• Journal of Life Science
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• v.16 no.3 s.76
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• pp.454-458
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• 2006

HSF1 is the heat shock transcription factor in Saccharomyces cerevisiae. S. cerevisiae KNU5377 can ferment at high temperature such as $40^{\b{o}}C$. We have been the subjects of intense study because Hsf1p mediates gene expression not only to heat shock, but to a variety of cellular and environmental stress challenges. Basing these facts, we firstly tried to construct the hsf1 gene-deleted mutant. PCR-method for fast production of gene disruption cassette was introduced in a thermotolerant yeast S. cerevisiae KNU5377, which allowed the addition of short flanking homology region as short as 45 bp suffice to mediate homologous recombination to kanMX module. Such a cassette is composed of linking genomic DNA of target gene to the selectable marker kanMX4 that confers geneticin (G418) resistance in yeast. That module is extensively used for PCR-based gene replacement of target gene in the laboratory strains. We describe here the generation of hsf1 gene disruption construction using PCR product of selectable marker with primers that provide homology to the hsf1 gene following separation of haploid strain in wild type yeast S. cerevisiae KNU5377. Yeast deletion overview containing replace cassette module, deletion mutant construction and strain confirmation in this study used Saccharomyces Genome Deletion Project (http:://www-sequence.standard.edu/group/yeast_deletion_project). This mutant by genetic manipulation of wild type yeast KNU5377 strain will provide a good system for analyzing the research of the molecular biology underlying their physiology and metabolic process under fermentation and improvement of their fermentative properties.

• Journal of Bio-Environment Control
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• v.29 no.1
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• pp.96-102
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• 2020

Fusarium wilt caused by Fusarium oxysporum is a devastating disease limiting production of watermelon in Korea. The best way to control diseases is to use resistant gourd rootstock on watermelon. This study was conducted to establish an efficient screening method for resistant bottle gourd to Fusarium oxysporum f. sp. lagenaria. To develop an efficient inoculation method, incubation temperature after inoculation (15, 20, 25, and 30℃), inoculum concentration (1 × 10⁵, 5 × 10⁵, 1 × 10⁶, and 5 × 10⁶ conidia·mL^-1), and growth stages of seedlings (7, 10, 13, and 16 days) was investigated. Disease development of Fusarium wilt of bottle gourd was little affected by differences in incubation temperature and growth stages of seedlings. But resistant lines were more susceptible and appeared more severe symptoms at the higher inoculation level. Taken together, we suggest that an effective screening method for resistant gourd plant to Fusarium wilt is to dip the roots of 10-day old seedlings in spore suspension of 1 × 10⁵ - 1 × 10⁶ conidia·mL^-1, for 30 min, to transplant the seedlings into a non-infected soil, and then to incubate the inoculated plants in a growth room at 25℃ for 3 weeks to develop Fusarium wilt.

• Journal of Mushroom
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• v.11 no.1
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• pp.1-8
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• 2013

In this study, twelve of Lepista nuda were collected from various localities in Korea. Also thirteen exotic L. nuda species were collected from Japan, France, Switzerland and Portugal. Spores were isolated under optical microscope. These spores were placed on the surface of YM medium for inducing to germination. Eleven mating-groups were selected by morphological characters of fruit body such as size, color and stipe patterns. Intra-isolate crosses were made between two single-spore isolates derived from mating-groups. Also, dikaryotic crossing using the isolates from L. nuda were carried out to evaluated tetrakaryon formation. Cross-mating compatibility tests also verified its dikaryotic state by microscopic or molecular genetic observation of clamp connection and Random Amplified Polymorphic DNA (RAPD) band pattern. To analyze the growth rate of hybrids and parents mycelium in dikaryons obtained from compatible mating groups were placed on PDA medium. Intra-isolate crosses determined eleven mating-groups within L. nuda. The typical clamp connection were mostly observed in mating-groups of Korean L. nuda in $K1{\times}K2$, $K1{\times}K3$, $K1{\times}K4$, $K1{\times}K6$, $K1{\times}K5$, $K2{\times}K4$, $K2{\times}K3$, $K2{\times}K6$, $K3{\times}K4$, $K4{\times}K5$, and $K4{\times}K6$. Korean L. nuda type of dikaryon, shown to cross-incompatibility with L. sordida, it seemed that mating induce more rapidly than wild types in a view of growth rate. In conclusion, it would be useful to improve mass production with better morphological characteristics through a special mating of L. nuda.

• Microbiology and Biotechnology Letters
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• v.35 no.4
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• pp.325-333
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• 2007

One bacterium with high proteinase production and spore-forming ability was isolated from korean traditional soybean paste(doenjang). The isolated strain was identified as Bacillus subtilis, based on gram-staining, biochemical properties and l6S rRNA gene sequencing, and designated as B. subtilis DJI. Its growth rate was very fast, and it reached its stationary phase within 9 h, and then started to form spores. Bacterial-koji and doenjang were prepared using B. subtilis DJI. Chemical components of the doenjang were determined after 2 months of aging period: amino nitrogen 507 mg%, crude protein 14.3%, crude fat 4.8% and water 54.9%. The composition of total and free amino acids and their ratios of doenjang were changed during the aging period. Among total amino acids in DJI doenjang, glutamic acid, aspartic acid, leucine and arginine were the major amino acids. The fibrinolytic activities of DJI doenjang and traditional doenjangs were 909.7 units/ml and $363.3{\sim}618.6\;units/ml$, respectively. Flavor compounds of DJI doenjang and traditional doenjang were extracted by SDE(simultaneous steam distillation and extraction), and analyzed by GC/MS; DJI doenjang possessed the typically favorable flavor compounds in traditional korean doenjang, with reduced off-flavor compounds.

• Research in Plant Disease
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• v.12 no.3
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• pp.240-248
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• 2006

Control of white rot which is one of the most serious apple diseases in Korea has mainly relied on periodical spray of protective fungicides. As the main inoculum source of the disease is pycnidiospores produced in the warts formed on affected stems of apple tree, it can be conceivable that inhibition of spore production might be an effective means for controlling the disease. Inhibitory efficacy of eight selected fungicides against sporulation of the fungus was assessed by counting the number of spores produced at detached warts treated with the fungicides of recommended dilution. They showed diverse effect on sporulation. Carbendazim and azoxystrobin suppressed sporulation almost completely, the former irreversively. Thiram and folpet promoted sporulation as producing much more number of spores than untreated control. Others showed almost no effect on sporulation. Effects of suppression and promotion in the sporulation shown by the fungicides on the control of white rot were examined by incidences of disease and infection at the plots adopted the spray programs of which the fungicide at late May was substituted by carbendazim, azoxystrobin, folpet and thiram, respectively. Disease incidence and infection frequency at the plots sprayed former two chemicals which suppressed sporulation were much lower than those of the plots adopted latter two chemicals and untreated plot at which the fungicide spray was skipped at that time. These facts were reconfirmed in the experiments conducted with carbendazim and thiram, in which 100 fruits were bagged just prior to each spray from late May to late July for elucidating the effect of the two fungicides on the action of subsequent ones. Disease incidence and infection frequency on the fruit bagged just prior to each spray were gradually increased as the seasons going on. The increase rate at the carbendazim plot was much lower than that of thiram. Especially, the fruit infected till late July at the carbendazim plot were almost completely cured by the three fungicides, iminoctadine-triacetate, tebuconazole and samzinwang, a combined formular of iminoctadine-triacetate and difenoconazole, sprayed at late July and hence. In thiram plot, infected fruit were also cured by the 3 fungicides but not remarkable. From these results, it can be concluded that control efficiency of white rot can be greatly enhanced by selecting the fungicide capable of suppress the sporulation of white rot fungus at the season when the mass dispersal of spores is not initiated.

• Microbiology and Biotechnology Letters
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• v.11 no.3
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• pp.205-210
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• 1983

Extracellular $\beta$-galactosidase was prepared from a culture of Lactobacillus sporogenes, a spore-forming lactic acid bacterium. The enzyme functioned optimally at pH 6.8 and at 6$0^{\circ}C$ o-nitrophenyl-$\beta$-D-galactopyranoside (ONPG) in 0.05M sodium phosphate buffer. The activation energy of the enzymatic hydrolysis of ONPG was about 16,000 cal/mole below $50^{\circ}C$ and 11,300 cal/mole above the temperature. It was fairly stable over a pH range from 4.0 to 8.0 losing only less than 30% of its activity after hearting at 6$0^{\circ}C$ and pH 6.8 for 3 hours. Metal ions showed no significant effect on the enzyme activity, whereas L-cysteine exerted a slight stimulatory effect at the concentration of 10mM. The km values were 1.48mM for ONPG and 64.5mM for lactose. Hydrolysis of ONPG by the enzyme was product-inhibited by galactose (Ki=13.3mM, competitive inhibition) and by glucose(Ki= 11.4mM, uncompetitive type). The enzyme activity was also noncompetitively inhibited in the presence of lactose (Ki= 17.8mM).

• Research in Plant Disease
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• v.23 no.2
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• pp.177-185
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• 2017

Bacillus amyloliquefaciens LM11 was isolated from the feces of larvae of the rhino beetle and showed strong antifungal activities against various phytopathogenic fungi by producing biosurfactants. In this study, our overall goal was to determine relationship between biosurfactants produced from the LM11 strain and its role in growth inhibition of phytopathogenic fungi. Production and expression levels of B. amyloliquefaciens LM11 biosurfactants were significantly differed depending on growth phases. Transcriptional and biochemical analysis indicated that the biosurfactants of the LM11 strain were greatly enhanced in late log-phase to stationary phase. Inhibitions of phytopathogenic mycelial growth and spore germination were directly correlated (P<0.001, R=0.761) with concentrations of the LM11 cell-free culture filtrates. The minimum inhibitory surface tension of the culture filtrate of the B. amyloliquefaciens LM11 grown in stationary phase to inhibit mycelial growth of the phytopathogenic fungi was 38.5 mN/m (P<0.001, R=0.951-0.977). Our results indicated that the biosurfactants of B. amyloliquefaciens LM11 act as key antifungal metabolites in biocontrol of plant diseases, and measuring surface tension of the cell-free culture fluids can be used as an easy indicator for optimal usage of the biocontrol agents.

• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.11-11
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• 2014

Fungal pathogens have huge impact on health and economic wellbeing of human by causing life-threatening mycoses in immune-compromised patients or by destroying crop plants. A key determinant of fungal pathogenesis is their ability to undergo developmental change in response to host or environmental factors. Genetic pathways that regulate such morphological transitions and adaptation are therefore extensively studied during the last few decades. Given that epigenetic as well as genetic components play pivotal roles in development of plants and mammals, contribution of microbial epigenetic counterparts to this morphogenetic process is intriguing yet nearly unappreciated question to date. To bridge this gap in our knowledge, we set out to investigate histone modifications among epigenetic mechanisms that possibly regulate fungal adaptation and processes involved in pathogenesis of a model plant pathogenic fungus, Magnaporthe oryzae. M. oryzae is a causal agent of rice blast disease, which destroys 10 to 30% of the rice crop annually. Since the rice is the staple food for more than half of human population, the disease is a major threat to global food security. In addition to the socioeconomic impact of the disease it causes, the fungus is genetically tractable and can undergo well-defined morphological transitions including asexual spore production and appressorium (a specialized infection structure) formation in vitro, making it a model to study fungal development and pathogenicity. For functional and comparative analysis of histone modifications, a web-based database (dbHiMo) was constructed to archive and analyze histone modifying enzymes from eukaryotic species whose genome sequences are available. Histone modifying enzymes were identified applying a search pipeline built upon profile hidden Markov model (HMM) to proteomes. The database incorporates 22,169 histone-modifying enzymes identified from 342 species including 214 fungal, 33 plants, and 77 metazoan species. The dbHiMo provides users with web-based personalized data browsing and analysis tools, supporting comparative and evolutionary genomics. Based on the database entries, functional analysis of genes encoding histone acetyltransferases and histone demethylases is under way. Here I provide examples of such analyses that show how histone acetylation and methylation is implicated in regulating important aspects of fungal pathogenesis. Current analysis of histone modifying enzymes will be followed by ChIP-Seq and RNA-seq experiments to pinpoint the genes that are controlled by particular histone modifications. We anticipate that our work will provide not only the significant advances in our understanding of epigenetic mechanisms operating in microbial eukaryotes but also basis to expand our perspective on regulation of development in fungal pathogens.

• Microbiology and Biotechnology Letters
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• v.35 no.2
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• pp.128-134
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• 2007

Previously, we isolated plant growth promoting rhizobacterium (PGPR) Bacillus licheniformis K11 which could produce auxin, cellulase and siderophore. The siderophore of B. licheniformis K11 $(siderophore_{K11})$ was determined to be a catechol type siderophore which is produced generally by Bacillus spp. B. licheniformis K11 could produce the siderophore most highly after 96 h of incubation under nutrient broth at $20^{\circ}C$ with initial pH 9.0. For the production of the $siderophore_{K11}$, trehalose and $NH_4Cl$ were the best carbon and nitrogen sources in Davis minimal medium, respectively. The $siderophore_{K11}$ was Produced in M9 medium (pH 9.0) after 4 days at $20^{\circ}C$, and purified from culture broth of B. licheniformis K11 by using Amberlite XAD-2, Sephadex LH-20 column chromatography, and reversed-phase HPLC. The $siderophore_{K11}$ had the biocontrol activity against spore germination of P. capsici and F. oxysporum on potato dextrose agar (PDA). The results indicate that the $siderophore_{K11}$ is an antifungal mechanism of B. licheniformis K11 against phytopathogenic fungi.

• Korean journal of applied entomology
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• v.26 no.3 s.72
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• pp.171-178
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• 1987

Pathogenic isolates of Alternaria mali produced host-specific toxin(AM-toxin) in liquid culture. The toxin was also released by germinating spores of the fungus. The physiological event of apple leaves induced by germinating spores was an increased loss of electrolytes from susceptible leaves. This reaction was evident soon after spore inoculation, indicating that the leakage was caused by AM-toxin from germinating spores. Typical symptoms were developed only in susceptible leaves of apple within 48hr after inoculation with pathogenic spores. Similar symptoms occurred on susceptible leaves when non-pathogenic isolates plus AM-toxin were used.