• Journal of Microbiology and Biotechnology
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• v.1 no.2
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• pp.126-129
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• 1991

In order to produce ${\gamma}-linolenic$ acid by Mucor sp. KCTC 8405P. the fungus was cultivated in fed-batch culture with two phases. i.e., growth in yeast-like form and induction to hyphal growth by pH shift of the culture medium during cultivation. The synchronous growth of the fungus into the appropriate sizes was important for the high density cell culture of this dimorphic fungus. Dissolved oxygen concentration in the medium did not affect degree of unsaturation of fatty acids and ${\gamma}-linolenic$ acid content. Under the culture conditions applied in this experiment. the fungus was found to produce 100 g/l dry mycelia containing 40% of the lipids, where ${\gamma}-linolenic$ acid comprised about 9% of the total extractable fatty acids.

• The Korean Journal of Mycology
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• v.21 no.1
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• pp.16-22
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• 1993

Morphological and cultural characteristics of fungi causing rice sclerotial diseases were examined. Hyphal widths of R. solani and R. oryzae were same and ranged $6.0-12.0\;{\mu}m$ with average $9.0\;{\mu}m$, the widest among those of the sclerotial fungi examined. Hyphal width of R. oryzae sativae ranged $6.0-9.0{\mu}m$ with average $7.4{\mu}m$. Hyphal width of R. cerealis was the narrowest among those of Rhizoctonia species examined, and the same was hyphal width of S. oryzae among those of Sclerotium species. Nuclear staining by HCL-Giemsa method showed that R. solani and R. oryzae had many nuclei within one hyphal cell, S. oryzae one nucleus, and the other sclerotial fungi mostly two nuclei. The nuclear number of R. solani was the largest, which ranged 2-17 with average 6.3. Average size of sclerotia of the sclerotial fungi except S. hydrophilum and S. oryzae produced in lesions ranged 1.0-2.0mm. Average size of sclerotia of S. hydrophilum and S. oryzae was 0.5mm and 0.24mm, respectively. Sclerotia of R. solani and R. oryzae produced in culture were more variable in size and larger than those produced in lesions. However, the sclerotial sizes of the other sclerotial fungi produced in culture were almost the same as those produced in lesions. Sclerotial colors of sclerotial fungi produced in lesions were similar to those produced in culture, but sclerotial shapes of some sclerotial fungi exhibited somewhat difference between the sclerotia produced in lesions and in culture. Optimum temperature for mycelial growth of R. cerealis was $23^{\circ}C$, and that of the other sclerotial fungi ranged from $27\;to\;33^{\circ}C$. Maximum temperature for mycelial growth of some sclerotial fungi was as high as $41^{\circ}C$, while that of R. cerealis was as low as $31^{\circ}C$. Minimum temperature for mycelial growth of R. cerealis was $2^{\circ}C$, and that of the other sclerotial fungi ranged from $6\;to\;10^{\circ}C$.

• Korean Journal of Organic Agriculture
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• v.23 no.1
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• pp.133-148
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• 2015

Although several adverse effects have been increased in recent years, synthetic agro-chemicals have been widely used to control diseases on paprika. This research was conducted to isolate and to characterize the antagonistic microorganism to control major paprika diseases, gray mold rot, fruit and stem rot, phytophthora blight, sclerotium rot, and wilt disease. Analysis of the fatty acid and analysis of the 16S rDNA gene sequence revealed that YKJ2 isolated in this research belongs to a group of Burkholderia cepacia. Specially, 16S rDNA gene sequence of YKJ2 showed 99% of sequence similarity with B. cepacia. Observation through the optical microscope revealed that YKJ2 was effective on suppression of the spore germination and the hyphal growth of pathogens. YKJ2 treatment on pathogens induced marked morphological changes like hyphal swelling and degradation of cell wall. In the case of phytophthora blight, the zoosporangium formation was restrained. On the basis of the results of this study, we propose that an antagonistic microorganism, B. cepacia, found in this study naming as "B. cepacia strain YKJ2" and has great potential as one of biological control agents against major diseases of paprika.

• Journal of Microbiology
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• v.41 no.2
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• pp.121-128
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• 2003

The identification of genes involved in true hypha formation is important in the study of mechanisms underlying the morphogenetic switch in yeast. We isolated a gene responsible for the morphogenetic switch in Yarrowia lipolytica, which forms true hyphae in response to serum or N-acetylglucosamine. The isolated gene, encoding 847 amino acids, had sequence identities of 27% and 25% with the Bud6 (Aip3) proteins of Saccharomyces cerevisiae and Schizosaccharomyces pombe, respectively. Disruption of this gene, designated YIBUD6, in haploid and diploid strains significantly reduced the ability of Y. lipolytica to switch from the yeast form to the hyphal form in hypha-inducing media. It was also found that YIBud6$\Delta$ mutants were rounder than the wild type when grown in the yeast form. These results indicate that the YIBud6 protein is necessary for hyphal growth and cell polarity in both haploid and diploid Y. lipolytica cells.

• The Plant Pathology Journal
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• v.33 no.4
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• pp.362-369
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• 2017

White root rot disease, caused by the pathogen Rosellinia necatrix, is one of the world's most devastating plant fungal diseases and affects several commercially important species of fruit trees and crops. Recent global outbreaks of R. necatrix and advances in molecular techniques have both increased interest in this pathogen. However, the lack of information regarding the genomic structure and transcriptome of R. necatrix has been a barrier to the progress of functional genomic research and the control of this harmful pathogen. Here, we identified 10,616 novel full-length transcripts from the filamentous hyphal tissue of R. necatrix (KACC 40445 strain) using PacBio single-molecule sequencing technology. After annotation of the unigene sets, we selected 14 cell cycle-related genes, which are likely either positively or negatively involved in hyphal growth by cell cycle control. The expression of the selected genes was further compared between two strains that displayed different growth rates on nutritional media. Furthermore, we predicted pathogen-related effector genes and cell wall-degrading enzymes from the annotated gene sets. These results provide the most comprehensive transcriptomal resources for R. necatrix, and could facilitate functional genomics and further analyses of this important phytopathogen.

• Journal of Microbiology and Biotechnology
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• v.31 no.6
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• pp.815-822
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• 2021

Indigenous fungus-feeding nematodes may adversely affect the growth and activity of introduced biocontrol fungi. Alginate pellets of the biocontrol fungus Trichoderma harzianum ThzID1-M3 and sclerotia of the fungal plant pathogen Sclerotinia sclerotiorum were added to nonsterile soil at a soil water potential of -50 or -1,000 kPa. The biomass of ThzID1-M3, nematode populations, and extent of colonization of sclerotia by ThzID1-M3 were monitored over time. The presence of ThzID1-M3 increased the nematode population under both moisture regimes (p < 0.05), and fungivores comprised 69-75% of the nematode population. By day 5, the biomass of ThzID1-M3b and its colonization of sclerotia increased and were strongly correlated (R² = 0.98), followed by a rapid reduction, under both regimes. At -50 kPa (the wetter of the two environments), fungal biomass and colonization by ThzID1-M3 were less, in the period from 5 to 20 days, while fungivores were more abundant. These results indicate that ThzID1-M3 stimulated the population growth of fungivorous nematodes, which in turn, reduced the biocontrol ability of the fungus to mycoparasitize sclerotia. However, colonization incidence reached 100% by day 5 and remained so for the experimental period under both regimes, although hyphal fragments disappeared by day 20. Our results suggest that indigenous fungivores are an important constraint for the biocontrol activity of introduced fungi, and sclerotia can provide spatial refuge for biocontrol fungi from the feeding activity of fungivorous nematodes.

• KSBB Journal
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• v.27 no.5
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• pp.301-307
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• 2012

The hyphal growth, production of color pigments and monacolin K by Monascus strains were investigated in liquid medium. Thirty five different strains were collected and cultured in potato dextrose yeast extract broth (PDYB), potato dextrose broth (PDB) and malt extract broth (MEB) medea at $25^{\circ}C$ for 7 days. The growth rates of most of strains were highest in PDYB medium. Growth rate as well as pigment production were influenced by suspension conditions of mycelia during liquid cultivation. Most of strains producing monacolin K corresponded to strains producing red pigment highly and showing more pH changes of liquid media. Monacolin K produced from strains was detected in culture broth as well as mycelia. Any citrinin was not detected in monacolin K producing strains. These results imply that the selection of the strains producing red pigment highly and showing more pH changes in liquid cultivation could be applied for primary screening of Monascus strains for preparation of red mold rice.

• KSBB Journal
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• v.4 no.3
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• pp.241-245
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• 1989

A carriersupported mycelial growth of Sreptomyces erythreus was applied to erythromycin fermentation sistem using celite as a support material. Hyphal growth through the pore matrices of the materials showed anchorages and provided a stable biofilm growth. When the phospate concentration was limited to 0.8g corn steep liquor/L(corresponding to 40mg KH2PO4/L), the specific production rate of erythromycin was increased from 557$\mu$g/g-cell.hr under unlimited condition to 2, 898 $\mu$g/g-cell.hr. A fluidized-bed bioreactor was operated for erythromycin production by a repeated fed-batch mode. The control of free mycelial concentration and the extension of production phase were considered important to maintain the reactor productivity at a desired level. The erythromycin production under phosphate-limited condition could be maintained for at least 600hrs.

• Journal of Microbiology and Biotechnology
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• v.18 no.1
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• pp.167-170
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• 2008

A fungal strain BCP, which parasitizes Botrytis cinerea gray mold pathogen, was isolated and identified as Acremonium strictum. BCP strain overgrew the colonies of B. cinerea and caused severe lysis of the host hyphae. Frequent penetration and hyphal growth of A. strictum BCP inside the mycelia of B. cinerea were observed under light microscopy. In addition, some morphological abnormalities such as granulation and vacuolation of the cytoplasm were observed in mycelia and spores of B. cinerea. In dual culture test, A. strictum BCP strongly inhibited the mycelial growth of several plant pathogenic fungi as well as B. cinerea. To our knowledge, this is the first report on mycoparasitism of Acremonium species on B. cinerea.

• Journal of Microbiology and Biotechnology
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• v.9 no.3
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• pp.352-357
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• 1999

Enterobacter sp. B54 inhibited growth of the fungus Phytophthora capsici on potato dextrose agar (PDA). Three mutants with antifungal activities (denoted M54-47, M54-113, and M54-329) which were lost or increased, through Pl::Tn5 lac mutagenesis, were used to isolate genes responsible for fungal inhibition on PDA. Two clones were selected from the partially EcoR1-digested genomic library of the wild-type strain by probing with genomic flanking sequences of each mutant. We have isolated a 20-kb EcoR1 genomic DNA fragment from this strain that contains genes involved in hyphal growth inhibition of P. capsici on PDA. Subcloning and expression analysis of the above DNA fragment identified a 8-kb region which was necessary for antifungal activities. A 8-kb HindⅢDNA fragment covers three genomic loci inserted by Tn5 lac in each mutant. This suggested that all genes which are related to antifungal activities might be clustered in simple forms of at least 5-8 kb sizes.