• Journal of Life Science
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• v.24 no.12
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• pp.1308-1315
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• 2014

Biological control using the plant growth-promoting Rhizobacterium (PGPR) has received significant attention in recent years. PGPR has been linked with promoting growth in economically important crops, such as potatoes, tomatoes, and rice. Bacillus mojavensis KJS-3 (Moja-3), isolated from food waste, possesses antifungal properties against Aspergillus terreus, A. fumagatus, A. flavus, and Fusarium redolense, and it may have potential in the development of products for industrial applications. The main purpose of this study was to determine the effects of spraying the PGPR Bacillus mojavensis KJS-3 on the growth of altari radish (leaf number, leaf length, leaf weight, root length, and rhizome length, adjacent portion diameter, and weight) and lettuce (leaf number, length, width, and weight). Three different concentrations of the foliar spray treatment of B. mojavensis KJS-3 were applied to the altari radish and lettuce: the recommended standard concentration of $1{\times}10^9cfu/g$, half the standard concentration of $0.5{\times}10^9cfu/g$, and double the standard concentration of $2{\times}10^9cfu/g$). The B. mojavensis strain foliar spray treatment increased the growth of the leaves and roots of the altari radish and increased the growth of the lettuce leaves. For both plants, the recommended concentration of B. mojavensis KJS-3 produced better growth than half the standard concentration, and the growth was similar with the double dose. This study demonstrates positive effects of Moja-3, suggesting it may be a potential new bio-fertilizer for improving the growth of altari radish and lettuce.

• 한국균학회소식:학술대회논문집
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• 2016.05a
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• pp.13-13
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• 2016

Insects constitute the largest and most diverse group of animals in the world. They also serve as the hosts or nutrient sources for an immense assemblage of pathogens, parasites, and predators. More than 700 fungal species from 100 genera have adopted an entomopathogenic lifestyle. Although entomopathogenic fungi were studied as only biocontrol agents against a variety of pests in various countries, it has been recently focused their additional roles in nature. They are antagonists to/against plant pathogens, endophytes, and possibly even plant growth promoting agents. The potential antimicrobial effect against fungal plant pathogens by an isolate of entomopathogenic fungi including Beauveria bassiana, Lecanicillium spp., and Isaria fumosorosea have been reported since late 1990s, but wasn't reported pathogenicity of the isolate against pests. Later, a Canadian Lecanicillium sp. isolate and L. longisporium isolated from Vertalec$^{(R)}$ showed simultaneous control effect against both aphid and cucumber powder mildew. Therefore, the antimicrobial activities of 342 fungi isolates collected from various regions and conditions in Korea were evaluated against plant pathogenic fungus Botrytis cinerea using dual culture technique on agar plate. As a result, 186 isolates (54.4%) shown the antifungal activity against B. cinerea. The culture filtrates of selected fungi completely suppressed the growth of the microorganisms, indicating that suppression was due to the presence of antimicrobial substances in the culture filtrate. Mode of action of these fungi against insect involves the attachment of conidia to the insect cuticle, followed by germination, cuticle penetration, and internal dissemination throughout the insect. During infection process, secreted enzymes, proteinous toxins, and/or secondary metabolites secreted by entomopathogenic fungi can be used to overcome the host immune system, modify host behavior, and defend host resources. Recently, secondary metabolites isolated from entomopathogenic fungi have been reported as potential bioactive substances. Generally, most of bioactive substances produced by entomopathogenic fungi have reported low molecular weight (lower than 1,000 g/mol) as peptide and, in contrast the high molecular weight fungal bioactive substances are rare. Most substances based on entomopathogenic fungi were shown antimicrobial activity with narrow control ranges. In our study we analyzed the antimicrobial substances having antagonistic effects to B. cinerea. Antimicrobial substances in our fungal culture filtrates showed high thermostability, high stability to proteolytic enzymes, and hydrophilicity and their molecular weights were differed from substance. In conclusion, entomopathogenic fungi showed pathogenicity against insect pests and culture filtrate of the fungi also shown to antimicrobial activity. In the future, we can use the entomopathogenic fungi and its secondary metabolites to control both insect pest control and plant pathogenic fungi simultaneously.

• Korean Journal of Environmental Biology
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• v.35 no.2
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• pp.116-122
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• 2017

Basic dyes such as malachite green and methylene blue have been used as disinfectants to control water fungal infections since the 1930s. However, after succeeding reports of carcinogenicity and bioaccumulation of the dye, their use was forbidden in lieu of public health. This study undertook to evaluate the therapeutic effect of sulfur solution processed by effective microorganisms (EM-PSS) against Saprolegnia parasitica infection, and its safety in fish. In vitro antifungal evaluation of EM-PSS inhibited the growth of S. parasitica mycelia at concentrations of 50 ppm or higher. The acute toxicity test of EM-PSS to the mud fish (Misgurnus mizolepis) measured a no effect concentration (NOEC) at 100 ppm, the lowest effect concentration (LOEC) at 125 ppm, and the half-lethal concentration ($LC_{50}$) at 125 ppm in juvenile and 250 ppm in the immature stage. In addition, the ecotoxicity test of EM-PSS using Daphnia magna inhibited swimming of D. magna at concentrations of 100 ppm or less. Lastly, the EM-PSS prevented infection of S. parasitica to mud fish, at concentrations of 50 ppm. Furthermore, at 100 ppm concentration, the EM-PSS showed no acute toxicity on mud fish, nor any eco-toxic effects on D. magnano. Therefore, we conclude that carcinogenic disinfectants such as malachite green and methylene blue could be replaced by EM-PSS to remove S. parasitica in mud fish farming, and might be a potential eco-friendly disinfectant in aquaculture.

• Microbiology and Biotechnology Letters
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• v.44 no.2
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• pp.208-217
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• 2016

Pinus densiflora Sieb. et Zucc. (P. densiflora) contains several phenolic compounds that exhibit biological activities, such as antimicrobial, antioxidant, and antihypertensive effects. However, the anti-inflammatory effect of P. densiflora on skin has rarely been reported. Malassezia furfur (M. furfur) is a commensal microbe that induces skin inflammation and is associated with several chronic disorders, such as dandruff, seborrheic dermatitis, papillomatosis, and sepsis. The aim of our study was to identify the anti-inflammatory effects of P. densiflora needle extracts on skin health subjected to M. furfur-induced inflammation. The methanolic extract of the pine needles was partitioned into n-hexane, EtOAc, n-BuOH, and water layers. We measured the anti-inflammatory effects (in macrophages) as well as the antioxidant, antifungal, and tyrosinase inhibitory activity of each of these layers. The antioxidant activity of the individual layers was in the order EtOAc layer > n-BuOH layer > water layer. Only the n-BuOH, EtOAc, and n-hexane layers showed antifungal activity. Additionally, all the layers possessed tyrosinase inhibition activity similar to that of ascorbic acid, which is used as a commercial control. The EtOAc layer was not cytotoxic toward the RAW 264.7 cell line. Interleukin 1 beta and tumor necrosis factor (TNF)-α expression levels in M. furfur-stimulated RAW 264.7 cells treated with the EtOAc layer were decreased markedly compared to those in cells treated with the other layers. Taken together, we believe that the needle extracts of P. densiflora have potential application as alternative anti-inflammatory agents or cosmetic material for skin health improvement.

• Microbiology and Biotechnology Letters
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• v.49 no.1
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• pp.111-119
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• 2021

A bacterial strain isolated from a Malva verticillata leaf was identified as Bacillus velezensis MV2 based on the 16S rRNA sequencing results. Complete genome sequencing revealed that B. velezensis MV2 possessed a single 4,191,702-bp contig with 45.57% GC content. Generally, Bacillus spp. are known to produce diverse antimicrobial compounds including bacteriocins, polyketides, and non-ribosomal peptides. Antimicrobial compounds in the B. velezensis MV2 were extracted from culture supernatants using hydrophobic interaction chromatography. The crude extracts showed antimicrobial activity against both gram-positive bacteria and gram-negative bacteria; however, they were more effective against gram-positive bacteria. The extracts also showed antifungal activity against phytopathogenic fungi such as Fusarium fujikuroi and F. graminearum. In time-kill assays, these antimicrobial compounds showed bactericidal activity against Bacillus cereus, used as indicator strain. To predict the type of antimicrobial compounds produced by this strain, we used the antiSMASH algorithm. Forty-seven secondary metabolites were predicted to be synthesized in MV2, and among them, fourteen were identified with a similarity of 80% or more with those previously identified. Based on the antimicrobial properties, the antimicrobial compounds may be nonribosomal peptides or polyketides. These compounds possess the potential to be used as biopesticides in the food and agricultural industry as an alternative to antibiotics.

• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.28-35
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• 1998

An antimicrobial peptide producing bacterium, Bacillus subtilis A405, was screened and identified among 700 of antagonistic bacteria. The heat-resistant antimicrobial peptide, AMP-405, was purified from the broth culture of B. subtilis A405 through $20{\sim}40%$ ammonium sulfate precipitation and ultrafiltration. The AMP-405 exhibited strong antimicrobial activities against Botrytis cinerea, Cercospora sp., Fusarium oxysporum, Penicillium digitatum, Celletotrichum gloeosporioides, Rhizoctonia solani, Pythium ultimum, Pyricularia oryzae, Escherichia coli, Pseudomonas spp. and Candida albicans. The molecular weight of the peptide was about 3.0 kDa determined by SDS-PAGE, Native-PAGE and Tris-Tricine gradient electrophoresis, and composed of 9 kinds of amino acid such as aspartic acid, glycine, serine, glutamine, valine, leucine, isoleucine, proline, tyrocine. To determine the efficiency of AMP-405 as a potential maintenance of fruits freshness, cherry tomato was srored at $25^{\circ}C$ for 2 weeks after treatment with $50{\mu}g/ml$ of AMP-405 and $10^{5}$ spores/ml of Botrytis cinerea simultaneously. Treatment with AMP-405 resulted in significantly less infection by Botrytis cinerea, than the treatment with tap water as a control.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.1
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• pp.1-11
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• 2009

Essential oils are mixture of volatile, lipophilic compounds originating from plants. Essential oils have potential biological effects, i.e., antibacterial, antifungal, spasmolytic and antiplasmodial activities and insect-repellent property. In this study, five essential oils, namely R, LG, FR, O, and NM, extracted from various aromatic plants were used to test their antimicrobial activity against the oral microorganisms. The effects of essential oils were investigated against eight important bacteria, Streptococcus mutans (S. mutans), Staphylococcus aureus (S. aureus), Streptococcus sanguis (S. sanguis), Streptococcus anginosus (S. anginosus), Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans), Streptococcus sobrinus (S. sobrinus), Staphylococcus epidermidis (S. epidermidis), and Escherichia coli (E. coli). Essential oils, except NM, effectively inhibited the growth of tested oral pathogenic microorganisms dose-dependently. However, the essential oils didn't show a significant inhibitory effect against E. coli and S. epidermidis. Consequently, these results represented that essential oil-mediated anti-microbial activity was prominent against the oral pathogenic bacteria. For example, minimum bactericidal concentration(MBC) of R, LG, FR oil against A. actinomycetemcomitans was very low as 0.078 mg/mL. In addition, minimum inhibitory concentration (MIC) of R, LG, FR, O oil against S. mutans was low as 0.156 mg/mL in vitro.

• Research in Plant Disease
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• v.22 no.2
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• pp.81-93
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• 2016

Out of plant-associated bacteria, certain plant growth-promoting bacteria (PGPB) have been reported to increase plant growth and productivity and to elicit induced resistance against plant pathogens. In this study, our objective was to broaden the range of applications of leaf-colonizing PGPB for foliar parts of road tress and pepper. Total 1,056 isolates of endospore-forming bacteria from tree phylloplanes were collected and evaluated for the enzymatic activities including protease, lipase, and chitinase and antifungal capacities against two fungal pathogens, Colletotrichum graminicola and Botrytis cinerea. Fourteen isolates classified as members of the bacilli group displayed the capacity to colonize pepper leaves after spraying inoculation. Three strains, 5B6, 8D4, and 8G12, and the mixtures were employed to evaluate growth promotion, yield increase and defence responses under field condition. Additionally, foliar application of bacterial preparation was applied to the road tress in Yuseong, Daejeon, South Korea, resulted in increase of chlorophyll contents and leaf thickness, compared with non-treated control. The foliar application of microbial preparation reduced brown shot-hole disease of Prunus serrulata L. and advanced leaf abscission in Ginkgo biloba L. Collectively, our results suggest that leaf-colonizing bacteria provide potential microbial agents to increase the performance of woody plants such as tree and pepper through spray application.

• The Korean Journal of Pesticide Science
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• v.8 no.2
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• pp.137-144
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• 2004

[ $\beta$ ]-Ketoacetoanilide chloride derivatives containing a substituent at 4 in phenyl group (para) reduced specifically the development of tomato late blight caused by Phytophthora infestans. Among $\beta$ketoacetoanilide chloride derivatives, five (KIST163, KIST170, KIST260, KIST263, and KIST267) were selected and tested for their protective, curative, systemic, persistent activities, and disease control efficacy against tomato late blight on adult plants. They exhibited a strong l-day protective activity and $EC_{50}$ of KIST163 and KIST170 were 21.9 and $14.5{\mu}g/mL$, respectively. However, they had little curative and systemic activities. Good persistence of KIST163 and KIST170 on tomato plants were observed against P. infestans; both KIST163 and KIST170 at $100{\mu}g/mL$ showed control values more than 75% in a 7-day protective applications. In addition, the two chemicals effectively controlled the occurrence of P. infestans on adult tomato plants. These results indicate that five $\beta$-ketoacetoanilide chloride derivatives are foliar fungicides with a preventive action and KIST163 and KIST170 have a potential for the control of tomato late blight in the fields.

• The Korean Journal of Pesticide Science
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• v.13 no.4
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• pp.275-282
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• 2009

The effect of two plant growth-promoting rhizobacteria (PGPR) on plant growth and systemic protection against soft rot disease and stem rot disease of canola (Brassica napus), caused by Erwinia carotovora and Sclerotinia sclerotiorum was investigated in a laboratory and a greenhouse. Selected PGPR strains C4 and D8 were treated to canola seeds by soaking. Strains C4 and D8 significantly not only increased plant height and root length about 74% and 40.3% and also reduced disease severity of soft rot disease by 80% by C4 and D8 respectively, compared to the control. Especially strain C4 showed antifungal activity against 6 fungal pathogens, S. sclerotiorum, Rhizoctonia solani, Botrytis cinerea, Fusarium oxysporum, Phytophthora capsici and Colletotrichum acutatum. In greenhouse experiment, the seed treatment of both of them increased plant height, leaf width and leaf length of canola plant to 19.5% and 24.9%, 11.3% and 15.3%, and 14.1% and 20.7% by C4 and D8, respectively, and reduced disease severity of S. sclerotiorium. These results indicate that these two PGPR strains can decrease disease severity and increased plant growth under greenhouse condition. Therefore, these two bacteria have a potential in controlling Sclerotinia stem rot of canola. These strains have to investigate under field condition to determine their role of antibiosis, induced systemic resistance and plant growth promotion on canola.