PLANT DISEASE CONTROL COMPOSITION COMPRISING CULTURE BROTH OF Streptomyces sp. JCK-6141 STRAIN OR EXTRACT OF CULTURE BROTH OF STRAIN, PREPARATION METHOD THEREFOR AND PLANT DISEASE CONTROL METHOD

Abstract

The present disclosure relates to a plant disease control composition comprising a culture broth of Streptomyces sp. JCK-6141 strain or an extract of the culture broth of the strain, a preparation method therefor and a plant disease control method. The culture broth of the strain or an extract thereof exhibits extremely excellent antimicrobial activity when applied to a causative pathogen of plant disease and thus may be effectively used for plant disease control.

Claims

1. A Streptomyces sp. JCK-6141 strain, deposited with accession number KCTC 14333BP, having antimicrobial activity.

2. A composition for controlling plant diseases, comprising a culture of a Streptomyces sp. JCK-6141 strain deposited with accession number KCTC 14333BP or an extract from the culture.

3. The composition of claim 2, wherein the plant disease is caused by at least one phytopathogen selected from the group consisting of a fungus and an oomycete.

4. The composition of claim 3, wherein the fungus is at least one species selected from the group consisting of Athelida rolfsii, Botryosphaeria dothidea, Botrytis cinerea, Colletotrichum caudatum, Colletotrichum cocodes, Colletotrichum horii, Curvularia lunata, Endothia parasitica, Fusarium fujikuroi, Fusarium graminearum, Fusarium oxysporum f. sp. raphani, Fusarium oxysporum f. sp. lycopersici, Fusarium oxysporum f. sp. cucumerinum, Gaeumannomyces graminis, Magnaporthiopsis poae, Magnapothe oryzae, Pseudocercospora circumcissa, Raffaelea quercus-mongolicae, Rhizoctonia solani, Rhizoctonia cerealis, Sclerotinia homoeocarpa, and Valsa cerasperma.

5. The composition of claim 3, wherein the fungus is Puccinia recondita.

6. The composition of claim 3, wherein the oomycete is at least one species selected from the group consisting of Phytophthora cactorum, Phytophthora cambivora, Phytophthora capsici, Phytophthora cinnamomi, Pythium graminicola, and Pythium ultimum.

7. The composition of claim 2, wherein the extract from the culture comprises at least one selected from the group consisting of reveromycin E, reveromycin E 1-methyl ester, and a reveromycin E derivative.

8. A method for preparation of a composition for controlling a plant disease, comprising a step of culturing a Streptomyces sp. JCK-6141 strain deposited with accession number KCTC 14333BP to afford a culture.

9. The method of claim 8, wherein the plant disease is caused by at least one phytopathogen selected from the group consisting of a fungus and an oomycete.

10. The method of claim 9, wherein the fungus is at least one species selected from the group consisting of Athelida rolfsii, Botryosphaeria dothidea, Botrytis cinerea, Colletotrichum caudatum, Colletotrichum cocodes, Colletotrichum horii, Curvularia lunata, Endothia parasitica, Fusarium fujikuroi, Fusarium graminearum, Fusarium oxysporum f. sp. raphani, Fusarium oxysporum f. sp. lycopersici, Fusarium oxysporum f. sp. cucumerinum, Gaeumannomyces graminis, Magnaporthiopsis poae, Magnapothe oryzae, Pseudocercospora circumcissa, Raffaelea quercus-mongolicae, Rhizoctonia solani, Rhizoctonia cerealis, Sclerotinia homoeocarpa, and Valsa cerasperma.

11. The method of claim 9, wherein the fungus is Puccinia recondita.

12. The method of claim 9, wherein the oomycete is at least one species selected from the group consisting of Phytophthora cactorum, Phytophthora cambivora, Phytophthora capsici, Phytophthora cinnamomi, Pythium graminicola, and Pythium ultimum.

13. The method of claim 8, wherein the culturing step comprises the following fractionation steps: a first fractionation step of obtaining a first active fraction from the culture; a second fractionation step of obtaining a second active fraction from the first active fraction using column chromatography and thin layer chromatography; a third fractionation step of obtaining a third active fraction from the second active fraction using high-pressure liquid chromatography; a fourth fractionation step of separating a fourth active fraction from the third active fraction using preparative thin layer chromatography; and a pure substance identification step of identifying the fourth active fraction by high-performance liquid chromatography.

14. The method of claim 13, wherein the pure substance is at least one selected from the group consisting of reveromycin E, reveromycin E 1-methyl ester, and a reveromycin E derivative.

15.-16. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0075] FIG. 1 is a photographic image showing the mycelial growth inhibitory effect of Streptomyces sp. JCK-6141 strain on phytopathogens according to an embodiment of the present disclosure.

[0076] FIG. 2 is a schematic diagram of a process of isolating and identifying reveromycin E (F61), reveromycin E 1-methyl ester (F71), and reveromycin E derivative (F81) from the Streptomyces sp. JCK-6141 strain culture according to an embodiment of the present disclosure.

[0077] FIG. 3A is an HPLC chromatogram of fraction F61 isolated from a culture of Streptomyces sp. JCK-6141 strain culture according to an embodiment of the present disclosure.

[0078] FIG. 3B is an HPLC chromatogram of fraction F71 isolated from a culture of Streptomyces sp. JCK-6141 strain culture according to an embodiment of the present disclosure.

[0079] FIG. 3C is an HPLC chromatogram of fraction F81 isolated from a culture of Streptomyces sp. JCK-6141 strain culture according to an embodiment of the present disclosure.

[0080] FIG. 4A is a negative ion-mode ESI-MS spectrum of reveromycin E (F61) isolated from a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

[0081] FIG. 4B is a positive ion-mode ESI-MS spectrum of reveromycin E (F61) isolated from a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

[0082] FIG. 5A is a negative ion-mode ESI-MS spectrum of reveromycin E 1-methyl ester (F71) isolated from a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

[0083] FIG. 5B is a positive ion-mode ESI-MS spectrum of reveromycin E 1-methyl ester (F71) isolated from a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

[0084] FIG. 6A is a negative ion-mode ESI-MS spectrum of reveromycin E (F81) isolated from a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

[0085] FIG. 6B is a positive ion-mode ESI-MS spectrum of a reveromycin E derivative (F81) isolated from a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

[0086] FIG. 7A shows a structural formula illustrating the chemical structure of reveromycin E (F61) isolated and identified from a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

[0087] FIG. 7B shows a chemical structure of reveromycin E 1-methyl ester (F71) isolated and identified from a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

[0088] FIG. 8 is a photographic image showing the inhibitory activity against 21 phytopathogenic fungi and oomycetes of an ethyl acetate fraction of a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

[0089] FIG. 9A is a graph eludicating controlling effects against cucumber damping-off in 1 DBI treated with a culture of Streptomyces sp. JCK-6141 strain and an ethyl acetate fraction thereof according to an embodiment of the present disclosure.

[0090] FIG. 9B is a photographic image showing controlling effects against cucumber damping-off in 1 DBI treated with a culture of Streptomyces sp. JCK-6141 strain and an ethyl acetate fraction thereof according to an embodiment of the present disclosure.

[0091] FIG. 10A is a graph eludicating controlling effects against cucumber damping-off in 1 HAI treated with a culture of Streptomyces sp. JCK-6141 strain and an ethyl acetate fraction thereof according to an embodiment of the present disclosure.

[0092] FIG. 10B is a photographic image showing controlling effects against cucumber damping-off in 1 HAI treated with a culture of Streptomyces sp. JCK-6141 strain and an ethyl acetate fraction thereof according to an embodiment of the present disclosure.

[0093] FIG. 11A is a graph eludicating controlling effects against Fusarium wilt in 1 DBI treated with a culture of Streptomyces sp. JCK-6141 strain and an ethyl acetate fraction thereof according to an embodiment of the present disclosure.

[0094] FIG. 11B is a photographic image showing controlling effects against Fusarium wilt in 1 DBI treated with a culture of Streptomyces sp. JCK-6141 strain and an ethyl acetate fraction thereof according to an embodiment of the present disclosure.

[0095] FIG. 12A is a graph eludicating controlling effects against cucumber Fusarium wilt in 1 HAI treated with a culture of Streptomyces sp. JCK-6141 strain and an ethyl acetate fraction thereof according to an embodiment of the present disclosure.

[0096] FIG. 12B is a photographic image showing controlling effects against Fusarium wilt in 1 HAI treated with a culture of Streptomyces sp. JCK-6141 strain and an ethyl acetate fraction thereof according to an embodiment of the present disclosure.

[0097] FIG. 13 is a photographic image showing the controlling effects against rice sheath blight in the rice cultivar Nakdong treated with a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

[0098] FIG. 14 is a photographic image showing the controlling effects against wheat leaf rust in the wheat cultivar Eunpa treated with a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

[0099] FIG. 15 is a photographic image showing the controlling effects against Fusarium head blight in the wheat cultivar Eunpa treated with a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

[0100] FIG. 16A is a graph eludicating controlling effects against dollar spot disease in creeping bentgrass treated with a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

[0101] FIG. 16B is a photographic image showing the controlling effects against dollar spot disease in creeping bentgrass treated with a culture of Streptomyces sp. JCK-6141 strain according to an embodiment of the present disclosure.

BEST MODE FOR CARRYING OUT THE INVENTION

[0102] The present disclosure relates to Streptomyces sp. JCK-6141 strain, deposited under accession number KCTC 14333BP, having antifungal activity.

MODE FOR CARRYING OUT THE INVENTION

[0103] Hereinafter, the present disclosure will be described in more detail through examples. These examples are only for illustrating the present disclosure in more detail, and it will be apparent to those skilled in the art that the scope of the present disclosure is not limited by these examples according to the gist of the present disclosure.

[0104] Unless otherwise stated, % used to indicate the concentration of a specific substance is (weight/weight) % for solid/solid, (weight/volume) % for solid/liquid, and (volume/volume) % for liquid/liquid throughout the specification.

Example 1. Isolation of Streptomyces sp. JCK-6141 Strain

[0105] Strains with plant disease control activity were isolated from the weed rhizosphere (soil environment in which growing roots absorb and store substances and thus make various changes to the proportion of constituent organisms) in Gokseong, Jeollanam-do, South Korea. After being sampled, 1 g of soil was diluted in phosphate buffered saline (pH 7.0), spread on a tryptic soy agar (TSA) plate, and incubated for 3 to 7 days at 30 C. to isolate strains.

Example 2. Molecular Biological Analysis and Phylogenetic Analysis of Streptomyces sp. JCK-6141 Strain

[0106] Molecular biological identification was made of the strain isolated from the soil by sequencing 16S rRNA. The strain was inoculated into ISP2 medium and then cultured with shaking at 180 rpm at 28 C. for 7 days. Then, genomic DNA (gDNA) of the strain was extracted using the 1-genomic BYF DNA Extraction Mini kit (iNtRON Biotechnology, Korea) according to the protocol. Specifically, the extracted gDNA of the strain was mixed with PCR-premix (polymerase chain reaction-premix, iNtRON Biotechnology, Korea) and the primer set 9F/1512R capable of amplifying the 16S rRNA of the strain, listed Table 1 below, before PCR amplification.

TABLE-US-00001 TABLE1 SEQID NO: Name Sequence(5.fwdarw.3) bp 1 JCK-614116SrRNA9F GAGTTTGATCCTGGCTCA 18 forwardprimer bp 2 JCK-614116SrRNA1512R ACGGCTACCTTGTTACGACTT 21 reverseprimer bp

[0107] PCR started at 95 C. for 5 minutes and proceeded with 30 rounds of 95 C. for 30 seconds, 55 C. for 30 seconds, and 72 C. for 30 seconds, followed by extension at 72 C. for 7 minutes and termination at 12 C.

[0108] The PCR product of 16S rRNA gene was based sequenced by Genotech (Daejeon, Korea).

[0109] The 16S rRNA encoding nucleotide sequence of the isolated JCK-6141 strain was determined to have a total nucleotide sequence of 1338 bp, and the results are shown in Table 2.

TABLE-US-00002 TABLE2 SEQ ID NO: Name Sequence(5.fwdarw.3) bp 3 JCK-6141 GGATTAGTGGCGAACGGGTG 1338 16SrRNA AGTAACACGTGGGCAATCTG bp CCCTTCACTCTGGGACAAGC CCTGGAAACGGGGTCTAATA CCGGATATGAGCCTGGGAGG CATCTCCCGGGTTGTAAAGC TCCGGCGGTGAAGGATGAGC CCGCGGCCTATCAGCTTGTT GGTGAGGTAATGGCTCACCA AGGCGACGACGGGTAGCCGG CCTGAGAGGGCGACCGGCCA CACTGGGACTGAGACACGGC CCAGACTCCTACGGGAGGCA GCAGTGGGGAATATTGCACA ATGGGCGAAAGCCTGATGCA GCGACGCCGCGTGAGGGATG ACGGCCTTCGGGTTGTAAAC CTCTTTCAGCAGGGAAGAAG CGAAAGTGACGGTACCTGCA GAAGAAGCGCCGGCTAACTA CGTGCCAGCAGCCGCGGTAA TACGTAGGGCGCAAGCGTTG TCCGGAATTATTGGGCGTAA AGAGCTCGTAGGCGGCTTGT CACGTCGATTGTGAAAGCCC GAGGCTTAACCTCGGGTCTG CAGTCGATACGGGCTAGCTA GAGTGTGGTAGGGGAGATCG GAATTCCTGGTGTAGCGGTG AAATGCGCAGATATCAGGAG GAACACCGGTGGCGAAGGCG GATCTCTGGGCCATTACTGA CGCTGAGGAGCGAAAGCGTG GGGAGCGAACAGGATTAGAT ACCCTGGTAGTCCACGCCGT AAACGGTGGGAACTAGGTGT TGGCGACATTCCACGTCGTC GGTGCCGCAGCTAACGCATT AAGTTCCCCGCCTGGGGAGT ACGGCCGCAAGGCTAAAACT CAAAGGAATTGACGGGGGCC CGCACAAGCGGOGGAGCATG TGGCTTAATTCGACGCAACG CGAAGAACCTTACCAAGGCT TGACATACACCGGAAAGCAT TAGAGATAGTGCCCCCCTTG TGGTCGGTGTACAGGTGGTG CATGGCTGTCGTCAGCTCGT GTCGTGAGATGTTGGGTTAA GTCCCGCAACGAGCGCAACC CTTGTTCTGTGTTGCCAGCA TGCCCTTCGGGGTGATGGGG ACTCACAGGAGACCGCCGGG GTCAACTCGGAGGAAGGTGG GGACGACGTCAAGTCATCAT GCCCCTTATGTCTTGGGCTG CACACGTGCTACAATGGCCG GTACAATGAGCTGCGATACC GTGAGGTGGAGCGAATCTCA AAAAGCCGGTCTCAGTTCGG ATTGGGGTCTGCAACTCGAC CCCATGAAGTCGGAGTCGCT AGTAATCGCAGATCAGCATT GCTGCGGTGAATACGTTCCC GGGCCTTGTACACACCGCCC GTCACGTCACGAAAGTCGGT AACACCCGAAGCCGGTGG

[0110] Based on the nucleotide sequence, the homology test of the nucleotide sequence was performed using the Blast program (http://www.ncbi.nlm.nhi.gov) for registered information (GenBank database). As a result, as shown in Table 3, the strain was identified as Streptomyces sp., named Streptomyces sp. JCK-6141, and was deposited with accession name KCTC 14333BP.

TABLE-US-00003 TABLE 3 JCK-6141 gene to be based Similarity sequenced Identification through NCBI BlastN analysis (%) 16S rRNA Streptomyces sp. HPF1204 (LC515800) 99.85 Streptomyces sp. Z2 (AF068055) 99.85 Streptomyces sp. MR602 (LC381941) 99.48

Example 3. Assay for Mycelial Growth Inhibitory Activity and Enzyme Activity of Streptomyces sp. JCK-6141 Strain Against Plant Pathogens

[0111] In order to examine the effect of the isolated and selected Streptomyces sp. JCK-6141 strain on the growth of plant pathogens, measurement was made of inhibitory activity against the growth of the three plant pathogens Fusarium oxysporum f. sp. cucumerinum, Pythium ultimum, and Rhizoctonia solani. Mycelial fragments of the plant pathogens obtained from cultures growing at high growth rates were inoculated into one part of PDA (Potato Dextrose Agar) medium which was separately inoculated in a straight line with Streptomyces sp. JCK-6141 at a site 2.5 cm away from the inoculated part, then incubated at 28 C. When the plant pathogens grew to the edge under monitoring, degrees of inhibition against mycelial growth of the plant pathogens by the Streptomyces sp. JCK-6141 strain were measured, and the results are shown in FIG. 1.

[0112] As shown in FIG. 1, Streptomyces sp. JCK-6141 strain strongly inhibited the growth of plant pathogens Fusarium oxysporum f. sp. cucumerinum, Pytium ultimate, and Rhizoctonia solani.

Example 4. Measurement of Minimum Inhibitory Concentration of Streptomyces sp. JCK-6141 Strain Against Mycelial Growth of Plant Pathogens

[0113] The separated and selected Streptomyces sp. JCK-6141 strain was measured for minimum inhibitory concentrations against the mycelial growth of plant pathogens. Streptomyces sp. JCK-6141 strain was inoculated into a Glucose-Soybean meal-Sodium chloride (GSS) broth and then cultured with shaking at 180 rpm at 28 C. for 7 days. After centrifuging the culture at 4500 rpm for 20 minutes, the supernatant thus obtained was filtered through a 0.2 m sterile filter to obtain the culture filtrate (hereinafter referred to as the sample). The sample was applied at concentrations of 0.16, 0.32, 0.63, 1.25, 2.5, 5, and 10% to plant pathogens mycelia. Mycelia of the plant pathogens Fusarium oxysporum f. sp. lycopersici, Pythium ultimum, Rhizoctonia solani, Botrytis cinerea, and Fusarium oxysporum f. sp. cucumerinum were cultured stationarily at 25 C. for 7 days in a PDB medium. After the concentration of the mycelia was adjusted into 500 g/ml (w/v), the mycelia were ground using a blender (DBIHAN, HG-15D).

[0114] The ground mycelia were added in an amount of 180 L to each well of 96-well plates to which 20 L of the sample was dispensed to form a concentration of 10%. Then, 100 L was taken from each well treated at a concentration of 10% and mixed with 100 L of the ground mycelia in a neighbor well to form a concentration of 5%. The dilution was repeated in such a serial dilution manner to prepare concentrations of 0.16, 0.32, 1.25, 2.5, 5, and 10%. After incubation for 24 hours at 25 C., degrees of mycelial growth were measured, and for each group, the experiment was performed in triplicate.

TABLE-US-00004 TABLE 4 MIC values (%) Fusarium Fusarium oxysporum oxysporum f. sp. Pythium Rhizoctonia Botrytis f. sp. Strain lycopersici ultimum solani cinerea cucumerinum JCK- 0.63 0.31 0.63 0.31 0.31 6141

[0115] As shown in Table 4, the culture filtrate of Streptomyces sp. JCK-6141 strain exhibited potent inhibitory activity against the mycelial growth of various plant pathogens such as Fusarium oxysporum f. sp. lycopaceae, Pytium Ultium, Rhizoctonia solani, Botrytis cinerea, and Fusarium oxysporum f. sp. cucumerinum. Although slightly differing in the concentration of 100% growth inhibition from one pathogen to another, the strain showed MIC values (%) of 0.31 to 0.63.

Example 5. Isolation of Antimicrobial Active Substance from Streptomyces sp. JCK-6141 Strain and Structural Identification Thereof

[0116] 5-1. Isolation of Antimicrobial Active Substance

[0117] In order to isolate the antimicrobial active substance produced by Streptomyces sp. JCK-6141 strain, the strain was inoculated in a Glucose-Soybean meal-Sodium chloride (GSS) broth and then cultured at 28 C. for 7 days with shaking at 180 rpm. Thereafter, a supernatant was obtained by briefly spinning the culture medium (total 3 L) at 400 rpm for 10 minutes, as shown in FIG. 2. The supernatant was adjusted to a pH of 2 and fractionated twice with ethyl acetate (3 L) to prepare an ethyl acetate fraction (first active fraction) of Streptomyces sp. JCK-6141 strain culture.

[0118] The prepared ethyl acetate fraction (first active fraction) was concentrated using a vacuum concentrator. For further purifying antimicrobial active substances, silica gel column chromatography was performed. In this regard, the fraction was loaded into a silica gel column (500 g, 200-400 mesh), followed by elution with chloroform:methanol (8:2, 1 L), chloroform:methanol (7:3, 1 L), and chloroform:methanol:water:acetic acid (30:9:1:0.25, 2 L). Drops of the eluted fractions were loaded to the silica gel plate for thin layer chromatography (0.25 mm film thickness) and then developed with chloroform:methanol:water:acetic acid (30:9:1:0.25). Absorbance was read at 254 nm. After para-anisaldehyde reagent was sprayed thereto, fractions with similar color development were collected and concentrated under reduced pressure.

[0119] Among the fractions concentrated under reduced pressure, one fraction showing antifungal activity against Rhizoctonia solani (second active fraction) was selected. Substances were separated from the fraction using Atlantis T3f prep OBDTM (5 m, 19250 mm) column-equipped preparative high-performance liquid chromatography (Waters, Japan). For this, 0.1% trifluoroacetic acid (TFA)-added distilled water and acetonitrile were used as an eluent. Distilled water containing 0.1% trifluoroacetic acid was added to acetonitrile to prepare 50% to 70% acetonitrile solutions. Elution was performed with 50% to 70% acetonitrile solutions at a flow rate of 15 ml/min for 50 minutes. As a result of elution, a total of 14 fractions (F1 to F14, the third active fraction) were obtained.

[0120] Among them, the three fractions F6, F7, and F8 that exhibited antifungal activity were fractioned by preparative thin layer chromatography (silica gel thin layer chromatography, 0.5 mm film thickness). Chloroform:methanol:water:acetic acid (30:9:1:0.25) was used as the developing solvent. As a result, active F61 (35.2 mg), F71 (15.3 mg), and F81 (9.2 mg) (fourth activity) fraction) were obtained.

[0121] Active pure substances were identified in F61, F71, and F81 thus obtained. In this regard, high-performance liquid chromatography was performed while the amount of organic solvent was started from 50% acetonitrile solution on Xbridge C18 (4.6250 mm, 5 um) column, increasing to 100% acetonitrile solution in 35 minutes. Active substances were detected by a PDA (photodiode array) detector at a detection wavelength of 240 nm. The results are shown in FIGS. 3A to 3C. In particular, F71 was observed to have two isomers or almost similar substances in a mixture at a ratio of 1:1.

[0122] 5-2. Molecular Weight Identification of Active Antimicrobial Substances

[0123] The three substances F61, F71, and F81 isolated from Streptomyces sp. JCK-6141 strain were lyophilized and measured for molecular weights through liquid chromatography electrospray mass method (LC-ESI-MS, API2000, ABSCIEX, USA) in negative and positive ion modes, and the results are depicted in FIGS. 4A to 6B.

[0124] As shown in FIGS. 4A and 4B, [M1] and [M+Na]+ ion peaks of F61 appeared at m/z 687.3749 in negative ion mode and 711.3725 in positive ion mode, respectively, giving the molecular formula C.sub.38H.sub.56O.sub.11 with a molecular weight of 688. In the case of F71, as shown in FIGS. 5A and 5B, ion peaks were observed at m/z 701.3885 for [M1] in negative ion mode and at m/z 725.3878 for [M+Na]+ in positive ion mode, giving the molecular formula C.sub.39H.sub.58O.sub.11 with a molecular weight of 702. In addition, as shown in FIGS. 6A and 6B, ion peaks of F81 appeared at m/z 715.4095 for [M1] ion in negative ion mode and at m/z 739.4048 for [M+Na]+ in positive ion mode, indicating the molecular formula of C.sub.40H.sub.60O.sub.11 with a molecular weight of 716. The compounds F71 and F81 were estimated to be reveromycin E derivatives as their molecular weights showed a difference of 14 and 28, respectively, when compared to F61.

[0125] 5-3. Chemical Structures of Active Antifungal Substances

[0126] In order to identify the chemical structures of F61 and F71, various modes of NMR analysis were performed. Among them, NMR data for F61 are summarized in Table 5 below.

TABLE-US-00005 TABLE 5 Position H C COSY HMBC 1 168.87 2, 3, 1-ME 2 5.82 (dt) 121.25 3, 4 1, 4, 5, 1-ME 3 6.98 (dd) 151.27 2, 4 1, 2, 4, 5, 4-Me 4 2.53 (q) 42.89 3, 5 2, 3, 5, 4-Me 5 4.07 (q) 75.68 4, 6, 7, 4-Me 4, 6, 7, 4-Me 6 5.52 (m) 126.52 4, 5, 7 5, 7, 8 7 6.25 (dd) 136.3 5, 6 5, 6, 8, 8-Me 8 140.36 9, 10, 8-Me 9 5.55 (d) 126.41 7, 10a 8, 10, 8-Me 10a 2.38 (dt) 31.57 9, 11 8, 9, 11, 8-Me 10b 1.83 (d) 11 3.46 (dt) 74.87 10a, 12 9, 10 12 1.42 (dd) 33.38 11, 13, 12-Me 10a, 11, 13 13a 1.48 (m) 27.37 14a 11, 12, 14, 15 13b 1.53 (dd) 14a 1.74 (d) 35.5 13a 14b 1.45 (d) 13, 15, 16 15 95.66 14, 16, 17 16a 1.83 (d) 31.36 17 14, 15, 17, 18 16b 1.60 (d) 17 15, 17, 18 17a 2.02 (m) 24.04 16ab, 17b 15 17b 2.34 (t) 16ab, 19 18, 19, 20 18 82.85 16, 17b, 25 19 4.61 (d) 78.37 17b, 20 15, 17, 18, 20, 21 20 6.44 (s).sup. 132.69 19 19, 21 21 6.46 (s).sup. 137.86 22 22 150.95 21, 23 23 5.88 (d) 120.41 22-Me 21, 22, 24, 22-Me 24 168.77 22-Me, 23.sup. 25a 1.87 (d) 34.17 26 18, 26 25b 1.61 (d) 26 26 1.24 (m) 29.02 25, 27, 28 25, 27 27a 1.23 (m) 22.16 26, 28 26, 28, 29, 30 27b 1.27 (m) 26, 28 26, 28, 29, 30 28a 1.24 (m) 31.2 27, 29 30 28b 1.22 (m) 27, 29, 30 29a 1.27 (m) 21.31 27, 28, 30 29b 1.23 (m) 27, 28, 30 30 0.86 (t) 13.00 29a 27, 28, 29 4-me 1.09 (dd) 13.99 4 3, 4, 5 8-me 1.76 (s).sup. 11.61 6 7, 8, 9 12-me 0.79 (t) 16.69 12 11, 12, 13 22-me 2.27 (s).sup. 13.27 21, 23 20, 21, 22, 23, 24 .sup.1 171.97 2, 3 .sup.2 2.61 (m) 29.76 1, 3, 4 .sup.3 2.58 (t) 28.51 2, 3, 4 .sup.4 174.54 2, 3 1-ME 2.27 (s).sup. 51.05 2 1, 2

[0127] As shown from the data of Table 5 and FIG. 7A, the chemical structure of F61 was identified as reveromycin E.

[0128] NMR data of F71 are summarized in Table 6 below.

TABLE-US-00006 TABLE 6 position H C COSY HMBC 1 168.87 2, 3, 1-ME 2 5.82 (dt) 121.25 3, 4 1, 4, 5, 1-ME 3 6.98 (dd) 151.27 2, 4 1, 2, 4, 5, 4-Me 4 2.53 (q) 42.89 3, 5 2, 3, 5, 4-Me 5 4.07 (q) 75.68 4, 6, 7, 4-Me 4, 6, 7, 4-Me 6 5.52 (m) 126.52 4, 5, 7 5, 7, 8 7 6.25 (dd) 136.3 5, 6 5, 6, 8, 8-Me 8 140.36 9, 10, 8-Me 9 5.55 (d) 126.41 7, 10a 8, 10, 8-Me 10a 2.38 (dt) 31.57 9, 11 8, 9, 11, 8-Me 10b 1.83 (d) 11 3.46 (dt) 74.87 10a, 12 9, 10 12 1.42 (dd) 33.38 11, 13, 12-Me 10a, 11, 13 13a 1.48 (m) 27.37 14a 11, 12, 14, 15 13b 1.53 (dd) 14a 1.74 (d) 35.5 13a 14b 1.45 (d) 13, 15, 16 15 95.66 14, 16, 17 16a 1.83 (d) 31.36 17 14, 15, 17, 18 16b 1.60 (d) 17 15, 17, 18 17a 2.02 (m) 24.04 16ab, 17b 15 17b 2.34 (t) 16ab, 19 18, 19, 20 18 82.85 16, 17b, 25 19 4.61 (d) 78.37 17b, 20 15, 17, 18, 20, 21 20 6.44 (s).sup. 132.69 19 19, 21 21 6.46 (s).sup. 137.86 22 22 150.95 21, 23 23 5.88 (d) 120.41 22-Me 21, 22, 24, 22-Me 24 168.77 22-Me, 23.sup. 25a 1.87 (d) 34.17 26 18, 26 25b 1.61 (d) 26 26 1.24 (m) 29.02 25, 27, 28 25, 27 27a 1.23 (m) 22.16 26, 28 26, 28, 29, 30 27b 1.27 (m) 26, 28 26, 28, 29, 30 28a 1.24 (m) 31.2 27, 29 30 28b 1.22 (m) 27, 29, 30 29a 1.27 (m) 21.31 27, 28, 30 29b 1.23 (m) 27, 28, 30 30 0.86 (t) 13.00 29a 27, 28, 29 4-me 1.09 (dd) 13.99 4 3, 4, 5 8-me 1.76 (s).sup. 11.61 6 7, 8, 9 12-me 0.79 (t) 16.69 12 11, 12, 13 22-me 2.27 (s).sup. 13.27 21, 23 20, 21, 22, 23, 24 .sup.1 171.97 2, 3 .sup.2 2.61 (m) 29.76 1, 3, 4 .sup.3 2.58 (t) 28.51 2, 3, 4 .sup.4 174.54 2, 3 1-ME 2.27 (s).sup. 51.05 2 1, 2

[0129] As shown in Table 6 and FIG. 7B, the molecular weight and formula of F71 were the same as those of the previously known reveromycin E 4-methyl ester, but the NMR data analysis of various modes indicated that it is reveromycin E 1-methyl ester, which has a methyl group attached to the 1-COOH group. This is the first reported substance.

Example 6. In Vitro Assay for Antifungal Activity of Streptomyces sp. JCK-6141 Ethyl Acetate Fraction Against Various Plant Pathogens

[0130] 6-1. Pour-Plating Method

[0131] A pour-plating method was used to observe the inhibitory effect of Streptomyces sp. JCK-6141 strain culture containing the active antifungal substance reveromycin E against the mycelial growth of 21 species of plant pathogenic fungi (16 species) and oocytes (5 species). Briefly, PDA (potato dextrose agar) plates were treated with predetermined concentrations (0 g/ml, 1 g/ml, and 5 g/ml) of the ethyl acetate fraction of a Streptomyces sp. JCK-6141 strain culture. The centers of the plates were inoculated with the pathogenic fungi and oomycetes listed in Table 7, including Athelida rolfsii, Botryoshpaeria dothidea, Colletotrichum caudatum, Colletotrichum cocodes, Colletotrichum horii, Curvularia lunata, Endothia parasitica, Fusarium fugikuroi, Fusarium graminearum, Gaeumannomyces graminis, Pseudocerocospora circumcissa, Raffaelea quercus-mongolicae, Rhizoctonia solani, Rhizoctonia cerealis, Sclerotinia homoeocarpa, Valsa ceratosperma, Phytophthora capsici, Phytophthora cambivora, Phytophthora cinnamomi, Phythium graminicola, and Phythium ultimum, which were then incubated at 25 C. under the monitoring of mycelial growth.

TABLE-US-00007 TABLE 7 No. Type Strain Name 1 Fungus Athelida rolfsii 2 Fungus Botryoshpaeria dothidea 3 Fungus Colletotrichum caudatum 4 Fungus Colletotrichum cocodes 5 Fungus Colletotrichum horii 6 Fungus Curvularia lunata 7 Fungus Endothia parasitica 8 Fungus Fusarium fugikuroi 9 Fungus Fusarium graminearum 10 Fungus Gaeumannomyces graminis 11 Fungus Pseudocerocospora circumcissa 12 Fungus Raffaelea quercus-mongolicae 13 Fungus Rhizoctonia solani 14 Fungus Rhizoctonia cerealis 15 Fungus Sclerotinia homoeocarpa 16 Fungus Valsa ceratosperma 17 Oomycete Phytophthora capsici 18 Oomycete Phytophthora cambivora 19 Oomycete Phytophthora cinnamomi 20 Oomycete Phythium graminicola 21 Oomycete Phythium ultimum

[0132] As shown in FIG. 8, the ethyl acetate fraction of Streptomyces sp. JCK-6141 strain culture had the effect of inhibiting the mycelial growth of the plant pathogenic fungi and oomycetes listed in Table 7. In particular, the acetate fraction of Streptomyces sp. JCK-6141 strain culture inhibited the mycelial growth of all phytopathogenic fungi and oomycetes in the case of 5 g/ml treatment group. These data indicate that the ethyl acetate fraction of Streptomyces sp. JCK-6141 strain culture exhibited excellent antifungal activity.

[0133] 6-2. 96-Well Microplate Method

[0134] The minimum inhibitory concentration of active antifungal substance reveromycin E (F61) (C.sub.38H.sub.56O.sub.11), which was isolated and identified in Example 5, was measured against the mycelial growth of phytopathogenic fungi. First, reveromycin E (F61) was applied at a concentration of 0.0244 to 3.125 g/ml to mycelia of the phytopathogens listed in Table 8, including Botryoshpaeria dothidea, Botryritis cinerea, Colletotrichum horii, Curvularia lunata, Endothia parasitica, Fusarium graminearum, Fusarium oxysporum f. sp. raphanin, Fusarium oxysporum f. sp. cucumerinum, Gaeumannomyces graminis, Magnaporthiopsis poae, Magnapothe oryzae, Phythium ultimum, Rhizoctonia solani, Sclerotinia homoeocarpa, Valsa ceratosperma, Phytophthora cactorum, Phytophthora cambivora, and Phytophthora cinnamomi.

TABLE-US-00008 TABLE 8 No. Type Strain Name 1 Fungus Botryoshpaeria dothidea 2 Fungus Botryritis cinerea 3 Fungus Colletotrichum horii 4 Fungus Curvularia lunata 5 Fungus Endothia parasitica 6 Fungus Fusarium graminearum 7 Fungus Fusarium oxysporum f. sp. raphanin 8 Fungus Fusarium oxysporum f. sp. cucumerinum 9 Fungus Gaeumannomyces graminis 10 Fungus Magnaporthiopsis poae 11 Fungus Magnapothe oryzae 12 Fungus Phythium ultimum 13 Fungus Rhizoctonia solani 14 Fungus Sclerotinia homoeocarpa 15 Fungus Valsa ceratosperma 16 Oomycete Phytophthora cactorum 17 Oomycete Phytophthora cambivora 18 Oomycete Phytophthora cinnamomi

[0135] The strains listed in Table 8 were stationarily cultured at 25 C. for 7 days in PDA (Potato Dextrose Agar) plates. The mycelia thus obtained were adjusted into a concentration of 500 g/ml (w/v) and then ground using a blender (DBIHAN, HG-15D).

[0136] The ground mycelia were added 180 l to each well of 96-well plates, and then 20 l of the sample was dispensed to form a concentration of 3.125 g/ml. Subsequently, 100 L taken from the well where a concentration of 3.125 g/ml had been prepared was mixed with 100 l of the ground mycelia in a neighbor well to form a concentration of 1.56 g/ml. The dilution was repeated in such a serial manner to prepare concentrations of 0.78 to 0.0224 g/ml. After incubation for 24 hours at 25 C., degrees of mycelial growth were measured, and for each group, the experiment was performed in triplicate. The results are shown in Table 9 below.

TABLE-US-00009 TABLE 9 No. Type Strain Name F61 (g/ml) 1 Fungus Botryoshpaeria dothidea 0.098 2 Fungus Botryritis cinerea 1.56 3 Fungus Colletotrichum horii 0.049 4 Fungus Curvularia lunata 0.78 5 Fungus Endothia parasitica 1.56 6 Fungus Fusarium graminearum 0.195 7 Fungus Fusarium oxysporum f. sp. raphani 1.56 8 Fungus Fusarium oxysporum f. sp. 1.56 cucumerinum 9 Fungus Gaeumannomyces graminis 3.125 10 Fungus Magnaporthiopsis poae 0.0244 11 Fungus Magnapothe oryzae 0.78 12 Fungus Phythium ultimum 1.56 13 Fungus Rhizoctonia solani 1.56 14 Fungus Sclerotinia homoeocarpa 0.195 15 Fungus Valsa ceratosperma 0.78 16 Oomycete Phytophthora cactorum 0.195 17 Oomycete Phytophthora cambivora 0.195 18 Oomycete Phytophthora cinnamomi 0.39

[0137] As shown in Table 9, reveromycin E (F61) exhibited potent antifungal activity to inhibit the mycelial growth of various plant pathogens. Although slightly differing in the concentration of 100% growth inhibition from one pathogen to another, reveromycin E exhibited excellent antifungal activity against the pathogens, ranging in MIC value from 0.0224 to 3.125 g/ml. In particular, the substance exhibits excellent antifungal activity against the oomycetes Phytophthora cactorum, Phytophthora cambivora and Phytophthora cinnamomi for which MIC values were measured to range from 0.195 to 0.39 g/ml.

[0138] Usually, Fusarium strains are more resistant to chemicals than other species. However, reveromycine E (F61) exhibited very high antifungal activity against fungi such as Fusarium graminearum and Fusarium graminearum, with MIC values therefor ranging from 1.56 and 0.195 g/ml, respectively.

Example 7. Assay for Lytic Enzyme Activity of Streptomyces sp. JCK-6141 Strain Culture

[0139] In order to assay the lytic enzyme activity of Streptomyces sp. JCK-6141 strain culture, the activity of the lytic enzymes protease, chitinase, and cellulase were measured. Strains having lytic enzyme activity are known to be high in chitinase activity. This characteristic confirms inhibitory activity against fungi.

[0140] For use in an assay for protease activity, agar was added to 1% skim milk to make a plate onto which Streptomyces sp. JCK-6141 strain was then inoculated. After inoculation, the plate was stationarily incubated at 30 C. Two days after incubation, the clear zone by protease activity was observed. For chitinase activity, Streptomyces sp. JCK-6141 strain was inoculated onto PDA (Potato Dextrose Agar) plates containing 1.5% colloidal chitin and then stationarily incubated at 28 C. for one week to create a clear zone thereon. Cellulase enzyme activity was measured by culturing Streptomyces sp. JCK-6141 strain in Mendel-Leeds agar plates using carboxymethyl cellulose (CMC) as the sole carbon source. Plate containing 0.4 g/L KH.sub.2PO.sub.4, 0.02 g/L CaCl.sub.2), 0.02 g/L NaCl, 0.02 g/L FeSO.sub.47H.sub.2O, 2.5 g/L CMC, and 15.0 g/L agar was adjusted with 1 M NaOH to have a pH of 7.2. Streptomyces sp. JCK-6141 strain was inoculated onto the plate and stationarily incubated 28 C. for one week while cellulase release was monitored. The activity of each protease, chitinase, and cellulase was measured, and the results are summarized in Table 10 below.

TABLE-US-00010 TABLE 10 Sample Protease activity Chitinase Activity Cellulase activity JCK-6141 + +++

[0141] As shown in Table 10, it was confirmed that Streptomyces sp. JCK-6141 strain not only had chitinase activity, but, in particular, possessed excellent cellulase activity. Oomycete cell walls contain cellulose, and other fungi contain chitin as a cell wall component. Therefore, through the measurement of cellulase and chitinase activities of Streptomyces sp. JCK-6141 strain, it can be revealed whether Streptomyces sp. JCK-6141 strain has higher antimicrobial activity against oomycetes or fungi. Previously, the results of Example 6-2 demonstrated that treatment with reveromycin E (F61) had higher inhibitory activity against mycelial growth of phytopathogenic oomycetes than phytopathogenic fungi. As such, the culture of Streptomyces sp. JCK-6141 strain possesses chitinase and cellulase activity as well as the low-molecular weight active antimicrobial material reveromycin E (F61), thereby exhibiting excellent antimicrobial activity against various phytopathogenic fungi and oocytes.

Example 8. In Vivo Assay for Controlling Effect of Streptomyces sp. JCK-6141 Strain on Damping-Off in Cucumber

[0142] 8-1. Plant Preparation

[0143] Nebakja cucumber seeds (Syngenta, Korea), a sensitive cultivar of cucumber, were germinated for two days at 25 C. on filter paper (Petri dish with 9 cm diameter) soaked in sterile water and then grown for 5 days to prepare plants (5-day-old cucumber seedlings), performing a pot experiment for an in vivo biocontrol of damping-off in cucumbers by JCK-6141 strain.

[0144] 8-2. Sample Application and Inoculation

[0145] A total of four samples to be applied to the plants by soil drenching were prepared by diluting Streptomyces sp. JCK-6141 strain culture 100-fold and 10-fold with distilled water and fractionating the dilutions with ethyl acetate to final concentrations of 50 g/ml and 200 g/ml.

[0146] Rhizoctonia solani (hereinafter referred to as Rs), which causes damping-off in cucumbers, was prepared as an inoculum to be inoculated into the plant. Agar covered with active-grown Rs mycelia was cut and inoculated into a 250 ml Erlenmeyer flask containing 100 mL of PDB (potato dextrose broth). After incubation of the flask at 28 C. for 4 days with shaking at 150 rpm, the cultured mycelia were filtered through 4-layer gauze and washed with sterile water. The soil for Rs mycelial inoculation was prepared by mixing 0.75 g of Rs mycelia per 1 kg of the gardening soil mix.

[0147] Five days after the germination, the soil in which cucumber seedlings were planted was drenched with 10 ml of each of the four samples. After one day of soil drenching, the soil for Rs mycelium inoculation was aliquoted into 150 g per pot and inoculated with cucumber seedlings to prepare 1 DBI. 1 DBI could reveal the preventive effect of Streptomyces sp. JCK-6141 on damping-off in cucumbers because the sample was pre-treated before inoculation.

[0148] The soil for Rs mycelium inoculation was aliquoted into 150 g per pot. After 5 days of germination, cucumber seedlings were transplanted, and after 1 hour, 1 HAI was prepared by drenching the seedlings with 10 ml of each of the four samples. 1 HAI can confirm the therapeutic effect because the sample was drenched after transplanting the seedlings into the soil mixed with Rs mycelium.

[0149] For a non-treated group, a solution added with Tween 20 (concentration 250 g/ml) was used, and as a control drug, a dispersive solution of Janrokend (active ingredient Hymexazole 30%, Penthiopyrad 5%, Korea Ginseng Corporation, Korea) was diluted 1000-fold and applied. All treatments were carried out in a soil drenching manner with 10 ml per pot.

[0150] 8-3. In Vivo Bioassay

[0151] Cucumber seedlings transplanted into Rs mycelium-inoculated pots were grown at 25 C. for 7 days and then harvested to count diseased plants. Each treatment was repeated with triple replicates, and a replicate consisted of 10 pots. The experiment was conducted with two replicates to verify the efficacy. The disease control value was calculated using Equation 1 below, and the results of 1 DBI and 1 HAI are summarized in Tables 11 and 12, below.

[00001]$\mathrm{Control}\mathrm{value}\left(\%\right)=\left(1-\frac{\mathrm{Disease}\mathrm{incidence}\mathrm{of}\mathrm{treated}\mathrm{group}}{\mathrm{Disease}\mathrm{incidence}\mathrm{of}\mathrm{non}-\mathrm{treated}\mathrm{group}}\right)100$

TABLE-US-00011 TABLE 11 Concentration Control value Treated group (1 DBI) (fold, g/ml) (%) CB (diluted in distilled water) 100-fold 96.2 8.3 10-fold 92.0 16.6 EtOAc ext 50 g/ml 0.0 0.0 200 g/ml 50.3 57.7 Janrokend 1000-fold 100 0.0

TABLE-US-00012 TABLE 12 Treated group Concentration Control value (1 HAI) (fold, g/ml) (%) CB (diluted in distilled water) 100-fold 75.0 50.0 10-fold 100 0.0 EtOAc Ext 50 g/ml 75.0 50.0 200 g/ml 100 0.0 Janrokend 1000-fold 100 0.0

[0152] As shown in Tables 11 and 12, and FIGS. 9A to 10B, the culture of Streptomyces sp. JCK-6141 strain reduced the incidence of Rs-caused damping-off in cucumbers, and the 100-fold and 10-fold dilutions thereof exhibited control effects similar to that of the control drug Janrokend irrespective of the sample application time. In particular, the application of a 10-fold dilution of the culture gave a control value of 100% for 1 HAI, which was similar measurement to the control value using the control agent. The ethyl acetate fraction showed control activity in a dose-dependent manner. Specifically, when the ethyl acetate fraction was applied in amounts of 50 g/ml and 200 g/ml to 1 HAI, the control values were about 75.0% and 100%, respectively. The data indicated that the diluted culture and ethyl acetate fractions of the culture of Streptomyces sp. JCK-6141 strain had excellent antifungal activity against Rhizoctonia solani, a causative pathogen of cucumbers damping-off.

Example 9. In Vivo Assay for Controlling Effect of Streptomyces sp. JCK-6141 Strain on Fusarium Wilt in Cucumber

[0153] 9-1. Plant Preparation

[0154] The control efficacy of Streptomyces sp. JCK-6141 strain against Fusarium wilt was evaluated in vivo. Horticultural gardening soil No. 5 (Punong Sangtosa, Korea) was put into 88 pots (15 ml/pot, Bumnong Co. Ltd., Korea), and one seed of the cucumber species Jungboksamcheok (Syngenta, Korea) was sown per pot and cultivated in a greenhouse for 7 days to prepare plants to be used for the control effect evaluation.

[0155] 9-2. Sample Treatment

[0156] Fusarium oxysporum f. sp. cucumerinum (Foc) was inoculated into PDA plates and cultured at 25 C. for 7 days. From the cultured plate, mycelial fragments of Foc were removed and then were inoculated into V8 broth (V-8 juice 200 ml, CaCO.sub.3 3 g, distilled water 1 L) and cultured at 25 C. in a dark condition for 7 days with shaking at 150 rpm. After shaking the culture, the pathogen culture was harvested and filtered through quadruple gauze to remove mycelia, followed by centrifugation (5000 rpm, 10 minutes, 4 C.). The spore pellet obtained by removing the supernatant was added with sterile water and suspended. For use as an inoculum, the Foc spore suspension was diluted with sterile water under an optical microscope to give a spore (conidium) concentration of 1.010.sup.7 conidia/ml as countered by a hemacytometer.

[0157] 9-3. In Vivo Bioassay

[0158] After being transplanted at a density of one seed per pot, pregerminated cucumber seeds were grown at 25 C. into cucumber seedlings which were then treated with the sample in three ways 5 days later. The culture of Streptomyces sp. JCK-6141 strain was diluted 100-fold and 10-fold with distilled water, and fractionated with ethyl acetate to final concentrations of 50 g/ml and 200 g/ml to prepare a total of four samples.

[0159] The each samples prepared from Streptomyces sp. JCK-6141 strain was applied in 10 ml to 5 days-old cucumber seedlings through soil drenching. One day after the soil drenching treatment of Streptomyces sp. JCK-6141 strain sample, the treated group was inoculated with 10 ml of the spore suspension of the Foc strain to prepare 1 DBI. In addition, 5 days-old cucumber seedlings were inoculated with 10 ml of the spore suspension of Foc strain by soil drench. One hour after inoculation, 10 ml of the Streptomyces sp. JCK-6141 strain sample was applied to seedlings by soil drenching to prepare 1 HAI.

[0160] For a non-treated group, a solution added with Tween 20 (concentration 250 g/ml) was applied, and as a control drug, a dispersive solution of Janrokend (active ingredient Hymexazole 30%, Penthiopyrad 5%, Korea Ginseng Corporation, Korea) was diluted 1000-fold and applied. All treatments were carried out in soil drenching manner with 10 ml per pot.

[0161] The inoculated cucumber seedlings were cultured in a humid room at 25 C. for 24 hours, then transferred to a constant temperature room of 25 C., irradiated with light for 12 hours a day, and grown for 3 weeks. Each treatment was repeated with triple replicates, and a replicate consisted of 10 pots. The experiment was conducted with two replicates to verify the efficacy of the treatment. The disease control value was calculated using Equation 1 and the results are summarized in Tables 13 and 14, below.

TABLE-US-00013 TABLE 13 Treated group Concentration Control value (1 DBI) (fold, g/ml) (%) CB 100-fold 40.8 13.2 10-fold 67.1 13.2 EtOAc Ext 50 g/ml 100.0 0.0 200 g/ml 28.6 35.0 Janrokend 1000 fold 100.0 0.0

TABLE-US-00014 TABLE 14 Treated group Concentration Control value (1 HAI) (fold, g/ml) (%) CB 100-fold 19.7 19.9 10-fold 35.5 46.0 EtOAc Ext 50 g/ml 40.8 13.2 200 g/ml 23.7 27.3 Janrokend 1000-fold 42.1 43.2

[0162] As shown in Tables 13 and 14, and FIGS. 11A to 12B, the Streptomyces sp. JCK-6141 strain samples reduced the incidence of Foc-caused Fusarium wilt in cucumbers and exhibited control efficacy similar to or higher than that of the control drug Janrokend irrespective of the sample application time. In particular, the application of 50 g/ml of the ethylacetate fraction gave a control value of 100% for 1 DBI, exhibiting the highest control performance. In addition, when applied to 1 DBI and 1 HAI, the ethylacetate fraction showed higher control activity at a low concentration (50 g/ml) than at a high concentration (200 g/ml), indicating that Fusarium wilt can be effectively controlled not only by the direct antifungal activity of the reveromycin substances but also by inducible resistance mechanism of these or other substances.

Example 10. In Vivo Assay for Controlling Effect of Streptomyces sp. JCK-6141 Strain on Rice Sheath Blight

[0163] The control efficacy of Streptomyces sp. JCK-6141 strain against rice sheath blight (RSB) was examined in vivo. As an experimental plant, the rice cultivar Nakdong (Oryza sativa L.) was used.

[0164] One day before pathogen inoculation, the Nakdong rice plants were treated by soil drenching with 10 ml of each of the 3-fold and 9-fold dilutions of the Streptomyces sp. JCK-6141 strain culture in distilled water. After putting an appropriate amount of Nakdong rice bran treated with the dilutions was put into a 1-L culture bottle and sterilized, followed by evenly inoculating finely ground mycelial mass of cultured Rhizoctonia solani into the pots where the rice plants had been grown. After inoculation, incubation was carried out for 3 days in a humid chamber (25 C.) and then for 4 days in an incubator with a relative humidity of 80%. Examination was made of the onset of the disease. As a control, the synthetic chemical fungicide Flutolanil was used at 20 g/ml or 50 g/ml concentration. For incidence rate, infected areas in the rice sheath were examined, and the results are summarized in Table 15, below.

TABLE-US-00015 TABLE 15 Concentration RSB Control Treated group (fold, g/ml) (%) JCK-6164 Culture broth 3-fold 35.0 5.0 b (CB) 9-fold 15.0 5.0 c Chemical fungicide 50 g/ml 100.0 0.0 a (Flutolanil) 20 g/ml 100.0 0.0 a

[0165] As shown in Table 15 and FIG. 13, the 3-fold dilution of Streptomyces sp. JCK-6141 strain culture exhibited a control activity of 35.0% against rice sheath blight and, although lower in control value than the 3-fold dilution, the 9-fold dilution of the culture exhibited a control activity of 15.0%. These data imply that, although low in control efficacy compared to the synthetic chemical fungicide Flutolanil, Streptomyces sp. JCK-6141 strain culture can effectively control rice sheath blight, with a control value of 35.0%.

Example 11. In Vivo Assay for Controlling Effect of Streptomyces sp. JCK-6141 Strain on Wheat Leaf Rust

[0166] The control efficacy of Streptomyces sp. JCK-6141 strain on wheat leaf rust was examined in vivo. As an experimental plant, the wheat cultivar Eunpa (Triticum aestivum L.) was used.

[0167] One day before pathogen inoculation, the Eunpa wheat plants were treated by soil drenching with 10 ml of each of the 3-fold and 9-fold dilutions of the Streptomyces sp. JCK-6141 strain culture in distilled water. Since the pathogen Puccinia recondite is an obligate biotroph, uredospores formed on wheat seedlings as a result of passages of the plant in the laboratory were used as an inoculum. A uredospore suspension (spore 0.67 g/L) was prepared and sprayed over the wheat seedlings, which were then incubated at 20 C. for one day in a humid room and subsequently in an incubator with a relative moisture of 70% to induce the onset of the disease. As a control, the synthetic chemical fungicide Flutolanil was used at 20 g/ml or 50 g/ml concentration. For incidence rate, infected areas in the rice sheath were examined 7 days after inoculation, and the results are summarized in Table 16, below.

TABLE-US-00016 TABLE 16 Concentration RSB Control Treated group (fold, g/ml) (%) JCK-6164 3-fold 80.0 0.0 b culture broth (CB) 9-fold 13.3 6.7 c Chemical fungicide 50 g/ml 100.0 0.0 a (Flutolanil) 20 g/ml 73.3 6.7 b

[0168] As shown in Table 16 and FIG. 14, the 3-fold dilution of Streptomyces sp. JCK-6141 strain culture exhibited a control efficacy of 80.0% against wheat leaf rust and, although lower in control value than the 3-fold dilution, the 9-fold dilution of the culture exhibited a control activity of 13.3%. These data imply that, although low in control efficacy compared to the synthetic chemical fungicide Flutolanil, Streptomyces sp. JCK-6141 strain culture effectively controls wheat leaf rust, with a control value of 80.0%.

Example 12. In Vivo Assay for Controlling Effect of Streptomyces sp. JCK-6141 Strain on Fusarium Head Blight

[0169] The control efficacy of Streptomyces sp. JCK-6141 strain on Fusarium head blight was examined in vivo. As an experimental plant, the wheat cultivar Eunpa (Triticum aestivum L.) was used.

[0170] First, Streptomyces sp. JCK-6141 strain was inoculated into a sterile TSB broth and then cultured at 30 C. for 3 days with shaking at 150 rpm, to prepare a culture. Each of the 5- and 20-fold dilutions of the Streptomyces sp. JCK-6141 strain culture in distilled water was sprayed over ears of wheat, then left for 2 hours. The plants were inoculated with a spore suspension of Fusarium graminearum, which is a pathogen causing Fusarium head blight, and the entire pot was covered with a vinyl sheet to maintain humidity for 3 days. The sample was applied to the plants when the ears flowered. As a positive control, a synthetic pesticide Almuri (2000-fold dilution, Syngenta, Switzerland) was applied while Tween-20 (500 g/ml) was used as a negative control. Ten ears of wheat were treated three times as a basic unit. The disease severity and incidence rate were examined 2 weeks after inoculation, and the results are summarized in Table 17 below.

TABLE-US-00017 TABLE 17 Disease severity Incidence FHB index rate Index Control Inhibitor Conc. (%) (%) (%) (%) Almuri 2000-fold 17.0 75.1 12.8 86.3 JCK-6141 5-fold 49.2 100.0 49.2 47.2 culture 20-fold 67.1 100.0 67.1 28.0 Inhibitor-free 93.2 100.0 93.2 0.0 control

[0171] As shown in Table 17 and FIG. 15, the 5-fold dilution of Streptomyces sp. JCK-6141 strain culture exhibited a control activity of 47.2% against Fusarium head blight and, although lower in control value than the 3-fold dilution, the 20-fold dilution of the culture exhibited a control value of 28.0%. These data imply that Streptomyces sp. JCK-6141 strain culture, although low in control effect compared to the synthetic chemical fungicide Almuri, is effective for controlling Fusarium head blight, with a control effect amounting to 47.2%.

Example 13. In Vivo Assay for Controlling Effect of Streptomyces sp. JCK-6141 Strain on Dollar Spot Disease

[0172] The control efficacy of Streptomyces sp. JCK-6141 strain against dollar spot disease was evaluated in vivo.

[0173] 13-1. Plant Preparation

[0174] As an experimental plant, seeds of creeping bentgrass (Agrostis palustris), which is a type of cool-season grass, were used. In a pot with a diameter of 7 cm and a height of 6 cm, sterilized sand and horticultural gardening soil were mixed at a ratio of 3:1. The seeds were sown and grown for 30 days before use in experiments.

[0175] 13-2. Sample Treatment

[0176] After diluting Streptomyces sp. JCK-6141 strain culture 3- and 9-fold with distilled water, Tween-20 (250 g/ml) was added thereto, and then 10 ml per pot was applied by soil drenching 1 day before inoculation with the pathogen. An untreated group was treated with Tween-20 (250 g/ml) solution while as a control agent, a Horikuo (active ingredient tebuconazole, 25% by weight) emulsion, commercially available for prevention of grass fungus, was diluted 2000-fold and applied by soil drenching to the pots in an amount of 10 ml per pot one day before inoculation. The pathogen Sclerotinia homoeocarpa was cultured on PDA (potato dextrose agar) plates for 5 days. The colonies thus formed were cut into pieces, each 1 cm wide and 1 cm long. For use as an inoculum, five pieces were added into each wheat bran-rice husk medium (36 g of wheat bran, 6 g of rice husk, and 40 ml of distilled water in 1 L Erlenmeyer flask) and then cultured for 7 days in a 25 C. incubator. After incubation, 400 ml of sterile water (including 200 g/ml of Streptomycin sulfate) was added. The mixture was ground using a blender and then applied by soil drenching with 4 ml per pot. The treated turfgrass was placed under 25 C. and 95% relative humidity to develop the disease for 7 days. The disease severity was examined, and the results are summarized in Table 18, below.

TABLE-US-00018 TABLE 18 Concentration Control value Treated group (fold) (%) CB (dilution in distilled water) 3-fold 76.3 16.5 9-fold 51.5 11.0 Horikuo 2000-fold 89.3 5.3

[0177] As shown in Table 18 and FIGS. 16A and 16B, the 3-fold dilution of Streptomyces sp. JCK-6141 strain culture exhibited a control activity of 76% against dollar spot disease, and the 9-fold diluted culture exhibited a control activity of 76%. These data imply that the Streptomyces sp. JCK-6141 strain culture, although low in control effect compared to the synthetic chemical fungicide Horikuo, is effective for controlling dollar spot disease, with a control effect amounting to 76%.

INDUSTRIAL APPLICABILITY

[0178] The present disclosure relates to a composition including a culture of Streptomyces sp. JCK-6141 or an extract from the culture for controlling plant diseases, a method for producing the same, and a method for controlling plant diseases and, more particularly, to a controlling efficacy identified in a culture of Streptomyces sp. JCK-6141 having an antimicrobial activity or an extract from the culture against phytopathogens.