• Proceedings of the Korean Society of Life Science Conference
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• 2003.05a
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• pp.68-68
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• 2003

• Microbiology and Biotechnology Letters
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• v.48 no.1
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• pp.12-23
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• 2020

Edible films containing antimicrobial agents can be used as safe alternatives to preserve food products. Essential oils are well-recognized antimicrobials. However, their low water solubility, volatility and high sensitivity to oxygen and light limit their application in food preservation. These limitations could be overcome by embedding these essential oils in complexed product matrices exploiting the encapsulation efficiency of β-cyclodextrin. This study focused on the maximization of β-cyclodextrin production using cyclodextrin glucanotransferase (CGTase) and the evaluation of its encapsulation efficacy to fabricate edible antimicrobial films. Response surface methodology (RSM) was used to optimize CGTase production by Brevibacillus brevis AMI-2 isolated from mangrove sediments. This enzyme was partially purified using a starch adsorption method and entrapped in calcium alginate. Cyclodextrin produced by the immobilized enzyme was then confirmed using high performance thin layer chromatography, and its encapsulation efficiency was investigated. The clove oil/β-cyclodextrin inclusion complexes were prepared using the coprecipitation method, and incorporated into chitosan films, and subjected to antimicrobial testing. Results revealed that β-cyclodextrin was produced as a major product of the enzymatic reaction. In addition, the incorporation of clove oil/β-cyclodextrin inclusion complexes significantly increased the antimicrobial activity of chitosan films against Staphylococcus aureus, Staphylococcus epidermidis, Salmonella Typhimurium, Escherichia coli, and Candida albicans. In conclusion, B. brevis AMI-2 is a promising source for CGTase to synthesize β-cyclodextrin with considerable encapsulation efficiency. Further, the obtained results suggest that chitosan films containing clove oils encapsulated in β-cyclodextrin could serve as edible antimicrobial food-packaging materials to combat microbial contamination.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.208-214
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• 2009

To avoid ambiguity in counting the number of colony, about 1,500 of colonies grown on B. cereus selective agar plates were grouped into 12 types by morphological difference and then identified by biochemical and 16S rDNA nucleotide sequence. Among them, seven colony types with 11 to 15 mm diameters of halo were identified as B. cereus or B. cereus subsp. cytotoxis. Five mm sized colonies with no halo, which have not been considered as B. cereus according to the manufacturer's manual, were identified as B. cereus. A colony type with double halos of only 6 mm in diameter was also B. cereus. Other three types were proven to be Enterococcus sp., Brevibacillus sp., and B. subtilis, respectively. PCR results showed that only 9 types that are identified as B. cereus strains harbor at least one of B. cereus toxin genes.

• Microbiology and Biotechnology Letters
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• v.42 no.2
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• pp.99-105
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• 2014

A Bacillus strain capable of hydrolyzing locust bean gum was isolated as a producer of extracellular mannanase by way of an enrichment culture in an acidic medium from homemade soybean pastes. The isolate YB-1401 showed a biochemical identity of 61.1% with Brevibacillus laterosporus, while the nucleotide sequence of its 16S rDNA had the highest similarity with that of Bacillus amyloliquefaciens. The mannanase productivity of the Bacillus sp. YB-1401 was drastically increased by mannans. Particularly, maximum mannanase productivity was reached at approximately 265 U/ml in LB medium supplemented with konjac glucomannan (4.0%). The mannanase was the most active at $55^{\circ}C$ and pH 5.5. Mannanase activity was completely maintained after pre-incubation at pH 3.5 to 11.0 for 1 h. The predominant products resulting from the mannanase hydrolysis were mannobiose and mannotriose for LBG, guar gum or mannooligosaccharides. A small amount of mannose was also detected in the hydrolyzates.

• Korean Journal of Microbiology
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• v.45 no.1
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• pp.74-81
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• 2009

In this research, we investigated the actual conditions of water purification systems at ten elementary schools located in Gunsan, Korea from July to December, 2007. The results were as follows; The population densities of heterotrophic bacteria in water purifiers ranged from 0 to $1.2{\pm}0.2{\times}10^4$ CFU/ml and those of tap water were in the range from 0 to $1.9{\pm}0.3{\times}10^4$ CFU/ml during investigation periods. Ninety percentage of purified water samples in July and September, 87.2% in October and November, and 93.7% in December turned out not to be suitable for drinking. The seasonal variation of the population densities of heterotrophic bacteria from purified waters was not notable. The total coliform, Salmonella and Shigella were not detected in purified water and tap water during investigation periods. Forty-five species of bacteria were isolated from water purifiers. The identified bacterial genera were Sphingomonas, Methylobacterium, Caulobacter, Novosphingobium, Bosea, Brevundimonas, Aminobacter, Ralstonia, Mitsuaria, Variovorax, Acidovorax, Massilia, Pseudomonas, Acinetobacter, Aeromonas, Bacillus, Staphylococcus, Brevibacillus, Microbacterium, Lapillicoccus, Micrococcus, Arthrobacter, Janibacter, Flavobacterium, Chryseobacterium, and Hymenobacter: Among the isolates, opportunistic pathogens such as Pseudomonas fluorescens, Staphylococcus epidermidis, Flavobacterium johnsoniae, and Acinetobacter johnsonii were also found.

• Environmental Engineering Research
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• v.22 no.1
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• pp.61-74
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• 2017

This study investigated the effect of various cations ($Ca^{2+}$, $Mg^{2+}$, $Al^{3+}$, $Mn^{2+}$, $Zn^{2+}$) on the autoaggregation (AAg) and surface hydrophobicity (SHb) of three different bacteria (Brevibacillus panacihumi strain (ZB1), Lysinibacillus fusiformis strain (ZB2) and Enterococcus faecalis strain (ZL)) using a 2-level factorial design. The AAg ratio was measured from the changes in the absorbance of the media. Results show that ZB2 had maximum AAg for the three bacteria investigated. A microscopic clustering of cells was observed when $Ca^{2+}$ was added to ZB2. The AAg was in the range of 62%, 58% and 34% for ZB2, ZB1 and ZL, respectively and correlated to the SHb. The aggregation and SHb of the microbial cells increased with increasing ionic strength due to the repulsive steric or overlap forces between the polymer covered surfaces. $Ca^{2+}$ demonstrated a more significant effect on aggregation and SHb of microbial cells due to an attractive binding force.

• Environmental Engineering Research
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• v.25 no.1
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• pp.29-35
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• 2020

The aim of this study was to estimate the microbial metabolic activity of indigenous soil microbes under the radon exposure with different intensity and times in the secured laboratory radon chamber. For this purpose, the soil microbes were collected from radon-contaminated site located in the G county, Korea. Thereafter, their metabolic activity was determined after the radon exposure of varying radon concentrations of 185, 1,400 and 14,000 Bq/㎥. The average depth variable concentrations of soil radon in the radon-contaminated site were 707, 860 and 1,185 Bq/㎥ from 0, 15, and 30 cm in deep, respectively. Simultaneously, the soil microbial culture was mainly composed of Bacillus sp., Brevibacillus sp., Lysinibacillus sp., and Paenibacillus sp. From the radon exposure test, higher or lower radiation intensities compared to the threshold level attributed the metabolic activity of mixed microbial consortium to be reduced, whereas the moderate radiation intensity (i.e. threshold level) induced it to the pinnacle point. It was decided that radon radiation could instigate the microbial metabolic activity depending on the radon levels while they were exposed, which could consequently address that the certain extent of threshold concentration present in the ecosystem relevant to microbial diversity and population density to be more proliferated.

• Food Science of Animal Resources
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• v.31 no.3
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• pp.405-412
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• 2011

The purpose of this study was to isolate and characterize bacteriocin-producing bacteria against Clostridium perfringens from domestic animals to determine their usefulness as probiotics. The feces of cattle and chicken were used as sources to isolate bacteriocin-producing bacteria using the spot-on-lawn method. In total, 900 bacterial stains were isolated from domestic animal feces, and 19 strains were finally selected after determining the inhibitory activity against the pathogenic indicator C. perfringens KCTC 3269. Eighteen strains of Bacillus subtilis and one strain of Brevibacillus parabrevis were identified by 16s rRNA sequencing. Most of the bacterial strains isolated were resistant to 0.5% bile salts and remained viable after 2 h at pH 3.0. Additionally, some B. subtilis strains showed strong inhibitory activity against Listeria monocytogenes. We isolated and screened B. subtilis strains CB 153 and CB 189 from cattle and B. subtilis MSC 156 and B. parabrevis MSC 164 from chickens using probiotic selection criteria such as inhibition activity against C. perfringens and tolerance to acid and bile salts. The isolated bacteriocin-producing bacteria and/or bacteriocin have the potential to be used as probiotics in the livestock industry.

• Journal of Species Research
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• v.5 no.2
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• pp.235-240
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• 2016

To investigate the indigenous prokaryotic species diversity in Korea, various environmental samples from diverse ecosystems were examined taxonomically. The isolated bacterial strains were identified based on 16S rRNA gene sequences, and those exhibiting at least 98.7% sequence similarity with known bacterial species but never reported in Korea were selected as unrecorded species. As an outcome of this study, 10 unrecorded bacterial species belonging to the phylum Firmicutes were discovered from various sources such as soil, tidal flat, fresh water, sea water, kimchi and gut of Fulvia mutica. The unrecorded species were assigned to 7 different genera of 5 families, namely Bacillus and Ornithinibacillus of Bacillaceae, Exiguobacterium of Exiguobacteriaceae, Brevibacillus and Paenibacillus of Paenibacillaceae, Staphylococcus of Staphylococcaceae, and Lactococcus of Streptococcaceae. The selected isolates were subjected to further taxonomic characterization including the analysis of Gram reaction, cellular and colonial morphology, biochemical activities, and phylogenetic trees. The descriptive information on the 10 unrecorded species are provided.

• Journal of Species Research
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• v.12 no.2
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• pp.158-164
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• 2023

In March 2021, marine sediment from East Sea samples were suspended in a 2% NaCl solution, and serial dilution was performed in fresh marine and Reasoner's 2A agar. Isolated bacterial strains were identified based on 16S rRNA gene sequences, and showed at least 98.7% sequence similarity with previously reported bacterial species. Finally, seven bacterial strains which were validly published but not reported in Korea, were obtained. These isolates were allocated to the orders Bacillales and Flavobacteriales. The three Flavobacteriales strains are classified into the family Flavobacteriaceae. The other four Bacillales belong to the families Bacillaceae and Paenibacillaceae. The seven unrecorded bacterial strains in this study are classified into seven different genera, which are assigned to Mesobacillus, Paenibacillus, Gramella, Gillisia, Arenibacter, Fictibacillus, and Brevibacillus. During the investigation, the possibility of excavation of various unrecorded species in domestic marine sediment was confirmed. Gram-staining, cell morphology, physiological and basic biochemical characteristics, and phylogenetic analysis were performed in this study and provided in the description of each strain.