• International Journal of Oral Biology
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• v.38 no.2
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• pp.81-85
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• 2013

There are estimated to be about 700 species of bacteria in the oral cavity. Based on epidemiological investigations, some of these strains have been proposed as the pathogens responsible for oral diseases such as dental caries, gingivitis and periodontitis. Since electrolyzed hydrogen-rich water has been shown to have beneficial effects on human immunity, its use has increased. In our study, the antibacterial activity of hydrogen-rich water for oralagainst bacteria associated with oral disease was evaluated. The bacterial strains Streptococcus mutans, Fusobacterium nucleatum, Porphyromonas gingivalis and Tannerella forsythia were cultured in specific growth medium. S. mutans, F. nucleatum and P. gingivalis were soaked to thein both hydrogen water and tap water for 30 sec and then inoculated onto mitis-salivarius agar and brain heart infusion agar including supplemented withvitamin K and hemin, respectively. The numbers of bacterial colonies were then measured after cultivation for 48 hours. In the case of T. forsythia, which does not grow well on agar plates, inoculations into modified new oral spirochete (NOS) broth were performed and growth curve analysis was undertaken every day with a spectrophotometer. Hydrogen water showed antibacterial activity against all four bacterial strains in comparison with tap-water. We conclude from this that hydrogen water may have a positive impact on oral hygiene by helping to remove cariogenic bacteria and periodontopathogens.

• Microbiology and Biotechnology Letters
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• v.40 no.1
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• pp.76-81
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• 2012

Removal of methane, benzene and toluene was evaluated in a lab-scale biocover packed with a soil mixture of forest soil and earthworm cast (75:25 weight ratio). The bacterial community in the biocover was characterized using quantitative real-time PCR and terminal restriction fragment length polymorphism. Methane was removed at the upper layer of the biocover (-0.1 ~ -0.4 m), where the oxygen concentration was remarkably lower. The average removal efficiencies for methane and benzene/toluene were 90% and 99%, respectively. The pmoA gene copy numbers, responsible for methane oxidation, in the upper layer were higher than those in the lower layer. While type I methanotrohs dominated the lower layer, type II methanotrophs, such as Methylocystis and Methylosinus, were noted to be predominant in the upper layer. Benzene and toluene were removed from the lower layer (-0.6 ~ -0.9 m) as well as the upper layer. Moreover, the tmoA gene copy number, responsible for benzene/toluene oxidation, seen in the upper layer was not significantly different from those seen in the lower layer. These results suggest that a biocover packed with a soil and earthworm cast mixture is a promising method which could be utilized for the control of methane and volatile organic compounds such as benzene and toluene.

• Journal of the Korean Society of Groundwater Environment
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• v.2 no.1
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• pp.22-29
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• 1995

Mobile bacterial particles can act as carriers and enhance the transport of hydrophobic contaminants in ground water by reducing retardation effects. Because of their colloidal size and favorable surface conditions, bacteria can act as efficient contaminant carriers. When such carriers exist in a porous medium, the system can be thought of as three phases: an aqueous phase, a carrier phase, and a stationary solid matrix phase. Contaminant can be present in either or all of these phases. In this study, a mathematical model based on mass balances is developed to describe the transport and fate of biodegradable contaminant in a porous medium. Bacterial mass transfer mechanism between aqueous and solid matrix phases, and contaminant mass transfer between aqueous and bacterial phases are represented by kinetic models. Governing equations are non-dimensionalized and solved to analyze the bacteria facilitated contaminant transport. The numerical results of the facilitation effect match favorably with experimental data reported in the literature. Results show that the contaminant transport can be described by local equilibrium assumption when Damkohler numbers are larger than 10. Significant sensitivities to model parameters, particularly bacterial growth rate and influent bacterial concentration, were discovered.

• Journal of Forest and Environmental Science
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• v.34 no.1
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• pp.61-65
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• 2018

To know if small changes in rearing water temperature and density affect the number of bacterial and fungal colonies in metamorphosed frogs, Dybowski's frog tadpoles were reared from Gosner 25-26 stages at either low ($1^{\circ}C$ low to ambient water temperature), ambient, or high ($1^{\circ}C$ high) water temperature (each 15 tadpoles in 20 L water) condition and at either low (10 tadpoles/20 L water), medium (20 tadpoles), or high (30 tadpoles) density condition. Immediately after metamorphosis, we sampled bacteria and fungi from skin, liver, and heart of six metamorphosed frogs, randomly selected for each treatment group. After separate incubation of bacteria and fungi on 3M Petrifilm plates, we counted the number of bacterial and fungal colonies appeared on the plates and compared the numbers among the temperature and density treatment groups. For temperature treatment, high-temperature group had fewer bacterial colonies, while low-temperature group had more fungal colonies than the other two groups. For density treatment, low-density group had fewer bacterial colonies than the other two groups, but the number of fungal colonies were not different among the groups. Our results suggest that small increased rearing water temperature and lowered rearing density could potentially reduce pathogens in farming frogs.

• Korean Journal of Microbiology
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• v.38 no.4
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• pp.287-292
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• 2002

The composition of bacterial communities was detected in surface water of Cheonho Reservoir dominated by cyanobacteria, using fluorescent in situ hybridization (FISH) method. Total bacterial numbers were very high ranging from 0.6～$1.3{\times}10^7 \cells{\cdot}ml^-1$, whereas the ratio of Eubacteria to total bacteria was 29.8~45.8%, which was lower than that in other freshwater ecosystems. On average only 2.1% of DAPI-stained bacteria were detected by FISH with probes for $\alpha$, $\beta$, and $\gamma$-groups, respectively. Unknown eubacteria which was not bound to any probes except EUB 338, was relatively high. On the other hand, the Cytophaga-Flavobacterium group increased following the change of dominant species from Anabaena sp. to Microcystis sp. This result showed that bacterial communities could be affected by phytoplanktons, especially cyanobacteria.

• Biomedical Science Letters
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• v.28 no.4
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• pp.317-321
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• 2022

Due to COVID-19 pandemic, wearing face masks is obligatory to prevent respiratory virus transmissions in the community. However, there are few studies of the desirable number of wearing a face mask, and how to store them for reuse. Therefore, in this study, a survey was conducted among 208 healthy adults, and 27 kf-94 masks worn for 1, 2, and 3 days were collected. To estimate the risk of bacterial contamination, we analyzed the extent of bacterial contamination of the BHI medium and 16S rRNA gene sequencing. With an increase in the number of days of using the mask, the degree of bacterial contamination of the used mask gradually increased. As a result of 16S rRNA PCR performed for strain identification, Staphylococcus, known as a pathogenic bacterium, was identified the most. In conclusion, we found that wearing a cotton KF mask provides an optimal environment for microbes, which are related to the skin and respiratory system, to thrive. Therefore, it is also important to reduce the risk of bacterial infection of the face mask with appropriate sterilization methods.

• Toxicological Research
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• v.11 no.2
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• pp.289-294
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• 1995

This study was designed to observe the effect of tohiene pretreatment on leukocyte variation in whole blood and the oxygen free radical generating, scavenging enzyme activities in neutrophil of bacteria infected rats. Toluene was administered 7 times intraperitoneally at levels of 9.45 mM/kg body weight to the rats and then infected with S. aureus $2\times10^7$ cfu/ml. The toluene treated-rats showed the significantly decreased numbers of lymphocyte and monocytes, but the similiar numbers of neutrophils with the control. Furthermore the increased neutrophils in blood of bacteria infected rats were reduced by the toluene pretreatment. Concomitantly the increased activities of xanthine oxidase and superoxide dismutase in neutrophil of bacteria infected rats were also decreased by the toluene pretreatment. On the other hand, injection of benzaldehyde to rats also led to similiar results in the count of leukocytes, xanthine oxidase and superoxide dismutase activities of neutrophil with those of toluene treated rats. These data suggest that toluene and its intermediate metabolite, benzaldehyde influence on the phagocytosis and defence mechanism of neutrophil.

• Journal of Microbiology and Biotechnology
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• v.17 no.9
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• pp.1558-1562
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• 2007

To elucidate the influence of pipe materials on the VBNC (viable but nonculturable) state and bacterial numbers in drinking water, biofilm and effluent from stainless steel, galvanized iron, and polyvinyl chloride pipe wafers were analyzed. Although no HPC (heterotrophic plate count) was detected in the chlorinated influent of the model system, a DVC (direct viable count) still existed in the range between 3- and 4-log cells/ml. Significantly high numbers of HPC and DVC were found both in biofilm and in the effluent of the model system. The pipe material, exposure time, and the season were all relevant to the concentrations of VBNC and HPC bacteria detected. These findings indicate the importance of determining the number of VBNC cells and the type of pipe materials to estimate the HPC concentration in water distribution systems and thus the need of determining a DVC in evaluating disinfection efficiency.

• Proceedings of the Zoological Society Korea Conference
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• 1998.10b
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• pp.182.2-182
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• 1998

No Abstract, See Full Text

• Journal of the East Asian Society of Dietary Life
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• v.22 no.5
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• pp.593-603
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• 2012

This study was carried out to investigate the effects of pine needle extract on the color, hardness, springiness, chewiness, pH, thiobarbituric acid reactive substances (TBARS) value, and total bacterial number of seasoned pork meat stored at $4^{\circ}C$ for 9 days. The pH levels of sauce samples were not affected by the mixing rate of the extracts. Acidity, soluble solids, and salinity gradually increased as the amount of added extract increased. Total polyphenolic contents in the sauce ranged from $1.01{\pm}0.02$ mg GAE/mL to $1.41{\pm}0.04$ mg GAE/mL, DPPH radical scavenging activity ranged from $0.06{\pm}0.01$ AEAC to $0.12{\pm}0.01$ AEAC, and ABTS radical scavenging activity ranged from $0.11{\pm}0.01$ AEAC to $0.19{\pm}0.01$ AEAC. The pH levels significantly decreased as the amount of added extract increased. The lightness ($L^*$), redness ($a^*$) and yellowness ($b^*$) values of meat tended to decrease with longer storage period (p<0.05). Hardness and chewiness also increased with longer storage period (p<0.05). The TBARS values decreased as the amount of added extract increased after 6 days (p<0.05). Total bacterial numbers of P5, P10, and P15 decreased compared to the control (p<0.05). In the sensory evaluation, taste and palatability were not significantly different among C, P5, and P10 (p<0.05). Further, flavor, color, tenderness, and juiciness were not different among the seasoned pork meats. These results suggest that pine needle extract can inhibit protein degradation, lipid oxidation, and bacterial growth when used as an additive to seasoned pork meat.