• Korean Journal of Microbiology
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• v.36 no.2
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• pp.97-102
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• 2000

In order to use Metarhizizmn~ anisopliae as a biological pesticide, effect of envrionmental factors on nlycelial growth, spore formation, and extracellular enzyme activity in culture broth of M. anisopliae DGUM 35001 was determined. Optimal temperature was 26^{\circ}C.$ and optimal pH ranged from 5 to 9. Among the complex media tested, MCM and SDPY media were the most favorable for mycelial growth. When Czapek-Dox agar was used as a mnimal medium, glucose and sucrose among the saccharides were very excellent source of carbohydrate. Among the biopolyners tested. chitin was the most favorable source for mycelial growth and produced high aerial inycelia. Urea and ammonium phosphate as an inorganic nitrogen source and bacto-peptone and soytone as an organic nitrogen source enhanced the mycelial growth When serine as a source of amino acid was supplemented, excellent mycelial growth was shown. Large amount of spores could be obtained from the aerial mycelia of starch medium. When the culture broth was filtrated and then the concentrate with ammonium sulfate was used as a crnde enzyme solution, high enzyme activities of amylase and protease were shown. However, lipase and chitinase activities were comparatively low.

• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.581-587
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• 1997

For bifidus fermentation food, gelatinized rice solution was fermented without liquefaction/saccharification by amylolytic Bifidobacterium spp. isolated from Korean. Eighteen amylolytic Bifidobcterium on the starch agar were isolated from 38 Korean and four strains were finally selected as good amylase producers. The most enzyme-producing strain of Bif. sp. FBD-12 secreted extracellular amylase of 0.17 U/mg and intracelluar amylase of 1.8 U/mg. Three strains of Bif. sp. FBD-12, Bif. sp. FBD-16 and Bif. sp. FBD-17 also showed good growth on pH controlled media by HCI/acetic acid to pH 5.0 while Bif. sp. FBD-6 was not so tolerant that viable cell counts reduced to $10^2\;CFU/mL$ times on the media. Initial cell number of $10^6\;CFU/mL$ for those strains reached to $10^9\;CFU/mL$ on the rice medium supplemented with yeast extract (0.2%) and cysteine (0.05%). Ascorbic acid instead of cysteine was added to the medium for improving off-flavour and the best growth was shown at 0.1% addition. Isolated soybean proteins (ISP) of 3% accelerated the growth of the strains. Maximum count of $10^9\;CFU/mL$ reached within 12 hour fermentation on the rice medium with ascorbic acid and isolated soybean protein instead of 32 hours on the cysteine medium, and total acidity increased from 0.5% to 1% on each media. Reducing sugar in the ascorbic acid/ISP cultures generally increased especially 2 mg/mL to 15.5 mg/mL for Bif. sp. FBD-6. From sensory evaluation, the products showed good acceptability so that it suggested possibility of development of bifidus-fermented rice food.

• Korean Journal of Food Science and Technology
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• v.43 no.6
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• pp.735-741
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• 2011

Bealmijang is a short-term fermented regional product that is prepared with soybean and extra ingredients. In this study, starter strain candidates were screened from Bealmijang for fermented soybean paste products. Twenty one bacterial strains producing extracellular enzymes (amylase, cellulase, protease, xylanase and lipase) were isolated from Bealmijang, buckwheat sokseongjang. The isolates were assessed for fibrinolytic and antibacterial activities, and salt tolerance. Strain HJ18-4, identified as Bacillus subtilis (AB601598) by biochemical properties (89.6%) and 16S rDNA sequencing (100%), showed the highest enzymatic, fibrinolytic, and antibacterial activities among the isolates. Although the growth of HJ18-4 was inhibited by the increase of NaCl concentration, the growth still exceeded that of B. subtilis KACC 10114 at 5% and 10% NaCl. These results suggest that B. subtilis HJ18-4 is suitable as a starter for soybean paste manufacture.

• Journal of Life Science
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• v.24 no.9
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• pp.1006-1011
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• 2014

Ginseng has been known to be highly effective for health as a traditional medicinal herb. Ginseng berry, or fruit of ginseng, contains ginsenoside, saponin, polyphenol, polyacetylene, alkaloid, etc. as the main compounds as does ginseng. The aim of this study is to evaluate any effect of ginseng berry water extract (GBE) on diabetic-associated molecules, such as enzymes, which are responsible for the glucose entry of the cells and the insulin receptor signaling molecules using HepG2 cells. Therefore, two enzymes, ${\alpha}$-amylase and ${\alpha}$-glucosidase, were selected and assayed for their activities in the presence of GBE in vitro. These two enzymes are responsible for producing glucose from dietary starch. Protein-tyrosine phosphatase 1B (PTP1B) and Akt1 are key proteins in the insulin receptor signaling pathway. These two intracellular signaling molecules were investigated for their expression levels in HepG2 cells after insulin and GBE treatment. GBE, at concentrations up to $1,000{\mu}g/ml$, did not exert any inhibitory effect on ${\alpha}$-amylase and ${\alpha}$-glucosidase. It was observed that the expression level of PTP1B was increased by insulin and the $25{\mu}g/ml$ GBE treatment enhanced the PTP1B level. However, GBE at a concentration of $200{\mu}g/ml$ reduced the expression level of PTP1B. In the case of Akt1, the Akt1 level by insulin was decreased by GBE treatment. These data suggest that the water extracts of ginseng berry have an influence on intracellular signaling by insulin.

• Journal of Microbiology and Biotechnology
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• v.19 no.4
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• pp.351-357
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• 2009

Natural wild-type strains of Bacillus subtilis are extensively used in agriculture as biocontrol agents for plants. This study examined two antagonist B. subtilis strains, KB-1111 and KB-1122, and the results illustrated that KB-1122 was a more potent inhibitor of the indicator pathogen than KB-1111. Thus, to investigate the intrinsic differences between the two antagonist strains under normal culture conditions, samples of KB-1111 and KB-1122 were analyzed using MALDI-TOF-MS. The main differences were related to 20 abundant intracellular and 17 extracellular proteins. When searching the NCBI database, a number of the differentially expressed proteins were identified, including 11 cellular proteins and 10 secretory proteins. Among these proteins, class III stress-response-related ATPase, aconitate hydratase, alpha-amylase precursor, and a secretory protein, endo-l, 4-beta-glucanase, were differentially expressed by the two strains. These results are useful to comprehend the intrinsic differences between the antagonism of KB-1111 and KB-1122.

• Mycobiology
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• v.40 no.1
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• pp.14-19
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• 2012

A $Mariannaea$ fungus was isolated during investigation of an elm tree infested with unidentified beetles. Based on morphological characteristics and molecular analysis of the internal transcribed spacer rDNA sequence, the fungus was identified as $Mariannaea$ $elegans$ var. $elegans$. Fungal growth was better on malt extract agar than on potato dextrose agar and oatmeal agar. Optimal temperature and pH for growth of the fungus were $30^{\circ}C$ and pH 7.0, respectively. The fungus was found to have the ability to produce extracellular enzymes such as amylase, ${\beta}$-glucosidase, cellulase, and protease. This is first report on $M.$ $elegans$ var. $elegans$ in Korea.

• Journal of Life Science
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• v.11 no.1
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• pp.14-21
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• 2001

To investigate the changes of carbohydrate metabolism in the senescing leaves of Zea mays during dark-induced senescence, the changes in the contents of reducing sugar, sucrose and starch as well as the activities of sucrose synthase, three isozymes of invertase, and ${\alpha}$-amylase were measured. In the senescing leaves, the content of reducing sugars temporarily increased at 4 d and rapidly decreased thereafter, whereas sucrose contents gradually decreased thereafter, whereas sucrose contents gradually decreased until 3 d of senscence and significantly decreased thereafter. The activities of intracellular invertases such as soluble acid and alkaline formed gradually enhanced until 4 d of leaf senescence and significantly declined thereafter. The extracellular invertase activity showed no significant changes during leaf senescence. The deactivation of sucrose synthase was observed within 3 d of leaf senscence. On the other hand, the starch contents gradually declined during 2 d of leaf senescence, and showed a temporary increase at 3 d, which is similar to the pattern of sucrose synthase activity., These results imply that sucrose in the senescing leaves. The major enzymes which correlated to the breakdown of sucrose during dark-induced senescence were soluble acid and alkaline invertases, not sucrose and ABA accelerated leaf senescence by inducing the accumulation of reducing sugar. These result, therefore, that leaf senescence may be mediated by the temporary quantitative changes of reducing sugar induced by the activation of intracellualr inveertases.

• Journal of Microbiology
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• v.43 no.3
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• pp.244-250
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• 2005

The effect of cytochrome $c_{550}$ encoded by cccA in Bacillus subtilis during the event of sporulation was investigated. The sporulation of cccA-overexpressing mutant was significantly accelerated, while disruptant strain showed delayed sporulation in spite of the same growth rate. Activity of sporulation stage-0-specific enzyme, extracellular $\alpha-amylase$ of mutant strains was similar to that of the control strain, but cccA-overexpressing mutant exhibited higher activity of stage-II-specific alkaline phosphatase and stage-III-specific glucose dehydrogenase when compared to deletion mutant and control strain. Northern blot analysis also revealed that cccA-overexpressing mutant showed high level of spo0A transcripts, while the disruptant rarely expressed spo0A. These results suggested that although cytochrome $c_{550}$ is dispensable for growth and sporulation, expression of cccA may play an important role for initiation of sporulation through regulation of spo0A expression.

• The Korean Journal of Mycology
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• v.48 no.2
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• pp.103-116
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• 2020

Freshwater ecosystems provide a complex environment for microorganisms. In this study, we isolated diverse fungal strains from plant litter in freshwaters. These strains were identified using molecular phylogenetic analyses of rDNA and/or other gene sequences (TUB, GAPDH, and EF1). In addition, we examined their morphological characteristics by microscopy and cultural characteristics on several media. We identified six previously unrecorded Sordariomycetes species in Korea, i.e., Colletotrichum godetiae, Discosia rubi, Robillarda sessilis, Monochaetia dimorphospora, Idriella lunata, and Phialemoniopsis endophytica. Of these, D. rubi and M. dimorphospora exhibited high extracellular amylase, lipase, and protease activities, suggesting that these fungal isolates might play an important role as decomposers in freshwater ecosystems. Plant litter could thus be a good source for isolating and investigating previously undocumented fungal species in freshwater environments.

• The Korean Journal of Mycology
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• v.46 no.3
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• pp.271-280
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• 2018

The ectomycorrhizal basidiomycete Tricholoma is one of mushroom groups that cannot be cultivated artificially. To use this mushroom as applicable resource for food production, it is necessary to obtain information about their mycelial growth properties in various environmental conditions. This study investigated the mycelial growth of four domestic isolates of Tricholoma species (T. bakamatsutake, T. fulvocastaneum, T. matsutake, T. terreum) at different physical and chemical conditions. The optimal physical conditions for their mycelia growth were found to be a temperature range of $20{\sim}25^{\circ}C$ and a pH range of 4.0~7.0 in dark condition. The growth of T. matsutake was retarded at high temperature ($30^{\circ}C$). Tests to determine the chemical factors that affected mycelial growth showed that the four Tricholoma spp. grew 1% saline. T. matsutake grew in up to 2% saline. In the presence of various heavy metals (50 ppm) and pesticides (suppliers' recommended concentration), mycelial growth was inhibited the most by cadmium and emamectin benzoate, respectively. However, all the four Tricholoma spp. grew with $Cu^+$. The growth of T. matsutake was not inhibited by abamectin, acetamiprid, and thiacloprid. Extracellular enzyme activities of amylase and ${\beta}$-glucosidase were detected only in T. bakamatsutake and T. fulvocastaneum. The results of the present study allowed us to determine suitable or harmful environmental conditions for the mycelial cultivation of the Tricholoma spp.