• 한국잠사곤충학회지
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• 제7권
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• pp.53-63
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• 1967

본 실험은 한국산 잠견에 기생하는 세균을 분리하여 생리학적 형태학적 및 배양적인 특성을 파악하여 그 미생물을 동정하고 저장중인 잠견에 미생물 침식을 방지하는 과학적인 근거를 모색했다. 그 실험결과는 다음과 같다. 1. 잠견으로부터 분리된 12 strain의 Bacteria의 형태학적인 실험결과 colony의 형태는 table II와 같다. 종합적인 형태적 특성은 table III과 같으며 gram stain과 spore stain은 Fig, I, II와 같다. 2. 분리된 12 strain의 배양적인 특성은 table IV, V, Ⅵ와 같다. 3. 분리된 12 strain의 생리적인 특성은 table Ⅶ와 같다. 4. 이상, 형태학적 배양적 생리적인 특성에 의거하여 분리균주의 유연관계를 추정하면 다음과 같다. (l) No 1 No 8; Bacillus subtilis variation (2) No 2 ; Bacillus stearothermophilus (3) No 3 ; Bacillus circulans (4) No 5 No 6; Bacillus thuringiensis (5) No 7 No 11; Bacillus brevis (6) No 12 No l0; Bacillus cereus variation

• Journal of Microbiology and Biotechnology
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• 제29권2호
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• pp.209-221
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• 2019

Gamma-aminobutyric acid (GABA) is a neurotransmitter that exerts several physiological functions and positive effects on human health. The aim of this study was to isolate and characterize the strains that had GABA-producing abilities from various fermented fish products. A total of 91 acid-producing strains were isolated from 41 samples of fermented fish products, and 27 strains showing GABA-producing abilities were identified by the 16S rDNA sequences. Among the strains, 31% strains tolerated at high-salt environment of 10-20% throughout the fermentation of fish sauces. The 27 isolates that produced GABA at various concentrations did so in the range of 5 to 454 mM. These GABA-producing isolates were identified as lactic acid bacteria of 14 strains, which included twelve Lactococcus lactis, one Enterococcus faecium, and one Lactococcus pentosus; eight Bacillus cereus group, which included seven B. thuringiensis and one B. cereus; and five Staphylococcus spp. Interestingly, with Vietnamese fish sauces, we mostly identified species of B. thuringiensis and Staphylococcus spp., while with Korean fermented fish products, the majority of the strains identified belonged to L. lactis. Among the strains, B. thuringiensis LH2134 produced the highest levels of GABA at 366 mM among the strains identified from Vietnamese fish sauces, whereas L. lactis LA43, a new strain isolated from Korean jeotgal (salted shrimp paste), produced the highest amount of GABA at 454 mM and the glutamate concentration in the medium was essential for GABA accumulation. Therefore, such the isolates might serve as good starters for development of more GABA-reinforced foods among fermented fish products.

• Food Science and Biotechnology
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• 제17권1호
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• pp.123-129
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• 2008

To isolate Bacillus cereus presenting at a level of 5 log CFU/g in kochujang, a primary dilution ($10^{-1}$) of kochujang was heated at $85^{\circ}C$ for 5 min. Two isolated strains Voges-Proskauer positive colony (KBC) and a negative colony (KBM) were identified as B. cereus and Bacillus mycoides, respectively, by biochemical test and 16S rDNA sequencing. $D_{100^{\circ}C}$-Values of KBC and KBM strains was 8.37 and 7.08 min, respectively. When spores of KBC strain were inoculated to kochujang at the level of 4-5 log spores/g, the number of spores was no significant difference (p<0.05) for each sample from 1 up to 60 day of aging. When kochujang was inoculated with 4 log spores/g and heated at $85^{\circ}C$ for 15 min, the number of spores was similar to that of unheated kochujang. Therefore, we estimated that B. cereus isolated from kochujang resistant on the heat treatment ($85^{\circ}C$, 15 min) and its heat resistance characteristics could be used to count the number in kochtjang.

• 한국식품영양과학회지
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• 제33권2호
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• pp.439-442
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• 2004

재래식 된장으로부터 혈전용해능과 $\beta$-glucosidase효소를 생산하는 미생물을 분리하였으며, 분리한 균의 형태학적, 생화학적인 분류를 수행하여 Bacillus속으로 동정하였으며, Bacillus sp. KHI-15로 명명하였다 그리고 분리한 균주의 효소생산을 위한 배지조건과 배양조건을 측정하였다. 선발균주는 2% glucose, 0.5% yeast extract, 0.1% calcium chloride의 최적 배지에서 최대의 효소생산을보였다. 초기 pH7∼8과 4$0^{\circ}C$에서는 혈전용해능이 최대를 보였으며, 초기 pH6∼8과 30∼4$0^{\circ}C$에서는 $\beta$-glucosidase 효소활성의 생산이 가장 높았다.

• Journal of Microbiology and Biotechnology
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• 제9권4호
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• pp.504-508
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• 1999

This report compares the selective cytotoxic effects of Doenjang fermented by various Bacillus strains (Bacillus sp. SS9, SSA3, and PM3) on human liver cell lines with that of conventional Doenjang (DTY, DTG, and DTK) and commercial Doenjang (DCM, DCD, and DCS). To investigate selective cytotoxic effects of Doenjang extracts, the cell density of HepG2 (Hepatocellular carcinoma) and CCL-13 (cells derived from human normal liver) was estimated after addition of the extracts by using a viable cell counting method. The maximum selectivity ratio ($IC_{50}$value against CCL-13/$IC_{50}$ value aganist HepG2) was observed by PM3 (extracts of Doenjang fermented with Bacillus sp. PM3). As for morphological changes shown by the addition of PM3 into HepG2 and CCL-13 cultures, HepG2 was significantly disrupted, however, CCL-13 was not affected. Also, the growth rate of HepG2 was decreased significantly by the addition of PM3. Consequently, PM3 showed a more detrimental effect on HepG2 than that on CCL-13.

• Journal of Microbiology and Biotechnology
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• 제14권3호
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• pp.599-606
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• 2004

Gram-positive antagonistic bacilli were isolated from agricultural soils for possible use in biocontrol of plant pathogenic fungi, Fusarium oxysporum, Rhizoctonia solani, and/or Pythium ultimum. Among the 65 antagonistic Gram-positive soil isolates, 22 strains were identified as Bacillus species by 16S rDNA sequence analyses. Four strains, including DF14, especially exhibited multiple antagonistic properties against the three damping-off fungi. Genotypic properties of the Bacillus isolates were characterized by rapid molecular fingerprinting methods using repetitive extragenic palindromic-PCR (REP-PCR), ribosomal intergenic spacer-length polymorphisms (RIS-LP), 16S rDNA PCR-restriction fragment length polymorphisms (PCR-RFLP), and strain-specific PCR assays. The results indicated that the REP-PCR method was more valuable than the RIS-LP and 16S rDNA PCR-RFLP analyses as a rapid and reliable approach for bacilli typing and identification. The use of strain-specific primers designed based on 16S rDNA sequence comparisons enabled it to be possible to selectively detect a strain, DF14, which is being used as a biocontrol agent against damping-off fungi.

• 한국미생물·생명공학회지
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• 제19권6호
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• pp.614-618
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• 1991

토양세균 B.subtilis subsp. krictiensis로부터 항진균활성물질 KRF-001 복합체를 생산하기 위한 발효 조건을 조사하였다. Whey와 mannitol 등이 탄소원으로, CSL, corn gluten meal 그리고 polypeptone이 복합질소원으로 좋았다. 중온균인 생산균은 중성 pH조건에서 P.oryzae에 대한 bioactivity가 가장 높았으며, 0-10 DO의 낮은 용존산소 조건에서도 bioactivity가 유지되었다. 인산염의 농도가$ K_2HPO_4$, 0.047에서 0.097로 높아짐에 따라 1/2의 bioactivity 감소가 관찰되었다. 한편 UV 및 MNNG에 의한 돌연변이에 의해 우수균주 3개를 선별하였다.

• Journal of Microbiology and Biotechnology
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• 제13권5호
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• pp.692-699
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• 2003

The changes of physicochemical and microbiological states of Myeolchi-jeot, a Korean salted and fermented anchovy, were investigated during 20 days of storage at $4^{\circ}C,\;15^{\circ}C,\;and\;30^{\circ}C$. A total of 314 bacterial strains isolated from Myeolchi-jeot samples at different time intervals were identified, and their abilities to produce biogenic amines were determined by both decarboxylating agar media and HPLC analysis. The salinity and water activity of Myeolchi-jeot changed little, while the pH increased slightly over 20 days at the tested temperatures. A significant increase of total plate count was observed in the sample stored at $30^{\circ}C$. Staphylococcus spp. were dominant in Myeolchi-jeot, and its amine productivity was very weak. Bacillus spp. appeared increasingly with the progress of storage at all temperatures tested, and the increase was considerably dependent on the increase of storage temperature. Also, 58-73%, 83-90%, 81-90%, and 83-93% of Bacillus strains had the ability to produce histamine, tyramine, putrescine, and cadaverine, respectively. Therefore, the main amine producer in Myeolchi-jeot stored for a long period seems to be the genus Bacillus, especially B. licheniformis.

• 한국응용곤충학회지
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• 제34권3호
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• pp.243-248
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• 1995

효과적인 미생물 제제로 사용할 수 있는 Bacillus thuringiensis 균주들을 분리하기 위하여 경기도 일원의 72군데의 저곡창고에서 먼지를 채취하여 B. thuringiensis의 분포와 독성을 조사하였다. 총 411개의 채취된 저곡창고의 먼지에서 포자와 내독소 단백질을 생산하는 146개에 이르는 많은 수의 B. thuringiensis가 분리되었다. 저곡창고에서 분리된 146개 Bt의 독성 분포는 나비목의 누에 (Bombyx mori)유충에 독성을 띠는 균주가 84%로 가장 많이 분리되었고, 파리목의 빨간 집모기(Culex pipiens)유충에는 3%, 나비목과 파리목에 동시에 독성을 띠는 균주는 1%였다. 그러나 딱정벌레목의 쌀바구미(Sitophitus oryzae)에 독성을 띠는 균주는 분리되지 않았으며, 내독소 단백질은 형성하지만 독성을 띠지 않는 B. thuringiensis가 12%의 비율로 분리되어 흔히 존재함을 알 수 있었다. 이상의 결과로서 저곡창고는 B. thuringiensis의 유리한 분리장소임을 알 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제28권6호
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• pp.1030-1036
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• 2018

Bacillus strains produce various types of antibiotics, and random mutagenesis has traditionally been used to overproduce these natural metabolites. However, this method leads to the accumulation of unwanted mutations in the genome. Here, we rationally designed a single nucleotide substitution in the degU gene to generate a B. subtilis strain displaying increased plipastatin production in a foreign DNA-free manner. The mutant strain (BS1028u) showed improved antifungal activity against Pythium ultimum. Notably, pps operon deletion in BS1028u resulted in complete loss of antifungal activity, suggesting that the antifungal activity strongly depends on the expression of the pps operon. Quantitative real-time PCR and lacZ assays showed that the point mutation resulted in 2-fold increased pps operon expression, which caused the increase in antifungal activity. Likewise, commercial Bacillus strains can be improved to display higher antifungal activity by rationally designed simple modifications of their genome, rendering them more efficient biocontrol agents.