• Journal of Microbiology and Biotechnology
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• v.31 no.1
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• pp.104-114
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• 2021

Petroleum-contaminated soil is considered among the most important potential anthropogenic atmospheric methane sources. Additionally, various rhizoremediation factors can affect methane emissions by altering soil ecosystem carbon cycles. Nonetheless, greenhouse gas emissions from soil have not been given due importance as a potentially relevant parameter in rhizoremediation techniques. Therefore, in this study we sought to investigate the effects of different plant and soil amendments on both remediation efficiencies and methane emission characteristics in diesel-contaminated soil. An indoor pot experiment consisting of three plant treatments (control, maize, tall fescue) and two soil amendments (chemical nutrient, compost) was performed for 95 days. Total petroleum hydrocarbon (TPH) removal efficiency, dehydrogenase activity, and alkB (i.e., an alkane compound-degrading enzyme) gene abundance were the highest in the tall fescue and maize soil system amended with compost. Compost addition enhanced both the overall remediation efficiencies, as well as pmoA (i.e., a methane-oxidizing enzyme) gene abundance in soils. Moreover, the potential methane emission of diesel-contaminated soil was relatively low when maize was introduced to the soil system. After microbial community analysis, various TPH-degrading microorganisms (Nocardioides, Marinobacter, Immitisolibacter, Acinetobacter, Kocuria, Mycobacterium, Pseudomonas, Alcanivorax) and methane-oxidizing microorganisms (Methylocapsa, Methylosarcina) were observed in the rhizosphere soil. The effects of major rhizoremediation factors on soil remediation efficiency and greenhouse gas emissions discussed herein are expected to contribute to the development of sustainable biological remediation technologies in response to global climate change.

• The Korean Journal of Ecology
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• v.26 no.6
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• pp.307-312
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• 2003

To study the diversity of heterotrophic bacteria isolated from intestine of starfish, Asterias amurensis, we collected starfishes from the coastal area near Jangheung-Gun, Jeollanam-Do, Korea during July, 2000. Population density and bacterial diversity in the intestine of starfish were measured. The results were as follows; The population densities of heterotrophic bacteria in the intestine of starfish were 8.65${\pm}$0.65${\times}10^3\;dfu\;g^{-1}$. Gram positive bacteria occupied 59% among 29 isolates. The community structure of dominant heterotrophic bacteria in the intestine of starfish consisted of Bacillaceae in the low G+C gram positive bacteria subphylum, Microbacteriaceae in the high G+C gram positive bacteria subphylum, and Alteromonadaceae in ${\gamma}$-Proteobacteria subphylum. Among eight strains of Bacillus spp., three strains showed more than 97% identity, but five strains showed about 90% identity with type strain on the basis of partial 16S rDNA sequence.

• Biomedical Science Letters
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• v.25 no.4
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• pp.431-435
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• 2019

Chlorine dioxide is an effective chemical to inhibit the growth of bacteria and viruses or to disinfect infected areas. In this study, the effects of chlorine dioxide on several bacteria in hospitals were analyzed. Alloiococcus otitis, Kocuria rosea, Leuconostoc mesenteroides spp. and Staphylococcus lentus as gram-positive bacteria and Acinetobacter lwoffii, Aeromonas salmonicida, Brucella melitensis, Oligella ureolytica as gram-negative bacteria were done for the inhibitory analysis. The growth and morphology of the bacteria were analyzed by placing a plastic stick which was called "FarmeTok (medistick/Puristic)" provided by Purgofarm, co, Ltd. to release ClO₂ (13 ppmv/hr) next to the plate where the bacteria were incubated for 24 hours. Less than 10 bacterial colonies were evaluated as having 99% inhibitory effect. The initial bacterial culture concentration of 0.5 McFaland turbidity was good for analyzing the chlorine dioxide inhibitory effect. All bacteria could be easily counted post 24 hr co-incubation with ClO₂, but A. otitis and A. lwoffii without ClO₂ gas were not countable due to very dispersed colony types which were not affected for result analysis. As shown in this study, the FarmeTok plastic stick, which discharges chlorine dioxide at 13 ppmv / hour, was evaluated to be sufficient to suppress the above bacteria in the hospital. Bacteria existing in the clinic such as this hospital will be used as a data to inhibit the growth of bacteria by using ClO₂, and molecular biology analysis using the gene of bacteria will be possible in the future rather than inhibiting the growth of bacteria itself.

• Microbiology and Biotechnology Letters
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• v.50 no.3
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• pp.375-386
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• 2022

In the present study, four distinctly colored bacterial isolates that show intense pigmentation upon brief ultraviolet (UV) light exposure are chosen. The strains are identified as Micrococcus luteus (Milky yellow), Cryseobacterium pallidum (Yellow), Cryseobacterium spp. (Golden yellow), and Kocuria turfanensis (Pink) based on their morphological and 16S rDNA analysis. Moderate salinity (1.25%), 25-37℃ temperature, and pH of 7.2 are found to be the most favorable conditions of growth and pigment production for all the selected isolates. The pigments are extracted using methanol: chloroform (1:1) and the purity of the pigments are confirmed by high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC). Further, Fourier transform infrared (FTIR) and UV-Visible spectroscopy indicate their resemblance with carotenoids and flexirubin family. The antioxidant activities of the pigments are estimated, and, all the pigments have shown significant antioxidant efficacy in 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picryl-hydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) assays. The UV protective property of the pigments is determined by cling-film assay, wherein, at least 25% of UV sensitive Escherichia coli survive with bio-pigments even after 90 seconds of UV exposure compared to control. The pigments also hold a good sun protective factor (SPF) value (1.5-4.9) which is calculated with the Mansur equation. Based on these results, it can be predicted that these bacterial pigments can be further developed into a promising antioxidant and UV-protectant for several biomedical applications.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.2
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• pp.118-126
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• 2002

To evaluate the correlations of microbial populations with soil healthiness and crop production and establish the criteria for microbial population of soil types. We analyzed the microbial community structure of 13 soils which were different in physical and chemical properties and cultivation methods. According to the analysis of microbial population suing the dilution plate method, the large differences of the microbial population structures among soil types were shown: aerobic bacteria $2-27{\times}10^6$, fluorescent Pseudomonas $1-1,364{\times}10^5$, Gram negative bacteria $1-126{\times}10^4$, and mesophilic Bacillus $1-110{\times}10^5$. The density of Gram negative bacteria was highest on red pepper cultivating soils (sample no. 4 and 6) of Umsung and Gesan, Chungbuk, and the density of the fluorescent Pseudomonas was highest on greenhouse soil (sample no. 7) of Jinju, Kyungnam. The crop productivity of three soils was high as compared with those of other soils. It was supposed that the density of fluorescent Pseudomonas and mesophilic Bacillus were correlated with the incresed crop production. By MIDI analysis, 579 strains isolated from 13 soils composed of a variety of microbes including 102 isolates of Agrobacterium, 112 isolates of Bacillus, 32 isolates of Pseudomonas, 44 isolates of Kocuria, and 34 isolates of Pseudomonas. Among the 624 isolates of Gram negative bacteria, Pseudomonas including P. putida and p. fluorescens occupied the highest density (51%), and Stenotrophomonas maltophilia and Burkholderia cepacia also appeared at high density. From RAPD analysis, the fluorescent Pseudomonas strains isolated from 13 soil types showed a high level of strain diversities and were grouped into 2 - 14 patterns according to soil types. Many of unknown bacteria were recovered from the paddy soil, and needed to be further characterized on the molecular basis.

• Journal of radiological science and technology
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• v.43 no.5
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• pp.359-365
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• 2020

This study aimed to investigate the causes of bacterial growth to prevent infection caused by ultrasound gel and gel containers in contact with patients during ultrasonography. To investigate bacterial contamination during manufacturing or storage, we cultured ultrasound gels originally supplied from three manufacturers. To analyze bacterial growth according to the lapse of time and frequency of use of the ultrasound gel container, the gel and container were cultured at regular intervals every week for 4 weeks. In addition, to determine the source of infection, the examiner's hand was inspected with hand plate and the degree of bacterial contamination was measured before the test. As a result of the study, bacteria were not detected in the gel provided at the initial supply, and in the gel and gel container used repeatedly for 4 weeks, the same bacteria residing on the skin were identified in the examiner's hand, such as Staphylococcus epidermidis, Micrococcus luteus, Leuconostoc mesenteroid spp cremoris, Kocuria rhizophila, and etc. Separated strains were classified as those of the low- or non-pathogenicity; however, most of these strains may render fatal consequences to patients of lower level of immunity due to acquired tolerance to antibiotics. At week 1, when the number of tests was the highest, 44 colonies were identified, and at week 4, when the number of tests was the lowest, 4 colonies were identified. As r=0.994, it was found that the number of colonies increased as the number of tests increased. In conclusion, it was confirmed that the cause of the infection was not the ultrasound gel, but the examiner's hand. The ultrasound gel or gel container may be contaminated by skin flora of examiner's hands, which can cause opportunistic infection in patients with low immunity. The ultrasound gel or gel container may be contaminated by skin flora of examiner's hands, which can cause opportunistic infection in patients with low immunity. Therefore, it was confirmed that thorough hand disinfection was necessary to block healthcare-associated infections.

• Food Science and Preservation
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• v.16 no.4
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• pp.567-572
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• 2009

We evaluated the microbiological quality of a facility in which freshly cut onions were prepared. The total plate counts on walls, equipment, and raw materials were ND (not detected) to $10^1$ CFU/100 $cm^2$, $10^0{\sim}10^3$ CFU/100 $cm^2$, and $10^3{\sim}10^4$ CFU/g, respectively. No coliforms were detected on walls however, coliforms were detected at concentrations of ND to $10^3$ CFU/100 $cm^2$ and $10^3{\sim}10^4$ CFU/g on equipment and raw materials, respectively. The total plate counts for falling and floating bacteria in the processing plant were ND to $10^0$CFU/plate and $10^1{\sim}10^2$ $CFU/m^3$, respectively. Pathogenic microorganisms such as Escherichia coli, Salmonella spp, Staphylococcus aureus, and Listeria monocytogenes were not detected on walls, equipment, or raw materials. Overall, the results of the study indicate that hygiene control at the fresh-cut processing plant should be improved.