• Mycobiology
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• v.34 no.4
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• pp.219-229
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• 2006

Seventeen microbial species including 10 fungal taxa, two yeasts and five bacteria, were isolated from freshly prepared orange, guava and banana juices kept in open bottles at room temperature for 7 days. Eight different essential oils, from local herbs, were tested for their antimicrobial activity against these test organisms. The essential oils of Cymbopogon citratus, Ocimum basilicum and Origanum majorana were found to be highly effective against these microorganisms. Aspergillus niger, A. flavus and Saccharomyces cerevisiae, the most prevalent microorganisms in juice, showed the highest resistance against these essential oils. GC-MS analysis showed that while e-citral, a'-myrcene, and z-citral represent the major components (75.1 %) of the essential oil of Cymbopogon citratus; bezynen,l-methyl-4-(2-propenyl), 1,8-cineole and trans-a'-bisabolene were the main components (90.6%) of Ocimum basilicum; whereas 3-cyclohexen-l-0l,4-methyl-l(l-methylethyl)-(CAS), c-terpinene and trans-caryophyllene represent the major components (65.1%) of Origanum majorana. These three essential oils were introduced into juices by two techniques namely, fumigation and direct contact. The former technique showed more fungicidal effect than the latter one against A. flavus, A. niger, and S. cerevisiae. The essential oil of Cymbopogon citratus by comparison to other test oils showed the strongest effect against these fungi with a minimum inhibitory concentration of $1.5\;{\mu}l/ml$ medium and a sublethal concentration of $1.0\;{\mu}l/ml$. The antimicrobial activity of this oil is thermostable at $121^{\circ}C$ for 30 min.

• Applied Biological Chemistry
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• v.7
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• pp.53-58
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• 1966

A study was carried out to investigate the microorganisms and their floral changes during the tobacco fermentation. The results were sumarized as follows. I. The molds in the "tobacco leaves" were isolated and identified as follows; Aspergllus flavus Link, A. restrictus G. Smith, A. nidulans (Eidam) Wint, A. awamori, Oidium sp. Edmundmasonia sp. Spicaria sp. II. The bacteria in the tobacco were isolated and identified as follows; Bacillus subtilis, B. subtilis var aterriums. B. licheniformis, B. cereus, B. Pumilus, B. megaterium, Flavobacterium harrisonii, Aerobacter aerogenes. III. The counts of the microorganisms on leaves taken from bulks of the fermenting leaf tobacco revealed the presence of relatively small number on the initial stage of the fermentation. During the tobacco fermentation the number of molds increase gradually to the maximum until the 14 th. day of the fermenation, followed by showing, the plateau, and the bacteria population revealed the maximum on the 7 th. day, then declined slowly.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.1
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• pp.15-21
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• 2016

Aspergillus is the most common opportunistic fungus causing infection. Aspergillus is the most morphologically identified in the laboratory. Recently, molecular genetic methods have been proposed for identification of fungi that unidentified morphologically or identified genus level. Of 475 cases of Aspergillus isolated from clinical specimens, there were Aspergillus fumigatus 257 (54.1%), A. niger 101 (21.3%), A. flavus 43 (9.1%), A. terreus 29 (6.1%), Aspergillus nidulans 2 (0.4%), Aspergillus clavatus 1 (0.2%), and the Aspergillus species 42 (8.8%). Eleven cases of unidentified or identified at the genus level included Aspergillus fumigatus 5, Aspergillus falvus 1, Aspergillus terreus 1, and Aspergillus lentulus 1 was identified in the sequencing of the strain level. It was identified as Aspergillus versicolor 2, and Emericella parvathecia 1. 92.2% of Aspergillus was identified as a possible morphological, 8.8% could not be identified at the species level. Sequence-based molecular analysis using the ITS and D1D2 is considered useful for identification of the species level.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.53-60
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• 2000

Strain BH5 was isolated from naturally fermented Kimchi and identified as a bacteriocin producer, which has bactericidal activity against Micrococcus flavus ATCC 10240. Strain BH5 was identified tentatively as Lactococcus lactis by the API test and some characteristics. Lactococcus lactis BH5 showed a broad spectrum of activity against most of the non-pathogenic and pathogenic microorganisms tested by the modified deferred method. The activity of lacticin BH5, named tentatively as the bacteriocin produced by Lactococcus lactis BH5, was detected at the mid-log growth phase, reached its maximum during the early stationary phase, and decreased after the late stationary phase. Lacticin BH5 also showed a relatively broad spectrum of activity against non-pathogenic and pathogenic microorganisms as tested by the spot-on-lawn method. Its antimicrobial activity on sensitive indicator cells was completely disappeared by protease XIV or ${\alpha}$-chymotrypsin. The inhibitory activities of lacticin BH5 were detected during treatments up to 100$^{\circ}C$ for 30 min. Lacticin BH5 was very stable over a pH range of 2.0 to 9.0 and was stable with all the organic solvents examined. The cell concentration and bacteriocin production in strain BH5 were maximum when grown at 30$^{\circ}C$ in a modified MRS medium supplemented with 0.5% tryptone, 1.0% yeast extract, and 0.5% beef extract as nitrogen sources. It demonstrated a typical bactericidal mode of inhibition against Micrococcus flavus ATCC 10240. Lacticin BH5 was purified through ammonium sulfate precipitation, ethanol precipitation, and CM-Sepharose column chromatography. The apparent molecular mass of lacticin BH5 was estimated to be in the region of 3.7 kDa, by the direct detection of bactericidal activity after SDS-PAGE. Mutant strain NO141 which was isolated by nitrosoguanidine mutagenesis produced about 4 fold more bacteriocin than the wild type.

• Journal of the korean veterinary medical association
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• v.26 no.9
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• pp.543-553
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• 1990

This report describes the cellular changes induced in the livers of ducklings by a sin91e administration of aflatoxin B$_1$ produced by Korean Industrial Strain of the Aspergillus flavus, in order to examine the toxicity of the minimum dose of

• Applied Biological Chemistry
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• v.41 no.3
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• pp.219-223
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• 1998

We have established a transformation system for entomopathogenic fungus, Metarhizium anisopliae, in order to develop mycoinsecticide by recombinant DNA techniques. Protoplasts of M. anisopliae would be transformed to a benomyl-resistant by introducing pBRG-4 plasmid DNA, which contains a ${\beta}-tubulin$ gene of Aspergillus flavus conferring resistance to benomyl and a pyr4 gene of Neurospora crassa, in the presence of 5% polyethylene glycol and 10 mM calcium chloride. Transformants occuring at a frequency of 10 colonies per $50\;{\mu}g$ pBRG-4 DNA grew on the $5\;{\mu}g/ml$ concentrations of benamyl, while the wild type was inhibited by $2.5\;{\mu}g/ml$. From the Southern analysis using genomic DNAs isolated from M. anisopliae transformants, the positive signals suggested that the ${\beta}-tubulin$ gene had integrated in the M. anisopliae genome by homologous recombination.

• Food Science and Biotechnology
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• v.17 no.2
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• pp.442-445
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• 2008

Meju, a major ingredient of doenjang which is a popular Korean traditional fermented soyfood, was manufactured by fermenting steamed soybeans in natural environment in which steamed soy was exposed to airborne microorganism, in particular, fungi. Total isoflavone content was reduced from 1,849 mg/kg of cooked soy to 816 mg/kg of meju at the $90^{th}$ day of fermentation. Total glycosides and aglycones of isoflavones in meju were 1,827 and 22 mg/kg at 0 day and changed into 487 and 329 mg/kg at the 90th day of fermentation, respectively. Meanwhile, the ratio of glycosides to aglycones of isoflavones was not changed during aging of doenjang but remained relatively constant with 592 and 644 mg/kg aglycones at the 0 and $160^{th}$ day, respectively. When cooked soy was fermented with Aspergillus oryzae and Aspergillus flavus, isoflavone profiles were significantly different from each other while A. oryzae caused more extensive metabolism of isoflavones than A. flavus.

• The Plant Pathology Journal
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• v.24 no.1
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• pp.74-79
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• 2008

This research was conducted to evaluate fungal and bacterial populations in unhulled and brown rice under indoor storage conditions, and to examine the relationship between microbial populations and environmental conditions such as temperature and relative humidity. The temperature and relative humidity of the storage room ranged from $22.6^{\circ}C\;to\;27.0^{\circ}C$ and 23.3% to 44.2%, respectively. Total fungal and bacterial populations remained relatively stable over the storage period. Predominant fungi included Aspergillus candidus, A. flavus, A. fumigatus, and Penicillium spp.; the predominant bacteria were Bacillus, Microbacterium, Sphingomonas, and Methylobacterium spp. Total fungi and bacteria were not significantly correlated with either unhulled (r=0.448, P=0.372) or brown (r=0.466, P=0.351) rice. In unhulled rice, total fungi showed positive correlations with total Aspergillus (r=0.994, P<0.001) and total Penicillium (r=0.906, P<0.05); A. flavus was positively correlated with total Aspergillus (r=0.913, P<0.05) and total fungi (r=0.868, P<0.05). In brown rice, Bacillus spp. was also positively correlated with total bacteria (r=0.998, P<0.001). Mean temperature was negatively correlated with A. candidus (r=-0.852, P<0.05) and total fungi (r=-0.961, P<0.01), and mean relative humidity was positively correlated with total Penicillium spp.(r=0.884, P<0.05) in brown rice. Hence these results could provide basic information on the fungal and bacterial populations in unhulled and brown rice stored under room conditions, and on the effect of environmental conditions on the populations of fungi and bacteria, especially Aspergillus and Penicillium spp.

• Food Science and Preservation
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• v.30 no.1
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• pp.28-41
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• 2023

Non-aflatoxigenic Aspergillus oryzae and aflatoxigenic A. flavus cannot be clearly identified by partial sequencing of the internal transcribed spacer (ITS) and 18S ribosomal ribonucleic acid (18S rRNA) regions. This study aimed to compare the accuracy among three aflatoxin detection methods using ultra-performance liquid chromatography (UPLC), high-performance liquid chromatography (HPLC), and an enzyme-linked immunosorbent assay (ELISA) kit and to select the non-aflatoxigenic Aspergillus sp. isolated from soybean paste. All analytical methods were suitable according to the international standards of Codex Alimentarius FAO-WHO (CODEX) or the Ministry of Food and Drug Safety (MFDS). UPLC exhibited the best of limit of detection (LOD) and limit of quantification (LOQ). Based on UPLC, HPLC, and the ELISA kit assay, the P5 and P7 strains isolated from soybean paste had 1,663.49, 1,468.12, and >20 ㎍/kg and 1,470.08, 1,056.73, and >20 ㎍/kg, respectively, detected and re-identified as A. flavus. In contrast, the P3 and P4 strains (A. oryzae), which were detected below the MFDS standards in all assays, were confirmed as non-aflatoxigenic fungi. Among the methods evaluated for quantitative analysis of aflatoxin, UPLC and HPLC are superior in terms of accuracy, and the ELISA kit rapidly detects low concentrations of aflatoxin. Furthermore, this study demonstrates that any Aspergillus sp. isolated for use as a fermentation starter should be analyzed for potential aflatoxin production using UPLC and HPLC for accurate quantitative analysis or ELISA for the rapid detection of low-level concentrations of aflatoxin.

• Korean journal of applied entomology
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• v.52 no.4
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• pp.403-408
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• 2013

A survey of pest occurrence and status of farmer's pest management was conducted at 45 cymbidium farms in 10 major cultivation areas in Korea. The pest species collected from the cymbidium farms were identified as follows: Tetranychus urticae Koch, Frankliniella intonsa Trybom, Pinnaspis aspidistrae Signoret, Incilaria confusa Cockarel, Halyomorpha brevis Walker, Myzus persicae S$\ddot{u}$lzer, and Aphis gossypii Glover, Coccus hesperidum Linnaeus, Thrips flavus Schrank, and Thrips tabaci Lindeman. The two-spotted spider mite, T. urticae, was the key pest in cymbidium production, occurring on 45 farms, followed by scales (20 farms), slugs (6), thrips (8), aphids (5), and stinkbug (1). PCR-RFLP of the rDNA ITS2 region revealed that two thrips species, Thrips flavus Schrank and Thrips tabaci Lindeman, occur on cymbidium farms. Therefore, it is necessary for the cymbidium farmers to establish an integrated pest management system to meet quarantine standards.