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

• Research in Plant Disease
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• v.16 no.2
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• pp.170-175
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• 2010

A monoterpenoid benzylideneacetone (BZA) is a bacterial metabolite isolated from culture broth of an entomopathogenic bacterium, Xenorhabdus nematophila K1. It was tested in this study the control efficacy of the metabolite against two major fungal diseases occurring in red-pepper plants. BZA exhibited significant antifungal activities against Phytophthora capsici and Colletotrichum acutatum. Under natural light conditions, the antifungal activity of BZA was maintained for more than sixty days. The antifungal activity of BZA was not lost even in soil because the incidence of Phytophthora blight against red-pepper plants was significantly reduced when the suspensions of P. capsici were poured to the rhizosphere soils mixed with BZA. Application of the BZA suspension spray to the fruit surface infected with C. acutatum significantly suppressed the disease occurrence of anthracnose on the red-pepper plants. These results suggest that BZA can be used to develop a promising agrochemical to control phytophthora blight and anthracnose of redpepper plants.

• The Plant Pathology Journal
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• v.29 no.2
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• pp.125-135
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• 2013

In agro-ecosystems worldwide, some of the most important and devastating diseases are caused by soil-borne necrotrophic fungal pathogens, against which crop plants generally lack genetic resistance. However, plants have evolved approaches to protect themselves against pathogens by stimulating and supporting specific groups of beneficial microorganisms that have the ability to protect either by direct inhibition of the pathogen or by inducing resistance mechanisms in the plant. One of the best examples of protection of plant roots by antagonistic microbes occurs in soils that are suppressive to take-all disease of wheat. Take-all, caused by Gaeumannomyces graminis var. tritici, is the most economically important root disease of wheat worldwide. Take-all decline (TAD) is the spontaneous decline in incidence and severity of disease after a severe outbreak of take-all during continuous wheat or barley monoculture. TAD occurs worldwide, and in the United States and The Netherlands it results from a build-up of populations of 2,4-diacetylphloroglucinol (2,4-DAPG)-producing fluorescent Pseudomonas spp. during wheat monoculture. The antibiotic 2,4-DAPG has a broad spectrum of activity and is especially active against the take-all pathogen. Based on genotype analysis by repetitive sequence-based-PCR analysis and restriction fragment length polymorphism of phlD, a key 2,4-DAPG biosynthesis gene, at least 22 genotypes of 2,4-DAPG producing fluorescent Pseudomonas spp. have been described worldwide. In this review, we provide an overview of G. graminis var. tritici, the take-all disease, Pseudomonas biocontrol agents, and mechanism of disease suppression.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.3
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• pp.303-307
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• 2008

Cotyledon Black Decay (CBD) on soybean sprout mimics the black spot due to microbial infection. CBD, not visible or predictable at seedlot state, for some reason, shows up exclusively on cotyledon of soybean sprout during sprouting process. Such an incidence rate fluctuated from 0.8 to 19.5% over three years from 2004. We suspected some pod-infecting anthracnose fungi and/or pod-blight pathogen, or pod-sucking bean bug, one of the major pests of soybean, might have involved, of which we ruled out fungal pathogen because it was preventable through heat treatment, a proven method for seedlot disinfestation. The healthy seeds artificially fed by bean bug for one to seven days were sprouted, and 6 to 41% of the soybean sprout revealed the CBD mimic to those occurred in soybean sprout from previous commercial seedlot screening experiments. This finding is the first report to confirm that bean bug damage to pod at $R_8$ stage is directly responsible for the CBD, which did not concur with any other deleterious effects on sprouting such as reduction in hypocotyls elongation and rooting except unsightly sprout quality. However, earlier feeding either at green pod or greenish yellow pod stage ($R_6$ -early $R_7$ stage) resulted in rather severe damages, which strikingly reduced hypocotyls growth to about one forth to about two third, as well as the reduction in rates of seed germination.

• The Korean Journal of Mycology
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• v.44 no.3
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• pp.193-195
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• 2016

Korean ginseng (Panax ginseng) possesses various biological and pharmacological properties. Damping-off is a critical disease on ginseng seedlings, which is caused by the fungal pathogens Rhizoctonia solani and Pythium sp.. This disease is generally controlled by the application of fungicides, but also biological control is an efficient and environmentally friendly way to prevent ginseng damping-off. In a previous study, we screened soil-borne bacteria with potential applications as biological control agents for ginseng damping-off and selected the bacterial strain Streptomyces sp. A3265, producing antifungal substances guanidylfungin and methylguanidylfungin. In this study, we investigated control efficacy of Streptomyces sp. A3265 against ginseng damping-off in the field. As a result, the incidence of damping-off was significantly reduced when soaking ginseng seeds in the culture broth of Streptomyces sp. A3265.

• Journal of Oral Medicine and Pain
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• v.46 no.2
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• pp.33-40
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• 2021

Purpose: Oral candidiasis is the most common fungal infection in the oral cavity which is usually diagnosed from clinical findings. A retrospective study was conducted to identify risk factors for oral candidiasis and to characterize the demographic and clinical features of affected patients. Methods: From January 1, 2019 to December 31, 2019, it consisted of 90 oral candidiasis patients diagnosed based on clinical finding and treated with antifungal drugs. As a retrospective study of those people, surveys were conducted on sex, age, systemic disease, a use of dentures, complaints of dry mouth, smoking and alcohol consumption, culture on potato dextrose agar (PDA) medium, culture on chromogenic agar (CA) medium and a duration of antifungal treatment. Results: Among 90 selected patients, the male and female ratio was 41:49. Overall, female had a higher infection rate than male in all age groups. In this study, oral candidiasis was not clearly susceptible to dry mouth, smoking or drinking, wearing dentures and association with systemic disease. Among 90 patients with oral candidiasis, 83 had colonies formed on PDA medium and 53 had colonies formed on CA medium. The duration of antifungal treatment was highest between 5 and 8 weeks. In addition, there was statistical significance between the culture results in CA medium and the duration of antifungal treatment. Conclusions: Generally, old age or infants, dry mouth, smoking, a use of dentures and endocrine abnormalities are risk factors to increase oral candidiasis; however, in this study, it was mainly found in the elderly aged 60 or older regardless of sex and the incidence of oral candidiasis was not obviously related with patients with dry mouth, smoking or drinking, denture wearers and endocrine abnormalities. Interestingly, when the fungi were cultured in CA medium, the duration of antifungal treatment was increased.

• Microbiology and Biotechnology Letters
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• v.50 no.2
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• pp.202-210
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• 2022

Aflatoxin contamination in rice has been documented in a number of studies, and has a high incidence in Asian countries, and as such, there has been a growing interest in alternative biocontrol strategies to address this issue. In this study, 147 strains of yeasts and yeast-like fungi were screened for their potential to produce volatile organic compounds (VOCs) active against Aspergillus flavus strains that produce aflatoxin B₁ (AFB₁). Five strains within four different genera showed greater than 50% growth inhibition of some strains of A. flavus. These were Anthracocystis sp. DMKU-PAL124, Aureobasidium sp. DMKU-PAL120, Aureobasidium sp. DMKU-PAL144, Rhodotorula sp. DMKU-PAL99, and Solicococcus keelungensis DMKU-PAL84. VOCs produced by these microorganisms ranged from 4 to 14 compounds and included alcohols, alkenes, aromatics, esters and furans. The major VOCs produced by the closely related Aureobasidium strains were found to bedistinct. Moreover, 2-phenylethanol was the most abundant compound generated by Aureobasidium sp. DMKU-PAL120, while methyl benzeneacetate was the major compound emitted from Aureobasidium sp. DMKU-PAL144. On the other hand, 2-methyl-1-butanol and 3-methyl-1-butanol were significant compounds produced by the other three genera. These antagonists apparently inhibited A. flavus sporulation and mycelial development. Additionally, the reduction of the AFB1 in the fungal-contaminated rice grains was observed after co-incubation with these VOC-producing strains and ranged from 37.7 ± 8.3% to 60.3 ± 3.4%. Our findings suggest that these same microorganisms are promising biological control agents for use against aflatoxin-producing fungi in rice and other agricultural products.

• Journal of Animal Science and Technology
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• v.64 no.2
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• pp.343-352
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• 2022

Pig slaughterhouses harbor high humidity because of the necessary cleaning that takes place simultaneously with slaughter, which facilitates the existence of mold. Due to the enclosed space, there are several limitations to the control of mold growth with respect to cleaning, ventilation, and drying. In this study, the prevalence of fungi was investigated in four pig slaughterhouses in Korea. Four fungi (Aspergillus niger, Penicillium commune, Penicillium oxalicum, and Cladosporium cladosporioides) were detected with the highest frequency. These four strains were subjected to various treatments to reduce their growth. The fungi were inoculated onto stainless steel (SS) chips and treated with ultraviolet (UV)-C irradiation and hot water. Individual treatments with UV-C (15, 30, 90, 150, 300, and 600 mJ/cm²), and hot water (60, 65, 70, and 83℃) were performed to sanitize the SS chips. Simultaneous cleaning with 60℃ hot water and more than 150 mJ/cm² of UV-C reduced the fungal incidence by > 6.5 Log from 6.6-7.0 Log CFU/cm² (initial count). Our results demonstrate that a combined treatment of UV-C and hot water is the most economical and convenient way to prevent microbiological contamination of small tools (such as knives and sharpeners) and steel surfaces in slaughterhouses.

• Korean journal of applied entomology
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• v.25 no.2 s.67
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• pp.107-112
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• 1986

Species of pathogens and insects associated with grain discoloration in the Philippines were indentified. Leptocorisa oratorios was the most dominant insect species causing discoloration. Pathogenicity tests of fungal organisms isolated from discolored grains showed that Drechslera oryzae, Curvularia lunata, Trichoconiella padwickii, Sarocladium oryzae, Alternaria tenuis, and Fusarium solani were the common pathogens responsible for 'dirty panicle' disease of rice. Discoloration incidence was higher on treatment when both pests were present than when they occurred singly. The discoloration severity was attributed to the pathogens whereas rice bug caused a high decrease in grain weight and unfilled grains. Rice bug feeding on grains enhances the infection caused by the pathogen. Due to this, the quantity and quality of grains produced were affected, resulting in yield reduction.

• Journal of Bio-Environment Control
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• v.26 no.2
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• pp.140-145
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• 2017

This study was conducted to find out the effects of $CO_2$ fertilization (1,000ppm) on the quality and storability of 'Maehyang' strawberry fruits. Qualities such as firmness, soluble solid, and acidity of strawberry fruits showed higher numbers in those treated with $CO_2$ fertilization compared to those after harvest. Strawberry fruits were stored at $8^{\circ}C$; MA condition using $20,000cc{\cdot}m^{-2}{\cdot}day^{-1}{\cdot}atm^{-1}$ OTR (oxygen transmission rate) films and conventional condition using unsealed PE box stored for 20 and 10 days, respectively. Fresh weight loss rate was less than 1.0% in MA storage regardless of $CO_2$ fertilization treatment. Concentrations of oxygen, carbon dioxide, and ethylene in OTR films did not show any significant difference between $CO_2$ fertilization treatment and control (nontreatment) during storage. $CO_2$ fertilization treatments maintained higher firmness after storage regardless of storage methods, but soluble solid, acidity, and surface color did not differ among the treatments. Visual quality and off-flavor based on sensory evaluation was the highest in $CO_2$ fertilization treated strawberry and stored at a MA condition, and was the lowest in $CO_2$ fertilization treated strawberry and those stored in a conventional condition, respectively. The fungal incidence rate of strawberry fruits showed less in $CO_2$ fertilization treatment than control during both MA and conventional storage. These results suggest that $CO_2$ fertilization can improve firmness, increase visual quality after harvest and storage at $8^{\circ}C$, and the MA storage method enhances the shelf-life of 'Maehyang' strawberry fruits.