• Journal of Life Science
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• v.27 no.6
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• pp.688-693
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• 2017

Antifungal bacterium against Colletotrichum coccodes causing black dot disease of potatoes and anthracnose of tomatoes was isolated from sewage sludge. The isolate showed a 99% sequence homology of partial 16S rRNA of Bacillus methylotrophicus CBMB205 and Bacillus amyloliquefaciens subsp. plantarum FZB42. The isolate was identified as Bacillus sp. SW29-2, using the neighbor-joining phylogenetic tree, BlastN sequence analysis, and morphological and cultural characteristics. Bacillus sp. SW29-2 is an aerobic, Gram-positive, endospore-forming bacterium, of which the morphological and physiological characteristics were the same as those of type strain B. lichniformis CBMB205, except for the cell growth of over 4% NaCl. The cell growth of the temperature and the initial pH of the medium was shown at $18-47^{\circ}C$ (opt. ca. $38^{\circ}C$) and 3-9 (opt. ca. 6.0), respectively. The inhibition size (diameter) of Bacillus sp. SW29-2 against four strains of C. coccodes ranged from 23 to 29 mm. Also, the isolate showed antifungal activity against penicillium rot-causing Penicillium expansum in apples. Thus far, any report on the antifungal activity of Baciilus spp. against C. coccodes has not been found. These results suggest that the Bacillus sp. SW29-2 isolate could be used as a possible biocontrol agent against C. coccodes, and further applied to other plant pathogenic fungi.

• Korean Journal of Heritage: History & Science
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• v.37
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• pp.327-348
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• 2004

In this study, after analyzing several local climate characteristics of South Korea, I validated distribution, invasion, foraging, underground activities, attack season as ecological characteristics and also temperature, relative humidity, and tree species as preference characteristics of Korean termites (Reticulitermes speratus kyushuensis Morimoto). Especially, southern part of the Korean peninsula is a suitable area for inhabitation and motion of termites holding same ecological characteristic like R. speratus kyushuensis. Busan is a neighboring district at field distribution north limiting temperature of Coptotermes formosanus Shiraki and Chuncheon is a passing area through the Korean Peninsula of field distribution north limiting temperature of Reticulitermes speratus Kolbe. The termite attack of wood devices was about 34.5% for 3 years in the forest of Jongmyo. Although the attack rate of termite increased each year, the detection rate decreased and the missing rate was high by degrees. I confirmed a foraging habits which is a part of termite colony was a role of continuous decomposition and another was a role of new food hunt as experimental results. The foraging termites were found under ground at Jongmyo in Seoul from April to November in the 2001 and the most active period was on July and August. The termite invasion rate of bait station increased in every monitoring. Through the increasing attack rate of bait station during 2nd monitoring (November, 2000) and 3rd monitoring(March, 2001), I confirmed that termites moved into the deep underground in winter, and were working continuously to forage. R. speratus kyushuensis inhabiting at the Korean Peninsula is a species which has food consumption rate with higher temperature. The termite revealed the greatest amount of food(filter paper) at $30^{\circ}C$(90% RH), but showed increasing death rate at over $32^{\circ}C$. Also, survival rate of this termite was 97% at 84% RH($30^{\circ}C$), but killed 100% at 52% RH($30^{\circ}C$) and 70% RH($30^{\circ}C$). For wood feeding, this was observed the preference in a pine tree(Pinus densiflora) above all others. Survival of termites was high(87%) at a pine tree, but low(13.5%) at a paulownia tree(Paulownia coreana). In this study, I presented the biological characteristic of termite(R. speratus kyushuensis Morimoto) and confirmed the deterioration degree of termite on wooden cultural heritage in Korea. Depending on climate and soil temperature, each area in the southern part of the Korea Peninsula, has some different active period and different distribution of R. speratus kyushensis. With these results, I expect that this report helps to prepare the integrated pest management(IPM) of the termite on wooden cultural heritage in Korea, and it may help to reduce the economical loss from termite damage in Korea.

• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.603-613
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• 2019

This study was carried out to examine the antagonistic effect against phytopathogenic fungi of isolated strains from soil samples collected from Busan, Changwon, and Jeju Island: Botrytis cinerea, Colletotrichum acutatum, Corynespora cassiicola, Fusarium sp., Rhizoctonia solani, Phytophthora capsici, and Sclerotinia sclerotiorum. According to results of our studies, isolated strains showed an antagonistic effect against phytopathogenic fungi. Such an antagonistic effect against phytopathogenic fungi is seen due to the production of siderophores, antibiotic substances, and extracellular amylase, cellulase, protease, and xylanase enzyme activities. Extracellular enzymes produced by isolated strains were significant, given that they inhibited the growth of phytopathogenic fungi by causing bacteriolysis of the cell wall of plant pathogenic fungi. This is essential to break down the cell wall of plant pathogenic fungi and thus help plant growth by converting macromolecules, which cannot be used by the plant for growth, into small molecules. In addition, they are putative candidates as biological agents to promote plant growth and inhibit growth of phytopathogenic fungi through nitrogen fixation, indole-3-acetic acid production, siderophore production, and extracellular enzyme activity. Therefore, this study suggests the possibility of using Bacillus subtilis ANGa5, Bacillus aerius ANGa25, and Bacillus methylotrophicus ANGa27 as new biological agents, and it is considered that further studies are necessary to prove their effect as novel biological agents by standardization of formulation and optimization of selected effective microorganisms, determination of their preservation period, and crop cultivation tests.

• Journal of Life Science
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• v.31 no.7
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• pp.641-653
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• 2021

The purpose of this study was to confirm the antifungal activity, plant growth-promoting activity, and mineral solubilizing activity of 18 types of bacteria isolated purely from rhizosphere soil. The potential of isolates of the genus Bacillus and Pseudomonas as biocontrol agents was confirmed through the antifungal activity of these isolates. This activity has been determined to be due to various hydrolytic enzymes on the cell wall of plant pathogenic fungi and the production of siderophores in isolates. In addition, most of the isolates have been found to have aminocyclopropane-1-carboxylate deaminase production activity, indole-3-acetic acid production activity, and nitrogen fixation activity. These characteristics are believed to have a positive effect on root development, growth, and the productivity of crops via a reduction in the concentration of ethylene under conditions of environmental stress, to which plants are commonly exposed. In addition, on testing for the solubilizing activity of the isolates for phosphoric acid, silicon, calcium carbonate, and zinc, some isolates were found to have mineral solubilizing activities. Inoculation of these isolates during plant growth is expected to assist plant growth by converting nutrients necessary for growth into usable forms that can be absorbed by plants. The 18 isolated strains can be used as biocontrol agents due to their antifungal activity, plant growthpromoting activity, and mineral solubilizing activity.

• Horticultural Science & Technology
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• v.31 no.3
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• pp.366-370
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• 2013

This experiment was carried out to establish the screening methods for the selection of Zantedeschia aethiopica cultivars resistant to calla lily soft rot caused by Pectobacterium carotovorum subsp. carotovorum. A center of leaf and petiole tissues of four Z. aethiopica cultivars were wounded and inoculated with three different inoculum concentrations, $1{\times}10^7cfu/mL$, $1{\times}10^8cfu/mL$, and $1{\times}10^9cfu/mL$, of EccNHRI-21 isolate. And they were evaluated at 4, 18, and 26 hours after inoculation. The lesion of maceration was developed well in the leaf tissues inoculated with $1{\times}10^9cfu/mL$ concentration. And evaluation of resistance in 18 hours after inoculation was correlated with field resistance positively. Using this method, ten Z. aethiopica commercial cultivars and four wild types were screened. 'Crowbrough' and 'White Cutie' were selected as highly resistant genotypes and 'Mont Blanc' and 'Silky White' as resistant genotypes. 'Wedding March' and 'Kiwi Blush' were evaluated as moderate resistant and the others including 'Childsiana' were susceptible. And all of four wild types were evaluated as more than moderate resistant. In spite of control through cultural, biological and chemical methods, the use of resistant cultivars is most efficient to overcome calla lily soft rot. This newly developed screening method was helpful for breeding new varieties resistant to calla lily soft rot.

• Korean Journal of Environmental Biology
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• v.41 no.3
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• pp.273-282
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• 2023

Hypochaeris radicata, native to Europe and Eurasia, is a perennial plant of the Asteraceae family. In Korea, H. radicata was reported in 1992, mainly in Jeju Island, and gradually spreading to the inland. It overwinters in the form of a rosette and blooms yellow flowers from May to June. H. radicata propagates by seeds and rhizomes. The germination temperature of the seed is 15/20℃ (day/night), and the rhizome forms a new plant at a depth of 2-3cm in the soil. The roots of H. radicata secrete allelochemicals that inhibit the development of other plants. Some use it as a salad or forage substitute but to a limited extent. However, extensive research on ampicillin contained in H. radicata has been conducted, and its anticancer and anti-inflammatory effects have been recognized. There are only a few methods to manage H. radicata both culturally and physically. In orchards, soil treatments such as oxyfluorfen and diclobenil, or nonselective foliar treatments such as glufosinate-ammonium and glyphosate are used. Notably, there are no known biological control agents.

• Journal of Mushroom
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• v.11 no.4
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• pp.230-239
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• 2013

The major species of fungus gnats which caused the severe damage in shiitake farm were identified as a Bradysia difformis, B. alpicola, and Camtomyia cortocalis on oak log beds cultivation. The B. difformis occurred early in the middle of March while B. alpicola and C. cortocalis appeared since the beginning of May. The occurrence rate for adults of B. difformis showed highly at the end of July (11.9~1,774.2 in dong-myeon and 0.4~2,583.3 in pungse-myeon) in 2012 and mid-June (10.7~4,650 in dong-myeon and 36.8~4740 in pungse-myeon) in 2013. The counting numbers on the traps for B. alpicola reached highest peak in the middle of June (2.1~63.2 in dong-myeon and 1.0~21.7 in pungse-myeon) and the end of May (0.8~163.7 in dong-myeon and 0.5~280.5 in pungse-myeon) in 2012 and 2013, respectively. The number of C. cortocalis showed high record in the middle of May in 2012 (0.6~4.7) and in the middle of June (2.1~17.3) in 2013 in dong-myeon whereas showed the peaks in the middle of May (0.6~4.7) in 2012 and in the late of May (1.3~17.6) in 2013 in pungse-myeon. The fruiting bodies of shiitake mushroom by fungus gnats were severely damaged from mid-June to late-July and the damage rate were 0.625.5% (2012) and 0.7~30.5% (2013) in dong-myeon and 1.5%~21.6% (2012) and 1.9~36.8%(2012) in pungse-myeon. To investigate the control effect for fungus gnats by Hypoaspis aculeifer, H. aculeifer (30 mixutre of nymph and adult per $m^2$) were treated to oak log beds shiitake cultivation for six times (May 2 and 28, June 25, July 10 and 25 and August 28). The occurrence rate of adults and damage rate of fruiting bodies of 3 major species reduced 79.3% (adult numbers) and 74.8% (fruiting bodies) in dong-myeon and 64.1% (adult numbers) and 65.5% (fruiting bodies) in pungse-myeon, respectively, compared to non-treatment. Accordingly, H. aculeifer effectively controlled the fungus gnats on shiitake mushroom and can be used as good control agent.

• Weed & Turfgrass Science
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• v.2 no.1
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• pp.70-75
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• 2013

Seven medicinal plant extracts were tested for antifungal activities against six species of the major turfgrass pathogenic fungi (Colletotrichum graminicola, Pythium spp., Rhizoctonia cerealis, Rhizoctonia solani AG1-1, Rhizoctonia solani AG2-2, and Sclerotinia homoeocarpa) using paper disk diffusion method. Three medicinal plant extracts, including Pinus densiflora showed antifungal activities. In suppression of mycelium growth test, on medium adding P. densiflora extract showed that inhibition rate of mycelium growth were above 80% in 10 mg/10 ml concentration of the extract. The inhibition rate of Pythium spp. was 100% and C. graminicola was 84.3% in 10 mg/10 ml concentrations of P. densiflora extract, respectively. In particularly, the inhibition rate of Pythium spp. was 89.5% in 2 mg/10 ml concentrations of P. densiflora extract. As a result, P. densiflora extract showed high antifungal activity to Pythium spp. and C. graminicola of the turfgrass pathogen in in vitro test.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.398-402
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• 2013

This study was to investigate beneficial effects of microbial mixture on red pepper which was capable of promoting plant growth by solubilizing insoluble phosphate as well as protecting plants from pathogenic attack. Saccharomyces sp. L13 was isolated for phosphate solubilizing activity on aluminium phosphate, tricalcium phosphate, calcium hydrophosphate, and magnesium hydrophosphate. On the other hand, Bacillus sp. L32 was isolated for antagonistic activity against Phytophthora capsisi and Colletotrichum gloeosporioides, causing Phytophthora blight and Anthracnose disease in pepper, respectively. The strain L32 exhibited antagonistic activities both under dual culture assays and detached leaves assays. The each strain under the condition of mixed cultivation exhibited the same growth rates as one under pure cultivation. In greenhouse study, the mixed culture showed the both effect of plant growth promotion and reduction of disease symptom development against P. capsisi and C. gloeosporioides providing a potential as effective microbial agent for plant husbandry.

• Research in Plant Disease
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• v.20 no.4
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• pp.264-269
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• 2014

The effect of biological control of the root-knot nematode, Meloidogyne incognita, on cucumber and lettuce was evaluated with green manure crop species in greenhouse. Nematicidal effect of sudan grass cultivation in cucumber greenhouse was comparable to that of chemical treatment with fosthiazate GR, showing the high activity of 88.6%. Sudan grass cultivation in lettuce greenhouse significantly reduced the number of M. incognita in soil, showing 93.5% of nematiidal activity. In addition, since growth of sudan grass was superior to other green manure crop species, it is considered that cultivation of sudan grass is proper to control M. incognita in greenhouse.