• The Korean Journal of Mycology
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• v.42 no.4
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• pp.262-268
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• 2014

A fungal isolate DUCC5000 from a garden plant Pachysandra terminalis was identified as Paraconiothyrium brasiliense based on the results of morphological and molecular studies. The fungus formed brown to black conidiomata of (0.2-0.7)-2(-3.5) mm singly or as a group on PDA. Conidia measured $2-5{\times}1.8-3{\mu}m$ in size, hyaline, ellipsoid to short-cylindrical, and rounded at both ends. The internal transcribed spacer (ITS) DNA of the isolate shared 100% nucleotide sequence homology with those of known P. brasiliense isolates. Phylogenetic tree inferred from the ITS sequence analysis showed that the DUCC5000 isolate formed a clade with known isolates of P. brasiliense. The fungal mycelia grew better on oatmeal agar than on MEA and PDA. On PDA media under various pH conditions, fungal mycelial growth was observed at pH 9. Colony morphology of the fungus tended to alter depending on the kinds of nutrient media and pH condition. On chromagenic media, the fungus demonstrated its ability to produce extracellular enzymes including amyalse, avicelase, ${\beta}$-glucosidase, protease, and xylanase. However, in pathogenicity testing, no disease symptoms were observed on the leaves of P. terminalis. This strain is the first report on P. terminalis in Korea.

• Korean Journal of Microbiology
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• v.53 no.3
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• pp.193-199
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• 2017

This study was aimed to evaluate the antimicrobial activity of Penicillium purpurogenum ED76 on several clinically important microorganisms. The endophytic fungus P. purpurogenum ED76 was previously isolated from Swietenia macrophylla leaf. The antimicrobial efficacy of P. purpurogenum ED76 dichloromethane extract was determined via disc diffusion and broth microdilution assay. A kill curve study was conducted and the morphology of extract treated bacterial cells were viewed under scanning electron microscope. The dichloromethane extract showed significant inhibitory activity on 4 test bacteria and 2 test yeasts. The minimal inhibitory concentration of the extract ranged from 125 to $1,000{\mu}g/ml$, which indicates the different susceptibility levels of the test microorganisms to the fungal extract. The kill curve study has revealed a concentration-dependent inhibition for all test microorganisms. With the increase of the extract concentration, the microbial growth was significantly reduced. The scanning electron micrograph of dichloromethane extract-treated Staphylococcus aureus cells showed the total damage of the cells. The cell wall invagination of the bacterial cells also indicates the loss of cellular materials and metabolic activity. The gas chromatography mass spectrometry analysis of the extract also showed that the major compound was stigmasterol, which constitutes 45.30% of the total area. The dichloromethane extract of P. purpurogenum ED76 exhibited significant inhibitory activity on several clinically important bacteria and yeasts. The study proposed a possible mode of action that the extract cause significant damage to the morphology of S. aureus cells.

• Journal of Microbiology and Biotechnology
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• v.29 no.10
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• pp.1570-1579
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• 2019

The fungal products dibenzodioxocinones promise a novel class of inhibitors against cholesterol ester transfer protein (CEPT). Knowledge as to their biosynthesis is scarce. In this report, we characterized four more dibenzodioxocinones, which along with a previously described member pestalotiollide B, delimit the dominant spectrum of secondary metabolites in P. microspora. Through mRNA-seq profiling in $g{\alpha}1{\Delta}$, a process that halts the production of the dibenzodioxocinones, a gene cluster harboring 21 genes including a polyketide synthase, designated as pks8, was defined. Disruption of genes in the cluster led to loss of the compounds, concluding the anticipated role in the biosynthesis of the chemicals. The biosynthetic route to dibenzodioxocinones was temporarily speculated. This study reveals the genetic basis underlying the biosynthesis of dibenzodioxocinone in fungi, and may facilitate the practice for yield improvement in the drug development arena.

• Journal of agriculture & life science
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• v.50 no.1
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• pp.1-22
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• 2016

In this study, the securing state of nationally indicated beneficial microbial resources was evaluated in an aspect of bio-diversity using their taxonomical information. Depending on the analysis result with the Margalef's richness or the Mehinick's index which are representative bio-diversity analytical indices, species diversity values was revealed as 8.537, 3.546 within bacterial resources, 3.349, 2.167 within fungal resources. Several developed or researched beneficial strains and spoilage microbes showed relative taxonomical relationship with comparation of their biological information. As a result, we propose the necessity or countermeasure method for preventing the microbial spoilage with the overhauling consideration of advanced research on agricultural microbiology covering crop endophyte beneficial/spoilage microorganisms.

• Journal of Microbiology and Biotechnology
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• v.24 no.9
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• pp.1149-1161
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• 2014

Cotton plants were sampled and ranked according to their resistance to Verticillium wilt. In total, 642 endophytic fungi isolates representing 27 genera were recovered from Gossypium hirsutum root, stem, and leaf tissues, but were not uniformly distributed. More endophytic fungi appeared in the leaf (391) compared with the root (140) and stem (111) sections. However, no significant difference in the abundance of isolated endophytes was found among resistant cotton varieties. Alternaria exhibited the highest colonization frequency (7.9%), followed by Acremonium (6.6%) and Penicillium (4.8%). Unlike tolerant varieties, resistant and susceptible ones had similar endophytic fungal population compositions. In three Verticillium-wilt-resistant cotton varieties, fungal endophytes from the genus Alternaria were most frequently isolated, followed by Gibberella and Penicillium. The maximum concentration of dominant endophytic fungi was observed in leaf tissues (0.1797). The evenness of stem tissue endophytic communities (0.702) was comparatively more uniform than the other two tissues. Eighty endophytic fungi selected from 27 genera were evaluated for their inhibition activity against highly virulent Verticillium dahliae isolate Vd080 in vitro. Thirty-nine isolates exhibited fungistasis against the pathogen at varying degrees. Seven species, having high growth inhibition rates (${\geq}75%$), exhibited strong antifungal activity against V. dahliae. The antifungal activity of both volatile and nonvolatile metabolites was also investigated. The nonvolatile substances produced by CEF-818 (Penicillium simplicissimum), CEF-325 (Fusarium solani), CEF-714 (Leptosphaeria sp.), and CEF-642 (Talaromyces flavus) completely inhibited V. dahliae growth. These findings deepen our understanding of cotton-endophyte interactions and provide a platform for screening G. hirsutum endophytes with biocontrol potential.

• Microbiology and Biotechnology Letters
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• v.35 no.1
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• pp.1-10
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• 2007

The 44 endophytic bacterial strains were isolated from surface-sterilized root of rice cultivated in seven different locations of Chungcheong province, Korea. Each isolate was introduced into rice seedlings grown gnotobiotically by inoculating scissor-cut first true leaf with cell suspensions, and the colonization capacity of each isolate in root tissue was analyzed at 7 days after inoculation. Sixteen out of 44 isolates were re-isolated from root successfully with the frequency of $10^{3-5}$ CFU/g tissue. Interestingly, seven out of 16 isolates were identified as Burkholderia species. The identity between inoculated strains and re-isolates was confirmed by genomic finger-printing and 16S rDNA sequence analysis. By a confocal laser scanning microscopic observation it was revealed that KJ001 strain, one of the sixteen isolates tagged with gfp colonized in root tissue especially around xylem. Six out of seven Burkholderia strains obtained in this study showed antagonizing activities against seven different fungal pathogens, contain nifH gene, and five of them enhanced growth of cucumber over 30%. The isolates showed no hypersensitive response on tobacco leaves and no pathogenecity in rice. From these results it was found that the endophytic Burkholderia strains will be useful in agriculture to develop a biocontrol agent or a bio-fertilizer.

• Korean Journal of Microbiology
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• v.47 no.4
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• pp.375-380
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• 2011

We isolated an endophytic actionmycete from root tissues of rice plant collected from paddy field near Dankook University, Cheonan, Korea. Surface sterilized roots were laid on the selective agar plates and incubated. The powdery actinomycete colonies appeared on the root surface after four weeks incubation. We isolated a strain JK-5 among them and could determine its taxonomical position as Streptomyces diastaticus subsp. ardesiacus by using 16S ribosomal DNA sequencing. The chemotaxonomical and morphological studies confirmed the taxonomical position of the strain JK-5. The shape of aerial hyphae was flexible and they contained spore chains with more than 30 smooth spherical spores per chain. Cell walls contained LL-diaminopimelic acid. There was no characteristic sugar in whole-cell hydrolysates. The major fatty acids were anteiso-15:0, anteiso-17:0 and iso-16:0. The specific menaquinones, MK-9 ($H_6$), MK-9 ($H_8$), were detected. The GC content was 72%. Antifungal activities of the strain JK-5 were relatively strong against fungal plant pathogens. The endophytic growth of the strain JK-5 was confirmed by SEM observation of the root and stem of the infected rice plant.