• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.1
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• pp.48-56
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• 2024

Objectives: The coronavirus pandemic that began in 2019(COVID-19) has been one of the worst pandemics of the 21st century. Masks have been used to prevent COVID-19, but there are currently no standards for the long-term use of masks in the Republic of Korea. This study was conducted to assess the microbiological safety of KF94(Korea Filter 94) disposable face masks according to wearing duration by evaluating the bacterial filtration efficiencies of masks worn by research participants. Methods: A commercially available KF94 mask certified by the Ministry of Food and Drug Safety(MFDS) in the Republic of Korea was selected as the test mask. The research participants(n = 15) wore masks for the durations of one, three, and seven days. Participants also reported several parameters, including wearing time, makeup frequency, and storage. Bacterial filtration efficiencies of the worn masks were measured by a mask bioaerosol filtration tester. Staphylococcus aureus(S. aureus) was used as the test bacteria and quantitatively measured through the cultivation method. Then, bacterial filtration efficiency was calculated using the formula suggested by the MFDS. Results: All worn masks showed over 99.98% of mean bacterial filtration efficiency for S. aureus. There were no significant differences among bacterial filtration efficiencies of face masks according to wearing duration. There was also no significant difference among bacterial filtration efficiencies among participants. There was no correlation between the results of bacterial filtration efficiencies and reported parameters from participants. Conclusions: In the absence of significant external damage to the mask, the bacterial filtration efficiency of the mask can be maintained even after seven days of wearing. This result suggests that KF94 masks certified by the MFDS can be used repeatedly for about a week without loss of bacterial filtration efficiency.

• Journal of fish pathology
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• v.24 no.3
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• pp.279-287
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• 2011

Transcriptional response patterns of mud loach (Misgurnus mizolepis; Cypriniformes) hepcidin, a potential ortholog to human hamp1, in response to experimental challenges with non-pathogenic and pathogenic bacterial species were analyzed based on the semi-quantitative reverse transcription-PCR assay. Mud loach hepcidin transcripts were much more preferentially induced by pathogenic bacterial species (Edwardsiella tarda and Vibrio anguillarum) causing apparent pathological symptoms than by non-pathogenic species (Escherichia coli and Bacillus thuringiensis) displaying neither clinical signs nor mortality. However in overall, the induced amounts of hepcidin transcripts were positively related with the number of bacterial cells delivered in both pathogenic and non-pathogenic bacterial species. Inducibility of hepcidin transcripts were variable among three tissues examined (liver, kidney and spleen) in which kidney and spleen were more responsive to the bacterial challenge than liver. Time course expression patterns of hepcidin mRNAs after challenge were different between groups challenged with pathogenic and non-pathogenic species, although the overall pattern of hepcidin expression was in accordance with that generally observed in battery genes appeared during early phase of inflammation. Fish challenged with E. coli (non-pathogenic) showed the significant induction of hepcidin transcripts within 24 hr post injection (hpi) but the level was rapidly declined to the basal level either at 48 or 96 hpi. On the other hand, hepcidin transcript levels in E. tarda (pathogenic)-challenged fish were continuously elevated until 48 hpi, then downregulated at 96 hpi, although the level at 96 hpi was still significantly higher than control level observed in non-challenged fish. This expression pattern was consistent in all the three tissues examined. Taken together, our data indicate that hepcidin is tightly in relation with pathological and/or inflammation status during bacterial challenge, consequently providing useful basis to extend knowledge on the host defensive roles of hepcidin under infectious conditions in bony fish.

• Journal of Pharmacopuncture
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• v.10 no.3
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• pp.47-52
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• 2007

Objective This experimental study was performed to investigate the effect of Coptidis rhizoma extract compared with quantity on Staphylococcus aureus that induce keratitis. Methods Minimal inhibitory concentration(MIC) was measured by dropping to $50{\mu}l$　according to density Coptidis rhizoma extract(100%, 10%, 1%, 0.1%) compared with quantity(40g, 80g, 160g). Anti-bacterial potency was measured by the size of inhibition zone with change of volume. Results 1. MIC on Staphylococcus aureus in Coptidis rhizoma extract was showed anti-bacterial potency compared with quantity and density in 100% and 10% of all samples(40g, 80g, 160g). 2. MIC on Staphylococcus aureus in Coptidis rhizoma extract(40g, 80g, 160g) was showed anti-bacterial potency compared with quantity all samples($20{\mu}l,\;30{\mu}l,\;40{\mu}l,\;50{\mu}l$) in 100% density. 3. MIC on Staphylococcus aureus in Coptidis rhizoma extract(40g, 80g, 160g) was showed anti-bacterial potency compared with quantity all samples ($20{\mu}l,\;30{\mu}l,\;40{\mu}l,\;50{\mu}l$) in 100% density. Anti-bacterial potency of 80g Coptidis rhizoma extract decreased compared with 40g. Anti-bacterial potency of 160g Coptidis rhizoma extract decreased compared with 40g in $20{\mu}l,\;30{\mu}l$. Conclusions Coptidis rhizoma extract was showed anti-bacterial potency compare with quantity and density. In herbal drug, antibacterial potency compare with quantity and density must be studied.

• Journal of Sericultural and Entomological Science
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• v.37 no.1
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• pp.86-91
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• 1995

Isolation and pathogenicity of Fusarium spp. from mulberry shoot rot and severity of diseases which were known as bacterial blight were examined on four mulberry varieties in Suwon, Kongju and Chuncheon, A symptom of mulberry shoot rot was initiated long brown spot on young leaves and shoots. It was developed into dark brown spot and produced white mycelia and spores on the diseased symptoms. A symptom of bacterial blight showed leaf rolling and water soaking spot and produced bacterial ooze on leaf and shoot However later stage of upper two types of symptom was hardly distinguished. Severities of shoot rot and bacterial blight were 7.5% and 4.4% in Suwon, respectively. Isolation of Fusarium spp. on shoot rot symptoms was highter than that on bacterial blight symptoms, but isolation of Pseudomonas spp. was higher on bacterial blight symptoms. Trends of pathogenicity of Fusarium spp. and Pseudomonas spp. were similar to inoculation works, and isolations of pathogenic Fusarium spp. from center of symptom was higher than that from 30cm of symptom of all samples in three cultivation areas. Disease severities of shoot rot on variety of Kaeryangppong were 13.9%, 15.9% and 17.2% in Suwon, Kongju and Chuncheon, respectively. However variety of Cheongolppong was highly resistant to shoot rot disease in three cultivation areas.

• Korean Journal of Veterinary Service
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• v.31 no.4
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• pp.547-554
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• 2008

Bacteriospermia is a frequent finding in fresh boar semen and can result in detrimental effects on semen quality and longevity. The objectives of this study was to evaluate types of bacterial contaminants in porcine fresh semen and the reducing effect of antibiotic and density gradient with percoll on the bacterial contaminants. Fresh semen was collected by gloved-hand method into a pre-warmed($37^{\circ}C$) thermostable bottle, and was inoculated onto blood agar and MacConkey agar, respectively. After incubated for 48 hour, 7.5% $CO_2$ at $37^{\circ}C$, bacterial colonies were selected and identified by Gram staining, oxidase test, catalase test and finally identified using API kits and Vitek system. Aerobic culture yielded a variety of bacteria from different genera. The most prevalent contaminant of fresh semen were Leclecia adecarboxylata, Acineobacter banmanni, Staphylococcus epidermidis, Staphylococcus cohni spp urealyticus, Proteus mirabilis. Most of identified bacteria were Gram(-) and non-pathogenic bacteria. It seems that bacterial contaminants in fresh semen were seem originated from multiple sources at the stud/farm, and were from animal and non-animal origins. Gentamicin treatment did not eliminate the bacterial contaminants completely but 3 step-density gradient with percoll completely removed the bacterial contaminants in fresh semen. Therefore, future study is necessary to prove that density gradient method with percoll can eliminate bacteria in fresh semen without significantly affecting sperm viability or function.

• The Journal of the Korea Contents Association
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• v.17 no.12
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• pp.64-76
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• 2017

Biolgical activated carbon (BAC) processes are known to effectively remove organic pollutants in raw water, and biomass and attached bacterial species play an important role in removing process. In the present study, changes of bacterial biomass in granular activated carbon (GAC) process according to the depth and operating period were investigated. In addition, changes of bacterial biomass were also confirmed after UV exposure prior to the GAC process. Results from this this study showed that the bacterial biomass was decreased dependently according to the depth of GAC process. In case of UV pre-treatment, the bacterial biomass was declined significantly over the period of operation. However, changes in bacterial community were not shown during operation period without UV pre-treatment process. In conclusion, findings from this study may provide the useful information about the management of BAC process.

• Microbiology and Biotechnology Letters
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• v.36 no.2
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• pp.115-120
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• 2008

Bacterial populations from the rhizosphere were obtained and the efficacy of the bacterial wilt suppression, root colonizing ability and resistance to three kinds of chemical pesticides were assayed. According to these results, SKU48-2 was selected as a potential biological agent to control the bacterial wilt caused by Ralstonia solanacearum. SKU48-2 strain at $10^8CFU/ml$ inoculum was able to suppress the bacterial wilt up to 60% in greenhouse trials. Also, the resistance of SKU48-2 to chemical pesticides make possible to use in combination with chemical pesticides for the control of bacterial wilt. Three different powder formulations of SKU48-2 were developed. The shelf-life of powder formulations was effective up to 6 months of storage. Unformulated bacterial suspension could not be stored for 2 weeks, at which time cell viability was completely lost. According to 16S rDNA sequence data, the SKU48-2 stain was identified as Bacillus subtilis.

• Environmental Engineering Research
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• v.16 no.4
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• pp.219-225
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• 2011

The objective of this study was to investigate the bacterial adhesion to iron (hydr)oxide-coated sand (IHCS) and aluminum oxidecoated sand (AOCS) in the presence of Tween 20 (nonionic surfactant) and lipopeptide biosurfactant (anionic surfactant) through column experiments. Results show that in the presence of Tween 20, bacterial adhesion to the coated sands was slightly decreased compared to the condition of deionized water; the mass recovery (Mr) increased from 0.491 to 0.550 in IHCS and from 0.279 to 0.380 in AOCS. The bacterial adhesion to the coated sands was greatly reduced in lipopeptide biosurfactant; Mr increased to 0.980 in IHCS and to 0.797 in AOCS. Results indicate that the impact of lipopeptide biosurfactant on bacterial adhesion to metal oxide-coated sands was significantly greater than that of Tween 20. Our results differed from those of the previous report, showing that Tween 20 was the most effective while the biosurfactant was the least effective in the reduction of bacterial adhesion to porous media. This discrepancy could be ascribed to the different surface charges of porous media used in the experiments. This study indicates that lipopeptide biosurfactant can play an important role in enhancing the bacterial transport in geochemically heterogeneous porous media.

• The Journal of Natural Sciences
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• v.16 no.1
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• pp.143-154
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• 2005

To define the ecological roles of bacterial community in Daechung Reservoir. Vertical variation of total bacterial numbers were estimated at MAN site for one year with DAPI staining. The bacterial numbers were counted, environmental factors were monitored at the surface, -5m, -10m, -15m and -25 m of MAN sited and tried to explain the vertical bacterial numbers with environmental factors. The bacterial number was $1.6-1.7.0 x10^6$ cells/ml at the surface, $2.3-11.0x10^6$ cells/ml at 5 m depth, $1.2-1.4.0x10^6$ cells/ml at 10 m depth, $1.4-15.0x10^6$ cells/ml at 15 m depth and $1.4-1.3.0x10^6$ cells/ml at 25 m depth. The Mean bacterial number at the surface was more that those at any other depth. The explanation of the vertical total bacterial numbers with environmental factors were suggested.

• Korean Journal of Medicinal Crop Science
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• v.28 no.3
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• pp.183-194
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• 2020

Background: This study investigated the effect of soil properties and soil bacterial community on early growth characteristics of wild-simulated ginseng (Panax ginseng C. A. Meyer) in coniferous and mixed forest experimental fields. Methods and Results: The soil bacterial community was analyzed using a high throughput sequencing technique (Illumina MiSeq sequencing). The relationship between the soil bacterial community, soil properties, and growth characteristics of wild-simulated ginseng were analyzed using principal coordinate analysis (PCoA) and the Pearson's correlation analysis. Soil properties and soil bacterial community showed significant difference with forest physiognomy. Results of Pearson's correlation analysis and PCoA showed that the soil properties (soil pH, organic matter, total nitrogen, and cation exchange capacity) and soil bacterial community had significant correlation with tree species ratio and early growth characteristics of wild-simulated ginseng. Conclusions: This study clearly demonstrated the effect of soil properties and soil bacterial community on early growth characteristics of wild-simulated ginseng in coniferous and mixed forest. Moreover, these results will help in the selection of suitable cultivation sites for wild-simulated ginseng.