• Current Research on Agriculture and Life Sciences
• /
• v.7
• /
• pp.33-40
• /
• 1989

In order to elucidate the antifungal activity of prochloraz(imidazole) and triadimefon(triazole), the mycelia of the Valsa ceratosperma were treated with the compounds in vitro. Prochloraz applied to the target pathogen inhibited mycelial growth more than triadimefon. The concentration for the 50% inhibition of mycelial growth ($I_{50}$) was 1-5 ppm in treatment of prochloraz and 5-10 ppm in treatment of triadimefon. The mycelia of Valsa ceratosperma treated with low concentration of prochloraz and triadimefon were morphologically abnormal as observed with an optical microscope. Content of total lipid and fatty acids were not changed by the treatments of prochloraz and triadimefon, respectively, in liquid medium.

• Korean Journal of Organic Agriculture
• /
• v.23 no.4
• /
• pp.887-896
• /
• 2015

To develop environment-friendly agricultural products with anti-microbial activity against Sclerotinia sclerotiorum as a pathogen of sclerotium disease, Usnea longissima was extracted by methanol and its extract was fractionated into several solvent fractions. The chloroform fraction, which showed the highest antimicrobial activity, was separated by silica gel-column chromatography and obtained into nine group subfractions. The nine group fractions were searched the antifungal activities by bioassay. The most active No. 3 subfraction was analyzed by GC-MS. Each mass spectra, corresponding to each peak of chromatogram, was compared to database of Wiley library. As a result, Usnic acid was identified as main compounds. In conclusion, Usnic acid isolated from Usnea longissima was antimicrobial chemical against Sclerotinia sclerotiorum as a pathogen of sclerotium disease.

• Mycobiology
• /
• v.35 no.4
• /
• pp.210-214
• /
• 2007

Antibacterial and antifungal activities of liquid culture filtrate, water and ethanol extract (solid culture) of Stereum ostrea were evaluated against 5 bacteria and 3 plant pathogenic fungi. To determine the minimal inhibitory concentration (MIC), we studied $5{\sim}300\;mg/ml$ concentrations against bacteria and fungi separately. The MIC was 10 mg/ml for Bacillus subtilis and 40 mg/ml for Colletotrichum gloeosporioides and Colletotrichum miyabeanus. Liquid culture filtrate was more effective against Gram positive than Gram negative bacteria, and Staphylococcus aureus was the most inhibited (20.3 mm) bacterium. Water and ethanol extracts were effective against both Gram positive and Gram negative bacteria, and water extract was better than ethanol extract. In water and ethanol extract, inhibition zones were 23.6 and 21.0 mm (S. aureus) and 26.3 and 22.3 mm (Pseudomonas aeruginosa), respectively. For plant pathogenic fungi, the highest and lowest percent inhibition of mycelial growth (PIMG) was found 82.8 and 14.4 against C. miyabeanus and Botrytis cinerea in liquid culture filtrate, respectively. In water extract, the PIMG was found to be the highest 85.2 and lowest 41.7 for C. miyabeanus and C. gloeosporioides, respectively. The inhibitory effect of ethanol extract was better against C. miyabeanus than C. gloeosporioides and B. cinerea. Among 3 samples, water extract was the best against tested pathogenic fungi. This study offers that the extracts isolated from S. ostrea contain potential compounds which inhibit the growth of both bacteria and fungi.

• The Plant Pathology Journal
• /
• v.31 no.2
• /
• pp.165-175
• /
• 2015

Anthracnose is a fungal disease caused by Colletotrichum species that is detrimental to numerous plant species. Anthracnose control with fungicides has both human health and environmental safety implications. Despite increasing public concerns, fungicide use will continue in the absence of viable alternatives. There have been relatively less efforts to search antagonistic bacteria from mudflats harboring microbial diversity. A total of 420 bacterial strains were isolated from mudflats near the western sea of South Korea. Five bacterial strains, LB01, LB14, HM03, HM17, and LB15, were characterized as having antifungal properties in the presence of C. acutatum and C. gloeosporioides. The three Bacillus atrophaeus strains, LB14, HM03, and HM17, produced large quantities of chitinase and protease enzymes, whereas the B. amyloliquefaciens strain LB01 produced protease and cellulase enzymes. Two important antagonistic traits, siderophore production and solubilization of insoluble phosphate, were observed in the three B. atrophaeus strains. Analyses of disease suppression revealed that LB14 was most effective for suppressing the incidence of anthracnose symptoms on pepper fruits. LB14 produced antagonistic compounds and suppressed conidial germination of C. acutatum and C. gloeosporioides. The results from the present study will provide a basis for developing a reliable alternative to fungicides for anthracnose control.

• Advances in Traditional Medicine
• /
• v.3 no.3
• /
• pp.111-122
• /
• 2003

Plants of the genus Hypericum (Family - Hypericaceae) are herbs, shrubs or small trees and are distributed chiefly in the temperate regions of the world. About 400 different species of Hypericum are available throughout the globe and 20 species occur in India, including a few cultivated in gardens. Almost all plants of the genus Hypericum are widely used in folk medicine. Several potent phytoconstituents from different Hypericum species have led to the isolation of antibacterial, antifungal and cytotoxic compounds. With the development of resistance and cross resistance with different microorganisms and the evolution of so many deadly diseases the screening and evaluation of the phytoconstituents so much so the development of varied phytoconstituents for the drug development for these deadly diseases is utmost essential in every aspects. The present review on the antimicrobial use of different Hypericum reports the findings from and extensive literature search on the Hypericum species around the globe that have been assessed for antimicrobial and antiviral activity. An attempt has been made through this review to summarize the information in this aspect in order to highlight the promising species of this genus which are worthy for further investigation as leads for drug development. Over 31 different Hypericum species have been reported to possess such activities with their varied number of phytoconstituents. Sixteen different constituents of six different classes of phytoconstituents have been reported to be present in different varieties of Hypericum, which may be considered responsible for this activity.

• Journal of Microbiology and Biotechnology
• /
• v.32 no.4
• /
• pp.504-513
• /
• 2022

Chitin deacetylase (CDA) inhibitors were developed as novel antifungal agents because CDA participates in critical fungal physiological and metabolic processes and increases virulence in soil-borne fungal pathogens. However, few CDA inhibitors have been reported. In this study, 150 candidate CDA inhibitors were selected from the commercial Chemdiv compound library through structure-based virtual screening. The top-ranked 25 compounds were further evaluated for biological activity. The compound J075-4187 had an IC50 of 4.24 ± 0.16 µM for AnCDA. Molecular docking calculations predicted that compound J075-4187 binds to the amino acid residues, including active sites (H101, D48). Furthermore, compound J075-4187 inhibited food spoilage fungi and plant pathogenic fungi, with minimum inhibitory concentration (MIC) at 260 ㎍/ml and minimum fungicidal concentration (MFC) at 520 ㎍/ml. Therefore, compound J075-4187 is a good candidate for use in developing antifungal agents for fungi control.

• Journal of Microbiology and Biotechnology
• /
• v.32 no.7
• /
• pp.911-917
• /
• 2022

As valuable antibiotics, microbial natural products have been in use for decades in various fields. Among them are polyene compounds including nystatin, amphotericin, and nystatin-like Pseudonocardia polyenes (NPPs). Polyene macrolides are known to possess various biological effects, such as antifungal and antiviral activities. NPP A1, which is produced by Pseudonocardia autotrophica, contains a unique disaccharide moiety in the tetraene macrolide backbone. NPP B1, with a heptane structure and improved antifungal activity, was then developed via genetic manipulation of the NPP A1 biosynthetic gene cluster (BGC). Here, we generated a Streptomyces artificial chromosomal DNA library to isolate a large-sized NPP B1 BGC. The NPP B1 BGC was successfully isolated from P. autotrophica chromosome through the construction and screening of a bacterial artificial chromosome (BAC) library, even though the isolated 140-kb BAC clone (named pNPPB1s) lacked approximately 8 kb of the right-end portion of the NPP B1 BGC. The additional introduction of the pNPPB1s as well as co-expression of the 32-kb portion including the missing 8 kb led to a 7.3-fold increase in the production level of NPP B1 in P. autotrophica. The qRT-PCR confirmed that the transcription level of NPP B1 BGC was significantly increased in the P. autotrophica strain containing two copies of the NPP B1 BGCs. Interestingly, the NPP B1 exhibited a previously unidentified SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) inhibition activity in vitro. These results suggest that the Streptomyces BAC cloning of a large-sized, natural product BGC is a valuable approach for titer improvement and biological activity screening of natural products in actinomycetes.

• Research in Plant Disease
• /
• v.30 no.2
• /
• pp.189-193
• /
• 2024

Cucumber (Cucumis sativus L.) is substantial economic importance in South Korea, with its cultivation occupying a significant portion of agricultural land. However, sustainable cucumber production requires effective management of various diseases affecting the crop yield. In this study, we explored the potential of Streptomyces sp. S20-465-derived metabolites in controlling cucumber anthracnose disease caused by Colletotrichum orbiculare. This study identified 4-hydroxy-4-methyl-2-pentanone as a potent antifungal compound present in the n-hexane extract of Streptomyces sp. S20-465 culture filtrate. This compound exhibited significant the disease reduction, demonstrating their potential as control agents. Our findings suggest that Streptomyces sp. S20-465-derived metabolite could serve as an effective tool for managing cucumber anthracnose, offering a sustainable approach to enhancing cucumber production. Further research into the application and efficacy of these compounds in agricultural system will be conducted.

• Journal of Applied Biological Chemistry
• /
• v.66
• /
• pp.15-22
• /
• 2023

The aim of the present study was to evaluate the chemical composition and antioxidative activity of rhizome essential oil of Kaempferia parviflora Wall. ex Baker. The essential oil extracted by hydrodistillation was chemically profiled by GC/MS analysis. The antioxidative activity was determined and evaluated spectroscopically by the 2,2-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging assays. According to the results, the major essential oil components were camphene (18.03%), β-pinene (14.25%), a-pinene (12.38%), endo-borneol (10.23%), β-copaene (8.38%), and linalool (8.20%). K. parviflora rhizome oil possessed antioxidant potential, exhibiting DPPH and ABTS radical scavenging activities as high as 80.90 and 94.04%, respectively, at a concentration of 10 mg/mL. The corresponding IC₅₀ values were 0.451±0.051 and 0.527±0.022 mg/mL, respectively (IC₅₀ values for ascorbic acid, as the standard, were 0.209±0.016 and 0.245±0.022 mg/mL, respectively). The mycelium of F. oxysporum was distorted and collapsed when treated with 0.5 mg/mL of the EO of K. parviflora rhizome for 3 days treatment, which may provide an important information for exploring the metabolism of the fungicide K. parviflora rhizome and its derived compounds against F. oxysporum. This study provides the chemical properties of the essential oil of K. parviflora rhizome grown in Vietnam and their potential antioxidant and antifungal activities.

• The Plant Pathology Journal
• /
• v.40 no.4
• /
• pp.346-357
• /
• 2024

This study was carried out to screen the antifungal activity against Colletotrichum acutatum, Colletotrichum dematium, and Colletotrichum coccodes. Bacterial isolate GP-P8 from pepper soil was found to be effective against the tested pathogens with an average inhibition rate of 70.7% in in vitro dual culture assays. 16S rRNA gene sequencing analysis result showed that the effective bacterial isolate as Bacillus siamensis. Biochemical characterization of GP-P8 was also performed. According to the results, protease and cellulose, siderophore production, phosphate solubilization, starch hydrolysis, and indole-3-acetic acid production were shown by the GP-P8. Using specific primers, genes involved in the production of antibiotics, such as iturin, fengycin, difficidin, bacilysin, bacillibactin, surfactin, macrolactin, and bacillaene were also detected in B. siamensis GP-P8. Identification and analysis of volatile organic compounds through solid phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS) revealed that acetoin and 2,3-butanediol were produced by isolate GP-P8. In vivo tests showed that GP-P8 significantly reduced the anthracnose disease caused by C. acutatum, and enhanced the growth of pepper plant. Reverse transcription polymerase chain reaction analysis of pepper fruits revealed that GP-P8 treated pepper plants showed increased expression of immune genes such as CaPR1, CaPR4, CaNPR1, CaMAPK4, CaJA2, and CaERF53. These results strongly suggest that GP-P8 could be a promising biocontrol agent against pepper anthracnose disease and possibly a pepper plant growth-promoting agent.