruit. These findings confirmed that compound c4 has great potential as a potent antifungal agent.     

Essential oil composition of Angelica archangelica L. (Apiaceae) roots and its antifungal activity against plant pathogenic fungi

This study reports the results of gas chromatography–mass spectrometry (GC–MS) analyses of the essential oil of Angelica archangelica L. (Apiaceae) roots, as well as its in vitro antifungal activity against 10 plant pathogenic fungi. Moreover, the essential oil was evaluated for its antifungal activity using the agar dilution method, and also minimum inhibitory concentrations and minimum fungicidal concentrations were determined. The major compounds identified by GC–MS were α-pinene (21.3%), δ-3-carene (16.5%), limonene (16.4%), and α-phellandrene (8.7%). The oil showed in vitro antifungal activity against some species of the Fusarium genus, Botrytis cinerea, and Alternaria solani. Our study indicates that the oil of A. archangelica could be used as a control agent for plant pathogenic fungi in natural formulations.     

Study of the antifungal activity of <Emphasis Type="Italic">Acinetobacter baumannii</Emphasis> LCH001 in vitro and identification of its antifungal components

An Acinetobacter strain, given the code name LCH001 and having the potential to be an endophytic antagonist, has been isolated from healthy stems of the plant Cinnamomum camphora (L.) Presl, guided by an in vitro screening technique. The bacterium inhibited the growth of several phytopathogenic fungi such as Cryphonectria parasitica, Glomerella glycines, Phytophthora capsici, Fusarium graminearum, Botrytis cinerea, and Rhizoctonia solani. Biochemical, physiological, and 16S rDNA sequence analysis proved that it is Acinetobacter baumannii. When the filtrate from the fermentation broth of strain LCH001 was tested in vitro and in vivo, it showed strong growth inhibition against several phytopathogens including P. capsici, F. graminearum, and R. solani, indicating that suppression of the growth of the fungi was due to the presence of antifungal compounds in the culture broth. Moreover, the antifungal activity of the culture filtrate was significantly correlated with the cell growth of strain LCH001. The active metabolites in the filtrate were relatively thermally stable, but were sensitive to acidic conditions. Three antifungal compounds were isolated from the culture broth by absorption onto macropore resin, ethanol extraction, chromatography on silica gel or LH-20 columns, and crystallization. The structures of the bioactive compounds were identified by spectroscopic methods as isomers of iturin A, namely, iturin A2, iturin A3, and iturin A6. The characterization of an unusual endophytic bacterial strain LCH001 and its bioactive components may provide an alternative resource for the biocontrol of plant diseases.     

Endophytic Bacterial Communities in Ginseng and their Antifungal Activity Against Pathogens

Plant roots are associated with diverse communities of endophytic bacteria which do not exert adverse effects. The diversity of bacterial endophytes associated with ginseng roots cultivated in three different areas in Korea was investigated. Sixty-three colonies were isolated from the interior of ginseng roots. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolates belonged to three major phylogenetic groups: the high G+C Gram-positive bacteria (HGCGPB), low G+C Gram-positive bacteria (LGCGPB), and the Proteobacteria. The dominant species at the three different ginseng growing areas were: HGCGPB at Ganghwa (55.0%), LGCGPB at Geumsan (45.5%), and Proteobacteria at Jinan (61.9%). Most cellulase-, xylanase-, and pectinase-producing colonies among the isolates belong to the LGCGPB group, except for Pectobacterium carotovora which belonged to the Proteobacteria. The 13 isolates belonging to LGCGPB and Proteobacteria were assessed for their antifungal activity against phytopathogenic fungi such as Rhizoctonia solani. Among them, Paenibacillus polymyxa GS01, Bacillus sp. GS07, and Pseudomonas poae JA01 show potential activity as biocontrol agents against phytopathogenic fungi. Finally, most of the low G+C Gram-positive bacteria with antifungal activity against phytopathogenic microorganisms showed cellulolytic enzyme activity while some Proteobacteria with the antifungal activity and the high G+C Gram-positive bacteria did not show any cellulolytic activity.     

Antifungal Activity of Volatile Compounds Produced by an Edible Mushroom Hypsizygus marmoreus against Phytopathogenic Fungi

Volatile compounds with antifungal activity produced by edible mushrooms have potential as biological control agents to combat fungal diseases and reduce fungicide use in agriculture. Here we investigated the antifungal activity of volatile compounds produced by the edible mushroom Hypsizygus marmoreus (TUFC 11906) against eight phytopathogenic fungi. The results showed that volatile compounds from the mycelia and culture filtrates (CFs) of H. marmoreus had antifungal activity against some phytopathogenic fungi. Among them, the mycelial growth and conidial germination of Alternaria brassicicola were significantly inhibited by 60 and 100%, respectively. Moreover, the volatile compounds from CFs inhibited the lesion formation of A. brassicicola on detached cabbage leaves by 94%. The volatile compounds had higher antifungal activity against A. brassicicola than other fungi. With the removal of the volatile compounds from conidia of A. brassicicola, the conidia began to germinate, which indicates fungistatic activity of the compounds. The volatile compounds were isolated from the CFs of H. marmoreus, and the major volatile compound with antifungal activity was estimated to be 2‐methylpropanoic acid 2,2‐dimethyl‐1‐(2‐hydroxy‐1‐methylethyl)propyl ester. As the volatile compound produced by H. marmoreus is a product of an edible mushroom and has fungistatic activity against some phytopathogenic fungi, especially A. brassicicola, it may be possible to use the compounds as a novel safe agent for protecting crops in the field and during storage.     

Quinoline Alkaloids from the Roots of Orixa japonica with the Anti-Pathogenic Fungi Activities

A new quinoline alkaloid, 5-hydroxy-6-methoxy-N-methyl-2-phenylquinoline-4-one ( 1 ), and seventeen known quinoline alkaloids ( 2 – 18 ) were isolated from the roots of Orixa japonica. The structure of 1 was determined by analysis of spectroscopic data. Among them, compounds 2 , 3 , and 13 were isolated from this plant for the first time. All isolates were screened for the anti-pathogenic fungi activities, including Rhizoctonia solani, Magnaporthe oryzae, and Phomopsis sp. The results showed that five compounds ( 4 , 8 , 10 , 11 , and 12 ) exhibited significant anti-pathogenic fungi effects at 50.0 μg/mL. In special, compound 10 exhibited the best antifungal activities toward R. solani and M. oryzae with the IC₅₀ values of 37.86 and 44.72 μM, respectively, better than that of the positive control, hymexazol (IC₅₀ 121.21 and 1518.18 μM, respectively). Moreover, eleven new quinoline alkaloids derivatives ( 12a–12k ) were designed and synthesized to investigate the structure−activity relationships (SARs). The SARs analysis indicated that the furo[2,3-b]quinoline skeleton and the methoxy at C-7 (compounds 8 , 11 , and 12 ) played a key role for improving the antifungal activities.     

Design,Synthesis, and Antifungal Activities of Novel Carboxamides Derivatives Bearing a Chalcone Scaffold as Potential SDHIs

In search for SDHIs fungicides, twenty-five novel carboxamides containing a chalcone scaffold were designed, synthesized, and evaluated for antifungal activities against five pathogenic fungi. The results showed that compound 5 k exhibited outstanding antifungal activity against R. solani with an EC₅₀ value of 0.20 μg/mL, which was much better than that of commercial SDHIs Boscalid (EC₅₀=0.74 μg/mL). Moreover, compound 5 k also displayed promising antifungal activities against S. sclerotiorum, B. cinerea, and A. alternate (IC₅₀=2.53–4.06 μg/mL), indicating that 5 k had broad-spectrum antifungal activity. Additionally, in vivo antifungal activities results showed that 5 k could significantly inhibit the growth of R. solani in rice leaves with good protective efficacy (57.78 %) and curative efficacy (58.45 %) at 100 μg/mL, both of which were much better than those of Boscalid, indicating a promising application prospect. Moreover, SEM analysis showed that compound 5 k could remarkably disrupt the typical structure and morphology of R. solani hyphae. Further SDH enzyme inhibition assay and molecular docking study revealed that lead compound 5 k had a similar mechanism of action as commercial SDHI Boscalid. These results indicated that compound 5 k showed potential as a SDHIs fungicide and deserved further investigation.     

Bioactive stilbenes from a Bacillus sp. N strain associated with a novel rhabditid entomopathogenic nematode

Aims: The aim of the present study was to purify and characterize a natural antimicrobial compound from Bacillus sp. strain N associated with a novel rhabditid entomopathogenic nematode. Methods and Results: The cell‐free culture filtrate of a bacterium associated with a novel entomopathogenic nematode (EPN), Rhabditis (Oscheius) sp. exhibited strong antimicrobial activity. The ethyl acetate extract of the bacterial culture filtrate was purified by column chromatography, and two bioactive compounds were isolated and their chemical structures were established based on spectral analysis. The compounds were identified as 3,4′,5‐trihydroxystilbene (1) and 3,5‐dihydroxy‐4‐isopropylstilbene (2). The presence of 3,4′,5‐trihydroxystilbene (resveratrol) is reported for the first time in bacteria. Compound 1 showed antibacterial activity against all the four test bacteria, whereas compound 2 was effective against the Gram‐positive bacteria only. Compounds 1 and 2 were active against all the five fungi tested and are more effective than bavistin, the standard fungicide. The antifungal activity of the compounds against the plant pathogenic fungi, Rhizoctonia solani is reported for the first time. Conclusions: Cell‐free extract of the bacterium and isolated stilbenes demonstrated high antibacterial activity against bacteria and fungi especially against plant pathogenic fungi. We conclude that the bacterium‐associated EPN are promising sources of natural bioactive secondary metabolites. Significance and Impact of the Study: Stilbene compounds can be used for the control of fungi and bacteria.     

4-Aminoquinolines Bearing a 1,3-Benzodioxole Moiety: Synthesis and Biological Evaluation as Potential Antifungal Agents

In search of new environmentally friendly and effective antifungal agents, a series of 4-aminoquinolines bearing a 1,3-benzodioxole moiety were prepared and their structures were fully elucidated by spectroscopic analyses. The antifungal activities of all the target compounds against five phytopathogenic fungi were evaluated in vitro. The results revealed that most of the newly synthesized compounds exhibited obvious inhibitory activities at the concentration of 50 μg/mL. Among them, 6-(furan-2-yl)-N-(4-methylphenyl)-2H-[1,3]dioxolo[4,5-g]quinolin-8-amine hydrochloride ( 7m ) displayed more promising antifungal potency with EC₅₀ values of 10.3 and 14.0 μg/mL against C. lunata and A. alternate, respectively. Particularly, the EC₅₀ value of 7m against C. lunata was 7.3-fold as potent as the standard azoxystrobin. There were some significant morphological alterations in the mycelia of C. lunata when treated with 7m at 50 μg/mL. Additionally, the preliminary structure–activity relationships (SARs) were also discussed. Thus, this study suggests that 4-aminoquinolines bearing a 1,3-benzodioxole moiety are interesting scaffolds for the development of novel antifungal agents.     

New Insights into the Structure and Mode of Action of Mo-CBP3, an Antifungal Chitin-Binding Protein of Moringa oleifera Seeds

Mo-CBP₃ is a chitin-binding protein purified from Moringa oleifera Lam. seeds that displays inhibitory activity against phytopathogenic fungi. This study investigated the structural properties and the antifungal mode of action of this protein. To this end, circular dichroism spectroscopy, antifungal assays, measurements of the production of reactive oxygen species and microscopic analyses were utilized. Mo-CBP₃ is composed of 30.3% α-helices, 16.3% β-sheets, 22.3% turns and 30.4% unordered forms. The Mo-CBP₃ structure is highly stable and retains its antifungal activity regardless of temperature and pH. Fusarium solani was used as a model organism for studying the mechanisms by which this protein acts as an antifungal agent. Mo-CBP₃ significantly inhibited spore germination and mycelial growth at 0.05 mg.mL⁻¹. Mo-CBP₃ has both fungistatic and fungicidal effects, depending on the concentration used. Binding of Mo-CBP₃ to the fungal cell surface is achieved, at least in part, via electrostatic interactions, as salt was able to reduce its inhibitory effect. Mo-CBP₃ induced the production of ROS and caused disorganization of both the cytoplasm and the plasma membrane in F. solani cells. Based on its high stability and specific toxicity, with broad-spectrum efficacy against important phytopathogenic fungi at low inhibitory concentrations but not to human cells, Mo-CBP₃ has great potential for the development of new antifungal drugs or transgenic crops with enhanced resistance to phytopathogens.     

Synthesis and Antifungal Activities of Trichodermin Derivatives as Fungicides on Rice

Twenty new trichodermin derivatives, 2a – 5 , containing alkoxy, acyloxy, and Br groups in 4‐, 8‐, 9‐, 10‐ and 16‐positions were synthesized and characterized. The antifungal activities of the new compounds against rice false smut (Ustilaginoidea virens), rice sheath blight (Rhizoctonia solani), and rice blast (Magnaporthe grisea) were evaluated. The results of bioassays indicated that the antifungal activities were particularly susceptible to changes at 4‐, 8‐, and 16‐positions, but low to changes at 9‐ and 10‐positions. Most of these target compounds exhibited good antifungal activities at the concentration of 50 mg l^?1. Compound 4 (9‐formyltrichodermin; EC₅₀ 0.80 mg l^?1) with an CHO group at 9‐position displayed nearly the same level of antifungal activity against Ustilaginoidea virens as the commercial fungicide prochloraz (EC₅₀ 0.82 mg l^?1), while compound 3f ((8R)‐8‐{[(E)‐3‐phenylprop‐2‐enoyl]oxy}trichodermin; EC₅₀ 3.58 and 0.74 mg l^?1) with a cinnamyloxy group at C(8) exhibited much higher antifungal activities against Rhizoctonia solani and Magnaporthe grisea than the commercial fungicides prochloraz (EC₅₀ 0.96 mg l^?1) and propiconazole (EC₅₀ 5.92 mg l^?1), respectively. These data reveal that compounds 3f and 4 possess high antifungal activities and may serve as lead compounds for the development of fungicides in the future.     

Characteristics and antimicrobial activity of <Emphasis Type="Italic">Bacillus subtilis</Emphasis> strains isolated from soil

Antagonistic Bacillus strains were isolated from soil and analyzed for the purpose of determining whether they could be used as natural biological agents. Primary in vitro screening for antagonism of the isolates was performed against five phytopathogenic mould fungi. Strains TS 01 and ZR 02 exhibited the most pronounced inhibitory effects. They were identified as Bacillus subtilis on the basis of their morphological, cultural and physiology-biochemical properties as well as their hierarchical cluster analysis conducted by means of computer program SPSS. The antimicrobial activity of the strains from cultural medium and sterile filtrate were determined in vitro against a great number of predominantly phytopathogenic fungi and bacteria. TS 01 and ZR 02 strains exhibited very broad and at the same time degree varying antibiotic spectra of activities against both Gram-positive and Gram-negative microorganisms. Many of them were tested against sensitivity to the antimicrobial action of B. subtilis for the very first time. B. subtilis TS 01 and ZR 02 showed highest antifungal activity (sterile zone in diameter over 37 mm) against Alternaria solani, Botrytis cinerea, Monilia linhartiana 869, Phytophthora cryptogea 759/1 and Rhizoctonia sp. The most sensitive bacterial species were found to be Pseudomonas syringae pv. tomato Ro and Xanthomonas campestris with sterile zones 48.0 and 50.0 mm in diameter, respectively. The latter draws a conclusion that the isolated and identified Bacillus subtilis strains are promising natural biocontrol agents and should be further studied and tested for control of numerous plant diseases.